基于小波相对熵的变电站直流系统接地故障定位方法

Location Method of Ground Fault in DC System of Substation Based on Wavelet Relative Entropy

变电站直流系统的状态直接关系到变电站的正常运行,为了对变电站直流系统出现的接地故障迅速定位,提出了一种基于小波相对熵的直流系统接地故障定位新方法。该方法首先应用小波包变换对直流系统各支路的漏电流进行分解,然后引入小波相对熵理论,以直流系统正常运行情况下,从各支路采集到的漏电流的频谱特性为参照序列,计算直流系统发生接地故障时各支路的小波相对熵,最大小波相对熵对应的支路即被定位为发生接地故障的支路。然后在PLECS软件中搭建模型进行仿真试验,仿真结果表明,该方法能够准确定位变电站直流系统出现的接地故障,同时对于绝缘性能有所降低的变电站直流系统也有着良好的适用性。

The state of DC system of substation is directly related to the normal operation of substation.To locate theground fault occurred in the DC system of substation rapidly,a new method to locate ground fault based on waveletrelative entropy is proposed in this paper.This method firstly decomposes the leakage current of each branch of theDC system though wavelet packet transform,and introduces theory of wavelet relative entropy.Then,the relative en-tropy of each branch is calculated when the ground fault occurs in the DC system with the spectral characteristics ofthe leakage current collected from each branch at normal operation condition as the reference sequence.And theground fault is considered to occur in the branch which has maximal wavelet relative entropy.Build a simulation mod-el in the PLECS software and make simulation.The simulation results show that the new location method for groundfault which is suitable for both of DC systems with good insulation performance or bad insulation performance.