A New Optimal Approach for Coordination of Overcurrent Relays in Interconnected Power Systems

A new method for optimum coordination of overcurrent relays is proposed. The proposed method is based on only constraints. Minimization is inherently included by setting the time dials to minimum and increasing their values gradually. Configuration changes of the network is taken into account. The method does not need any initial solution. It can consider both linear and nonlinear relay characteristics models. The optimal settings of overcurrent relays for eight-bus and England Norweb networks are obtained, and comparison between the new method and existing methods is made.