Bidirectional vibration control for fully-coupled floating offshore wind turbines

Abstract

The vast and stable wind resources present in deep waters have made deep-sea floating wind power the mainstream trend for future development. However, the operating environment of offshore floating wind turbines is complex and variable. The joint action of wind and waves causes significant platform motion and turbine vibration, reducing power generation efficiency, causing structural damage, and shortening the service life of turbines. Hence, this study focuses on the NREL 5 MW DeepCwind semi-submersible wind turbine and establishes a fully-coupled floating wind turbine model utilizing the SIMPACK multi-body dynamics software. The model includes aero-, hydro-, flexible body structure, mooring, control, and transmission chain components. 3D pendulum tuned mass dampers (3D-PTMD) and bilinear tuned mass dampers (2TMDs) are designed to control the bidirectional vibration causes due to wind-wave misalignment in the platform motion and nacelle displacement of the floating wind turbine. The research results show that: For the roll and pitch of the platform, there is only one platform roll or pitch main frequency, and the amplitude at the main frequency can be effectively reduced by setting the frequency of 2TMDs near the main frequency, thereby suppressing the vibration of the platform; For the displacement of the nacelle, in addition to the main frequency of platform roll or pitch, there is also a secondary frequency of first-order bending of the tower, 2TMDs corresponding to the main frequency can effectively reduce the amplitude at the main frequency, and 3D-PTMD corresponding to the secondary frequency can effectively reduce the amplitude at the secondary frequency, it is better to configure 2TMDs alone than 3D-PTMD alone, and it is best to configure both at the same time.