Power Quality In Power Systems And Electrical Machines Ewald Fuchs

Power Quality In Power Systems And Electrical Machines Ewald Fuchs
Power Quality In Power Systems And Electrical Machines Ewald Fuchs
Power Quality In Power Systems And Electrical Machines Ewald Fuchs

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5. Preface
The increased use of power electronic components
within the distribution system and the reliance on
renewable energy sources which have converters as
interface between the source and the power system
lead to power quality problems for the operation of
machines, transformers, capacitors and power
systems. The subject of power quality is very broad
by nature. It covers all aspects of power system engi-
neering from transmission and distribution level
analyses to end-user problems. Therefore, electric
power quality has become the concern of utilities,
end users, architects and civil engineers as well as
manufacturers. The book is intended for undergradu-
ate or graduate students in electrical and other engi-
neering disciplines as well as for professionals in
related fields. It is assumed that the reader has
already completed electrical circuit analysis courses
covering basic concepts such as Ohm's, Kirchhoff's,
Ampere's and Faraday's laws as well as Norton and
Thevenin equivalent circuits and Fourier analysis. In
addition, knowledge of diodes and transistors and an
introductory course on energy conversion (covering
energy sources, transformers, simple control circuits,
rudimentary power electronics, transformers, single-
and three-phase systems as well as various rotating
machine concepts such as brushless DC machines,
induction and synchronous machines) is desirable.
This book has evolved from the content of courses
given by the authors at the University of Colorado
at Boulder, the Iran University of Science and Tech-
nology at Tehran and the Curtin University of Tech-
nology at Perth, Australia. The book is suitable for
both electrical and non-electrical engineering stu-
dents and has been particularly written for students
or practicing engineers who want to teach them-
selves through the inclusion of about 150 application
examples with solutions. More than 700 references
are given in this book: mostly journal and conference
papers as well as national and international stan-
dards and guidelines. The International System (SI)
of units has been used throughout with some refer-
ence to the American/English system of units.
Power quality of power systems affects all con-
nected electrical and electronic equipment, and is a
measure of deviations in voltage, current, frequency,
temperature, force, and torque of particular supply
systems and their components. In recent years there
has been considerable increase in nonlinear loads, in
particular distributed loads such as computers, TV
monitors and lighting. These draw harmonic cur-
rents which have detrimental effects including com-
munication interference, loss of reliability, increased
operating costs, equipment overheating, machine,
transformer and capacitor failures, and inaccurate
power metering. This subject is pertinent to engi-
neers involved with power systems, electrical
machines, electronic equipment, computers and
manufacturing equipment. This book helps readers
to understand the causes and effects of power quality
problems such as nonsinusoidal wave shapes, voltage
outages, harmonic losses, origins of single-time
events such as voltage dips, voltage reductions, and
outages, along with techniques to mitigate these
problems. Analytical as well as measuring techniques
are applied to power quality problems as they occur
in existing systems based on central power stations
and distributed generation mainly relying on renew-
able energy sources.
It is important for each power engineering student
and professional who is active in the area of distribu-
tion systems and renewable energy that he/she knows
solutions to power quality problems of electrical
machines and power systems: this requires detailed
knowledge of modeling, simulation and measuring
techniques for transformers, machines, capacitors
and power systems, in particular fundamental and
harmonic power flow, relaying, reliability and redun-
dancy, load shedding and emergency operation,
islanding of power system and its voltage and fre-
quency control, passive and active filtering methods,
and energy storage combined with renewable energy
sources. An intimate knowledge of guidelines and
standards as well as industry regulations and prac-
tices is indispensable for solving power quality

6. vi Preface
problems in a cost-effective manner. These aspects
are addressed in this book which can be used either
as a teaching tool or as a reference book.
Key features:
9 Provides theoretical and practical insight into
power quality problems of machines and systems.
9 125 practical application (example) problems with
solutions.
9 Problems at the end of each chapter dealing with
practical applications.
9 Appendix with application examples, some are
implemented in SPICE, Mathematica, and
MATLAB.
ACKNOWLEDGMENTS
The authors wish to express their appreciation to
their families in particular to wives Wendy and
Roshanak, sons Franz, Amir and Ali, daughters
Heidi and Maryam for their help in shaping
and proofreading the manuscript. In particular,
the encouragement and support of Dipl.-Ing.
Dietrich J. Roesler, formerly with the US Depart-
ment of Energy, Washington DC, who was one of
the first professionals coining the concept of power
quality more than 25 years ago, is greatly appreci-
ated. Lastly, the work initiated by the late Professor
Edward A. Erdelyi is reflected in part of this book.
Ewald F. Fuchs, Professor
University of Colorado
Boulder, CO, USA
Mohammad A.S. Masoum, Associate Professor
Curtin University of Technology
Perth, WA, Australia
March 2008

7. 1
CHAPTER
Introduction to Power Quality
The subject of power quality is very broad by nature.
It covers all aspects of power system engineering,
from transmission and distribution level analyses to
end-user problems. Therefore, electric power quality
has become the concern of utilities, end users, archi-
tects, and civil engineers as well as manufacturers.
These professionals must work together in develop-
ing solutions to power quality problems:
9 Electric utility managers and designers must build
and operate systems that take into account the
interaction between customer facilities and power
system. Electric utilities must understand the sen-
sitivity of the end-use equipment to the quality of
voltage.
9 Customers must learn to respect the rights of their
neighbors and control the quality of their nonlin-
ear loads. Studies show that the best and the
most efficient solution to power quality problems
is to control them at their source. Customers can
perform this by careful selection and control of
their nonlinear loads and by taking appropriate
actions to control and mitigate single-time distur-
bances and harmonics before connecting their
loads to the power system.
9 Architects and civil engineers must design build-
ings to minimize the susceptibility and vulnerabil-
ity of electrical components to power quality
problems.
9 Manufacturers and equipment engineers must
design devices that are compatible with the power
system. This might mean a lower level of har-
monic generation or less sensitivity to voltage
distortions.
9 Engineers must be able to devise ride-through
capabilities of distributed generators (e.g., wind
and solar generating plants).
This chapter introduces the subject of electric
power quality. After a brief definition of power
quality and its causes, detailed classification of the
subject is presented. The formulations and measures
used for power quality are explained and the impacts
of poor power quality on power system and end-use
devices such as appliances are mentioned. A section
Power Quality in Power Systems and Electrical Machines
ISBN 978-0-12-369536-9
is presented addressing the most important IEEE [1]
and IEC [2] standards referring to power quality.
The remainder of this chapter introduces issues that
will be covered in the following chapters, including
modeling and mitigation techniques for power
quality phenomena in electric machines and power
systems. This chapter contains nine application
examples and ends with a summary.
1.1 DEFINITION OF POWER QUALITY
i
Electric power quality has become an important part
of power systems and electric machines. The subject
has attracted the attention of many universities and
industries, and a number of books have been pub-
lished in this exciting and relatively new field
[3-12].
Despite important papers, articles, and books pub-
lished in the area of electric power quality, its defini-
tion has not been universally agreed upon. However,
nearly everybody accepts that it is a very important
aspect of power systems and electric machinery with
direct impacts on efficiency, security, and reliability.
Various sources use the term "power quality" with
different meaning. It is used synonymously with
"supply reliability," "service quality," "voltage
quality," "current quality," "quality of supply," and
"quality of consumption."
Judging by the different definitions, power quality
is generally meant to express the quality of voltage
and/or the quality of current and can be defined as:
the measure, analysis, and improvement of the bus
voltage to maintain a sinusoidal waveform at rated
voltage and frequency. This definition includes all
momentary and steady-state phenomena.
1.2 CAUSES OF DISTURBANCES IN
POWER SYSTEMS
Although a significant literature on power quality is
now available, most engineers, facility managers,
and consumers remain unclear as to what constitutes
a power quality problem. Furthermore, due to the
power system impedance, any current (or voltage)
harmonic will result in the generation and propaga-
9 Elsevier Inc.
All rights reserved.

8. 2 CHAPTER 1
system impedance [
(~" gt~'aCnabf~Smeline;' ~
/I
point of common ~/ [
coupling (PCC) [ I
harmonic voltage distortion at PCC due to propagation of
harmonic currents through the system impedance
sinusoidal
[ customer with linear and nonlinear loads
source voltage
~nonlinear loads (e.g., switched-mode
[ power supplies, AC drives, fluorescent
i "-~ lamps) drawing nonsinusoidal currents
from a perfectly sinusoidal voltage source
" r loads
customers with linear loads
!
harmonic voltage
distortion imposed
on other customers
I
FIGURE 1.1 Propagation of harmonics (generated by a nonlinear load) in power systems.
tion of voltage (or current) harmonics and affects the
entire power system. Figure 1.1 illustrates the impact
of current harmonics generated by a nonlinear load
on a typical power system with linear loads.
What are the origins of the power quality problem?
Some references [9] divide the distortion sources
into three categories: small and predictable (e.g.,
residential consumers generating harmonics), large
and random (e.g., arc furnaces producing voltage
fluctuations and flicker), and large and predictable
(e.g., static converters of smelters and high-voltage
DC transmission causing characteristic and unchar-
acteristic harmonics as well as harmonic instability).
However, the likely answers to the question are
these: unpredictable events, the electric utility, the
customer, and the manufacturer.
Unpredictable Events. Both electric utilities and end
users agree that more than 60% of power quality
problems are generated by natural and unpredict-
able events [6]. Some of these include faults, light-
ning surge propagation, resonance, ferroresonance,
and geomagnetically induced currents (GICs) due to
solar flares [13]. These events are considered to be
utility related problems.
The Electric Utility. There are three main sources of
poor power quality related to utilities:
9 The point ofsupply generation. Although synchro-
nous machines generate nearly perfect sinusoidal
voltages (harmonic content less than 3%), there
are power quality problems originating at generat-
ing plants which are mainly due to maintenance
activity, planning, capacity and expansion con-
straints, scheduling, events leading to forced
outages, and load transferring from one substation
to another.
9 The transmission system. Relatively few power
quality problems originate in the transmission
system. Typical power quality problems originat-
ing in the transmission system are galloping (under
high-wind conditions resulting in supply interrup-
tions and/or random voltage variations), lightning
(resulting in a spike or transient overvoltage),
insulator flashover, voltage dips (due to faults),
interruptions (due to planned outages by utility),
transient overvoltages (generated by capacitor
and/or inductor switching, and lightning), trans-
former energizing (resulting in inrush currents
that are rich in harmonic components), improper
operation of voltage regulation devices (which
can lead to long-duration voltage variations), slow
voltage variations (due to a long-term variation of
the load caused by the continuous switching of
devices and load), flexible AC transmission
system (FACTS) devices [14] and high-voltage
DC (HVDC) systems [15], corona [16], power line
carrier signals [17], broadband power line (BPL)
communications [18], and electromagnetic fields
(EMFs) [19].
9 The distribution system. Typical power quality
problems originating in the distribution system are
voltage dips, spikes, and interruptions, transient

9. Introduction to Power Quality 3
overvoltages, transformer energizing, improper
operation of voltage regulation devices, slow
voltage variations, power line carrier signals, BPL,
and EMFs.
The Customer. Customer loads generate a consider-
able portion of power quality problems in today's
power systems. Some end-user related problems are
harmonics (generated by nonlinear loads such as
power electronic devices and equipment, renewable
energy sources, FACTS devices, adjustable-speed
drives, uninterruptible power supplies (UPS), fax
machines, laser printers, computers, and fluorescent
lights), poor power factor (due to highly inductive
loads such as induction motors and air-conditioning
units), flicker (generated by arc furnaces [20]), tran-
sients (mostly generated inside a facility due to
device switching, electrostatic discharge, and arcing),
improper grounding (causing most reported cus-
tomer problems), frequency variations (when sec-
ondary and backup power sources, such as diesel
engine and turbine generators, are used), misappli-
cation of technology, wiring regulations, and other
relevant standards.
Manufacturing Regulations. There are two main
sources of poor power quality related to manufactur-
ing regulations:
9 Standards. The lack of standards for testing, certi-
fication, sale, purchase, installation, and use of
electronic equipment and appliances is a major
cause of power quality problems.
9 Equipment sensitivity. The proliferation of "sensi-
tive" electronic equipment and appliances is one
of the main reasons for the increase of power
quality problems. The design characteristics of
these devices, including computer-based equip-
ment, have increased the incompatibility of a wide
variety of these devices with the electrical environ-
ment [21].
Power quality therefore must necessarily be tackled
from three fronts, namely:
9 The utility must design, maintain, and operate the
power system while minimizing power quality
problems;
9 The end user must employ proper wiring, system
grounding practices, and state-of-the-art electronic
devices; and
9 The manufacturer must design electronic devices
that keep electrical environmental disturbances to
a minimum and that are immune to anomalies of
the power supply line.
1.3 CLASSIFICATION OF POWER
QUALITY ISSUES
To solve power quality problems it is necessary to
understand and classify this relatively complicated
subject. This section is based on the power quality
classification and information from references [6]
and [9].
There are different classifications for power quality
issues, each using a specific property to categorize
the problem. Some of them classify the events as
"steady-state" and "non-steady-state" phenomena.
In some regulations (e.g., ANSI C84.1 [22]) the most
important factor is the duration of the event. Other
guidelines (e.g., IEEE-519) use the wave shape
(duration and magnitude) of each event to classify
power quality problems. Other standards (e.g., IEC)
use the frequency range of the event for the
classification.
For example, IEC 61000-2-5 uses the frequency
range and divides the problems into three main cat-
egories: low frequency (<9 kHz), high frequency
(>9 kHz), and electrostatic discharge phenomena. In
addition, each frequency range is divided into "radi-
ated" and "conducted" disturbances. Table 1.1 shows
TAB L E 1.1 Main Phenomena Causing Electromagnetic and
Power Quality Disturbances [6, 9]
Conducted low-frequency phenomena
Harmonics, interharmonics
Signaling voltage
Voltage fluctuations
Voltage dips
Voltage imbalance
Power frequency variations
Induced low-frequency voltages
DC components in AC networks
Radiated low-frequency phenomena
Magnetic fields
Electric fields
Conducted high-frequency phenomena
Induced continuous wave (CW) voltages or currents
Unidirectional transients
Oscillatory transients
Radiated high-frequency phenomena
Magnetic fields
Electric fields
Electromagnetic field
Steady-state waves
Transients
Electrostatic discharge phenomena (ESD)
Nuclear electromagnetic pulse (NEMP)

10. 4 CHAPTER 1
p,
(9
>
| 110%
NI-,
0
"o 90%
t--
0")
t~
E
very short
overvoltage
very short
undervoltage
short long
overvoltage overvoltage
normal operating voltage
short long
undervoltage undervoltage
very long
overvoltage
very long
undervoltage
1-3 cycles 1-3 min 1-3 hours
duration of event
FIGURE 1.2 Magnitude-duration plot for classification of power quality events [11].
the principal phenomena causing electromagnetic
disturbances according to IEC classifications [9]. All
these phenomena are considered to be power quality
issues; however, the two conducted categories are
more frequently addressed by the industry.
The magnitude and duration of events can be used
to classify power quality events, as shown in Fig. 1.2.
In the magnitude-duration plot, there are nine dif-
ferent parts [11]. Various standards give different
names to events in these parts. The voltage magni-
tude is split into three regions:
9 interruption: voltage magnitude is zero,
9 undervoltage: voltage magnitude is below its
nominal value, and
9 overvoltage: voltage magnitude is above its
nominal value.
The duration of these events is split into four regions:
very short, short, long, and very long. The borders in
this plot are somewhat arbitrary and the user can set
them according to the standard that is used.
IEEE standards use several additional terms (as
compared with IEC terminology) to classify power
quality events. Table 1.2 provides information about
categories and characteristics of electromagnetic
phenomena defined by IEEE-1159 [23]. These cate-
gories are briefly introduced in the remaining parts
of this section.
1.3.1 Transients
Power system transients are undesirable, fast- and
short-duration events that produce distortions. Their
characteristics and waveforms depend on the mecha-
nism of generation and the network parameters
(e.g., resistance, inductance, and capacitance) at the
point of interest. "Surge" is often considered synony-
mous with transient.
Transients can be classified with their many char-
acteristic components such as amplitude, duration,
rise time, frequency of ringing polarity, energy
delivery capability, amplitude spectral density, and
frequency of occurrence. Transients are usually clas-
sified into two categories: impulsive and oscillatory
(Table 1.2).
An impulsive transient is a sudden frequency
change in the steady-state condition of voltage,
current, or both that is unidirectional in polarity (Fig.
1.3). The most common cause of impulsive transients
is a lightning current surge. Impulsive transients can
excite the natural frequency of the system.
An oscillatory transient is a sudden frequency
change in the steady-state condition of voltage,
current, or both that includes both positive and nega-
tive polarity values. Oscillatory transients occur for
different reasons in power systems such as appliance
switching, capacitor bank switching (Fig. 1.4), fast-
acting overcurrent protective devices, and ferroreson-
ance (Fig. 1.5).
1.3.2 Short-Duration Voltage Variations
This category encompasses the IEC category of
"voltage dips" and "short interruptions." According
to the IEEE-1159 classification, there are three dif-
ferent types of short-duration events (Table 1.2):
instantaneous, momentary, and temporary. Each
category is divided into interruption, sag, and swell.
Principal cases of short-duration voltage variations
are fault conditions, large load energization, and
loose connections.

11. Introduction to Power Quality 5
TABLE 1.2 Categories and Characteristics of Electromagnetic Phenomena in Power Systems as Defined by IEEE-1159 [6, 9]
Categories Typical spectral content Typical duration Typical voltage magnitude
1. Transient 1.1. Impulsive
9 nanosecond
9 microsecond
9 millisecond
1.2. Oscillatory
9 low frequency
9 medium frequency
9 high frequency
2. Short-duration 2.1. Instantaneous
variation 9 interruption
9 sag
9 swell
2.2. Momentary
9 interruption
9 sag
9 swell
2.3. Temporary
9 interruption
9 sag
9 swell
3. Long-duration 3.1. Sustained interruption
variation 3.2. Undervoltage
3.3. Overvoltage
4. Voltage imbalance
5. Waveform distortion
6. Voltage fluctuation
7. Power frequency
variations
i
5.1. DC offset
5.2. Harmonics
5.3. Interharmonics
5.4. Notching
5.5. Noise
5 ns rise <50 ns
I ps rise 50 ns-1 ms
0.1 ms rise >1 ms
<5 kHz 0.3-50 ms 0-4 pu
5-500 kHz 20 ps 0-8 pu
0.5-5 MHz 5 ~ts 0-4 pu
0-100th
0-6 kHz
Broadband
<25 Hz
0.5-30 cycles <0.1 pu
0.5-30 cycles 0.1-0.9 pu
0.5-30 cycles 1.1-1.8 pu
0.5 cycle-3 s <0.1 pu
30 cycles-3 s 0.1-0.9 pu
30 cycles-3 s 1.1-1.4 pu
3 s-1 min <0.1 pu
3 s-1 min 0.1--0.9 pu
3 s-1 min 1.1-1.2 pu
>1 min 0.0 pu
>1 min 0.8--0.9 pu
>1 min 1.1-1.2 pu
steady state 0.5-2%
steady state 0-0.1%
steady state 0--20%
steady state 0-2%
steady state
steady state 0-1%
intermittent 0.1-7%
<10 s
12
10
8
A
6
L
L
O
4
2
0

", i i
5 1'0 15 2;)
time (gs)
FIGURE 1.3 Impulsive transient current caused by lightning strike, result of PSpice simulation.

12. 6 CHAPTER 1
1.5
1.0
~, 0.5
g o
"~-0.5
-1.0 ~
time (ms)
-1.5 ! ! !
0 20 40 60
FIGURE 1.4 Low-frequency oscillatory transient caused by capacitor bank energization.
100
~ vv I ?
- 50
- 100
time Is)
I I I I I
0.1 0.2 0.3 0.4 0.5
FIGURE 1.5 Low-frequency oscillatory transient caused by ferroresonance of a transformer at no load, result of
Mathematica simulation.
Interruption. Interruption occurs when the supply
voltage (or load current) decreases to less than 0.1 pu
for less than 1 minute, as shown by Fig. 1.6. Some
causes of interruption are equipment failures, control
malfunction, and blown fuse or breaker opening.
The difference between long (or sustained) inter-
ruption and interruption is that in the former the
supply is restored manually, but during the latter
the supply is restored automatically. Interruption is
usually measured by its duration. For example,
according to the European standard EN-50160 [24]:
9 A short interruption is up to 3 minutes; and
9 A long interruption is longer than 3 minutes.
However, based on the standard IEEE-1250 [25]:
9 An instantaneous interruption is between 0.5 and
30 cycles;
9 A momentary interruption is between 30 cycles
and 2 seconds;
9 A temporary interruption is between 2 seconds
and 2 minutes; and
9 A sustained interruption is longer than 2
minutes.
Sags (Dips). Sags are short-duration reductions in
the rms voltage between 0.1 and 0.9 pu, as shown by
Fig. 1.7. There is no clear definition for the duration
of sag, but it is usually between 0.5 cycles and 1
minute. Voltage sags are usually caused by
9 energization of heavy loads (e.g., arc furnace),
9 starting of large induction motors,
9 single line-to-ground faults, and
9 load transferring from one power source to
another.

13. Introduction to Power Quality 7
A
o<
100
c
0
....
..,.
I,.
| 50
o')
0
E 0
0
time (ms)
i i i I~
1 2 3
FIGURE 1.6 Momentary interruptions due to a fault.
A
~) 100
> 0
-100
time (s)
' ~ '
0 50 1 0 150 200
FIGURE 1.7 Voltage sag caused by a single line-to-ground (SLG) fault.
o~ 120
c 115
0
m
9 =-- 110
> 105
O)
-~ 100
0
>
95
time (s)
I I I
O. 1 0.2 0.3
FIGURE 1.8 Instantaneous voltage swell caused by a single line-to-ground fault.
Each of these cases may cause a sag with a spe-
cial (magnitude and duration) characteristic. For
example, if a device is sensitive to voltage sag of
25 %, it will be affected by induction motor starting
[11]. Sags are main reasons for malfunctions of elec-
trical low-voltage devices. Uninterruptible power
supply (UPS) or power conditioners are mostly used
to prevent voltage sags.
Swells. The increase of voltage magnitude between
1.1 and 1.8 pu is called swell, as shown by Fig. 1.8.
The most accepted duration of a swell is from 0.5
cycles to 1 minute [7]. Swells are not as common as
sags and their main causes are
9 switching off of a large load,
9 energizing a capacitor bank, or
9 voltage increase of the unfaulted phases during a
single line-to-ground fault [10].
In some textbooks the term "momentary overvolt-
age" is used as a synonym for the term swell. As in
the case of sags, UPS or power conditioners are
typical solutions to limit the effect of swell [10].
1.3.3 Long-Duration Voltage Variations
According to standards (e.g., IEEE-1159, ANSI-
C84.1), the deviation of the rms value of voltage
from the nominal value for longer than 1 minute is

14. 8 CHJ~PIEP, $
called long-duration voltage variation. The main
causes of long-duration voltage variations are load
variations and system switching operations. IEEE-
1159 divides these events into three categories
(Table 1.2): sustained interruption, undervoltage,
and overvoltage.
Sustained Interruption. Sustained (or long) inter-
ruption is the most severe and the oldest power
quality event at which voltage drops to zero and
does not return automatically. According to the IEC
definition, the duration of sustained interruption is
more than 3 minutes; but based on the IEEE defini-
tion the duration is more than 1 minute. The number
and duration of long interruptions are very impor-
tant characteristics in measuring the ability of a
power system to deliver service to customers. The
most important causes of sustained interruptions
are
9 fault occurrence in a part of power systems with
no redundancy or with the redundant part out of
operation,
9 an incorrect intervention of a protective relay
leading to a component outage, or
9 scheduled (or planned) interruption in a low-
voltage network with no redundancy.
Undervoltage. The undervoltage condition occurs
when the rms voltage decreases to 0.8-0.9 pu for
more than 1 minute.
Overvoltage. Overvoltage is defined as an increase in
the rms voltage to 1.1-1.2 pu for more than 1 minute.
There are three types of overvoltages:
9 overvoltages generated by an insulation fault, fer-
roresonance, faults with the alternator regulator,
tap changer transformer, or overcompensation;
9 lightning overvoltages; and
9 switching overvoltages produced by rapid modifi-
cations in the network structure such as opening
of protective devices or the switching on of capaci-
tive circuits.
1.3.4 Voltage Imbalance
When voltages of a three-phase system are not
identical in magnitude and/or the phase differences
between them are not exactly 120 degrees, voltage
imbalance occurs [10]. There are two ways to calcu-
late the degree of imbalance:
9 divide the maximum deviation from the average
of three-phase voltages by the average of three-
phase voltages, or
9 compute the ratio of the negative- (or zero-)
sequence component to the positive-sequence
component [7].
The main causes of voltage imbalance in power
systems are
9 unbalanced single-phase loading in a three-phase
system,
9 overhead transmission lines that are not
transposed,
9 blown fuses in one phase of a three-phase capaci-
tor bank, and
9 severe voltage imbalance (e.g., >5%), which can
result from single phasing conditions.
1.3.5 Waveform Distortion
A steady-state deviation from a sine wave of power
frequency is called waveform distortion [7]. There
are five primary types of waveform distortions: DC
offset, harmonics, interharmonics, notching, and
electric noise. A Fourier series is usually used to
analyze the nonsinusoidal waveform.
DC Offset. The presence of a DC current and/or
voltage component in an AC system is called DC
offset [7]. Main causes of DC offset in power systems
are
9 employment of rectifiers and other electronic
switching devices, and
9 geomagnetic disturbances [6, 7, 13] causing GICs.
The main detrimental effects of DC offset in alter-
nating networks are
9 half-cycle saturation of transformer core [26-28],
9 generation of even harmonics [26] in addition to
odd harmonics [29, 30],
9 additional heating in appliances leading to a de-
crease of the lifetime of transformers [31-36], rotat-
ing machines, and electromagnetic devices, and
9 electrolytic erosion of grounding electrodes and
other connectors.
Figure 1.9a shows strong half-cycle saturation in a
transformer due to DC magnetization and the influ-
ence of the tank, and Fig. 1.9b exhibits less half-cycle
saturation due to DC magnetization and the absence
of any tank. One concludes that to suppress DC cur-
rents due to rectifiers and geomagnetically induced
currents, three-limb transformers with a relatively
large air gap between core and tank should be used.
Harmonics. Harmonics are sinusoidal voltages or
currents with frequencies that are integer multiples
of the power system (fundamental) frequency
(usually, f - 50 or 60 Hz). For example, the frequency

15. Introduction to Power Quality 9
m
e-
.=
L
(.1
"0
m
m
01
m
I
m
d=l
e"
==
t_
0
"0
C
m
m
G}
O)
m
I
0
>
1000 -
._
- 1000 -
- 2000-
A
1000 --
,,
- 1000-
- 2000-
,v a Vc
......... _,~ / iX / l
7 XX t ~:~",,-/
r r ~
!1
l !ic
V
............ l
/'~d
\-/
iiiii i ll ~' 7
i
I
\:
v
Vb
/ f
iV,_ .,/
f\,,X
i! .......... '~i
i ......... 9 ............ _
!ia
90 180
angle (degrees)
(a)
270 360
............... )t ................... J.--..i
;Hi ........ J ................ A/
L ............. i
~~rib
90
i.. vc ,.~ ~ ............ 'Vb ~i
la ~- i~
11|0
angle (degrees)
(b)
! ......
I ,! ........ !
270
160
FIGURE 1.9 Measured voltages and currents at balanced DC bias current IDC =--2 A for a 2.3 kVA three-limb transformer
(a) at full load with tank (note the strong half-cycle saturation) and (b) at full load without tank (note the reduced half-
cycle saturation) [27]. Dividing the ordinate values by 2.36 and 203 the voltages in volts and the currents in amperes are
obtained, respectively.
of the hth harmonic is (hf). Periodic nonsinusoidal
waveforms can be subjected to Fourier series and
can be decomposed into the sum of fundamental
component and harmonics. Main sources of harmon-
ics in power systems are
9 industrial nonlinear loads (Fig. 1.10) such as power
electronic equipment, for example, drives (Fig.
1.10a), rectifiers (Fig. 1.10b,c), inverters, or loads
generating electric arcs, for example, arc furnaces,
welding machines, and lighting, and
9 residential loads with switch-mode power supplies
such as television sets, computers (Fig. 1.11), and
fluorescent and energy-saving lamps.
Some detrimental effects of harmonics are

16. 10 CHAPTER 1
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II~ 9 ~ I I I __! ~I I ~ I If I I I I It I_ l I I_ ~L I II I I I II I I l__IL _ I
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I ' ' i I i i I i''l~'l I I i i ~ I i I I I ' ' I ' i i i i i I ~ I i i ;
I~ time
0.4ms 0.8ms 1.2ms 1.6ms
(a)
time
2ms
. e-..-- .
400V J
M
jr-
%
/"
,B -f
O- J
jr-
/
- 400V. ~---
400V"
- 400V. rr--~" ~"--"~"" I
Jf
I
I
I
I
I
t "- time
L
I"- "1
" time
time
time
32ms 36ms 40ms 44ms
(b)
FIGURE 1.10 (a) Computed electronic switch (upper graph) and motor (lower graph) currents of an adjustable-speed
brushless DC motor drive for a phase angle of O = 0 ~ [29]. (b) Voltage notching caused by a three-phase rectifier for a firing
angle of a = 50 ~ result of PSpice simulation. Top: phase current; second from top: line-to-line voltage of rectifier; third from
top: line-to-line voltages of infinite bus; bottom: DC output voltage of rectifier.
9 maloperation of control devices,
9 additional losses in capacitors, transformers, and
rotating machines,
9 additional noise from motors and other
apparatus,
9 telephone interference, and
9 causing parallel and series resonance frequencies
(due to the power factor correction capacitor and
cable capacitance), resulting in voltage amplifica-
tion even at a remote location from the distorting
load.
Recommended solutions to reduce and control har-
monics are applications of high-pulse rectification,
passive, active, and hybrid filters, and custom power
devices such as active-power line conditioners
(APLCs) and unified power quality conditioners
(UPQCs).

