Vibration suppression in floating offshore wind turbines after blade pitch control system failure using tuned mass damper

Existing research in wind turbines mainly focuses on dynamic load mitigation from wind and waves; however, studies on vibration suppression during blade pitch control system failures are limited. This study explores the use of a Tuned Mass Damper (TMD) placed in the nacelle of a Floating Offshore Wind Turbine (FOWT) to reduce turbine and platform vibrations following the blade pitch control system failure. A coupled multi-physics dynamical model of the FOWT was developed using the FAST-AQWA (F2A) framework, integrating aerodynamics, hydrodynamics and structural dynamics. The model was used to evaluate the performance of the designed TMD in two post-failure operational conditions: continued power generation and shutdown. Two environmental conditions were considered for each operational mode: low and high wind-wave loads. Time domain metrics adopted to assess TMD performance under varied conditions included the maximum, minimum, root mean square and standard deviation of responses, while the frequency domain indicators comprised the power spectral density peak and global root mean square. The results showed the TMD effectively reduced FOWT vibrations after a blade pitch control failure, achieving up to 63.76 % reduction in platform pitch and to 55.81 % reduction in tower top displacement, thus enhancing system safety.