Performance Study and Specification Framework for DC Circuit Breakers in Multi-Terminal HVDC Networks

Breakers (DCCBs) in a 12-terminal ±525 kV HVDC bipole network under various operating conditions and fault disturbances. The use case represents a complex and ambitious DC grid configuration envisioned for Great Britain, integrating transmission reinforcement, offshore wind, and international interconnection. The study investigates the feasibility of DCCB deployment in a multi-terminal and vendor neutral environment with a coordinated control and protection philosophy. Four scenarios are analysed, each representing different pre-fault power flow conditions. The results demonstrate that DCCBs can operate within acceptable limits of current interruption, energy absorption, and transient interruption voltage (TIV), even under conservative protection assumptions. The DC grid consistently recovered to a new steady-state post-fault, although converter overload and high arm currents are observed in some cases. These findings highlight key constraints and design considerations for future DC grid development and DCCB specification which promotes interoperability and flexibility in future HVDC network developments.