Methodology to incorporate stuck condition of the circuit breaker in reliability evaluation of electrical distribution networks

The random failure of a circuit breaker (CB) in a power distribution network adversely impacts its ability to maintain supply continuity to its electricity customers. Among different CB failure modes, the failure to open, or the stuck condition, of a normally closed CB causes the operation of its backup breaker(s) leading to outages of multiple healthy feeders. Stuck condition is a low‐probability failure event, but has wide‐spread consequences when it occurs. This study proposes a generalised analytical methodology to identify the failure events due to the stuck breaker condition. The complexity of the reliability evaluation of a modern distribution system involving multiple switching arrangements is achieved through a search algorithm and repeated matrix operations that can readily be implemented in a computer program. The methodology is illustrated using a test distribution network. The usefulness of the methodology is demonstrated by quantifying the impact of the stuck breaker condition on load point and system reliability indices. The developed methodology can be a useful tool for industrial/commercial customers and utilities to incorporate the impact of breaker failures, including stuck breaker conditions, and make wise investment decisions in the upgrade and maintenance of the distribution network components and the protection system.