小电流接地系统单相接地故障测距的研究——基于改进A型行波法

Research on single phase grounding fault location of small current grounding system——based on improved A type traveling wave method

反向行波首次到达母线引起突变的模极大值极性与正向行波的相反,且在所有反极性模极大值中幅值最大、易于识别。对传统的A型行波法进行了改进,提出了综合利用不同极性的正向行波和反向行波进行故障测距的新方法,该方法有效地解决了传统的A型行波法存在的行波干扰问题。该方法以故障初始行波到达母线引起突变的幅值最大的正极性模极大值对应的时间作为故障测距的计时起点,并自动判断故障点位于故障线路的前半部分还是后半部分从而选择合适的计时终点。当故障点在线路的前半部分时,以故障点反射波到达母线引起突变的正极性模极大值对应的时间作为计时终点。当故障点位于线路的后半部分时,以线路对端反射波到达母线引起突变的负极性模极大值对应的时间作为计时终点。通过Matlab仿真实验验证了该方法的可行性,同时也证明了该方法具有一定的抗过渡电阻能力、不受中性点接地方式的影响。

When the negative traveling wave firstly arrives in bus, maximum modulus polarity of abrupt change is opposite to positive traveling wave. In all the reverse polarity maximum modulus, its amplitude is largest and easy to recognize. The traditional A type traveling wave method was improved, proposing a new fault location method with the comprehensive utilization of different polarity positive and negative traveling wave. This method effectively solve traveling wave interference problem in the traditional A type traveling wave method. This method took the time when initial wave arrives in the bus line and positive modulus of maximum amplitude of abrupt change are maximum, as fault location timing starting point. This method automatically judges fault point, which locates in the front half of the fault line or latter half part, choosing the right timing terminal. When the fault point is in the front half part, it takes the time when reflection waves of fault point reach bus as timing terminal. When the fault point is in the latter part, it takes the time when reflection waves of line to end reach bus as timing terminal. The Matlab simulation experiments prove the feasibility of this method, and prove that this method has a certain anti-transition resistance ability and isn＇t affected by neutral point grounding way.