Impact of DC Circuit Breakers on Transient Stresses within Modular Multilevel Converters in Bipolar HVDC Systems

Unlike point-to-point (PtP) HVDC links, multi-terminal HVDC (MTDC) systems require effective protection against DC-side faults to minimize the resulting power outage. DC circuit breakers (DCCBs) and current-limiting reactors are prominent solutions, yet their impact on converter component stresses during transients remains insufficiently quantified. This paper evaluates whether the integration of DCCBs intensifies existing transient stress mechanisms and introduces additional stress conditions for converters, in comparison to state-of-the-art PtP connections. Using electromagnetic transient simulations, a bipolar PtP HVDC system without