Optimal Protection Coordination for Mitigating Sympathetic Tripping in DER-Integrated Power Systems

The integration of distributed energy resources (DERs) is revolutionizing the power grid but introduces nu-merous challenges for traditional protection schemes. These include blinding, selectivity issues, sensitivity reductions, and miscoordination. Among these, sympathetic tripping, whereby relays respond to faults in adjacent zones despite no fault in their own zone, has emerged as a critical issue, compromising grid reliability and causing avoidable outages. This paper focuses on addressing sympathetic tripping in DER-integrated networks. A novel mathematical optimization model is developed with pertinent binary and slack variables to respectively model sympathetic trip conditions and differences between relay operation times. The optimization model produces relay settings that coordinate primary-backup relay pairs and mitigate sympathetic tripping instances. Validated on the IEEE 123-bus distribution system, the approach demonstrates reduction in sympathetic tripping, improving protection coordination in DER-rich environments.