课件参考分析1acfc

AFirstDOC.PYX17GPA003DDS045GNSYSTEMDESIGNCHAPTER3GENERALPKX17GPA003GDS045GNA:B:√C:Issued GEDI省电ThisisthepropertyofGEDI.Itmustnotbeused,reproduced,transmittedordisclosedwithoutthepriorwrittenpermissionofGEDI.本文件之属于省电力。未获我院，任何人不得擅自使用、、传递或该文件。MODIFICATIONS/REVISIONMODIFYAFIRSTDesignofProtectionProtectionofthegeneratingunitandpowertransmissionfollowsthephilosophywherebynosinglefailureofprotectivedeviceorsystemsshallcauseatriporpermitafaulttoremainconnectedtothesystem.Wheresuchasinglefailureeventispossiblethedevicesandsystemshavebuilt-inredundancy.Controlofthefollowactuatorsis Generatorcircuit500kVcircuitReduceoutputtopre-setTheserequirementsaremetbytheprovisionoftwoindependent puterprotectivesystemschannel1andchannel2,usinghighreliabilityrelayswhichhavetheiroutputcontactsselectivelyallocatedtotwoentirelyindependenttripsystemswithseparateDCs,andusetheprincipleof“energizetotrip”.Themainandback-upprotectionequipmentsareconfiguredredundant,andthenon-electricprotectionisDuetospacelimitationsandprovenreliability,duplicationofcurrenttransformersisnotconsiderednecessaryforthegenerator/transformerprotection.Theprotectiverelaysystemisprovidedwithin-builtmanualtestfacilitiestoallowsecondaryinjectiontestswithoutdisturbingthewiringandtripsystem.Thefacilitiesassociatedwiththetripsystemsarephysicallysegregatedasfaraspracticable,bytheprovisionofseparaterelaybays,separateterminalblocksinmarshallingcubiclesanddiverseroutingofsecondarycables.SupplysupervisionisprovidedforpowerstoallprotectionTheredundantmainandback-upprotectionequipmentsarerespectivelyinchannel1&2,andthenon-electricprotectionisinchannel3.Theyarelistedasbelow(toberenewedaccordingtolatestrequirement):RefertoACsinglelinediagramforGenerator/TransformerProtection: Channel1&2ProtectiveChannel3Protective1Maintransformer2Main 3GeneratorlossofexcitationMaintransformerpressureadvance4GeneratorReversepowerMaintransformerwindingtemperaturehig（261）5Generator90%statorearthfaultMaintransformeroiltemperature6Generator100%statorearthfaultMaintransformeroilposition7GeneratorstatorMaintransformercooler8Generatornegativephasesequence9MaintransformerzerosequencedifferentialStepdowntransformerAonloadtapchangerMaintransformerzerosequenceovercurrentMaintransformerHVbackupovercurrentStepdowntransformerAwindingtemperatureGeneratorpoleslipStepdowntransformerAoiltemperatureGeneratorunderfrequencyStepdowntransformerAoilpositionGeneratoroverfrequencyStepdowntransformerAcoolerStepdowntransformerBMaintransformeroverfluxing(runincaseofDLStepdowntransformerBonloadtapchangerGeneratorStepdowntransformerBpressureStepdowntransformerBwindingtemperatureChannel1&2ProtectiveChannel3ProtectiveStepdowntransformerBoiltemperatureMaintransformerventilatorStepdowntransformerBoilpositionGeneratorcomplexvoltagecontrolledStepdowntransformerBcoolerExcitationsystemGeneratorC.B.tripGeneratorstatorlossofVT24kVbusbarearthGeneratorturbineGeneratorLBAlossofRCPspeedlowleadtoStepdowntransformerAStepdowntransformerAtapchangeroilpositionStepdowntransformerA24kVvoltagecontrolledStepdowntransformerBtapchangeroilpositionStepdowntransformerAbranchAovercurrent(InExciterwindingearthStepdowntransformerAbranchD(InStepdowntransformerBStepdowntransformerB24kVvoltagecontrolledStepdowntransformerBbranchEChannel1&2ProtectiveChannel3Protective(InStepdowntransformerBbranchF(InStepdowntransformerAventilatorStepdowntransformerBventilator