大型发电机零序过电压定子接地保护的改进

现行零序过电压定子接地保护死区大，动作延时长，难以满足大型发电机组灵敏、快速跳闸的要求。根据定子接地时零序电压与接地电流成正比关系，提出反时限零序过电压定子接地保护并给出了整定原则，提高了定子区内严重故障时保护动作的速度。引入高压侧零序电压闭锁判据，降低了零序电压的动作整定值，一定程度上减小了保护的动作死区。

Improvement on Stator Ground Protection Based on Zero-sequence Overvoltage for Large Generator

The traditional stator ground protection based on zero-sequence overvoltage has the disadvantages of large dead zone and long time to delay, which is difficult to meet the requirements of sensitive and fast trip for the large generator. As the zero-sequence voltage is proportional to the ground fault current, the inverse-time zero-sequence overvoltage ground fault protection for stator is presented and the setting principle is given. It improves the speed of protection against serious fault in the stator. By using the block criterion of zero-sequence voltage on high-voltage side, the setting value of zerosequence voltage is decreased, which diminishes the dead zone of protection to some extent.