A New Thyristor-Based DC Circuit Breaker With an Auxiliary Forced Commutation Branch

The rapid growth of renewable energy harvesting and the integration of renewable energy systems into power systems have significantly increased electricity market attention towards utilizing Direct Current (DC) power systems. The protection of DC systems is still recognized as a challenge to their widespread deployment. Fast DC Circuit Breakers (CBs) are critical components required to ensure the safe and reliable operation of DC systems. Compared to Insulated-Gate Bipolar Transistor (IGBT)-based solid-state DC CBs presented so far, thyristor-based CBs benefit from reduced conduction losses and lower development costs. Nevertheless, this technology has drawn less attraction due to the difficulty in the main DC CB valve commutation in the event of a DC fault. This paper presents a new topology for a unidirectional thyristor-based DC CB for low- and medium-voltage DC systems, addressing the above-mentioned challenges by incorporating a series capacitor block. Compared to the existing topologies presented in the literature, the proposed topology offers several key advantages, including fast operation response, high reliability, reduced main and auxiliary DC CB valves voltage stress, and reduced manufacturing cost. Detailed principle of operation is presented, and simulation results are provided using DC CB modeling in PSCAD/EMTDC software. In addition, a prototype 310 V DC CB with a nominal current of 3.1 A is designed, built, and tested as a scaled-down experimental testbed to verify the effectiveness of the proposed topology.