一种考虑不同期合闸的行波合闸保护新方法

Novel Method of Closing Protection Considering Breakers Asynchronous Closure Based on Travelling Wave

当线路末端故障时,行波在线路末端的反射情况比较复杂,反向电流行波的极性有可能与正向电流行波的极性相反,而此时测距结果又与线路无故障时相同。因此,会造成行波测距式与行波极性比较式合闸保护的不正确动作。根据行波的折、反射理论,分析出当线路无故障时正向电流行波仅在线路末端发生反射,且电流行波的反射系数为-1,而当线路存在故障时,正向电流行波将在故障点发生反射,无论故障是否在线路末端,电流行波的反射系数都不会是-1。根据这一特征,提出了一种新的行波合闸保护方法。从原理上保证了在各种情况下保护都可以正确动作,大量的电磁暂态仿真结果也证明了这一点。

If there are faults at the terminal of the lines, and backward current traveling wave is different. Under the reflection of traveling wave is complex and the polarity of forward this condition, the fault location results of faulted lines and fault-free lines are the same. Therefore, the protections based on polarity comparison and traveling wave fault location will mal-operate. According to the theory of traveling wave reflection and refraction, if a transmission line is faul^free, the forward traveling wave will be reflected only at the terminal of line and the reflect coefficient of current traveling wave is -- 1. Whereas the forward traveling wave will be reflected at the fault point when switching onto the faulted line, and the reflect coefficient of current traveling wave is not equal to -1 no matter whether the fault is at the middle or the terminal of the line. Based on the theory described above, a new closing protection is presented. The principle of proposed protection can ensure that the relays will operate correctly in any case, and the results of tests show that this method is reliable and effective.