Optimal setting of directional over‐current relays in distribution networks considering transient stability

Summary Because of the nonlinear characteristic of directional over-current relays (DOCR), optimal setting and coordination of DOCRs are a complicated task in an interconnected distributed network. These relays are usually coordinated without considering constraints of power system transient stability. In this paper, we present a novel methodology for relay coordination considering transient stability as a constraint in optimization problem of over-current relays setting. The relays are set and coordinated based on the obtained results. For this purpose, an appropriate objective function is proposed, and then a two-phase procedure is used in order to consider relays constraints. Pattern search (PS) algorithm is employed to solve the problem under MATLAB software. Results of the proposed approach on a typical distributed network are shown and discussed. These results signify the effectiveness of the presented method. Copyright © 2015 John Wiley & Sons, Ltd.