17. Introduction to Power Quality 11
2kV
.... i .... i...i ......... i .... i...i ........ ~ .... i...i ......... i .... i...i ........ i .... i...i ......... ~._.~ .... i ....... ~ .... i...~ ......... i...i .... :=
.... i .... i .... :: ......... i .... :: .... i ........ i .... i .... :: ......... i .... :: .... i ....... i .... i-..i ......... i...i .... i ......... i .... i--.i ......... ~...i .... :~
.... i----" .... i ....... i .... i----,: ........ !--.." .... i
', ', ', ', ' l ', ',
lkV. :: :: :: .... ii,~,.~ .
;iVAB i i ~ ~ i ~ ~ :~ i i i ~ i ~ ~
--~~ !i--i .... ~,-! ~ ~, it~-
.... ! ~ ,~..., ,..:i::::[:::!::::i:::!:::: :..:.iii;i::i!:::_'.:::i::.r::i::::i:::[: '~ .... i.:::
.... .... .... .... .... i i .... ..... .... i .... i~ .............
O-
- lkV.
- 2kV.
....................... i .... i...i ....
, ~ ,
.... i i i-
,, ,, ,, ,, ,, :~. ', ,, ,,
.... i i...~ .... .... "~L~! r i i i :,.ii -r .... ; ~: ..... ~...iit ----i---~'---i----~ - .... i i---i .... ......... i---i i .... .... ~---i-~,,
.... ~ .... i .... i .... ~ .... i .... ::-.~-i ....... ~ .... i .... :: .... , .... i .... :: .... i ....... i.--: :---,---L-~ .... ~--.
.... i .... i .... il ......... i .... ii~! .... i .... ii ......... i .... ii .... i ....
~ ~,,,,,
"~ .... i:~ ......... ~i .... i ...... i .... i! ....
.... : .... :---: ......... : .... :---: ........ " .... i---: ..... ~..vy,:.....', t .... i---" ......... "---~ .... i-.-~ .... i .... i---~ .... ...~V~.:._i ....... i .... i..-"
l : ~ : : : : : : : : Vab : : 1 ' ' ' J~ .........
.... ~ .... i .... ! .... ] .... i .... ! .... i .... ~---~ .... ~ .... : ......... ~ .... ~ .... ~--.~ ........ ,;---~ .... i ...... ~ .... i---~ ......... ,;--.~ .... i ........ ~ .... ~--.i
.... ! .... ~ .... ~ ......... :! .... :=: .... !: ........ i: .... i: .... ::= ......... :i .... ,,:: .... i: .... I---i,, .... :ii,, ......... i---!= ,, .... i= ......... i: .... i---i: : ......... ~!i,, .... ~i .... i~ .... ~'~ ....
34ms 38ms 42ms
(c)
4(;ms
time
50ms
FIGURE 1.10 (continued) (c) Voltage notching caused by a three-phase rectifier with interphase reactor for a firing angle
of a = 0 ~ result of PSpice simulation. Waveshapes with notches: line-to-line voltages of rectifier, Vab and Va'b being the line-
to-line voltages of the two voltage systems; sinusoidal waveshape: line-to-line voltage of infinite bus.
FIGURE 1.11 Measured current wave shape of state-of-the-art personal computer (PC) (many periods) [45].
Interharmonics. Interharmonics are discussed in
Section 1.4.1. Their frequencies are not integer mul-
tiples of the fundamental frequency.
Notching. A periodic voltage disturbance caused
by line-commutated thyristor circuits is called notch-
ing. The notching appears in the line voltage wave-
form during normal operation of power electronic
devices when the current commutates from one
phase to another. During this notching period, there
exists a momentary short-circuit between the two
commutating phases, reducing the line voltage; the
voltage reduction is limited only by the system
impedance.
Notching is repetitive and can be characterized by
its frequency spectrum (Figs. 1.10b,c). The frequency
of this spectrum is quite high. Usually it is not possi-
ble to measure it with equipment normally used for
harmonic analysis. Notches can impose extra stress
on the insulation of transformers, generators, and
sensitive measuring equipment.
Notching can be characterized by the following
properties:

18. 12 CHAPTER 1
A
Q.
mO
t~
0
>
I ! I
0 50 100 150
FIGURE 1.12 Voltage flicker caused by arc furnace operation.
J
time (ms)
200
9 Notch depth: average depth of the line voltage
notch from the sinusoidal waveform at the funda-
mental frequency;
9 Notch width: the duration of the commutation
process;
9 Notch area: the product of notch depth and width;
and
9 Notch position: where the notch occurs on the
sinusoidal waveform.
Some standards (e.g., IEEE-519) set limits for notch
depth and duration (with respect to the system
impedance and load current) in terms of the notch
depth, the total harmonic distortion THDv of supply
voltage, and the notch area for different supply
systems.
Electric Noise. Electric noise is defined as unwanted
electrical signals with broadband spectral content
lower than 200 kHz [37] superimposed on the power
system voltage or current in phase conductors, or
found on neutral conductors or signal lines. Electric
noise may result from faulty connections in transmis-
sion or distribution systems, arc furnaces, electrical
furnaces, power electronic devices, control circuits,
welding equipment, loads with solid-state rectifiers,
improper grounding, turning off capacitor banks,
adjustable-speed drives, corona, and broadband
power line (BPL) communication circuits. The
problem can be mitigated by using filters, line
conditioners, and dedicated lines or transformers.
Electric noise impacts electronic devices such as
microcomputers and programmable controllers.
1.3.6 Voltage Fluctuation and Flicker
Voltage fluctuations are systemic variations of the
voltage envelope or random voltage changes, the
magnitude of which does not normally exceed speci-
fied voltage ranges (e.g., 0.9 to 1.1 pu as defined by
ANSI C84.1-1982) [38]. Voltage fluctuations are
divided into two categories:
9 step-voltage changes, regular or irregular in time,
and
9 cyclic or random voltage changes produced by
variations in the load impedances.
Voltage fluctuations degrade the performance
of the equipment and cause instability of the in-
ternal voltages and currents of electronic equip-
ment. However, voltage fluctuations less than
10% do not affect electronic equipment. The main
causes of voltage fluctuation are pulsed-power
output, resistance welders, start-up of drives, arc fur-
naces, drives with rapidly changing loads, and rolling
mills.
Ricker. Flicker (Fig. 1.12) has been described as
"continuous and rapid variations in the load current
magnitude which causes voltage variations." The
term flicker is derived from the impact of the voltage
fluctuation on lamps such that they are perceived to
flicker by the human eye. This may be caused by an
arc furnace, one of the most common causes of the
voltage fluctuations in utility transmission and distri-
bution systems.
1.3.7 Power-Frequency Variations
The deviation of the power system fundamental fre-
quency from its specified nominal value (e.g., 50 or
60 Hz) is defined as power frequency variation [39].
If the balance between generation and demand
(load) is not maintained, the frequency of the power
system will deviate because of changes in the rota-
tional speed of electromechanical generators. The
amount of deviation and its duration of the fre-
quency depend on the load characteristics and
response of the generation control system to load
changes. Faults of the power transmission system can

19. Introduction to Power Quality 13
also cause frequency variations outside of the
accepted range for normal steady-state operation of
the power system.
1.4 FORMULATIONS AND MEASURES
USED FOR POWER QUALITY
This section briefly introduces some of the most
commonly used formulations and measures of elec-
tric power quality as used in this book and as de-
fined in standard documents. Main sources for power
quality terminologies are IEEE Std 100 [40], IEC
Std 61000-1-1, and CENELEC Std EN 50160 [41].
Appendix C of reference [11] presents a fine survey
of power quality definitions.
1.4.1 Harmonics
Nonsinusoidal current and voltage waveforms (Figs.
1.13 to 1.20) occur in today's power systems due to
equipment with nonlinear characteristics such as
transformers, rotating electric machines, FACTS
devices, power electronics components (e.g., rectifi-
ers, triacs, thyristors, and diodes with capacitor
smoothing, which are used extensively in PCs, audio,
and video equipment), switch-mode power supplies,
compact fluorescent lamps, induction furnaces,
adjustable AC and DC drives, arc furnaces, welding
tools, renewable energy sources, and HVDC net-
works. The main effects of harmonics are malopera-
tion of control devices, telephone interferences,
additional line losses (at fundamental and harmonic
frequencies), and decreased lifetime and increased
losses in utility equipment (e.g., transformers, rotat-
ing machines, and capacitor banks) and customer
devices.
The periodic nonsinusoidal waveforms can be for-
mulated in terms of Fourier series. Each term in the
Fourier series is called the harmonic component of
the distorted waveform. The frequency of harmonics
are integer multiples of the fundamental frequency.
Therefore, nonsinusoidal voltage and current wave-
forms can be defined as
v(t) = Voc + ~ Vr~ cos(hcoot + ah)
h=l
= Voc + vr vr + v(3)(t) + V(4)(t) + ...... ,
(1-1a)
n
i(t) = IDC + ~ Ir(~ cos(h~Oot + ~h)
h=l
= Ioc + i(1)(t) + i (2)(t) + i(3)(t) + i(4)(t) + ...... ,
(1-1b)
where C0o is the fundamental frequency, h is the har-
monic order, and V ~h), /~h), ah, and /3h are the rms
amplitude values and phase shifts of voltage and
current for the hth harmonic.
input
current
output current
output
voltage
input
I v i I i
90 180 270 360
angle (degrees)
FIG U R E 1.13 Measured wave shapes of single-phase induction motor fed by thyristor/triac controller at rated operation
[42].

20. I b
C
_" t
Vac
!
0 180 270 360
angle (degrees)
FIGURE 1.14 Measured wave shapes of three-phase induction motor fed by thyristor/triac controller at rated operation
[42].
14 CHAPTER 1
FIGURE 1.15 Measured wave shapes of 4.5 kVA three-
phase transformer feeding full-wave rectifier [43].
Even and odd harmonics of a nonsinusoidal func-
tion correspond to even (e.g., 2, 4, 6, 8 .... ) and odd
(e.g., 3, 5, 7, 9 .... ) components of its Fourier series.
Harmonics of order 1 and 0 are assigned to the fun-
damental frequency and the DC component of the
waveform, respectively. When both positive and
negative half-cycles of the waveform have identical
shapes, the wave shape has half-wave symmetry and
the Fourier series contains only odd harmonics. This
is the usual case with voltages and currents of power
systems. The presence of even harmonics is often a
clue that there is something wrong (e.g., imperfect
gating of electronic switches [42]), either with the
load equipment or with the transducer used to make
the measurement. There are notable exceptions to
this such as half-wave rectifiers, arc furnaces (with
random arcs), and the presence of GICs in power
systems [27].
Triplen Harmonics. Triplen harmonics (Fig. 1.21) are
the odd multiples of the third harmonic
(h=3, 9, 15, 21,...). These harmonic orders
become an important issue for grounded-wye
systems with current flowing in the neutral line of a
wye configuration. Two typical problems are over-
loading of the neutral conductor and telephone
interference.
For a system of perfectly balanced three-phase
nonsinusoidal loads, fundamental current compo-
nents in the neutral are zero. The third harmonic
neutral currents are three times the third-harmonic
phase currents because they coincide in phase or
time.
Transformer winding connections have a signifi-
cant impact on the flow of triplen harmonic currents
caused by three-phase nonlinear loads. For the
grounded wye-delta transformer, the triplen har-
monic currents enter the wye side and since they are
in phase, they add in the neutral. The delta winding
provides ampere-turn balance so that they can flow
in the delta, but they remain trapped in the delta and
are absent in the line currents of the delta side of the
transformer. This type of transformer connection is
the most commonly employed in utility distribution
substations with the delta winding connected to the
transmission feeder. Using grounded-wye windings
on both sides of the transformer allows balanced
triplen harmonics to flow unimpeded from the low-
voltage system to the high-voltage system. They will
be present in equal proportion on both sides of a
transformer.

21. Introduction to Power Quality 15
A
C
==
L
0
50-
0 V ql',~-'"
- 50 .......
"'4 N
r f
A
/
14.33 16.33 18.33
time (ms)
FIGURE 1.16 Calculated current of brushless DC motor in full-on mode at rated operation [29].
PWM
50 -
motor current
A
er
t9
w-
l
= , ..... - ............ ,.,,..,...
SO
1 - -n i
14.85 16.97
time (ms)
FIGURE 1.17 Calculated current of brushless DC motor in PWM mode at rated operation [29].
FIGURE 1.18 Measured wave shapes of 15 kVA three-
phase transformer feeding resonant rectifier [43].
FIGURE 1.19 Measured wave shapes of 15 kVA three-
phase transformer fed by PWM inverter [43].

22. 16 CHAPTER 1
....
/
V -
I1_ ,,,Ik
. J
\,/
9 ,
(a)
100
80
-o 60
:3
,m
Q.
E 411
m
20
0 1 2 3 4 5 6 7 8 9 10 11 12 13
harmonic order
(b)
FIGURE 1.20 (a) Measured current and (b) measured current spectrum of 20 kW/25 kVA wind-power plant supplying
power via inverter into the 240 V three-phase distribution system at rated load [44].
....................... ! ..............................
, .~. ,
-. f .
.2,..
..... i ...................
"T"
i! "
.... 9 ~i~ ''
i!i i
FIGURE 1.21 Input current to personal computer with dominant third harmonic [45].

23. Introduction to Power Quality 17
Subharmonics. Subharmonics have frequencies
below the fundamental frequency. There are rarely
subharmonics in power systems. However, due to
the fast control of electronic power supplies of com-
puters, inter- and subharmonics are generated in the
input current (Fig. 1.11) [45]. Resonance between
the harmonic currents or voltages with the power
system (series) capacitance and inductance may
cause subharmonics, called subsynchronous reso-
nance [46]. They may be generated when a system is
highly inductive (such as an arc furnace during start-
up) or when the power system contains large capaci-
tor banks for power factor correction or filtering.
Interharmonics. The frequency of interharmonics
are not integer multiples of the fundamental
frequency. Interharmonics appear as discrete fre-
quencies or as a band spectrum. Main sources of
interharmonic waveforms are static frequency con-
verters, cycloconverters, induction motors, arcing
devices, and computers. Interharmonics cause flicker,
low-frequency torques [32], additional temperature
rise in induction machines [33, 34], and malfunction-
ing of protective (under-frequency) relays [35].
Interharmonics have been included in a number of
guidelines such as the IEC 61000-4-7 [36] and the
IEEE-519. However, many important related issues,
such as the range of frequencies, should be addressed
in revised guidelines.
Characteristic and Uncharacteristic Harmonics. The
harmonics of orders 12k + 1 (positive sequence) and
12k- 1 (negative sequence) are called characteristic
and uncharacteristic harmonics, respectively. The
amplitudes of these harmonics are inversely propor-
tional to the harmonic order. Filters are used to
reduce characteristic harmonics of large power con-
verters. When the AC system is weak [47] and the
operation is not perfectly symmetrical, uncharacter-
istic harmonics appear. It is not economical to reduce
uncharacteristic harmonics with filters; therefore,
even a small injection of these harmonic currents
can, via parallel resonant conditions, produce very
large voltage distortion levels.
Positive-, Negative-, and Zero-Sequence Harmonics
[48]. Assuming a positive-phase (abc) sequence bal-
anced three-phase power system, the expressions for
the fundamental currents are
ia(t) --/(a 1 ) COS( COo t)
ib(t) =/~1) COS(COot-- 120 ~
it(t) =/(c 1) COS(COot-- 240~
(1-2)
The negative displacement angles indicate that the
fundamental phasors rotate clockwise in the space-
time plane.
For the third harmonic (zero-sequence) currents,
i(a3)(t) = /(a 3) COS(3COot)
i~3)(t) =/~3) COS 3(coot- 120 ~
= ~3) COS(3COot- 360 ~ = ~3) COS(3COot)
i~3)(t) =/(c 3) COS 3(C0ot- 240 ~
= ~3) COS(3COot- 720 ~ =/(c 3) COS(3COot).
(1-3)
This equation shows that the third harmonic
phasors are in phase and have zero displacement
angles between them. The third harmonic currents
are known as zero-sequence harmonics.
The expressions for the fifth harmonic currents
are
i(aS)(t) =/taS) COS(5COot)
i~5)(t) = I~ 5) COS 5(coot- 120 ~ = I~ 5) COS(5COot- 600 ~
= I~ 5) COS(5COot- 240 ~ = I~ 5) COS(5COot + 120 ~
i~5)(t) =/(c 5) COS 5(coot- 240 ~ =/(c 5) COS(5 coot- 1200 ~
=/(c 5) COS(5COot- 120 ~ = ~5) COS(5COot + 240~
(1-4)
Note that displacement angles are positive; there-
fore, the phase sequence of this harmonic is counter-
clockwise and opposite to that of the fundamental.
The fifth harmonic currents are known as negative-
sequence harmonics.
Similar relationships exist for other harmonic
orders. Table 1.3 categorizes power system harmon-
ics in terms of their respective frequencies and
SOUrCeS.
Note that although the harmonic phase-shift angle
has the effect of altering the shape of the composite
waveform (e.g., adding a third harmonic component
with 0 degree phase shift to the fundamental results
in a composite waveform with maximum peak-to-
peak value whereas a 180 degree phase shift will
result in a composite waveform with minimum peak-
to-peak value), the phase-sequence order of the har-
monics is not affected. Not all voltage and current
systems can be decomposed into positive-, negative-,
and zero-sequence systems [49].
Time and Spatial (Space) Harmonics. Time harmon-
ics are the harmonics in the voltage and current
waveforms of electric machines and power systems
due to magnetic core saturation, presence of nonlin-
ear loads, and irregular system conditions (e.g., faults
and imbalance). Spatial (space) harmonics are
referred to the harmonics in the flux linkage of rotat-
ing electromagnetic devices such as induction and

24. 18 CHAPTER 1
TAB L E 1.3 Types and Sources of Power System Harmonics
Type Frequency Source
DC 0
Odd harmonics
Even harmonics
Triplen harmonics
Positive-sequence harmonics
Negative-sequence harmonics
Zero-sequence harmonics
Time harmonics
Spatial harmonics
Interharmonic
Subharmonic
Characteristic harmonic
Uncharacteristic harmonic
h. 3~ (h = odd)
h. fl (h = even)
3h. f~ (h = 1, 2, 3, 4 .... )
h. f~ (h = 1, 4, 7, 10 .... )
h.f~ (h=2, 5, 8, 11 .... )
h-fl (h = 3, 6, 9, 12 .... )
(same as triplen harmonics)
h. fl (h - an integer)
h. f~ (h = an integer)
h. fa (h = not an integer multiple of fl)
h. fl (h < 1 and not an integer multiple of
j], e.g., h = 15 Hz, 30 Hz)
(12k + 1)"fl (k = integer)
(12k- 1).fl (k = integer)
Electronic switching devices, half-wave rectifiers,
arc furnaces (with random arcs), geomagnetic
induced currents (GICs)
Nonlinear loads and devices
Half-wave rectifiers, geomagnetic induced
currents (GICs)
Unbalanced three-phase load, electronic switching
devices
Operation of power system with nonlinear loads
Operation of power system with nonlinear loads
Unbalanced operation of power system
Voltage and current source inverters, pulse-width-
modulated rectifiers, switch-mode rectifiers and
inverters
Induction machines
Static frequency converters, cycloconverters,
induction machines, arcing devices, computers
Fast control of power supplies, subsynchronous
resonances, large capacitor banks in highly
inductive systems, induction machines
Rectifiers, inverters
Weak and unsymmetrical AC systems
synchronous machines. The main cause of spatial
harmonics is the unsymmetrical physical structure of
stator and rotor magnetic circuits (e.g., selection of
number of slots and rotor eccentricity). Spatial har-
monics of flux linkages will induce time harmonic
voltages in the rotor and stator circuits that generate
time harmonic currents.
1.4.2 The Average Value of a
Nonsinusoidal Waveform
The average value of a sinusoidal waveform is
defined as
i T
Iave=~!i(t)dt. (1-5)
For the nonsinusoidal current of Eq. 1-1,
T
1 !i(t)dt lay e = -~
T
= l ![i(1)(t) + i(2)(t) + i(3)(t) + i(4)(t) + ..... ]dt.
(1-6)
Since all harmonics are sinusoids, the average value
of a nonsinusoidal function is equal to its DC
value:
1.4.3 The rms Value of a
Nonsinusoidal Waveform
The rms value of a sinusoidal waveform is defined
as
9 ]lr~i2(t) I-~ !
Irm s = dt = I2ax cos2(okt)dt
,]112 _ Imax
-- "2 max-- ~/~" ~/
(1-8)
For the nonsinusoidal current of Eq. 1-1,
Irms = Ii2(t)dt
0
- ~ -t 1 ![I~l:x COS(0k/+ ill)* '(m2a)x COS(2okt + f12)
t" T
cos(3okt + 133) +...]2dt} 1/2
T(3)
lmax
J
t'! 1,,2 - T [ (/max c~
+ (I~m2a~) 2 COS2( 2c0/+/~2)
+ (I(m3)x) 2 cos2(3okt +/33)+... + 2I~mla)x .
I~a)x COS(Okt + ill) COS(2Okt + f12) +...]dt} 1/2.
Iave--'IDc. (1-7) (1-9)

25. Introduction to Power Quality 19
This equation contains two parts:
9 The first part is the sum of the squares of
harmonics:
H
~ (I(rnPa)x) 2 COS2 (pO)t + tip). (1-10)
p=l
9 The second part is the sum of the products of
harmonics:
H H
E/max/max cos(pot + flq), p q. E (P) (q) flp)COS(qtot + :1:
p=lq=l
(1-11)
After some simplifications it can be shown that the
average of the second part is zero, and the first part
becomes
I~m,= (I(mPa) cosi(prOt + tip) d(2(.ot)
0 Lp =1
2x
= I [(/(ml~x)2 cos((.0t + fll)]d((_ot)
0
+ /max(2) )2 cos(2r.ot + ~2 d(2ogt)+ ....
I_0
(1-12)
Therefore, the rms value of a nonsinusoidal wave-
form is
Irm s --[([(rlm)s) 2 + (/(r2m)s) 2 -t- (/(r3m)s) 2 +...-'1- (/(rHm~))2] 1,2. (1-13)
If the nonsinusoidal waveform contains DC values,
then
{/(1) "~2 /'](2) "~2 /'/(3) '~2 /'/(H)]211/2
Irms = [IDc "1- .... ), "+" \*rmsl q- .... ), -I- . . . "l- .... )' .I 9
(1-14)
1.4.4 Form Factor (FF)
The form factor (FF) is a measure of the shape of
the waveform and is defined as
FF = Irms . (1-15)
Iave
Since the average value of a sinusoid is zero, its
average over one half-cycle is used in the above
equation. As the harmonic content of the waveform
increases, its FF will also increase.
1.4.5 Ripple Factor (RF)
Ripple factor (RF) is a measure of the ripple content
of the waveform and is defined as
RF = IAc (1-16)
Io c '
where IAC=~/(Ir~)2--(Ioc) 2 . It is easy to show
that
RF=4(Ir~)2-(IDc) 2 =,/(Ir~) 2
I,,~ ~(I,,~) ~
= ~[FF 2-1.
(6,~) 2
(Ioc) 2
(1-17)
1.4.6 Harmonic Factor (HF)
The harmonic factor (HF) of the hth harmonic,
which is a measure of the individual harmonic con-
tribution, is defined as
HFh= I~hm~ (1-18)
I~"
Some references [8] call HF the individual harmonic
distortion (IHD).
1.4.7 Lowest Order Harmonic (LOH)
The lowest order harmonic (LOH) is that harmonic
component whose frequency is closest to that of the
fundamental and its amplitude is greater than or
equal to 3% of the fundamental component.
1.4.8 Total Harmonic Distortion (THD)
The most common harmonic index used to indicate
the harmonic content of a distorted waveform with
a single number is the total harmonic distortion
(THD). It is a measure of the effective value of the
harmonic components of a distorted waveform,
which is defined as the rms of the harmonics
expressed in percentage of the fundamental (e.g.,
current) component:
THDi=I~=2 (I(h))2
1(1) . (1-19)
A commonly cited value of 5 % is often used as a
dividing line between a high and low distortion level.
The ANSI standard recommends truncation of THD
series at 5 kHz, but most practical commercially
available instruments are limited to about 1.6 kHz
(due to the limited bandwidth of potential and
current transformers and the word length of the
digital hardware [5]).
Main advantages of THD are
9 It is commonly used for a quick measure of distor-
tion; and
9 It can be easily calculated.

