基于谐波的低压配电干线中性线断线检测方法.pdf

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1、第42卷第19期电力系统保护与控制V01．42N0．192014年10月1日PowerSystemProtectionandControl0ct．1．2014基于谐波的低压配电干线中性线断线检测方法雍静，周浩(输配电装备及系统安全与新技术国家重点实验室(重庆大学)，重庆400030)摘要：三次谐波电流含量较大是目前低压配电系统负荷的普遍特征，利用这一特征，提出了在配电干线首端设置监测装置，对中性线断线故障进行检测的保护方法。其基本原理是通过检测线路首端三次谐波变化来判断是否发生中性线断线故障。仿真和实测分析表明：无论故障点以后的负荷是否平衡，

2、当中性线断线时线路首端三次谐波均会呈现不同程度变化，故障点越接近线路首端，故障导致的三次谐波变化就越显著对中性线断线故障时线路首端三次谐波和基波的突变规律，以及正常运行时，负荷三次谐波和基波的波动规律进行了研究和分析，获得了将故障和正常运行状态进行有效区分的故障判据和故障判别流程。利用实测负荷的波动数据进行仿真研究，验证了故障检测判据在负荷平衡和不平衡状态下对中性线断线故障判别的有效性。关键词：谐波；中性线断线故障；故障检测；负荷不平衡Aharmonic--basedapproachforopen-·neutralfaultdetection

3、inlowvoltagesystemsYONGJing，ZHOUHao(StateKeyLaboratoryofPowerTransmissionEquipment&SystemSecurityandNewTechnology(ChongqingUniversity)Chongqing400030，China)Abstract：Inlow—voltagedistributionsystem3rdharmoniccurrentcontentisbigenough．Itisacommoncharacteristics．Throughanalyzi

4、ngthecharacteristicsofharmonic，anewopen—neutralfaultdetectionapproachisproposedthatmonitoringdevicecarlbesimplyinstalledatfeederhead．Mainideaoftheproposedapproachisthatthefaultcanbeidentifiedaccordingtothe3rdharmonicvariationmeasuredatthefeederhead．Simulationandexperimental

5、analysisshowsthatthe3rdharmoniccurrentwillshowvaryingdegreesofchangeatthefeederheadwhenopenneutralfaultoccurs，regardlessoftheloadisbalancedorunbalanced．Thefaultlocationisclosertofeederheadindicatesthatthe3rdharmoniccurrentchangeismoresignificant．Thispaperresearchesandanalyz

6、esthe3rdharmonicandfundamentalcurrentssuddenchangemethodatfeederheadwhenopen—neutralfaulthappened，aswellas3rdharmonicandfundamentalcurentsofloadfluctuationmethodduringnormaloperation．Itobtainsfaultcriterionandfaultidentificationprocessesthatcanefectivelydistinguishbetweenop

7、en—neutralfaultandnormaloperation．Theexperimentallymeasuredloadfluctuationdataforsimulationstudyverifiesthefaultdetectioncriterionisvaliditytoopen-neutralfaultwheneverinbalancedandunbalanced1oadconditions．ThisworkissupposedbyNationalNaturalScienceFoundationofChina(No．510771

8、38)．Keywords：harmonics；openneutralfault；faultdetection；loadimbalance中图分类号：TM645文献标