Evaluation of substation reliability indices and outage cost based on fuzzy arithmetic

Substations and switching stations are critical segments in an electric power system. Their impacts on system operation and the consequential effects of their components failure are usually more dominant in overall power system reliability. There is always a degree of uncertainty in the practical input data used in reliability analysis. This paper presents a conceptual possibilistic approach using fuzzy set theory to manage the uncertainties in the reliability input data such as failure rate, repair time and operation of protective devices. Suitable fuzzy numbers are proposed for components reliability data. Load of feeders are also represented by fuzzy numbers and their impact on ENS (Energy Not Supplied) and OC (Outage Cost) are examined. The proposed approach is applied to a practical 230/63 KV substation and the results are presented.