DC grid management of a multi-terminal HVDC transmission system for large offshore wind farms

Abstract

Multi-terminal HVDC transmission system technology using voltage source converters is proposed for integrating large offshore wind farms. Various DC grid management strategies based on coordinated close-loop DC voltage control and DC droop characteristics are proposed, to ensure smooth system operation and proper power sharing among various onshore AC networks. PSCAD/EMTDC simulations for a four-terminal DC system for connecting two offshore wind farms to two different onshore AC networks are presented to demonstrate the robust performance of the proposed DC management modes during wind speed and power variations, and large disturbances caused by the trip of one of the wind farms.