26. 20 CHAPTER 1
Some disadvantages of THD are
9 It does not provide amplitude information; and
9 The detailed information of the spectrum is lost.
THDi is related to the rms value of the current
waveform as follows [6]:
Irms= l~=Z(I(h))2 = I(1)41+ THD2 i . (1-20)
THD can be weighted to indicate the amplitude
stress on various system devices. The weighted dis-
tortion factor adapted to inductance is an approxi-
mate measure for the additional thermal stress of
inductances of coils and induction motors [9, Table
2.4]:
THD adapted to inductance = THDin d
_ h a
-- ~V.(1) ' (1-21)
where a = 1... 2. On the other hand, the weighted
THD adapted to capacitors is an approximate
measure for the additional thermal stress of capaci-
tors directly connected to the system without series
inductance [9, Table 2.4]:
THD adapted to capacitor = THDca p
V(1)
(1-22)
Because voltage distortions are maintained small,
the voltage THDv nearly always assumes values
which are not a threat to the power system. This is
not the case for current; a small current may have a
high THDi but may not be a significant threat to the
system.
1.4.9 Total Interharmonic Distortion (TIHD)
This factor is equivalent to the (e.g., current) THDi,
but is defined for interharmonics as [9]
TIHD=Ink~=I (I(~'))2
i(1)
(1-23)
where k is the total number of interharmonics and n
is the total number of frequency bins present includ-
ing subharmonics (e.g., interharmonic frequencies
that are less than the fundamental frequency).
1.4.10 Total Subharmonic Distortion (TSHD)
This factor is equivalent to the (e.g., current) THDi,
but defined for subharmonics [9]:
TSHD=Iss~_I (I(s))2
i(1)
(1-24)
where s is the total number of frequency bins present
below the fundamental frequency.
1.4.11 Total Demand Distortion (TDD)
Due to the mentioned disadvantages of THD, some
standards (e.g., IEEE-519) have defined the total
demand distortion factor. This term is similar to
THD except that the distortion is expressed as a
percentage of some rated or maximum value (e.g.,
load current magnitude), rather than as a percentage
of the fundamental current:
TDD = Ih'~=2(I(h) )
/rated
(1-25)
1.4.12 Telephone Influence Factor (TIF)
The telephone influence factor (TIF), which was
jointly proposed by Bell Telephone Systems (BTS)
and the Edison Electric Institute (EEI) and is widely
used in the United States and Canada, determines
the influence of power systems harmonics on tele-
communication systems. It is a variation of THD in
which the root of the sum of the squares is weighted
using factors (weights) that reflect the response of
the human ear [5]:
TIF_I~=I (wiV(i))2_
I/=~l (v(i)) 2
(1-26)
where w/are the TIF weighting factors obtained by
physiological and audio tests, as listed in Table 1.4.
They also incorporate the way current in a power
circuit induces voltage in an adjacent communication
system.
1.4.13 C-Message Weights
The C-message weighted index is very similar to the
TIF except that the weights c/are used in place of w/
[5]:

27. Introduction to Power Quality 21
TABLE 1.4 Telephone Interface (wi) and C-Message (ci) Weighting Factors [5]
i
Harmonic order
Harmonic order (h, fl = 60 Hz) TIF weights (wi) C weights (ci) (h, fl -- 60 Hz)
1 0.5
2 10.0
3 30.0
4 105
5 225
6 400
7 650
8 95O
9 1320
10 1790
11 2260
12 2760
13 3360
14 3830
15 4350
16 4690
17 5100
18 5400
19 5630
20 5860
21 6050
22 6230
23 6370
24 6650
25 6680
26 6790
27 6970
28 7060
|m
0.0017
0.0167
0.0333
O.0875
0.1500
0.222
0.310
0.396
0.489
0.597
0.685
0.767
0.862
0.912
0.967
0.977
1.000
1.000
0.988
0.977
0.960
0.944
0.923
0.924
0.891
0.871
0.860
0.840
TIF weights (Wi) C weights (c;)
29 7320 0.841
30 7570 0.841
31 7820 0.841
32 8070 0.841
33 8330 0.841
34 8580 0.841
35 8830 0.841
36 9080 0.841
37 9330 0.841
38 9590 0.841
39 9840 0.841
40 10090 0.841
41 10340 0.841
42 10480 0.832
43 10600 0.822
44 10610 0.804
45 10480 0.776
46 10350 0.750
47 10210 0.724
48 9960 0.692
49 9820 0.668
50 9670 0.645
55 8090 0.490
60 6460 0.359
65 4400 0.226
70 3000 0.143
75 1830 0.0812
C = I~=l(ciI(i))2 = I~=1(r
I/__~1 (I(i)) 2 Irms
(1-27)
where r are the C-message weighting factors
(Table 1.4) that are related to the TIF weights by
Wi = 5(i)OCo)Ci 9 The C-message could also be applied
to the bus voltage.
1.4.14 V. T and I. T Products
The THD index does not provide information about
the amplitude of voltage (or current); therefore, BTS
or the EEl use I. T and V. T products. The I. T and
V-T products are alternative indices to the THD
incorporating voltage or current amplitudes:
g.T = I~=l(wig(i))2, (1-28)
I'T: J~=l(WiI(i))2,
where the weights wi are listed in Table 1.4.
(1-29)
1.4.15 Telephone Form Factor (TFF)
Two weighting systems widely used by industry for
interference on telecommunication system are [9]
9 the sophomoric weighting system proposed by the
International Consultation Commission on Tele-
phone and Telegraph System (CCITT) used in
Europe, and
9 the C-message weighting system proposed jointly
by Bell Telephone Systems (BTS) and the Edison
Electric Institute (EEl), used in the United States
and Canada.
These concepts acknowledge that the harmonic
effect is not uniform over the audio-frequency range
and use measured weighting factors to account for

28. 22 CHAPTER 1
this nonuniformity. They take into account the type
of telephone equipment and the sensitivity of the
human ear to provide a reasonable indication of the
interference from each harmonic9
The BTS and EEI systems describe the level of
harmonic interference in terms of the telephone
influence factor (Eq. 1-26) or the C-message (Eq.
1-27), whereas the CCITT system uses the telephone
form factor (TFF):
l I~=lKhPh(V(h))2 TFF = -~ (1-30)
where Kh = h/800 is a coupling factor and Ph is the
harmonic weight [9 (Fig. 2.5)] divided by 1000.
1.4.16 Distortion Index (DIN)
The distortion index (DIN) is commonly used in
standards and specifications outside North America.
It is also used in Canada and is defined as [5]
oIg=I~=2 (V(i))2
I/__~l (v(i)) 2
THD
4THD 2 + 1
(1-31)
For low levels of harmonics, a Taylor series expan-
sion can be applied to show
1 THD) DIN = THD(1 - -~ . (1-32)
1.4.17 Distortion Power (D)
Harmonic distortion complicates the computation of
power and power factors because voltage and current
equations (and their products) contain harmonic
components. Under sinusoidal conditions, there are
four standard quantities associated with power:
9 Fundamental apparent power ($1) is the product
of the rms fundamental voltage and current;
9 Fundamental active power (P1) is the average rate
of delivery of energy;
9 Fundamental reactive power (Qa) is the portion of
the apparent power that is oscillatory; and
9 Power factor at fundamental frequency (or dis-
placement factor) cos 01 = P1/S1.
The relationship between these quantities is defined
by the power triangle:
(51) 2--- (P1) 2 + (Q1) 2. (1-33)
If voltage and current waveforms are nonsinusoi-
dal (Eq. 1-1), the above equation does not hold
because S contains cross terms in the products of the
Fourier series that correspond to voltages and cur-
rents of different frequencies, whereas P and Q
correspond to voltages and currents of the same fre-
quency. It has been suggested to account for these
cross terms as follows [5, 50, 51]:
$2= p2 + Q2 + D 2, (1-34)
where
Apparent power = S = Vrmslrm s
= h=0,1,2,3 ..... 0,1,2,3 .... ( Irms ) '
(1-35)
Total real power = P =
where Oh=ah--flh ,
H
Z (h) (h)
Vr~ Irm s COS(0h) ,
h=0,1,2,3 ....
(1-36)
Total reactive power = Q =
H
(h) (h)
Vr~IrmsSin(Oh),
h=0,1,2,3 ....
(1-37)
H-1 H
Distortion power = D = Z Z [(V~ms(m))2 (irms)(n) 2
m=On=m+l
2 (m) 2 (rn) (n)
+ Vr(2) (Irms) COS(0 m 9 -- 2V;2 Irm s --On)]
(1-38)
Also, the fundamental power factor (displacement
factor) in the case of sinusoidal voltage and nonsinu-
soidal currents is defined as [8]
PI
= , (1-39)
COS01 4(P1)2 + (Q1) 2
and the harmonic displacement factor is defined as
[8]
;t= Pi
9 (1-40)
4(Pl )2 + (Q1)2 + D 2
The power and displacement factor quantities
are shown in addition to the power quantities in
Fig. 1.22. A detailed comparison of various defini-
tions of the distortion power D is given in reference
[51].

29. Introduction to Power Quality 23
S D
I Q1
FIGURE 1.22 Phasor diagram of different parameters of electric power under nonsinusoidal conditions.
Vca
R3
Vbc
Lsyst Rsyst
Th /G1 42_ Th:
i a = ] +
V ab 1 V AB
VCA
Lsyst Rsyst _.
Lsyst Rsyst
Xi4
TG3+ Th 5T~G==~S
VBC
ic - - -
+
Ls Ls
source
r ~ ---]
Th4 Ii ~~c4+ I__..I
L _
II
Th 2
Ls
I
Lf
iload
Cf ~ Rload
Vload
I I II I
controlled rectifier ter load
FIG U R E E 1.1.1 Controlled three-phase, full-wave thyristor rectifier.
1.4.18 Application Example 1.1: Calculation
of Input/Output Currents and Voltages of a
Three-Phase Thyristor Rectifier
The circuit of Fig. EI.I.1 represents a phase-
controlled, three-phase thyristor rectifier. The bal-
anced input line-to-line voltages are Yah ='~]-2 240
sin r Vbc = ~r~ 240 sin(c0t- 120~ and ];ca -- ~ 240
sin(~- 240~ where c0 = 2nf and f= 60 Hz. Each of
the six thyristors can be modeled by a self-commu-
tated electronic switch and a diode in series, as is
illustrated in Fig. El.l.2. Use the following PSpice
models for the MOSFET and the diode:
9 Model for self-commutated electronic switch
(MOSFET):
.model SMM NMOS(Level-3 Gamma-0
Delta = 0 Eta = 0 Theta = 0 Kappa = 0 Vmax = 0
i ..... thyr--istor ..... i
I ............. I
I I self-commutated I I I I
I I electronic switchl Idiodel I
II I I I I
_11 1 r~ _ I I I ~,a I I_
I _ ~ | Cthyristor
Athyrist~ I ~11 --s IIAII IICI
II -I-VCs I I I I
It I "2 II I I I
II G I I I
I I._____ th]~ist-~ .]-- ----I I
I ............... I
FIGURE E1.1.2 Model for thyristor consisting of self-
commuted switch and diode.
+ XJ = 0 TOX = 100 N UO = 600 PHI = 0.6 RS =
42.69 in KP = 20.87 u L = 2 u
+ W = 2.9 VTO = 3.487 RD = 0.19 CBD = 200 N
PB = 0.8 MJ = 0.5 CGSO = 3.5 n
+ CGDO = 100 p RG = 1.2 IS = 10 F)

30. 24 CHAPTER 1
9 Model for diode:
.model D1N4001 D(IS = 10 -12)
The parameters of the circuit are as follows:
9 System resistance and inductance Lsyst = 300/zH,
Rsyst = 0.05 ~-~;
9 Load resistance Rload = 10 f~;
9 Filter capacitance and inductance Cy=500gF,
LI= 1 mH;
9 Snubber inductance Ls = 5 nil;
Note that R3 must be nonzero because PSpice cannot
accept three voltage sources connected within a
loop.
Perform a PSpice analysis plotting input line-to-
line voltages Vab , Vbc , Vca , VAB , VBC , ];CA , input currents
ia, io, ic, and the rectified output voltage Vloaa and
output current/load for a = 0 ~ during the time interval
0 < t < 60 ms. Print the input program. Repeat the
computation for a = 50 ~ and a = 150 ~
1.4.19 Application Example 1.2" Calculation
of Input/Output Currents and Voltages of a
Three-Phase Rectifier with One Self-
Commutated Electronic Switch
An inexpensive and popular rectifier is illustrated in
Fig. El.2.1. It consists of four diodes and one self-
commutated electronic switch operated at, for
example, fswitch -- 600 HZ. The balanced input line-to-
line voltages are Vab -- ~]2 240 sin ~, Vbc = ~/2 240
sin(c0t- 120~ and Vc,, = ~ 240 sin(c0t- 240~ where
o9= 2nf and f-60 Hz. Perform a PSpice analysis.
Use the following PSpice models for the MOSFET
and the diodes:
9 Model for self-commutated electronic switch
(MOSFET):
MODEL SMM NMOS(LEVEL = 3 GAMMA = 0
DELTA = 0 ETA = 0 THETA = 0
+ KAPPA = 0 VMAX = 0 XJ = 0 TOX = 100 N
UO = 600 PHI = 0.6 RS = 42.69 M KP = 20.87 U
+ L=2U W=2.9 VTO=3.487 RD=0.19
CBD = 200 N PB = 40.8 MJ = 0.5 CGSO = 3.5 N
+ CGDO = 100 P RG = 1.2 IS = 10 F)
9 Model for diode:
.MODEL D1N4001 D(IS = 10 -12)
The parameters of the circuit are as follows:
9 System resistance and inductance Lsyst = 300 ]./H,
Rsyst = 0.05 ~;
9 Load resistance Rloa0 = 10 ~;
9 Filter capacitance and inductance G=500/zF,
L r = 5 mH; and
9 Snubber inductance L~ = 5 nil.
Note that R3 must be nonzero because PSpice can-
not accept three voltage sources connected within
a loop. The freewheeling diode is required to
reduce the voltage stress on the self-commutated
switch.
Lsyst Rsyst
R 3 ia
Lsyst Rsyst
I b
I Lsyst Rsyst
Vbc
I c
VCA VAB
-- ,
_gx J_.
A I+
li4 VBC
+
D4 ~ D61~ D22~
I II II
source rectifier
T_v ,
Lf
Df2-~
II II
switch free filter
wheeling diode
FIGURE E1.2.1 Three-phase, full-wave rectifier with one self-commutated switch.
cf !
+
iload
Rload
I
Vload
II, I
load

31. Introduction to Power Quality 25
Print the PSpice input program. Perform a PSpice
analysis plotting input line-to-line voltages Vab, Vbc,
Vca, VAB, VBC, VCA, input currents ia, ib, ic, and the recti-
fied output voltage Vload and output current/load for a
duty ratio of 8=50% during the time interval
0 < t < 60 ms.
1.4.20 Application Example 1.3: Calculation
of Input Currents of a Brushless DC Motor in
Full-on Mode (Three-Phase Permanent-Magnet
Motor Fed by a Six-Step Inverter)
In the drive circuit of Fig. E1.3.1 the DC input
voltage is Vz)c = 300 V. The inverter is a six-pulse
or six-step or full-on inverter consisting of six self-
commutated (e.g., MOSFET) switches. The electric
machine is a three-phase permanent-magnet motor
represented by induced voltages (eA, eB, ec), resis-
tances, and leakage inductances (with respect to
stator phase windings) for all three phases. The
induced voltage of the stator winding (phase A) of
the permanent-magnet motor is
eA = 160 sin(rot + O) [V],
where o~= 2nfl and fl = 1500 Hz. Correspondingly,
e8 = 160 sin(ogt + 240 ~ + O) [V],
ec = 160 sin(cot + 120 ~ + O) [V].
The resistance R1 and the leakage inductance Lie
of one of the phases are 0.5f~ and 50~tH,
respectively.
The magnitude of the gating voltages of the six
MOSFETs is VGmax-" 15 V. The gating signals with
their phase sequence are shown in Fig. E1.3.2. Note
that the phase sequence of the induced voltages (ez,
eB, ec) and that of the gating signals (see Fig. E1.3.2)
must be the same. If these phase sequences are not
the same, then no periodic solution for the machine
currents (iMA, iMB, iMC) can be obtained.
The models of the enhancement metal-oxide semi-
conductor field-effect transistors and those of the
(external) freewheeling diodes are as follows:
9 Model for self-commutated electronic switch
(MOSFET):
.MODEL SMM NMOS(LEVEL = 3 GAMMA = 0
DELTA = 0 ETA = 0 THETA = 0
+ KAPPA = 0 VMAX = 0 XJ = 0 TOX = 100 N
UO = 600 PHI = 0.6 RS = 42.69 M KP = 20.87 U
+ L = 2 U W = 2.9 VTO = 3.487 RD = 0.19 CBD =
200 N PB = 0.8 MJ = 0.5 CGSO = 3.5 N
+ CGDO = 100 P RG = 1.2 IS = 10 F)
9 Model for diode:
.MODEL DIN4001 D(IS = 10 -12)
a) Using PSpice, compute and plot the current of
MOSFET QAu (e.g., iOAU) and the motor
current of phase A (e.g., iMZ) for the phase
angles of the induced voltages 0 = 0 ~ 0 = +30 ~
0= +60 ~ 0=-30 ~ and 0=-60 ~ Note that the
gating signal frequency of the MOSFETs cor-
responds to the frequency fl, that is, full-on
mode operation exists. For switching sequence
see Fig. E1.3.2.
f~
DAU
2
C = 100~F
DAL
2
_ "IC=100gF
1 1
iQAU
DBU
QAU QBU
/'.'~ f~+ eA - ,
if
+
' Qcu
Dcu
DBL
"~ ItQAL 2-~ I QBL
ec
iMA
T
-eB
floating +
neutral
Llf 2
QCL
DCL
FIGURE E1.3.1 Circuit of brushless DC motor consisting of DC source, inverter, and permanent-magnet machine.

32. 26 CHAPTER 1
I
I
I
15V ;
Au
T-l/f~
I
I
Bu
I I
I I
Ctj
OVl i i i
' i i i i i i
i i i i i i i
! i i i i i i
! i i i i i i
! i i i i i i
lsv ! i i i i i i
t
BL
OV!
CL AL BL
I I I
9 o 9 . 9 o
FIGURE E1.3.2 Sequence of gating signals for brushless DC motor in six-step (six-pulse) operation.
b) Repeat part a for 0= +30 ~ with reversed phase
sequence.
Note the following:
9 The step size for the numerical solution should be
in the neighborhood of At = 0.05 ~ts; and
9 To eliminate computational transients due to
inconsistent initial conditions compute at least
three periods of all quantities and plot the last
(third) period of iaAu and iMa for all five cases,
where 0 assumes the values given above.
1.4.21 Application Example 1.4: Calculation
of the Efficiency of a Polymer Electrolyte
Membrane (PEM) Fuel Cell Used as Energy
Source for a Variable-Speed Drive
a) Calculate the power efficiency of a PEM fuel
cell.
b) Find the specific power density of this PEM fuel
cell expressed in W/kg.
c) How does this specific power density compare
with that of a lead-acid battery [66]?
Hints:
9 The nominal energy density of hydrogen is
28 kWh/kg, which is significantly larger than that
of gasoline (12.3 kWh/kg). This makes hydrogen a
desirable fuel for automobiles.
9 The mass density of hydrogen is 7,=0.0899 g/
liter.
9 The oxygen atom has 8 electrons, 8 protons, and 8
neutrons.
A PEM fuel cell as specified by [65] has the following
parameters:
Performance:
Fuel:
Operating
environment:
Output power: erat "- 1200 W a
Output current:/rat = 46 A a
DC voltage range: Vra t = 22 to 50 V
Operating lifetime: T~ife = 1500 h b
Composition: C = 99.99% dry gaseous
hydrogen
Supply pressure: p = 10 to 250 PSIG
Consumption: V = 18.5 SLPM c
Ambient temperature: lamb = 3 to 30~
Relative humidity: RH = 0 to 95%
Location: Indoors and outdoors d
Physical: Length x width x height: (56)(25)(33) cm
Mass: W = 13 kg
Emissions: Liquid water: H20 = 0.87 liters maximum
per hour.
"Beginning of life, sea level, rated temperature range.
bCO within the air (which provides the oxygen) destroys the
proton exchange membrane.
CAt rated power output, SLPM - standard liters per minute
(standard flow).
dUnit must be protected from inclement weather, sand, and
dust.
1.4.22 Application Example 1.5: Calculation
of the Currents of a Wind-Power Plant PWM
Inverter Feeding Power into the Power System
The circuit diagram of PWM inverter feeding power
into the 240 VL-L three-phase utility system is shown
in Fig. El.5.1 consisting of DC source, inverter, filter,
and power system. The associated control circuit is
given by a block diagram in Fig. E1.5.2.
Use the PSpice program windpower.cir as listed
below:
*windpower.cir; Is:40Arms,VDC:450V,
phi =30

33. Introduction to Power Quality 27
9 9
V o = 390V
4 ~_~ I5 ~_~ I6 ~
~DF~_~ ~--~ DF3
R N = L N =
] ]3 l I
L w = lmH Rw= 10mr2 r ] iN a
Rf _~ VNa (t) =
196V sin(cot)
~ Cf = 10.3gF
iwb v/~ "~
Rf iNb
Rf = lOm~
~f Lf = 45~tH
v~,
I iN c
I I I I I
inverter output filter system
FIGURE E1.5.1 Current-controlled PWM inverter feeding into utility system.
sine ~176 I H,
F=60 Hz, 3 ~ {""
reference currents
I+STE I" ~"
input fdter
| |
{ urrent
measured
inverter { ,f.$-' T / /// system
f = 1/T = 60Hz
-'-""1 , I I
T
f = h 9 60Hz
oscillator generating
K/triangular (carrier) voltage (#1)
amplifier
I ...+ .....
G = 1 { i/i -~,/ ,-,,,- -
A -A'A,A A A A
V V V ~LV-V~
hysteresis
O gating signals to
,Z/ -~ upper IGBTs
.iJ
fit
-._/"~ .I _~ .... @ gating signals to
G = 1 ~,~-~' .-~, ,Z/ 7 .... lower IGBTs
I
amplifier hysteresis
/x/~/x
f g I g ~
oscillator generating
f = h 9 60Hz triangular (carrier) voltage (#2)
FIGURE E1.5.2 Block diagram of control circuit for current-controlled PWM inverter.

34. 28 CHAPTER 1
VDC supply 2 0 450
***switches
mswl 2 ii i0 i0
dswl i0 2 diode
msw2 2 21 20 20
dswl 20 2 diode
msw3 2 31 30 30
dsw3 30 2 diode
msw4 i0 41 0 0
dsw4 0 i0 diode
msw5 20 51 0 0
dsw5 0 20 diode
msw6 30 61 0 0
dsw6 0 30 diode
*** inductors
Mosfet
Mosfet
Mosfet
Mosfet
Mosfet
Mosfet
L W1 i0 15 im
m
L W2 20 25 im
L_W3 30 35 im
*** resistors or voltage sources
measuring current
R_WI 15 16 10m
R_W2 25 26 10m
R_W3 35 36 10m
***voltages serve as reference
currents
vrefl 12 0 sin(0 56.6 60 0
0)
vref2 22 0 sin(0 56.6 60 0
-120)
vref3 32 0 sin(0 56.6 60 0
-240)
*** voltages derived from load
currents (measured with shunts)
eoutl 13 0 15 16 i00
eout2 23 0 25 26 i00
eoutl 33 0 35 36 i00
*** error signals derived from the
difference between vref and eout
rdiffl 12 13a ik
rdiff2 22 23a ik
rdiff3 32 33a ik
cdiffl 12 13a lu
cdiff2 22 23a lu
cdiff3 32 33a lu
rdiff4 13a 13 ik
rdiff5 23a 23 ik
rdiff6 33a 33 ik
ecinl 14 0 12
ecin2 24 0 22
ecin3 34 0 32
vtriangular 5 0
86.5u 86.5u 0.6u
13a 2
23a 2
33a 2
pulse (-i0
173.6u)
i0
for
*** gating signals for upper
switches (mosfets) as a result
*** of comparison between triangular
voltage and error signals
xgsl 14 5 ii i0 comp
xgs2 24 5 21 20 comp
xgs3 34 5 31 30 comp
*** gating of lower switches
egs4 41 0 poly(1)(Ii,I0) 50 -i
egs5 51 0 poly(1) (21, 20) 50 -i
egs6 61 0 poly(1) (31, 30) 50 -i
*** ~iter removed because of node
limit of
for Spice
I~i 16 15b
i~2 26 25b
in3 36 35b
r~l 15b 15c
r~2 25b 25c
r~3 35b 35c
c~l 15c 26
c~2 25c 36
c~3 35c 16
RMI
LMI 18
Voutl 19
0 -30)
RM2 26 28
LM2 28 29
Vout2 29
0 -150)
RM3 36 38
LM3 38 39
Vout2 39
0 -270)
*** comparator:
.subckt
rin 1
rl 3
e2 4
r2 4
dl 5
d2 2
e3 7
r3 7
c3 8
r4 3
e4 9
.model
.model
.ends
64 for PSpice, not required
45u
45u
45u
0.01
0.01
0.01
10.3u
10.3u
10.3u
representation of utility system
16 18 50m
19 265u
123 sin( 0 196 60 0
50m
265u
123 sin( 0 196 60 0
50m
265u
123 sin( 0 196 60 0
vl-v2, vgs
2 9 i0 comp 1
3 2.8k
2 20meg
2 3 2 50
5 ik
6 zenerdiodel
6 zenerdiode2
2 5 2 1
8 i0
2 10n
8 100k
i0 8 2 1
zenerdiodel D
zenerdiode2 D
comp
(Is:ip BV=0.1)
(Is=ip BV=50)

