小电流接地系统两点单相接地故障选线的研究

分析了小电流接地系统发生两点单相接地故障后零序电流的特征,在完善一点接地故障选线的基础上,提出了一种针对系统发生两点单相接地故障的选线方法,该方法主要利用线路发生两点接地故障时故障线路的暂态零序电流方向与所有非故障线路暂态零序的方向差异最大,母线故障时各线路暂态零序电流方向一致的特点进行第一次故障选线,当该故障线路被切除后,再利用故障线路的零序电流大于非故障线路的零序电流这一特点进行第二次故障选线。理论和大量Matlab仿真表明:该方法适合于各种接地方式的小电流接地系统一点或两点单相接地故障的选线,具有可

Research on fault line selection of single-phase grounding at two localities in power system with neutral unearthed

The paper analyzes the characteristics of zero-sequence current after single-phase grounding at two localities in power system with neutral unearthed. Based on the improvement of line selection of single-phase grounding at one locality, a method of fault line selection of single-phase grounding at two localities is presented. The method is to select the first line fault using the characteristics that the direction of transient zero-sequence current in the fault line are the most dissimilar to all non-fault lines when lines are fault, and the direction of transient zero-sequence current in all the lines are consistent when busbar fault occurs. It selects the second line fault by virtue of the character that zero-sequence current in fault line is stronger than that in non-fault lines after the first fault line is removed. Theoretical analysis and Matlab simulations show that the proposed method is suitable for various distribution systems with different grounding modes to select fault lines of single-phase earth faults at one or two localities. Moreover, it has a high reliability and strong anti-jamming ability.