Pre-processing of the optimal coordination of overcurrent relays

This paper presents a method to reduce the number of constraints and detect those that make the optimization of overcurrent relay settings to be infeasible. By reducing the number of constraints, the feasibility of the optimization is increased and the run-time of the program is decreased. It should be noted that, in the optimal coordination methods, the operating times of the relays are minimized in the frame of the objective function subjects to the so-called coordination constraints. However, a new method for optimum coordination of protective relays based on only constraints has been developed by authors of the paper. The pre-processing reduction constraints method introduced in this paper can be used for any optimal coordination of overcurrent relays. The new method is supported by results obtained from a typical test network and a real power system network. (c) 2005 Elsevier B.V. All rights reserved.