消除零模波速影响的配电网单端行波故障测距算法

配电网线路分支众多，末端往往具有三相不平衡负载，传统的单端行波法需在复杂的折反射波中提取故障点的反射波，不易实现。而基于模量行波速度差和基于线模行波突变这两种故障测距方法的精确度都受制于不稳定的零模波速度。基于此，将两种方法结合，利用零模检测波速度与传播距离成对应关系的特点，获得不受零模波速度影响的故障定位新方法，该方法避免了传统故障测距算法需要多次从复杂的折反射波中提取信息的缺点，能够简洁、快速、准确地对复杂的分支线路进行故障测距。此方法首先检测故障暂态行波的零模和线模分量到达首端的时间差，然后在首端对三相同时注入相同的高压脉冲并检测线模行波首个波头到达检测点的时间，进而利用稳定的线模波速度进行故障距离的测量。最后，利用PSCAD仿真验证了所提方法基本不受故障位置、过渡电阻大小以及故障初相角的影响，各种情况下绝对误差均在100 m之内。

A single-terminal fault location algorithm in distribution network for eliminating the effect of the velocity of zero-mode traveling wave

Due to frequently occurred three-phase unbalanced loads in the ends of large number of branches in distribution networks, it is difficult to extract reflected wave of the fault point in the complex reflected and refracted waves using the traditional single-terminal traveling wave methods. Simultaneously the precision of the fault location methods based on the difference of wave velocity between zero-mode component and line-mode component of traveling waves and the one based on mutation of line-mode traveling wave are decided by the unstable zero-mode wave velocity. Therefore, a new approach is proposed by combining the above two methods to achieve higher efficiency and precision of measuring the fault distance and location. The presented method employs the correspondence between the detected zero-mode wave velocity and the fault distance to achieve the fault location algorithm which is not impacted by zero-mode wave velocity. The approach firstly detects difference of arrival time between the zero-mode traveling wave and line-mode traveling wave at the head end. And then post-injecting high voltage pulses into three phases simultaneously and detecting the arrival time of the first line-mode traveling wave head at the head end of the transmission line. Following, it employs the stable line-mode wave velocity to execute the measurement of the fault distance. Finally, PSCAD-based simulation shows that the absolute errors of this algorithm are less than 100 m in all cases, without influence from the fault location, grounding resistance and fault initial phase angle. This work is supported by National Natural Science Foundation of China (No. 51407121).