热电厂化学水供电系统保护问题分析

淄博热电厂3号、4号机组化学水供电系统自2002年投产以来,一直存在MCC柜电源断路器不明原因跳闸以及6 kV变压器越级跳闸的问题。同时存在400 V电动机接地故障时PC段出线断路器越级跳闸、出线相邻断路器误动跳闸,以及MCC柜空气断路器拒绝动作、接触器被烧毁的故障。经检查分析确定PC段零序保护定值问题导致MCC柜的电源断路器越级跳闸,MCC柜电动机保护的逻辑错误导致电源断路器越级跳闸,零序TA接线问题导致电动机出现故障时MCC电源的相邻断路器跳闸,提出解决措施,实施后问题得到解决。

Analysis on the Protection Problem of Thermal Power Plant Chemical Water Supply System

Since 2002,after Zibo power plant unit 3 and unit 4 water supply system putting into operation,unexplained tripping of a MCC power circuit breaker and 6kV transformer over-grade trip has long been a problem;At the same time,there are the circuit breaker of PC outlet over-grade trip after the presence of 400 V motor grounding fault;adjacent circuit breaker error trip,as well as the MCC cabinet air circuit breaker refusing action,fault of contact burned.Problems above are checked as follows：first,the zero sequence protection value problem of PC section causes power supply circuit breaker over-grade trip of MCC cabinet;second,logic error of MCC motor protection circuit leads to MCC power breaker over-grade trip;third,zero sequence TA wiring problems lead to adjacent breaker trip of MCC power after motor fault.By taking proper measures problems above are solved.