Abstract

High-Voltage DC Circuit Breakers (DCCBs) represent a key enabling technology for the development and reliable operation of multi-terminal DC networks. In this context, the Network DC project investigates the operation of DCCBs to advance the technology readiness level, facilitating the development of HVDC networks in Great Britain. This paper studies the effects of internal faults in hybrid DCCBs, which appear as a leading technology with installed units operating at 535 kV and breaking current capabilities of 25 kA. The analysis considers a load commutation switch topology consisting of four main components: Mechanical Switch, Auxiliary Commutation Circuit, Modularised Solid-State Switch and Energy Absorption Devices. The modularised solid-state switch consists of hundreds of bidirectional Sub-Modules (SMs) which conduct the fault current until the mechanical switch contacts reach a sufficient distance before the insertion of the energy absorption arresters. Thus, the presence of internal failures in the solid-state switch leads to extended opening times for the DCCB, increased energy levels in the absorption devices and even the impossibility of performing the fault current breaking.

Sebastian Neira, Seyed Saeid Heidari Yadzi , Stephen Finney , Paul Judge , Colin Foote , Suresh Rangasamy , Asif Khan , Ben Marshall , Alberto Bertinato , Hind Bekkouri 

Presented at IET ACDC 2025