A Configuration of Multi-Circuit HVDC Transmission System for Offshore Wind Power Plants and its Protection Scheme for DC Line Faults

Abstract

This paper proposes a configuration of multi-circuit HVDC system and its protection scheme for DC line faults for improving reliability. The system consists of multiple DC lines connected in parallel to a DC bus through diodes. These diodes can instantaneously disconnect a faulted line, with the result that no fault current flow from the other non-faulted lines. It can immediately clear the DC fault current by shorting the submodules of the modular multilevel converter (MMC) in the supply side. Simulation results confirm the validity of the proposed protection scheme under a pole-to-ground fault (DC1LG) and a pole-to-pole fault (DC2LG).