Closed-Loop Traveling-Wave Relay Testing (TWRT) using RTDS Real-Time Simulators

This paper presents a methodology to perform closed-loop Traveling Wave Relay Testing (TWRT) for transmission lines in power systems using RTDS real-time simulator. The Traveling-Wave Relays (TWRs) have a high sampling rate, e.g., around 1MHz, therefore, one requirement for TWRT is that the simulator operates at a small time-step, i.e., in the order of one microsecond. The TW-based protection elements operate based on current and voltage TW signals that are derived from the High-Frequency (HF) response induced by faults on the transmission line. This paper shows that employing inaccurate line models in a simulator can result in incorrect TW signals. Therefore, another requirement for TWRT is to use accurate line models. Fulfilling these requirements requires high computational power and introduces challenges to real-time simulators for the TWRT application. This paper presents two real-time simulator approaches for TWRT: (i) an FPGA-based and (ii) a multi-core CPU-based approach. The proposed approaches are employed to test commercially available TWRs and the results are reported.