Analysis of an Accident of Incorrect Action of Relay Protection Device Due to Failure of Phase Selection

Abstract

The power system relay protection plays a very important role in the safe operation of the power grid. When the primary equipment of the power grid fails, it can quickly remove the fault and issue an alarm. Combined a case analysis of an accident of incorrect operation of a 220kV line protection device, firstly, the principle of phase selection of line protection is introduced. Then the criteria, advantages and disadvantages of various phase selection components are analyzed. Finally, the improvement method of the criteria for phase selection is discussed in the paper, which is beneficial to avoid the occurrence of similar-accidents and improve the reliability of power grid operation.