Prediction of Circuit Breaker Time-to-Failure Considering Generation Capacity Growth

This paper describes a method for predicting circuit breaker time-to-failures using a probabilistic operational model that incorporates generation capacity growth. Increases in generation capacity may cause fault current levels to approach or exceed circuit breaker ratings. This condition may increase the probability of a circuit breaker failure. Circuit breaker failures result in common-mode multiple outages that seriously affect system reliability. Therefore, it is important to be able to predict the expected life of a circuit breaker from the expected operations and levels of electric currents to be interrupted. The analysis outlined in this paper highlights changes in circuit breaker reliability related to generation growth. Maintenance and replacement can be improved from the proposed analysis while maintaining high reliability levels for power systems. The proposed comprehensive model for predicting the time-to-failure of circuit breakers consists of the following: (a) a detailed reliability (Markov) model of the various components of the breaker, (b) a breaker-oriented, three-phase power system model linked with a probability model of fault events - this model provides the probability distribution of fault currents to be interrupted by specific breakers and (c) a probabilistic model of future generating capacity increases based on expansion plans of the power system. The method is demonstrated on a modified breaker-oriented three-phase IEEE 24-substation system.