一起蓄能机组核相过程电压异常分析

Analysis on an Abnormal Voltage Fault During Phase-checking Process of Pumped Storage Unit

通过对一起蓄能机组核相过程引起的电压异常现象进行分析,确认引起该电压异常的原因是电磁式电压互感器与发电机出口断路器对地电容激发的分次谐波谐振引起的电压位移。利用仿真试验验证了该核相过程极易发生谐振故障,同时总结了不同谐振时电压位移的特点。针对目前蓄能电站采用系统电源完成核相工作的实际情况,提出在条件允许的情况下取消发电机出口断路器对地并联电容、选取伏安特性好的电压互感器、保证断路器三相合闸的同期性是防止谐振造成电压异常的预控措施;提出现场处置可采取临时改变参数方式避免谐振现象,所提出的措施和方案可以有效减少核相过程中发生电压异常现象的几率,为新建抽水蓄能电站提供一些经验。

An abnormal voltage fault during phase-checking process of pumped storage unit is analyzed. It is confirmed that the abnormal voltage is caused by the voltage displacement due to the sub-harmonic resonance excited by the electromagnetic potential transformer and the ground capacitance of generator circuit break. Simulation test indicates that resonance fault happens easily in the process of phase checking. The features of voltage displacement for various resonances are summarized. For the actual situation that the existing pumped storage power stations use power supply of grid system for phase checking, suggestions are offered to prevent the resonance from causing abnormal voltage, i.e. in possible condition removing the parallel ground capacitance of generator circuit breaker, selecting the potential transformer with high volt-ampere characteristics, ensuring three-phase closing synchronization of circuit breaker, and temporarily changing parameters for field handling. These suggestions may reduce the happening possibility of abnormal voltage effectively.