基于小波变换的串补输电线路故障选相研究

Study of fault phase selection for series compensated transmission lines based on wavelet transform

串补电容及其保护装置MOV的应用给常规的故障定位与选相方法带来了困难。然而,串补输电线路发生故障后以及故障期间MOV导通时将产生高频暂态电流行波,故障相和非故障相的暂态电流信号的大小及所含有的频率成分不同。本文采用小波分析方法,选择适当的小波函数与变换尺度对相电流进行小波变换,根据故障相和非故障相的暂态电流在此尺度上小波系数能量的差别,形成故障选相判据。大量的EMTP仿真结果证实了该方法的有效性。所提出的方法对串补超高压输电线路的故障定位与保护具有实际意义。

The application of series compensated capacitors and their MOVs cause difficulties for conventional methods of fault location and phase selection. However, high frequency transient currents will appear in the lines when a fault occurs and the MOV conducts. The fault phases differ from non-fault phases on the amplitudes and frequencies of the transient currents. In this paper, wavelet analysis method is used to analyse phase currents with the proper wavelet function and proper scale. The criteria of fault phase selection are made based on the differences in energies of wavelet coefficients of all phase currents. Plenty of EMTP simulations proved that the method is effective. The scheme given in this paper has practical value in the fault location and relay protection of series compensated transmission lines.