Vibration control of a pentapod offshore wind turbine under combined seismic wind and wave loads using multiple tuned mass damper

The dynamic characteristics and coupling mechanisms of a bottom fixed offshore wind turbine (OWT) with a pentapod substructure under combined seismic, wind, and wave conditions are analyzed. A passive control method of a tuned mass damper (TMD) is then applied. The influence of the TMD parameters on the control effects of the OWT is investigated, and the feasible parameters for the vibration mitigation are recommended. Then, a multiple tuned mass damper (MTMD) with abundant tuning frequencies is developed in view of the limitation of the TMD on the vibration control. Both the local and global responses of the OWT can be significantly decreased by the MTMD, validating its wide applicability relative to the TMD. Furthermore, suggestions for designing the MTMD for an OWT under the seismic cases are summarized.