小电流接地电网单相接地故障的暂态特性  

Transient Characteristics of Single-phase-to-ground Fault in the Indirectly Earthed Power System

作　　者：唐轶[1] 陈奎[1] 陈庆[1] 

机构地区：[1]中国矿业大学,徐州221008

出　　处：《高电压技术》2007年第11期175-179,共5页High Voltage Engineering

基　　金：中国矿业大学青年科研基金(2005A010)

摘　　要：针对小电流接地系统单相接地故障接地选线困难的问题,通过理论分析、仿真研究和大量6kV模拟实验验证,深入研究了该型故障的特征,着重研究了电弧接地故障时暂态零序测量电流的特征,以及故障线路与非故障线路暂态零序测量电流之间的关系。结果表明:①电弧接地时,零序电压和各馈线零序电流中都有高频衰减的暂态分量。暂态分量的频率主要与变压器漏抗、电网对地电容和相间电容有关,频率约在0.3～3kHz之间。暂态分量的特征基本不受中性点接地方式的影响。②故障线路与非故障线路的暂态零序电流在频率、衰减速度等特性上相同。非故障线路暂态零序电流的大小与本线路对地电容的大小成正比,而故障线路暂态零序电流等于所有非故障线路暂态零序电流之和,但方向相反。③单相接地故障发生在相电压最大值附近时暂态零序电流最大,发生在相电压过零点附近时最小;暂态零序电流的衰减速度随电弧电阻的增大而加快。这些暂态特性可为研究基于单相接地故障暂态分析的接地选线方法提供理论依据。Through theoretical and simulation analyses and the verification of lots of simulating experiments in 6 kV power network, the transient characteristics of single-phase-to-ground fault in the indirectly earthed power system are deeply studied. And the characteristics and relation between transient zero-sequence measurement current in arcearth fault of fault feeder and non-fault feeder are emphatically studied as follows： ①When the arc is grounding, there is already the high frequency attenuation transient component in the zero-sequence voltage and zero-sequence current, the frequency of transient component is mainly relevant to the leakage impedance of transformer, to-earth capacitances of power network and capacitances between phases, the frequency is about 0.3 - 3 kHz . The characteristic of transient component is basically not influenced by the earth patterns at neutral point; ②The zero-sequence transient currents of non-fault feeder and fault feeder are equal in frequency, attenuation speed and so on. The zerosequence transient current intensity of non-fault feeder is directly proportional to the to-earth capacitance of this feeder, however, the zero-sequence transient current of the fault feeder is equal to sum of zero-sequence transient current in all non-fault feeders, but the direction is opposite; ③As the single-phase earth fault occurs nearby the maximum value of phase voltage, the zero-sequence transient current is the most intensive, and it is smallest nearby passing the zero point. The attenuation velocity of the zero-sequence transient current speeds up with increase of arc resistance. These transient characteristics can provide the theoretical foundation for studying the detecting singlephase-to-ground fault methods.

关 键 词：配电网 暂态 电弧接地故障 小电流接地电网 小电流接地选线 单相接地故障 

分 类 号：TM86[电气工程—高电压与绝缘技术]