一种适用于核电厂的转子接地保护举刷装置

Discussion on the False Alarm of Rotor Grounding Protection

方家山核电工程的发电机组采用的是旋转无刷励磁系统,其转子接地保护为注入式原理构成。转子接地保护能够在发电机转子出现接地故障后发出报警,故障严重时可作用于跳机,从而保护发电机转子免受故障引起的破坏,对机组的安全有着重要作用。在发电机运行期间曾多次发生转子接地保护报警,根据现场检查分析后得出的结论为这几起报警均属于误报,其产生原因为原厂举刷装置在使用一段时间后会发生卡涩现象,举刷装置卡涩故障的存在会导致系统监测到转子接地电阻值不准确,汽轮机转子接地保护处于失效状态。针对这一情况,本文设计了一套适用于M310机组的转子接地保护举刷装置,同时本论文结合方家山发电机组转子接地保护的配置及其调试、运行、维修的经验,介绍了该举刷装置的原理、设计保护的构成原理,并分析了误报警形成的几个主要原因,针对这些原因给出了有效的方法,避免了举刷装置的卡涩,发挥其应有的作用。

The generator unit of Fangjiashan Nuclear Power Project adopts a rotating brushless excitation system,and its rotor grounding protection is composed of injection principle.The rotor grounding protection can issue an alarm after the generator rotor has a grounding fault,and can act on the tripping machine when the fault is serious,thus protecting the generator rotor from the damage caused by the fault,which has an important role in the safety of the unit.During the operation of the generator,there were several alarms of rotor grounding protection.According to the analysis of the field inspection,the conclusion was that these alarms were all false alarms.The reason for the false alarms was that the brush lifting device of the original factory would become stuck after using for a period of time.The existence of the brush lifting device sticking fault would cause the system to monitor inaccurate rotor grounding resistance value,and the turbine rotor grounding protection was in a failure state.In view of this situation,this paper designs a set of brush lifting device for rotor grounding protection suitable for M310 unit.At the same time,this paper combines the configuration,debugging,operation and maintenance experience of Fangjiashan generator unit rotor grounding protection,introduces the principle and composition principle of the brush lifting device design protection,and analyzes several main reasons for the formation of false alarms.In view of these reasons,effective methods are given to avoid the sticking of the brush lifting device and play its due role.