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  • 1. A Government of India enterprise) PROJECT REPORT ON ELECTRICAL ENGG(TRAIING) WITH RESPECT TO N.H.P.C Submitted to CHANDIGARH University, Chandigarh in partial fulfillment for the Award of the degree of B.TECH(EEE) (BECHLOR Of TECHNOLOGY) Reporting to: Mr. Jamil Akhtar , Pervesh Thakur,Dm(e&c By: Ajay Kumar Rana(358), Aja Btech EEE CGC GHARUAN MOHALI,
  • 2. NHPC - AN OVERVIEW •Set up in 1975 with an authorized capital of Rs. 200 Crores. •Single largest organization for hydro power development in India in the central sector •Capabilities to undertake all the activities from conceptualization to commissioning in relation to setting up of hydro power projects •Schedule ‘A’ Enterprise w.e.f. 15.5.1990. •NHPC has been granted ISO 9001 Certificate for its quality system. •Installed capacity : 2475 MW •Projects constructed on Turnkey/deposit basis : 3 •Projects under O&M : 7 •Projects under construction : 11 •Projects under investigation : 20 •Projects under joint ventures : 4 •Projects under construction •On turnkey/deposit basis : 2 SALAL AN OVERVIEW State : Jammu & Kashmir District : Reasi Dam Site : Dhyangarh in Reasi River : Chenab Capacity : 6 X 115 MW Annual Generation Target : 3100 MU Rated Head : 94.5 m Total Reservoir Capacity : 285 million Cumecs Rockfill Dam : 1 Concrete Dam : 1 Penstocks : 6 Tail Race Tunnels : 2 Tariff Rate : 41.56 paise/unit
  • 3. TECHNICAL FEATURES • 118 m high, 630m long rockfill dam. • 113 m high, 450 m long concrete dam • 11 m dia, 2.46 km long tail race tunnel. • 6 nos. Penstocks 5.23 m dia, 279 m long each. • Sub-surface power house containing 6 units of 115 MW each. Salal Hydroelectric Power Station Stage-I of 345 MW (115X3) and Stage-II of 345 MW (115X3) is constructed on river Chenab in the state of Jammu & Kashmir. The project was conceived in 1920. The feasibility studies on the project commenced in 1961 by the state government of J&K and construction was started in 1970 by Central Hydroelectric Project Control Board under Ministry of Irrigation and Power. In 1978 construction of the projects was entrusted to NHPC on agency basis. After completion of project, it was handed over to NHPC on ownership basis for Operation and Maintenance. Stage-I of the project was commissioned in 1987. First unit of Stage-II of the project was commissioned in 1993, second in 1994 and third in 1995. At the peak of construction, about 12,000 personnel including contractors worked around the clock to complete the project from 1970s to present day, under proper guidance and maintenance of India's most successful company NHPC (NATIONAL HYDROELECTRIC POWER CORPORATION. The project was taken by HCC and various contractors.