35. Introduction to Power Quality 29
*** models
.model Mosfet nmos(level=3 gamma=O
kappa:O tox=lOOn rs=42.69m kp=20.87u
l=2u
+ w=2.9 delta=O eta=O theta=O vmax=O
xj=O uo=600 phi=0.6
+ vto=3.487 rd=O.19 cbd=2OOn pb=0.8
mj=0.5 cgso=3.5n cgdo=lOOp rg=l.2
is=lOf)
.model diode d(is=Ip)
***options
.options abstol=O.Olm chgtol= O.Olm
reltol=50m vntol=im itl5=O it14=200
***analysis request
.tran 5u 350m 16.67m 5u
***prepare for plotting
.probe
***final statement
.end
a) Use "reverse" engineering and identify the nodes
of Figs. El.5.1 and E1.5.2, as used in the PSpice
program. It may be advisable that you draw your
own detailed circuit.
b) Study the PSpice program wr.cir. In particular it
is important that you understand the poly state-
ments and the subcircuit for the comparator. You
may ignore the statements for the filter between
switch and inverter (see Fig. El.5.1) if the node
number exceeds the maximum number of 64
(note the student version of the PSpice program
is limited to a maximum of 64 nodes).
c) Run this program with inverter inductance values
of Lw = 1 mH for a DC voltage of Voc = 450 V.
d) Plot the current supplied by the inverter to the
power system and the phase power system's
voltage.
1.5 EFFECTS OF POOR POWER QUALITY
ON POWER SYSTEM DEVICES
Poor electric power quality has many harmful effects
on power system devices and end users. What makes
this phenomenon so insidious is that its effects are
often not known until failure occurs. Therefore,
insight into how disturbances are generated and
interact within a power system and how they affect
components is important for preventing failures.
Even if failures do not occur, poor power quality and
harmonics increase losses and decrease the lifetime
of power system components and end-use devices.
Some of the main detrimental effects of poor power
quality include the following:
9 Harmonics add to the rms and peak value of the
waveform. This means equipment could receive a
damagingly high peak voltage and may be suscep-
tible to failure. High voltage may also force power
system components to operate in the saturation
regions of their characteristics, producing addi-
tional harmonics and disturbances. The waveform
distortion and its effects are very dependent on the
harmonic-phase angles. The rms value can be the
same but depending on the harmonic-phase angles,
the peak value of a certain dependent quantity can
be large [52].
9 There are adverse effects from heating, noise, and
reduced life on capacitors, surge suppressors,
rotating machines, cables and transformers, fuses,
and customers' equipment (ranging from small
clocks to large industrial loads).
9 Utility companies are particularly concerned that
distribution transformers may need to be derated
to avoid premature failure due to overheating
(caused by harmonics).
9 Additional losses of transmission lines, cables,
generators, AC motors, and transformers may
occur due to harmonics (e.g., inter- and subhar-
monics) [53].
9 Failure of power system components and customer
loads may occur due to unpredicted disturbances
such as voltage and/or current magnifications due
to parallel resonance and ferroresonance.
9 Malfunction of controllers and protective devices
such as fuses and relays is possible [35].
9 Interharmonics may occur which can perturb
ripple control signals and can cause flicker at sub-
harmonic levels.
9 Harmonic instability [9] may be caused by large
and unpredicted harmonic sources such as arc
furnaces.
9 Harmonic, subharmonic, and interharmonic
torques may arise [32].
The effects of poor power quality on power
systems and their components as well on end-use
devices will be discussed in detail in subsequent
chapters.
1.6 STANDARDS AND GUIDELINES
REFERRING TO POWER QUALITY
Many documents for control of power quality have
been generated by different organizations and insti-
tutes. These documents come in three levels of appli-
cability and validity: guidelines, recommendations,
and standards [5]:

36. 30 CHAPTER 1
9 Power quality guidelines are illustrations and
exemplary procedures that contain typical param-
eters and representative solutions to commonly
encountered power quality problems;
9 Power quality recommended practices recognize
that there are many solutions to power quality
problems and recommend certain solutions over
others. Any operating limits that are indicated by
recommendations are not required but should be
targets for designs; and
9 Power quality standards are formal agreements
between industry, users, and the government as to
the proper procedure to generate, test, measure,
manufacture, and consume electric power. In
all jurisdictions, violation of standards could be
used as evidence in courts of law for litigation
purposes.
Usually the first passage of a power quality docu-
ment is done in the form of the guidelines that are
often based on an early document from an industry
or government group. Guides are prepared and
edited by different working groups. A recommended
practice is usually an upgrade of guidelines, and a
standard is usually an upgrade of a recommended
practice.
The main reasons for setting guidelines, recom-
mendations, and standards in power systems with
nonsinusoidal voltages or currents are to keep dis-
turbances to user equipment within permissible
limits, to provide uniform terminology and test pro-
cedures for power quality problems, and to provide
a common basis on which a wide range of engineer-
ing is referenced.
There are many standards and related documents
that deal with power quality issues. A frequently
updated list of available documents on power quality
issues will simplify the search for appropriate infor-
mation. Table 1.5 includes some of the commonly
used guides, recommendations, and standards on
electric power quality issues. The mostly adopted
documents are these:
9 The North American Standards adopted by many
countries of North and South America:
a) Institute of Electrical and Electronic Engi-
neering (IEEE).
b) American National Standards Institute
(ANSI).
c) Military Specifications (MIL-Specs) published
by the U.S. Department of Defense and Cana-
dian Electric Association (CEA).
9 British Standards (BS).
9 European (Standards) Norms (EN).
9 International Electrotechnical Commission
(IEC).
9 Computer Business Equipment Manufacturers
Association (CBEMA) curves.
9 Information Technology Industry Council (ITIC)
curves [6 (Fig. 2.13), 9 (Fig. 5.9)].
9 VDE (Verein Deutscher Elektrotechniker) [8,
page 1] of the German association of individuals
and groups concerned with electrotechnics.
9 NEMA [9, page 20] of the U.S. National Electric
Manufacturers Association.
1.6.1 IEC 61000 Series of Standards for
Power Quality
The IEC 61000 (or EN 61000) series [54], one of the
most commonly used references for power quality in
Europe, contains six parts, each with standards and
technical reports [9]:
9 Part 1 (General). Two sections cover application
and interpretation aspects of EMC (electromag-
netic compatibility).
9 Part 2 (Environment). Twelve sections give clas-
sification of the electromagnetic environment and
compatibility levels for different environments.
Some aspects of this document include harmonic
compatibility levels of residential LV (low voltage)
systems (IEC 61000-2-2), industrial plants (IEC
61000-24), and residential MV (medium voltage)
systems (IEC 61000-2-12).
9 Part 3 (Limits). Eleven sections cover emission
limits for harmonics and other disturbances.
Some aspects of this document include harmonic
current emission limits for equipment connected
at LV with low (less than 16 A per phase) current
(IEC 61000-3-2), flicker (IEC 61000-3-3), har-
monic current emission limits for equipment
connected at LV with high (more than 16 A per
phase) current (IEC 61000-3-4), and assessment
of emission limits for distorting loads in MV and
HV (high voltage) power systems (IEC
61000-3-6).
9 Part 4 (Testing and Measurement Techniques).
Thirty-one sections describe standard methods for
testing equipment of emission and immunity to
different disturbances. Some aspects of this docu-
ment include harmonic and interharmonic mea-
surements and instrumentation (IEC 61000-4-7),
dips and interruptions (EN 61000-4-11), interhar-
monics (EN 61000-4-13), and power quality mea-
surement methods (IEC 61000-4-30).
9 Part 5 (Installation and Mitigation Guidelines).
Seven sections cover earthing (grounding), cabling,

37. Introduction to Power Quality 31
TAB L E 1.5 Some Guides, Recommendations, and Standards on Electric Power Quality
Source Coverage
IEEE 4:1995
IEEE 100:1992
IEEE 120:1989
IEEE 141:1993
IEEE 142:1993 (The Green
Book)
IEEE 213:1993
IEEE 241:1990
(The Gray Book)
IEEE 281:1994
IEEE 299:1991
IEEE 367:1996
IEEE 376:1993
IEEE 430:1991
IEEE 446:1987 (The Orange
Book)
IEEE 449:1990
IEEE 465
IEEE 472
IEEE 473:1991
IEEE 493:1997 (The Gold
Book)
IEEE 519:1993
IEEE 539:1990
IEEE 859:1987
IEEE 944:1986
IEEE 998:1996
IEEE 1048:1990
IEEE 1057:1994
IEEE Pll00:1992 (The
Emerald Book)
IEEE 1159:1995
IEEE 1250:1995
IEEE 1346:1998
IEEE P-1453
IEEE/ANSI 18:1980
IEEE/ANSI C37
IEEE/ANSI C50:1982
IEEE/ANSI C57.110:1986
IEEE/ANSI C57.117:1986
IEEE/ANSI C62.45:1992
(IEEE 587)
IEEE/ANSI C62.48" 1995
ANSI C84.1:1982
IEEE and ANSI Documents
Standard techniques for high-voltage testing.
Standard dictionary of electrical and electronic terms.
Master test guide for electrical measurements in power circuits.
Recommended practice for electric power distribution for industrial plants. Effect of voltage
disturbances on equipment within an industrial area.
Recommended practice for grounding of industrial and commercial power systems.
Standard procedure for measuring conducted emissions in the range of 300 kHz to 25 MHz
from television and FM broadcast receivers to power lines.
Recommended practice for electric power systems in commercial buildings.
Standard service conditions for power system communication equipment.
Standard methods of measuring the effectiveness of electromagnetic shielding enclosures.
Recommended practice for determining the electric power station ground potential rise and
induced voltage from a power fault.
Standard for the measurement of impulse strength and impulse bandwidth.
Standard procedures for the measurement of radio noise from overhead power lines and
substations.
Recommended practice for emergency and standby systems for industrial and commercial
applications (e.g., power acceptability curve [5, Fig. 2-26], CBEMA curve).
Standard for ferroresonance voltage regulators.
Test specifications for surge protective devices.
Event recorders.
Recommended practice for an electromagnetic site survey (10 kHz to 10 GHz).
Recommended practice for the design of reliable industrial and commercial power systems.
Recommended practice for harmonic control and reactive compensation of static power
converters.
Standard definitions of terms relating to corona and field effects of overhead power lines.
Standard terms for reporting and analyzing outage occurrences and outage states of electrical
transmission facilities.
Application and testing of uninterruptible power supplies for power generating stations.
Guides for direct lightning strike shielding of substations.
Guides for protective grounding of power lines.
Standards for digitizing waveform recorders.
Recommended practice for powering and grounding sensitive electronic equipment in
commercial and industrial power systems.
Recommended practice on monitoring electric power quality. Categories of power system
electromagnetic phenomena.
Guides for service to equipment sensitive to momentary voltage disturbances.
Recommended practice for evaluating electric power system compatibility with electronics
process equipment.
Flicker.
Standards for shunt power capacitors.
Guides for surge withstand capability (SWC) tests.
Harmonics and noise from synchronous machines.
Recommended practice for establishing transformer capability when supplying nonsinusoidal
load currents.
Guides for reporting failure data for power transformers and shunt reactors on electric utility
power systems.
Recommended practice on surge voltage in low-voltage AC power circuits, including guides for
lightning arresters applications.
Guides on interactions between power system disturbances and surge protective devices.
American national standard for electric power systems and equipment voltage ratings (60 Hz).

38. 32 CHAPTER 1
TAB L E 1.5 Some Guides, Recommendations, and Standards on Electric Power Quality (continued)
Source Coverage
ANSI 70
ANSI 368
ANSI 377
IEC 38:1983
IEC 816:1984
IEC 868:1986
IEC 868-0:1991
IEC 1000-3-2:1994
IEC 1000-3-6:1996
IEC 1000-4:1991
EN 50160:1994
IEC/EN 60868-0
IEC 61000 standards on
EMC
BS5406 (based on IEC 555
part 2)
ER G5/3
G5/4:2001
UIE-DWG-2-92-D
UIE-DWG-3-92-G
CBEMA Curves: 1983
ITI Curves (new CBEMA
Curves)
National electric code.
Telephone influence factor.
Spurious radio frequency emission from mobile communication equipment.
International Electrotechnical Commission (IEC) Documents
Standard voltages.
Guides on methods of measurement of short-duration transients on low-voltage power and
signal lines. Equipment susceptible to transients.
Flicker meter. Functional and design specifications.
Flicker meter. Evaluation of flicker severity. Evaluates the severity of voltage fluctuation on the
light flicker.
Electromagnetic compatibility Part 3: Limits Section 2: Limits for harmonic current emissions
(equipment absorbed current <16 A per phase).
Electromagnetic compatibility Part 3: Limits Section 6: Emission limits evaluation for
perturbing loads connected to MV and HV networks.
Electromagnetic compatibility Part 4: Sampling and metering techniques.
Voltage characteristics of electricity supplied by public distribution systems.
Flicker meter implementation.
Electromagnetic compatibility (EMC).
British Standards (BS) and European Norm Documents
Control harmonic emissions from small domestic equipment.
Other Documents
Basis of standards in some other (mostly commonwealth) countries, but it does not include
notching and burst harmonics.
Limiting harmonic voltage distortion levels on public networks at the time of connection of new
nonlinear loads to ensure compatibility of all connected equipment.
Produced by the Distribution Working Group (DWG) of Union Internationale Electrothermie
(UIE). Includes guides for measurements of voltage dips and short-circuit interruptions
occurring in industrial installations.
UIE guides for quality of electrical supply for industrial installations, including types of
disturbances and relevant standards.
Produced by the Computer Business Equipment Manufacturers Association for the design of
the power supply for computers and electronic equipment.
Information Technology Industry Council (the new name for CBEMA) application.
mitigation, and degrees of protection against EM
(electromagnetic) disturbances.
9 Part 6 (Generic Standards). Five sections cover
immunity and emission standards for residential,
commercial, industrial, and power station
environments.
EN 61000-3-2 [2] introduces power quality limits
(Table 1.6) for four classes of equipment:
9 Class A: Balanced three-phase equipment and all
other equipment, except those listed in other
classes.
9 Class B: Portable tools.
9 Class C: Lighting equipment, including dimming
devices.
9 Class D: Equipment with a "special wave shape"
and an input power of 75 to 600 W.
1.6.2 IEEE-519 Standard
The United States (ANSI and IEEE) do not have
such a comprehensive and complete set of power
quality standards as the IEC. However, their stand-
ards are more practical and provide theoretical back-
ground on the phenomena. This has made them very
useful reference documents, even outside of the
United States. IEEE-Std 519 [1] is the IEEE recom-
mended practices and requirements for harmonic

39. Introduction to Power Quality 33
TABLE 1.6 Harmonic Limits Defined by the EN 61000 Standards for Different Classes of Equipment
Harmonic order (h) Class A (A) Class B (A) Class C (% of fundamental) Class D (% of fundamental)
2 1.08 1.62 2
3 2.30 3.45 30 x ;L* 3.4
4 0.43 0.65
5 1.44 2.16 10 1.9
6 0.30 0.45
7 0.77 1.12 7 1
8 0.23 0.35
9 0.40 0.60 5 0.5
10 0.18 0.28
11 0.33 0.50 3 0.35
12 0.15 0.23
13 0.21 0.32 3 0.296
14-40 (even) 1.84/h 2.76/h
15-39 (odd) 2.25/h 3.338/h 3 3.85/h
*;L is the circuit power factor.
control in electric power systems. It is one of the
well-known documents for power quality limits.
IEEE-519 is more comprehensive than IEC 61000-
3-2 [2], but it is not a product standard. The first
official version of this document was published in
1981. Product testing standards for the United States
are now considered within TC77A/WG1 (TF5b) but
are also discussed in IEEE. The current direction of
the TC-77 working group is toward a global IEC
standard for both 50/60 Hz and 115/230 V.
IEEE-519 contains thirteen sections, each with
standards and technical reports [11]:
9 Section 1 (Introduction and Scope). Includes
application of the standards.
9 Section 2 (Definition and Letter Symbols).
9 Section 3 (References). Includes standard
references.
9 Section 4 (Converter Theory and Harmonic Gen-
eration). Includes documents for converters, arc
furnaces, static VAr compensators, inverters for
dispersed generation, electronic control, trans-
formers, and generators.
9 Section 5 (System Response Characteristics).
Includes resonance conditions, effect of system
loading, and typical characteristics of industrial,
distribution, and transmission systems.
9 Section 6 (Effect of Harmonics). Detrimental
effects of harmonics on motors, generators,
transformers, capacitors, electronic equipments,
meters, relaying, communication systems, and
converters.
9 Section 7 (Reactive Power Compensation and
Harmonic Control). Discusses converter power
factor, reactive power compensation, and control
of harmonics.
9 Section 8 (Calculation Methods). Includes calcula-
tions of harmonic currents, telephone interfer-
ence, line notching, distortion factor, and power
factor.
9 Section 9 (Measurements). For line notching, har-
monic voltage and current, telephone interface,
flicker, power factor improvement, instrumenta-
tion, and statistical characteristics of harmonics.
9 Section 10 (Recommended Practices for Individ-
ual Consumers). Addresses standard impedance,
customer voltage distortion limits, customer appli-
cation of capacitors and filters, effect of multiple
sources at a single customer, and line notching
calculations.
9 Section 11 (Recommended Harmonic Limits on
the System). Recommends voltage distortion
limits on various voltage levels, TIF limits versus
voltage level, and IT products.
9 Section 12 (Recommended Methodology for Eval-
uation of New Harmonic Sources).
9 Section 13 (Bibliography). Includes books and
general discussions.
IEEE-519 sets limits on the voltage and current
harmonics distortion at the point of common cou-
pling (PCC, usually the secondary of the supply
transformer). The total harmonic distortion at the
PCC is dependent on the percentage of harmonic
distortion from each nonlinear device with respect
to the total capacity of the transformer and the rela-
tive load of the system. There are two criteria that
are used in IEEE-519 to evaluate harmonics
distortion:
9 limitation of the harmonic current that a user can
transmit/inject into utility system (THDi), and

40. 34 CHAPTER 1
TABLE 1.7 IEEE-519 Harmonic Current Limits [1, 64] for Nonlinear Loads at the Point of Common Coupling (PCC) with Other
Loads at Voltages of 2.4 to 69 kV
Maximum harmonic current distortion at PCC (% of fundamental)
Harmonic order (odd harmonics)"
I, cllL h < 11 11 _< h < 17 17 < h < 23 23 < h < 35 h > 35 THDi
<20 b 4.0 2.0 1.5 0.6 0.3 5.0
20-50 7.0 3.5 2.5 1.0 0.5 8.0
50-100 10.0 4.5 4.0 1.5 0.7 12.0
100-1000 12.0 5.5 5.0 2.0 1.0 15.0
>1000 15.0 7.0 6.0 2.5 1.4 20.0
aEven harmonics are limited to 25 % of the odd harmonic limits above.
bAll power generation equipment is limited to these values of current distortion, regardless of the actual I,c/IL.
Here I,c = maximum short circuit current at PCC,
IL = maximum load current (fundamental frequency) at PCC.
For PCCs from 69 to 138 kV, the limits are 50% of the limits above. A case-by-case evaluation is required for PCCs of 138 kV
and above.
TABLE 1.8 IEEE-519 Harmonic Voltage Limits [1, 64] for
Power Producers (Public Utilities or Cogenerators)
i
Harmonic voltage distortion (% at PCC)
2.3 to 69 kV 69 to 138 kV >138 kV
3.0 1.5 1.0 Maximum for
individual
harmonics
Total harmonic
distortion
(THDv)
5.0 2.5 1.5
Zs = Rs + jX s I
+ -i rZIconsumer,
l ~ L~176 user,
- ] t -4- j load
i I
FIGURE 1.23 Equivalent circuit of power system and non-
linear load. Zs is small (or Isc is large) for strong systems,
and Zs is large (or Isc is small) for weak systems.
9 limitation of the voltage distortion that the utility
must furnish the user (THDv).
The interrelationship of these two criteria shows that
the harmonic problem is a system problem and not
tied just to the individual load that generates the
harmonic current.
Tables 1.7 and 1.8 list the harmonic current and
voltage limits based on the size of the user with
respect to the size of the power system to which the
user is connected [1, 64].
The short-circuit current ratio (Rsc) is defined as
the ratio of the short-circuit current (available at the
point of common coupling) to the nominal funda-
mental load current (Fig. 1.23):
Rsc- [iscl (1-41)
-- iL "
Thus the size of the permissible nonlinear user load
increases with the size of the system; that is, the
stronger the system, the larger the percentage of
harmonic current the user is allowed to inject into
the utility system.
Table 1.8 lists the amount of voltage distortion [1,
64] specified by IEEE-519 that is acceptable for a
user as provided by a utility. To meet the power
quality values of Tables 1.7 and 1.8, cooperation
among all users and the utility is needed to ensure
that no one user deteriorates the power quality
beyond these limits. The values in Table 1.8 are low
enough to ensure that equipment will operate
correctly.
1.7 HARMONIC MODELING PHILOSOPHIES
For the simulation and modeling of power systems,
the dynamic operation is normally subdivided into
well-defined quasi steady-state regions [5]. Differen-
tial equations representing system dynamics in each
region are transformed into algebraic relations, and
the circuit is solved at the fundamental frequency (50
or 60 Hz) in terms of voltage and current phasors.
Modern power systems have many nonlinear com-
ponents and loads that produce voltage and current
harmonics. By definition, harmonics result from
periodic steady-state conditions, and therefore their
simulation should also be formulated in terms of
harmonic phasors. Considering the complicated

41. Introduction to Power Quality 35
nature of many nonlinear loads (sources) and their
couplings with the harmonic power flow, sophisti-
cated modeling techniques are required for accurate
simulation. Three techniques are usually used for
harmonic analysis of power systems in the presence
of nonlinear loads and/or components: time-domain
simulation, frequency (harmonic)-domain modeling,
and iterative procedures. The more recent approaches
may use time-domain, frequency-domain or some
combination of time- and frequency-domain tech-
niques to achieve a more accurate solution (e.g., the
main structure of many harmonic power flow algo-
rithms are based on a frequency-domain technique,
while nonlinear loads are modeled in a time-domain
simulation).
1.7.1 Time-Domain Simulation
Dynamic characteristics of power systems are
represented in terms of nonlinear sets of differential
equations that are normally solved by numerical
integration [5]. There are two commonly used time-
domain techniques:
9 state-variable approach, which is extensively used
for the simulation of electronic circuits (SPICE
[55]), and
9 nodal analysis, which is commonly used for elec-
tromagnetic transient simulation of power system
(EMTP [56]).
Two main limitations attached to the time-domain
methods for harmonic studies are
9 They usually require considerable computing time
(even for small systems) for the calculation of har-
monic information. This involves solving for the
steady-state condition and then applying a fast
Fourier transform (FFT); and
9 There are some difficulties in time-domain model-
ing of power system components with distributed
or frequency-dependent parameters.
The Electromagnetic Transient Program (EMTP)
and PSpice are two of the well-known time-domain
programs that are widely used for transient and har-
monic analyses. Most examples of this book are
solved using the PSpice software package.
1.7.2 Harmonic-Domain Simulation
The most commonly used model in the frequency
domain assumes a balanced three-phase system (at
fundamental and harmonic frequencies) and uses
single-phase analysis, a single harmonic source, and
a direct solution [5]. The injected harmonic currents
by nonlinear power sources are modeled as constant-
current sources to make a direct solution possible. In
the absence of any other nonlinear loads, the effect
of a given harmonic source is often assessed with the
help of equivalent harmonic impedances. The single-
source concept is still used for harmonic filter design.
Power systems are usually asymmetric. This justifies
the need for multiphase harmonic models and power
flow that considerably complicates the simulation
procedures.
For more realistic cases, if more than one har-
monic source is present in the power system, the
single-source concept can still be used, provided that
the interaction between them can be ignored. In
these cases, the principle of superposition is relied
on to compute the total harmonic distortion through-
out the network.
1.7.3 Iterative Simulation Techniques
In many modern networks, due to the increased
power ratings of nonlinear elements (e.g., HVDC
systems, FACTS devices, renewable energy sources,
and industrial and residential nonlinear loads) as
compared to the system short-circuit power, applica-
tion of superposition (as applied by harmonic-
domain techniques) is not justified and will provide
inaccurate results. In addition, due to the propaga-
tion of harmonic voltages and currents, the injected
harmonics of each nonlinear load is a function of
those of other sources. For such systems, accurate
results can be obtained by iteratively solving non-
linear equations describing system steady-state con-
ditions. At each iteration, the harmonic-domain
simulation techniques can be applied, with all non-
linear interactions included. Two important aspects
of the iterative harmonic-domain simulation tech-
niques are:
9 Derivation of system nonlinear equations [5]. The
system is partitioned into linear regions and non-
linear devices (described by isolated equations).
The system solution then consists predominantly
of the solution for given boundary conditions as
applied to each nonlinear device. Many techniques
have been proposed for device modeling including
time-domain simulation, steady-state analysis,
analytical time-domain expressions [references 11,
13 of [5]], waveform sampling and FFT [reference
14 of [5]], and harmonic phasor analytical expres-
sions [reference 15 of [5]].
9 Solution of nonlinear equations [5]. Early methods
used the fixed point iteration procedure of Gauss-
Seidel that frequently diverges. Some techniques

42. 36 CHAPTER 1
replace the nonlinear devices at each iteration by
a linear Norton equivalent (which might be
updated at the next iteration). More recent
methods make use of Newton-type solutions and
completely decouple device modeling and system
solution. They use a variety of numerical analysis
improvement techniques to accelerate the solution
procedure.
Detailed analyses of iterative simulation tech-
niques for harmonic power (load) flow are presented
in Chapter 7.
1.7.4 Modeling Harmonic Sources
As mentioned above, an iterative harmonic
power flow algorithm is used for the simulation of
the power system with nonlinear elements. At each
iteration, harmonic sources need to be accurately
included and their model must be updated at the
next iteration.
For most harmonic power flow studies it is suitable
to treat harmonic sources as (variable) harmonic
currents. At each iteration of the power flow algo-
rithm, the magnitudes and phase angles of these har-
monic currents need to be updated. This is performed
based on the harmonic couplings of the nonlinear
load. Different techniques have been proposed to
compute and update the values of injected harmonic
currents, including:
9 Thevenin or Norton harmonic equivalent
circuits,
9 simple decoupled harmonic models for the estima-
tion of nonlinear loads (e.g., Ih = 1/h, where h is the
harmonic order),
9 approximate modeling of nonlinear loads (e.g.,
using decoupled constant voltage or current har-
monic sources) based on measured voltage and
current characteristics or published data, and
9 iterative nonlinear (time- and/or frequency-based)
models for detailed and accurate simulation of
harmonic-producing loads.
1.8 POWER QUALITY IMPROVEMENT
TECHNIQUES
Nonlinear loads produce harmonic currents that can
propagate to other locations in the power system and
eventually return back to the source. Therefore, har-
monic current propagation produces harmonic volt-
ages throughout the power systems. Many mitigation
techniques have been proposed and implemented to
maintain the harmonic voltages and currents within
recommended levels:
9 high power quality equipment design,
9 harmonic cancellation,
9 dedicated line or transformer,
9 optimal placement and sizing of capacitor banks,
9 derating of power system devices, and
9 harmonic filters (passive, active, hybrid) and
custom power devices such as active power line
conditioners (APLCs) and unified or universal
power quality conditioners (UPQCs).
The practice is that if at PCC harmonic currents
are not within the permissible limits, the consumer
with the nonlinear load must take some measures to
comply with standards. However, if harmonic volt-
ages are above recommended levels- and the har-
monic currents injected comply with standards - the
utility will have to take appropriate actions to
improve the power quality.
Detailed analyses of improvement techniques for
power quality are presented in Chapters 8 to 10.
1.8.1 High Power Quality Equipment Design
The use of nonlinear and electronic-based devices is
steadily increasing and it is estimated that they will
constitute more than 70% of power system loading
by year 2010 [10]. Therefore, demand is increasing
for the designers and product manufacturers to
produce devices that generate lower current distor-
tion, and for end users to select and purchase high
power quality devices. These actions have already
been started in many countries, as reflected by
improvements in fluorescent lamp ballasts, inclusion
of filters with energy saving lamps, improved PWM
adjustable-speed drive controls, high power quality
battery chargers, switch-mode power supplies, and
uninterruptible power sources.
1.8.2 Harmonic Cancellation
There are some relatively simple techniques that use
transformer connections to employ phase-shifting for
the purpose of harmonic cancellation, including [10]:
9 delta-delta and delta-wye transformers (or multi-
ple phase-shifting transformers) for supplying har-
monic producing loads in parallel (resulting in
twelve-pulse rectifiers) to eliminate the 5th and
7th harmonic components,
9 transformers with delta connections to trap and
prevent triplen (zero-sequence) harmonics from
entering power systems,
9 transformers with zigzag connections for cancella-
tion of certain harmonics and to compensate load
imbalances,

43. Introduction to Power Quality 37
9 other phase-shifting techniques to cancel higher
harmonic orders, if required, and
9 canceling effects due to diversity [57-59] have
been discovered.
1.8.3 Dedicated Line or Transformer
Dedicated (isolated) lines or transformers are used
to attenuate both low- and high-frequency electrical
noise and transients as they attempt to pass from one
bus to another. Therefore, disturbances are pre-
vented from reaching sensitive loads and any load-
generated noise and transients are kept from reaching
the remainder of the power system. However, some
common-mode and differential noise can still reach
the load. Dedicated transformers with (single or
multiple) electrostatic shields are effective in elimi-
nating common-mode noise.
Interharmonics (e.g., caused by induction motor
drives) and voltage notching (e.g., due to power elec-
tronic switching) are two examples of problems that
can be reduced at the terminals of a sensitive load
by a dedicated transformer. They can also attenuate
capacitor switching and lightning transients coming
from the utility system and prevent nuisance tripping
of adjustable-speed drives and other equipment. Iso-
lated transformers do not totally eliminate voltage
sags or swells. However, due to the inherent large
impedance, their presence between PCC and the
source of disturbance (e.g., system fault) will lead to
relatively shallow sags.
An additional advantage of dedicated transform-
ers is that they allow the user to define a new ground
reference that will limit neutral-to-ground voltages
at sensitive equipment.
1.8.3.1 Application Example 1.6: Interhar-
monic Reduction by Dedicated Transformer
Figure E1.6.1 shows a typical distribution system
with linear and nonlinear loads. The nonlinear load
(labeled as "distorting nonlinear load") consists of
two squirrel-cage induction motors used as prime
movers for chiller-compressors for a building's air-
conditioning system. This load produces interhar-
monic currents that generate interharmonic voltage
drops across the system's impedances resulting in
the interharmonic content of the line-to-line voltage
of the induction motors as given by Table El.6.1.
Some of the loads are very sensitive to interharmon-
ics and these must be reduced at the terminals of
sensitive loads. These loads are labeled as "sensitive
loads."
Three case studies are considered:
9 Case #1: Distorting nonlinear load and sensitive
loads are fed from the same pole transformer (Fig.
E1.6.2).
dedicated
line or transformer
LLLj115
kV
Substation / distribution
~77
three-phase transformer
.62 kV
62ekV
T1 transformer
20 V
I 7.62 kV
9 * 9149 pole
~~,~ transformer
120 V
+ T11128 = 1 A
] _
v1128-?
I I I I I I I
sensitive loads distorting linear other
(e.g., computing equipments) nonlinear load load linear loads
FIGURE E1.6.1 Overall (per phase) one-line diagram of the distribution system used in Application Example 1.6.

