变压器差动保护误动原因综合分析及防误动措施

Synthetic analysis on the causes of mal-operation and preventive measures of transformer differential protection

简要分析了在区外故障过程中、区外故障切除后电压恢复过程中,因CT饱和、和应涌流的注入,导致比率制动和涌流闭锁措施均失败而造成变差误动的典型事例;并列举因二次回路故障、定值设置错误等人为因素造成的变差误动事例,揭示误动机理;指出应从CT选择、变电站运行方式适当改变,差动保护软件抗饱和设计,现场继电保护从业人员责任心和技术水平的提高,现场安全措施及危险点分析予控等方面防止变差保护误动作的措施。

This paper takes a brief analysis on the typical cases of mal-operation of transformer differential proteciton due to CT saturation, the injection of sympathetic inrush and so on,which result in the invalidation of ratio restraint and secondary harmonic inrush blocking measures, during the course of external fault and recovery from the clearance of external fault.Other causes,for example, the occurence of secondary circuit fault and wrong setting on operation values, are also presented in this paper. It is pointed that following measures should be taken to avoid the mal-operations, such as selection of CT, regulation of substation operation ways, design of differential protection immune to saturation, improving the sense of responsibility and the level of theory and technique of workers,enhancing security measures, predicting and controlling of dangerous points and so on. This project is supported by National Natural Science Foundation of China（No.50607006）.