  • 4. GENERATOR There are 3 Synchronous generators in stage-1 and 3 in stage -2.The synchronous generators are the alternating generators whose rotor rotate at a a speed called synchronous speed. They run at this speed or not at all. They convert mechanical power into electrical power. Synchronous generators are usually of 3-phase because of several advantages of three phase generation, transmission and distribution. It is also called alternator. It mainly consists of two parts, a stator and a rotor. 1.GENERAL •Manufacturer : BHEL •Place of manufacture : Haridwar •Type of design : Vertical suspension •Applicable Standards : IS:4772-1968 2.Main data •No. of phases : 3 •Rated P.F. : 0.9 lag •Generator continuous rating at : 127.8 MVA Rated frequency and voltage •Generated rated voltage : 11 KV •Rated Frequency : 50 Hz +5% •No. of Poles : 32 •Rated Synchronous speed : 187.5 rpm •Design runaway speed : 375 rpm •Tolerance time of runaway speed : 2 min. •Class of insulation for stator winding : F class •Class of insulation for rotor winding : F class
  • 5. 3.Efficiency •At 100% continuous rated output (MVA) : 98% •At 75% continuous rated output (MVA) : 97.7% •At 50% continuous rated output (MVA) : 97% 4.Temperature •Stator Winding : 60 C •Rotor Winding : 75 C •Max. temp at stator : 150 C •Max temp at rotor : 120 C 5.Excitation Conditions •Field Current : 1365 A •Field Voltage : 243 V •Max. permissible continuous field : 1600 A current •Main exciter rated capacity : 1500 A •Main exciter rated voltage : 243 V •Main exciter ceiling voltage ratio : 1.8 6.Stator •Material : high quality si steel •Insulation of laminations : Varnished •Stator frame construction : fabricated
  • 6. •No. of sectors : 4 •No. of slot : 456 •No. of pole : 32 •No. of slots per phase : 4.75 •Air gap : 25 mm •No. of line terminals : 6 •No. of neutral terminals : 6 7.Generator Rotor •Constructor of field poles : laminated •Method of pole fixing : T-Heads •Rotor rim Construction : punched steel segments •Rotor spider construction : Fabricated •Damper winding construction : cu, short circuited cage type •OD of rotor : 7650 mm •Type of collector ring brushes : carbon •No. of slip rings : 2 8.Generator Shaft •Material of the shaft : Steel forging •OD : 1000mm •Length : 7.9 m •Dia of coupling flange : 1570 mm •No. of coupling holes : 20
  • 7. Transformer 1.General Stage I and Stage II •Manufacturer CG and BHEL •Design OFWF •Applicable Standards IS2026
  • 8. 4.Dimensions Overall length 5.5m Overall width 5.3m Overall height 7.5m 2.Main data •No. of phases : 1 •Rated power : 43.33 MVA •Rated Frequency : 50 Hz •Rated Voltage(No load) HV side : 220/sqrt 3 KV LV side : 11 KV •Rated Line Current HV side : 340.7 A LV side : 3939.1 A •Temperature Rise (oil) : 55 C •Temperature rise (winding) : 65 C •HV winding : star •LV winding : delta 3.Losses •Load losses at rated power, : 45 KW frequency and at principal tapping, referred to winding •Core loss : 180 KW •Total Loss : 185 KW
  • 9. 6.HV neutral bushing Type Oil communicating Current rating 630 A Voltage 36 Kv 7. bushings/bus duct termination Current rating 3150 A Voltage rating 17.5 KV 5.Transformer bushings Manufacturer S&S Bushing ltd. Type Oil filled condenser Current rating 800 A Voltage rating 245 Kv
  • 10. 2.Main data Governor operating oil pressure minimum 31Kg/cm2 maximum 40Kg/cm2 Rated 40Kg/cm2 Minimum wicket gate setting Closing 10 sec Opening 11 sec Adjustmnt range in Governer opening and closing times 3 - 30 sec. Sensitivity of governor to respond to minimumspeed change of rated speed 0.02% Governing system 1.General Manufacturer •Control Unit(Electro) : BHEL •Hydraulic Unit(Hydraulic) : BHEL
  • 11. Turbines The turbine used at salal power plant was the Francis turbine. Francis turbines are most widely used among water turbines and the development of the Francis turbines in the last decade has opened up a large range of new application possibilities for this type. These advances, motivated by a search for maximum profitability, have become possible as the result of improved knowledge of the water flows in turbines and other hydraulic phenomena. A complete investigation and intensive research are carried out and efforts are put forth in the improvement of turbine performance, the selection of suitable materials, and the construction design in consideration of difficulties imposed by mechanical, manufacturing, and maintenance factors at the design stage. TOSHIBA is always making best efforts to design and manufacture highly efficient runners to meet all requirements or Specifications. The runner is designed in consideration of various parameters for computation by both theoretical analysis of internal flow and experimental investigation by model tests. The runner is usually made of carbon steel castings and overlay coating of stainless steel welding will be made on critical areas of cavitations if necessary. For higher head machines, the runner is made of stainless steel castings. Especially 13%a Chrome steel with enriched Nickel content becomes widely used for its excellent anti-cavitations corrosion characteristics and mechanical strength.
