600 MW机组发电机励磁系统故障导致机组跳闸原因分析

Analysis of Unit Trip Caused by Excitation System Failure of 660 MW Unit

某火力发电厂600 MW机组运行期间,在启动给水泵时,励磁系统故障触发机组联跳。通过分析,确定原因为汽轮机PC-A段电压降至双电源切换装置失压切换定值,而切换装置因执行机构卡死未能及时切换至MCC-B段,从而导致励磁系统冷却风扇供电中断,励磁系统故障跳闸。后将主路断电后延时切至备路时间及主路低电压定值进行了修改,解决了励磁系统冷却风扇故障的问题,保障了励磁系统的稳定运行。

During the operation of a 600 MW power plant,when the water supply pump is started,the failure of the excitation system triggers the unit jump,resulting in the unsafe equipment of the unit and the economic loss of a large amount of load.During the period,the reasons for switching the dual power supply in the excitation system and the mechanism of switching the dual power supply switch are in the middle position.After determining the reasons,the measures such as switching time of the dual power supply switching device of the excitation system and checking the switching value of the main road loss voltage,adjusting the position of the low-voltage Transformer voltage regulating and separating joint,and improving the remote transmission function of the fan power switching signal of the excitation system are formulated.The problem of cooling fan failure in excitation system is solved,and the stable operation of excitation system is guaranteed,which lays a solid foundation for the stable and continuous operation of the unit.