An evaluation of mooring system in a wind-wave hybrid system under intact and accident states

Abstract

To improve power capture efficiency and reduce cost for marine renewable energy resources, a new hybrid wind-wave energy system named Column-Torus Semi (CTS) was presented, which is a semi-submersible type floating wind turbine with cylindrical tori as point absorbers for wave energy. Wave tori bring challenges to the load carrying capability of the mooring system in intact and accident states. To evaluate the dynamic performance of the mooring system, an aero-hydro coupling analysis and a series of model tests were carried out under operating and extreme conditions. Tori dimension is considered to assessment its scale effect. Evaluation method for numerical analysis is validated by model tests and reliable references. The result shows that mooring tensions at windward side are increased to a higher level because of the existence of wave tori, but they are not very sensitive to the tori's size as considered in this study. According to the relative motion assessment, efficiency of power generation from the CTS system with larger tori is superior to that with small size.