Closed-loop testing of an overcurrent relay using a real-time digital simulator

This work presents a detailed overview of the mathematical models and procedures used to conduct closed-loop testing of overcurrent relays using a real-time digital simulator. The example study system presented in the paper is designed to highlight the capabilities of the real-time simulator for closed-loop relay testing without being overly complex. The paper presents results from typical closed-loop performance tests on a SEL 311C relay configured for overcurrent applications.