switch yard
TRANSCRIPT
220KV SWITCHYARD AT
UNCHAHAR
PRESENTED BY:
NITISH KUMAR GUPTA
ET-2011
OPERATION-GROUP C
Substations
• HVAC : 220, 400, 765 KV• HVDC: +/- 140, 200, 400, 500, 800 KV
• Air Insulated Substation• Gas Insulted Substation
• Indoor • outdoor
COMPONENTS OF 220KV SWITCHYARD
• Bus-Bar.• Circuit Breakers (C.B.).• Current Transformers
(C.T.).• Potential Transformers
(P.T.).• Capacitive Voltage
Transformers (C.V.T. ).• Lightning Arrester (L.A.).• Isolators.• Earthing Switch.• Line traps
Layout & Schematic Diagrams
C.T.P.T.
L.A.
C.B.
BUSBAR
ISOLATOR
EARTHING SWITCH
CVTCVT
Busbar arrangements
• Single busbar• Double busbar• double busbar with transfer bus• Mesh busbar• Double Breaker• 1-1/2 breaker
Single busbar
lines
coupler
Double Busbar
Double Main and Transfer Busbar (DMT)
Transfer Bus
Bus#1
Bus#2
1 1/2 Breaker scheme
SYSTEM ARRANGEMENT AT UNCHAHAR
BUS-3
BUS-4
Transfer BUS
G-3
GT-3
UAT-3BUAT-3A
GCB
LINE ISOLATOR
BUS SECTION BREAKER
BUS-1
BUS-2
BUS ISOLATORS
220 KV SWITCHYARD SCHEME ( GENERATOR )
15.75 KV
6.6 KV Unit Buses
220 KVEarth Switchs
13-52-A,B,C
89-13-3
250MVA, 15.75/237KV
16MVA, 15.75/6.9KV
89-13-289-13-1 89-13-4
BUS-3
BUS-4Transfer BUS
ST-3
LINE ISOLATOR
BUS SECTION BREAKER
BUS-1
BUS-2
BUS ISOLATORS
220 KV SWITCHYARD SCHEME ( STATION TRANSFORMER )
6.6 KV Station Buses
220 KV
14-52-A,B,C
89-14-3
89-14-189-14-2
SE-2SE-1
40 MVA, 22/6.9kV
89-14-4
BUS-3
BUS-4Transfer BUS
LINE ISOLATOR
BUS SECTION BREAKER
BUS-1
BUS-2
BUS ISOLATORS
220 KV SWITCHYARD SCHEME
( TRANSFER BUS COUPLER )
220 KV
TBC Breaker
89-17-3
89-17-289-17-4
89-17-1
17-52-A,B,C
BUS-3
BUS-4Transfer BUS
BUS SECTION BREAKER
BUS-1
BUS-2
220 KV SWITCHYARD SCHEME
( BUS COUPLER )
B/C BKR
23-52-A,B,C
BUS-3
BUS-4Transfer BUS
LINE ISOLATOR
BUS SECTION BREAKER
BUS-1
BUS-2
BUS ISOLATORS
220 KV SWITCHYARD SCHEME ( OUTGOING FEEDERS- KANPUR 1 )
Line Breaker
OUTGOING FEEDERS
19-52-A,B,C
89-19-1
89-19-3
89-19-289-19-4
POWER EVACUATION SCHEME AT UNCHAHAR
KANPU
R-4
KANPU
R-1
RB-3
FP-1
KANPU
R-3
KANPU
R-2
FP-2
RB-1
U#2 U#1U#3
MAIN BUS 3 AND 4 MAIN BUS 1 AND 2
RB-2
SECTIONALIZER ST-1
ST-2
ST-3
ST-4
U#5 U#4
Feeder Arrangement
S.No Feeder Type No of Feeders/Bays
1 Generator 05
2 Station Transformer 04
3 Outgoing Transmission Line 09
4 Bus-Section Breaker 01
5 Bus-Coupler Breaker 02
6 Transfer Bus-Coupler 02
EQUIPMENT DESCRIPTION
CIRCUIT BREAKERS
1. ALL THE THREE STAGES HAVE SINGLE PRESSURE, PUFFER TYPE SF6 CIRCUIT BREAKERS
2. OPERATING MECHANISMS OF BREAKER FOR THE THREE STAGES ARE DIFFERENT:
PNEUMATIC HYDRAULIC SPRING
