A high-performance hybrid algorithm to solve the optimal coordination of overcurrent relays in radial distribution networks considering several curve shapes

The coordination of overcurrent relays (OCRs) is essential for improving reliability and security indicators in electrical networks. This paper proposes a high-performance hybrid algorithm (HPHA) to solve the optimal coordination of OCRs in radial distribution networks (RDNs). The optimal coordination problem is formulated as a mixed-integer nonlinear problem (MINLP). We considering as decision variables: (1) the pickup current (Ip); (2) time dial setting (TDS); (3) relay type; (4) curve type. The HPHA is composed of a specialized genetic algorithm (SGA) and an efficient heuristic algorithm (EHA). Thus, the HPHA finds the optimum combination of Ip, TDS, relay types and curve types that minimize the relays operational times, ensuring the selectivity for several fault levels. The proposed algorithm considers discrete values of Ip and TDS. The simulation results showed that the proposed technique is efficient, fast, reliable and improves the coordination by decreasing the operational times of OCRs.