AOverload On-LoadVoltageregulation On-LoadVoltageregulationShortlineopticalNB：TheprotectivefunctionsofeachsetarearrangedtooperatorintwotripwindingsoftheUnitTripThelogicdiagramforsystemGPAisshownondrawingPYX/17GPA/016/DDS0/45/DD,whichdepictsthetriparrangementforeachunit.Particularitemsofntwhichrequireatripsignalonaunittrip EHVcircuitStepdowntransformerbranchThetripoftheseactuatorsitemsisachievedinsomecasesbyelectricalmethodandinothersbymechanical/hydraulicmethods.ProcesstripreversepowerAccordingtoGPAsystemtriplogic,tripsaregroupedbydifferentprotectionitems.Forsomeexceptionaloperationcondition,generatorshutdownisnotimmediateafterprotectionisacted,butoutputviaprocesstrip.Whileprocesstrip:1st-closingturbine valves,2nd-reversepowerrelayaction,3rd-tripGeneratorC.Bandrestrainexcitation.Protectionactivatedviaprocesstripreversepowerinterlockbaseonfollowingprinciple:insomecasethat valvesarenotcompleyclosedafterachievetheorder，generatorisnotrunningasamotor,G.C.Bistrippedcausebyinterlockcontactsofturbine valvesorprotectioncontactsorsoundandlightindicationof valvesclosed”whichmakesoperatortripsgeneratorcircuitbreakerbymisoperation,althoughinputislittleatthemoment,however,circuitbreakeristrippedwhichmightcausegeneratoroverspeedorflyProtectionactivatedviaprocesstripreversepowerinterlockcouldpreventthecaseupward,i.e.thetripG.C.Bwillnottakeceuntilreversepoweruptoapre-setThesetpointoflockoutelementonreversepowerrelayusedforprocesstripis(1~3)%Pgn,G.C.Bandexcitationbreakerwillbetrippedat1.0~1.5sdelayvialockoutofturbinestreamvalvecontact.Inviewoftheneedtopreventturbineoverspeed,thefollowingelectricalprotectionsoperatedviaprocesstripGeneratorlossofGeneratorstatoroverload（reversetimelimit；EHVCircuitThefollowingprotectionsonlytripEHVC.B.leavingthegeneratorcircuitbreakerclosed,thuscingtheunitinto“houseload”operation(tripto“houseload”).Maintransformerzerosequenceovercurrent（t1timelimitGeneratorunderfrequency(inLGAorLGD)（t1timelimitMaintransformeroverfluxing(runincaseofDLopen)(t2timelimit；Generatornegativephasesequenceoverload（t2timelimit；limit；GeneratorelectricalTheprotectionarrangementforthegeneratoristomakesurethatthemainconnectionsatthegeneratorterminalvoltagelevelandgeneratoroperatingsafely.StatorPhasetoPhaseTheprotectionofthestatoragainstphasefaultsisprovidedbythegeneratordifferentialThisprotectionismetbytheprovisiondifferentialschemeforahighspeedoperationandtransientInordertokeepdamagetostatorwindingsandcorestoaminimumthemethodofearthingisbyadistributiontransformerloadedbyaresistortolimitthegeneratorneutralfaultcurrentto10amperesatnominalstatorvoltage.Fortotalprotectionofthestatorwindings,statorearthfaultprotectionwithrangeof90%and100%areHighsensibilityprotectionforzerosequence50Hzvoltageprovidesaprotectiverangeof90%~95%tostatorwinding,protectiverelayadoptsaveryhighratiocircuittofilterthethirdharmonicvoltageandonlyfundamental20Hzvoltageinjection100%earthingprotection.Thisprotectionisstatorwindingsingleearthingprotectionwithexternalelectricalsupply，injecting20HZlowfrequencyalternatingsignalintogeneratorstatorwindingviageneratorneutralearthingtransformer，whichcandetecttotallyearthingfaultfromgeneratorneutraltomaintransformerLVside，providingwholesupervisionfromrest&starttooperationforunit,ithasnothingtodowithoperationconditionandactive&reactiveoutput,whichtrulyrealize100%statorearthingprotection.GeneratorBack-upIfmainprotectionorassociatedcircuitbreakersdon’tbehaveforsomeparticularreasonsincaseofgeneratorandelementsneargeneratorareshortcircuited,thefollowingback-upprotectionisneededwithrestrictselectivityforGeneratorcomplexvoltagecontrolledAcomplexvoltagecontrolledovercurrentprotectionprovidesback-upprotectionforthegenerator,transformer,busbarandline.Thesetpointvalueisdesignedtooperatewithloadcharacteristicsdowntoapre-selectedvoltageandtooperatewithafaultcharacteristicbelowthatThephaseangleofthevoltageappliedtotheprotectionhastobeshiftedsothattheyareinphasewiththesystemvoltagesinorderfortherelaytoseesystemfaultscorrectly.Thisphaseshiftis plishedbygeneratorprotectionGeneratorrotorearthGeneratorfieldcircuitsarenotearthedandthereforeasingleearthfaultinitselfisnotdangerous.Howeveritspresenceincreasestheriskoffurtherearthfaultsduetotheincreasedvoltagestressbetweenearthandtheotherpartsofthewindingswhenrotorvoltageareinducedbystatortransients.Adoubleearthfaultwilleventuallyresultinthepartofthewindingwhichisshortcircuitedandmaycauseseriousorpermanentdamage.ThegeneratorrotorearthfaultprotectionofthisprojectisdbyT-Gcontractor,andislocatedintheexcitationsystemcubicle.Inordertolimitthedamage,therotorearthfaultprotectionintheexcitationsystemcubicleoperatorwhenthereisrotorearthfaultandoutputthesignaltotheGPAsystemforalarmorprocesstrip.GeneratornegativephasesequenceWhenasymmetricshortcircuitorunbalanced3-phaseloadoccurs,thereisnegativesequencecurrentthroughgeneratorstatorwindingsandmagnetfieldwithaspeedtwiceastherotorsynchronousspeed,thusdouble-frequencycurrentisformedintherotor.Generatorhasacapacityofwithstandingalimitednegativesequencecurrent,withinwhichtherewouldbenodamagetorotor,therefore,thecapacityofwithstandingthenegativesequencecurrentisthebasisoftherelayprotectionanditssettingsTheprotectionactingvalueisassociatedtonegativephasesequencecurrentofgeneratorneutral-end.Theprotectionaction：t1—alarm；t2—triptohouseload.GeneratorlossofAfterlossofexcitation,generatorrunsasynchronously,rotorbringslip,currentofstatorriseswhileitsvoltagedrops,activepowerdrop,reactivepowerincreasesanddirectionreversely,differencefrequencycurrentappearsinrotorcircuit.ThevarietyofelectricaldataupwardswilldamagestabilityofpowersystemandsafetyofgeneratorinsomeFortheoutputofthisprotection,ifvoltageofbusbarislowerthanthepermittedvalueafterlossofexcitation,protectionoperatestoprocesstripatatimedelay;whilevoltageofbusbariswithinthepermittedvalueafterlossofexcitation,generatoroutputpowerwillbereducedautomatically.Protectivecriterionforlossofexcitationismainlyconsistedofstatorcriterionbaseonadmittancemeasurementprinciple,themethodofadmittancemeasurementphysicallysimilartostabilitylimitofgenerator,whichhasnothingtodowithdeviationofgeneratorterminalvoltagecomparedwithratingvoltage,thetripcharacteristicofprotectionapparatuscaneasilyapproachstabilitycharacteristicofgenerator.GeneratorPolePoleslipprotectionhasbeenprovided,sincepoleslipcanLargefluctuationsinvoltageandfrequencyatthegeneratorterminalswilleffectthestationauxiliarypowerLargefluctuationsinvoltageandalesserextentfluctuationsinfrequencyofRapidfluctuationsingeneratorspeedduringpoleslipreflectinginthe