Teaching Utility Applications of Power Electronics in a First Course on Power Systems.ppt

teaching utility applications of power electronics

1. Ned Mohan, Amit Jain, Philip Jose
University of Minnesota
and
Raja Ayyanar
Arizona State University
Teaching Utility Applications of
Power Electronics in a First
Course on Power Systems

2. 2
Outline
Importance of teaching power electronics in a
power systems course
Description of proposed approach consisting of
four segments
Functional aspects of power electronics
Power device capabilities and Power Electronic
Structures
Role of power electronics in utility applications
Details of the power electronics structures

3. 3
Control Center
Micro-Turbine
Hospital
Commercial
Building
Fuel Cell
Smart House
Performance
Building
Combined Heat and Power
Plant (CHP)
Factory
Commercial Building
House
Apartment Building
Wind Power Plants
Village
Commercial
Building
Central Power
Station
Solar Power Plants
CHP House
Importance
Increasing applications of Power Electronic
Equipment in Power Systems
Availability of high power
semiconductor devices
Decentralized renewable
energy generation sources
Increased power transfer
with existing transmission
system
Effective control of power
flow needed in a
deregulated environment
Norms for Power quality
Future Power System

4. 4
Approach
Top Down approach consisting of four segments
Function of power electronics as an interface, and the
listing of utility applications requiring power electronics
interface
(1 lecture)
Power device capabilities and the resulting structures of
power electronic interfaces to exploit them (1 lecture)
Importance and the role of power electronic interfaces in
various applications (2 lectures)
Discussion of power electronics interface in appropriate
detail (3 lectures)

5. 5
Segment 1: Function of Power
Electronics in Utility Applications
Enabling technology providing interface between
two (ac/dc) electrical systems
E.g.
Interconnection of two asynchronous ac systems
dc to ac conversion is required to connect fuel cells or
photovoltaics to the utility grid
Converter
Controller
Source Load

6. 6
Segment 1: Listing of Power Electronic
Applications
Distributed generation (DG)
Renewable resources (wind and photovoltaic)
Fuel cells and micro-turbines
Storage: batteries, super-conducting magnetic energy
storage, flywheels
Power electronics loads: Adjustable speed drives
Power quality solutions
Dual feeders
Uninterruptible power supplies
Dynamic voltage restorers
Transmission and distribution (T&D)
High voltage dc (HVDC) and medium voltage dc
Flexible AC Transmission Systems (FACTS): Shunt and Series
compensation, and the unified power flow controller

7. 7
Segment 2: Power Device Capabilities &
Resulting Power Electronic Structures
Power Semiconductor Devices and their Capabilities
Polarity of voltage blocked and direction of current
conduction
Switching speeds and power ratings
IGBT MOSFET
Thyristor IGCT
10
1
10
2
10
3
10
4
10
2
10
4
10
6
10
8
T
h
y
r
i
s
t
o
r
IGBT
MOSFET
P
o
w
e
r
(
V
A
)
Switching Frequency (Hz)
IGCT

8. 8
Segment 2: Structure of Power
Electronic Systems
Voltage-Link Systems
Transistors and diodes that
can block voltage of only
one polarity
Current-Link Systems
higher power bipolar voltage-
blocking capabilities of thyristors
Solid State Switches
bidirectional voltage blocking
and current conduction
AC1 AC2
AC1 AC2

9. 9
Segment 3: Role of Power Electronics in
Important Utility Applications
Distributed Generation (DG) Applications
Power electronic interface depends on the source
characteristics
AC
DC
DC
AC
Wound rotor
Induction Generator
Generator-side
Converter
Grid-side
Converter
Wind
Turbine
Isolated
DC-DC
Converter
PWM
Converter
Max. Power-
point Tracker
Utility
1f
Wind Power Generation with
Doubly Fed Induction Motors
Photo-voltaics Interface

10. 10
Segment 3: Role of Power Electronics in
Important Utility Applications
Power Electronic Loads: Adjustable Speed Drives
Controller
Motor
Utility
Rectifier
Switch-mode
Converter

