A RELIABILITY APPROACH TO TRANSMISSION EXPANSION PLANNING USING MINIMAL CUT THEORY

This paper presents a minimal cut set based approach for the reliabili ty evaluation of an optimally planned transmission system (Part I) and obtains a configuration of transmission lines to achieve a desired fa ilure rate set by the planner (Part II). In Part I an algorithm is dev eloped to find minimal cuts which contain the system components. Overa ll system reliability indices are then calculated by considering that any bus failure causes system failure. In Part II the system failure r ate and other reliability indices are calculated using system first-or der minimal cuts based on the criteria that (a) the system fails if ov erload occurs in a line or the bus voltage variation is greater than /-11% and (b) the system fails if overload in a line and bus voltage v ariation greater than +/-11% occur simultaneously. Part II excludes co mponents in the system and shows how to decrease the failure rate by a dding lines and subsequently to achieve a network configuration for a desired failure rate set by the planner for each of the above criteria . A six-bus transmission network is considered to study the applicatio ns of the algorithm developed.