Design and Techno-Economic Evaluation for Large-Scale Offshore Wind Power Transmission Scheme

As offshore wind farms continue to scale up in both distance and capacity, the design of transmission systems has become a critical factor in the effective development and utilization of offshore wind energy. In response to the growing trend of larger wind turbine volume and the densification of offshore platforms, this paper presents a design methodology for compact transmission system tailored to large-scale offshore wind farms, with a focus on the collection system and reactive power control. Firstly, the feasibility of 66 kV single-stage collection system and a unified reactive power compensation scheme using wind turbines and Modular Multilevel Converter (MMC) is analyzed. On this basis, a compact transmission scheme based on MMC-HVDC is proposed for large-scale wind farms. Secondly, a cooperative reactive power control strategy is introduced, leveraging the reactive power regulation capabilities of both wind turbines and MMC. This approach enhances the system’s reactive power and voltage regulation capabilities, as well as its low-voltage ride-through (LVRT) performance. Finally, the effectiveness of the proposed transmission scheme and reactive power control strategy is validated through simulations, and a techno-economic comparison is made with conventional transmission systems.