Investigation on the design and hydrodynamic performance of 15MW Spar-type floating offshore wind turbine platform

Objectives In order to develop large-scale floating offshore wind turbine, provide a safe and economical design scheme for floating wind turbine platforms, and study the hydrodynamic performance of a new type of floating foundation for wind power generation to achieve effective utilization of deep-sea wind energy. Methods For the 15MW floating wind turbine, a new design scheme of spar floating wind turbine platform was proposed, and the stability and economy of the platform were analyzed. Based on the potential flow theory, the frequency domain hydrodynamic calculation of the platform was carried out, and the wave loads and motion responses characteristics of the platform under different wave direction were studied. The blade element momentum method was applied to calculate the aerodynamic load of the impeller and equivalent it to the wind coefficient, thus the time-domain responses of the platform under the combined effect of wind, wave and current under different working conditions were calculated. At the same time, the force situation of the mooring line was analyzed. Results The results show that the platform heave, roll, and pitch have peak points at the natural frequency of the platform motion, and the positions of occurrence are all far from the main energy region of the waves. Under the action of wind, wave, and current, compared to the working conditions, the maximum pitch angle of the platform under extreme conditions is smaller, but the amplitude of maximum surge and heave，as well as the maximum mooring tension are greater than the working conditions. Conclusions It has been proven that the new designed Spar-type floating wind turbine platform has good stability and hydrodynamic performance. Under the designed environmental loads, the platform responses and mooring force can meet the requirements of the specifications, and can ensure the safety and stability of wind turbine.