Experimental study on the effects of an array of concentric wave energy converters on the dynamic of semi-submersible floating wind turbine

The concept of combined wave energy converters (WECs) with floating offshore wind turbines (FOWTs) has attracted significant research interest due to its potential for lower generation costs. The motion characteristics of floating platforms and the power performance of WECs have become two major points of concern among scholars. This paper proposed a combination of the Windfloat FOWT with an array of concentric rocker-arm type WEC, and model tests were conducted to investigate the impact of the WEC array on the motion of the semi-submersible platform. Experiments under regular waves reveal that when the wave period approaches the natural period of the WEC, the heave motion of the platform will be amplified by the WEC array. The increase in the system's waterline area and the absorption of wave energy around the platform by the WECs lead to the decrease of surge motion and pitch equilibrium displacement of the platform, and an increase in surge equilibrium displacement. Power take-off (PTO) damping and rotor thrust were also simulated in the experiments, the results indicate that the influence of rotor thrust on the hybrid system is much greater than that of the WEC array, and adjusting PTO damping can effectively control the impact of the WEC array on the motion of the FOWT.