Hardware-in-the-loop testing of protection relays in distribution feeders with high penetration of DGs

To study or control the behavior of an actual equipment, such as a protection relay in a complex power system, real-time digital simulators can be employed in order to provide a safe and efficient environment for researchers. The goal of this paper is to investigate and verify the operation of an “actual” overcurrent protection relay in a simulated distribution system. More precisely, this work has investigated the behavior of instantaneous overcurrent protection element of the SEL-351S™ relay using OPAL-RT digital simulator through hardware-in-the-loop testing to demonstrate desensitization of the relay in protecting a distribution feeder when various levels of distributed generations exist in the system.