demandfromthereactor,possiblyresultinginlossofcontrol.InternaldamagetogeneratorduetooverheatingormechanicalFlowofsynchronizingpowertoandfromthepoleslipgeneratorwhichmayresultinindiscriminateoperationofcertaintransmissionprotection,leadingcascadetripofcircuitsandfurtherinstabilityanddisconnectionofs.Inthecaseofshortcircuitfault,systemsteadyvibratingandPTfault,theprotectivefunctionsshallnotbeSincetheresponseofthegenerationandtransmissionsystemswillbeuncertainunderpoleslipconditions,andtherapidre-synchronizingofapoleslipgeneratorisunlikely.PoleslipprotectionisarrangedtotriptheEHVcircuitbreakeronly,leavingtheGeneratorCircuitBreakerClosedthus“leavingtheunittohouseload”.GeneratorReverseTheeffectofprimemoverfailureistocausethegeneratorto“Motor”bytakingpowerfromthesystemandtheresultmaybemechanicaldamage.Asensitivedirectionalpowerrelayisemployedtodetectpowerreversalsdueto“motoring”,andtopreventoperationwhenthemachineisbeingsynchronized,adefinitetimedelayhasbeenconsiderednecessarytobeincluded.Generatorunderfrequency(inLGAorLGD)Underfrequencyprotectionhasbeenprovidedinordertoprotectstationauxiliariesbyonlyallowingthefrequencydeviationofoneauxiliariesvoltagetokeepwithinsetlimits.Theprotectionisdesignedwithtwostages.The1ststagecausestriptohouseloadoftheunit,the2ndstagecausesaunittripafterafurthertimedelay.GeneratorunderfrequencyTheallowablevibratingrangeis48.5Hz~50.5Hzduringtheturbinenormaloperation.Incaseoffrequencylowerthan48.5Hz,therequirementofturbine-generatorandgridsystemshallbetakenintoaccounttodeterminethetotallimitedrunningtimeandthelimitedlastingperiodeachtimeforturbine-generatorunit.TheprotectioncausesalarmandhasadisyoftotalGeneratoroverOverfrequencyprotectionhasbeenprovidedinordertopreventanoverspeedturbinetrip.Thefaultresultsintheturbinebladevibration.Theprotectionisdesignedwithonestagewhichtripstohouseloadoftheunit.GeneratorUndervoltageprotectionhasbeenprovidedinordertoprotectstationauxiliarysupplytokeepwithinsetlimits.Theprotectionisdesignedwithtwostages.The1ststagecausestriptohouseloadoftheunit,the2ndstagecausesaunittripafterafurthertimedelay.Theprotectionislocatedinthe6.6kVswitchboards（LGA-GeneratorDuringrunuporshutdownofthegenerator,thespeedandfrequencywillbereducedduetothefailureofthevoltageproportionaltofrequencycontrolloop,andoverfluxingcouldoccuriftheAERwanttomaintaintheratedvoltage.ThiscontrolmodeisprovidedasanintegralpartoftheAER,andoperateswhichevertheAERisonmanualorautomatic.Thetwoactionsarefollowed:GeneratorC.B.isopen：restrainexcitation,closing GeneratorC.B.isclosed：tripDL,restrainexcitation,closing GeneratorstatorGeneratorstatoroverloadprotectionisconfiguredtopreventgeneratorfrombeingdamagedduetostatoroverload.Generatorstatoroverloadprotectioncomprisestwoparts:definitetimepartandinversetimepart.Definitetime:protectionissetinsuchaconditionthatitisnotactivatedwhengeneratorrunsatloadcurrentinalongperiod,andprotectionbehavescausesignals.Protectioncanalsoreduceloadautomaticallyifpossible.Inversetime:protectioncharacteristicsissetaccordingtotheoverloadenduringabilityofgeneratorstatorwhichcauseoff-line.GeneratorvoltageadvanceGeneratorwouldbeasynchronouslystartupasathreephasesrapidvoltageisaddedwhenG.C.B.ismisoperated“close”duringbarring,protectionisprovided.G.C.B.shallbeopenwhenthisprotectionacting.IfG.C.B.doesn’ttrip,tripfailureprotectionshallbeactedandtripsallassociatedpowercircuitbreaker.Whengeneratorisnotrunning,theprotectionshallbekeptinoperating.GeneratorLBAlossofThesignalsofGeneratorLBAlossofvoltcollectedbyGPAinclude3independentdigitalsignalsabout88Vwhenmorethan2signalsact,theprotectionactaftera2secondsdelay.GeneratorC.B.tripWhenprotectionoperatedtogeneratorcircuitbreaker,itshallbeopen.Ifthebreakerdoesn’ttrip,theGeneratorC.B.tripfailureprotectionshallactimmediay.ThisprotectionhasbeenarrangedtotriptheunitandEHVGeneratorturbineGeneratorstatorProtectionisprovidedagainstabnormalstatorovervoltage.Thevalueofthegeneratorstatorovervoltageisdeterminedbythestatorwindinginsulation.ThisprotectionhasbeenarrangedtotripDL,restrainexcitation,turbineload-rejection.MainTransformerandStepDownTransformersPhasetophasefaultprotectionoftheMainTransformerandStepDownTransformersisprovidedbydifferentialprotection.Thedifferentialprotectionisprovidedwithloadbiasto etheeffectoftapchangingandcurrenttransformermismatchandharmonicrestraintsoastoensurestabilityformagnetizinginrushcurrentsfollowingtheclearanceofacloseupexternalfault,andonswitch-in.SeparatezerosequencedifferentialprotectionoftheMainTransformerHVwindingisnecessary,sincethepercentageofthewindingprotectedbythedifferentialprotectionislimited.ZerosequencedifferentialprotectiongivesgreaterHVwindingcoverage.EarthfaultprotectionoftheLVwindingsandconnectionsisincludedinthestatorearthfaultZerosequencecurrentdifferentialprotectionandzerosequenceovercurrentprotectionareprovidedforthemaintransformer.Thezerosequenceovercurrentprotectionisdesignedwithtwostages.EarthfaultprotectionoftheHVwindingsoftheStepDownTransformersisincludedinthe24kVbusbarearthfaultprotectionassociatedwiththeStepDownTransformerNeutralEarthingEquipment.MainTransformerinversetimeOvercurrentInversetimeovercurrentprotectionisprovidedasaback-upprotectionagainstsystemfedfaultstoageneratorcircuitfault,notclearedbythemainprotection,andtoclearfaultsofhighfaultleveloccurringatornearthemaintransformerHVbushings.Thisprotectionhasbeenarrangedtotriptheunit.LowvoltagecontrolledovercurrentprotectionisprovidedontheHVsideofeachStepDownTransformerstoprovideback-upprotectionforallHVandLVwindingfaults.Asthisprotectionhastogradewiththe6.6kVinterconnectorprotectiontheoperatingtimesforHVterminalfaultsarequitelong.Thisprotectionhasbeenarrangedtotriptheunit.Overfluxingoccurswherethetransformervoltageandfrequencyarevaryingandnotkeptinproportiontooneanother.DuringrunuporrundownconditionitispossibleforeitherafailureofbothAERchannelsinautomaticcontrolorincorrectoperationwhilstundermanualcontrol,tocauseoverfluxingoftheMainTransformerandStepdownTransformers.OverfluxingprotectionarethereforeprovidedforprotectionoftheMainTransformerinallmodesofexcitationcontrolandwhentheGeneratorCircuitBreakerisopen.Protectionoperatestripon500kVsidecircuitbreaker.WhentheGeneratorCircuitBreakerisclose,theprotectionofthetransformeriscarriedoutbythegeneratoroverfluxing(24G).Stepdowntransformerbranchovercurrent(InLGA001TB\LGD001TB\LGE001TB\LGF001TB)Thisprotectionhasbeenarrangedtotripstepdowntransformerbranchbreaker.MainandStepdowntransformerbuchholzandpressurehighThesesignalswereofferedbyGEV.ThisprotectionhasbeenarrangedtotriptheMainandStepdowntransformerwindingandoiltemperaturehighThesesignalswereofferedbyGEV.