Investigations On The Wave-resistance Ability And Vibration-reduction Effect Of A Spar Buoy-type Floating Offshore Wind Turbine

As one of the important directions of renewable clean energy development,offshore wind power has gradually become a research hotspot in the global wind power field.Although the prospect of offshore wind power development is broad,its development is much more difficult than onshore wind power.The key technical problem of offshore wind power is that the floating wind turbine will have a larger motion response when facing complex wind and wave environments.Therefore,how to improve the wave-resistance ability and vibration-reduction effect to ensure that the floating wind turbine system does not break down is one of the current research hotspots.In this paper,the OC3-Hywind Spar is taken as the research object.The mooring system is optimized and three schemes are proposed.The program developed based on FAST is used to calculate the motion response of the optimized model.The results of time domain analysis and frequency domain analysis prove that the three optimized schemes can effectively improve the wave-resistance ability of floating wind turbine.In the study of the clump masses,the surge motion of the floating wind turbine can be greatly restricted by the the clump masses added on the mooring lines.The research found that the location of the clump masses has a significant impact on the motion of the Spar platform and the impact of the mass of the mass is almost negligible.As the depth of the location where the clump masses mounted is increased,the better the wave-resistance ability of the wind turbine platform.In the study of the three-segmented bifurcated mooring lines,the torsional and anti-overturning capabilities of the floating wind turbine are significantly improved by designing the upper mooring lines as a three-segmented bifurcation structure.The study found that the length of the three-segmented bifurcated mooring lines has a significant effect on the wave-resistance ability while the arrangement distance of the fairlead has no significant effect.And the shorter the length of the sub-bifurcation mooring lines,the better the stability of the optimized model.Finally,when the three-segmented bifurcated mooring lines and the clump masses are combined,the results show that the combined model has better performance.In the study of the six mooring lines system,the purpose of improving the waveresistance ability of the floating wind turbine is achieved by increasing the number of mooring lines and optimizing the layout of the mooring lines.The study found that the performance of layout which has 3 mooring points and each group of mooring lines has a certain angle β is better than the performance of layout which has 6 mooring points.As the angle β becomes larger,the effect of limiting the surge motion of the floating wind turbine is better,but the improvement of the limited effect is not great.Compared with the previous two schemes,the performance of the six mooring line system is better,and it has a good suppressed effect on surge,pitch and yaw motion.