Addressing Overcurrent Relay Miscoordination Caused by Network Topology Changes During Fault Isolation

Protection coordination is a critical aspect of reliable and safe power system operation. As the traditional radial distribution system undergoes a transformation into a more complex mesh system and network of microgrids, it becomes crucial to establish efficient coordination among protection devices. This coordination aims to minimize the impact of faults, uphold power system reliability, and safeguard both equipment and personnel. This paper addresses the integrity of protection coordination; it aims to investigate the issue of miscoordination in overcurrent relays, that can occur in mesh networks with Distributed Generators (DG). Traditionally, protection coordination challenges are addressed under the assumption of a static network. However, during fault isolation, there are often transient changes in the network topology that can affect the coordination of overcurrent protection relays. This study identifies and presents the issue of miscoordination in such scenarios, and proposes a nonlinear optimization formulation to effectively prevent this possible miscoordination.