基于零序电流包络线拟合斜率的配电网故障选线方法

A distribution network fault line selection method based on zero-sequence current envelope fitting slope

配电网发生高阻接地故障时,传统的选线方法可靠性不高。对健全线路与故障线路在高阻接地条件下暂态零序电流的差异性进行分析,发现健全线路与故障线路的暂态零序电流趋势不同,两者对应趋势的斜率正负相反。因此提出了一种基于暂态零序电流包络线拟合斜率的故障选线方法。首先对暂态零序电流利用牛顿插值算法求取包络线;然后通过可变遗忘因子递推最小二乘法计算各条线路的拟合斜率,利用健全线路与故障线路包络线拟合斜率值正负相反的特点构建出选线判据;最后大量仿真结果表明:提出的选线方法适用于各种故障条件。

When a high-resistance ground fault occurs in the distribution network,the traditional route selection method is not sufficiently reliable.The difference of transient zero-sequence current under the condition of high resistance grounding while between the normal operated and fault lines is analyzed.The major difference is that the slopes of the corresponding trends of those two types of current are opposite.Therefore,a fault line selection method based on the slope of transient zero-sequence current envelope curve fitting is proposed.Firstly,the envelope curve of the transient zero-sequence current is obtained by the Newton interpolation algorithm,and then the fitting slope of each curve is calculated by the variable forgetting factor recursive least square method,and the resulting positive and negative characteristics of the slope values fitted by the envelope curves of the operating and the fault line can be utilized to construct the proposed fault line selection criterion.A large number of simulation results show that the route selection method proposed in this paper is suitable for various fault conditions.