厂用电6kV母差保护退出运行可行性分析

Feasibility Analysis of Withdrawing Operation of 6 kV Bus Differential Protection in Factory

母线差动保护,取母线电流互感器两端进出电流矢量和作为判据。正常运行时,母线进出的电流大小相等,相位相同。当母线发生故障时,电流不再保持平衡,当其测量值大于保护设定值时,保护动作,跳开母线上所有断路器。保护一般不使用在厂用电6kV段,而广东粤电珠海发电厂6kV段配备了母差保护。其搭配的电磁式母差继电器容易误动作,导致母线失电,机组降负荷。为防范保护误动作事故再次发生,文章讨论了广东粤电珠海发电厂6kV保护整改方案,通过全厂保护整定计算取代母差保护。

The busbar differential protection takes the vector sum of the currents at both ends of the bus current transformer as a criterion.In normal operation,the current flowing in and out of the busbar is the same and the phase is the same.When the busbar fails,the current no longer remains balanced.When the measured value is greater than the protection setpoint,the protection action is taken and all circuit breakers on the busbar are tripped.The protection generally does not use the 6 kV section in the plant,but the 6 kV section in our factory is equipped with busbar protection.Its collocated electromagnetic relays are prone to misoperation,resulting in loss of power to the buses and load shedding.In order to prevent the re-occurrence of protection malfunctions,this article discusses our 6 kV protection rectification program and replaces the busbar protection through the whole plant protection setting calculation.