The composite fuzzy reliability index of power systems

This paper describes a method for fuzzy calculation of power system reliability. It introduces a composite fuzzy security and fuzzy adequacy indices encompassing the power system segments of generation, transmission, and the segment of load nodes. The fuzzy security index is determined by the security membership grades of the power system components which are found to be the worst in their segments. The fuzzy adequacy index is based on the adequacy indices of generation, transmission, and transmission integration segments. The composite fuzzy reliability index enables the system operator to have a continuous insight into the distance between the power system's actual state and the closest unreliable state by tracking the system's components with the lowest security and adequacy membership grades of the respective segments. The algorithm has been tested on the models of the IEEE Three Area RTS-96 and Bosnia–Herzegovina power systems.