Sharavati receiving station

substation

1. Sharavathi Receiving Station Hootagalli Substation , Mysuru NIE INSTITUTE OF TECHNOLOGY To Assistant Executive Engineer KPTCL,SRS Hootagalli Substation, Mysuru BY H . C . Naveen . Kumar (4NN14EE013 ) D . V . Manjunath (4NN14EE012)

2. CONTENT Introduction About Hootagalli SRS Substation Single Line Diagram of SRS List of component in Substation Description of the yard Control Room Battery Room

3. INTRODUCTIOIN Sharavati Hydroelectric project Originating at a height of 730 m near Ambuthirtha, in Shimoga district, the Sharavathi river flows in a north-west direction . In its long, 132-km journey, i t is joined by several tributaries after a stretch of 80 km along its course, the river drops down a steep mountain face of 293m – spectacle known as the Jog Falls.   The Sharavati Hydroelectric project was started to tap the electricity generating potential of the river, three power generating stations in this project The Sharavati Generating Station with 10 Units and an installed capacity of 1035 MW The Linganamakki Dam Powerhouse with 2 units and an installed capacity of 55 MW The Gerusoppa Dam Project with 4 units totalling to 240 MW. The KPCL blueprint identifies Sharavathi as its “Master Station” – a headpoint that will control all peripheral stations through a nodal monitoring system. The prime objective here is to optimize power generation through a systematic integration of several reservoirs and water conductor systems.

4. About Hootagalli SRS Station A substation is an assembly of apparatus, which transform’s the characteristics of electrical energy from one form to another , from one voltage level to another level. Hence a substation is an intermediate link between the generating station and the load units. There are total three, 220KV incoming feeders in SRS receiving station Kadakola Line Basthipura no 1 line Basthipura no 2 line The incoming feeders are connected to bus-bar through lightning arresters , line isolator, circuit breakers , current-transformers etc. .The bus-bars are to have an arrangement of auxiliary bus. The incoming 220KV supply is stepped down to 66KV using 100MVA transformer. The 220KV SRS station consist of 3 nos. of 100MVA transformer, with there voltage ratio respectively are 220/66/11kv. The incoming 220kv line also forwarded to other region, there is one 220KV outgoing line to Vijaymangala.

5. SINGLE LINE DIAGRAM OF 220 KV SRS HOOTAGALLY,MYSORE

6. Components in the P ower station Power transformer: 100MVA &12.5MVA Circuit breakers:220KV,110KV,66KV,11KV 66KV capacitor banks Potential transformer:220KV bus PT,66KV bus PT Current transformer:220KV,66KV,11KV Capacitor voltage transformers: 220KV ,66KV Isolator : 220KV,66KV,11KV Lightning arrestor:220Kv,66KV Auxiliary transformer Battery and battery charger Relays Centralized air compressor

7. Power Transformer A static electrical machine used for transforming power from one circuit to another circuit without changing frequency is termed as power transformer . The transformers are generally used to step down or step up the voltage level of a system for transmission and generation purpose. Description of the yard

8. Circuit Breaker Operation A circuit breaker can make or breaker circuit either manually or automatically under all condition as no load , full load and short circuit condition. Circuit breaker essentially consists of fixed and moving contacts. These contacts can be opened manually or by remote control whenever desired. When a fault occurs on any part of the system, the trip coils of breaker get energized and the moving contacts are pulled apart by some mechanism, thus opening the circuit. When contacts of a circuit breaker are separated, an arc is struck; the current is thus able to continue. The production of arcs are not only delays the current interruption, but is also generates the heat. Therefore, the main problem is to distinguish the arc within the shortest possible time so that it may not reach a dangerous value SF6 circuit breaker: Current interruption in a high-voltage circuit breaker is obtained by separating two contacts in a medium, such as sulfur hexafluoride (SF6), having excellent dielectric and arc-quenching properties. After contact separation, current is carried through an arc and is interrupted when this arc is cooled by a gas blast of sufficient intensity. Types of Circuit breaker 1.Oil Circuit Breaker 2.Air -Blast Circuit Breaker 3.Sulphur Hexafluoride Circuit Breaker (Sf 6 )

9. CAPACITOR BANK Capacitor bank accomplishes following operations 1. Supply reactive power 2. Increases terminal voltage 3. Improve power factor  The load on the power system is varying being high during morning and evening which increases the magnetization current. This result in the decreased power factor. The low power factor is mainly due to the fact most of the power loads are inductive and therefore take lagging currents. The low power factor is highly undesirable as it causes rise in current, resulting in additional losses. In order to improve the power factor come device taking leading power should be connected in parallel with the load. One of the such device can be capacitor bank. The capacitor draws a leading current and partly or completely neutralize the lagging reactive component of load current.

