400 kv swyd for doj
TRANSCRIPT
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Understanding basics of switchyard
Switchyard equipments and schemes
Functions of various equipments
Brief description of modes of transmission
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What is a Switchyard ?What is a Switchyard ?It is a switching station which has the following credits :It is a switching station which has the following credits :
(i) Main link between Generating plant and(i) Main link between Generating plant and
Transmission system, which has a large influence onTransmission system, which has a large influence on
the security of the supply.the security of the supply.
(ii) Step-up and/or Step-down the voltage(ii) Step-up and/or Step-down the voltage
levels depending upon the Network Node.levels depending upon the Network Node.
(iii) Switching ON/OFF Reactive Power Control(iii) Switching ON/OFF Reactive Power Control
devices, which has effect on Quality of power.devices, which has effect on Quality of power.
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Power evacuation from switchyardPower evacuation from switchyard
400 KV LINES400 KV LINES
VINDHYACHAL-JABALPUR # 1VINDHYACHAL-JABALPUR # 1 VINDHYACHAL-JABALPUR # 2VINDHYACHAL-JABALPUR # 2
VINDHYACHAL-JABALPUR # 3VINDHYACHAL-JABALPUR # 3 VINDHYACHAL-JABALPUR # 4VINDHYACHAL-JABALPUR # 4 VINDHYACHAL- SATNA # 1VINDHYACHAL- SATNA # 1 VINDHYACHAL- SATNA # 2VINDHYACHAL- SATNA # 2
VINDHYACHAL- SATNA # 3VINDHYACHAL- SATNA # 3 VINDHYACHAL- SATNA # 4VINDHYACHAL- SATNA # 4 VINDHYACHAL- KORBA # 1VINDHYACHAL- KORBA # 1 VINDHYACHAL- KORBA # 2VINDHYACHAL- KORBA # 2
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POWER ALLOCATIONPOWER ALLOCATION
Stage I & II Stage IIIStage I & II Stage III
Gujrat 23.6% 23.9%Gujrat 23.6% 23.9% MH 36.1% 31.9%MH 36.1% 31.9%
MP 29.5% 23.1%MP 29.5% 23.1%
CG 3.4% 4.2%CG 3.4% 4.2% Goa, daman, dadar 7.4% 1.9%Goa, daman, dadar 7.4% 1.9%
& nagar haweli& nagar haweli
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Type of
Clearance
400 KV
Phase toEarth
clearance
3800mm
Phase to
Phase
clearance
4000 mm
Section
clearance
6500 mm
The minimum clearances for 400 KV switchyard are as follows:
Clearances
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400 KV
Highest System Voltage 420 KV RMS
Lightning Impulse Voltage 1425 KVp
Switching Impulse Voltage 1050 KVp
Power Freq withstand
voltage for 1 minute
630 KV RMS
MaximumFault Level (for1 second) 40 KA
Minimum Creepage dist 10500 mm
parameters
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OUTGOING LINE
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PICTORIAL VIEW OF 400KV SWITCHYARD AT
VSTPS
http://var/www/apps/conversion/current/tmp/scratch17457/sld%20of%20all%20stages%20switchyard.pdfhttp://var/www/apps/conversion/current/tmp/scratch17457/sld%20of%20all%20stages%20switchyard.pdf -
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Bay DetailsBay DetailsThere are 38 nos. of 400 KV bays in VSTPSThere are 38 nos. of 400 KV bays in VSTPS
switchyard.switchyard.
1) 10 Nos. of 400 KV, GT Bay1) 10 Nos. of 400 KV, GT Bay2) 3 Nos. of 400/132 KV, 200 MVA ICT Bay2) 3 Nos. of 400/132 KV, 200 MVA ICT Bay
3) 10 Nos. of 400 KV Line Bay3) 10 Nos. of 400 KV Line Bay
4) 4 Nos. of 400 KV Bus Sections4) 4 Nos. of 400 KV Bus Sections
5) 3 Nos. of Bus Coupler Bay5) 3 Nos. of Bus Coupler Bay6) 3 Nos. of Transfer Bus Coupler6) 3 Nos. of Transfer Bus Coupler7) 2 Nos. of HVDC bay7) 2 Nos. of HVDC bay
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Equipments commonly found in switchyard :Equipments commonly found in switchyard :
Circuit breakerCircuit breaker IsolatorIsolator Instrument transformerInstrument transformer
Surge arrestorSurge arrestor Shunt reactorShunt reactor Wave trapWave trap Inter connecting transformerInter connecting transformer Neutral grounding reactorNeutral grounding reactor Post insulatorPost insulator DC systemDC system EarthingEarthing
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Functions of various equipments :Functions of various equipments :
Circuit breakers :Circuit breakers :
-- Makes or automatically breaks the electrical circuits underMakes or automatically breaks the electrical circuits underLoaded condition.Loaded condition.
Isolators :Isolators :
-- Opens or closes the electrical circuits under No-loadOpens or closes the electrical circuits under No-loadconditions.conditions.
