The number of constraints in coordination of distance and directional overcurrent relays (D&DOCRs) in power systems increases significantly by considering changes in network topology, especially in large power systems. By increasing the number of coordination constraints, the complexity of the D&DOCRs coordination problem is increased. Therefore, in this paper, a new method is proposed to reduce the number of coordination constraints in the D&DOCRs coordination problem. In the proposed method, redundant constraints are identified before solving the coordination problem. The proposed method is independent from D&DOCRs settings and operating characteristics of directional overcurrent relays. In order to evaluate the proposed method, two different test systems, namely an 8-bus and the IEEE 14-bus test systems, are used. Based on the presented results, it can be seen that the proposed method is efficient, and by utilizing it, many redundant coordination constraints are identified and removed, helping to obtain effective solutions for the optimal settings with less computational effort.

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