DESCRIPTION OF VARIOUS C.Bs 1. PNEUMATICALLY OPERATED SF-6 C.B. BREAKER MAKE- CGL SF6 GAS P- 6KSC RATED VOLTAGE- 245kV RATED CURRENT- 3150 Amp S.C.C- 40kA (3 SEC.) S.C. BREAKING CURRENT- 40kA LIGHTING IMPULSE WITHSTAND V- 1050kV (p to p)
AIR PARAMETERS: NORMAL- 15KSC COMPRESSOR START- 14.5 KSC COMPRESSOR STOP- 15.5 KSC AIR PRESSURE LOW ALARM- 13.2 KSC AIR PRESSURE LOW LOCKOUT- 12.0 KSCSF6 PARAMETERS: NORMAL- 6.0 KSC ALARM- 5.5 KSC LOCKOUT- 5.0KSC
DESCRIPTION OF VARIOUS C.Bs
2. HYDRAULICALLY OPERATED SF-6 C.B. BREAKER MAKE- BHEL SF6 GAS P- 6.5KSC RATED VOLTAGE- 245kV RATED CURRENT- 2800 Amp S.C.C- 40kA (3 SEC.) LIGHTING IMPULSE WITHSTAND V- 1050kV (p to p)
NORMAL OIL PRESSURE- 313-325 bar ALARM- 273 bar LOCKOUT- 253 bar
SF6 PARAMETERS: NORMAL- 6.5 KSC ALARM- 5.7 KSC LOCKOUT- 5.5KSC
FILTER
PUMP
NRV
P.SW
P.SW
CYLINDER
MAIN VALVEY1(CLOSE)Y2/Y3(OPEN)
OIL N2
OIL TANK
SAFETYVALVE
PRESSURE RELIEFVALVE
Pr GAUGE
ACCUMULATOR
ELECTRO HYDRAULIC MECHANISMFOR 220 KV SF-6 BKR
DESCRIPTION OF VARIOUS C.Bs
3. SPRING OPERATED SF-6 C.B. BREAKER MAKE- ALSTOM RATED VOLTAGE- 245kV RATED CURRENT- 2500 Amp S.C.C- 40kA (3 SEC.) LIGHTING IMPULSE WITHSTAND V- 1050kV (p to p)
Isolators/Disconnectors
• USED FOR ISOLATING THE CIRCUIT PHYSICALLY• OPERATE AT NO LOAD• INTERLOCKED WITH BREAKERS AND EARTHSWITCHES• SHOULD WITHSTAND EXTREME WIND PRESSURES• MOTOR DRIVEN AND HAND DRIVEN• LOCAL AS WELL AS REMOTE OPERATION POSSIBLE• ISOLATES SECTIONS FOR MAINTENANCE
FEATURES OF EARTH SWITCHES
• USED TO GROUND SECTIONS REQUIRED FOR MAINTENANCE
• GROUND TRAPPED CHARGES & INDUCTION VOLTAGES
• INTERLOCKED WITH BREAKERS AND ISOLATORS• CAN BE OPERATED FROM LOCAL ONLY• MOTOR DRIVEN AS WELL AS HAND DRIVEN• SAFETY DEVICE
Current Transformer
• Function– To isolate Instrument from High voltage– Reduce High current into low current
• Dead Tank• Live Tank• Optical CT
CURRENT TRANSFORMER
• ITS VA RATING=30VA• SECONDARY CURRENT= 1Amp• IT HAS 5 SECONDARY CORES• CORE-1 BUS BAR MAIN ZONE• CORE-2 BUS BAR CHECK ZONE• CORE-3 METERING CORE• CORE-4 DIFFERENTIAL PROTECTION• CORE-5 DIRECTIONAL OR O/C PROTECTION
Voltage Transformer
• Function– Isolation from high voltage– Reduce high voltage into low voltage
• Electromagnetic• Capacitor voltage transformer
CAPACITIVE VOLTAGE TRANSFORMER
• SECONDARY VOLTAGES(110 VOLTS AC) FOR VOLTMETERS AND ENERGY METERS
• VOLTAGES FOR PROTECTIVE RELAYS• VOLTAGES FOR SYNCHRONIZING • DISTURBANCE RECORDERS AND EVENT LOGS• OVERFLUX RELAYS• PLCC
CVT Equivalent Circuit
Z 2
U 1
C1
C2 U 2
Lightning arrester
• Device connected between conductor and ground which protects power equipments from abnormal high voltages.
