Basic Electrical of Power plant , SLD , Excitation

Basics Electrical for Beginners of Power Plant

1. 1
Presented By:
Mr. MANOJ KUMAR MAHARANA
HOD [ Dept. Of Electrical ]
FEEDBACK POWER O&M PVT. Ltd
Basic of Power Plant
Electrical system
/ SLD / SOP / SMP
Dt. 05/08/2015

2. 2
Target Audience :
Engineers & Technicians

3. 3
Basic of Power Plant Electrical
•A
 
Power Plant Electrical mainly understood by Generation,
Transmission & Distribution system.
•Transform
 voltage from high to low, or the reverse, or perform any
of several other important functions.
•Maximum Equipment generally have Breakers, Isolators ,
CTs ,PTs , Bus bars, protection and control equipments,
transformers ,grounding wires and switches, disconnects and
metering devices, etc.

4. 4
•Single Line Diagram
•Generator
Excitatation system, AVR, Synchronization
•Motor
•Transformer
•Electrostatic Precipitator
•Batteries
•Earthing
•Measuring & Protection Instruments
•Standard Operating Procedure & Maintenance
Overview

6. 6

7. 7
The functions of Various panels are as below:
L.A, S.C, C.T, P.T Panel:
In this panel the L.A as well as S.C are used for the protection of the system from the
voltage
 surge due to lightning as well as due to the transient situation and the C.T as well as P.T
are being used for the protection, metering, synchronising and A.V.R purpose.
Metering and relay panel:
This panel is being used for the metering of each and every components used in the system,
through which the proper controlling can be easily done. The output of all the transducers and
the sensors as well as the C.T and the P.T are connected to the panel for the metering and relay
purpose.
 
Synchronising panel:
This panel is used when the synchronisation of the generator is to be done. It has various modes
of the synchronisation of the generator stated as Auto, Manual and Dead bus. The output of the
generator which is to be synchronised and the running bus are being send to the panel for the
synchronisation process.

8. 8
 
A.V.R Panel: 
(Automatic Voltage Regulator)
This panel is being used for the controlling the reactive power, which is the input of the
generator so that a regulated voltage can be produced through it with the change in loads.
P.C.C panel:
 
(Power control centre)
The Auxiliary transformer feeds the power to the P.C.C panel and further the panel provides
power to the M.C.C panel for the controlling of various systems in the power station.
M.C.C Panel: (Motor Control Centre)
This panel is being used to control the various motors in the plant from the single panel .This
panel is used for easy as well as the safe operation of the various motor used in the plant.
T.S.P Panel:
 
(Turbine supervisory panel)
This panel is being used for the control of the turbine. The vibration as well as speed is being
regulated through it. The various comparator circuits are being used to it.
D.C.S system: 
(Distributed control system)
It is used for visual monitoring of the total power plant and it shows whether all the apparatus
are in healthy situation or not and we can check out all the parameters of the total system
through a single D.C.S system.
 
The functions of various panels are as below:

10. Alternator:
An Alternator is an equipment which converts
Mechanical Energy into Electrical Energy.

11. •STATOR
•ROTOR
•EXCITER
•SLIP RINGS
•BRUSHES
•BEARINGS
•COOLING SYSTEM

12. •To supply the field winding of the generator with dc current
and control it.
•This keeps the terminal voltage constant
•Ensures proper reactive power sharing
•Improves stability
Why Excitation System?
•The amount of excitation required to maintain the generator output
voltage constant is dependant on the load on the generator. As the
load on the generator increases, the rotor excitation current must
increase to maintain a constant voltage on the generator output.

13. Excitation System

14. Automatic Voltage Regulator
•Automatic Voltage Regulator (AVR) set to regulate
generator terminal voltage in the voltage control mode
unless specifically directed to operate in manual
mode .
•AVR control the strength of the electromagnetic field
in the generator
•AVR compare the generator bus voltage from a PT to a
set point in the Automatic voltage regulator . The
difference between the two is used to control the
amount of excitation current that is being supplied to
excite the field of the generator.

