400kv Substation Training Report 5rd3a

-Shailendra Yadav EE-42(0705420096) 1

INTRODUCTION OF SUBSTATION It is situated at 26°34’2’’N & 80°32’57’’E coordinates in Dahi Chowki 6.64 km far from Unnao railway station. Constructed during 1994-98 by CGL. The whole substation is divided in three parts: 132kv switchyard 400/220kv switchyard 765kv switchyard (Under construction)

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INCOMING & OUTGOING LINE OF SUBSTATION •Unnao to Lucknow (400KV & 220KV both separate) •Unnao to Bareily-1 (400KV) •Unnao to Bareily-2 (400KV) •Unnao to Agara (400KV) •Unnao to Panki Kanpur(400KV & 220KV both separate) •Unnao to Anpara (400KV) •Unnao to PGCIL Lucknow-1 (400KV) •Unnao to PGCIL Lucknow-2 (400KV) •One bus bar for 400/220KV 315MVA ICT-1 & ICT-2 line.

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OUTDOOR EQUIPMENT USED IN SUBSTATION           

Two 100MVA 220/132KV transformer Two 315MVA 400/220KV transformer Shunt reactor Capacitor bank SF6 circuit breaker Isolators Lightning arresters Current transformer Capacitor voltage transformer Wave trap Isolators

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ConservaterTank

Transformer

H.V. side bushing CT

COOLING SYSTEM (ONAN)

L.V. side bushing CTs 5

Radiator plates

Oil pump is used for circulating oil forcelly. Radiator plates are used for increasing surface area for natural air cooling.

Oil pump

Earthing plate

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COOLING FANS

 we use Cooling fans for forced air cooling of transformer . Total six fans are used for each 100MVA and eight fans are used for each 315 MVA transformer. But all fans never start at same time . It start in pairs .

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Tertiary terminal

Tertiary terminal mostly opened. The output voltage of tertiary terminal is 11KV in 100MVA transformer and 33KV in 315 MVA transformer OLTC chamber

Pressure relief valve box

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TERMINALS ON TANK COVER

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In these photos we can see fogging near transformer due to operation fire protection system.

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BUCHHOLZ RELAY Buchholz relay is a safety device mounted on some oil-filled power transformers and reactors. It is used as a protective device sensitive to the effects of dielectric failure inside the equipment.

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OTI & WTI OTI

WTI

OTI –oil temp. indicator measure temp. of oil filled in transformer. In OTI has two mercury bulb. WTI- winding temp. indicator measure winding temp of transformer. It has four mercury bulb. mercury bulb

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CURRENT TRANSFORMER In electrical engineering, a current transformer (CT) is used for measurement of electric currents. Current transformers, together with voltage transformers (VT) (potential transformers (PT)), are known as instrument transformers. When current in a circuit is too high to directly apply to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments.

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PROTECTION DIAGRAM

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CAPACITOR VOLTAGE TRANSFORMER A capacitor voltage transformer (CVT) is a transformer used in power systems to step-down extra high voltage signals and provide low voltage signals either for measurement or to operate a protective relay. The device has at least four terminals, a high-voltage terminal a ground terminal and at least one set of secondary terminals. CVTs are typically single-phase devices 15

Cross sectional view of CVT 1 - Primary terminal 2 - Cast aluminum bellow housing 3 - Stainless steel expansion bellow 4 - Compression spring 5 - Insulated voltage connection 6 - Capacitor elements 7 - Insulator (porcelain or composite) 8 - Voltage divider tap connection 9 - Cast-epoxy bushing 10 - HF terminal connection 11 - Ferro-resonance suppression device 12 - Secondary terminals 13 - Oil level sight-glass 14 - Aluminum terminal box 15 - Intermediate transformer 16 - Oil/air block 17 - Oil sampling device 18 - Compensating reactor 19 - Aluminum cover plate

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PRINCIPLE CIRCUIT DIAGRAM OF CVT 1. High Voltage terminal 2. Compensation reactor 3. Intermediate voltage transformer 4. Ground terminal 5. Ferro-resonance suppression device 6. Damping resistor 7. Carrier (HF) terminal (optional) 8. Overvoltage protective device 9. Secondary terminals 10. Link, to be opened for test purposes

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CIRCUIT BREAKER A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. In this image we can see a SF6 circuit breaker with double break system.

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ISOLATORS An isolators switch are used to completely deenergized an electrical circuit. High-voltage isolation switches are used in electrical substations to allow isolation of apparatus such as circuit breakers and transformers, and transmission lines, for maintenance.

Isolating rod

Earth link rod

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PANTOGRAPH ISOLATORS In open state

In close state

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Central rotating double break isolator

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Wave trap  Wave trap are used in power system for carrier communication.  It trap the higher frequency above 50Hz.  It is the effort to utilize the same transmission line between two substation for the purpose of communications

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LIGHTNING ARRESTOR The overvoltage protection is obtained by the use of lightning / surge arresters. Lightning Arresters or Surge Arresters are always connected in Shunt to the equipment to be protected, they provide a low impedance path for the surge current to the ground. Mostly in present days zinc oxide (ZnO) gapless arresters are in use. 24

INTERPOSING C.T. The interposing CTs are used for Power transformer Differential Protection circuit. In a delta/Star Power transformer, the cts will be connected star and delta formation, for eliminating Zero sequence current on star side. There will be mismatch of secondary current , to maintain equilibrium, interposing Cts will be connected to Delta formed CTs. 25

RELAYS

RES E/F +O/L Protection relay

Differential relay O/F protection +FFR Group A trip relay

Breaker failure relay O/C protection relays

CB trouble relay Group B trip relay

DR earth switch relay

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Relay conti…. A outer view of Relay

Relay testing box

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SHUNT REACTOR  Shunt Reactor is a thyristor controlled high impedance

transformer. A stable bus voltage can be maintained by providing variable reactive power based on the bus voltage deviations due to the load variations. 28

SHUNT CAPACITOR BANK Shunt capacitor banks are used to improve the quality of the electrical supply. provide capacitive reactive compensation. Power factor correction.

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