Control strategy for HVDC interconnected DC-based offshore wind farm

This paper presents a new control strategy for DC-based offshore wind farm connected to onshore AC grid through high-voltage DC (HVDC) system. The offshore wind farm is composed of variable speed wind turbines driving permanent magnet synchronous generators. Each PMSG is connected to the DC bus through a generator side converter unit. The DC voltage of the DC-bus is stepped up using a full-bridge DC-DC converter at the offshore HVDC station. The onshore HVDC station converts the DC voltage to the suitable AC grid voltage. Detailed modeling and control strategy of the overall system are presented. Real wind speed date is used in the simulation study to obtain realistic response. The effectiveness of the control strategy is verified by simulation analyses using laboratory standard power system software package, PSCAD/EMTDC.