15. AC - DC
CONVERTER
+
-
TO EXCITERPOWERING
REFERENCE
PROCESSING
FEEDBACK
PROCESSING
CONTROLLER
FIRING PULSE
GENERATOR
Reference Feedback
Aux. power
Aux. power
Automatic Voltage Regulator

16. •There are two identical AVRs present
•The AVR will not come into line unless the turbine
reaches 85% of full speed
•One of the AVR will be on line and the other one will
remain as standby.
•If the main AVR fails , then the stand by AVR will
automatically come onto line
•A manual excitation control provision also exists
Automatic Voltage Regulator

17. Control feedback

19. TURBINE REACHES FULL SPEED
CLOSE THE FIELD BREAKER
BUILD UP VOLTAGE TO 6 KV
SYNCHRONISATION
INCREASE THE LOAD
ISLAND OPERATION
PARALLEL OPERATION

Start-Up Sequence

20. GRID
CIRCUIT
BREAKER
GEN
ARE THE VOLTAGES SAME?
ARE THE PHASE SEQUENCES SAME? ARE THE FREQUENCIES SAME? YES
What is Synchronization ?

21. •Voltage and Frequency are fixed by GRID
•Governor set point decides the Real Power
•Field current decides the Reactive power
TO SUMMARISE:

23. 23
Basic Formulas

24. 24
Motor Connections

25. Manual DOL starter
L
2
L
1

M
3~
M
3~

26. Contactor controlled DOL starter
L
2
L
1 L
3
K1.2
K1.3
K1.4
K1.1
1
1
2
3
4
5
TOL
TOL
Stop
C/B

Start


K1/4K1/4
M
3~

27. L
2L
1 L
3
K1.2
K4.1
K2.1
K1.1
TOL
TOL
C/B


K1/3K1/3
M
3~
K1.3
K3.1

K2/4K2/4 K4/3

K3/2
Star-Delta starter
K3/2 K4/3
K2.1 K2.4
K2.3
K3.1
K4.2K4.3
Start Delta Timer Line
S1
S2
A1
M
3~
B1
C1
A2
B2
C2

28. 28
Comparison B/W Star Delta Connection

29. 29
What are the advantages of using Star
Delta starting?
•The most significant advantage is the
reduction in starting current. The starting
•current will to a large extent determine the size
of the cables used, the size of the circuit
breakers,
•the size of the fuses, as well as the
transformers.

31. Transformer is static AC machine which transfers the electric power energy
from one electrical circuit to another electrical circuit with same frequency.
It work on mutual induction(Electro magnetic induction) principle.
Transformers

32. 09/12/2024 360 Chapter 5 Transformers 32
Transformers
Transformer
Connection
Primary and Secondary Voltage
Phase Relation
Phase
Shift*
Windings Placed on the
Same Leg
Wye-Wye V
AN
is in phase with V
an
Zero A and a
Wye-Delta V
AN
is in phase with V
ab
30° A and ab
Delta-Wye V
AB
is in phase with V
an
–30° AB and a
Delta-Delta V
AB
is in phase with V
ab
Zero AB and ab
* Note: Phase shift lead between line-to-line voltages, V
AB
and V
ab
, and line-to-neutral
voltages, V
AN
and V
an
, and line currents, I
A
and I
a
.
Three-phase Transformer Relations
Transformers

34. Boiler Circuit with Precipitator

35. ELECTROSTATIC PRECIPITATOR WORKING PRINCIPLE
•The precipitation process involves 4 main functions
•Corona generation
•Particle charging
•Particle collection
•Removal of particles
ELECTROSTATIC PRECIPITATOR PRINCIPLE

36. Corona Generation

37. ESP - PARTICLE CHARGING
•The -ve charges of ions and free electrons travel towards +ve electrode and the
+ve charges of ions travel towards -ve electrodes.
•When -ve ions travel towards +ve electrodes, the -ve charges get attached to the
dust particles and thus the dust particles are electrically charged,
Particle Charging

38. 38
Particle Charging

39. 39
Particle Collection

40. Removal Of Particle

42. DC System
Batteries
Battery Chargers
DCDB

43. - Very Reliable DC power to Switch gear controls & protection,
Emergency lighting and to support critical process where an in
process power failure could have disastrous results.
-As much as redundancy as possible into a stand by power system
-AH capacity : is defined as the capacity of the batteries to
discharge for a specified time duration at its rated current until
the prescribed end voltage is reached
-220/110/24 volts DC : Where normal DC load is high due to
requirement of large electrical / instrument installation.
DC System

44. SBPL 44
 Battery Maintenance
•Keep the Battery room well Ventilated
•Keep the battery and its surrounding dry and clean
•Check and keep the electrical connections always
tight
•If any connection tends to get heated up, it denotes
a loose connection.
•Should there be any corrosion of the racks, clean
the affected parts thoroughly and protect them from
corrosion by coating with acid proof paint.

