Control of a Semi-submersible Offshore Wind Turbine with a Tuned Liquid Column Damper

This paper proposes a new type of Tuned Liquid Column Damper (TLCD) for vibration suppression of a semi-submersible offshore wind turbine. The proposed mechanism consists of three columns of liquid equipped with three valves that allow the liquid to transfer between columns. The nonlinear dynamic model of the offshore wind turbine and the TLCD is derived and validated. The model is linearized around equilibrium point and a mixed H - Velocity Based Ground-hook (VBG) controller is designed to suppress vibrations of the platform and achieve the rated rotor speed. The performance of the controllers is investigated through numerical simulations.