Short Term Reliability Analysis for Protection System with Average Unavailability

In the short-term reliability evaluation, the state probability and unavailability are time-dependent. Remarkable error will be introduced by using the steady-state unavailability in probabilistic simulation. In this paper the analytical solution to the instantaneous state probability is derived, and the average unavailability during the evaluation period is proposed. An estimation to the average unavailability is quantified considering the time elapse from the latest transition. The proposed algorithm is validated by a short-term reliability evaluation to the protection system, and influences of the initial state, the evaluation period, the transition rate, the latest transition are studied.