Instrument transformers :Instrument transformers :-- For stepping-down the electrical parameter (Voltage orFor stepping-down the electrical parameter (Voltage or
Current) to a lower and safe value for Metering andCurrent) to a lower and safe value for Metering andProtection logics.Protection logics.
Lightning arrestorsLightning arrestors
-- Safe guards the equipment by discharging the high currentsSafe guards the equipment by discharging the high currentsdue to Lightning.due to Lightning.
Earth switch :Earth switch :
-- Used to connect the charged body to ground to dischargeUsed to connect the charged body to ground to dischargethe trapped charge to have a safe maintenance zone.the trapped charge to have a safe maintenance zone.
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Post insulatorPost insulator::
-- used for supporting bus bars, CTs, PTs, CBs etc.used for supporting bus bars, CTs, PTs, CBs etc.
ICTICT::-- used to interconnect two grids/system operating at twoused to interconnect two grids/system operating at twodifferent voltages.different voltages.
NGRNGR::
-- used for low impedance grounding of high voltage systemused for low impedance grounding of high voltage systemto limit the line to ground fault current under system faultto limit the line to ground fault current under system faultconditions.conditions.
DC systemDC system::
-- required for control and protection supply for switchgear,required for control and protection supply for switchgear,
indications, annunciation system and also for emergencyindications, annunciation system and also for emergencylighting.lighting.
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Overhead earth wireOverhead earth wire ::
-- Protects the O/H transmission line from Lightning strokes.Protects the O/H transmission line from Lightning strokes.
Bus barBus bar ::
-- Conductors to which a number of circuits are connected.Conductors to which a number of circuits are connected.
Wave Traps/Line trapsWave Traps/Line traps ::
-- Used in PLCC circuits for Communication and telemetering.Used in PLCC circuits for Communication and telemetering.
Reactive Power control devicesReactive Power control devices ::
-- Controls the reactive power imbalance in the grid byControls the reactive power imbalance in the grid by
switching ON/OFF the Shunt Reactors, Shunt Capacitors etc.switching ON/OFF the Shunt Reactors, Shunt Capacitors etc.
Current Limiting ReactorsCurrent Limiting Reactors ::
-- Limits the Short circuit currents in case of fault.Limits the Short circuit currents in case of fault.
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Can break or make the circuit on load and even on faults.
SF6gas is used for arc quenching medium since it has outstanding arc-
quenching properties and very good dielectric strength .
Each pole of breaker consists of 2 interrupter unit, a bell crank
mechanism with grading capacitors & PIR.
Bell Crank Mechanism converts the vertical movement of operating
rod into linear horizontal movement of moving parts of interrupter &
PIR.
Grading Capacitor ensures uniform voltage distribution in open
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400 KV Circuit Breaker parameters
Rated Voltage 420 kV (rms)
Rated continuous current minimum 2000A/3150A
Rated short ckt breaking current 40 kA
Rated short ckt making current 2.5 x 40 kA
Rated short ckt current duration 3 sec
Closing time 100 ms (max)
Opening time 22 ms (max)
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Operates on no load.It is not meant for breaking load currents. It merely acts as a
disconnecting switch for isolation of equipments from live parts
when required for maintenance purpose.
It can be opened only when Circuit Breaker is in open position.
Types of Isolators:-
Horizontal Centre Break isolator
Pantograph Isolator
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Pantograph Isolator:-
TECHNICAL PARAMETERS
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TECHNICAL PARAMETERS
400KV ISOLATOR
Rated voltage 420 kV (rms)
Rated continuous current 2000 A/3150 A
Rated insulation level
1) Rated one minute power frequency withstand voltage
520 KVrms (between live terminals and earth)
610 KVrms (across isolating distance)
2) Rated lightning impulse withstand voltage1425 KV
P(between line terminals and earth)
1425 KVP
impulse on one terminal and 240 KVP
power
frequency voltage of opposite polarity on other terminals.
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Instrument transformers are used for measurement and
protection purposes.Types :-
1) Current Transformer:-
Steps downs current from high to low value.
Connected in series with the main circuit
2) Capacitor Voltage Transformer:-
Capacitor voltage divider type with electromagnetic unit
(EMU). EMU comprises of compensating reactor,
intermediate transformer, protective and damping devices.
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400KV CLASS CT
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400KV CLASS CVT
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ECHNICAL PARAMETERS
00KV CT (OIL FILLED TYPE)
Rated current 2000A(peak)
Number of cores 5(Four for protection
& one for metering)
Rated frequency 50 Hz
System neutral earthing effectively earthed
Rated system voltage 420 kV (rms)
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CAPACITOR VOLTAGE TRANSFORMER (CVT)
PARAMETERS 400kV
Rated frequency 50 Hz
System neutral earthing effectively earthed
Rated voltage 420 kV (rms)
Rated total thermal burden 750 VA
Number of cores 5(five)
Installation outdoor Rated insulation level
1) 1.2/50 microsecond impulse 1425 kVP
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2.4 SURGE ARRESTOR
Provides protection against lightning or any surge developing.
Discharges high frequency over voltages to the ground.
Non linear characteristics.
