Per-Phase and 3-Phase Optimal Coordination of Directional Overcurrent Relays Using Genetic Algorithm

Penetration of the power grid by renewable energy sources, distributed storage, and generators is becoming increasingly common. Increased utilization these resources (DERs) has given rise to additional protection coordination concerns, particularly where they are utilized in an unbalanced manner or loading among phases unbalanced. Digital relays such as SEL-751 (produced Schweitzer Engineering Laboratories, Pullman, WA, USA) series have capability being set on a per-phase basis. This underutilized common practice. Additionally, optimization algorithms for determining relay settings, time-overcurrent characteristics (TOCs) generally not treated variables assigned before running algorithm. In this paper, TOC options themselves discrete be considered A mixed integer nonlinear programming problem (MINLP) up goal minimize operating times. genetic algorithm (GA) approach implemented MATLAB two cases considered. first case, Time dial setting (TDS) each three-phase second settings Relay TDSs TOCs both simultaneous control variables. Despite stochastic nature using systems found allow shorter However, relatively balanced systems, it best use if computation time importance.