Protective Relay Coordination for Micro-grid Operation Using Particle Swarm Optimization

With the increasing penetration of Distribution Generation (DG), micro-grid operation becomes an attractive and valuable option. In order for micro-grids to become a viable option, issues such as micro-grid control and protection must be addressed and well established. The paper focuses on micro-grid protection and proposes the use of directional overcurrent relays for protecting a micro-grid consisting of synchronous based DGs. The key issue in selecting the relay settings is to achieve the minimum possible operating times while maintaining coordination among all relays. In this paper, the relay coordination problem is formulated as a Mixed Integer Nonlinear Programming (MINLP) problem and is solved using Particle Swarm Optimization (PSO).