文档名：计及控制响应的多端混合直流输电系统短路电流近似计算方法
摘要：多端混合直流输电系统故障发展迅速、短路电流水平超标问题严重,换流站高度非线性特征使现有短路电流求解忽略了控制系统的响应过程且多依赖建模仿真结果,无法得到短路电流的具体解析式,实现故障特性的定量分析计算.为此,该文提出三种兼顾准确性与计算复杂程度的系统模型简化措施,并在此基础上提出计及控制系统作用的短路电流复频域近似求解方法,利用Pade逼近以及分段线性化法对模型进行降阶处理,通过拉普拉斯逆变换求得短路电流的时域解析式.最后,基于PSCAD/EMTDC对不同故障距离、过渡电阻以及故障类型进行了仿真分析.结果表明,该方法能在故障的暂态阶段(10ms内)对短路电流有较为准确的刻画,能为直流保护定值整定、断路器额定容量选取、直流输电控制策略切换以及系统规划设计等提供重要依据.
Abstract：ThehybridDCtransmissionsystem,whichgivesfullplaytotheadvantagesofconventionalDCandflexibleDC,hasbecomearesearchhotspotinthefieldsoflong-distancetransmissionandrenewable-energygridconnection.However,HVDCtransmissionlinesarelongandtheworkingenvironmentiscomplex,resultinginhighfaultprobability.Onceashort-circuitfaultoccursontheDCline,itwillgeneratefaultcurrentseveraltimestheratedcurrentwithin10ms,exposingthewholesystemtoaseriousovercurrentriskandthreateningthesTab.operationofthesystem.Inaddition,thehighlynonlinearcharacteristicsoftheconverterstationmaketheexistingshort-circuitcurrentsolutionsignoretheresponseprocessofthecontrolsystemandrelyonthemodelingandsimulationresults.Itisimpossibletoobtainthespecificanalyticalformulaoftheshort-circuitcurrenttorealizethequantitativeanalysisandcalculationofthefaultcharacteristics,whichbringsdifficultiestotheprotectionanddesignofDCcontrolsystemsandrestrictsthedevelopmentofhybridDCtransmissiontechnologies.Therefore,consideringcontrolresponse,anapproximatecalculationmethodforshort-circuitcurrentofmulti-terminalhybridDCtransmissionsystemsisproposed.First,threesystemmodelsimplificationmeasuresareproposed,whichtakeintoaccountbothaccuracyandcomputationalcomplexity,includingportprocessing,non-fault-poledischarging-loopprocessingandACsystemprocessing.Second,thesystemtopologymodelandcontrolmodelaremodeled.Basedonthefault-componentnetwork,theshort-circuitcurrentisobtainedregardlessoftheactionofthecontrolsystem,andthenthecorrectedcurrentunderthecontrolactionisobtainedbyusingthiscalculationresult.Thetwoaresuperimposedtoobtainthefinalcomplexfrequencydomainanalyticalformulafortheshort-circuitcurrent,andtheinverseLaplacetransformisusedtoobtainthetime-domainsolutionfortheshort-circuitcurrent.TheproposedmethodcorrectsthetriggerangleoftheLCCside,usingPadeapproximationandpiecewiselinearizationmethodtoreasonablyreducetheorderofshort-circuitcurrentmodel,whichtakesintoaccountthecalculationaccuracyandefficiency,toeffectivelyavoidtheproblemthattheinverseLaplacetransformcannotbesolvedduetothehighorderofcomplexfrequencydomainexpression.Finally,basedonPSCAD/EMTDC,thesimulationanalysisondifferentfaultdistances,transitionresistanceandfaulttypesiscarriedout.Itcanbeconcludedthat,theproposedmethodcanaccuratelydescribethetransientcharacteristicsandtrendofthefaultcurrentattheoutletofeachconverterstationbeforetheblockingoftheMMCstation,obtainingtheanalyticalexpressionofthefaultcurrentwhichprovidesaquantitativecalculationmethodoffaultcurrentforpowergridplanning,equipmentparameterselectionandprotectionsetting.Inaddition,thetransientcurrentincrementconsideringthecontrolcharacteristicsoftheconverterstationislessthanthatwithoutconsideringthecontrolcharacteristics.Therefore,thefaulttransientcharacteristicscanbequicklyanalyzedandjudgedbyusingthefaultcurrentcalculationresultswithoutconsideringthecontrol.Finally,itcanbeconcludedthat,intermsofcalculationefficiency,theproposedmethoddoesnothavetheproblemofexcessivecomputationalcomplexityduetotheorderreduction.Thecalculationerrorismainlyrelatedtothefactorsneglectedorsimplifiedinthecalculationprocess,includingtheapproximateequivalentprocessingofthemodel,theapproximatefittingprocessofthewaveformandtheaccuracyreservedwhentheintermediatevariablesareobtained,buttheoverallrelativeerrorisstillcontrolledwithin10%tomeettheaccuracyrequirementsoffaultcurrentcalculation.
作者：李杭泽 戴志辉 石旭 杨明玉Author：LiHangze DaiZhihui ShiXu YangMingyu
作者单位：新能源电力系统全国重点实验室(华北电力大学)保定071003
刊名：电工技术学报
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(9)
分类号：TM713
关键词：短路电流计算 控制系统 网络等值 多端混合直流输电 线路故障
Keywords：Short-circuitcurrentcalculation controlsystem networkequivalence multi-terminalhybridHVDCtransmission linefault
机标分类号：V274TM751O226
在线出版日期：2024年5月13日
基金项目：国家自然科学基金计及控制响应的多端混合直流输电系统短路电流近似计算方法[
期刊论文] 电工技术学报--2024, 39(9)李杭泽 戴志辉 石旭 杨明玉多端混合直流输电系统故障发展迅速、短路电流水平超标问题严重,换流站高度非线性特征使现有短路电流求解忽略了控制系统的响应过程且多依赖建模仿真结果,无法得到短路电流的具体解析式,实现故障特性的定量分析计算.为此...参考文献和引证文献
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计及控制响应的多端混合直流输电系统短路电流近似计算方法 Approximate Calculation Method of Short-Circuit Current of Multi-Terminal Hybrid DC Transmission System Considering Control Strategy
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