Reliability and availability analysis methodology for power system protection schemes

A new methodology is presented, allowing to evaluate protection systems reliability and availability indexes, taking into account equipment failure and repair rates. The protection scheme is translated into a reliability graph, enabling to identify all possible logical occurrences in the system, either meaning failure or successful operation. Evaluation of the system reliability and availability indexes is achieved by Monte Carlo simulation. The methodology is applied to a typical transmission line protection bay, for different time to repair scenarios, and conclusions on asset management options are drawn.