基于暂态分量的配电网单相接地故障选线新方法

A novel method of fault line selection by transient component for single-phase to ground fault in distribution networks

关键词:  配电网  小波包  瞬时零序功率  单相接地故障

Key words:  distribution network  wavelet pocket  instantaneous zero sequence power  single-phase to ground fault

摘要:

在对目前应用小波变换技术进行配电网单相接地选线方法综合分析的基础上，提出了一种基于最小瞬时零序 功率的选线新方法。通过分析配电网单相接地故障的暂态过程，给出了配电网单相接地故障时零序电压和各条线 路的零序电流的瞬时表达式，定义了瞬时零序功率并将其作为故障选线特征量。结合配电网单相接地故障的大量 仿真分析，应用小波包将零序电流和零序电压暂态信号逐层剥离,提取最大分量的信号频段为特征频段;根据各线 路特征频带的零序电流、零序电压计算每条线路的瞬时零序功率，在短路第1个周期内,具有最小瞬时零序功率的线 路为故瘅线路。仿真分析结果表明,该选线方法对中性点不接地和中性点经消弧线圈接地配电网都适用,而且不受 短路时刻、线路长度的影响，抗电弧过渡电阻能力强。

Abstract:

The methods of fault line selection by wavelet transform wore summarized for single-phase to ground fault in distribution networks. Then a novel method of fault line selection was presented based on minimum instantaneous zero sequence power. By analyzing the transient process of single-phase to ground fault in distributiai networks, the expressiai of zero sequence voltage and zero sequence current was given. And instantaneous zero sequence power was defined and taken as characteristic quantity of fault line selection. The instantaneous zero sequence vdtage and currmt is deocmposed into many frequent bands by wavelet packet. The character frequent band is obtained by corr^)aring the value and the regulaticsn of instantaneous zero sequence voltage and current in each frequent band. The zero sequence instantaneous power of each line is calculated within first period of character frequent band. The fault line selection is implemented by comparing the minimum instantaneous ziero sequence power of each line. If its minimum instantaneous zero sequence power is least among all lines, the line is fault line It is avdded to corrpare the polarity of each line between zero sequence voltage and zero current. The new criteriai is adaptive to any type of neutral node oonnectiai in distribution networks. Smulation indicates that this novel selection fault line method exactly selects fault line in any time of short circuit with high value arc-resistance and with different length line.