Optimized adaptive protection coordination of microgrids by dual-setting directional overcurrent relays considering different topologies based on limited independent relays’ setting groups

Abstract

• Optimal adaptive protection, considering the limits on the number of setting groups. • Using the DS-DOCRs incorporating independent changes in the setting groups. • Optimal relay curve types and breakpoints for the DS-DOCRs. • Fast protection without selectivity constraint violations in various configurations. • Around 41.66% improvement compared to available studies. Several studies, such as adaptive protection schemes, have been done in the area of smart grids’ protection. However, there is a research gap in developing an adaptive scheme with dual-setting (DS) directional overcurrent relays (DOCRs), considering the limitations of the number of setting groups of protective relays. This research aims to fill such a research gap. Optimizing the relay curve types of the first and second parts of the DS relay models and breakpoints (BPs) improves the speed of the protection scheme based on independent changes in the setting groups of DOCRs. Also, there is no coordination constraint violation in various configurations by applying the proposed method, while it requires only a limited number of setting groups. Therefore, the proposed method can be practical in actual systems because the suggested solutions and protective settings can be easily implemented using commercial relays. The proposed adaptive protection scheme is applied to two test systems (the distribution networks of the IEEE 14-bus and IEEE 30-bus test systems). The comparative test results infer that significant improvement in the speed of the protection system of smart grids can be achieved compared to available studies by the proposed method.