配电系统接地故障检测的一种新算法

A new method of earth fault detection in distribution system

针对小电流接地系统中单相接地选线的方法,提出了一种新的适用于中性点不接地或非直接接地配电网系统的接地故障检测算法。该方法是基于故障时由暂态电压零模量和暂态电流零模量计算而得到的暂态阻抗,其中暂态电压零模量和暂态电流零模量是在暂态主周期计算而得。然后根据暂态阻抗计算出的接地电容来实现接地故障的检测。利用Matlab/Simulink进行了仿真,并模拟了三种不同故障条件下的仿真过程,结果验证了该方法的可行性。最后阐述了测量误差减小的方法以及判定故障的整定值的确定。

This paper proposes a new algorithm of earth fault detection in neutral unearthed （isolated） or compensated networks of distribution system. This method is based on transient impedance, which is calculated from transient voltage earth modes and transient current earth modes when fault occurs. The values of voltage earth modes and transient current earth modes are calculated in the period of the dominant transient frequency. Then the earth capacitance calculated from transient impedance gives an indication about whether the feeder is faulted or not. The network is simulated by Matlab/Simulink and three different fault conditions are presented in this paper.The results prove that the method is feasible. At last, a method is proposed to avoid the errors and the setting about whether the feeder is faulted or not is determined.