同塔四回线路单相接地故障距离保护

Distance protection for single-phase grounding fault of four-loop transmission lines on same tower

针对同塔四回平行线路零序互感在单相接地故障时对距离保护的影响,提出一种基于单回线路单端信息量的距离保护算法。该算法通过建立四回线路零序阻抗矩阵来分析零序回路特征,综合考虑了系统零序阻抗变化和线路零序阻抗的影响,利用非故障线路与故障线路零序电流比值代替非故障线路零序电流,以此消除线路耦合对整定的影响。仿真结果表明,所提算法在线路发生单相接地故障时,能够保证距离保护正确动作,优于基于单回线路电气量的传统距离保护算法。

According to the impact of the zero-sequence mutual inductance of four-loop parallel transmission lines on the same tower on the distance protection during single-phase grounding fault,a distance protection algorithm based on the single-end information of one loop is proposed,which analyzes the characteristics of zero-sequence loop by establishing a zero-sequence impedance matrix of four-loop transmission lines,considers comprehensively the variation of system zero-sequence impedance and the influence of line zero-sequence impedance,and replaces the zero-sequence current ratio of healthy line by the zero-sequence current ratio of healthy line over faulty line to eliminate the effect of line coupling on the settings. The simulative results show that,better than the traditional distance protection based on single-loop information,the proposed algorithm can guarantee the proper operation of distance protection during single-phase grounding fault.