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±1100kV特高压换流站直流操作过电压研究.docx

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±1100kV特高压换流站直流操作过电压研究 Abstract Theoperatingovervoltageina±1100kVultrahighvoltage(UHV)converterstationplaysanimportantroleinthesafeandstableoperationofthepowertransmissionsystem.ThispaperanalyzesthecausesofoperatingovervoltageinUHVconverterstations,studiesthecharacteristicsoftheovervoltagewave,andproposesmeasurestopreventandcontroltheovervoltageinUHVconverterstations.Theresultsshowthattheappropriateselectionofswitchingdevices,theoptimizationoftransformerparameters,andtheimprovementofinsulationcoordinationareeffectivewaystopreventandcontroltheovervoltageintheUHVconverterstation. Introduction Withtherapiddevelopmentoftheelectricityindustry,thepowertransmissioncapacityofultrahighvoltage(UHV)systemscontinuestoincrease.UHVsystemshavetheadvantagesoflesslandoccupation,lowtransmissionloss,andhightransmissionefficiency,whicharecrucialfactorsforpromotinggreenenergydevelopment.However,withUHVtransmissiontechnologyadvancing,theultra-highvoltageconverterstationisthemostimportantkeylinkinUHVpowergrid,anditsoperatingreliabilityandstabilitydirectlyaffectthesafeandefficientoperationoftheUHVpowergrid. OperatingovervoltageisoneofthemainfactorsaffectingthesafeandreliableoperationoftheUHVconverterstation.Itcancauseinsulationbreakdownofequipment,reducetheinsulationlife,andevenleadtothecollapseofthepowergrid,resultinginhugeeconomicandsociallosses.Therefore,itisparticularlyimportanttostudytheoperatingovervoltageoftheUHVconverterstation. CausesofOperatingOvervoltageinUHVConverterStations ThereareseveralcausesofoperatingovervoltageintheUHVconverterstation,whicharemainlycausedbytheswitchingoperationoftheconvertervalves.TheUHVconverterstationusesthyristorvalvestorealizetheconversionbetweenACandDCpower.Duringtheswitchingprocess,overvoltageisgeneratedduetothevoltagechangeonthetransformerside.ThecausesofovervoltageintheUHVconverterstationareasfollows: 1.Transformerinrushcurrent. 2.High-frequencyoscillationduringthepowerfrequencyzero-crossing. 3.ResonancebetweentheACfiltercircuitandtransformerpara