Compared with fixed offshore wind turbines, the vibration problem of floating offshore wind turbines is particularly prominent, and further reduction of the vibration of floating offshore wind turbines has become an engineering challenge. In order to solve this problem, a novel vibration suppression device, inerter-based absorber (IBA) is introduced, and the vibration control of semi-submersible offshore wind turbines is studied. A comprehensive optimization method, namely the structure-immittance approach, is utilized to design the IBA in a systematic way. In order to search for the optimum vibration suppression performance, a simplified dynamic model of the semi-submersible offshore wind turbine, and the IBA dynamic equations are established using D’Alembert’s principle. Simultaneous suppression of the vibration response of the floating platform and tower of a semi-submersible offshore wind turbine is realized using the dual IBA control strategy. Furthermore, by implementing the optimum IBA in the OpenFAST software, the vibration suppression benefits of the dual IBA compared with the dual tuned mass damper (TMD) are verified under the coupling effects of wind and waves. The results show that the vibration control performance of the dual IBA control strategy is significantly better than that of the single one, and that of the dual IBA is better than that of the dual TMD. In addition, under the condition of achieving the same suppression performance as the TMD, IBA installed at the nacelle and the platform can respectively decrease the required absorber mass by 23.9% and 32.2%, which can greatly reduce the manufacture cost of the device.
