Bilinear tuned mass damper for spar-type floating wind turbines

Abstract

As the dynamic stability of a spar-type floating wind turbine (SFWT) must be ensured for a secure and robust operation, tuned mass dampers (TMDs) have been proposed to reduce the vibration of the SFWT platform. However, the TMDs in previous studies have several limitations. First, the previously used linear TMDs successfully reduced platform vibration in the absence of wind thrust forces. However, their performance is not satisfactory in the presence of strong winds; if the SFWT structure tilts due to strong winds, the mass of the TMD remains close to the inner wall of the platform. This behavior undermines its vibration reduction performance. To address this issue, a bilinear TMD is introduced in this work. The bilinear TMD significantly reduces vibration even when a strong wind thrust force is applied. Second, previous studies determined the optimized parameters of the TMD based on the free response of the SFWT structure. However, this optimization leads to a low performance TMD when dynamic and stochastic loads were imposed. To address these limitations, this study introduces a bilinear TMD and optimizes its parameters for a variety of operational wind conditions. The bilinear TMD outperforms previous TMDs in every evaluated wind condition by 10%-15%.