基于方向行波能量的小电流接地系统故障选线方法

Fault Line Selection Method for Small Current Grounding System Based on Directional Traveling Wave Energy

现有行波选线方法易受到高阻接地、行波全反射、噪声及其他恶劣接地条件的影响,存在灵敏度和准确度不高的问题。据此提出一种利用故障电流方向行波能量的配电线路接地选线方法。该方法选取各线路一定数据窗的暂态零序方向电流波形,对其经小波分解得到相应频带系数,利用所得系数和波阻抗的组合可求得各线路方向行波能量,根据方向行波能量的大小关系合理地构造判据表达式,充分利用故障信息,最大限度地放大故障支路与健全支路的区分度,使得故障线路可靠识别。理论分析、仿真和实测结果均表明,该选线方法对选线的灵敏度和准确度有较大提升。

Existing traveling wave line selection methods are easily affected by high-resistance grounding,traveling wave total reflection,noise,and other harsh grounding conditions,so it has defect of low sensitivity and accuracy.Accordingly,propose a new method of grounding line selection for distribution lines by using the energy of the fault current direction traveling wave.This method,by selecting the transient zero-sequence directional current waveform of a certain data window of each line,obtains the corresponding frequency band coefficient through wavelet decomposition,the combination of the obtained coefficient and the wave impedance can be used to obtain the directional traveling wave energy in each line,the size relationship is reasonable to construct the criterion expression,the fault information is fully utilized,and the distinction between the faulty branch and the healthy branch is maximized,the fault line can be identified reliably.According to theoretical analysis,simulation and actual measurement results,this method increases the application range of the traveling wave line selection method,the sensitivity and accuracy of line selection are greatly improved by this method.