Capacitor-based Medium Voltage Test System for DC Circuit Breakers

This paper studies the design of a capacitor-based 12 kV test circuit for evaluating the performance of DC Circuit Breakers (DCCB) in Medium Voltage DC (MVDC) applications. The proposed circuit offers a cost-effective solution for realistic testing in research laboratories. It also accommodates current reversal during interruption, as required with latest DCCB technologies. The paper details the key test circuit requirements, component selection process, and a comprehensive PSCAD simulation model. The simulation model analyzes the operation of both the test circuit and DCCB under various test conditions, including charging circuit performance, discharge circuit response with the DCCB closed, and fault current interruption with different current thresholds. The results demonstrate that the MV DCCB test circuit achieves the desired peak current, it’s derivative, and energy, while post-fault voltage stress is lower than in real circuits.