Sources of overvoltage
EXTERNAL:-– LIGHTENING – GEOMAGNETIC STORM.
INTERNAL – SWITCHING
• LINE/CAPACITOR SWITCHING.• INDUCTIVE CURRENT BREAKING
RELAYS
…Development of Relay TechnologyRelay Electromechanica
lStatic Numerical
Measuring Element
Magnets, coil, Induction disc, etc
Diodes, Transistor,Comparators, ICs, etc
Microprocessor based, DSPs etc
Measuring Mode
Electrical Quantities converted to mechanical forces, torque
Detectors, Comparison with Reference value in Analog Comparator
A/D Converters, Numerical Algorithms etc
Timer Mechanical clock works, dashpot
Static timers Counters
Indication Flags LEDs LEDs, LCD
FUNCTIONS PERFORMED BY NUMERICAL RELAY
PROTECTION
COMMUNICATION
CONTROL
CONDITIONMONITORING
FUNCTIONS PERFORMED BY NUMERICAL RELAY
AUTORECLOSING
• 80% OF FAULTS ARE OF TRANSIENT NATURE, SO JUST BY INTERRUPTION OF SUPPLY WE CAN REMOVE THEM
• AT EHV LEVELS ONLY ONE RECLOSURE IS ALLOWED TO AVOID THE POSSIBILITIES OF UNSTABLE LOAD SWING(AT DISTRIBUTION LEVELS 3 RECLOSURES ARE GIVEN BEFORE LOCKOUT, AS THERE THE MAIN COCERN IS CONTINUITY OF SUPPLY)
AUTO-RECLOSE RELAY
• THESE ARE LOCKOUT TYPE ELECTROMECHANICAL RELYS
• RECLOSE TIME- 20 Sec• ONCE LOCKOUT, WE HAVE TO RESET IT MANUALLY• AUTO-RECLOSE SELECTION SWITCH:1. SINGLE PHASE(NORMAL SELECTION)2. THREE PHASE
Power Line Carrier Communication
• Uses same Power wire for communication• Uses High frequency for communication• Voice signal and Protection signal are
modulated on carrier frequency
C=1/2ΠFC
30KHZ TO 500KHZ
IMPEDENCE 75 OHMS
WAVE TRAP2ΠFL
L
PLCC
POWER FREQ -50 KHZ
STATION BUS
LINE
BASIC ARRANGEMENT OF WAVE TRAP AND COUPLINGCAPACITOR
>500KHZ NOISE PICKUP<30KHZ-HARMONICLIGHTENING,CORONA
WAVE TRAP
1.RATED INDUCTANCE( 0.5/ 1.0mH)
2.RATED CURRENT
3.BAND WIDTH
4.COUPLING (PHASE TO PHASE)
SWITCHYARD AUXILIARY SYSTEMS
• AC SUPPLY FOR CONTROL ROOM• A RELIABLE 415V AC SUPPLY ( LT SWGR)• 220 V & 48 V DC SUPPLY( BATTERY & BATTERYCHARGER)• POWER & CONTROL CABLE• LIGHTING ( Yard lighting & indoor lighting of control room)• AIR CONDITIONING
AT UNCHAHAR WE HAVE 2* 1 MVA , 6.6KV/433V TRANSFORMERS WHICH PROVIDE AUX. AC SUPPLY FOR SWITCHYARD
PROCEDURES AND SYSTEM
TAKING A CIRCUIT OUT OF SERVICE
TAKING ISOLATION ON A FEEDER
1. OBTAIN SHUTDOWN APPROVAL CODE FROM NRLDC/CPCC/CLDS BASED ON WRITTEN MESSAGE FROM UCR END
2. INTIMATE THIS CODE TO REMOTE END FOR OPENING OF LINE FROM REMOTE END
3. OPEN LINE BKR AND ISOLATOR FROM UCR END4. AFTER OPENING OF LINE ISOLATOR & BREAKER FROM REMOTE END
&UCR END, INTIMATE FOR CLOSING OF LINE EARTH SWITCH AT REMOTE END.
