Evaluation Of Relay Protection Operation State And Hidden Failure Detection

As the most troublesome failure of relay protection,hidden failure is one of the important reasons of cascading failure and disconnection of power systems.Recently,It is significant to find out an effected way to detect hidden failure of protection relays.In this way,we can improve the construction of intelligent substation and the reliability of power system.To solve above problems,this paper presents an improved analytic model to detect hidden failure of protection relays and a hybrid automata model to simulate the state of protections.Then these methods are used to detect abnormal state of protection system and check the adaptability of protection setting and parameters.The details are as follows:1)Based on the principles of protective relay settings and the rules of circuit breaker trips,the hidden failure detection analytic method of logical equations is built using the data collected by Protection Relay Information Management System and Fault Recording System.Then the analytic model is simplified to improve the speed and accuracy of model solving.We also express analytic expression in matrix form for future study on automatic modeling.Then analyzing the uncertainty of transfer signals,protective relay action and circuit breaker tripping,an evaluation index of the solution's possibilities is proposed to help finding the optimal solution.We use discrete particle swarm optimization to solve this model.Finally,the comparison between the real state and expected state is used to detect hidden failures.2)Based on hybrid automata model,a new simulation method of protection system is presented by combining continuous process of primary system and discrete process of secondary system.Taking overcurrent relay and impedance relay as example,this paper presents hybrid automata models of protection schemes by analyzing behavior principles and logical relations of protection relays.In order to detect the hidden failure causing by alarm signals,Stuck Mode is built.Using actual alarm signals,the hidden failure causing by alarm signals can be detected effectively.Examples demonstrate that these methods can be used to check hidden failures of protection relays effectively.