SYNCHRONOUS GENERATOR TURBINE GOVERNOR EXCITATION TRANSFORMER 2 EXCITATION SYSTEM GENERATOR BREAKER 1 1 SYNCHRONIZING 2 PROTECTION STATIC STARTER CONTROL SYSTEMS AC & DC AUXILIARY SYSTEMS STEP UP TRANSFORMER HV- BREAKER HV SYSTEM CONTROL ROOM PT’s & CT’s AUX. TRANSF. STAR POINT CUBICLE LV SWITCHGEAR The power station
it is usual for presentation for both electrical and electronics student who got training in NTPC faridabad
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
• Exciter response limited by the exciter machine time constant (>200ms)
• Field discharge with natural time constant
• Supply from PMG possible providing supporting of short circuit currents
• Relative large size of exciter machine for low speed generators
• No sliprings (less maintenance and dust)
Neutral terminal
• Grounding transformer used to reduce fault currents.
• The 100% stator earth fault detection is also done through this transformer
Starting system
• SFC manufacturer-AEG Germany
• Rating-2.9 MW
• Modes of operation:washing at 600 rpm
• Boiler purging at 900 rpm
• Unit black start at link circuit current 2.7 MW 1360 RPM
• Power operation at max dragging 2.9 Mw 2100 RPM
Transformers
• Generator transformer
• Unit auxiliary transformer
• Excitation Transformer
• MV/LV Transformers
• Lighting Transformers
• Three Phase, 153.5 MVA, BHEL make.
• Delta Star, neutral solidly grounded.
• 10.5/230 kV.• Cooling-ONAN/ONAF/
OFAF • Off circuit Tap changer at
five positions• Oil quantity:-39715 liters
Generator transformer UAT
• Rating 25 MVA 10.5/6.9 kV
• Cooling: ONAN/ONAF
• Quantity of oil-13095 liters
• On load tap changer at 12 positions
Busduct and UAT
Gen. Transformer
System
• There are two Unit Transformers connected thru GT, 10.5 KV Bus.
• These two Transformer make 2no. 6.6KV bus ( 11 &12 BBE) which in turn make another 2 bus thru Ties.(OCA- A&B)
• A total 4no 6.6KV bus exists which are interconnected thru Ties and Bus coupler.
• DG is also connected to OCA (A&B) bus thru 6.6KV Breakers.
6.6KV BUS SYSTEM
Changeover Schemes
Changeover Schemes are divided in Two Group: A. With Paralleling B. Without Paralleling Here there are Four Types of Schemes under these
Categories:• MANUAL Changeover • FAST Changeover• SLOW Changeover• BLACKOUT Condition
Manual Changeover Scheme
Features:
• It is a planned changeover.• Thru Operator Intervention.• No Interruption in Voltages.• Thru Synchronizing Relay
Manual Changeover Scheme
Scope:
1. Bus coupler at OCA
2. UAT Incomer ( BBE01&2)
3. DG Breaker 1&2
4.Tie Breaker at OCA( Tie1 &2)
Manual Changeover Scheme
Example :
U1-B/C-U2 Changeover:
--Proven scheme
--Either of Breaker can be closed thru ECB.
--Choice of Breaker tripping is done thru Trip selection switch.
Fast Changeover Scheme
Feature:• This is only for OCA Bus coupler.• This changeover occurs when Voltage sink is
likely to occur. • OCA Bus coupler will close in Auto without any
time delay. No manual Intervention possible.• This changeover will take place in less than
200millisecond, hence chances of supply interruption is very less.
Slow Changeover Scheme
Features:
• This is a backup of Fast changeover.
• Bus coupler will close in auto after certain Time delay and fulfillment of certain condition
• Chances of unit survival depends on situation
Black Out Condition
Normally blackout condition means:
• 1. All GCB and HVCB open.
• 2. Both Unit Incomer Breakers Open
• 3. No Auxiliary Power at station.