11. 11
Segment 3: Role of Power Electronics in
Important Utility Applications
Power Quality Solutions for
voltage distortion
unbalances
voltage sags and swells
power outages
Load
Feeder 1
Feeder 2
Dual Feeders
Power Electronic
Interface
Load
Dynamic Voltage Restorers (DVR)
Uninterruptible Power Supplies
Rectifier Inverter Filter
Critical
Load
Energy
Storage

12. 12
Segment 3: Role of Power Electronics in
Important Utility Applications
Transmission and Distribution: DC Transmission
most flexible solution for connection of two ac systems
AC1 AC2
HVDC
AC1 AC2
MVDC

13. 13
Segment 3: Role of Power Electronics in
Important Utility Applications
Transmission and Distribution: Flexible AC
Transmission Systems (FACTS)
1 2
sin
E E
P
X

1
E
2E
3E
+-
3
E
1
E
2
E
Shunt
converter
Series
converter
I
Shunt and Series Compensation
Series Compensation
Shunt Compensation
Utility
STATCOM
jX

14. 14
Segment 4: Discussion of Power
Electronics Interface
Fundamental concepts for understanding the
operation of the power electronic structures
voltage-link systems
current link systems
solid state switches

15. 15
Voltage-Link Systems
Unifying approach: Power-Pole Building Block
building block of all
voltage-link systems
AC1 AC2
dA
i
Av
A
i
d
V
controlv
1or 0
Aq
A sd T
+
-
+
-
PWM
Voltage
port
Current
port

16. 16
Voltage-Link Systems
Power conversion using Pulse Width Modulation
(PWM)
Power reversal with reversal of current direction
Averaged conversion
dA
i
Av
A
i
d
V
controlv
1or 0
A
q
A s
d T
+
-
+
-
PWM
Voltage
port
Current
port
Av
t
dV
A
v
As
dT
sT
on
A d A d
s
T
v V d V
T
 

17. 17
Voltage-Link Systems
Averaged Representation of Power Pole
Average quantities are of main interest
dA
i
A
v
Ai
dV
controlv
A s
d T
+
-
+
-
PWM
1:
A
d
dA
i
Av
A
i
d
V
controlv
1or 0
Aq
A s
d T
+
-
+
-
PWM
Voltag
e
port
Current
port
( ) ( )
A A d
v t d t V 
( ) ( ) ( )
dA A A
i t d t i t 

18. 18
Voltage-Link Systems
Synthesis of AC voltages
voltage to be synthesized
duty ratio needed
dc side current
Ai
t0


v
dV
dV
2
0 t
Av
I


( ) sin
2
d
AN
V
v t V t  

1
sin
2
Ad d t  


 
 
1
( ) sin ( )
2
1
ˆsin sin( )
2
1
ˆcos sin( ) cos(2 )
2
dA
ai t d t i t
d t I t
I d t d t

  
    
 
  
 
 
 
   
 
 
      

19. 19
Voltage-Link Systems
Implementation of bi-positional switch
A
i
d
V
+
-
A
q
A
q
1
A A
q q 
dAi
Av
A
i
d
V
1 or 0
A
q
A s
d T
+
-
+
-

20. 20
Current-Link Systems
Exclusively thyristor based
One of (T
1
, T
2
, T
3
) and (T
2
, T
4
, T
6
)
conduct at a time
Average dc voltage controlled
by ‘firing angle’
Power flow reversed by reversing
voltage polarity
AC1 AC2
3 2 3
cos
d LL c dV V L I  
 
 
a
i
b
i
c
i
d
v
+
-
d
I
1
T
3
T
5
T
4
T
6
T
2
T
c
L
bL
a
L

21. 21
Solid State Switch
Can conduct current in both directions
Turn-on or off in an ac circuit in one-half of a line-
frequency cycle

22. 22
Conclusion
Teaching utility applications of power electronics in a
power systems course is very important
A top down approach, starting with functional
aspects and going to implementation details is
suggested
Topics outlined in the four segment proposed
structure will introduce students to future practices
and technologies in power engineering
The proposed structure may be adapted based on
individual preferences