Dynamic and Power Generation Features of A Wind–Wave Hybrid System Consisting of A Spar-Type Wind Turbine and An Annular Wave Energy Converter in Irregular Waves

Combining wave energy converters (WECs) with floating offshore wind turbines proves a potential strategy to achieve better use of marine renewable energy. The full coupling investigation on the dynamic and power generation features of the hybrid systems under operational sea states is necessary but limited by numerical simulation tools. Here an aero-hydro-servo-elastic coupling numerical tool is developed and applied to investigate the motion, mooring tension, and energy conversion performance of a hybrid system consisting of a spar-type floating wind turbine and an annular wave energy converter. Results show that the addition of the WEC has no significant negative effect on the dynamic performance of the platform and even enhances the rotational stability of the platform. For surge and pitch motion, the peak of the spectra is originated from the dominating wave component, whereas for the heave motion, the peak of the spectrum is the superposed effect of the dominating wave component and the resonance of the system. The addition of the annular WEC can slightly improve the wind power by making the rotor to be in a better position to face the incoming wind and provide considerable wave energy production, which can compensate for the downtime of the offshore wind.