基于零序电流差暂态小波能量的故障选线新方法

摘要

A novel fault line selection method which based on transient wavelet energy of difference zero sequence current was proposed in this paper.Firstly, the difference zero sequence current (DZSC) was obtained by subtraction between each feeder.Then, the wavelet high-frequency detail coefficients of the DZSC which under each decomposition level were calculated, and the transient energy was acquired in the slide window.Furthermore, the DZSC energy of each feeder and all feeders were calculated under 3-5 decomposition levels.The best decomposition level could be found by comparing the value of all feeders′energy, so the proportion of each feeder′s energy under all feeders′energy based on the best decomposition level could be calculated.Lastly, the fault line was selected by comparing the property with the given threshold.The proposed method not only immuned from the influence of compensation degree, fault location, phase angle, load, and fault transient résistance, but also had higher accuracy, sensitivity and strong anti-interference ability.The simulation results verified the effectiveness of proposed method.%提出一种基于暂态零序电流差能量比较的小电流接地系统单相接地故障选线方法.该方法首先求取各馈线间零序电流的差, 并计算出每条馈线零序电流差的小波各尺度的高频细节系数, 获得滑动时间窗口内的暂态能量;然后在3～5层分解尺度下求取每条馈线零序差值能量和, 并计算出各分解尺度下所有馈线的能量总和, 比较各分解尺度下馈线零序电流差能量总和, 获得最佳分解尺度及最佳分解尺度下各馈线零序电流差能量所占的比重, 将其与整定阈值比较后得出故障线路.该方法不受消弧线圈补偿度、故障发生地点、故障的过渡电阻及相角的影响, 具有选线准确、灵敏度较高的特点, 抗干扰能力强.最后, 通过仿真试验验证了该方法的可行性和有效性.