Study On The Motion Characteristics Of Spar Floating Foundation For Offshore Wind Turbine

As one kind of renewable clean energy, the wind energy is getting more and more important in the national energy strategy, moreover. Therefore, the research on the dynamic response of floating wind turbine has vital significance.This article first summarized domestic and foreign research development regarding the floating wind turbine, introduced the theory on the calculation of environment loads. Based on the 5MW wind turbine of NREL, a new type of foundation for floating wind turbine was designed in concept. According to the blade element-momentum theory and the catenary method, procedures were composed on how to calculate the aerodynamic load and the restoring force provided by mooring system.Considering the matrix of viscous damping and restoring of mooring system, the frequency domain analysis was carried out. The influence of angle of wave with water depth to its motion was also studied. Considering the coupling effects of wind turbine to foundation and mooring system to foundation, the dynamic response of floating wind turbine in regular wave was studied. On the joint action of wind, wave, current, with consideration of the coupling effects of wind turbine to foundation and mooring system to foundation, the time domain analysis was performed by DeepC for the dynamic response of floating wind turbine in stochastic wave.The results showed that: First, the angle of wave had significant influence on the dynamic response of pitch and surge, the water depth also on surge, the floating wind turbine was more apt for deep water. Second, the elevation of wave performed important affection to the dynamic response of heave when the period of wave was close to the natural period of heave, however, the restoring force of mooring system could prevent the resonance vibration. Third, before the speed of wind reached 25m/s, the wind turbine could work normally under state 1, state 2, state 3, but the wind turbine should stop under state 4 whatever the wind speed was. Therefore, the Spar floating foundation has certain value for offshore wind turbine.