TECHNICAL PARAMETERS
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TECHNICAL PARAMETERS
Particular 400 kV
Rated system voltage 420 kV
Rated arrestor voltage 390 kV
Minimum discharge capability 8 kJ/kV corresponding to minimum
discharge characteristic
Switching surge residual voltage (1kA) 730 kVP- minimum
780 kVP maximumOne minute power frequency withstand
voltage of arrestor housing
630 kV(rms)
Impulse withstand voltage of arrestor 1425 kVP
Maximum residual voltage at
1) 10 kA nominal discharge current
2) 20 kA "
900 kVP
975 kVP
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2.5 SHUNT REACTOR
Provided at sending & receiving end of long transmission line Switched on when the line is to be charged or line is on low load to
avoid Ferranti Effect by neutralizing shunt capacitance of such lines.
TECHNICAL PARAMETERS
Rated voltage 420 kV Rated MVAR 50 at rated voltage Number of phases 3 System fault level 40 kA
Connection with neutral through load
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Insulation level
1) Lightning impulse 1.2/50 1300 kV(peak)
microsecond withstand voltage
2) Switching surge withstand voltage 1050 kV(peak)
3) One minute power frequency 630 kV(rms)
withstand voltage
Cooling system ONAN
Ratio of zero sequence reactance
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400KV CLASS SHUNT REACTOR
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2.6 POST INSULATOR
It is used for supporting bus bars, CTs, PTs, CBs etc. in the
switchyard. Post type insulator consists of a particular part
permanently secured in a metal base to be mounted on the
supporting structure.
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2.7 WAVE TRAP
Wave trap is inserted into high voltage transmission line to prevent
undue loss of carrier signal for all power system conditions.
Its impedance is negligible at power frequency so as not to disturb
power transmission but is relatively high over the frequency band of
carrier .
TECHNICAL PARAMETERS
Rated power frequency 50 Hz
Rated system voltage 400 kV
Rated continuous current 2000 A/3150 A
Type of tuning Broad band
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2.8 INTERCONNECTING TRANSFORMER:-
Are normally autotransformer
Used to interconnect two grids/system operating at two differentsystem voltages (ie.400/132 KV).
Characterized by wide tapping range & an additional tertiary
winding which may be loaded or unloaded. Unloaded tertiary
winding acts a stabilizing winding by providing a path for the thirdharmonic currents.
TECHNICAL PARAMETRS:-
MVA Rating 200/120/80
Voltage Ratio 400/132/33 KV
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Insulation level:
HV winding-
1. Lightning impulse withstand voltage 1425 KVp
2.CW Impulse withstand voltage 1570 KVp
LV winding-
1.Lightning impulse withstand voltage 250 KVp
2.CW Impulse withstand voltage 90 KVrms
MV winding-
1. Lightning withstand voltage 650 KVp
2. Magnetizing inrush current (Amps) 4 times the rated
current
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ICT
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2.9 NEUTRAL GROUND REACTOR(NGR):-
Neutral grounding reactors are used for lowimpedance grounding of high voltage systems.
They limit the line to ground fault current undersystem fault conditions by providing additionalreactance which neutralizes the capacitive currents.
RatingUnder balanced operating conditions, there isessentially no continuous current flowing through theneutral grounding reactor. Therefore, the rated
current of this reactor is considered to be the thermalshort time current under fault conditions . Theduration of the short time rating is time dependent,and is specified as 10 sec or 1minute
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2.10 DC SYSTEM
DC is required for control and protection supply forswitchgear, indications, annunciation system, communication
system etc. DC supply is also required for emergency lighting.
The commonly used voltage levels are 220 V for motors, for
controls & protection schemes and 48 V for communication.
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Modes
of
Transmission
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-- Power can be generated at high voltages.Power can be generated at high voltages.
- Step-up/Step-down is possible.- Step-up/Step-down is possible.
-- Requires more copper.Requires more copper.- Due to Skin effect, the effective- Due to Skin effect, the effectiveresistanceresistance is increasedis increased
- Continuous loss of power due to charging current even- Continuous loss of power due to charging current even
when the line is open.when the line is open.
- Requirement of Transposition of conductors.- Requirement of Transposition of conductors.
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-- Low cost due to less copper requirementLow cost due to less copper requirement
- No Stability and synchronizing problems.- No Stability and synchronizing problems.
- Asynchronous lines (Interregional ties)- Asynchronous lines (Interregional ties)
- No increase in Fault level if interconnected.- No increase in Fault level if interconnected.- Less Corona and RI.- Less Corona and RI.
- Better Voltage regulation due to absence of- Better Voltage regulation due to absence ofInductance.Inductance.
- Requires less insulation as the potential stress is less.- Requires less insulation as the potential stress is less.
-- Higher generation is not possible due toHigher generation is not possible due tocommutationcommutation
- Step-up/Step-down is not possible.- Step-up/Step-down is not possible.
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km
Cost
100 300 1100500 700 900
Break Even distance
HVDC Preferred
EHVAC Preferred
Cost of
Substation
HVDC
Line
EHVAC
Line
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