Thesignals“Windingtemperaturehigh”and“oiltemperature”initiateeachonecategory2alarminThesignal“windingtemperaturehigh-high”andthesignal“oiltemperaturehigh-high”willinitiateacategory1alarminKIC(faultthatisnotautomaticallyhandledandrequiresimmediateactionbytheoperator).Accordingtoinvestigationsmadeafterthe1ststageandtothewrittenprocedurestheoperatormustactinordertorectifytheexcessoftemperaturesituation.TripEachprotectivefunctiontripsasthefollowingtrip[1]TriptheunitIGeneratorC.B.tripEHVC.Btripstepdowntransformerbranch6kVbreaker,restrainexcitation、closingturbine [2]、TriptheunitII：tripGeneratorC.B、restrainexcitation、closing valves[3]、Offlineandrestrainexcitation：tripGeneratorC.B、restrainexcitation、turbineload-rejection[4]、Offline：tripGeneratorC.B、turbineload-rejection[6]、processtrip：1st-closingturbine valves,2nd-reversepowerrelayaction,3rd-tripGeneratorC.Bandrestrainexcitation；[8]、Stepdowntransformerbranchbreakertrip：tripstepdowntransformerLVbranch AlarmAfteranyprotectionaction,alarmsignalsshallbeexported.Thefollowingprotectiononlyexportsthealarmsignalswithoutanytripaction.VTMainandStepdowntransformerwindingandoiltemperaturehigh、oilpositionabnormal、pressureMainandStepdowntransformercoolerWhenVTsupervisionprotectionactstheassociatedprotectivefunctionshallbeinterlockedavoidingChannel1(2)ProtectiveChannel3Protective11Maintransformer2Maintransformerdifferential2Maintransformer3Generatorlossof3Maintransformerpressure4GeneratorReversepower4Maintransformerwinding5Generator90%statorearthfault(64G1)5Maintransformeroiltemperature6Generator100%statorearthfault(64G2)67Generatorstator7Maintransformercooler8 sequence8StepdowntransformerA9 sequencedifferential(87N)9OnloadtapchangerA sequenceovercurrent(51N)StepdowntransformerApressureMaintransformerHVbackupovercurrent(51)StepdowntransformerAtemperatureGeneratorpoleslip temperature StepdowntransformerAoilposition StepdowntransformerAcooler7Channel1(2)ProtectiveChannel3ProtectiveGenerator3,7(DLStepdowntransformerBMaintransformeroverfluxing(runincaseofDLopen)（24T）t1(4s):7;OnloadtapchangerBGeneratorStepdowntransformerBpressureGeneratorundervoltage（inLGAswitchboard）（27）t2(4s):StepdowntransformerBwindingtemperaturehigh（26TB1）Generatorstart-stop temperature StepdowntransformerBoilposition controlledStepdowntransformerBcooler7 ExcitationsystemGeneratorC.B.tripGeneratorstatorlossofVTEHV-CBtripfailure(inbreaker24kVbusbarearth7GeneratorrotorearthGeneratorturbineGeneratorLBAlossofRCPspeedlowleadto StepdowntransformerAtapchangeroilpositionabnormalStepdowntransformerA24kVvoltagecontrolledStepdowntransformerBtapchangeroilpositionabnormal Exciterwindingearth branchDovercurrent(In StepdowntransformerB24kVvoltagecontrolledChannel1(2)ProtectiveChannel3Protective branchEovercurrent(In branchFovercurrent(In ventilatorprotection ventilatorprotectionUnderfrequency(In VoltageStepdowntransformerBOverloadinterlockOn-LoadVoltageregulationShortlineopticalHouseloadWhenEHVC.B.isopen,thegeneratoronlyservesthehouseloadoftheunit.Theunitseparatedfromthesystem,andgeneratorcircuitbreakerisclosed.ThefollowingprotectionsinvolvedinthisrunningmodeNegativephasesequenceoverload(2stage)Maintransformerzerosequenceovercurrent（t1timelimit）GeneratorpoleslipGeneratoroverfrequencylimit；DesignofCurrentForthecalculationofthekneepointvoltageandratedoutputs