Hardware-in-the-loop Relay Testing in Dominion's Blackstart Plan

When a complete or partial blackout has occurred, the system operator is responsible for assessing the system condition, restoring the system based on the emergency operation procedures and re-establishing the integrity of the interconnection. This procedure is called blackstart. During the blackstart process, the system is operating in relatively weak condition, since the generation capacity is small in each blackstart path and there are plenty of different blackstart transients, such as transmission line energization, load pickup, generator synchronization, and island synchronization. All these blackstart transients and possible small fault current may cause the relay protection function to misoperate. In order to validate the relay performance in the Dominions blackstart plan, Real-Time Digital Simulator (RTDS), amplifier, and SEL relay are utilized to perform the hardware-in the-loop real-time relay testing. The QUAD distance protection function and time-inverse overcurrent protection function are tested for both blackstart steady state operation and blackstart switching operation. The possible problems for the relay protection functions during the blackstart process are found from the testing results.