Virtual inertia coordinated control strategy for offshore wind farm integration via MMC-HVDC

To address the issues of reduced system inertia and frequency decoupling between the wind farm and grid caused by offshore wind farms connecting to the grid via flexible DC systems, a frequency support strategy coordinating offshore wind farms with flexible DC systems is proposed. The inertia and damping characteristics of synchronous machines are simulated in both the flexible DC system and wind farm control strategies, enabling the offshore wind-flexible DC system to participate in system frequency support and improve system frequency dynamic characteristics. Additionally, considering that conventional virtual inertia control may cause secondary frequency drops and accounting for the operational status of individual units, an adaptive virtual inertia control coefficient and a smooth rotor recovery control strategy are introduced. Finally, a model of the offshore wind farm-flexible DC system is established in PSCAD/EMDTC software to validate the effectiveness of the proposed frequency support strategy.