  • 12. The hydraulic research of the water passage through the spiral case to stay vanes becomes very important in diminishing the losses of the flow and the angle and the shape of stay vane cascades are carefully designed. A new type of construction (parallel type) advantageous in structural design is applied to all the stay rings. The spiral case is made of steel plates for welded structures or high tensile strength steel plates. TOSHIBA has used 60 or 80 kg/mm' high tensile strength steel plates for spiral case shell plates of a big turbine or a high-head strength turbine. From the view point of field welding, the spiral case shells are accurately cut out by automatic gas-cutting machines, contributing to perfect field assembly even without a temporary shop assembly check.
  • 13. MAIN SHAFT The main shaft for the turbine is made of high grade forged carbon steel. The main shaft is connected to the generator shaft or the intermediate shaft by a flange coupling. The shaft surface passing through the shaft seal is protected with a stainless steel shaft sleeve to prevent the main shaft from wearing. DRAFT TUBE LINER The most commonly employed draft tube is of elbow type, in a concrete structure, fixed with anchoring materials. Overall configuration of the draft tube is thoroughly checked at Toshiba Research Laboratory to ensure effective use of the head energy. The draft tube liner, of welded construction, is made of steel plate for general structure. If necessary due to theoretical and practical reasons, a special air admission system is provided with a draft tube liner to reduce water-pressure pulsation in the draft tube.
  • 14. SPECIFICATION OF TURBINE AT SALAL POWER STATION •Type Vertical Shaft Francis •Rated Speed : 187.5 RPM •Rated Net Head : 94.5 m •Minimum Head : 94.5 m •Maximum Net Head : 102 m •Rated Discharge : 137 Cumecs •Turbine Rated Output At rated head and rated discharge : 117.5 MW Maximum Output of turbine at
  • 15. Head > Maximum Head 123.5 MW Optimum Efficiency of Turbine at 90% Part Load 92.5% Maximum Runaway Speed 375 RPM Specific Speed 229.2 m/KW Direction of Rotation from Top Clock wise Maximum Axial Hydraulic Thrust 382 Tonnes Flywheel Effect of turbine Rotating Parts 13000 Tonnes-m2 Total Thrust from turbine Carried by Generator 382 Tonnes Mass of Turbine rotating parts 52.4 Tonnes Maximum permissible pressure rise 139 m (Max. water hammer) Speed rise at 100% load throw off 55% Pressure rise at 100% load throw off 35%
  • 16. 220KV OUT DOOR SWITCHYARD: Equipment in the switchyard •Circuit breakers •Isolators •Current transformer •Potential transformer •Capacitive voltage transformer • Lightening arrestor •Bus Bar & conductor •Earth switch •Wave trap •Insulators (post & Suspension) •Control & power cables •Clamps •Fire fighting equipments
  • 17. SINGLE LINE DIAGRAM OF 220 KV SWITCHYARD OF SALAL POWER STATION Circuit Breaker Isolator C.T. P.T. L.A. Capacitive Voltage Transformer Earthing UNIT#3UNIT#1 UNIT#2 BUS-A BUS-B UNIT#5UNIT#4 UNIT#6 BUS-A BUS-A P.T. BUS-B P.T. K-2 J-2K-1 K-3 K-4 J-1 Wave Trap
  • 18. 1.Circuit breakers In this switchyard mainly two types of circuit breakers were used, one is SF6 and another one is MOCB. SF6 breakers in Unit# 4,5,6 and outgoing feeders Kishanpur # 2, Jammu #1,2. The MOCB is used in Unit # 1,2,3, Bus coupler and Kishanpur # 1,3,4 feeders SF6 CIRCUIT BREAKER SF6 GAS: gas in pure state is inert, exhibits exceptional, thermal stability and has excellent arc quenching property as well as exceptional high insulating properties. It is one of most stable compounds, inert, non-flammable, and non- toxic and odorless. The density of gas is about 5 times that of air and heat dissipation in it is also much more than in air. At atmospheric pressure the dielectric strength is about 2.4 times that of air and at 3Kg/cm2 it is same as that of oil. PHYSICAL PROPERTIES OF SF6 GAS Molecular weight : 146.07 Melting point : - 50.7 Dielectric constant : 1.002 (at 760mm of Hg pressure) CONSTRUCTION: This is single-phase auto reclosing type circuit breaker. The three phases have their own mechanism and air reservoir inter connected electrically and pneumatically. Single pole of the breaker consisting of interrupting unit, supporting unit and mechanism housing. INTERRUPTING UNIT: The interrupter is a single-phase puffer type, which consists of puffer cylinder and piston, stationary contact and its assembly. Over conductors are connected to the upper and lower terminal pads.
