小电流接地选线系统

毕业设计题目：小电流接地选线系统院、系：电气工程及其自动化姓名：指导教师：系主任：2014年6月8日I小电流接地选线系统摘要我国中低压配电网中性点广泛采用小电流接地方式，这种接地方式具有供电可靠性高的优点。但发生单相接地故障后，由于故障电流微弱、电弧不稳定等原因，单相接地故障选线和故障定位问题长期以来没有得到很好地解决，至今许多变电站仍然使用人工拉路方法查找故障线路和自测法寻找故障点。本论文重点研究配电网单相接地故障选线及故障定位问题。通过对配电网单相接地故障暂态过程的深入分析得知：线路存在串联谐振过程和并联谐振过程，线路发生谐振时，故障线路的阻抗时而程容性，时而程感性，其特性受系统出线数、各线路长度等因素的影响较大，此时故障线路零序电流与所有非故障线路零序电流关系较为复杂。通过分析多种选线方法的优缺点，本文最终选择了信号注入法。分析了注入信号法选线定位原理，指出注入信号法实质上是人为增加了零序电流。讨论了注入信号的探测方法，提出用零序电流互感器探测注入信号的方法。分析了影响注入信号电流在故障线路中流通的因素和注入信号电流的相位特征，指出注入信号电流的相位特征只能作为选线的辅助判据。关键词小电流接地系统；单线接地故障；故障定位；信号注入IIThesmallcurrentgroundinglineselectionsystemAbstractInourcountry,widelyusedinlowvoltagedistributionnetworkneutralsmallcurrentgroundingmethod,thegroundingmethodhastheadvantageofhighpowersupplyreliability.Butafterthesingle-phaseearthfaultoccurs,suchasweakfaultcurrentandarcstability,single-phaseearthfaultlineselectionandfaultlocationproblemforalongtimehaven'tbeensolvedwell,uptonowmanysubstationstillusemanualpullwaymethodtofindthefaultlineandtheself-testmethodtofindfaultpoint.Thispaperfocusesonpowersingle-phaseearthfaultlineselectionandfaultlocationproblem.Throughthedistributionnetworkofsingle-phaseearthfaulttransientprocessofthethoroughanalysisthatseriesresonanceprocessandparallelresonantcircuit,circuitresonanceoccurs,theimpedanceofthefaultlineandsometimesChengRongsex,sometimesperceptualprocess,itscharacteristicstoqualifyforthesystem,thelinelengthislarger,theinfluenceofsuchfactorsasthefaultlinezerosequencecurrentwithallnonfaultlinezerosequencecurrentrelationshipismorecomplicated.Byanalyzingtheadvantagesanddisadvantagesofavarietyoflineselectionmethod,thispaperfinallychosethesignalinjectionmethod.Analyzedtheinjectedsignalpositioningmethodoflineselectionprinciple,andpointsoutthatthesignalinjectionmethodisessentiallyartificiallyincreasedthezerosequencecurrent.Injectedsignaldetectionmethodisdiscussed,andputforwardwiththezerosequencecurrenttransformerdetectionsignalinjectionmethod.Influenceinjectionsignalcurrentisanalyzedintheflowoffactorsinthefaultlineandphasecharacteristicsofthesignalcurrentinjection,pointsoutthatthephasecharacteristicsofthesignalcurrentinjectioncanonlyasanaidintheIIIcriterionoflineselection.KeywordsThesmallcurrentgroundingsystem;Singlegroundfault;Faultlocation;SignalinjectionIV目录摘要..............................................................................................................IAbstract...............................................................................................................II第1章绪论........................................................................................................11.1研究目的及意义.......................................................................................11.2国内外技术现状.......................................................................................11.3本文主要研究内容...................................................................................3第2章小电流接地系统的单相接地故障的电气特征分析............................42.1小电流接地系统.......................................................................................42.2中性点不接地单相接地故障的电气特征...............................................42.3中性点经消弧线圈接地单相接地故障电气特征...................................72.4本章小结...................................................................................................9第3章接地选线技术综述..............................................................................103.1利用稳态信号的接地选线技术.............................................................103.1.1零序电流幅值比较法......................................................................103.1.2零序电流方向法..............................................................................103.1.3谐波法..............................................................................................113.1.4零序电流有功分量法......................................................................113.1.5负序电流法......................................................................................123.1.6注入信号法......................................................................................123.2利用暂态信号的接地选线技术.............................................................123.2.1幅值与极性比较法..........................................................................133.2.2小波法..............................................................................................143.2.3暂态能量法......................................................................................143.3本章小结.................................................................................................14第4章信号注入法..........................................................................................154.1注入信号法的提出.................................................................................154.1.1“S注入法”的提出..........................................................................154.1.2从中性点注入信号法的提出..........................................................184.2注入信号源.............................................................................................204.2.1信号源及其功率................................................