5. NOW CLOSE EARTH SWITCH AT UCR END & INTIMATE IT TO REMOTE END6. ISSUE PTW TO EMD
NORMALIZING A FEEDER 1. ENSURE PTW CANCELLATION AND CLEARANCE FROM EMD2. INTIMATE NRLDC/CPCC/CLDS FOR ISSUE OF LINE NORMALIZATION AND
CHARGING CODE TO BOTH ENDS. CONFIRM IT FROM REMOTE END ALSO3. GIVE MESSAGE TO REMOTE END FOR OPENING OF EARTH SWITCH AND
NORMALIZATION OF LINE AND BUS ISOLATOR AT THEIR END4. AFTER GETTING CONFIRMED MESSAGE FROM REMOTE END, OPEN EARTH
SWITCH AND NORMALIZE LINE AND BUS ISOLATOR AT UCR END’5. INTIMATE IT TO REMOTE END BY WRITTEN MESSAGE AND REQUEST FOR
CHARGING OF LINE FROM REMOTE END UNDER INFORMATION TO UCR END6. AFTER GETTING CLEARANCE FOR CHARGING FROM REMOTE END,
SYNCHRONIZE THE LINE(WITH THE HELP OF SYNCHRONIZING TROLLEY)FROM UCR END
7. OBSERVE LINE V & I OF ALL 3 PHASE; IN CASE OF ABNORMALITY INFORM TO EMD
VARIOUS ALARMS
ALARMS ON CONTROL PANEL- THEY TELL US THE FINAL ACTION OR STATE
FLAGS ON RELAY PANEL- THEY HELP US TO FIND OUT THE CAUSE
CONTROL PANEL
RELAY PANEL
ALARMS RELATED TO GT PROTECTION
• BKR TC1/TC2 FAULTY• LBB PROTECTION OPERATED• BREAKER AUTO TRIP• BREAKER GENERAL LOCKOUT• BREAKER POLE DISCREPENCY• PANEL DC-1 FAIL• PANEL DC-2 FAIL
ALARMS RELATED TO ST PROTECTION
• BKR TC1/TC2 FAULTY• LBB PROTECTION OPERATED• BKR AUTO TRIP• BKR GENERAL L/O• BKR POLE DISCREPENCY• TRAFO O/C & E/F PROTECTION OPERATED• TRAFO BUCHHOLZ RELAY OPERATED• TRAFO OIL TEMP/WDG TEMP TRIP• EARTH TRAFO TRIP• TRAFO PRV1/PRV2 OPERATED• TRAFO DIFFERENTIAL OR REF PROTECTION OPERATED• PANEL DC1 FAIL• PANEL DC2 FAIL• OVER FLUXING PROTECTION
ALARMS RELATED TO FEEDER PROTECTION
• BKR TC1/TC2 FAULTY• LBB PROTECTION OPERATED• BKR GENERAL L/O• BKR AUTO TRIP• FAULT LOCATOR DC FAIL• DISTANCE RELAY ACQUISITION UNIT FAILURE• AUTO RECLOSE L/O• PLCC CHANNEL 1/2 FAIL• PANEL DC FAIL• POWER SWING DETECTED• OVERVOLTAGE OR BROKEN CONDUCTOR• MAIN 1/2 CARRIER RECEIVED• MAIN 1/2 DIRECT TRIP
PROTECTION PHILOSOPHIES
• PROTECTION OF BUS BAR • PROTECTION OF FEEDER• PROTECTION OF STATION TRANSFORMER
BUS BAR PROTECTION
PRINCIPLE: CIRCULATING CURRENT DIFFERENTIAL PRINCIPLE
CURRENT DISTRIBUTION – EXTERNAL FAULT
CURRENT DISTRIBUTION FOR INTERNAL FAULTS
PRACTICAL VARIANTS OF BBP
• HIGH IMPEDANCE TYPE
• LOW IMPEDANCE BIAS TYPE
HIGH IMPEDANCE TYPE
Relay Branch made High Impedance to limit differential current due to unequal CT saturation on external fault.