  • 19. OPENING OPERATION: opening is affected by pulling down the insulating rod, piston rod, puffer cylinder, moving contact, moving arc contact and the nozzle. After some contact wiping the stationary and moving arc contacts separate there by generating arc. During down ward movement the gas pressure in puffer cylinder builds up and high- pressure gas flows through nozzle and quenches the arc CLOSING OPERATION: in closing operation insulating rod is pushed up and all the parts move in reverse order of opening operation. Also sf6 is gas taken in to the puffer cylinder. SUPPORT UNIT ASSEMBLY: It consists of support porcelain and insulating pull rod, this provides insulation between live parts and ground SF6 gas filled in containers in interrupting and supporting unit at rated pressure. AIR SYSTEM: Compressed air is required for opening operation of the breaker. It is stored in inter connected chamber 70 Lt each which act as local source. This system is provided with motor compressor unit. The capacity of compressor is 90 L/M. This governor switch compressor system maintains the pressure between 14.5 to 15.5 Kg/cm2 PNEUMATIC OPERATING MECHANISM: The pneumatic operating mechanism consists of opening piston, air cylinder, control valve, tripping coil& closing coil, latch, trigger, closing spring, shock absorber and others. OPENING OPERATION: The opening operation is affected by compressor air, when opening signal energies trip coil, latch and cam are released by trip coil plunger and control valve is open by spring which allows the compressed air, to push down the piston of the pneumatic operating mechanism. The movement of opening piston is transmitted to the puffer cylinder through livers and rods and moving contacts of all all three poles are pulled down together. The movement of opening piston
  • 20. compresses the closing spring. At the final position of the opening operation the control valve is closed by the linkage and the air in the cylinder is exhausted through the control valve to the out side atmosphere. The piston is held in opening position against forcing of the closing spring by holding latch. CLOSING OPERATION: Closing operation made by the closing spring. When closing signal energies the closing coil trigger and holding latch released by the closing coil plunger, and closing spring closes the breaker. SPECIFICATIONS Rated voltage : 245 KV Rated insulation level : 1050 KV (peak) Rated frequency : 50 HZ Rated normal current : 3150 A Rated short circuit breaking current : 40 KA Rated short circuit making current : 100 KA Rated break time : 60 ms (3 cycles) Rated short time current : 40 KA for 3 sec Operating mechanism : spring closing, pneumatic tripping Operating pressure(air) :15 kg/cm2 SF6 gas pressure :6kg/cm2 Opening time : 30ms Closing time : 100ms Pole discrepancy : 3.3ms Make : CGL
  • 21. SF6 Circuit Breaker
  • 22. MOCB (MINIMUM OIL CIRCUIT BREAKER) 220KV MOCB having two breaking units per pole, normally this can vary between one and four, depending on the, rated voltage, insulation level and short circuit current breaking capacity. The double breaking unit per pole is connected together to form V shaped breaking unit. The breaking units are mounted on post insulator, which constitute the insulation of the pole to earth. Each [post insulator supports one double breaking unit. The post insulator erected on a low concrete pedestal. The breaking unit consists of an oil container with an arc control device of cross blast type. The oil container consists of a porcelain tube reinforced with a glass fiber tube on the inside, fixed contact mechanism housing cast in light metal and gas tight top cap. The breaking unit is hermetically sealed and pressurized with N2 gas. The top cap is, therefore fitted with a pressure control valve. The circuit breaker is operated with a motor operated spring – closing device of the type BLG. The operating device is connected with mechanism of the breaking units via a pull rod system, link gears and operating insulators. The circuit is closed by operating device, which contains the closing spring. When closing, the opening springs, which are tightly joined, to the outer end of the rod system are charged. The opening catch in the operating device keeps the CB in the closed position for opening all that is required is to release the opening latch. Each breaking unit contains 53 lt.
