Effects of WEC design parameters on fully coupled responses of a Barge-type wind-wave-integrated floating energy system

The WinHyS comprising of the FOWT and WECs is a prospective solution to achieving motion stability improvement and energy utilisation efficiency enhancement. The dynamics of WinHyS is related to the WEC's design properties including the shape and parameters of the PTO system. A fully coupled analysis tool is developed for aero–hydro–servo-elastic analysis. It is investigated that platform motions for WinHyS are alleviated with hemispherical WEC under three load cases. The variation ranges of platform roll can be reduced by 57.41% under the 18 m/s wind speed, while corresponding reductions of cylinder- and frustum-shaped WECs are 56.85% and 56.99%, respectively. The output power for the hybrid system is achieved the most significantly by up to 2.45% with the integration of cylindrical WECs under the 18 m/s wind speed condition. Moreover, a relatively larger PTO damping is more beneficial in reducing platform roll, while the influence on platform pitch depends on the environment condition. Conversely, a smaller PTO damping can contribute more to the total power. Therefore, the WinHyS with hemispherical WECs and a moderate PTO damping is more likely to simultaneously achieve better performance in platform motion and power production, which is also evidenced by the dynamic behaviours under the extreme sea condition.