Use of a Wave Energy Converter as a Motion Suppression Device for Floating Wind Turbines

Floating offshore wind turbines (FOWTs) are subjected to large amplitude motions that induce greater loads on components and reduce aerodynamic performance. One approach to counteract this has been to use passive damping systems for FOWTs to dissipate the wave-induced energy and therefore reduce the global platform motions. This paper proposes that rather than discard this energy, a wave energy converter (WEC) is utilized on the floating platform to absorb it. A study is carried out on a floating vertical axis wind turbine (VAWT) combined with WEC moving in heave. A range of damping and stiffness coefficients are applied between the FOWT and WEC to establish strategies for two cases: maximum motion reduction and maximum energy extraction. The results and conclusions obtained are presented in terms of modifying the WEC natural frequency, damping and stiffness values.