10. CURRENT TRANSFORMER Current transformer is used for measurement of the altering current by taking samples of high current of the system. These reduced samples are in accurate proportions with actual high current of system. These are used for installation and maintenance of current relay in substation for protection purpose which are normally have low-current for their operation

11. POTENTIAL TRANSFORMER Potential transformer is quite similar to the current transformer, but it is used for taking samples of high voltages of a system for providing low-voltage to the relays of protection system and also to the low-rating meter for voltage measurement. From this low-voltage measurement, actual system’s high voltage can be calculated without measuring high voltage directly to avoid the cost of the measuring system .

12. BUS BAR When numbers of generators or feeders operating at the same voltage have to be directly connected electrically, bus bar is used as the common electrical component. Bus bars are made up of copper rods operate at constant voltage. The following are the important bus bars arrangements used at substations: 1. Single bus bar system. 2.Duplicate bus bar system. . In substations, it is often desired to disconnect a part of the system for general maintenance and repairs. Isolator operates under no load condition. While opening a circuit, the circuit breaker is opened first then isolator while closing a circuit the isolator is closed first, then circuit breakers. Isolators are necessary on supply side of circuit breakers, in order to ensure isolation of the circuit breaker from live parts for the purpose of maintenance.

13. Lightening Arrester The substation equipment's such as conductor, transformer etc., are always erected outdoor. Whenever light surges occur then, a high-voltage pass through these electrical components causing damage to them. Therefore to avoid this difficulty, lightening arrester are placed to pass entire lightening surge to earth.

14. Relay Relays are used for disconnected the circuit by manual or automatic operation. Relay consists of coil which is excited or energized and such that the making the contacts of relay closed ,activates the relay to break or make the connection. There are different types of relay such as current relay, microprocessor relay, mho relay, Buchholz relay etc., . The SR substation uses Buchholz relay and many other types of relays . Isolator Isolator is a manually operated mechanical switch that isolates a part of a circuit of substation meant for repair from a healthy section in order to avoid occurrence of more fault. Hence it is also called as disconnecter . There are different types of isolators such as single-break isolator, double-break isolator, bus isolator, line isolator etc.

15. Insulator The substance which does not allow free movement of electron is called as insulator. There are different types of insulators such as suspension type, strain type, pin type so on . Insulator are used or insulation purpose while erecting electric poles with conductors to avoid short circuit and for other purpose. It is used to trap the high frequency communication signals sent on the line from the remote substation and diverting them to the telecom/tele-protection panel in the substation control room. Line trap also is known as Wave trap. Wave Trap

16. Bus voltages and frequencies, line loading, transformer loading, power factor, temperature, etc. are the basic variables related with substation control and instrumentation. The various supervision, control and protection function are preformed in substation control room. The relays, protection and control panels are installed in the controlled room. These panels along with PC aids in automatic operation of various circuit breakers tap changers, auto-recloses, sectionalizing switches and other devices during faults and abnormal conditions. Control room   When the oil expands or contacts by the change in the temperature, the oil level goes either up or down in main tank. A conservator is used to maintain the oil level up to predetermined value in the transformer main tank by placing it above the level of the top of the tank. Breather is connected to conservator tank for the purpose of extracting moisture as it spoils the insulating properties of the oil. During the contraction and expansion of oil air is drawn in or out through breather silica gel crystals impregnated with cobalt chloride. Silica gel is checked regularly and dried and replaced when necessary. Conservator and Breather

17. BATTERY ROOM There is a battery room which has 110 batteries of 2 volt each for 220KV section. Therefore D.C. power available is for functioning of the control panels. A battery charger to charge the battery.  Various parts of lead acid batteries Plates Separators Electrolyte Container Terminal port Vent plugs CHARGING OF BATTERIES Initial charging It is the first charging given to batteries by which the   positive plates are converted to “lead peroxide", where as  the –ve plates will converted to spongy lead. Also in a fully charged battery the electrolyte specific gravity will be at its highest venue or 1.2 and its terminal voltage will be 24  volts.                       DISCHARGING When a fully charged battery delivers its energy out by meeting a load the lead peroxide of the +ve plates slowly gets converted to lead sulphate and the spongy lead of the –ve plates also gets converted into lead sulphate during this time the specific gravity of the electrolyte also decreases the value around 1.00 and the terminal voltage also decreases from its initial to a lower value which may be around 1.85 or 1.8.