基于暂态相电流的小电流接地故障定位研究

Earth fault location based on transient phase current in non-solidly earthed network

提出一种利用三相电流中的故障电流暂态分量实现小电流接地故障定位的新方法。故障点上游线路,故障相的故障电流暂态分量约等于3倍的上游暂态零模电流,方向为由故障点流向母线;而健全相的故障电流暂态分量约等于故障点下游暂态零模电流,且由母线流向故障点。故障点下游线路,故障相和健全相的故障电流暂态分量均约等于下游暂态零模电流,方向为由故障点流向负荷。在此基础上,定义和求取方向参数,根据故障点两侧方向参数的不同实现故障定位。该方法只需本检测点的三相电流信号,不需电压信号,也不需相邻检测点时钟精确同步。

On the basis of analyzing the transient characteristics of three phase current in single-phase earth fault, a new method for fault location based on transient phase current is proposed. Before the fault point, the transient fault phase current is three times of the zero module current, and it flows from fault point to the bus. While the transient sound phase current is approximately equal to the transient zero module current after the fault point and it flows from the bus to the load. After the fault point, the fault and sound phase current are all approximately equal to the transient zero module current, and the direction is from the fault point to the load. According to the above characteristics, direction parameters can be defined to locate the fault section with the difference before and after the fault point, This method only uses three phase current. The voltage signals and the accurate time synchronization of different detection point are not necessary.