比相式母差保护保护死区的消除

母差保护在220 kV及以上电压等级的变电站中广泛应用,是一种不可缺少的重要保护。由于比相式母差保护需要根据母联电流的相位来确定故障母线,在两条母线发生相继故障时,存在一定的保护死区。基于母联电流比相式母差保护保护死区的缺点,对控制回路进行了必要的改进。改进后的控制回路能够有效地消除比相式母差保护的保护死区。深圳市220 kV水贝站的实际应用验证了改进后控制回路的有效性。

Elimination of the protection dead-zone for phase-comparison busbar diffrential protection

The busbar differential protection,which is necessary,is widely used in the transformer substations of which the voltage grade is equal to or upper 220kV.Since the phase-comparison busbar diffrential protection demands to determine which busbar has fault according to the busbar-tie current phase,there exists protection dead-zone as the dual busbars has faults one after the other.Based on the shortcoming,the control loop is improved in this paper.With the reformative control loop,the protection dead area can be eliminated effectively.Also,the improved control loop is validated on the system of the 220 kV Shuibei transformer substation in Shenzhen City.