Study on hidden failure of relay protection in power system

Studies of major blackouts reveal that power system protection devices have contributed to a majority of system disturbances. As the most troublesome failure of relay protection, hidden failure needs more attention. In this paper, emphasis is placed on the importance of studies on hidden failure of relay protection which causes cascading failures. By clarifying the concept, characteristics and harmfulness of hidden failure, the paper proposes two response measures -vulnerability analysis and risk assessment, monitoring and control system, and draws a conclusion that the corporation of both could be the developing trend in the future.