Control strategy for VSC-MTDC grid connection of offshore wind farms with high penetration of renewable energy integration

To address the challenges of limited DC voltage dynamic performance and dynamic power deviations in grid connection of offshore wind farms via multi-terminal VSC-MTDC systems under high-penetration renewable energy integration scenarios, this paper proposes an abnormal-condition-aware master-slave coordinated hierarchical control strategy to enhance system reliability and stability. First, a coordinated control method for the primary and auxiliary converter stations is developed by integrating voltage margin and voltage droop control schemes, based on the dynamic characteristics of converter stations. Second, a dynamic hierarchical control approach is proposed, incorporating DC power fluctuation and converter station regulation capability, which can maintain the balanced active power distribution under abnormal disturbances. Third, a dynamic participation strategy and parameter tuning methodology for converter stations are established to achieve adaptive adjustment of the number of operational converter under various operating conditions, effectively suppressing the dynamic power fluctuations of converter stations and enhancing the DC voltage dynamic regulation characteristics. Finally, the effectiveness of the proposed control strategy under abnormal operating conditions is validated through a five-terminal offshore wind VSC-MTDC simulation system built on the PSCAD/EMTDC platform.