First real-time implementation of DC grid protection strategy

This paper demonstrates the performance of a three-terminal DC grid test system modelled in a real-time digital simulator (RTDS) platform at ABB's DC Grid Simulation Center. In this hardware-in-the-loop simulation arrangement, all the converter stations, AC network equivalents, transformers, cables and the DC switchyards including DC breakers are modelled inside RTDS following a dual time-step strategy. However, the entire control and protection system is implemented in the ABB's MACH control and protection platform. The MACH system receives the measurement signals from the RTDS through analog and digital I/O cards and sends switching order to the converter valves and breakers. The selective and time-critical performance of the protection functions in case of DC faults is demonstrated in this paper through real-time simulation.