文档名：适用多功率的最近电平调制下MMC子模块开路故障诊断策略
摘要：模块化多电平换流器(MMC)子模块(SM)发生故障时,快速检测到故障并定位故障SM是提升MMC可靠性的关键.现有研究基于经验的阈值设置在不同运行功率间难以推广.针对于此,提出一种适用于不同运行功率的最近电平调制(NLM)策略下MMC子模块开路故障诊断策略.所提策略通过判断SM电容电压预测值与实际值间的绝对误差是否超出阈值来检测并定位故障.通过数学推导给出了设置阈值的可靠依据,并验证了当运行功率发生改变时无需重新手动设置阈值,与现有研究相比降低了阈值设置难度.此外,所提策略整合了现有策略的优点,包括无需额外硬件,计算负担小,诊断速度快(＜20ms),适用于多个SM发生故障的情形等.同时,通过理论分析验证了所提策略不仅适用于NLM策略的情形,在调整SM开关函数的预测方法后可推广至其他MMC调制策略.在硬件在环平台中的实验结果验证了该策略可以在不同功率点准确、快速地诊断出两种MMC子模块开路故障.
Abstract：Withtheincreasingvoltageandpowerlevelofmodularmultilevelconverters(MMC),thenumberofitssubmodules(SMs)alsoincreases,andtheissueofitsreliabilityishighlighted.ThefailureofIGBTinanySMcanaffectthenormaloperationofMMCandevenfurtherleadtothedamageofothercomponents,whicheventuallyleadtothecollapseofthewholesystem.Thus,itisnecessarytodetectthefaultandlocatethemalfunctioningSMsaccuratelytoimproveitsreliability.MMC'sSMopen-circuitdiagnosisstrategycanbedividedintotwocategories:hardware-basedandsoftware-based.Comparedwiththehardware-basedstrategy,thesoftware-basedstrategiesneednoextrahardware,havelowcomputationalburden.However,itisdifficulttosettheempiricalthresholdofexistingsoftware-basedstrategiesbetweendifferentoperatingpowers,whichhindersitsfurtherdevelopment.Tosolvethisissue,adiagnosisstrategyforopen-circuitSMfaultsinMMCssuitablefordifferentoperatingpowersisproposed.TheSMswitchingfunctionispredictedbasedonthenumberofSMinputsandthepositionofSMcapacitorvoltagesortingarrangementandthenthecorrespondingSMcapacitorvoltageispredicted.Onthebasis,thefaultisdetectedandlocatedbyjudgingwhethertheabsoluteerrorbetweenthepredictedvalueandtheactualvalueoftheSMcapacitorvoltageexceedsathreshold.Moreover,tofurthereliminatetheeffectsoferrorsandpreventtheexistenceoffaultmisdiagnosissituations,atimeflagisusedinboththedetectionprocessandlocationprocess.Intheproposedstrategy,toavoidtheeffectsofmisdiagnosisnearthearmcurrent-over-zeropoint,acurrent-over-zerofilteringpartisproposed.Basedonthemathematicaldeduction,theprincipleofsettingthresholdisgiven.ItisindicatedthattheproposedstrategyeliminatestheneedtomanuallysetthethresholdwhentheMMCoperatingpowerchanges,whichgreatlyreducethedifficultyofsettingthethresholdcomparedwiththeexistingstrategies.Atthesametime,theoreticalanalysisverifiesthattheproposedstrategyisnotonlysuitableforNLMmodulationstrategy,butalsocanbeextendedtootherMMCmodulationstrategiesafteradjustingthepredictionmethodofSMswitchingfunction.Adetailedreal-timedigitalsimulationmodeloftheMMC-HVDCsystemisbuiltinahardware-in-the-loopplatform.Thepower-stagemodelisemulatedbythetargetmachineandthecontrolsystemisrealizedbytheDSPTMS320F28335controlboard.TheexperimentalresultverifythattheproposedstrategycanaccuratelydiagnosetwotypesofMMCSMopen-circuitfaultsatdifferentoperatingpowers.ItisobservedthattheabsoluteerrorofaTypeImalfunctioningSMishighwhenthearmcurrentisnegativeandtheabsoluteerrorofaTypeIImalfunctioningSMishighwhenthearmcurrentispositive,whichverifiesthecorrectnessofthetheoreticalanalysis.Beforethefaultoccurs,theabsoluteerrorwillnotexceedthethresholdsothatmisdiagnosiswillnotoccurduringnormaloperation.Afterthefaultoccurs,theabsoluteerrorexceedsthethreshold,thesystemcanquicklydetectthefaultandthenlocatetheremainingmalfunctioningSMs.Moreover,theproposedstrategyintegratestheadvantagesofexistingstrategies,includingnoextrahardware,lowcomputationalburden,fastdiagnosis(＜20ms),andcancopewiththecasesofmultipleSMfailuresinthearm.
作者：武鸿 王跃 薛英林 刘熠 李鹏坤 Author：WuHong WangYue XueYinglin LiuYi LiPengkun
作者单位：电力设备电气绝缘国家重点实验室(西安交通大学)西安710049国网经济技术研究院有限公司北京102209
刊名：电工技术学报
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(1)
分类号：TM46
关键词：模块化多电平换流器 运行功率 故障诊断 绝对误差
Keywords：Modularmultilevelconverter operatingpower faultdiagnosis absoluteerror
机标分类号：TM721.1TM46TH16
在线出版日期：2024年1月18日
基金项目：国家电网公司科技项目适用多功率的最近电平调制下MMC子模块开路故障诊断策略[
期刊论文] 电工技术学报--2024, 39(1)武鸿 王跃 薛英林 刘熠 李鹏坤模块化多电平换流器(MMC)子模块(SM)发生故障时,快速检测到故障并定位故障SM是提升MMC可靠性的关键.现有研究基于经验的阈值设置在不同运行功率间难以推广.针对于此,提出一种适用于不同运行功率的最近电平调制(NLM)策...参考文献和引证文献
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