500 kV变压器中压侧及220 kV出线零序过流保护配置及整定方法研究

分析了目前500 kV变压器与500 kV侧出线、220 kV侧出线零序过流保护的整定配合方法，发现500 kV变压器中压侧零序过流保护的整定配合很难，会出现越级动作的可能。在此基础上提出了500 kV变压器的中压侧采用零序反时限保护来代替无方向定时限零序过流保护，同时220 kV侧出线的定时限高阻段保护也采用零序反时限保护的配合方案。实践证明，这种方案解决了保护配合难点，杜绝了线路发生接地故障时而引起的变压器零序过流保护误动，从而保证电网的安全稳定运行。

Research on the configuration and the setting method for the zero sequence overcurrent protection at the middle-pressure side of the 500 kV transformer and in the 220 kV outgoing line

According to analysis on the setting method for zero-sequence overcurrent protection of 500 kV transformer with 500 kV outgoing line and 220 kV outgoing line in this paper,it is found that the configuration and the setting of zero sequence overcurrent protection at the mid-voltage side of the 500 kV transformer is difficult and can cause relay protection skip action.Based on the analysis,this paper puts forward one new project.This project uses inverse-time zero-sequence overcurrent protection instead of no...