基于两相电流行波的接地选线方法

中性点非有效接地配电系统大多只安装两相电流互感器,其接地选线问题是长期困扰实际运行的技术难题。为了解决只装有两相电流互感器配电系统的单相接地选线问题,在分析了中性点非有效接地配电系统接地所产生的电流行波特征的基础上,提出了基于两相初始电流行波和小波变换的接地选线新算法。该算法仅仅利用接地时所产生的两相行波,不受中性点接地方式和系统正常运行时不平衡电流的影响,解决了现场的实际运行需要。仿真和试验结果验证了所提出的方法的可靠性和有效性。

Fault Line Selection Based on Two-phase Current Traveling Wave

There are only two-phase current transformers (CTs) installed in most of distribution system with neutral non-effective grounding (NNG). It has been a very difficult problem for protective relay engineers for a long time to identify faulted line, when single phase to ground fault (SGF) occurs. In order to identify the fault line in the distribution system with only two-phase CTs, the transient traveling wave resulted from SGF is analyzed, then a new algorithm of fault line selection based on both only two-phase current traveling wave and wavelet transform is presented in this paper. The algorithm is independent of the mode of neutral grounding and the unbalanced current under normal operation condition. It can satisfy the requirement of fault line selection in field operation. The simulations and experiments verify the validity and reliability of the proposed algorithm.