Analysis of Relay Protection Action of an Accident in Power Grid

On the 110 kV outgoing feeder of 220 kV substation,there occurred a series of relay act trip caused by tree fault,which created 110 kV bus loss-of-voltage in the substation.As for the protection action of the accident was analyzed,and the rectification suggestions about the management of setting ralue and the maintenance of circuit breaker mechanism against the external fault maloperation trip of the protection were proposed.