44. 38 CHAPTER 1
Case # 1
Substation / distribution
three-phase transformer
V1128= ?
I
sensitive loads
(e.g., computing equipments)
vJ.
115 kV
~7.;2 ekV
~.~ transformer
120 V
Ak,
II128=1A
I I
distorting
nonlinear load
FIGURE E1.6.2 Case #1 of Application Example 1.6: distorting nonlinear load and sensitive loads are fed from same pole
transformer.
TAB L E E 1.6.1 Interharmonics of Phase Current and Line-to-
Line Voltage Generated by a Three-Phase Induction Motor
[34]
Interharmonic Interharmonic
Interharmonic fh amplitude of amplitude of line-
(Hz) phase current (%) to-line voltage (%)
1128 7 0.40
1607 10 0.40
1730 10 0.55
9 Case #2: A dedicated 1:1 isolation transformer is
used between the distorting nonlinear load and
sensitive loads (Fig. E1.6.3).
9 Case #3: A dedicated 7.62 kV to 120 V pole trans-
former is used between the distorting nonlinear
load and sensitive loads (Fig. E1.6.4).
1.8.4 Optimal Placement and Sizing of
Capacitor Banks
It is well known that proper placement and sizing of
shunt capacitor banks in distorted networks can
result in reactive power compensation, improved
voltage regulation, power factor correction, and
power/energy loss reduction. The capacitor place-
ment problem consists of determining the optimal
numbers, types, locations, and sizes of capacitor
banks such that minimum yearly cost due to peak
power/energy losses and cost of capacitors is
achieved, while the operational constraints are main-
tained within required limits.
Most of the reported techniques for capacitor
placement assume sinusoidal operating conditions.
These methods include nonlinear programming, and
near global methods (genetic algorithms, simulated
annealing, tabu search, artificial neural networks,
and fuzzy theory). All these approaches ignore
the presence of voltage and current harmonics
[60, 61].
Optimal capacitor bank placement is a well-
researched subject. However, limited attention is
given to this problem in the presence of voltage and
current harmonics. Some publications have taken
into account the presence of distorted voltages for
solving the capacitor placement problem. These
investigations include exhaustive search, local varia-
tions, mixed integer and nonlinear programming,
heuristic methods for simultaneous capacitor and
filter placement, maximum sensitivities selection,
fuzzy theory, and genetic algorithms.
According to newly developed investigations
based on fuzzy and genetic algorithms [60, 61],
proper placement and sizing of capacitor banks in
power systems with nonlinear loads can result in
lower system losses, greater yearly benefits, better
voltage profiles, and prevention of harmonic parallel
resonances, as well as improved power quality.
Simulation results for the standard 18-bus IEEE

45. Introduction to Power Quality 39
Case #2
Substation / distribution
three-phase transformer
120 V
1:1 isolation
transformer
20 V +
1128 =?
I
sensitive loads
(e.g., computing equipments)
.Aa115
kV
~7.:o21ekV
~, ~ transformer
120 V
I 1128=1 A
\/
7-
m
I I
distorting
nonlinear load
FIGURE E1.6.3 Case #2 of Application Example 1.6: use of an isolation transformer with a turns ratio 1 9 1 between dis-
torting (nonlinear) load and sensitive loads.
/
Case #3 / 115 kV
Substation / distribution
three-phase transformer
7.62 kV
dedicated isolation
pole transformer
20 V
+
V l 8-? _/
1
I I I I
sensitive loads distorting
(e.g., computing equipments) nonlinear load
.62 kV
pole
~i transformer
120 V
1128 = 1A
FIGURE E1.6.4 Case #3 of Application Example 1.6: use of a dedicated (isolation transformer with turns ratio 7620" 120)
pole transformer between distorting nonlinear load and sensitive loads.
distorted distribution system show that proper
placement and sizing of capacitor banks can limit
voltage and current harmonics and decrease their
THDs to the recommended levels of IEEE-519,
without application of any dedicated high-order
passive or active filters. For cases where the con-
struction of new capacitor bank locations is not
feasible, it is possible to perform the optimization
process without defining any new locations. There-
fore, reexamining capacitor bank sizes and locations

46. 40 CHAPTER 1
before taking any major steps for power quality miti-
gation is highly recommended.
Detailed analyses for optimal sizing and place-
ment of capacitor banks in the presence of harmon-
ics and nonlinear loads are presented in Chapter
10.
1.8.5 Derating of Power System Devices
Power system components must be derated when
supplying harmonic loads. Commercial buildings
have drawn the most attention in recent years due to
the increasing use of nonlinear loads. According to
the IEEE dictionary, derating is defined as "the
intentional reduction of stress/strength ratio (e.g.,
real or apparent power) in the application of an
item (e.g., cables, transformer, electrical machines),
usually for the purpose of reducing the occurrence
of stress-related failure (e.g., reduction of lifetime
due to increased temperature beyond rated tempera-
ture)." As discussed in Section 1.5, harmonic cur-
rents and voltages result in harmonic losses of
magnetic devices, increasing their temperature rise
[62]. This rise beyond the rated value results in a
reduction of lifetime, as will be discussed in Chapter
6.
There are several techniques for determining the
derating factors (functions) of appliances for non-
sinusoidal operating conditions (as discussed in
Chapter 2), including:
9 from tables in standards and published research
(e.g., ANSI/IEEE Std C57.110 [63] for transformer
derating),
9 from measured (or computed) losses,
9 by determining the K-factor, and
9 based on the Fnu-factor.
1.8.6 Harmonic Filters, APLCs, and UPQCs
One means of ensuring that harmonic currents of
nonlinear components will not unduly interact with
the remaining part of the power system is to place
filters near or close to nonlinear loads. The main
function of a filter is either to bypass harmonic cur-
rents, block them from entering the power system,
or compensate them by locally supplying harmonic
currents. Due to the lower impedance of the filter in
comparison to the impedance of the system, har-
monic currents will circulate between the load and
the filter and do not affect the entire system; this is
called series resonance. If other frequencies are to
be controlled (e.g., that of arc furnaces), additional
tuned filters are required.
Harmonic filters are broadly classified into passive,
active, and hybrid structures. These filters can only
compensate for harmonic currents and/or harmonic
voltages at the installed bus and do not consider the
power quality of other buses. New generations of
active filters are active-power line conditioners that
are capable of minimizing the power quality of the
entire system.
Passive filters are made of passive components
(inductance, capacitance, and resistance) tuned to
the harmonic frequencies that are to be attenuated.
The values of inductors and capacitors are selected
to provide low impedance paths at the selected
frequencies. Passive filters are generally designed
to remove one or two harmonics (e.g., the 5th and
7th). They are relatively inexpensive compared with
other means for eliminating harmonic distortion,
but also suffer from some inherent limitations,
including:
9 Interactions with the power system;
9 Forming parallel resonance circuits with system
impedance (at fundamental and/or harmonic fre-
quencies). This may result in a situation that is
worse than the condition being corrected. It may
also result in system or equipment failure;
9 Changing characteristics (e.g., their notch fre-
quency) due to filter parameter variations;
9 Unsatisfactory performance under variations of
nonlinear load parameters;
9 Compensating a limited number of harmonics;
9 Not considering the power quality of the entire
system; and
9 Creating parallel resonance. This resonance fre-
quency must not necessarily coincide with any
significant system harmonic. Passive filters are
commonly tuned slightly lower than the attenu-
ated harmonic to provide a margin of safety in case
there are some changes in system parameters (due
to temperature variations and/or failures). For
this reason filters are added to the system starting
with the lowest undesired harmonic. For example,
installing a seventh-harmonic filter usually requires
that a fifth-harmonic filter also be installed.
Designing passive filters is a relatively simple but
tedious matter. For the proper tuning of passive
filters, the following steps should be followed:
9 Model the power system (including nonlinear
loads) to indicate the location of harmonic sources
and the orders of the injected harmonics. A har-
monic power (load) flow algorithm (Chapter 7)
should be used; however, for most applications

47. Introduction to Power Quality 41
with a single dominating harmonic source, a sim-
plified equivalent model and hand calculations are
adequate;
9 Place the hypothetical harmonic filter(s) in the
model and reexamine the system. Filter(s) should
be properly tuned to dominant harmonic frequen-
cies; and
9 If unacceptable results (e.g., parallel resonance
within system) are obtained, change filter
location(s) and modify parameter values until
results are satisfactory.
In addition to power quality improvement, har-
monic filters can be configured to provide power
factor correction. For such cases, the filter is designed
to carry resonance harmonic currents, as well as fun-
damental current.
Active filters rely on active power conditioning to
compensate for undesirable harmonic currents. They
actually replace the portion of the sine wave that is
missing in the nonlinear load current by detecting
the distorted current and using power electronic
switching devices to inject harmonic currents with
complimentary magnitudes, frequencies, and phase
shifts into the power system. Their main advantage
over passive filters is their fine response to changing
loads and harmonic variations. Active filters can be
used in very difficult circumstances where passive
filters cannot operate successfully because of parallel
resonance within the system. They can also take care
of more than one harmonic at a time and improve or
mitigate other power quality problems such as flicker.
They are particularly useful for large, distorting non-
linear loads fed from relatively weak points of the
power system where the system impedance is rela-
tively large. Active filters are relatively expensive
and not feasible for small facilities.
Power quality improvement using filters, optimal
placement and sizing of shunt capacitors, and unified
power quality conditioners (UPQCs) are discussed
in Chapters 9, 10, and 11, respectively.
1.8.6.1 Application Example 1.7: Hand
Calculation of Harmonics Produced by Twelve.
Pulse Converters
Figure E1.7.1 shows a large industrial plant such as
an oil refinery or chemical plant [64] being serviced
from a utility with transmission line-to-line voltage
of 115 kV. The demand on the utility system is 50
MVA and 50% of its load is a twelve-pulse static
power converter load.
Table E1.7.1 lists the harmonic currents (Ih) given
in pu of the fundamental current based on the com-
TABLE E1.7.1 Harmonic Current (Ih) Generated by Six-
Pulse and Twelve-Pulse Converters [64] Based on X~ = 0.12 pu
and a = 30 ~
Harmonic Ih for 6-pulse Ih for 12-pulse
order (h) converter (pu) converter (pu)
1 1.000 1.000
5 0.192 0.0192
7 0.132 0.0132
11 0.073 0.073
13 0.057 0.057
17 0.035 0.0035
19 0.027 0.0027
23 0.020 0.020
25 0.016 0.016
29 0.014 0.0014
31 0.012 0.0012
35 0.011 0.011
37 0.010 0.010
41 0.009 0.0009
43 0.008 0.0008
47 0.008 0.008
49 0.007 0.007
mutating reactance X~ = 0.12 pu and the firing angle
a = 30 ~ of six-pulse and twelve-pulse converters. In
an ideal twelve-pulse converter, the magnitude of
some current harmonics (bold in Table E1.7.1) is
zero. However, for actual twelve-pulse converters,
the magnitudes of these harmonics are normally
taken as 10% of the six-pulse values [64].
1.8.6.2 Application Example 1.8:
Filter Design to Meet IEEE.519 Requirements
Filter design for Application Example 1.7 will be
performed to meet the IEEE-519 requirements. The
circuit of Fig. E1.7.1 is now augmented with a passive
filter, as shown by Fig. E1.8.1.
1.8.6.3 Application Example 1.9:
Several Users on a Single
Distribution Feeder
Figure El.9.1 shows a utility distribution feeder that
has four users along a radial feeder [64]. Each user
sees a different value of short-circuit impedance or
system size. Note that
10MVA
Ssc = MVAsc =
Zsys[PU at 10MVA base]
There is one type of transformer (A-Y);
therefore, only six-pulse static power converters are
used.

48. 42 CHAPTER 1
00 pu T
PCC #1
Z sy*=O.O23pu
m
Linear
loads
25 MVA
-t, = 13.8 kV 1,cc #2
~/~ nonlinear loads ~/~
12.5MVAat I-- --I 12.5MVAat
cosO =10 I I cos~= 1.0
Mw [ j 12.5 Mw
*) base: Sbase=lO MVA
FIGURE E1.7.1 One-line diagram of a large industrial plant fed from transmission voltage [64].
* =0.5%
Z sys 115kV
PCC #1
Z * -2.3%
sys 13.8kV-"
linear load
25 MVA
t ZllskV0.5%
115 kVL_ L
t Z13.8 kV-- 2.3*-0.5%*=1.8%
13.8 kVL_ L
I-- --I
I ~_ 7 I n~176 filter
I --~ - I (12 pulse converter) Z f
L --' 1.25 (2) MW=25 MW
*) base: Sbase 10MVA
FIGURE El.8.1 One-line diagram of a large industrial plant fed from transmission voltage (Fig. El.7.1) with a passive
filter placed at PCC #2.
1.9 SUMMARY
The focus of this chapter has been on definition,
measures, and classification of electric power quality
as well as related issues that will be covered in the
following chapters. Power quality can be defined as
"the measure, analysis, and improvement of the bus
voltage to maintain a sinusoidal waveform at rated
voltage and frequency." Main causes of disturbances
and power quality problems are unpredictable
events, the electric utility, the customer, and the
manufacturer.
The magnitude-duration plot can be used to clas-
sify power quality events, where the voltage magni-
tude is split into three regions (e.g., interruption,
undervoltage, and overvoltage) and the duration of
these events is split into four regions (e.g., very short,
short, long, and very long). However, IEEE stan-
dards use several additional terms to classify power
quality events into seven categories including: tran-
sient, short-duration voltage variation, long-duration
voltage variation, voltage imbalance, waveform dis-
tortion, voltage fluctuation (and flicker), and power-
frequency variation. Main sources for the formulations
and measures of power quality are IEEE Std 100,
IEC Std 61000-1-1, and CENELEC Std EN 50160.
Some of the main detrimental effects of poor power

49. Introduction to Power Quality 43
S sc PCC #1 "-
10MVA
(0.02857)
= 350 MVA
Sbase = 10 MVA
13.8kVc. L
0.02857pu
PCC #1
User # 1
0.22pu
I
2.5 MVA
9 7.958 kV
L-N
0.480 kVL_ L V h PCC user #1
I I '--'
1.87 MVA [ [ 0.625 MW
_ _ ]
~, 0.833 MVA per phase
S sc PCC #2 --
10MVA
(0.02857+0.00476)
= 300 MVA
PCC #2
0.00476pu
User #2
0.11pu
Y
4.16 kV L-L Vh PCC user #2
i i- -I
2.5 MVA [ [ 2.5 MW
~: k 2
_ _ [
5 MVA 9 1.667 MVA per phase
= 10MVA 0.0238pu
Ssc Pcc #3 (0.02857+0.00476+0.0238)
= 175 MVA /~ 3113 Y 4 16 kVL_ L
Pec#3 3113 ~i
User #3 I [ -" "-'1
00 pu ! !'MW
I ~ - I
10MVA 0.02286pu 10 MVA 9 3.33 MVA per phase
Ssr PCC#4= (0.02857+0.00476+0.0238+0.02286) 9
= 2 MW lillY 4.16 kVL_ L
pcc #4 T
I- -I
User #4
0.11pu 1.25MVA I I 3.75 MW
5 MVA 9 1.667 MVA per phase
FIGURE El,9,1 Overall one-line diagram of the distribution system feeder containing four users with six-pulse converters
[64].

50. 44 CHAPTER 1
Rsyst Xsyst
B- ~/
+ VAB(t) iAL(t) l~
A ~
Rsyst Xsyst 9
VBC(t)
VCA(t)
iAph (t) I
_ + Rsyst Xsyst
C-
I
iaph(t)
r
a ~ + D~
ab(t) g
I I I I
tD3:
2
i o Cf R,oad
9 v
power system A/Y transformer rectifier
II I I I
filter load
FIGURE P1.1 Connection of a delta/wye three-phase transformer with a diode rectifier, filter, and load.
Vioad ( t )
quality include increase or decrease of the funda-
mental voltage component, additional losses, heating,
and noise, decrease of appliance and equipment life-
time, malfunction and failure of components, con-
trollers, and loads, resonance and ferroresonance,
flicker, harmonic instability, and undesired (har-
monic, subharmonic, and interharmonic) torques.
Documents for control of power quality come in
three levels of applicability and validity: guidelines,
recommendations, and standards. IEEE-Std 519 and
IEC 61000 (or EN 61000) are the most commonly
used references for power quality in the United
States and Europe, respectively.
Three techniques are used for harmonic analysis:
time-domain simulation, frequency (harmonic)-
domain modeling, and iterative procedures.
Many mitigation techniques for controlling power
quality have been proposed, including high power
quality equipment design, harmonic cancellation,
dedicated line or transformer, optimal placement
and sizing of capacitor banks, derating of devices,
harmonic filters (passive, active, hybrid), and custom-
build power devices. The practice is that if at PCC
harmonic currents are not within the permissible
limits, the consumer with the nonlinear load must
take some measures to comply with standards.
However, if harmonic voltages are above recom-
mended levels-and the harmonic currents injected
comply with standards- the utility will have to take
appropriate actions to improve the power quality.
Nine application examples with solutions are pro-
vided for further clarifications of the presented
materials. The reader is encouraged to read the over-
view of the text given in the preface before delving
further into the book.
1.10 PROBLEMS
Problem 1.1" Delta/wye Three-Phase
Transformer Configuration
a) Perform a PSpice analysis for the circuit of Fig.
PI.1, where a three-phase diode rectifier with
filter (e.g., capacitor G) serves a load (Rload). You
may assume ideal transformer conditions. For
your convenience you may assume (N1/N2)= 1,
Rsyst = 0.01 ~-~, Xsyst = 0.05 ~'2 @ f= 60 Hz, VAB(t ) =
~/2600V cosa)t, VBc(t ) = 4~600V cos(a)t- 120~
VCA (t) = ~/2600V cos(09t- 240~ ideal diodes D1
to D6, Cf= 500//F, and Rloaa = 10~. Plot one
period of either voltage or current after steady
state has been reached as requested in parts b
to e.
b) Plot and subject the line-to-line voltages VAB(t )
and Vab(t) to Fourier analysis. Why are they
different?
c) Plot and subject the input line current iaL(t)
of the delta primary to a Fourier analysis.
Note that the input line currents of the primary
delta do not contain the 3rd, 6th, 9th, 12th,...,
that is, harmonic zero-sequence current
components.
d) Plot and subject the phase current iAph(t) of the
delta primary to a Fourier analysis. Why do the
phase currents of the primary delta not contain
the 3rd, 6th, 9th, 12th,..., that is, harmonic zero-
sequence current components?
e) Plot and subject the output current iaph(t) of the
wye secondary to a Fourier analysis. Why do the
output currents of the secondary wye not contain
the 3rd, 6th, 9th, 12th ..... that is, zero-sequence
current components?

51. Introduction to Power Quality 45
Problem 1.2: Voltage Phasor Diagrams
of a Three-Phase Transformer in Delta/
Zigzag Connection
Figure P1.2 depicts the so-called delta/zigzag config-
uration of a three-phase transformer, which is used
for supplying power to unbalanced loads and three-
phase rectifiers. You may assume ideal transformer
conditions. Draw a phasor diagram of the primary
and secondary voltages when there is no load on
the secondary side. For your convenience you may
assume (Na/N2) = 1. For balanced phase angles 0 ~
120 ~ , and 240 ~ of voltages and currents you may use
hexagonal paper.
Problem 1.3" Current Phasor Diagrams of a
Three-Phase Transformer in Delta/Zigzag
Connection With Line-To-Line Load
The delta/zigzag, three-phase configuration is used
for feeding unbalanced loads and three-phase recti-
fiers. You may assume ideal transformer conditions.
Even when only one line-to-line load (e.g., Rloaa) of
the secondary is present as indicated in Fig. P1.3, the
primary line currents ILA, ILB, and I~c will be bal-
anced because the line-to-line load is distributed to
all three (single-phase) transformers. This is the
advantage of a delta/zigzag configuration. If there is
a resistive line-to-line load on the secondary side
primary
C-
A: _ A~'~C-~VC~H~ I
Be 2 . m2
B
X 3
I
4
A
X 4
N2 i ~XA3X4
A
x 3
X!t ~FVxIx 2 N "A
X A(:+eutral
c
B N2_ ~fe e-"~i N 2 X C
secondary
~2 C
eC
+
+
Vbc
:b Vca
+
V.b
ea
FIGURE P1.2 Connection of a delta/zigzag, three-phase transformer with the definition of primary and secondary
voltages.
A
C-_ ILC primary x4
N2
A
iLA C ~ X3 A
A= I
iA X~ :eutrai
X B , X C
B ILBH2 B N2~klQ~~X~X~N2xC
: . x~~_ ~
x3 I '~,
_B N21-f~']
secondary
r
: C
:b
Rl~ [ "'
~oad +Vl~
. - = a
FIGURE P1.3 Connection of a delta/zigzag, three-phase transformer with the definition of current for line-to-line load.

52. 46 CHAPTER 1
C ]'LC primary
A: iLA,~ - C ~ i
B: ILBH2
H
1 B
X 3
B N~~ x4f<
Itoad
At.
X4 secondary
N 2
A
X3 *C
/
::lJ -od
xB N~Y~ ~N2x( eL~! N~2 c ~ b
'~oad a
Vload
FIGURE P1.4 Connection of a delta/zigzag, three-phase transformer with the definition of current for line-to-neutral
load.
(lI~oadl- 10 A) present as illustrated in Fig. P1.3, draw
a phasor diagram of the primary and secondary cur-
rents as defined in Fig. P1.3. For your convenience
you may assume that the same voltage definitions
apply as in Fig. P1.2 and (N1/N2) = 1. For balanced
phase angles 0 ~ 120 ~ and 240 ~ of voltages and cur-
rents you may use hexagonal paper.
Problem 1.4: Current Phasor Diagrams of a
Three-Phase Transformer in Delta/Zigzag
Connection with Line-To-Neutral Load
Repeat the analysis of Problem 1.3 if there is a resis-
tive line-to-neutral load on the secondary side
(lI~oadl = 10 A) present, as illustrated in Fig. P1.4; that
is, draw a phasor diagram of the primary and second-
ary currents as defined in Fig. P1.4. For your con-
venience you may assume that the same voltage
definitions apply as in Fig. P1.2 and (N1/N2)= 1. In
this case the load is distributed to two (single-phase)
transformers. For balanced phase angles 0 ~ 120 ~ and
240 ~ of voltages and currents you may use hexagonal
paper.
Problem 1.5: Current Phasor Diagrams of a
Three-Phase Transformer in Delta/Zigzag
Connection with Three-Phase Unbalanced Load
Repeat the analysis of Problem 1.3 if there is a
resistive unbalanced load on the secondary side
(llloadal- 30 A, II~oadbl- 20 A, II~oadc[ = 10 A) present as
illustrated in Fig. P1.5; that is, draw a phasor diagram
of the primary and secondary currents as defined in
Fig. P1.5. For your convenience you may assume that
the same voltage definitions apply as in Fig. P1.2 and
(N1/N2) = 1. For balanced phase angles 0 ~ 120 ~ and
240 ~ of voltages and currents you may use hexagonal
paper.
Problem 1.6: Delta/Zigzag Three-Phase
Transformer Configuration without Filter
Perform a PSpice analysis for the circuit of Fig. P1.6
where a three-phase diode rectifier without filter
(e.g., capacitance Cy=0) serves Rload. YOU may
assume ideal transformer conditions. For your con-
venience you may assume (N1/N2) = 1, Rsyst- 0.01 ~2,
Ssyst = 0.05 ~ @ f-- 60 Hz, 1;AB(t ) = ,J~600V cos(or,
VBc(t ) = ,~600V cos(o)t- 120~ VCA (t) = 4~600V
cos((ot - 240 ~ ,ideal diodes D1 to D6, and R~oad = 10 f2.
Plot one period of either voltage or current after
steady state has been reached as requested in the
following parts.
a) Plot and subject the line-to-line voltages VAB(t)
and Yah(t) to a Fourier analysis. Why are they
different?
b) Plot and subject the input line current imL(t) of the
delta primary to a Fourier analysis. Note that the
input line currents of the primary delta do not
contain the 3rd, 6th, 9th, 12th .... , that is, har-
monic zero-sequence current components.
c) Plot and subject the phase current iaph(t) of the
delta primary to a Fourier analysis. Why do the
phase currents of the primary delta not contain
the 3rd, 6th, 9th, 12th ..... that is, harmonic zero-
sequence current components?
d) Plot and subject the output current iaph(t) of the
zigzag secondary to a Fourier analysis. Why do

53. Introduction to Power Quality 47
C_- I~c~
A:
B:
primary
y
i~A C i
i~ N,
~ H A
,~B 21 ~.z'_
H 1 B /" I n
B
X 3
,, Njq
I i X4(~2 t
power I
system
At1
X 4
N2 ~2 secondary
A
X 3
~
xA~
~" ]neutral
N XIB~XCN c
x B ~'~, *'~x 2
Ic2 I
delta / zigzag transformer
,o.d7
v
~oad b
b
toad a
a
I
asymmetric load
FIGURE P1.5 Connection of a delta/zigzag, three-phase transformer with the definition of currents for three-phase unbal-
anced line-to-neutral loads.
+ VAB(t) iAL(t) ..
+
A:
Rsyst Xsyst H 1
Vec(t) ]
vcA(t) iAph(t) ~
- + HA
Rsyst Xsyst
xAt I
H C
I +
xAt. 2 / Vab't' ad(t'
4 N, .> ..,t,X 1 c I
__ / B N~d~"W. x21 ~r.~_~_ .~.. ] ~'Rlo
f NlJ H2 X B (~rR Xl N2~ ~ C ad
I A -~ ~ N~-~! x~ -
H1 _
I I I-" I II li I
power system delta I zigzag transformer rectifier Fdter load
FIGURE P1.6 Connection of a delta/zigzag, three-phase transformer with a diode rectifier and load Rload.
the output currents of the secondary zigzag not
contain the 3rd, 6th, 9th, 12th,..., that is, har-
monic zero-sequence current components?
e) Plot and subject the output voltage Vload(t) to a
Fourier analysis.
Problem 1.7: Delta/Zigzag Three-Phase
Transformer Configuration with Filter
Perform a PSpice analysis for the circuit of Fig. P1.6
where a three-phase diode rectifier with filter (e.g.,
capacitance C:= 500/IF) serves the load Rloaa. You
may assume ideal transformer conditions. For
your convenience you may assume (N1/N2)= 1,
Rsyst = 0.01 f2, Ssyst -- 0.05 ~ @ f= 60 Hz, VAB(t ) =
~,/2600V cos ogt, Vsc(t ) = ,f2600V cos(ogt - 120~
VCA (t) = ,~600V cos(~ot - 240~ ideal diodes D1 to
06, and Rload = 10 ~. Plot one period of either voltage
or current after steady state has been reached as
requested in the following parts.
a) Plot and subject the line-to-line voltages VAB(t)
and Vab(t) to a Fourier analysis. Why are they
different?
b) Plot and subject the input line current iaL(t) of the
delta primary to a Fourier analysis. Note that the
input line currents of the primary delta do not
contain the 3rd, 6th, 9th, 12th ..... that is, har-
monic zero-sequence current components.

