雷击与短路故障的S变换特征量识别方法

雷击与短路故障的S 变换特征量识别方法

肖先勇1,李　逢1,邓武军2

(1.四川大学电气信息学院,成都610065;2.宜宾电业局,宜宾644002)

摘　要:输电线路落雷后雷电冲击干扰超高速保护动作。基于行波特征区分雷电冲击与短路故障有一定局限性,提出一种利用母线电压信号特征识别雷击与短路故障的新方法。以IEEE RB TS 26标准测试系统为仿真对象,对不同雷击情况以及短路故障进行了仿真,验证了该算法的正确性和有效性。检测到的母线电压进行S 变换,提取S 变换时频等值线和幅值包络向量,根据是否含高频分量和等值包络向量的修正一阶中心矩的正负,直观准确地实现类型识别,并对特征提取和识别算法进行研究。它利用现有电能质量监测装置检测的信号进行识别,为通过母线电压波形辨识雷电冲击与短路故障提供了新方法。

关键词:故障类型;识别方法;母线电压;S 变换;高频分量;修正一阶中心矩中图分类号:TM835;TM863文献标志码:A 文章编号:100326520(2009)0420817206

基金资助项目:国家自然科学基金(50677041);四川省应用基础研究项目(2008J Y004322)。

Project Supported by National Natural Science Foundation of China (50677041),Science and Technology Bureau of Sichuan Prov 2ince (2008J Y004322).

Identif ication Method of Lightning Stroke and Short 2circuit

F aults Using S 2transformed Characteristics

XIAO Xian 2yong 1,L I Feng 1,DEN G Wu 2jun 2

(1.School of Elect rical Engineering and Information ,Sichuan University ,Chengdu 610065,China ;

2.Yibin Elect ric Power Bureau ,Y ibin 644002,China )

Abstract :The ultra 2high 2speed protection of the power transmission system may be interfered by lightning strokes on lines.It is limited to distinguish the lightning stroke and the common short circuit fault based on the current trav 2eling 2waves.We proposed a new method to distinguish the lightning strikes and common short 2circuit faults on the basis of the characteristic of the bus voltage signals using S 2transform.Through extracting the feature of the voltage signal using time 2f requency contour and amplitude envelope vectors by S 2transform ,an idiographic method for iden 2tification of the three types of transient processes was proposed.I f there is high f requency component in the voltage signal ,the transient process is caused by lightning stroke.If the modified first order central moment B F <0,there is fault ,and if B F >0there is not fault.According to the S 2transformed characteristic of bus voltage the different tran 2sient type can be identified exactly.The methods of both feature extracting and recognition algorithm were proposed also.The IEEE RB TS 26as the standard testing system was used to illuminate the run 2of 2mill principle through the PSCAD/EM TDC.The simulation results indicate that the proposed method is effective with reasonable accuracy and its accuracy is not affected by fault types ,transient resistance condition and fault location.The instrument of the power quality can be equipped on the system to evaluate the wave of the bus voltage ,this paper provide the basic theory to distinguish the lightning strikes and the short 2circuit fault through the voltage wave observed f rom the power quality instrument.

K ey w ords :fault types ;identification method ;bus voltage ;S 2transform ;high f requency component ;first order cen 2tral moment

0　引言

输电线路距离长,雷击几率高。线路保护中,基于行波和暂态量的超高速保护应用广泛。这些基于故障暂态信号的保护,不可避免地会受到各种高频信号的干扰[1]。雷击输电线路时产生的行波在系统

中传递,含有大量高频分量。从线路落雷到跳闸,雷电流必须超过线路耐雷水平,绝缘发生冲击闪络,只有当沿闪络通道流过的工频短路电流的电弧持续燃烧时,线路才会跳闸。若工频电弧熄灭,或是感应雷击,不会造成短路故障,但含有高频分量,可能影响超高速保护动作,因此有必要区分雷电冲击与故障。现有雷电冲击与故障识别[127],大多基于雷电行波特征,采用不同监测识别方法提取行波电流特征以区分雷电冲击与故障。有一定的局限性且需装设专门的行波检测装置。

线路落雷后雷电波不仅会影响线路两端,也会

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718・ 第35卷第4期

2009年 4月

高　电　压　技　术

High Voltage Engineering

Vol.35No.4

Apr.　2009