  • 23. MOCB SPECICATIONS: Type : HLR 245/2502 E Rated voltage :245 Kv Impulse with stand voltage : 1050 Kv Rated normal current : 2500A Rated short time current : 40 KA Breaking capacity : 40 KA Rated making current :100KA Gas pressure : 0.3 to 0.7 Mpa Make : BHEL MOCB Circuit Breaker
  • 24. 2.Isolators •Make : AMEI/WSI/BIMCO •Type : Triple pole single circuit Breaker •Standard : IS9921 •Rated Continuous Current : 1600 A •Rated voltage : 245 KV •No of operations possible : 2500 •Rated short time current(1 sec) : 40 kA •Clearance (Live and Ground) : 2300 mm •Clearance(phase to phase) : 4500 mm •Clearance(fixed contact and blades) : 2700 mm 3.Current transformer Current transformers are instrument transformers to measure current in high circuit and for protection purpose. The current transformer connected always in series with line. The CT s installed in switchyard is oil filled hairpin type of 220kv. The hair pin arises out of fact that the HV primary winding is of that shape, comprising a tube having graded insulation of oil impregnated in which metal foils are inter posed at sutiblr intervals. The outer most of these coils is connected to earth via an insulated terminal and link enabling dielectric loss angle measurements be taken to check up the quality of insulation. This foil further acts as earth shield between primary and secondary winding. The secondary winding with own cores are mounted over the legs of hairpin. In this type of design up to 4 secondary cores can be accommodated, an alternative design allowing accomadation forf ive secondaries.
  • 25. Each unit is completely oil filled and sealed to ensure that the oil cannot come in to contact the atmosphere and hermetically sealed with N2 gas at 0.35 kg/cm2 The flexible oil reservoir in the top housing above the high voltage terminal chamber ensure this by preventing the creation of undue pressure or depressions. Unit side CTs having 4 core and outgoing feeder CTs having 5 core. Unit CTs core 1 is for link line protection, core 2 is for LBB protection, core 3 is for Bus differential main zone protection and core 4 is for metering, Bus differential check zone protection. Ratio is 800/600/400/: 1. The feeder side CTs core 1 is for main 1 distance protection and fault locator, core 2 is for main 2 distance protection and disturbance recorder, core 3 is for Bus bar main zone protection, core 4 is for Bus bar check zone protection and core 5 is for LBB protection and metering. CTs ratio is 800: 1, make BHEL and CGL.
  • 26. Current transformer 4.VOLTAGE TRANSFORMER Voltage transformer is an instrument transformer for high voltage measurement and protection purpose. In this switch yard, two types of voltage transformers are used. For Bus Bar potential transformer and for out going feeders capacitive voltage transformer. The Bus bar voltage transformer having one primary and two secondary winding. The primary winding is connected across phase and earth through neutral link. The secondary winding is for measureme
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