54. 48 CHAPTER 1
c) Plot and subject the phase current iAph(t) of the
delta primary to a Fourier analysis. Why do the
phase currents of the primary delta not contain
the 3rd, 6th, 9th, 12th,..., that is, zero-sequence
current components?
d) Plot and subject the output current iaph(t) of the
zigzag secondary to a Fourier analysis. Why do
the output currents of the secondary zigzag not
contain the 3rd, 6th, 9th, 12th,..., that is, har-
monic zero-sequence current components?
e) Plot and subject the output voltage Vload(t) to a
Fourier analysis.
Problem 1.8: Transient Performance of a
Brushless Dc Motor Fed by a Fuel Cell
Replace the battery (with the voltage VDC = 300 V)
of Fig. El.3.1 by the equivalent circuit of the fuel cell
as described in Fig. 2 of [67]. You may assume that
in Fig. 2 of [67] the voltage E = 300 + 30 V, where the
superimposed rectangular voltage +30 V has a period
of T+_30 v = 1 s. The remaining parameters of the fuel
cell equivalent circuit can be extrapolated from
Table III of [67]. Repeat the analysis as requested in
Application Example 1.3.
Problem 1.9: Transient Performance of an
Inverter Feeding into Three-Phase Power
System When Supplied by a Fuel Cell
Replace the DC source (with the voltage V o = 390 V)
of Fig. El.5.1 by the equivalent circuit of the fuel cell
as described in Fig. 2 of [67]. You may assume that
in Fig. 2 of [67] the voltage E = 390 + 30 V, where the
superimposed rectangular voltage +30 V has a period
of T+_30v = 1 s. The remaining parameters of the fuel
cell equivalent circuit can be extrapolated from
Table III of [67]. Repeat the analysis as requested in
Application Example 1.5.
Problem 1.10" Suppression of Subharmonic of
30 Hz with a Dedicated Transformer
The air-conditioning drive (compressor motor) gen-
erates a subharmonic current of I30nz = 1 A due to
spatial harmonics (e.g., selection of number of slots,
rotor eccentricity). A sensitive load fed from the same
pole transformer is exposed to a terminal voltage with
the low beat frequency of 30 Hz. A dedicated trans-
former can be used to suppress the 30 Hz component
from the power supply of the sensitive load (see Fig.
E1.6.1 and Figs. E1.6.4 to E1.6.6).
The parameters of the single-phase pole trans-
former at 60Hz are Xse=S'pp=O.07~'2, Rsp =
R'pp = O.
a) Draw an equivalent circuit of the substation
transformer (per phase) and that of the pole
transformer.
b) Find the required leakage primary and secondary
leakage inductances Lpo and L,o of the substation
distribution transformer (per phase) for
Rpo = Rso = 0 such that the subharmonic voltage
across the sensitive load V30n, < 1 mV provided
Lso = L'po, where the prime refers the inductance
L of the primary to the secondary side of the dis-
tribution transformer.
c) Without using a dedicated transformer, design a
passive filter such that the same reduction of the
subharmonic is achieved.
Problem 1.11: Harmonic Currents
of a Feeder
For Application Example 1.9 (Fig. E1.9.1), calculate
the harmonic currents associated with users #3 and
#4. Are they within the permissible power quality
limits of IEEE-519?
Problem 1.12" Design a Filter So That the
Displacement (Fundamental Power) Factor
thtotal
COS "~"1 with filter will be 0.9 lagging (consumer notation)
r,4otal
COS tl, t 1 with filter ~- 1.0.
Figure Pl.12.1 shows the one-line diagram of an
industrial plant being serviced from a utility
transmission voltage at 13.8 kVL-L. The total
power demand on the utility system is 5 MVA:
3 MVA is a six-pulse static power converter load
(three-phase rectifier with firing angle a = 30 ~ note
COS (I)~ ~ -----0.955 cos a lagging), while the remain-
ing 2 MVA is a linear (induction motor) load at
COS (I)linear-" 0.8 lagging (inductive) displacement
(fundamental power) factor. The system impedance
is Zsyst : 10% referred to a 10 MVA base.
a) Calculate the short-circuit apparent power Ssc at
PCC.
b) Find the short-circuit current Iscphase.
C) Before filter installation, calculate the displace-
/~otal
ment (fundamental power) factor cos ~ without filter,
where ~'~t~ filter is the angle between the funda-
mental voltage Vphase = VphaseZ0 ~ and the total fun-
damental phase current. Hint: For calculation of
Itotalphase yOU may:
9 use a (per-phase) phasor diagram and perform
calculations using the cosine law (see Fig.
P1.12.2): a 2 = b 2 + c 2- 2. b. c. cos (or,)
9 draw the phasor diagram to scale and find
Itotalphase by graphical means, or

55. Other documents randomly have
different content

56. Commercial
Panic.
Samuel Lawrence.][From a
Crayon Drawing.
WILLIAM MAKEPEACE
THACKERAY,
1811–1863
Thackeray, whose
father was in the Indian
Civil Service, was born
at Calcutta and
educated at the
Charterhouse and
Cambridge. He studied
in Paris as an artist, but
took to literature and
Sir W. Gordon.][From an Engraving.
LORD MACAULAY,
1800–1859.
Thomas Babington Macaulay
was the son of Zachary
Macaulay the philanthropist.
Educated at Trinity College,
Cambridge, he was called to the
Bar in 1826. In 1834 he went to
Calcutta as a member of the
Supreme Council; on his return
The Orsini Plot.
CHAPTER XI.
1858–1860.
Commercial Panic in London—Suspension of the Bank Charter Act—The Orsini Plot—The Conspiracy to
Murder Bill—Defeat and Resignation of the Government—Lord Derby’s Second Administration—
Disraeli’s Reform Bill—Vote of No Confidence—Defeat and Resignation of the Government—Lord
Palmerston’s Second Administration—Threatened French Invasion—The Volunteers—The Paper Duty
Repealed by the Commons and Restored by the Lords—A Constitutional Problem—Its Solution—War
with China—British and French Defeat at Pei-ho—Return of Lord Elgin to China—Wreck of the Malabar
—Capture of the Tangku and Taku Forts—Occupation of Tien-tsin—Murder of British Officers and
others—Capitulation of Pekin—Destruction of the Summer Palace—Treaty with China.
ALMERSTON’S Government, apparently one of the most popular that had ever
been formed, had to bow under the adverse influence of events beyond its
control. In addition to the commotion radiating from the
centre of disturbance in India, there had been widespread
commercial disaster at home, following on a period of excited
speculation. On November 12 the Bank Charter Act had been suspended, and the Bank of
England received authority to exceed the statutory limits in meeting demands for discount
and advances, because of the numerous failures and prevailing money-panic.
But the squall that
was to overturn the
Ministry came from a quarter which
nobody could have foreseen. On
January 14 a murderous attack was
made on the Emperor and Empress of
the French in Paris. An Italian refugee,
Felice Orsini, well known in England,
waited, with a number of fellow-ruffians,
at the door of the Opera House in the
Rue Lepelletier, and threw three bombs,
charged with a powerful explosive, at
the Imperial carriage as it drew up. The
effect was appalling: the intended
victims escaped unhurt, but ten persons
were blown to death among the
bystanders, and no less than 156 were
wounded, of whom Orsini himself was
one. All this was dreadful enough, and
yet the connection thereof with the

57. wrote for Fraser’s
Magazine and (from
1842) for Punch. It was
not until 1847 that,
with the publication of
“Vanity Fair,” he
became a serious
competitor for popular
favour with Dickens. In
1859 he became the
first editor of the
Cornhill Magazine.
he became Secretary at War,
and, in 1846, Paymaster to the
Forces. His “Essays” began to
appear in the Edinburgh Review
in 1825; his “Lays of Ancient
Rome” were published in 1842.
He was engaged on the final
chapters of his “History of
England” when he died, in 1859.
He was raised to the peerage in
1857.
KANDY LAKE, CEYLON.
The Island of Ceylon has a population
exceeding 3,000,000. Its principal product is tea,
of which in 1896 over 100,000,000 lbs. were
exported. The chief town is Colombo. Kandy,
situated on a beautiful lake in the interior, was the
capital of the native kingdom before its annexation
by the British in 1815.
Government
Defeat and
Resignation.
stability of Palmerston’s Administration
might seem exceedingly remote. It was
established in the following way. Orsini,
a man of good birth and attractive
exterior, had been very well received in
English society, and his appeals on
behalf of the Italian provinces of Austria
had received polite attention, and,
among enthusiastic advocates of
freedom, a great
deal of sympathy. London was then, as it
remains to this day, a sanctuary for political
refugees from all the ends of the earth.
Palmerston, however, had enough common-
sense and honesty to recognise that it was one
thing to allow fugitives to shelter in England,
and quite another to take no precautions as to
their good behaviour, and he prepared and
introduced a Bill to strengthen the law dealing
with conspiracy to murder. This was vehemently
opposed on the first reading by Lord John
Russell, but Disraeli and the Conservatives
helped to carry that stage by a large majority.
In the interval, however, before the second
reading, public opinion had undergone a
marked change. The tone of the French Press
had become intensely insulting towards Great
Britain; people in London had got it in their
heads that the Conspiracy to Murder Bill had
been prepared at the dictation of the French Ambassador, and Palmerston was suspected
of being at his old game of truckling to Louis Napoleon. The suspicion
was fatal to him. An amendment to the second reading, moved by Mr.
Milner Gibson, was supported by Disraeli and 146 Conservatives, and
carried against the Government by a majority of nineteen. Palmerston
resigned at once, and Lord Derby began his second administration with his eldest son,
Lord Stanley, at the Colonial Office, Lord Malmesbury at the Foreign Office, and Disraeli
leading the House of Commons as Chancellor of the Exchequer.
Disraeli had once taunted Palmerston with having no domestic policy. “His external
system,” he said, “was turbulent and aggressive, that his rule at home may be tranquil
and unassailed.” That was, in truth, the greater part of the secret of Palmerston’s
popularity; he refrained from exciting apprehension and stirring combustible questions. He
made no enemies at home, though he might be careless in giving offence abroad. But
that was a rôle not at all suited to Disraeli’s ambition. He knew that at any moment
something might happen to drive his party out of office, and he resolved to prepare a soft
place to fall on. It would be a fine stroke to take Lord John Russell’s favourite project out
of his hands, to “dish the Whigs” by lowering the franchise. John Bright had returned to

58. R. Simkin.]
A. Gunner, Artillery.    B. Sapper, Engineers.   
C. Officer Queen’s Westminster.    D. Officer,
Victoria Rifles.    E. Priv ate, Six-foot Guards.   
F. Private, Artists.
UNIFORMS OF VOLUNTEERS, 1860.
R. Simkin.]
A. Private, London Rifles.    B . Gunner, Artillery.   
C. Sapper, Engineers.    D . Officer, 1st Middlesex.   
E. Officer, and V.B. Royal Fusiliers.    F . Private,
Artists.    G. Priv ate, London Scottish.
UNIFORMS OF VOLUNTEER BATTALIONS, 1897.
Disraeli’s Reform
Bill.
H. Edridge, A.R.A.]
[National Portrait Gallery.
ROBERT SOUTHEY, LL.D.,
1774–1843.
Poet Laureate 1813–1843.
active
politic
s and
was
stirrin
g up
the
peopl
e in
the
north
to
agitat
e for
Refor
m. He
would
take the wind out of Bright’s
sails too; and he persuaded
Lord Derby to let him bring in
a Reform Bill of his own.
It was an unlucky device. The Bill was not a very
formidable one, but it disturbed a great question. Two
members of the Cabinet, Mr. Walpole and Mr. Henley, threw up
their offices rather than join in work which they, in common
with most Conservatives in the country, considered alien from
Conservative principles. The Whigs and Radicals would have
no hand in such a measure, which they exposed as a sham,
and Russell persuaded the House to reject it by a majority of
thirty-nine. Neither did the Bill serve its author’s purpose in
the country. When Lord Derby appealed to the constituencies,
the response came, at the end of May 1859, in the form of a
feeble accession to Conservative numbers, not strong enough
to avert defeat by thirteen votes on a vote of want of
confidence, moved by a young member put up by the
combined Whigs, Radicals, and Peelites—the Marquis of
Hartington (now Duke of Devonshire). The only effects of
Disraeli’s stratagem had been to disgust and disunite his own
party, and to cause his opponents to sink their differences in
united action.
On Lord Derby’s resignation, Lord Palmerston formed a strong Cabinet, including Lord
Granville, Mr. Gladstone, Sir George Cornewall-Lewis, Mr. Sidney Herbert, and Mr.
Cardwell. Lord John Russell refused any post except that of Foreign Secretary, which shut
out Lord Clarendon, who declined any other appointment. At the moment, as it happened,
England was keeping scrupulously clear of the conflict between France and Austria. The

59. H. W. Pickersgill, R.A.]
[National Portrait
Gallery.
WILLIAM WORDSWORTH,
1770–1850.
Poet Laureate 1843–1850.
G. F. Watts, R.A.][From Photo by
H. H. Cameron.
LORD TENNYSON,
1809–1892.
Appointed Poet Laureate
1850. His first published
verses appeared in a volume
of “Poems by Two Brothers”
in 1827. He was created
Baron Tennyson in 1884.
Lord
Palmerston’s
Second
Administration.
Threatened
French Invasion.
The Volunteers.
Queen’s speech to
the new
Parliament had
announced that “a
strict and impartial neutrality” should
be maintained, and this was done in
spite of persistent attempts on the
part of Louis Napoleon to secure the
assistance of Great Britain in the
deliverance of Italy, in spite, too, of
the strong sympathy entertained by
Mr. Gladstone and others in the
Cabinet for the cause of Italian
nationality. There was, however, a
shrewd distrust of the French
Emperor growing in the minds of the
British public at this time, which
made it easier than it had otherwise
been for the Government to steer
clear of foreign complications. In fact, the
development of the arsenal at Cherbourg and the assembly there of a
powerful fleet were interpreted, perhaps not without justice, as
indicating a contemplated invasion of England. The Volunteer movement first assumed
important proportions in the year 1859 under this feeling of apprehension.
“Form, form, riflemen, form!
Ready—be ready, to meet the storm”—
sang the Laureate, and the storm was expected to come from the French quarter.
However, whatever aggressive intentions may have passed through the mind of Napoleon
III. were dissipated by the formidable front assumed by the people of Great Britain. The
immense improvement which had been recently effected in arms of
precision caused irregular troops to assume far greater importance in
the calculations of an intending invader than they ever had before; and the same cause,
by encouraging fine marksmanship and developing competitive skill at the targets, has
imparted to the Volunteers of 1859 a permanence quite without precedent in the history
of similar martial movements.
Mr. Gladstone’s Budget of 1860 contained a proposal which brought about his final
rupture with the Conservative party. He proposed to repeal the paper duty. Now the
burdens upon journalism, originally imposed with the deliberate intention of limiting the
number and regulating the political character of newspapers, had already been greatly
reduced since the beginning of the reign. The stamp duty had stood at a penny on each
copy of a newspaper till 1855, when it was abolished; but there remained still a pretty
heavy tax on paper. Mr. Gladstone’s proposal to abolish it was met with strong opposition
from all sections of politicians, and, strangely enough, from paper manufacturers
themselves, as well as from the proprietors of high-priced journals. There was, besides, a

60. G. F. Watts, R.A.]
[National Portrait
Gallery.
ROBERT BROWNING,
1812–1889.
Poet. His last volume,
“Asolando,” was published on
the day of his death,
December 12, 1889. He and
Tennyson lie in adjoining
graves in “Poet’s Corner,”
Westminster Abbey.
Question of the
Paper Duty.
J. Phillip, R.A.] [By permission of Messrs. Graves, Pall Mall.
vague, but very general, dread of the effect on
the public mind of the multiplication of cheap
literature. Nevertheless, the Budget
Resolutions removing the paper tax passed through Committee,
though the last of them was only carried by a majority of nine
votes. At the present day, the Chancellor of the Exchequer’s
proposals, having passed through that ordeal, would be
regarded as impregnable. It was otherwise in 1860. Lord
Lyndhurst, then in his eighty-ninth year, and so frail in body that
a rail had to be fixed opposite his seat to support him in
speaking, joined the opposition raised in the House of Lords to
the repeal of the paper tax, and made a marvellously vigorous
and effective attack on the proposal. The Lords vetoed the
repeal by a majority of eighty-nine.
THE HOUSE OF COMMONS IN 1860.

61. A Constitutional
Problem.
1. Rt. Hon. Edward Ellice.
2. Rt. Hon. Sir Francis T. Baring.
3. Lord H. G. Vane.
4. Richard Cobden, Esq.
5. John Bright, Esq.
6. Lord Elcho.
7. Rt. Hon. Edward Cardwell, Chancellor of the Duchy of Lancaster.
8. Sir Roundell Palmer.
9. Rt. Hon. Milner Gibson, President of Board of Trade.
10. Rt. Hon. Charles Pelham Villiers, President of Poor Law Board.
11. W. Massey, Esq.
12. Viscount Palmerston, First Lord of the Treasury.
13. Sir Denis Le Marchant, Bart.
14. Rt. Hon. the Speaker.
15. Thomas Erskine May, Esq. C.B.
16. Lord Charles Russell.
17. Mr. Lee.
18. Rt. Hon. Sir John Pakington.
19. Sir Hugh M’Calmont Cairns.
20. Col. J. W. Patten.
21. Rt. Hon. Sotheron Estcourt.
22. Lord John Manners.
23. Sir Edward Lytton Bulwer Lytton, Bart.
24. Rt. Hon. Major-General J. Peel.
25. Lord Stanley.
26. Rt. Hon. B. Disraeli.
27. Rt. Hon. Spencer H. Walpole.
28. Rt. Hon. J. W. Henley.
29. Lord John Russell.
30. Rt. Hon. W. E. Gladstone, Chancellor of the Exchequer.
31. Rt. Hon. Sir George Grey, Secretary of State.
32. Rt. Hon. Sir Charles Wood, Bart., Secretary of State for India.
33. Rt. Hon. Sir George Cornewall Lewis, Bart., Secretary of State for War.
Ministerialists were very indignant; the House of Lords had violated the Constitution;
they had refused to sanction the repeal of a tax ordered by the House of Commons, and
thereby infringed the privileges of that Chamber. The next step would
be that the Lords would claim the right of imposing taxation—the
cherished monopoly of the House of Commons. It was certainly an

62. Commander A. T. Thrupp.] [From Sketches made on the spot.
War with China.
HONGKONG AND ITS HARBOUR.
Hongkong is the principal centre of British
trade with China. Ceded to Great Britain 1842.
awkward question, but Palmerston was equal to the occasion. He averted a popular storm
by moving for a Select Committee to examine and report on the degree, if any, in which
the Lords had exceeded their powers. The Committee sat for two months, and reported
that no breach of privilege was involved in the refusal of the Lords to ratify the repeal of a
tax. It was not the re-imposition of a tax, for, although the Lords have no power to
impose taxation, a tax can neither be repealed or imposed without the concurrence of
both Houses. In the end the difficulty was got over by Palmerston, who moved certain
resolutions affirming the exclusive right of the House of Commons to impose or remit
taxation.
ATTACK ON FORTS ON THE PEI-HO RIVER, May 20, 1858.
The Chinese had completed batteries and earthworks armed with eighty-seven
guns, and had obstructed the river with junks chained together. The British and
French squadrons forced a passage, and the Plenipotentiaries (Lord Elgin and Baron
de Gros) proceeded to Tien-tsin and opened negotiations. The Treaty then obtained
was to be ratified at Pekin within twelve months; but the Plenipotentiaries appointed
in accordance with this clause met, in June 1859, a still more determined resistance.
Serious trouble had
broken out again between
Great Britain and China. Mr. Bruce, brother to
the Earl of Elgin, had set out for Pekin as British
Plenipotentiary, in company with the French
Plenipotentiary, as provided by the Treaty of
Tien-tsin. They were escorted by a squadron,
chiefly consisting of gunboats, under Admiral
Hope; but on arriving at the mouth of the Pei-
ho they found the passage obstructed by booms
and defended by recent fortifications. As the
authorities at Tien-tsin returned evasive
answers to the Admiral’s remonstrances, he
determined to force a passage. The gunboats
advanced up the Pei-ho on June 24, when suddenly a tremendous fire was opened on
them from masked batteries in the forts. The Kestrel was sunk, the Lee had to be run
ashore to avoid sinking, the Plover, which carried the Admiral’s flag, was disabled, so that

63. From a Photograph] [by Notman & Sons, Montreal.
QUEBEC.
The Capital of the former province of Lower
Canada is largely inhabited by people of French
descent, and French is currently spoken.
From a Photograph] [by Notman & Sons, Montreal.
MONTREAL.
This is the largest town in Canada; population
(1891), 216,650. On the extreme right of the
picture can be seen three or four spans of the
Victoria Tubular Bridge, nearly two miles long,
crossing the St. Lawrence river.
THE CANADIAN HOUSES OF PARLIAMENT,
OTTAWA.
The government of Canada is (under the
Sovereign) vested in a Governor-General and a
Privy Council, and the legislative power is
exercised by a Parliament of two Houses, called
the “Senate” and “House of Commons.” Canada
has an area of 3,315,000 square miles, and a
population of over 5,000,000 (4,833,239 in
1891).
Wreck of the
“Malabar.”
he had to shift his flag to the Cormorant, and
the Admiral himself, being severely wounded,
had to hand over the command to Captain
Shadwell. It was determined to make an
immediate attempt to carry the forts by assault.
A body of 1,000 men, including sixty French,
were landed at 7 p.m., but, owing to the mud,
which was knee, and even waist-deep, only
about fifty men succeeded in reaching the
furthest of three ditches surrounding the south
fort. Their ammunition was wet, all the scaling
ladders, except one, either had been broken by
the tremendous fire from the fort or had stuck
in the mud. Ten brave fellows rushed forward
with this one, but three of them were shot dead
at once, and five were desperately wounded.
There was nothing for it but retreat. The loss in this disastrous affair was eighty-nine
officers and men killed and 345 wounded.
Of
course
such a
treache
rous
act
could
not go
unpunis
hed. An
ultimat
um was
sent
deman
ding an
apology
and the
fulfilme
nt of the Treaty of Tien-tsin, including the
payment of the war indemnity of 4,000,000 taels.
Lord Elgin and Baron Gros, the Plenipotentiaries
who acted for the Allies in the Treaty of Tien-tsin,
proceeded to Hongkong to enforce the demands
of England and France, supported by an army under Sir Hope Grant, in which several Sikh
regiments volunteered to serve, and a French contingent under General Cousin de
Montauban, afterwards distinguished as Comte Palikao. The Plenipotentiaries came near
to perishing on the voyage out. The Malabar frigate, which conveyed
them, was totally wrecked on a reef at Point de Galle, in Ceylon, those

64. Occupation of
Tien-tsin.
Murder of British
Officers and
others.
From a Photograph] [by Notman & Sons, Montreal.
TORONTO.
Capital of Ontario, and the second largest
town in Canada.
Capitulation of
Pekin.
on board escaping with great difficulty, and with the loss of many valuable papers and
much property. However, Lord Elgin and Baron de Gros arrived at Hongkong in another
vessel on July 21. They found that the Chinese Council had returned an insolent answer to
Mr. Bruce’s ultimatum, which left no alternative but immediate action. The Allied Forces
advanced on July 26, the English from Chefow, and the French from Tah-lien-hwan; they
captured the Tangku Forts, with forty-five guns, on August 14, and the Taku Forts,
containing about 400 guns, on the 20th, the English loss on the latter occasion amounting
to seventeen killed and 183 wounded. Sir Hope Grant’s despatches contain cordial
references to the gallantry displayed by his French allies in the assault. Tien-tsin was next
occupied on August 23, and preparations were made for an immediate advance on Pekin.
The Chinese forces had disappeared, but the Government, anxious at all
hazards to keep the “barbarians” from approaching the capital, opened
negotiations for peace, and on September 13 Lord Elgin’s secretaries,
Mr. Parkes and Mr. Loch, with Mr. Bowlby, the Times’ correspondent, and some British and
French officers, rode on to Tungchow a town within twelve miles of Pekin, to arrange the
preliminaries of an interview between the Plenipotentiaries of the Allies and the Chinese. A
camping ground was allotted for the Allied Forces about five miles short of Tungchow, but
before Grant and de Montauban could occupy it, a large Chinese army had surrounded the
position. Mr. Parkes, Mr. Loch, and their party, protected by a flag of truce, went back to
Tungchow to remonstrate against this dangerous violation of the agreement; they were
treacherously seized and thrust into loathsome dungeons, crowded with filthy Chinese
prisoners, where thirteen out of twenty-six of them died from savage ill-treatment by their
captors. Captain Brabazon, R.A., Lieutenant Anderson, and Mr. Bowlby
were among these victims, their hands and feet having been so tightly
bound with cords that the flesh burst and fatal mortification ensued.
The Allied Army resumed its march on
Pekin; the Emperor’s Summer Palace, a
magnificent collection of buildings, treasure-
houses, and gardens, was taken on October 6;
on the 12th everything was ready for the
bombardment of the capital, and it was made
known to the Chinese Government that this
would begin the following day at noon, unless
the city were surrendered previously. The
Emperor had fled, but on the
morning of October 13 the
Governor of Pekin capitulated.
The Allies entered, and before noon the English
and French ensigns were flying side by side on
the citadel.
Not till then did Lord Elgin learn the horrible
fate of the captives. He decided at once that exemplary vengeance must be inflicted, but
not according to the traditional custom of reprisals, by inflicting torture and death on the
persons of individuals. No doubt the Chinese officials would have handed over to him as
many vicarious victims as he chose to demand, but Lord Elgin decreed such a
monumental act of indignation as should never be effaced from the memory of the people

65. VANCOUVER HARBOUR, BRITISH COLUMBIA.
The western terminus of the Canadian Pacific
Railway, and the principal port on the Pacific coast
of British North America.
EMERALD LAKE, IN THE CANADIAN ROCKY
MOUNTAINS.
The Canadian Pacific Railway, in passing over
the “Rockies,” opens up some of the finest scenery
in America.
THE CITY HALL, WINNIPEG.
Manitoba is a district of
enormous farms. The Capital,
Winnipeg—known as Fort Garry
until its incorporation in 1873—is
one of the “newest” cities in the
British Empire. Its population in
1871 was 241; in 1891, 25,642. It
is the centre for the distribution of
the produce of Western Canada.
Destruction of
the Summer
Palace.
of
China.
The
Summ
er
Palace
was
the
most
precio
us
posse
ssion
of the Heavenly
Dynasty. Therein
had been stored
the best of the art
treasures of many generations; the ingenuity of architects,
gardeners, and craftsmen of all kinds had been exhausted in
erecting and decorating its courts and pagodas and laying
out the fantastic grounds. Lord Elgin ordered its total
destruction. The French and English
soldiers were allowed to plunder it first;
jewellery, plate, and other costly articles
were “looted” in immense quantity, and
then the whole vast edifice was delivered to the flames. A
monument was set up on the site, bearing an inscription
that this was done as the punishment for national cruelty
and treachery. A Convention between the British and
Chinese Plenipotentiaries was concluded on October 24, and
Pekin was evacuated by the Allied troops on November 5.

