文档名：弱电网下并网逆变器恒定带宽及稳定裕度的自适应控制策略
摘要：随着可再生能源在电网中的占比不断提高,电网逐渐呈现出弱电网特性,即电网阻抗不可忽略且频繁波动.电网阻抗的存在会改变逆变器控制环路的增益,导致控制环路的稳定裕度减小,因而引发稳定性问题,同时,控制环路的截止频率也因电网阻抗的存在而减小,环路带宽也随之减小,使得逆变器动态性能变差.针对弱电网下电网阻抗变化引发的相关问题,现有的控制策略往往侧重于提升逆变器的并网稳定性,而对其动态性能下降的问题缺乏关注.鉴于此,为同时解决以上问题,该文提出一种基于环路增益测量的自适应控制策略以保障逆变器优越且恒定的控制性能,首先通过环路增益的在线测量实现对逆变器控制性能的实时监测;然后依据实时监测的控制性能指标参数自适应地调整控制器的参数,以提升逆变器对弱电网的适应性;最后以单相并网逆变器为例进行实验验证,实验结果证明了所提方案的有效性.
Abstract：Drivenbythelarge-scaleadoptionofelectronicpowerconvertersforwidespreadrenewablegeneration,powergridsgraduallypresentweakgridcharacteristics,i.e.,thegridimpedancecan'tbeignoredandfluctuatesfrequently.Thegridimpedancedirectlyaffectsthecontrolloopgainofinverters,whichcandecreasethestabilitymarginandleadtopoordynamicperformance.Tosolvetheseissuesjointly,anadaptivecontrolstrategybasedonloopgainmeasurementtechniqueisproposedinthisworktoimprovetheadaptabilityofinverterstopre-unknownweakgridconditions.Theproposedadaptivecontrolstrategyincludestwoimportantsteps:(1)Themonitoringofcontrolperformanceindexesand(2)Auto-tuningofcontrollerparameters.Firstly,acontrolperformancemonitorisproposedforonlinemonitoringofcontrolperformanceindexes(crossoverfrequencyfc,phasemargin?M)ofinvertersystems.Theseindexescanbeusedtocharacterize,inrealtime,thedynamicperformanceandstability,respectively.TheproposedcontrolperformancemonitorisdesignedbasedonMiddlebrook'sloopgainmeasurementtechniquewithsmallsignalinjection.Thecorrespondingsignalextractionstructureisrealizedbyahigh-passsecondordergeneralizedintegrator(HPSOGI),whichcanenhancetheattenuationabilityoflow-frequencyharmonics.Withthemeasuredperformanceindexes(fc,?M),anauto-tuneristhendesignedtoadjustcontrollerparametersofinvertersaccordingly.Thesensitivityanalysismethodisadoptedtodecouplethecontrollerparameters(Kp,Kr)andcontrolperformanceindexes(fc,?M).Ageneraladaptivelawisthereforedesignedasfollowing:thecrossoverfrequencyfcisdesignedtoadjusttheproportionalgainKpuntilthedesiredcrossoverfrequencyfREFcisachieved;thephasemargin?MisdesignedtoadjusttheresonancegainKruntilthedesiredphasemargin?REFMisachieved.Inthisway,highdynamicperformanceandsufficientstabilitymargincanbeguaranteedsimultaneouslybytheproposedauto-tuner.Additionally,therelevantparametersselectionanddesignofregulatorsarediscussed.Theexperimentalresultsshowthatthemonitoringprocesscanbecompletedwithin60mswithanaccuracyof96%,whichissufficientforthesubsequentauto-tuningprocess.Boththemeasurementtimeandtheaccuracycanbefurtherimprovedbyrefiningtheauto-tunercoefficients.Withtheproposedadaptivecontrolstrategy,thecrossoverfrequencyandphasemargincanbemaintainedatexpectedvalue(fc=1kHz,?M=45°)undergridimpedancevariationsandlow-voltageridethroughconditions.Withtheincreasedloopgain,totalharmonicdistortion(THD)oftheinjectedgridcurrentisalsodecreased.Thefollowingconclusionsaredrawnfromthispaper:(1)TheHPSOGIstructureadoptedincontrolperformancemonitorcanimproveaccuracyandspeedofthemonitoringprocess.(2)SensitivityanalysismethodcanbeusedtodesignadaptivelawtoimprovetheadaptabilityofadaptivecontrolstrategytovariousregulatorssuchasPIandPRregulator.(3)Theproposedadaptivecontrolstrategycanmaintainhighdynamicperformanceandsufficientstabilitymarginofinvertersystemundergridimpedancevariationandfaultconditionssuchaslow-voltageridethrough.
作者：曾祥辰 刘青 王嘉晨 辛振Author：ZengXiangchen LiuQing WangJiachen XinZhen
作者单位：省部共建电工装备可靠性与智能化国家重点实验室(河北工业大学)天津300401
刊名：电工技术学报
Journal：TransactionsofChinaElectrotechnicalSociety
年，卷(期)：2024, 39(9)
分类号：TM464
关键词：稳定性 自适应控制 弱电网 并网逆变器
Keywords：Stability adaptivecontrol weakgrids grid-connectedinverters
机标分类号：TN713TM464TM315
在线出版日期：2024年5月13日
基金项目：国家自然科学基金，河北省自然科学基金绿色通道项目，河北省留学人员资助项目弱电网下并网逆变器恒定带宽及稳定裕度的自适应控制策略[
期刊论文] 电工技术学报--2024, 39(9)曾祥辰 刘青 王嘉晨 辛振随着可再生能源在电网中的占比不断提高,电网逐渐呈现出弱电网特性,即电网阻抗不可忽略且频繁波动.电网阻抗的存在会改变逆变器控制环路的增益,导致控制环路的稳定裕度减小,因而引发稳定性问题,同时,控制环路的截止频率...参考文献和引证文献
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