基于路图GFT谱相似度的小电流接地系统故障选线

Fault line selection of small current grounding system based on GFT spectral similarity of path graph

针对现有小电流接地系统发生单相接地故障时的选线问题,提出一种基于路图图傅里叶变换(GFT)谱相似度的故障选线方法。对各出线暂态零序电流进行路图GFT分析,发现非故障线路的路图GFT谱相似,与故障线路有明显差异。通过综合离散弗雷歇距离和综合余弦相似度2个维度综合表征故障线路和非故障线路的路图GFT谱差别,从而筛选出故障线路。仿真结果表明,所提方法实现简单,选线可靠性高,且不易受电网拓扑、过渡电阻、故障初始条件等因素的影响。

Aiming at the problem of line selection when a single-phase grounding fault occurs in the existing small current grounding system,a fault line selection method based on the graph Fourier transformation(GFT)spectrum similarity of path graph is proposed.The path graph GFT analysis of the transient zerosequence current of each outgoing line is carried out.The analytical results show that the spectral GFT of the path graph of the non-fault lines is similar while different from that of the fault line.The difference between GFT spectrum of the fault line and the non-fault line is comprehensively characterized by the synthetic discrete Fréchet distance and the synthetic cosine similarity,so as to screen out the fault line.The simulative results show that the proposed method is simple to implement,has high reliability of fault line selection,and is not easily affected by factors such as grid topology,transition resistance and initial fault conditions.