220KV GRID SUBSTATION internship report.pptx

it is a report of training on 220 kv substation

1. 220KV GRID SUBSTATION SUBMITTED TO:- SUBMITTED BY:- MS: MAHIMA SHARMA PRAVEEN KUMAR 2 nd YEAR (EE)

2. INTRODUCTION The present-day electrical power system is A.C. i.e. electric power is generated, transmitted and distributed in the form of alternating current. The electric power is produced at the power stations which are located at favourable places, generally quite away from the consumers. It is delivered to the consumers through a large network of transmission and distribution. At many places in the line of the power system, it may be desirable and necessary to change some characteristic (e.g. voltage, A.C. to D.C., frequency, Power factor etc.) of electric supply. This is accomplished by suitable apparatus called  Substation . For example, generation voltage (11KV or 6.6KV) at the power station is stepped up to high voltage (say 220KV or 132KV) for transmission of electric power. The assembly of apparatus (e.g. transformer etc.) used for this purpose is the  substation .

3. Substations have switching, protection and control equipment and one or more transformers. In a large substation, circuit breaker are used to interrupt any short-circuits or overload currents that may occur on the network. 220kv IGN s/s is a converted, hybrid substation. It is part of transmission system. 33Kv substation is a gas insulated which is inside the control room. For communication purpose PLCC is used.

4. CONTENTS THE YARD WAVE TRAP INSTRUMENT TRANSFORMER CURRENT TRANSFORMER POTENTIAL TRANSFORMER POWER TRANSFORMER CIRCUIT BRAKERS POWER LINE CARRIER COMMUNICATION BATTERY ROOM CONTROL ROOM

5. THE YARD The yard is spread in very long area. The yard of 220 KV GSS at has various equipment installed at the yard of 220 KV GSS are:- Lighting Arrester Wave Trap Current Transformer Bus Bars Insulators Potential Transformer PLCC equipment including coupling capacitance Circuit Brakers Isolators

6. Fig:- The Yard

7. WAVE TRAP It is used to trap the communication signals & send PLCC room through CVT. Rejection filters are known as the line traps consisting of a parallel resonant circuit ( L and C in parallel) tuned to the carrier frequency are connected in series at each and of the protected line such a circuit offer high impedance to the flow of carrier frequency current thus preventing the dissipation. The carrier current used for PLC Communication have to be prevented from entering the power equipments such as attenuation or even complete loss of communication signals. Avoid carrier power dissipation in the power plant reduce cross talks with other PLC Circuits connected to the same power station.  

8. Ensure proper operating conditions and signal levels at the PLC transmit receive equipment irrespective of switching conditions of the power circuit and equipments in the stations.

9. INSTRUMENT TRANSFORMER The transformers which are used in A.C. system for the measurement of current, voltage, power and energy are called Instrument transformer. These are also used in connection with the measurement of power factor, frequency and for indication of synchronism. Instrument transformers  are high accuracy class electrical devices used to isolate or transform voltage or current levels. The most common usage of instrument transformers is to operate instruments or metering from high voltage or high current circuits, safely isolating secondary control circuitry from the high voltages or currents. The primary winding of the transformer is connected to the high voltage or high current circuit, and the meter or relay is connected to the secondary circuit.

10. CURRENT TRANSFORMER The current transformers are kept in the category of the instrument transformer. The C.T. are used to reduce/ stepping down A.C form high value to lower value for measurement / protection / control. They are usually installed in the out door switch. The primary conductor at high voltage with respect to earth. The secondary of C.T. is just like the ring type C.T. the primary winding consists of a very few turns , and therefore there is no. appreciation volt drop across injection . Current is transformed by C.T. the current transformer is used with primary winding , connected in series with the line carrying the current to be measured and therefore primary current is dependent upon load connected in the system.

11. Measurement of alternating current is one of the most frequent operation not only because of it’s inheriant but a also because it is necessary in determining other parameters of electrical circuit. A current transformer value of current is used for Indication of current kwh and kw meters Telementry Protective relay etc.   A current transformer is intended to operate normally with rated current of the system flowing through the primary winding which is increased in the series with the network .Secondary winding of current transformer Connected to measuring instruments and relay supplies currents circulating in the design of current transformer.

12. Fig:-CURRENT TRANSFORMER

13. POTENTIAL TRANSFORMER Similar to CT it is another type of instrument type of instrument transformer. Transformer used for voltage measurements are called voltage transformer or Potential transformer it may be of 1 phase or 3 phase. These transformers make the instruments suitable for measurement of high voltage and isolating then from high voltage. these transformer are connected in parallel and secondary winding is always open circuit. The primary winding of the potential transformer is connected to the main GSS LINE DIAGRAM. the primary has large no of turn in secondary, which provided step down of voltage , and then the voltmeter is connected across secondary terminal the high voltage line.

14. Some terms related to PT :-   RATED VOLTAGE :- the capacity voltage of the PT which it can stand RATED TRARNSFORMER RATIO:- The ratio of the rated primary voltage to the rated second voltage. RATED SECONDARY VOLTAGE:- 130 / root (3) = 63.3 VAR.   Voltage transformer which step down system voltage to sufficient form high value to low value are necessary in every system for Induction of d.c supply voltage conduction .

15. Fig:- Potential Transformer

16. Design and ranges are selected according to the secondary size of potential transformer for indicating instruments, meter and relays. But calibration of these instruments is done according to the primary voltage .

17. POWER TRANSFORMER The transformers are used to step down or step-up the incoming line voltage but at grid substation for the purpose of distribution. it is the main & major requirement of GSS for step down the supply voltage .The rating of transformer is taken according to the load. There are two power transformers of 100 MVA . They are used convert 220 KV/132 KV. And two power transformers are used of 20/25 MVA .which convert 132KV/33KV. Which transforms e/e energy from one voltage level to another desired level with corresponding change in current value and with out any change in frequency value.  

18. The physical basis of a transformer is mutual induction between the circuits linked by a common magnitude pulse voltage supplied to one set of winding called primary switch builds up a magnitude flux through the iron.   A transformer in simplest form consist of two magnetic coil, which are electrically separated from each other but magnetically linked through path of reluctance. The magnetic core is built up of laminations of high –grade section or other steel which are insulated from each to other by varnish or other insulation materials.  

19. In brief a transformer is a device that   Transform electric power from the one circuit to another.   It does not so without a change of frequency. It accomplishes this by electromagnetic induction. According to the number of winding placed around the core. The transformer are classified as Earthing terminals the trank .

20. Cooling systems   Pressure relief value   Bush hold relay   Dehydration breather   Rollers   Filters

21. Fig:-POWER TRANSFORMER