基于广义S变换能量相对熵的小电流接地系统故障区段定位方法

摘要

Single-phase earth fault occurs in small current neutral grounding system,which generates relatively abundant electrical transient characteristic.Transient zero sequence currents on both sides of the healthy section have high similarity,while both sides of the fault section show a great discrepancy.Thus,a fault section location method based on energy relative entropy of generalized S-transform is proposed.First,taken transient zero sequence current as fault feature,the starting time of the various detection devices to upload data is determined by the zero sequence current fault component.Thereafter,the generalized S-transform for the transient zero sequence current uploaded by various devices on feeders is carried out,and then the time-frequency matrix is obtained.Finally,the difference between the signals on both sides of various sections is represented by energy relative entropy.Through calculation and comparison,the section of maximum entropy is fault section.This method is suitable for different fault positions,fault angles and transition resistances.Simulation results verify the proposed method.%小电流接地系统发生单相接地故障后,系统中产生特征较为丰富的电气暂态量.针对健全区段两端的暂态零序电流相似度高,而故障区段两端暂态零序电流差异较大的特点,提出一种基于暂态零序电流的广义S变换能量相对熵的故障区段定位方法.首先,以暂态零序电流作为故障特征量,根据零序电流突变量确定各检测装置上传数据的起始时刻.然后,对馈线上各装置上传的暂态零序电流进行广义S变换,得到其时频矩阵.最后,利用能量相对熵表征各区段两端信号的差异,通过计算比较,确定熵值最大的区段为故障区段.该区段定位方法适用于不同故障点位置、不同故障角、不同过渡电阻情形下的故障定位,仿真结果验证了所提方法的有效性.