基于负序电流的配电网单相接地故障选线方法的研究

Study on the method of faulted feeder determination for single-phase grounding fault in distribution networks Based on negative sequence currents

利用故障后系统中的负序电流进行单相接地故障选线的方法相对于基于故障后零序电流的选线方法有其优越性。提出用微分和积分移相提取负序电流,比较用移点法、微分法、积分法移相提取负序电流的优缺点,并利用提取得到的负序电流实时曲线进行故障选线。利用实时曲线故障后波形与故障前波形对应相减可以减小不平衡电流的影响,利用此差值电流中的暂态分量和工频分量,可以达到选取故障线路的目的。仿真分析结果表明,该方法在系统中存在不平衡电流等情况下都能可靠选出故障线路。

The algorithm based on the negative sequence currents for tault Line selection has its advantages than that based on the zero sequence currents when singly-phase-to-earth fault happens. The method of acquiring negative currents by shifting phases using differential and integration methods is proposed, and comparison is made for the advantages and disadvantages among the point shifting method, the differential method and the integration method. The ac quired negative currents are used to select the fault line. The corresponding subtraction of the pre-fault currents from the fault currents in the real-time curve is used to reduce the impacts of unbalanced currents. The transient component and the power frequency component in the corresponding subtraction can help to select the fault line. Simulation results show that the aforementioned method can select the fault line reliably even there are unbalanced currents in the system.