66. G. H. Thomas.] [From the Royal Collection.
Carl Haag, R.W.S.] [From the Royal Collection.
HER MAJESTY AND THE PRINCE CONSORT AT A REVIEW AT ALDERSHOT, June 1859.
On the left is General Knollys, afterwards Comptroller of the Household to the Prince
of Wales, in command of the troops.
THE QUEEN AND PRINCE CONSORT FORDING THE POLL TARFF, October 9, 1861.
The story of this, the last excursion taken by the Queen in company with the
Prince Consort, is told in a very interesting chapter of Her Majesty’s “Leaves from the
Journal of our Life in the Highlands.” On the previous night the Royal party had
stayed, unexpected and unrecognised, at the inn of Balwhinnie, “where,” says Her
Majesty, “there was hardly anything to eat; only tea and two miserable starved
Highland chickens, without any potatoes; no pudding, and no fun.” But in this last
particular the succeeding day’s exploits certainly cannot have been deficient.

68. The American
Civil War.
CHAPTER XII.
1861–1865.
The American Civil War—Recognition of Confederate States as Belligerents—English Opinion in Favour of the
Confederates—The Trent Affair—Dispatch of Troops to Canada—Death of the Prince Consort—His Last
Memorandum—The Cruiser Alabama—Claims against Great Britain—Arbitration—Award Unfavourable
to Great Britain—Public Indignation—Marriage of the Prince of Wales—The Schleswig-Holstein Difficulty
—Neutrality Observed by Great Britain—Popular Sympathy with Denmark—Dissolution of Parliament—
Result of the Elections—Death of Lord Palmerston.
HE election of Abraham Lincoln as President of the United States, and the
consequent decree abolishing slavery, brought about the secession of the
Southern States and the outbreak of civil war on a vast scale early in 1861. It
was not to be expected that such a convulsion among people of British
speech and descent could run its course without taking effect on a
country so intimately associated with the United States as Great Britain
was in commerce, literature, and social relations. The first difficulty arose out of the
question whether the Southern States—the Confederates, as they were designated—
should receive recognition as belligerents, or whether they should be regarded as rebels
against the Federal Government. Lord John Russell, having consulted the law officers of
the Crown, announced on May 8 that the Government had decided to recognise the
belligerency of the Southern Confederation, and a proclamation of neutrality was issued
on May 13. This act was interpreted as unfriendly by the Federal Government, who
claimed that no State in the Union had a constitutional right to secede, that it could only
rebel, and that the British Government had unduly favoured the rebels by prohibiting Her
Majesty’s subjects from enlisting in the service of either Federals or Confederates. On the
other hand, the Northern or Federal Government had proclaimed the blockade of the
Southern ports, thereby implying that Confederates were belligerents and not rebels, for
no Government can blockade its own ports, it can only close them. So far, therefore, from
favouring the Confederate cause by recognising its belligerency, Her Majesty’s
Government adopted the only course enabling them to respect the Federal blockade and
to restrain English traders from breaking it.
But for some occult reason, the Federal cause was unpopular in this country from the
beginning; the initial reverses sustained by the armies of the North were hailed with
satisfaction in the English Press; and this, combined with a rash expression used in public
by Lord Palmerston about the “unfortunate rapid movements” of Federal troops in the
action at Bull’s Run, caused a very sore feeling against Great Britain among both leaders
and people in the Northern States.

69. F. Winterhalter.]
[From the Royal Collection.
H.R.H. EDWARD, DUKE OF KENT,
1767–1820.
Fourth son of King George III., and
father of Her Majesty Queen
Victoria.
F. Winterhalter.] [From the Royal Collection.
H.R.H. VICTORIA MARIA LOUISA,
DUCHESS OF KENT.
H.R.H. the Duchess of Kent was the
daughter of H.S.H. Francis, Duke of
Saxe-Coburg-Saalfeld; married July 11,
1818, Edward, Duke of Kent, fourth son
of George III., and was the mother of
Her Majesty Queen Victoria. Died March
16, 1861. Her Majesty, therefore, lost
both mother and husband within nine
months.
The “Trent”
Affair.
An unfortunate incident arose early in the war to
intensify this feeling, and the corresponding
unpopularity of the Federals in England. Jefferson
Davis, President of the Confederate States, being
anxious to obtain recognition by European Courts, sent
two Envoys, Mr. Mason to represent him at the Court of
St. James’s, and Mr. Slidell at the Court of the Tuileries.
These two gentlemen, escaping by night from Charleston, then under blockade, embarked
at Havana in the English mail steamer Trent. A Federal sloop-of-war was
cruising about in search of the Confederate privateer Sumter, and her
commander, Captain Wilkes, on hearing about the Confederate Envoys,
resolved to get possession of them. Intercepting the Trent in the Bahama Channel, he
hailed her to heave to, fired a couple of shots across her bows, boarded her, and carried
off Messrs. Mason and Slidell. Of course this act was wholly unjustifiable by international
law, and President Lincoln at once directed Mr. Seward to reply by complying with Earl
Russell’s demand for the surrender of the Confederate Envoys. They were liberated
accordingly on January 1, 1862, and sailed for Europe. But unluckily Lord Palmerston had
no reason to calculate on this ready compliance with British demands. Captain Wilkes had
received approval of his conduct from the Federal Secretary to the Navy, a vote of thanks
to him had been passed by the Washington House of Representatives, and he had been
fêted wherever he went. All this was taken as indicating President Lincoln’s intention to
defend the action of his officer: indeed, but for what was going on in England, Lincoln’s
best intentions might have been overborne by the tide of public opinion. Simultaneously

70. Death of the
Prince Consort.
THE HAWKESBURY BRIDGE, NEW SOUTH
WALES.
On the railway between Adelaide and Brisbane;
the largest work of the kind south of the
Equator. Opened May 1, 1889.
with the despatch of Lord John Russell’s demand for the surrender of the prisoners, 8,000
troops were embarked in England for service in Canada, and every preparation was made
for immediate war. This not only cost Great Britain about a million of money, but also
deprived President Lincoln’s act of all grace in the eyes of English people.
SYDNEY TOWN AND HARBOUR, FROM PALACE GARDENS.
The colony of New South Wales, originally comprising the eastern half of the
continent of Australia and the island of Tasmania, was formally founded by an
expedition under the command of Capt. Arthur Phillip. The first landing was effected
at Botany Bay, and the City of Sydney was founded on January 26, 1788. New South
Wales became a self-governing colony in 1855. Population (1893), 1,277,870; imports
(1895), £15,992,415; exports (1895), £21,934,785.
The Trent difficulty was the last public question in which the Prince Consort was to
take part. A memorandum dated December 1, 1861, written by him and conveying to Lord
Russell the Queen’s remarks on the drafts of despatches he was about to forward to Lord
Lyons, was the last State paper to which the Prince Consort set his hand. He had been ill
for some days previously, and soon afterwards gastric fever developed itself. In spite of
the tender attention of the Queen and the Princesses, the malady continued, not much
worse, apparently, but no better. Congestion of the lungs set in, and at
midnight on Saturday, December 14, the tolling of the great bell of St.
Paul’s Cathedral announced to the people of London that the Monarch’s
Consort was no more—that their Queen was a widow.

71. THE TOWN HALL, CENTENNIAL
HALL, AND CATHEDRAL, SYDNEY.
W. Theed.] [At Windsor Castle.
THE QUEEN AND PRINCE CONSORT.
The Prince died in his forty-third year. It is pretty
well understood by this time how well he had
discharged the duties of a difficult station as Consort
of the Crown, how true was the love which united
him to the Queen, how deep was her sorrow at
parting with him after twenty-one years of wedded
life. He had lived down the prejudice which
undoubtedly was prevalent at the time of, and for
some years after, the marriage. Without appearing in
political affairs with such prominence as might have
aroused the susceptibilities of a self-governing
people, his attention to public affairs was as
incessant as that of any Cabinet Minister. The writing
tables of the Queen and the Prince stood side by
side; he was ever at hand to advise Her Majesty in
her correspondence with Ministers; many of her
letters and memoranda to the Cabinet are in the
Prince’s handwriting. When the final solution of the
Trent dispute was communicated to Her Majesty on
January 9, 1862, she wrote to the Prime Minister:
“Lord Palmerston cannot but look on this peaceful
issue of the American quarrel as greatly owing to her
beloved Prince, who wrote the observations on the
draft to Lord Lyons, in which Lord Palmerston so
entirely concurred. It was the last thing he ever wrote.”

72. ALBERT MEMORIAL,
KENSINGTON GARDENS.
This monument, which is of
marble, gold, bronze, and mosaic
work, was designed by Sir G.
Gilbert Scott, R.A., and is 175
feet high. The statue of the
Prince, of bronze gilt, is by Foley.
Above the arches runs this
inscription: “Queen Victoria and
her people to the memory of
Albert, Prince Consort, as a
tribute of their gratitude for a life
devoted to the public good.” The
cost of the Memorial exceeded
£130,000.
The Cruiser
“Alabama.”
ROYAL ALBERT HALL, KENSINGTON GORE.
So named in memory of the Prince Consort,
whose Memorial it faces. It was opened by the
Queen in 1871. The Hall itself is oval, 200 feet
The only danger to the Prince Consort’s place in the affections of the British people in
his later years was of the nature of that which over-took Aristides. There is a certain
monotony in virtue, like that of uninterrupted serene weather, which weighs upon natures
of a less lofty tenour. But no sooner was the Prince departed than the nation realised the
value of the part he had performed, and it has never since ceased to be grateful for the
energy he displayed in promoting every scheme of social or intellectual advancement, and
stimulating the growth of commercial and industrial enterprise.
The next controversy endangering
friendly relations between the Governments
of Queen Victoria and President Lincoln
arose out of Confederate privateering. Many of the private
dockyards of Great Britain were turning out vessels as fast as
they could to sell to the Confederate leaders. One of these
ships, the Alabama, built in Messrs. Laird’s yard at
Birkenhead, became the terror of Federal commerce, having
captured between sixty and seventy merchantmen in two
years. At last she was sunk by the Federal ship-of-war
Kearsarge, but her fame did not perish with her; it was the
cause of an important alteration in international law. The fact
is, the Alabama was, for all intents and purposes, an English
pirate. Built and armed in England, most of her crew and all
her gunners were English, some of the latter being actually
in English pay, as belonging to the Royal Naval Reserve. She
approached her prizes flying the British colours at her peak,
and only hauled them down when her prey could not escape.
She was constantly in English harbours, and never in a
Confederate one. While she was being built at Birkenhead,
the American Minister appealed in vain to the British
Government to detain her under the Foreign Enlistment Act;
she was allowed to go to sea. Later on, two ironclads were
on the point of leaving the Mersey for the Confederate
service. Again Mr. Adams, the American Minister, demanded
their detention, adding in his letter to Lord Russell, “it would
be superfluous in me
to point out to your lordship that this is war.” The
ironclads were detained, but President Lincoln,
Earl Russell, and Lord Palmerston had all passed
away before the dispute about the Alabama was
brought to a close. The American civil war had
ended, General Grant was President of the United
States, and Mr. Gladstone Prime Minister of
England, when the question came up for final
settlement. When it had been raised first, Lord
Palmerston’s Government had refused to admit
any responsibility; then followed Lord Derby’s third
administration in 1866, and Lord Stanley as

73. by 160 feet, and 140 feet high to the dome. It
accommodates 10,000 persons, and cost
£200,000.
Foreign Secretary consented to the proposal for
arbitration. But the introduction of various claims
on the part of private individuals, arising out of
events long antecedent to the civil war caused the
postponement of any agreement until the year 1871. Each nation then appointed a
Commission to meet at Washington to discuss all the subjects of international controversy,
of which the Alabama claims were the principal. The British Commissioners were Earl de
Grey (the present Marquis of Ripon), Sir Stafford Northcote (afterwards Earl of
Iddesleigh), Mr. Montague Bernard, Sir Edward Thornton, British Ambassador at
Washington, and Sir John Macdonald, Prime Minister of the Canadian Parliament. The
Conference resulted in the Treaty of Washington, of which the opening clause gave
occasion to considerable resentment in the minds of the British public. It was no less than
an apology—dignified but explicit—on the part of the Queen’s Government, for having
permitted the escape of the Alabama and other cruisers from British ports, to the injury of
American commerce. England, it was loudly protested, had never apologised to any other
Power; she would never had been so humiliated had “Old Pam” remained at the head of
affairs; the whole British case had been given away before the matter got to the stage of
arbitration. So said the British Press, and so said a large section of the public. However,
Great Britain having professed herself ready to pay something to secure the friendship of
President Grant’s Government, the claims went before a tribunal of five arbitrators, of
whom one was appointed by Queen Victoria, and one each by President Grant, the King of
Italy, the Emperor of Brazil, and the President of the Swiss Confederation. This tribunal
assembled at Geneva in 1872, and decreed that Great Britain should pay an indemnity of
£3,250,000 for the acts of the Alabama and other Confederate cruisers. The fine was paid,
but the impression produced on the minds of the British people cannot be said to have
been favourable to the doctrine of arbitration. It was felt that John Bull had been made to
“knuckle down” to Brother Jonathan, and the amicable intentions of the British
Commissioners at Washington of promoting cordial relations between the British and
American peoples were frustrated almost as thoroughly as they might have been had the
dispute been fought out in the ordinary way.

74. G. H. Thomas.] [From the Royal Collection.
Marriage of the
Prince of Wales.
MARRIAGE OF H.R.H. PRINCESS ALICE TO H.R.H. PRINCE LOUIS OF HESSE IN THE
DRAWING ROOM AT OSBORNE, July 1, 1862.
On the left are Her Majesty the Queen, the Prince of Wales, Prince Alfred, and
Prince Leopold, and Ernest, Duke of Saxe-Coburg and Gotha, attended by the
Duchess of Wellington and the Duchess of Athole. On the right are the parents and
brother of the bridegroom. The bridesmaids were Princesses Helena, Louise, and
Beatrice, and Princess Anna of Hesse.
On March 10, 1863, took place the marriage of Albert Edward, Prince of Wales, to the
Princess Alexandra
H
, eldest daughter of Prince Christian of Schleswig-Holstein-
Sonderburg-Glucksburg, heir to the throne of Denmark. The
announcement of the betrothal had been favourably received in Great
Britain, but, on the arrival of the bride-elect in London, her exceeding
personal beauty, her charm of manner and amiability, produced a remarkable effect, and
public feeling rose to a very high degree of enthusiastic approval. London hastened to
cover up the dingy traces of an English winter with gay bunting; the lively Danish national
colours, scarlet and white, draped all the thoroughfares; and everywhere might be seen
the Dannebrog—the national ensign of Denmark—streaming side by side with the British
standard in the keen wind and bright sunshine of March.

75. G. W. Thomas.] [From the Royal collection.
THE MARRIAGE OF H.R.H. THE PRINCE OF WALES TO H.R.H. PRINCESS ALEXANDRA
OF DENMARK IN ST. GEORGE’S CHAPEL, WINDSOR, March 10, 1863.
Her Majesty the Queen occupies the royal closet above the group of bridesmaids.
Next the Prince of Wales are his supporters, the Duke of Saxe-Coburg and Gotha, and
the Crown Prince of Prussia. The Archbishop of Canterbury and Dean Wellesley
officiate. The bridesmaids were the Ladies Victoria Scott, Diana Beauclerk, Elena Bruce,
Victoria Howard, Emily Villiers, Agneta Yorke, Feodore Wellesley, and Emily Hare. The
English Princes and Princesses are to the left of the bridal group; the mother and
sisters of the bride to the right.
The course of events on the Continent at this time gave to the royal marriage an
appearance of political significance which, in reality, it did not possess. In olden times, no
doubt, the espousal of the heir of England to the daughter of Denmark would have
implied a political and military alliance, offensive and defensive, between the two Crowns.
But in Europe of the nineteenth century it is peoples, not princes, who hold the decrees of
peace and war. It was this very fact which, shortly after the Prince of Wales’s marriage,
seemed likely to precipitate a conflict between Great Britain and Denmark on the one side,
and Austria and Prussia on the other. Englishmen had grown proud of their beautiful
Princess, and were chivalrously disposed to take up the cause of her little country. They
forgot or did not know that it was only the adopted country of her family.
The crisis arose on the death of Frederick VII., King of Denmark. The succession, as
had been decreed by the Great Powers in 1852, devolved on the father of the Princess of
Wales, who became King Christian IX. of Denmark. There had existed between Germany
and Denmark a long-standing dispute about the possession of the Duchies of Schleswig,
Holstein, and Lauenburg. The King of Denmark was also Duke of Holstein and Lauenburg,
just as, previous to Queen Victoria’s accession, the King of England had been also King of
Hanover. But the vast majority of the population of these Duchies was purely German, and
the German Confederation had been anxious for a long time to admit them to their
common nationality. The Danish Government, on the other hand, desired to incorporate

76. R. Lauchert.] [From the Royal Collection.
H.R.H. THE PRINCESS OF WALES AT
THE TIME OF HER MARRIAGE.
The Schleswig-
Holstein
Difficulty.
From a Photograph] [by Mayall, Piccadilly.
A. Princess Helena.    B . Prince and Princess of
Wales.    C. The Queen.    D . Princess Beatrice.   
E. Prince Arthur.    F. Princess Royal.    G. Princess
Alice and Prince Louis of Hesse.
A ROYAL FAMILY GROUP.
Photographed from life on the day of the wedding
of the Prince and Princess of Wales.
GOVERNMENT HOUSE, MELBOURNE.
these provinces in the Kingdom of
Denmark. Prince Frederick of
Schleswig-Holstein-Augustenburg
disputed the succession of Christian IX.
to the Duchies in question. The Germanic Diet, under the
influence of Herr von Bismarck, supported Prince
Frederick’s claim, and an allied army, provided by Austria
and Prussia, crossed the frontiers of Holstein and
Schleswig to enforce it. The Danish army was mobilised,
and Denmark entered upon a hopeless contest—
hopeless, seeing that she, one of the weakest of
European States, was pitted against two of the most
powerful.
It must
be confessed
that the
Danes had
not
unreason
able
grounds
for
believing
they
would
not be
left to
meet
such
odds single-handed. Lord Russell had often
warned the Danish Government that unless it
respected the liberty of its German subjects,
Denmark must look for no help from England
in a conflict with the Germanic Powers. The
Danes protested that they had scrupulously
followed this advice, and there can be no
doubt that they had been encouraged to look
for the support of Great Britain if any attempt
were made to infringe legitimate Danish
authority, and that both Lord Russell and Lord
Palmerston contemplated armed intervention
between Denmark and her possible aggressors as a duty which Great Britain might have
to undertake. But Great Britain had too much at stake to risk a conflict single-handed with
Austria and Prussia, who, as Lord Palmerston wrote to Lord Russell, “could bring 200,000
or 300,000 men into the field.” England was not more bound by the Treaty of Vienna than
France was; France refused to act, and England adopted the prudent, but apparently cold-

77. Dissolution of
Parliament.
From a Photograph] [by Eyre and Spottiswoode.
THE PARLIAMENT HOUSE, MELBOURNE.
The first settlement on the site of the
present city of Melbourne was made in
1836; it is now the largest city in Australia,
with a population (1891) of 490,896. The
Colony of Victoria, of which it is the capital,
was separated from New South Wales in
1851, and received a self-governing
constitution in 1855. Population (1895),
1,181,769. Imports (1895), £12,472,344.
Exports (1895), £14,547,732.
From a Photograph] [by Eyre and Spottiswoode.
THE TOWN HALL, AND PART OF COLLINS
STREET, MELBOURNE.
Death of Lord
Palmerston.
blooded, part of looker-on. Public opinion in Great Britain ran pretty high in favour of the
Danes, and many Englishmen felt ashamed of the part their country was made to play.
They could not understand how Palmerston, of all men, could act so unhandsomely, and
perhaps the only thing that saved the Government from defeat on a vote of censure, was
that Disraeli, who moved it, shrank from advocating the only logical alternative to their
policy—a declaration of war.
The sixth Parliament of Queen Victoria was dissolved on July 6, 1865, having attained
the unusual age of six years and thirty-six days. The chief feature of the
general election which followed was the number of seats gained by the
Radicals at the expense of the remnants of the Whig party or Moderate
Liberals. Mr. Gladstone, reckoned as a Liberal-Conservative up to this time, though well
known to be inclining more and more to the policy typified by John Bright, was unseated
for Oxford University by Mr. Gathorne-Hardy (now Earl of Cranbrook), and the last tie
which attached him to the Conservatives was severed by his subsequent election for
South Lancashire.
Palmer
ston’s
appeal to
the
country
had been
answered
by an
expression
of
confidence
in him, but
that
confidence
was of a
very complex kind. The Radicals voted for him,
because, as long as he was in Parliament, no other
man could lead the Liberal party; but they distrusted
his foreign policy, and chafed at his indifference to
questions of reform. The Liberals voted for him,
because he represented exactly the views of moderate Liberalism; and the attitude of
many Conservatives was accurately expressed in a letter written by Mr. W. H. Smith,
Liberal-Conservative candidate for Westminster, to Colonel Taylor, the Whip of the
Conservative party, thanking him for the support he had received from Conservatives in
his unsuccessful contest against Mr. Mill. “I believe in Lord Palmerston,” he said, “and look
forward ultimately to a fusion of the moderate men following Lord Derby and Lord
Palmerston into a strong Liberal-Conservative party.”
But the strong link which for so long had bound the present to the
past, and acted as a check on precipitate legislation, snapped at last.
Palmerston died on October 18, 1865, aged eighty-one years, less two

78. HOUSES OF PARLIAMENT, BRISBANE.
BRISBANE.
The population of Brisbane increased between
1881 and 1891 from 31,000 to 93,000.
Queensland, of which it is the capital, was
separated from New South Wales and constituted a
self-governing Colony in 1859. It had in 1895 a
population of 460,550. Imports (1895),
£5,349,007. Exports, £8,982,600.
days,
having sat
in the
House of
Commons
for fifty-
eight
years,
which, as
Mr.
Cardwell
observed, was just one-tenth of its whole
existence. The feeling in the country was more
profound than any which had been manifested
since the death of Wellington. In the course of
these pages no attempt has been made to
palliate or conceal some of the errors of
judgment, the faults of statesmanship, even the occasional want of sincerity to Parliament
and the public which formed blemishes in his career, especially in the earlier part of the
Queen’s reign. In spite of these blots—and some of them were far from venial—he had
lived to secure the confidence of his Sovereign and the affection of her people. A great
deal of this was owing to his personal character and manner and his kindly humour. It is
no slight upon Scotsmen or Irishmen to say that the chief secret of his universal
popularity was that he was such a thorough Englishman. Some of his sayings had a much
deeper meaning than their tone of levity implied. Two of them will bear repetition here,
seeing how accurately the lapse of years has fulfilled the prediction contained in them.
Palmerston was known to be opposed to any further extension of the franchise.
Somebody once observed to him that it really would not make much difference, for the
same class of member would be returned as before. “Yes,” replied Palmerston, “the same
men will get in as before, but they will play to the shilling gallery instead of to the boxes.”
The late Earl of Shaftesbury put on record one of Palmerston’s latest sayings. Palmerston
always distrusted Mr. Gladstone as a politician, and made no secret of it. But he always
was extremely anxious for Mr. Gladstone’s return for Oxford University. “He is a dangerous
man,” he said to Lord Shaftesbury: “keep him in Oxford, and he is partially muzzled, but
send him elsewhere, and he will run wild.” This came to Mr. Gladstone’s ears, so, after his
defeat at Oxford in 1865, he opened his campaign in South Lancashire by saying to the
electors assembled in the Free Trade Hall of Manchester: “At last, my friends, I have come
amongst you.... I am come among you unmuzzled.”

79. Sir E. Landseer, R.A.] [By permission of Messrs. Graves, Publishers of the large Engraving.
THE QUEEN AT OSBORNE, 1866.
On the seat are the Princesses Helena and Louise. Her Majesty is attended by John
Brown.

