Coordinative performance of HVDC circuit breakers in MTDC grids

The objective of this paper is to investigate the coordinative performance of different types of high voltage DC (HVDC) circuit breakers (CBs) in multi-terminal DC (MTDC) grids. Several different HVDC CB technologies are emerging as a solution for the protection of offshore MTDC grids. There is a need for coordinative operation between different types of DC CBs in the same network. In this paper, two typical types of DC CBs are modelled in detail and implemented in a 4-terminal MTDC grid in PSCAD environment, by considering operation time, interruption capability and interruption characteristics. Since the requirement of the DC CBs depends on the magnitude of the interrupted current where they are implemented, the fault scenarios in all terminals are studied and the worst scenarios are selected to demonstrate the coordinative performance of different DC CBs. Four cases are defined and demonstrated by two different types of CBs at each terminal of the cable. DC CBs perform differently with the change of the operating time and the locations where they are implemented. The performances and energy absorption are compared and analyzed. The obtained results can be used as DC CB's selection optimization methodology for future MTDC grids.