一起变压器差动保护区外故障动作分析

Analysis of a fault action outside the transformer differential protection zone

某330 kV线路发生单相接地故障后,差动保护动作跳闸,与此同时,1号变压器A套保护差动动作跳闸,B套保护差动启动未动作。经现场检查分析,变压器A套差动保护高压侧电流二次回路中性线在端子箱处开路。针对该事件保护动作原因及过程进行了详细分析,并就防范措施进行了改进,供专业技术人员借鉴与参考。

A single-phase ground fault occurs in a 330kV line,the differential protection trips.The differential protection of a transformer trips at the same time,and the differential protection of B transformer does not act.Through on-site inspection and analysis,the neutral line of secondary current circuit at high voltage side of a set of differential protection of transformer is open at the terminal box.The causes and process of the event protection action are analyzed in detail here,and the preventive measures are summarized for the reference of professional and technical personnel.