At this moment our attempt to restore the Auxiliary power as soon as possible.
Black Out Condition
Under this Condition:• DG set will take start in Auto• All Aux. Feeders at OCA Bus will Trip• Both DG Breakers will closed in Auto.• Priority Transformer feeders will close in Auto,
also their LT Incomers(except PCC) • Tie feeders at OCA and PCC will not Trip• This all will be done thru Logics As:
Black Out Condition Contd.
If due to any reason DG fail to start or DG Breaker does not close in Auto :
• Start DG Manually• Close the DG Breakers one by one• Close the Priority feeders one by one.
Black Out Condition --Normalisation
2. Thru GT1 and GT2 Transformer :• Back charge the transformer and close the U1 and
U2 breaker thru manual Changeover. D1 and D2 will trip respectively in auto.
3. Thru Unit Start Up.• Start Gas Turbine1/2 in Black Start mode. U1/U2
Breaker will close and D1/D2 will Trip in Auto.
Black Out Condition
Others:• During D1/D2 close condition—• Only Priority feeders can be closed- i.e ODA A
&B Breaker( Only emergency section, ODC I/c-A&B, and Common transformer breaker.)
• Other than Priority 6.6 KV fdr , no 6.6 KV fdr can be closed
• 415V,ODA-B/C D&E , CW &Chlorination fdr., OSF MCC, Nox and Misc MCC can not be closed.
Supply to Switchyard
Switchyard
EHV Control and Switchgear
• Circuit Breaker
• Isolator
• Current Transformer
• Capacitive Voltage Transformer
• Lightning Arrestor
• PLCC equipment
• Bus Switching Schemes
• Disturbance recorder
• Event logger
• Remote telemetering units
Line diagram
Bus Switching Schemes
3 Generators
Bus Coupler
Transfer Bay
4 Transmission lines
Transfer Bus
Main Bus-1
Main Bus-2
Double main and Transfer bus scheme
PLCC System
Tx
Rx
Tx
Rx
CVT
Wave trapSubstation A Substation B
Electrical Protections
• Generator and transformer protections• 6.6 kV Protections
– Station transformer protections – Motor protections– Transformer protections
• 220 kV Protections– Line protections– Bus bar protection– Breaker failure protection
VT Panel Protection Panel Terminal Box
Protection Panel
Numerical Relays
Backside of relays
Tripping Matrix
Tripping Relay
Generator Protection:Protection Functions (1)
Generator differentialOver current protectionVoltage dependent backupStator earth faultNeutral displacementSensitive directional E/F100% Stator E/FUnder & over voltageUnder & over frequency
6.6 kV Protections• Station transformer protections
– Three phase Over current protection.– Earth fault protection.– Restricted earth fault protection.
• Motor protection– IDMT over current protection– Earth fault protection
• Transformer protection– IDMT over current protection– Earth fault protection
EHV Protections
• Line protections
• Transformer protections
• Generator Protections
• Bus bar protection
• Breaker failure protection
Line protections
• Main I Distance protection (21-1)
• Main II Distance protection (21-2)
• Breaker failure relay.
• Trip circuit supervision relay
• Trip coil supervision relay.
• Fault locator
• Disturbance recorder
Distance Protection
Zone 1: 80%, 0mS
Zone 2: 120%,300mS
Zone 3: 200%,1000mS
A B
220 kV Transformer protections
• Transformer Differential protection.(87)• Three phase over current protection. (51)• Earth fault relay (Phase current balance)• Breaker failure relay.• Bucholz relay• Winding temperature relay• Oil temperature relay• Pressure relief device
DC SYSTEM
DC Systems
• 220 Volts DC Gas Turbine batteries
• 220 and 24 Volts Station batteries
• 432 Volts UPS batteries
• 220 Volts Emergency Lighting batteries
• 48 V Switchyard Battery systems
415 Volts System
• GT MCCs– All the LT auxiliaries of Gas turbine including: