The mooring system is a key component connecting a floating windturbine to the seabed. For floating structures, the horizontal motions arecrucial. The design of a mooring system is required to maintain thefloating wind turbine within a certain radius. The low frequency (LF)excitation caused by the irregular wave may induce large resonantmotion responses of a floating wind turbine. As we know, the naturalfrequency of a floating wind turbine is mainly depended by the staticrestoring force of the mooring system connected with the floating windturbine. Besides, the mooring-induced damping could play animportant role when the resonant motion happens. Thus, the mooringsystem selection can have significant influences for station keeping androtational oscillation control of a floating wind turbine.In this paper, considering a semi-submersible wind turbine worked inthe South China Sea, the dynamic responses of the wind turbineplatform and the effects of three types of mooring systems with thesame cost are studied. Different mooring patterns with eight identicalchain cables are considered. The platform motions are influenced bythe combined effects of waves and the mooring system. Therefore, inthis study, the platform motion responses are analyzed by nonlinearcoupled method in time-domain. Besides, the hydrodynamics of thewind turbine platform are simulated by three-dimensional potentialtheory, and the hydrodynamic forces on the mooring system arecalculated by Morison’s equation.Through the numerical simulations, the time-domain and frequencydomainresponses of the semi-submersible wind turbine platform areinvestigated. The influence of different mooring system types on thehydrodynamic response of the semi-submersible wind turbine platformare compared and analyzed. The conclusions of this study could serveas a reference for the development of semi-submersible wind turbinesin the South China Sea.
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