在配电网中发生单相接地故障时不借助电压互感器计算残余电压角度的方法

A method to compute residual voltage angle without voltage transformers during single phase earth fault in distribution network

在配电网中发生单相接地故障时,为了判定故障的方向,仅仅利用电流判据经常是不够的。如果能够得到残余电压的角度信息,再配合电流判据一起使用,就能够得到比较准确的结果。鉴于安装电压互感器的额外成本,配电网线路中往往只安装电流互感器。于是,基于带电指示器的低成本和可以获得电压角度的特性,提出了一种利用带电指示器来估算残余电压角度的方法。首先针对各种中性点接地的配电网进行归类,然后提出各自的计算方法。经过EMTP/ATP和Matlab协同仿真验证表明,获得的残余电压角度用于单相接地故障定位有良好的精度。值得一提的是本方法同样适用于带有分布式电源的配电网。

During single phase earth faults in distribution networks it is often insufficient to use current information only to perform directional fault detection. If the residual voltage angle is also available, the fault direction can be identified more easily. Due to the additional cost of voltage transformers they are often not available in distribution networks. This paper presents a method to estimate residual voltage angle with low-cost voltage presence indication system. The distribution networks are classified into groups according to their neutral earthing types. Different calculation methods are given for each group. The calculation methods have been validated by co-simulation with EMTP/ATP and MATLAB. The result shows that directional fault detection of single phase earth fault with the estimated residual voltage angle can achieve a promising accuracy. This method can also be applied in distribution networks with distributed energy resources.