Reqires exclusive CT core of identical ratio and rating.
Simple in design and execution.
LOW IMPEDANCE (BIASED) TYPE
• Through current Bias increases differential pick-up on external fault to ensure stability.
• Tolerant to CT mismatch and can use shared core.• Comparatively more complex in design and execution.• Practical schemes provide CT saturation detectors to enhance stability.
FEEDER PROTECTION
VARIOUS PROTECTIONS APPLIED TO FEEDERSARE:1. DISTANCE PROTECTION2. OVERCURRENT PROTECTION3. CARRIER CURRENT PROTECTION
OTHER PROTECTIONS INCLUDE:UNDERVOLTAGE PROTECTION
CLASSIFICATION
1. Protection against Electrical FaultsUnit Protection (against Internal Faults) Differential Protection. REF Protection.
Non-Unit Protection (against un cleared external faults) IDMT O/C, E/F Relays. Definite Time O/C, E/F Relays.
2.Protection against Abnormal Conditions Over Load protection Over Fluxing Protection
3. Protective Devices (Non-electrical) Buchholz (Main Tank / OLTC) Oil / Winding Temperature Indicators / Relays Pressure Release Valve Oil Level Gauges / Indicators
TRANSFORMER PROTECTION
EFFECTS OF VARIOUS SWITCHYARD EMERGENCIES ON GENRATOR
1.FEEDER FAULT BUT AUTORECLOSE SUCCESSFUL
2.UNSUCCESSFUL AUTORECLOSE- TRIPPING OF FEEDER AND LOCKOUT
3.MULTIPLE FEEDER TRIPPING4.BUS BAR FAULT
CASE 1
• ROTOR WILL SPEED UP A BIT WHICH WILL CAUSE IN AN INCREASE IN THE POWER ANGLE
• STABLE POWER SWINGS WHICH WILL SLOWLY DAMP OUT
• NO PERSISTENT CHANGE IN THE GENERATOR O/P
CASE 2
• FOR A SINGLE FEEDER TRIP THERE WILL BE SUDDEN LOSS OF HUGE LOAD ON THAT BUS WHICH WILL CREATE TRANSIENT IN SYSTEM
• POWER SWINGS WILL OCCUR• BECAUSE OF INTERCONNECTION OF ALL THE
BUSES WE CAN STILL MAINTAIN ALL THE UNITS BUT AT A SLIGHTLY REDUCED LEVEL
CASE 3
• DEPENDING UPON THE MAGNITUDE OF LOSS OF LOAD WE MAY HAVE TO SUBSTANTIALLY REDUCE THE LOAD ON ALLL THE UNITS
• IN WORST CASES WE HAVE TO SHUT DOWN UNITS TO REDUCE INFEED ON EACH BUS
CASE 4
• INSTANTANEOUS TRIPPING OF : 1. BUS COUPLER OF CONCERNED BUS 2. BUS SECTIONALIZER OF CONCERNED BUS 3. A VERY SEVERE TRANSIENT 4. ALL THE GENERATORS CONNECTED TO THAT
BUS 5. TRIPPING OF ALL FEEDERS AND STs
CONNECTED TO THAT BUS
• IN THIS CASE WE MAY HAVE TO REDUCE LOAD ON REST OF THE UNITS ALSO BY SMALL AMOUNTS BECAUSE WE REMOVED THE INTERCONNECTION OF BUSES
EFFECTS OF FAULTS – CTD.
CROSSING THE ELECTRICAL REGIME AND ENETRING INTO MECHANICAL ASPECTS:
• HUGE TORSIONAL STRESSES ARE DEVELOPED IN GENERATOR AND TURBINE SHAFTS DUE ELECTRICAL DISTURBANCES
• THESE MAY RESULT IN TOTAL FATIGUE
CONDITION MONITORING OF SWITCHYARD EQUIPS.
EARTHING AND SAFETY OF PERSONAL
1. THE OBJECTIVE OF EARHING IS TO MAINTAIN A LOW POTENTIAL ON ANY OBJECT
2. IN A SUBSTATION AREA EARTHING LIMITS THE POTENTIAL GRADIENT WITHIN AND IMMEDIATELY OUTSIDE THE AREA TO A VALUE, SAFE FOR THE WORKING PERSONNEL.
REQUIREMENT OF A GOOD EARTHING • THE EARTH RESISTANCE FOR THE SWITCHYARD AREA
SHOULD BE LOWER THAN A CERTAIN LIMITING VALUE“RA” IN ORDER TO ENSURE THAT A SAFE POTENTIALGRADIENT IS MAINTAINED IN THE SWITCHYARD AREA AND PROTECTIVE RELAY EQUIPMENT OPERATE SATISFACTORILY. FOR MAJOR SWITCHYARDS AND SUBSTATIONS IN INDIA, THIS LIMITING VALUE OF EARTH RESISTANCE (RA) IS TAKEN TO BE LESS THAN 0.5 OHM.
• THE GROUNDING CONDUCTOR MATERIAL SHOULD BE CAPABLE OF CARRYING THE MAXIMUM EARTH FAULT CURRENT WITHOUT-OVERHEATING AND MECHANICAL DAMAGE. THE MAXIMUM FAULT LEVEL IN THE 220 KV SYSTEM HAS BEEN ESTIMATED TO BE 30 KA AND THIS VALUE OF FAULT CURRENT IS USED IN THE DESIGN OF EARTH MAT FOR THE 220 KVSUBSTATION.
THANK YOU
LBB PROTECTION (50Z)
• Provides local isolation when breaker gets stuck on fault.
• Ensures comparatively faster clearance than remote backup.
TRANSFORMER PROTECTION
Buchholz Relay
Petcock
From transformer
Deflector plate
Trip bucket
To oilconservator
Mercury switch
Alarm bucket
Transformer
To oil conservator
Bucholtz Protection Application
Accumulation of gas
Oil Leakage
Severe Winding Faults
Colour of gas indicates the type of fault
White or Yellow : Insulation burnt
Grey : Dissociated oil
Accumulation of gas
Gas can be extracted for detailed analysis
Accumulation of gas
Severe winding fault
Severe winding fault
Severe winding fault
Pressure Relief Valve The pressure relief valve (PRV ) is designed as
a safety device to be used on power transformer and similar oil filled electrical equipments . When pressure in tank rises beyond predetermined safe limit , the PRV operates and performs following functions
1.Reduces the pressure in the 2.Secondly, along with above mentioned
function ,operates a switch which can be used to initiate precautionary electrical system
Overfluxing
Transient Overfluxing - Tripping of differential element Prolonged Overfluxing - Damage to transformers Here value of k=1.25
Effects
m2
I e
m
V = k
Overfluxing - Condition Differential element should be
blocked for transient overfluxing-+
25% OVERVOLTAGE CONDITION
43% 5TH HARMONIC CONTENT
Overfluxing waveform contains very high 5th Harmonic content
V = Kf
• Trip and alarm outputs for clearing prolonged overfluxing
• Alarm : Definite time characteristic to initiate corrective action
• Trip : IT or DT characteristic to clear overfluxing condition
Overfluxing - Protection
DISTANCE PROTECTION
What is distance protection?
RELAY
IntendedREACH point
Z
Transient Overreach
• Fault current generally contains dc offset in addition to ac power frequency component
• Ratio of dc to ac component of current depends on instant in the cycle at which fault occurred
• Rate of decay of dc offset depends on system X/R
Typical load characteristic impedance
+R
Operate
area
No Operate area
+XL
+ = LOOKING INTO LINE normally considered forward
Load Trajectory
Rea
ch
Load Swings
Typical Protection SchemesLong Lines
• Phase comparison• Directional Comparison Blocking (DCB)• Permissive Underreach Transfer Trip (PUTT)
Distance Schemes
Pilot Aided Schemes
No Communication between Distance
Relays
Communication between Distance
relays
Non-Pilot Aided Schemes
(Step Distance)
Bus
Line
Bus
Zone 1
Zone 2
Zone 2
Zone 1
To protect end ofline
& Local Trip Zone 2
Rx
OR Zone 1
PUTT Scheme