小电流接地系统单相接地故障选线方法探究

Research on a method of fault line selection for single-phase earth fault in ineffectively grounded power systems

针对国内外小电流接地系统中单相接地保护方法,提出了一种新的基于零序电流高频幅值差的选线方法,形成新的选线判据。利用此选线判据可分别对故障线路和非故障线路加以权重,放大故障线路和非故障线路特性区别。采用小波变换对故障后各线路零序电流高频分量进行分析,依选线判据进行处理,从而获得各线路的权重。通过Matlab建立仿真模型,对不同情况进行模拟仿真实验,验证了此判据的正确性。

This paper puts forward a new single-phase earth fault line selection method based on the difference of zero-sequence high-frequency amplitude as line selection criterion.The new method is for the single-phase protection in ineffectively grounded power systems.With this method,weights is given to the fault line and the non-fault line respectively,and the characteristic difference between the fault line and the non-fault line is enlarged.This paper analyzes high-frequency amplitude after the fault line of the signal processed by wavelet transform,then processes them,thus gets the weight of each line.The validity of the criterion is testified with simulation experiments in various conditions.