Fault Diagnosis Method of Power Grid Considering Reliability Assessment of Relay Protection Devices

The expansion of modern power grid scale and the enhancement of interconnection make the fault diagnosis of power system face more complex data environment, which improves the difficulty in guaranteeing the operation safety and stability of power grid. In order to solve the problem that power grid fault diagnosis method is not easy to get accurate results when complex fault with no obvious failure characteristics occurs, a fault diagnosis method of power grid considering reliability assessment of relay protection devices is proposed. Based on the alarm information which has weak correlation with failure, the Markov model of protection reliability is established, and the state space method is used to obtain the probability of refuse-to-operate failure and mis-operation failure. The results of protection reliability assessment are added to the objective function of the fault diagnosis method based on the analytical model. Variable length chromosome genetic algorithm is used to solve optimal fault hypothesis. The feasibility of the method is verified by the actual complex fault case.