基于零序暂态电流方向判断的小电流接地选线方法

当非直接接地的配电网发生单相接地故障时，大部分情况下故障电流的稳态分量较小或为0，导致许多基于稳态分析的小电流接地选线装置的选线效果不理想。作者分析了6 kV模拟电网的大量实验数据，得到电弧接地故障时故障线路与非故障线路零序暂态电流的特征。在此基础上提出用各线路零序暂态电流相互点积积分平均值的正负来判断故障电流的方向，并采用一个时间段的积分平均值作为判断量，有效地提高了故障选线的准确性和可靠性。该方法计算量较小，能在单片机上实现，并具有在线纠错能力，对中性点不接地或经消弧线圈接地的电网均有效。

A Method of Single-Phase Grounded Feeder Detection in Indirectly Earthed Power System Based on Judging Zero-Sequence Transient Current Direction

When single-phase earth fault occurs in indirectly earthed distribution system, for most cases the steady state component of fault current is small or approximates to zero, it leads to insufficient faulty feeder detection that is based on steady state analysis. The authors analyze a lot of experimental data from the simulation of 6kV power network; obtain the features of zero-sequence transient currents in faulty feeder arcing fault and healthy feeders while arcing fault occurs. On this basis according to the sign of integral mean value of mutual dot products of zero-sequence transient currents of each two feeders, an approach to judge the direction of fault current is proposed, and the integral mean value during a time interval are taken as the judging quantity, thus the accuracy and reliability of faulty feeder detection can be effectively improved. The calculation amount of the proposed approach is smaller, so the operation can be implemented by single-chip microprocessor; besides, the proposed approach possesses online error correcting capability. This approach is effective for distribution network with ungrounded neutral or grounded neutral via arc suppression coil.