Vibration suppression performance comparison of floating offshore wind turbines using a tuned liquid column damper and a tuned mass damper

Floating offshore wind turbines (FOWTs) are exposed to the combined effects of wind and waves for a long time, and the additional floating platform motion often leads to excessive vibrations in the tower structure, which in turn affects the safety and reliability of the whole system. Effective vibration suppression of these vibrations has always been a key issue in research. In this study, two of the most commonly used passive structural control devices used to mitigate vibration in FOWTs are considered: tuned mass dampers (TMDs) and tuned liquid column dampers (TLCDs). A comparative evaluation of their vibration mitigation performance applied to the FOWT is carried out. First, to implement the optimal design of parameters for the TMD and TLCD, simplified 3-degree-of-freedom (DOF) mathematical models for the FOWT with the TMD/TLCD are derived and established. The simplified mathematical model is further validated, and the optimal design and parameter study of the TMD and TLCD are investigated using the 5 MW barge FOWT as the benchmark research object. Evaluations and comparisons of the vibration control performance of TMD and TLCD are performed on the basis of fully coupled time domain analysis in OpenFAST, considering the FOWT in operational, nonoperational, and extreme conditions. The results reveal a significant difference in the performance of the TMD and TLCD for tower vibration suppression under various conditions, with more prominent performance under nonoperational and extreme conditions. In addition, the stroke limitation condition of the TMD has a greater influence on performance. The TMD with a large stroke has the most prominent performance, whereas TLCD effectively mitigates tower vibration under different conditions through small liquid column motion.