基于图论的不接地系统在线故障定位方法

On-line Fault Location Method for Ungrounded System Based on Graph Theory

由于线路结构复杂、故障电流较小,配电网单相接地故障在线定位尚未得到完美解决。对不接地系统复杂配电线路进行单相接地故障零序网络分析,给出不同电源单独作用时故障后零序电流的相位特点。为减小零序电流测量误差的影响,引入图论中最小生长树的理论,以较大电流幅值测点为基础构建包含或临近故障点的子图,再以顶点距离综合顶点相位信息进行子图缩减,以准确确定故障区段边界。文中方法不受线路运行状态影响,降低了零序电流测量误差的影响,具有很强现场应用性,仿真算例表明该方法在较大测点相位信息准确的前提下便可实现可靠准确的故障定位。

Due to complex line structure and small fault current, the on-line location of single-phase grounding fault in distribution network are not perfectly solved. In this paper, the zero-sequence network of single-phase-to-ground fault for complex distribution lines in ungrounded system is analyzed, and the phase characteristics of zero-sequence fault current are given when different power sources act alone. In order to reduce the influence of zero sequence current measurement error, the theory of minimum growth tree in graph theory is introduced to construct sub-graphs containing or near fault points based on larger current amplitude measurement points, and then the sub-graphs are reduced by synthesizing vertex phase information with vertex distance to determine the fault section boundary accurately. This method is not affected by the operation state of the line and reduces the influence of zero sequence current measurement error, so it has great value on field application. Simulation results show that this method can achieve reliable and accurate fault location on the premise of accurate phase information of larger measuring points.