Metocean-Dependent Blade-Pitch Control of Floating Wind Turbines: Balancing Regulation and Pitch Activity

Floating offshore wind turbines operate under continuously varying atmospheric and ocean conditions, whose influence is not explicitly accounted for in conventional blade-pitch controller scheduling. As a result, control strategies designed to provide strong rotor-speed regulation may introduce unnecessary blade-pitch activity under certain environmental conditions. This work proposes a metocean-dependent control methodology that adapts the regulation authority to the prevailing wind and wave excitation, balancing power regulation and actuator demand. A family of controllers with different regulation capabilities is developed, and a reduced-order control-oriented model is used to map turbulent wind and wave disturbances into the closed-loop response, enabling the selection of the most suitable controller for each metocean condition. The floating-feedback filter bandwidth is also adapted to limit wave-induced control activity. The methodology is evaluated through nonlinear OpenFAST simulations under five representative metocean conditions at a mean wind speed of 12 m/s. Compared with an advanced baseline controller, the proposed strategy reduces collective blade-pitch activity by approximately 52–64%, while maintaining comparable power regulation. Platform-pitch fluctuations are reduced across all investigated conditions, together with reductions in tower-base fore–aft damage-equivalent loads of approximately 2–18%. The results demonstrate that maximizing regulation authority is not always the most effective control strategy, and that metocean-dependent controller selection can substantially reduce actuator demand while preserving regulation performance and improving the structural response.