3_HVDC-08PSCAD浙大研修班(仅供参考学习) (1)

HVDCTrainingIntroductiontoHVDCSeminar周铮July2008HVDCTrainingAgenda•HVDCBackgroundandHistory•HVDCConfigurationandEquipment•HVDCBasicDefinitions/Equations•HVDCACsystemrequirements•BasicConversionProcess•SimpleConversionDemo•HVDCControlsandPowerTransfer–PSCADDemo•HVDCControlsSystem–PSCADdemoshowingControlactions–HVDCTrainingWhyUseDCTransmission•HVDCHistory1929,1950,1954–MatureTechnologyandlargeworldwideinterest(ShowHVDCprojectListings_IEEE)•Smallertower:2versus3conductors•DCLowerTransmissionLosses–ACLineeffectsinoverheadlinesorCables•ControlofPowerFlowDirectly•ConnectAreaswithdifferentfreq.OrFreqPhase•Control/Stabilitysystemsupportoptions•SeparationofLargeAreasintoRegions.–USAblackout2003-didnotimpactQuebec–HVDCTrainingHVDCTrainingRectifierInverter1Valvegroup2ACFilter3Convertertransformer4DCfilter5Ground/seaelectrodeormetallic6Receivingacsystem7Sendingacsystem1345276+-PowerIdIdVdorEdHVDCTrainingManitobaHenday+/-500kV2000MWHVDCTrainingCigre2008:PaperB4:117HVDCTrainingWhyNotUseDC•HighCostofConversionequipment•Transformationandtappingpowerisnoteasyorpossible•PossibleHarmonicInterferencewithCommunicationCircuits•Groundcurrents(electrode)•HighReactivePowerRequirementsateachterminal•Lackofskilled“specialty”workforce.HVDCTrainingHVDCConfigurations•Monopolar,Bipolar,withoverheadlineand/orcable•Seriesgroups,ParallelPoles•BacktoBackBTB•Multi-terminal•Voltagesource(VSC)HVDCTrainingVSCHVDC•VSC–VoltageSourcedConverter•Operatesintolowshortcircuitoreven“dead”acnetworks.•IGBTtechnologytodaywouldallowhundred’smegawatts.BothABBHVDCLightandSiemensHVDCPlusaretalkingabout1000-2000MWVSCschemesHVDCTraining•ThyristorCharacteristics–PositivevoltageAnodetoCathode–GateorFiringPulse–CannotstopcurrentexceptatcurrentzeroFundamentalsofConvertorOperationHVDCTrainingThreePhaseGraetzBridge•3Phase6PulseBridge•BasicHVDCBuildingBlockHVDCTrainingGotoCommutationPresentationHVDCTraining•DiodeNaturalCommutation•V1+,V2-,V3+,V4-,V5+,V6-,V1+•DefinedasAlpha=0•IdealWaveforms,NoDelay6POperationHVDCTraining•UseSimple6PExampleBasicWaveforms6PHVDCTrainingIncludesEffectofCommutationReactance•CurrentcannotchangeInstantly•Effectivevoltagedrop•AddsNotchingtoVoltageWaveforms•WhydoweneedcommutationReactance?HVDCTrainingFiringAngle•Thyristors=Delayinfiring,aslongasvoltageispositiveanodetocathode.•DelayangleAlpha∝•0Alpha90Rectifier•90Alpha180InverterHVDCTrainingVariationofDCVoltagewithFiringAngleP=1.0pu,Q=0.6puRectifierP=-1.0pu,Q=0.6puInverterHVDCTrainingDefinitionsinConverterαμγβIv3Iv1180oα+μ+γ=180oγ=β–μ=180o–aHVDCTrainingDelayangle(firingangle):•ThetimeexpressedinelectricalangularmeasuredfromthezerocrossingoftheidealizedsinusoidalcommutatingvoltagetothestartinginstantofforwardcurrentconductionOverlapangleμ.•Thedurationofcommutationbetweentwoconvertervalvearmsexpressedinelectricalangularmeasure.Extinctionangleγ.•ThetimeexpressedinelectricalangularmeasurefromtheendofcurrentconductiontothenextZerocrossingoftheidealizedsinusoidalCommutatingvoltage.ConverterOperationandCalculationHVDCTrainingHVDCTrainingHVDCTrainingInverterCommutationFailuresCommutationfailuresaretheresultoftheincomingvalvefailingtotakeoverthecurrent,orre-fireoftheoutgoingvalve.Commutationfailuresaredueto:•ACsystemfaults&disturbances.•DCfaultsordisturbances.•EquipmentfailuresHVDCTraining62135TSR4HVDCTrainingHVDCTraining62135TSR4HVDCTraining62135TSR4HVDCTraining62135TSR4HVDCTrainingHarmonics•DCVoltage•kP•For6Pulse–6,12,18etc..•For12Pulse–12,24,36•ACCurrent•k(P-1,P+1)•For6pulse–5,7,11,13,17,19•For12Pulse–11,13,23,25HVDCTrainingBasicDCEquationsReactivePowerRequirementatbothRectifierandInverterIdXcEllVd*cos(**35.1aIdRVd*IdVdcPdc*HVDCTrainingDefinitionSCRandESCRSCR=SCC/PdWhereSCCistheshortcircuitcapacityPdistherateddcpowercapacityinMWESCR=(SCC-Qcomp)/PdWhereQcompisthereactivecompensationconnectedtotheacbusHVDCTrainingDefinitionESCR--------------------------------------------High2.5Low1.5–2.5VeryLow1.5ACSystemImpactsSystemStrengthDefinitionsHVDCTrainingShowBuildCurrentcontrollerwith12PulseRectcaseHVDCTrainingHVDCControlSystemsIdXcEllVd*cos(**35.1a•BasicHVDCTransmissionSystem•Id=(Vrec-Vinv/Rline)•Pd=Vd*IdHVDCTrainingVd–IdCharacteristicsVdIdα=minRectifierandinverterConstantγ=18ΔId=.1PuHVDCTrainingHVDCControlDiagramsHVDCTrainingVDCOL(VoltageDependentCurrentOrderLimit)HVDCTrainingOverallBlockDiagramHVDCTrainingUseHVDC1caseHVDCTrainingSourcesofReactivePower•ACFilters•ShuntCapacitors•SynchronousCondensors•StaticVarCompensators(SVC)•STATCOMHVDCTrainingTheValveisKingdi/dtdv/dtOverVoltageOverCurrentTemperatureHVDCTrainingThankyou…Questions?