Parameter optimization and performance evaluation of a nonlinear energy sink for vibration reduction in TLP floating wind turbine

With the continuous upscaling of offshore wind turbines, vibration problems of floating wind turbines (FWTs) operating under complex sea states have become increasingly critical, while their multimode vibration characteristics pose significant challenges to passive dampers like Tuned Mass Damper (TMD) that are effective only at a single resonant frequency. To address this limitation, this paper proposes using a Nonlinear Energy Sink (NES) to reduce multimode vibrations of a Tension Leg Platform FWT (TLP-FWT). A dynamic model of the TLP-FWT-NES system is first established, and the model parameters are calibrated using the Leven–Marquardt algorithm. The NES parameters are then optimized via Bayesian optimization method under wind-wave loading condition, and its vibration reduction mechanism and performance are compared with those of a TMD. Fully coupled numerical simulations are conducted under various sea states to evaluate the NES's performance. The results demonstrate that the optimized NES can efficiently capture and dissipate the platform pitch and tower vibration energy. The NES exhibits a broader vibration reduction bandwidth owing to its resonance capture cascade and subharmonic internal resonance. The nacelle-mounted NES provides superior vibration reduction and broader adaptability compared to a TMD, offering insights for enhancing the safety and reliability of FWTs.