基于希尔伯特-黄变换的小电流接地故障选线研究

在非有效接地电网中，单相接地故障发生概率最高，对系统造成的威胁最大。由于单相接地故障电容电流数值较小，故障信号信噪偏低，增大了选线难度，特别是经消弧线圈接地方式下，其接地电流更小，因此小电流接地系统单相接地故障选线问题多年来一直未能得到很好的解决。文章引入信号处理方法希尔伯特-黄变换对故障特征量进行模态分解和希尔伯特变换，比较其高频分量的一阶差分方向从而判断故障线路；并使用MATLAB软件搭建模型，模拟单相接地故障，通过对暂态零序电流分量信号进行处理，得到方向相反的故障线路，依据仿真结果验证了该方法的准确性和有效性。

Application of Improved Grey--Clustering Entropy Method to Transformer Fault Diagnosis

In non-solidly ground system, single-phase earth fault occurs in the highest probability and also causes the most danger for the system. The capacitive current and signal noise are both small, which make the fault line selection much more difficult, especially when ground current （grounded through Petersen-oil） is too small. The problem of fault line detection has not been solved perfectly for many years. This article uses MATLAB which build distribution network system model and simulate the single-phase earth fault. After processing the transient zero sequence current signal, the fault line which has the different polarity with other lines finally is shown. At last, the simulation results show the practicality and effectiveness of HHT, especially on processing signal which occurs during the transient fault course.