Microprocessor relay evaluations using digital model power system

This paper discusses the simultaneous evaluation of various digital line protection relays using a closed-loop real-time power system digital simulator. This simulator and test was setup to evaluate microprocessor based relay performance and to determine the best suited protection scheme for an upcoming project. This project was complicated with an existing series capacitor bank installed on one end of the transmission line. A digital fault recorder was used for contact output timing for each fault condition. Relay settings were verified and validated through this testing and simulation process. Lessons learned are shared in the paper.