输电线路不同期合闸操作的行波特征分析

针对目前合闸到故障的行波识别方法还不够完善的现状，对线路不同期合闸引起的行波特征进行了分析。通过求解故障点的等值波阻抗，得到了故障点各模量行波之间相互透射的透射系数以及各个模量行波反射系数的计算方法。在此基础上，对线路不同位置、不同过渡电阻、不同合闸顺序情况下引起的行波特征进行了分析。结果表明:当线路中部故障时反向初始电流行波的极性与正向电流行波的相同，但当线路末端故障时，反向初始电流行波的极性与正向电流行波的极性关系受故障类型、过渡电阻大小以及故障相是否先合等因素的影响，在某些情况下会出现反向初始电流行波的极性与正向行波的极性相反的情况，这与线路无故障时合闸的极性关系相同，造成现有的识别方法失效。该结果为合闸到故障行波识别方法的研究夯实了行波理论的基础。

Characteristics of Travelling Waves Caused by Breakers Asynchronous Closing

Since protection identification methods based on travelling waves for switch onto faulted line are imperfect, the paper analyzes the characteristics of travelling waves caused by breakers asynchronous closing. By computing wave impedance at trouble spots, the approach to calculate the reflection coefficient and the inter-refraction coefficient of every mode is obtained. Based on the approach, the characteristics of travelling waves caused by breakers asynchronous closing in the cases of different trouble spots, different transient resistance and different closing sequence of three-phase breakers are investigated. The results show that forward travelling waves have the same polarity as backward travelling waves if faults at the middle of lines. However, if faults at the end of lines, the polarity relations between forward travelling waves and backward travelling waves depend on fault type, transient resistance and trouble phase closed first or not. In some cases, the polarity of forward travelling waves is different from that of backward travelling waves. Thus, the polarity relations are the same with those caused by closing unload lines. As a result, the existing methods will be invalid. Therefore, this paper will help to the further development of travelling wave protection identification methods for switch onto faulted line.