数字通信电流保护在地铁中压网络零序电流保护的应用

Application of Digital Communication Current Protection in Zero-Sequence Current Protection of the Metro’s MV Network

地铁工程中压环网供电方式采用传统零序电流保护配合很难,数字通信电流保护在地铁工程中压网络零序电流保护中的应用,解决了零序电流保护配合的问题;通过零序电流保护误跳的实际案例,分析单相接地故障时线路电容电流的变化,证明线路电容电流等于正常时三相线路电容电流的代数和。介绍零序电流保护整定方法,并指出作为相邻元件的后备保护,可将站间的电缆电阻作为接地电阻来校验灵敏度。

It is difficult to cooperate with the traditional zero-sequence current protection of the metro’s MV ring powersupply net.This paper introduces the application of digital communication current protection in zero-sequence current protection of the metro’s MV network,which solves issues relating to the cooperation of zero-sequence current protection.The variation of cable capacitive current when a single phase earthing fault occurs is analyzed through an actual case of false tripping of the zero-sequence current protection,proving that the line capacitive current is equal to the algebraic sum of the three-phase line capacitive current in normal conditions and thus clarifying the setting method.It is further demonstrated that as a backup protection of adjacent components,the cable resistance between substations can be used as the grounding resistance in order to verify the sensitivity.