46. In electrical engineering, the term ground or earth has the
following meanings
A common return path in electrical circuits
an electrical connection to earth, using metal rod (the earth
electrode) or stake driven into the earth.
grounding is the wire that carries currents away under fault
conditions
it is the zero voltage reference level for the equipment or system.
EARTHING:- Earth-ing

47. Personnel safety.
to control the voltage to earth or ground within safe and predictable limits
To safely conduct the earth fault current of sufficient magnitude for fast
operation of the circuit protection devices
to limit the transient over voltage caused by re-striking ground faults, well
within basic insulation level of equipment.
to prevent electric fire and damage to equipment by fast and selective isolation
of ground faults.
SYSTEM AND EQUIPMENT GROUNDING :-
 System grounding: The connection of some part of electrical power supply
system(usually the middle wire or neutral point of transformer or generator winding)
is intentionally grounded either solidly or through an impendence.
 Equipment grounding: The grounding of all the metallic equipment and enclosure
frames, through bonding of all component parts and their connection to ground.
Objective Of Earthing

49. Instruments Transformers

 These are used to protect apparatus from high Voltage and permit
use of
reasonable level and carrying current capacity in relay & meter.
 General rating CT is 5amps and 1amps and PT110Volts 50cycles on
secondary
side.
1.Current Transformer (CT)
2. Potential Transformer (PT)

50.  The CT are used to step down the current at a circuit to
lower value.
 The CT steps down the incoming 800/400amps to 1 or 5
amps.
 These are connected in series to the equipment in the
Layout.
 The Main two function of the CT are –
1. Measurement
2. Protection
Current Transformers

51. TRANSFORMER CT’s SECONDARY CONNECTIONS
Line CT Secondary Connection

52.  The PT are used to step down the voltage of a circuit to
a low value that can be effectively and safely used for
operation and instruments.
 These are connected in parallel to the System.
 The Main two function of the PT are –
1. Measurement
2. Protection
Potential Transformers

53. Based on Characteristic
1. Definite time Relays
2. Inverse time Relays with
definite minimum time (1 DMT)
3. Instantaneous Relays
4. IDMT with inst.
5. Stepped Characteristic
6. Programme Switches
7. Voltage restraint overcurrent
relay
Based on of logic
1. Differential
2. Unbalance
3. Neutral Displacement
4. Directional
5. Restricted Earth Fault
6. Over Fluxing
7. Distance Schemes
8. Bus bar Protection
9. Reverse Power Relays
10.Loss of excitation
11.Negative Phase
Sequence Relays etc.
1. Thermal
(a) OT Trip
(b) WT Trip
(C) Bearing Temp Trip etc.
2. Float Type
(a) Buchholz
(b) OSR
(c) PRV
(d) Water level Controls etc.
3. Pressure Switches
4. Mechanical Interlocks
5. Pole discrepancy Relay
Based on actuating
parameter
1.Current Relays
2. Voltage Relays
3. Frequency Relays
4. Power Relays etc.
Relay



MechanicalElectro Magnetic Static/Numerical
Protective Relays

54. What are Relays?
•Relays are electrical switches that
open or close another circuit under
certain conditions.
What is a Relays ?

55. Circuit breakers are used for automatic isolation of fault in very short duration
after receiving the command from relay. If the fault is not cleared in time it may
lead to disturbance in the system.
Circuit Breakers

56. Protection System
•A series of devices whose main purpose is to protect
persons and primary electric power equipment from
the effects of faults.
•There is no ‘fault free’ system.
•It is neither practical nor economical to build a ‘fault
free’ system.
•Electrical system shall tolerate certain degree of faults.
•Usually faults are caused by breakdown of insulation
due to various reasons: Short Circuit, High Voltage,
system aging, lighting, etc.

57. How Do Relays Detect Faults?
•When a fault takes place, the current, voltage, frequency,
and other electrical variables behave in a peculiar way.
For example:
–Current suddenly increases
–Voltage suddenly decreases
•Relays can measure the currents and the voltages and
detect that there is an overcurrent, or an undervoltage, or
a combination of both
•Many other detection principles determine the design of
protective relays

58. Protection System Elements
•Protective relays
•Circuit breakers
•Current and voltage transducers
•Communications channels
•DC supply system
•Control cables

59. Three-Phase Diagram of the Protection scheme
CTs
VTs
Relay
CB
Control
Protected
Equipment

60. R
Y
B
Winding
Winding
Winding
NGR
RELAY
O/C OCCURS
I > 540 A
Relay operates in ‘ t ‘ sec
CTS
Over Current Relay
Breaker

62. 62

63. 63

64. 64

65. 65

66. Thanks To All
Prepared By:
Mr. MANOJ KUMAR MAHARANA
Sr. Engineer [ Dept. of Electrical ]
Feedback Power O&M Pvt Ltd