主变不完全差动保护的定值整定和选择性问题

主变差动保护范围包括低压侧母线且母线上接小容量隔离变,隔离变高压侧CT不接入主变差动保护,这种接线构成了不完全差动保护,其定值整定方法与完全差动保护不同,且存在选择性的校核问题。本文提出了定值整定的方法和选择性校核的方法;当选择性不能满足要求时,从速动性、灵敏性、选择性角度提出了四种实用的改进方案,并对各种方案的优缺点进行了比较。

Problems of setting and selectivity for incomplete differential protection of transformer

The range of differential protection of transformer include the bus on low-voltage side,where a low-capacity insulating transformer is installed,though CT on the high-voltage side of insulating transformer is not included in the range of protection.The mode of connection is called incomplete differential protection,which is different from complete differential protection and brings the problems of setting and selectivity.This paper gives a method of setting and checking selectivity,and presents four practical improved schemes from the sides of rapidity,sensitivity and selectivity when selectivity can not meet the challenge.