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1、第33卷第1期高电压技术Vol.33No.1·26·2007年1月HighVoltageEngineeringJan.20073基于故障电阻测量的小电流接地系统保护方法1121曾祥君,王媛媛,庞方亮,李景禄(11长沙理工大学电气与信息工程学院,长沙410076;2,湖南株洲县电力局,株洲412100)摘要:为解决小电流接地系统高阻接地故障检测的难题,分析了单相接地故障前后相电流变化特征:故障线路的故障相与非故障相电流变化量之差等于接地故障电流,非故障线路的故障相与非故障相电流变化量相等;并由故障相电压与故障电流之比计算出接地
2、故障电阻,发明了基于接地故障电阻测量的高阻接地保护方法。EMTP仿真分析和动模实验测试结果表明,该保护方法能够保护各种高阻接地故障,具有较高的保护精度和可靠性,适合在配电自动化终端单元(FTU)上就地实现。关键词:小电流接地系统;高阻接地故障;故障选线;继电保护;相电流中图分类号:TM711;TM773文献标识码:A文章编号:100326520(2007)0120026205GroundingFaultProtectionBasedonFaultResistanceMeasurmentforIneffectivelyEart
3、hedDistributionSystems1121ZENGXiangjun,WANGYuanyuan,PANGFangliang,LIJinglu(1.SchoolofElectrical&InformationEngineering,ChangshaUniversityofScienceandTechnology,Changsha410076,China;2.TheElectricPowerCompanyofZhuzhouCounty,Zhuzhou412100,China)Abstract:NeutralIneffec
4、tivelyEarthedPowerSystems(NIEPS)includeneutralunearthedsystem,neutralearthedwithhighresistancesystemandneutralresonanceearthedsystem.Single2phasegroundingfaultspotentiallycausecablebombingorphase2to2phasefaultsinNIEPS,andthesafetyandpowerqualityofthedistributionsys
5、temwillbeaffected.HighimpedancegroundingfaultsaredifficulttodetectwithtraditionalmethodsinNIEPSbecauseofminorfaultcurrent,faultarc,harmonicsinfluenceandtheprotectionprinciplelimitation.Inordertoimprovetheprecisionandreliabilityoftraditionalgroundingfaultprotections
6、chemesforNIEPS,thecharacteristicsofphasecurrentvaria2tionsbeforeandaftergroundingfaultoccurringareanalyzedinthepaper.Thedifferenceofphasecurrentvariationsbetweenthefaultphaseandanormalphaseinthefaultedfeederequalstothegroundingfaultresidualcurrent,andthedifferencei
7、nthenormalfeederequalstozero.Thefaultresistanceequalstheratiobetweenfaultphasevoltageandfaultcurrent.Thefaultresistancebasedprotectionisthenputforward.Whenthefaultcurrentishigherthanitsthresholdortheresistanceislowerthanitsthreshold,groundingfaultoccursintheprotect
8、edfeeder.EMTPsimula2tionandexperimentalresultsshowthatthemeasurementiswithhighprecision,andtheprotectioniswithhighsen2sitivityandrobustnesstodete
