核电站1000 MW级机组的发变组保护配置

Generator & transformer protection configuration for 1000 MW unit of nuclear power station

介绍了1000 MW级核电机组的接线方式和运行特点,提出发变组保护的配置原则:主保护双重化配置,加强主保护及简化后备保护。按主保护及后备保护的分类,主要对差动保护、100%定子接地保护、过激磁保护、失磁保护、转子接地等保护进行配置说明,其中对100%定子接地保护、失磁保护、转子接地保护所采用的保护原理及出口方式进行了详细介绍,例如100%定子接地保护采用外加20 Hz交流信号;失磁保护采用导纳原理的定子回路判据;转子接地保护采用单端注入式原理,定期进行转子对地绝缘检测。此外对核岛系统的联锁保护做了一定说明,例如反应堆冷却剂泵转速低保护需要联跳500 kV超高压开关,使发电机带厂用电运行。对发电机差动保护有重要影响的电流互感器,主要受到空间大小的因素影响而选择P级电流互感器,经计算校验表明选择5P60的电流互感器可满足保护不拒动的要求。

The connection type and operating characteristics of 1000 MW nuclear power station are introduced and the configuration principle of generator transformer protection system is put forward ：the dual-configured main protection should be enhanced and the backup protection simplified.According to the category of main protection and backup protection,their configurations are described,mainly including the differential protection,100 % stator grounding protection,over-excitation protection,loss-excitation protection,rotor grounding protection,etc.The protection principles and tripping actions of stator grounding protection,loss-of-excitation protection and rotor grounding protection are analyzed in detail.The 100 % stator grounding protection is based on external 20 Hz AC signal principle,the loss-of-excitation protection adopts admittance principle,and the rotor grounding protection applies the single terminal injection principle by periodic detection of insulation between rotor and earth.The interlocking protection of nuclei island system is described briefly,for example,the low speed protection of reactor cooling pump needs 500 kV circuit breaker for inter-tripping the unit into house generating operation.The P-series current transformer is selected for generator differential protection due to the space restriction and it is verified by calculation that 5P60 current transformer can satisfy its requirement for no-rejection.