一种新的相间行波距离保护方法

当对端母线上仅有1回进出线时，行波保护确定故障为正方向就可以动作；当对端母线上有2回进出线时，区外故障的行波测距结果大于被保护线路长度，根据测距结果，行波保护可以容易地区分区内、区外故障。当对端母线上有3回及以上进出线时，行波测距结果在某些情况下不反应故障点到保护安装处的距离，不能用测距结果区分区内、区外故障。对于这种情况，文中首先给出了根据行波测距结果和行波波头计算故障过渡电阻的方法，然后对区内、区外故障测得的过渡电阻进行分析，表明区内、区外故障测得的过渡电阻有很大不同，据此提出了一种区分区内、区外两相故障的方法。大量电磁暂态仿真表明，该保护原理正确而且适用于三相故障。

A NEW DISTANCE PROTECTION SCHEME BASED ON TRAVELLING WAVE FAULT LOCATION

If there is only one line on the far terminal bus, travelling wave protection will operate after detecting the fault is forward. If there are two lines on the far terminal bus, the results of travelling wave fault location are longer than the length of protected line under condition of out area faults. According to the results of fault location, protection can distinguish in area faults from out area faults easily. If there are more than two lines on the far terminal bus, the results of fault location are not the distance between fault point and protection in some condition. For this case, a calculating transient resistance method using results of fault location and initial travelling wave is proposed at beginning, then the difference of transient resistance measured by protection is analyzed in the condition of in area faults and out area faults. Based on the difference, a scheme for distinguishing in area from out area two phase faults is presented. The simulation results show the schemes are correct and can be used for three phase faults.