COMBINATION OF TWO CYCLES GAS CYCLE STEAM CYCLE TWO GAS TURBINES ONE STEAM TURBINE TWO HRSG SYSTEMS MORE EFFICIENT ECO FRIENDLY NO WASTAGE
PRINCIPLE: In a combined cycle power plant, a gas turbine generator generateselectricity and the heat in the gas turbine’s exhaust gases is used to generatesteam in a Heat Recovery Steam Generator that in turns used to generateelectricity with steam turbine generator which enhances the efficiency inpower generation.
PRINCIPLE DOMINANT ROLE CONSISTS OF STATOR AND ROTOR NEED OF PROTECTION GAS TURBINE GENERATOR(GTG) STEAM TURBINE GENERATOR(STG) RATINGS GTG STGRATED VOLTAGE 15.75 KV 11KVRATED CURRENT 7698 A 12543 APOWERFACTOR 0.8 0.8COOLING TYPE WATER WATER
ROTOR: ROTATORY PART IN THE MACHINERY SPECIFIED DETAILS OF ROTOR Diameter of body 1050 mm No. Of wound slots per half pole 8 Conductor material CuAgSTATOR : Supports armature core with laminations. SPECIFIED DETAILS OF STATOR: Core length 4620mm Inside diameter of core 1150mm No. of slots 60
During fault and abnormal conditions Generator Differential Protection. Loss of excitation Overvoltage Protection Earth fault protection Negative Sequence Protection Over current/Under voltage Protection. 95% Stator Earth Fault protection Reverse Power protectionCooling system: CACW means circulating air circulating water. For circulation of the air two fans are mounted on both ends of the generator rotor.
PRINCIPLE -ELECTROMAGNETIC INDUCTION MAGNETICAL COUPLING DESIRED VOLTAGE LEVELS FOR MACHINERY
Description unitsNo. of phases 3Rated power 210MVANo. of windings per phase 2Rated Voltage(no load) onH.V side 400KVRated Voltage(no load) onL.V side 15.75KvRated Current on H.V side 303.7ARated Current on L.V side 7707.1ARated frequency 50Hz
TYPES OF TRANSFORMERS step-up transformer step-down transformer current transformer potential transformer ideal transformerCooling system Oil Forced Air Forced unit Five units coolers each having 25% cooling capacity 4 working and 1 standby with selective switchingProtection system Differential Protection Buchhlolz Relay Over current Earth Fault Protection
Mv system: Bus-duct of GT generator via station service transformer with 6.6kv low resistance earthed system Vaccum circuit breaker(VCB) Microprocessor based protection systemLv system : Rating up to maximum 250 KW, including the UPS system, chargers & batteries. Automatic dead-bus changeover motors rated 160-250 KW CB are provided motors rated < 160 KW, contactor-controlled feeders
ONE AND HALF BREAKER SWITCHING SCHEME 400 KV SWITCHYARD STARTUP POWER SUPPLY FOR BACK CHARGING
INTERCONNECTION PURPOSELoads and source of electrical power systemsGenerators and main transformerTypes of bus bars according to voltagesVoltage levels Bus barsLow RigidMedium Rigid, insulated phase,sf6High Rigid,strain,sf6
CIRCUIT BREAKERSSF6 CIRCUIT BREAKERRated voltage 420vNormal current 2000A ISOLATORSEARTH SWITCHOperating Mechanism ManualControl 220V DC SURGING ARRESTORS LIGHTNING ARRESTORS
BREAKER CONTROL Line bay breaker Steam Turbine Generator Transformer Bay Gas Turbine Generator Transformer Bay Local Control Remote Terminal Unit A RTU has been envisaged for facilitating the data transmission such as MW, MVAr, MWH and MVArH of each line to the Remote Load Dispatch Center through the Microwave Links, as planned and will be supplied by AP Transco. In addition, the RTU will be able to collect and communicate the switchyard status and data to SCADA system which will be supplied by APTransco. The RTU will be located in the switchyard control room.
1 Line bays protection Main I protection Main II protection Generator Transformer bays Common Protections: For all the bays, following additional protections and relays will be provided. ◦ Local breaker backup protection (LBB) ◦ Trip Circuit Supervision for each trip coil ◦ DC supply supervision ◦ Pole discrepancy protection ◦ Anti pumping device for breaker closing ◦ All auxiliary relay as per system requirement
STANDBY DIESEL GENERATORThe standby diesel generator is connected to the LV switchgear. The diesel generator is arated 625 KVA in order to feed the essential auxiliaries for the safe shut down of the plantin the event of loss of normal AC power. This is used to charge the station batteries. Thestandby diesel generator set is automatically started upon detection of loss of normal ACpower
PARTS OF DIESEL GENERATORGenerator ControllerFuel TankAutomatic Voltage RegulatorTYPES OF DIESEL GENERATORSThe TS25 Baldor Standby GeneratorThe 10,000 Watt Aurora Standby Generator
DC&UPS SYSTEM220V DC SYSTEMS:-Each DC system consists of battery and battery charger, and associated D.C. distributionboards. The whole battery system is sized for one (1) hour ST shut down operation. The safeshutdown is carried out bye the DC system in conjunction with the standby diesel generatorset. For meeting this 2*50% battery banks of lead acid tubular type are provided .
UPS:-240V AC uninterruptible power supply is provided bye two inverters with automatic staticchangeover switches. During normal operation the UPS is supplied through the invertersand the chargers which are connected to the respective low voltage switchgear.
Here overall view of the combined cycle power plant suggests the best generation of power and gives better efficiency by using the gas and steam cycles Electrical equipments such as gengrators,transformers,circuit breakers, isolators and most of the equipments been observed and their workings has been observed. Finally there is a far distance between the practical scenario and the bookish knowledge and we linked between the both conditions.