80. J. Tenniel.] [From “Punch.”
RETIRING INTO PRIVATE LIFE.
Lord Brougham: “Eh, Johnny, ye’ll find
it mighty dull here!” Lord John Russell
was raised to the Peerage in 1861.
CHAPTER XIII.
1866–1872.
Mr. Gladstone’s Reform Bill—The Cave of Adullam—Defeat and Resignation of the Ministry—Retirement of
Earl Russell—Lord Derby’s Last Administration—Disturbance in Hyde Park—Commercial Panic—
Completion of the Atlantic Cable—Mr. Disraeli’s Reform Bill—Secessions from the Cabinet—The Fenians
—War with Abyssinia—Retirement of Lord Derby—The Irish State Church—Dissolution of Parliament—
Liberal Triumph—Mr. Gladstone’s Cabinet—Disestablishment of the Irish Church—Death of Lord Derby
—Irish Land Legislation—National Education—Army Purchase—The Ballot Bill—Adoption of Secret
Voting.
HE only changes in the old Cabinet, consequent
on the death of its great chief, were the
advance of Earl Russell to the Premiership and
the appointment of Lord Clarendon to the Foreign Office.
But the change in the House of Commons was as
momentous as it was abrupt. The place of its old leader—
the safe, the leisurely, the unemotional Palmerston—was
filled by the restless and ardent, the uncertain Gladstone.
The Conservatives were dispirited and anxious; they were
afraid of what the new House of Commons might be led
to do; party feeling began to acquire a new bitterness,
the offspring of fear, which was to grow more and more
intense until the final retirement of Mr. Gladstone in 1895.
The Radicals, on the other hand, were sanguine and
jubilant. Reinforced in numbers, and relieved from the
restraint which the irresistible prestige of Palmerston had imposed on their aspirations,
they felt that the moment for action had come; they had got a leader after their own
hearts, and the first thing to do was to extend the franchise. But there was
disappointment in store for them. Mr. Gladstone introduced his Bill on March 12; it pleased
nobody. The Radicals detected in it the frigid hand of the Whigs, and the moderate
Liberals, secretly detesting all schemes for a Democratic franchise, began by viewing it
coldly, and gradually drifted into opposition with the Conservatives. Its most formidable
opponent rose from the Ministerial Benches. Mr. Robert Lowe, whom an intimate
acquaintance with Australasian politics had imbued with profound distrust for Democratic
institutions, made a brilliant and fearless onslaught on the measure, and received all that
rapturous applause which is the invariable reward of a strong man turning his weapons
against his own party. Gradually he drew to himself a compact band of malcontents,
whose memory might have passed into oblivion long ere this but for a happy metaphor
employed by Mr. John Bright, who likened them to the men who gathered to David in the
Cave of Adullam. “Every one that was in distress, and every one that was in debt, and

81. The Cave of
Adullam.
KING WILLIAM STREET, ADELAIDE, SOUTH
AUSTRALIA.
In point of size, Adelaide holds the third place
among Australian cities with a population (1891)
of 133,252. South Australia now stretches right
across the continent, and has an area of 578
million acres and a population (1895) of 357,405.
It was first colonised in 1836, and constituted a
self-governing Colony in 1856. Imports (1895),
£5,680,880; exports, £7,352,742.
PERTH, WESTERN AUSTRALIA.
The Swan River Settlement was founded in 1826, and made a
separate Colony, under the name of Western Australia, in 1829. It
remained a Crown Colony until 1890, when it became a self-
governing community. Population (1897), 138,000 (estimated).
Imports (1895), £3,774,951; exports, £1,332,554.
Lord Derby’s last
Administration.
every one that was discontented, gathered themselves unto him.”
People were tickled with the illustration: straightway the Liberal
dissentients were dubbed Adullamites, and “a cave” has remained ever
since the recognised term for a group of men combining to act against their own party.
Mr. Lowe’s band proved strong enough to
kill the measure. It passed the second reading,
indeed, by a majority of five, but it perished in
Committee, and the Ministry resigned. It was
the closing scene of Earl Russell’s long career,
which somehow had missed the success which
his achievements seemed to have earned. Born
in the very holiest of holies of the Whig
sanctuary, with natural abilities far more varied,
with acquired culture far more extensive, with
greater advantages from family connection than
Palmerston could boast, and without
Palmerston’s headstrong tendencies, he never
attained more than a fraction of the influence
and popularity which Palmerston had so fully
secured. Indispensable for more than a
generation to every Whig or Liberal Cabinet, he
had become associated more with the failures
than the successes of his party, and people
ungratefully remembered him rather as the
betrayer of Denmark than as the pioneer of
Reform.
Once more it
was Lord Derby’s
fate to form a
stop-gap Administration, and no
sooner was the new Ministry
complete, early in July, than the
country suddenly threw off the
indifference it had shown to Mr.
Gladstone’s offer of an extended
franchise, and public meetings were
held all over the country vehemently
demanding Reform. It was too late
in the session, of course, to do
anything that year in Parliament, but
the agitation sufficed to show that
there was at least one weak man in the Cabinet. The Reform League summoned a
meeting in Hyde Park for the evening of July 23, which it was decided to prohibit, and
amiable, gentle Mr. Walpole, the Home Secretary, issued a notice that the Park gates
would be closed at 5 p.m. Notwithstanding this announcement, processions with bands
and banners arrived at the appointed hour, and Mr. Beales, President of the League,

82. Disturbance in
Hyde Park.
G. Magnussen.] [From the Royal Collection.
demanded admittance, which was refused. Mr. Beales was an experienced barrister, and
knew very well what he was about. He was of opinion that in denying the right of public
meeting in Hyde Park, the Home Secretary was acting beyond his powers, and, content
with asserting this right in a formal way, he intended to adjourn the meeting and claim
redress by constitutional means. But a meeting in Hyde Park, no matter for what purpose,
invariably attracts thousands of idlers and roughs, who have no part and no interest in the
question to be discussed. Mr. Beales and the earnest reformers adjourned to Trafalgar
Square and passed resolutions to their hearts’ content; but the rough and idle part of the
crowd remained about Hyde Park. The gates were strong enough to resist any pressure,
but the railings were old and frail. People climbing on them felt them
shake and creak; half a dozen fellows gave a push together in Park Lane
—the railings gave way; in an instant the whole length from Hamilton
Gardens to the Marble Arch went down, and the Park was filled with a tumultuous,
rollicking mob. The grass and the flower-beds were the only property that suffered; the
police took a few prisoners, and the crowd dispersed peacefully at nightfall. Mr. Beales
took a small deputation to the Home Secretary next day, urging him to withdraw the
troops and police, and trust the people to take care of the town. Mr. Walpole consented; it
may have been prudent to do so, but the manner of doing it was unfortunate. It is a
dangerous precedent for a Home Secretary to show himself afraid of the consequence of
carrying out his own decrees.
THE MARRIAGE OF PRINCESS HELENA AND PRINCE CHRISTIAN OF SCHLESWIG-
HOLSTEIN-SONDERBURG-AUGUSTENBURG, IN THE PRIVATE CHAPEL AT WINDSOR
CASTLE, July 5, 1866.
The summer of 1866 will be remembered long in the City of London by reason of the
commercial disaster and monetary panic which followed sharply on a period of speculative
inflation, the combined result of active trade and the new law of limited liability. The
suspension early in May of the great discount firm of Overend and Gurney, with liabilities

83. Commercial
Panic.
R. Simkin.]
The Atlantic
Cable.
figured at £19,000,000, was followed within the same week by the
failure of several banks and the suspension of the Bank Charter Act. On
May 11 the Bank rate was raised to 10 per cent. and continued at that
point till August 17. The shock was one from which the credit of the country took a long
time to recover, and the amount of private misfortune and loss of income reacted on
almost every department of trade, though the public revenue maintained a surprising
degree of elasticity.
A. Private, Queensland Mounted Infantry.
B. Trooper, South Australian Cavalry.
C. Trooper, New South Wales Cavalry.
D. Trooper, Bodyguard, Canada.
E. Trooper, Canadian Dragoons (Winter Dress).
F. Private, Cape Mounted Infantry.
G. Sergeant, Cape Town Highlanders.
H. Officer, 8th Battalion Active Militia of Canada.
J. Officer, Royal Malta Artillery.
K. Trooper, Canadian Dragoons.
L. Gunner, Royal Canadian Artillery (Winter Dress).
TYPES OF COLONIAL TROOPS, 1897.
A brighter passage in the record of 1866 is that which commemorates the completion
of telegraphic communication between Great Britain and America. Attempts had been
made in 1857, 1858, and 1865 to lay a cable across the Atlantic, all of which ended in
failure; but Mr. Cyrus Field would not abandon his dream. The Great
Eastern steamship sailed from Berehaven on July 12, and on July 27 the
first messages were exchanged between the old and new worlds. A feat
hardly less inspiring was performed later in the same season, in the recovery of the
broken cable of 1865, which was spliced, thereby effecting a second connection between
the two continents.
Mr. Disraeli, as has been said, had undertaken the task in which Mr. Gladstone had
failed, and brought in a Reform Bill early in the session of 1867. It cost the Government a

84. “A Leap in the
Dark.”
From a Photograph] [by Beattie, Hobart.
HOBART, TASMANIA.
Tasmania, formerly known as Van Diemen’s
Land, was taken possession of by the British in
1803. It was governed from Sydney until 1825,
when it became an independent province; and it
received its existing Constitution in 1855. Population
(1895), 160,834; imports, £1,094,457; exports,
£1,373,063.
From a Photograph] [by Beattie, Hobart.
LAUNCESTON, TASMANIA.
heavy price at the outset: Lord Carnarvon, Lord Cranbourne (now Marquis of Salisbury),
and General Peel resigned their seats in the Cabinet because they disapproved of it. The
Bill went forward, and, after undergoing many changes, finally passed in a form conferring
household suffrage in boroughs and a £12 franchise in counties. “No
doubt,” said Lord Derby on the third reading of the Bill in the Lords,
quoting a remark made by Lord Cranbourne in the other House, “no
doubt we are making a great experiment and ‘taking a leap in the dark,’ but I have the
greatest confidence in the sound sense of my fellow-countrymen.” But another saying by
Lord Derby gives a truer insight into the real object of a Conservative Government in
doing work so repugnant to its accredited principles. Somebody having observed to him
that the measure was dangerously democratic—“We have dished the Whigs!” was all that
Derby replied. Mr. Disraeli, in reference to the same subject, made use of a phrase which
gave bitter offence to some of his party, and deepened the distrust with which the old
school of Conservatives regarded him almost to the end of his life. On October 29, 1867,
he was entertained at a banquet by the Conservatives of Edinburgh, and when passing in
review the events of the session, and especially his Reform Act, he said: “I had to prepare
the mind of the country, and to educate—if it be not arrogant to use such a phrase—to
educate our party.”
The stream of emigration westward which
set in after the Irish famine in 1848 had
resulted in creating a very large Irish
population in the United States. All these emigrants had brought with them a bitter hatred
of England, on whom they laid the blame of all the sufferings of their own people. They
had found in America the true remedy for their wrongs, which, had they realised it, arose
not so much from political, as from physical causes. By moving to a spacious land where
labour was in demand, they escaped from the evils which must always press upon a
congested population with no proper outlet for its energy. But still they loved old Ireland
and hated England, and, finding themselves of political importance in the new land, for
the Irish vote soon became indispensable to the Democratic party, they busied themselves
with projects for the deliverance of their country. They found plenty of encouragement
from Americans, for the feeling in the Northern States was very bitter against England

85. The Fenians.
From a Photograph] [by Valentine & Sons, Dundee.
WELLINGTON, NEW ZEALAND.
The first body of immigrants arrived at Port Nicholson
in 1840. In the same year the whole of the islands were
annexed by Great Britain, and Wellington and Auckland
were founded. Constitutional government was conferred
in 1853. In 1865 Wellington became the seat of
government. The population of the islands in 1895 was
698,706; imports, £6,400,129; exports, £8,550,224.
after the close of the civil war. Thousands of Irishmen had learnt the art of war and the
use of weapons in the Federal armies; a military organisation was set on foot in the belief
that Great Britain and the United States were on the point of going to war. This
organisation, which adopted the title of Fenian, had for its leader a man
of great ability and experience, James Stephens. The Government
received due warning of what was in preparation; in fact, the leaders of the movement in
Ireland openly proclaimed their intention of restoring by force of arms the independence
of Ireland. They had plenty of funds: every Irish man and maid in America contributed
something to such a glorious purpose. A steady stream of American-Irish, most of them
old soldiers of the civil war, set in from across the Atlantic, and scattered themselves
among the towns and villages of Ireland. At last Stephens himself arrived, who, having
been mixed up in the rising of 1848, was promptly arrested and lodged in Richmond
Prison, Dublin, in November, 1865. All Ireland was convulsed with delight when, a few
days later, he was found to have escaped.
The absence of Stephens from America had evil results to the Fenians there. One
party was for invading Canada, a project which Stephens had never favoured. No sooner
was his back turned, than a party of Fenians actually crossed the Niagara river, occupied a
fort, and defeated a force of Canadian volunteers. Just as in 1838, when the Canadians
were in revolt, the United States Government had saved the position for Great Britain by
enforcing the neutrality of their frontier, so now it acted a similar part, and put an end to
what might have become a highly dangerous state of affairs. Stephens never reappeared,
but the preparations he had started were continued. With the pathetic hero-worship of the
Celt, the Irish peasantry were confident that their lost leader would return among them
soon and lead them to victory. But one brief taste of prison discipline had been enough for
this doughty champion, and he is believed to have spent the rest of his life abroad in
comparative affluence, derived from the subscriptions collected from his dupes.
In February 1867 the Government
frustrated a Fenian plot to seize Chester
Castle; there was an attempt at a general
rising in Ireland, which ended in the loss of
a few lives in harebrained and
disconnected attacks on police barracks in
Cork, Limerick, Louth, and elsewhere, and
a number of American-Irish were arrested.
Two of these prisoners were being
conveyed across Manchester in a prison
van, when it was suddenly attacked by a
party of armed Fenians. A policeman was
shot dead, the prisoners were rescued and
were never recaptured.
The only other serious act of the
Fenians was an attempt to release two
prisoners confined in Clerkenwell Gaol,
who, considering the means adopted,
might very well pray to be delivered from

86. From a Photograph]
[by Valentine & Sons, Dundee.
THE PINK TERRACES, ROTOMAHANA,
NEW ZEALAND.
The water from the hot springs, on its
way to Lake Rotomahana (“Warm Lake”),
left a deposit which gradually assumed
the forms shown in the illustration. The
water was exquisitely blue; the terraces
on one side of the lake were white, on
the other a transparent pink. Both were
completely destroyed in the great
eruption of 1886.
From a Photograph][by Valentine & Sons, Dundee.
THE WHITE TERRACES, ROTOMAHANA,
NEW ZEALAND.
SIR ROBERT NAPIER,
AFTERWARDS LORD
NAPIER OF MAGDALA,
1810–1890.
Born in Ceylon.
Commander-in-Chief of
Bombay, 1865, and of India,
1870. Raised to the Peerage,
1869, for his services in
Abyssinia.
War with
Abyssinia.
their friends. A
barrel of
gunpowder,
placed against
the outer wall,
was exploded at
four in the
afternoon,
throwing down
about sixty yards
of masonry and
wrecking several
houses in the
street. But for a warning received by the Governor of
the gaol that an attempt was to be made to blow it up,
the prisoners would have been at exercise in the yard
at the time of the explosion, and almost certainly must
have been killed. As it was, twelve persons were killed
and 120 were wounded.
The
arms of a
great and
growing empire are seldom allowed to rust from disuse, no
matter how pacific the intentions of its rulers may be. Parliament
was called together in November 1867 to vote supplies for an
Expedition which it had been found necessary to send out to
Abyssinia, under the command of Sir Robert Napier. Theodore,
King of Abyssinia, a passionate and semi-barbarous despot, had
cultivated amicable relations with Great Britain for a number of
years, chiefly on account of his friendship for Mr. Plowden,
formerly English Consul at Massowah. But Mr. Plowden was dead
—killed in an encounter between Theodore and his rebellious
subjects; and Captain Cameron, who succeeded to the
Consulate at Massowah, had not succeeded in ingratiating
himself with the King. Theodore appealed to Queen Victoria to
help him against the Turks, and on receiving no immediate reply
to his letter, lost his temper and threw all the British subjects he
could catch into the cavernous dungeons of his capital, Magdala.
Among these captives was Captain Cameron. Mr. Rassam was
sent on an embassy to remonstrate with Theodore, who,
however, was not inclined to listen to reason. On the contrary,
he had the envoy seized, with his companions, Lieutenant
Prideaux and Dr. Blane, loaded with chains, and thrust into prison. Lord Stanley now sent
to demand the release of the prisoners within three months, and declared that immediate
invasion would follow if this were refused. It was a delicate business to convey despatches
to the tyrant in his rock fortress, and Theodore never received the ultimatum. The

87. From a Photograph] [by G. W. Wilson & Co., Aberdeen.
PARLIAMENT HOUSE AND TABLE MOUNTAIN,
CAPE TOWN.
See historical notes on Cape Colony, page 71.
Area, including dependencies (estimated), 292,000
square miles; population, 1,800,000, of whom
39,000 are British born; imports (1895),
£19,094,880; exports, £16,904,756, including
diamonds, £4,775,016; gold, £7,975,637; wool,
£2,000,000.
From a Photograph]
[by G. W. Wilson & Co., Aberdeen.
SEARCHING TABLES AT THE DE BEERS’
DIAMOND MINE, KIMBERLEY, SOUTH
AFRICA.
expedition set out: 400 miles of very
mountainous country had to be traversed, but
everything had been admirably prepared in the
matter of transport and commissariat, and
Napier was an experienced commander. The
ease of the victory which awaited him has done
something to diminish the fame which is really
his due for accomplishing a very difficult task.
He encountered the Abyssinian army under the
walls of Magdala on April 10, 1868; the King’s
soldiers fought with headlong gallantry, and fell
in heaps before the terrible fire of British
Infantry. Charge after charge was repelled, until
Napier found that his enemy had vanished,
leaving some 2,000 dead and wounded on the
field, while in his own force the casualties
amounted to no more than nineteen wounded.
The fierce old King so far bowed under
chastisement that the captives were released,
but he refused to surrender. It then became
necessary to enforce the lesson that, if Great
Britain does not take up arms lightly, neither does she lay them down without exacting all
her demands. Napier determined to take Magdala by assault. Perched high on a
precipitous rock, it occupied a position which, in old times and without modern appliances,
must have been pronounced inaccessible. But there are few places to which courage
equipped by science can be denied admission: the northern gate was stormed, and lying
within it was found the old lion King. Preferring death to dishonour he had perished by his
own hand.
Lord Derby’s health had given him repeated
warning that the time had come when he must seek
release from public duties. He retired from office in
February 1868, and Mr. Disraeli became Prime
Minister. “The time will come when you will hear
me.” Few—very few—who had heard that vaunt
shouted across the House in 1837 were there to
witness its complete fulfilment in 1868. It was a
position of the highest honour, but not one of great
power to which Disraeli had succeeded, and he was
not called on to occupy it long. He could not reckon
on a majority on any question upon which the
Opposition should act together under a resolute
leader. Such a question and such a leader were soon
found.
In choosing the Established Protestant Church of Ireland for attack, Mr. Gladstone
selected the weakest spot in the Constitution; one, nevertheless, which the Conservative
party were bound to defend to their last man. The Irish peasantry, except those of the

88. From a Photograph]
[by J. H. Murray, Pietermaritzburg.
TOWN HALL, DURBAN.
Durban, the largest town in Natal, had a
population in 1894 of 27,984. Natal has an
estimated area of 20,461 square miles, and
a population (1891) of 543,913. Imports,
from Great Britain (1895), £1,602,023;
exports, to Great Britain, £716,645.
The Irish State
Church.
greater part of Ulster, were Roman
Catholics, and Roman Catholics of
a peculiarly devout and
enthusiastic kind. The Protestant Establishment was
an alien Church, and could never be anything else; a
monument of conquest which it had been unwise to
set up. It presented itself to Mr. Gladstone as the
very core and pillar of disaffection, and it was very
easy to make out a strong case for its abolition. In
March 1868 he brought forward three resolutions,
declaring that it was the opinion of the House of
Commons that the Established Church of Ireland
should cease to exist, and the first division showed a
majority of sixty-one in favour of the project and
against the Government. In consequence of this
Disraeli advised the Queen to dissolve Parliament,
which was done in July. Writs were made returnable
in November, and the interval was spent in such
canvassing and platform work as the country had
never experienced before. Mr. Gladstone was beaten in Lancashire, Mr. W. H. Smith ousted
Mr. Mill from Westminster, and Mr. Roebuck lost his seat at Sheffield; nevertheless, the
general result of the polls was an immense gain to the Liberals, showing a majority for
them of 120 in the New Parliament. Mr. Gladstone, having found a seat at Greenwich, set
to work to obey the Queen’s bidding in forming a Ministry. The most notable accession to
the Cabinet was that of Mr. Bright, who became Secretary of State for India, thus marking
an epoch in Parliamentary history by the formal recognition of the extreme Radicals as a
party in the State. The great business of the session of 1869 was, of course, the Bill to
disestablish and disendow the Irish Church. No Irish question can be touched without
releasing the springs of oratory of a quality beside which the most impassioned appeals of
average English or Scottish speakers seem tame and halting. In the Commons the fight
was a foregone conclusion; but the Irish Church was an exceedingly wealthy corporation,
and the disposal of its possessions, to the value of sixteen millions sterling, afforded
matter for long and complicated debates in Committee. The Lords could not be persuaded
even to delay the Act on which the country and the House of Commons had spoken with
so much decision. The Bill passed its second reading by a majority of thirty-three, and
received the Royal Assent on July 26, 1869. Lord Derby had made his last speech on the
second reading of this measure, which he resisted with much of his ancient vigour and all
his splendid eloquence. He died in October of the same year, and, in the opinion of most
men qualified to form one, Parliament lost in him its most polished orator.
The Irish people at first showed few signs of gratitude for the disestablishment of
their State Church. The Fenians were giving fresh signs of activity, agrarian crime was of
frightful frequency during the winter of 1869–70, and the virulence of the anti-British
press became day by day more intense. Troops were poured into the country to repress
disturbance, and Mr. Gladstone set about preparing fresh measures of conciliation. The
Irish land system, theoretically almost identical in general principles to that of Great
Britain, not only differed from it in important details, but had come to be worked on

89. From a Photograph]
[by Annan &
Sons, Glasgow.
DAVID LIVINGSTONE,
1813–1873.
African Missionary
and Explorer. Born at
Blantyre, near Glasgow,
and in his youth worked
in cotton-mills in that
town. Sent to Africa by
the London Missionary
Society in 1838, he
thenceforth spent his life
in exploring and
evangelizing that
continent. In 1865 and
1870 expeditions were
sent in search of him. He
died at Ilala. His body
was brought to England,
and buried in
Westminster Abbey.
Liberal Triumph. Mr. Gladstone’s
Cabinet.
Death of Lord
Derby.
J. Ballantyne, R.S.A.] [In the National Portrait Gallery.
SIR EDWIN LANDSEER, R.A., 1802–1873.
This distinguished animal painter was born in
London. He was knighted in 1850, and in 1865
was offered and declined the office of President of
the Royal Academy. The picture represents him in
the studio of Baron Marochetti, at work on one of
the lions for the Nelson column. These were cast
in bronze, and placed in position in January 1867.
Irish Land
Legislation.
W. H. Mason.] [From a Print at the Oval.
wholly
different
lines from
those pursued by English
and Scottish landlords.
In
Great
Britain
the tendency had been
to throw small
unprofitable holdings
into substantial farms
which should be worth
the efforts of energetic
men of means to
cultivate. The landlord,
as a rule, equipped the
farm with suitable
buildings and fences,
and frequently lived on
his estates during most
of the year. In Ireland,
with few exceptions, buildings and improvements of every sort
were executed by the tenant, who was allowed to subdivide his
holding into mere patches of land, with a hovel run up at the
expense of the occupant. The peasantry were bound to their
holdings by the capital they had sunk in them; they could not in
every season wring the rent out of the land; huge masses of
arrears accumulated, often ending in eviction, which meant
practical confiscation of such permanent improvements as had
been effected. All the evil effects and bitter feelings arising out of this decrepid mode of
tenure were intensified by the ever-increasing tendency of landowners to absenteeism,
and by the prevailing difference in the religion of proprietors and peasantry.
In Ulster, indeed, the conditions
were different. Not only was there a
large Protestant element in the
farming and labouring class, but the
custom of tenant-right had grown up,
protecting the tenant against
disturbance as long as he paid his
rent, securing his right to
compensation on leaving for
improvements executed by himself,
and, most important of all, giving him
a saleable property in the goodwill of
the tenancy. The Ulster tenantry, as a

90. CRICKET IN THE EARLY YEARS OF THE REIGN.
Sussex v. Kent, at Brighton, 1842.
J. Leech.] [From “Punch.”
FASHIONS IN 1864.
The safest way to take a
lady down!
National
Education.
Army Purchase.
rule, were prosperous. Mr. Gladstone
refused to see in their prosperity only
the result of their greater industry and
capacity for business: he set it down to the system of dual ownership involved in the
recognition of tenant-right, and this system he resolved to apply to every part of Ireland
by creating a statutory partnership between landlord and tenant. It is hardly possible to
conceive a reform more vital than that initiated by this measure in the social fabric of
Ireland; for, except in the north-east of Ulster, agriculture forms the sole important
industry of that country. Yet the Conservative Opposition, led by Mr. Disraeli, made no
attempt to resist it; the case for legislation was too clamant.
Far-reaching as the Irish Land Bill has proved in its effects, it
was hardly of greater moment than a measure introduced two
days later by Mr. W. E. Forster, establishing a scheme of
elementary education. The Government had
been not more than two years in office, and
had amply fulfilled the first part of an ambitious
programme by passing three measures of extraordinary
importance, dealing with the Irish Church, Irish land tenure, and
national education; yet the tide of popular favour which had
carried them into power began to show unmistakeable signs of
ebbing. The legislation of 1871, actual and proposed, served to
add to the number of malcontents. The first
step taken was against the system of purchase
in the army. It was the recognised practice in all except a few
special corps in the British army for an officer to purchase his first
commission, as well as every subsequent step in regimental promotion. There was a
regulation scale of prices, but there was also an extra regulation payment, winked at by
the authorities. An officer’s commission thus became a valuable property to him, which he
could dispose of on leaving the service. It was a system which few people could defend
successfully in theory, but it was one that had worked well in practice; and the project to
sweep it away created a vigorous opposition. But what makes the Parliamentary fight over
army purchase of moment in history is the means by which Mr. Gladstone carried his
purpose in the teeth of the House of Lords. The abolition of purchase had been part only
of a sweeping measure of army re-organisation brought in by Mr. Cardwell. In order to
save part of the Bill, the Government threw overboard every section of it except the
purchase clauses. The Lords, desiring to defeat what was left of the original Bill, declared
they would not accept the purchase clauses until the whole scheme of army reform was
before them. A sigh of relief escaped from military men; the system endeared to them by
custom and association had been saved by the action of the Upper House. But they had to
learn how resolute and adroit was he with whom they had to reckon. Mr. Gladstone had a
theatrical surprise in store for everyone. He gave the go-by to Parliament by announcing
that, whereas army purchase had been created by Royal warrant, it could be rendered
illegal by the same means; and, therefore, he had advised the Queen to cancel the old
warrant and issue a new one. It was a complete victory over the House of Lords; they
were forced to pass the Bill so obnoxious to them, otherwise the officers of the army

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