Dynamic Testing of Generator Protection Using a Mo

DynamicTestingofGeneratorProtectionUsingaModelGeneratorPlatformGER-400456thGeorgiaTechProtectiveRelayingConferenceAtlanta,GA,May1-3,2002DYNAMICTESTINGOFGENE[e-mail](905)[e-mail](610)[e-mail](905)2012199GEPowerManagement215AndersonAvenueMarkham,OntarioCanadaL6E1B3DynamicTestingofGeneratorProtectionUsingaModelGeneratorPlatformPage2of181.IntroductionModern,microprocessor-basedgeneratorprotectionrelaysintegratemanyfunctionsintoasinglepackage.Eachprotectionelementisdesignedtodetectaspecificabnormalconditioninthesystemandtoinitiateaparticulartrippingsequence.Statictestingofindividualfunctionsinmanycaseswillnotvalidatetheabilityoftheentirepackagetorespondcorrectlytodifferentsystemconditions.Thisisparticularlytrueforgeneratorprotection.EMTP-typesimulatorsmaynotallowcomprehensivedynamictestingduetolimitationsinthemodels(simulationoftrueinternalfaultsinmachinesandtransformers,generationofnaturalthirdharmonicsbyagenerator,etc.).Thereforeinsomecasessuchasungroundeddistributionnetworks,generator,motorandtransformerprotection,physicalmade-to-scalemodelsoftheprotectedequipment,andactualfieldrecordingsareexceptionallyuseful.Thispaperwilldemonstratetheadvantages,methodologyandsampleresultsofdynamicre-laytestingusingascaledmodelgeneratorplatform.Someoftheofabnormalconditionsappliedtotherelayinclude:•Internalfaults(trueturnfaults)•ExternalfaultswithCTsaturation•Lossofprimemover•Over/underexcitation•Stable/unstablepowerswings•Inadvertentenergization•Lowfrequencyoperation(staticstarting)•LossofexcitationAnewgeneratorrelayistestedonouruniquephysicalmodelandstate-of-the-artdigitalsimulator.Particularattentionispaidtonewalgorithms,suchasstatordifferentialwithextraimmunitytoCTsaturationconditions.Sampletestresultsareincluded.2.SimulationandTestingTools:AnalogversusDigital2.1.GeneratorTestingNeedsThemodelforin-depthtestingofamoderngeneratorprotectiverelayshouldconsistofthefollowingcomponents:•Asynchronousgeneratorwithelectricalparametersconsistentwiththoseofatypicalhigh-voltagegenerator.Thegeneratorshouldproduceathirdharmoniccomponentwithavoltagedistributionthatistypicalofahigh-voltagegenerator.•Aprimemoverwithacontrolsystemcapableofconstantspeedand/orconstantrealpowercontrolandwithmatchinggainsandtimeconstants.•Anexcitationsystemwithacontrolsystemcapableofconstantvoltageand/orcon-stantreactivepowercontrol.Systemgainsandtimeconstantsshouldmatchtherealworldequivalents.DynamicTestingofGeneratorProtectionUsingaModelGeneratorPlatformPage3of18•Ahigh-voltage-interconnectsystemconsistingofageneratorgroundingsystem,unittransformer,circuitbreaker,transmissionlinemodel,andequivalentgridsystem.Thetransmissionlinemodelshouldallowforthesimulationofbothstrongandweaksys-tems.Themodelshouldbecapableofoff-lineandon-lineoperatingmodes.Inon-linemodethemodelshouldbecapableoftransferringrealandreactivepowertoanequivalentgridsystem.Themodelshouldallowfortheapplicationofphase-to-phaseandphase-to-groundelectricalfaultsatthefollowingpoints:•Theneutralofthemachine.•Atvariouspointsonthestatorwinding.•AtthemachineterminalswithinthezoneformedbythegeneratorCurrentTransform-ers(CTs).•AtthemachineterminalsoutsidethezoneformedbythegeneratorCTs.•Atvariouspointsonthetransmissionlinemodel.Themodelshouldallowfortheapplicationofthefollowingabnormalconditions:•Alossofprimemover.•Alossofexcitation.•Over/under-excitation.•Over/under-voltage.•Over/under-frequency.•Anopenphaseorphaseunbalance.•Accidentalenergization.•Generationrejection.ThemodelshouldpermitforbothwyeandopendeltarelayVoltageTransformer(VT)con-nections.InadditionthemodelshouldallowforthesimulationofafailureofoneormoreVTfuses.TheCircuitBreaker(CB)shouldbecontrollablefromtheprotectiverelayandtheCBposi-tionshouldbeavailableasastatusinputtotherelayundertest.2.2.InternalFaultsThisisprobablythesinglemostimportantreasonforbuildingandusinganalogsimulators.Inthecaseofrotatingmachinesandpowertransformers,internalshortcircuitscanoccurbetweendifferentpointsofthesamewinding,betweendifferentwindings,orbetweenawindingandacore,allwithinthecomplexmagneticcoreoftheapparatus.Inthecaseofrotatingmachinery,thesituationisevenmorecomplicatedaspartoftheapparatusrotates.Becausemodelingofsuchtrue“inner”faultsisacomplextask,testingforinternalfaultsistypicallylimitedtofaultsatthemachine/transformerterminalswithinthedifferentialzoneofprotectionasoutlinedbythemainCTs.Inthecaseofpowertransformers,severalattemptshavebeenmaderecentlytomodeltrueinternalfaults[1].Someofthesolutionshavebeenincorporatedintocommerciallyavailablesimulationpackagesoraspre-processorstostandardsimulationtoolssuchatATP/EMTP.DynamicTestingofGeneratorProtectionUsingaModelGeneratorPlatformPage4of18Someattemptsatmodelingtrueinternalfaultsinrotatingmachines,generatorsinparticular,havebeenmadeaswell,buttheindustryisfarfromseeingthemodelsvalidatedandincorporatedinstandardsimulationpackages.Analogsimulationusingmade-to-scalemachin