Research On Hydrodynamic Performance Of Semi-submersible Wind Power Installation Platform

Our country has a long coastline,and abundant offshore wind resources,wind resources in the eastern coastal areas reached 760 million k W.The National Energy Administration and the National Development and Reform Commission issued the "Energy Production and Consumption Revolution Strategy(2019-2030)" goals,which can be seen in the country’s efforts to develop the clean energy industry,In 2019,the domestic offshore wind power capacity was about 10.7GW,and the bidding amount was about 15 billion yuan,In 2020,the total installed capacity of offshore wind power reached 184 million k W.At present,the main installation in our country is mostly 5MN and 6MN offshore wind generator set,for the more powerful generator set is also small-scale installation.Most of the newly built offshore wind power installation platforms have a lifting capacity of between 1000 tons and 1500 tons.According to the current good news in the market and combined with the local planning during the 14 th Five-Year Plan period,there is still a strong demand for offshore wind power in the future.The installation of offshore wind power is easily affected by the environment,which will affect the hoisting accuracy and thus cannot be constructed.Therefore,it is of great significance to study the hydrodynamic performance and motion response of offshore wind power installation platform.The main research contents of this thesis are as follows:(1)The semi-submersible wind power installation platform is mainly composed of main float tank,auxiliary float tank,main column and outboard column.The calculation model of the platform is built to study the hydrodynamic performance of the platform in different directions.The platform added mass,radiation damping,first order wave force and amplitude response operator(RAO)were calculated.The results show that the asymmetric shape of the platform has little influence on the amplitude response operator.The hydrodynamic performance of the platform is better when the wave frequency is high frequency than that when the wave frequency is low frequency,and the platform should avoid operating at low frequency.(2)Aiming at the influence of different mooring modes on the hydrodynamic performance of semi-submersible wind power installation platform,the six-degree-offreedom motion response of semi-submersible wind power installation platform under catenation mooring and dynamic positioning mooring was studied,and the general rule of motion response of semi-submersible wind power installation platform was obtained by analyzing the influence of different incident angles of wind and wave flow on the platform motion.The results show that the motion control of dynamic positioning mooring platform is better than catenary mooring in the longitudinal direction.The movement amplitude of dynamic positioning system is smaller than that of catenary mooring.(3)Aiming at the hoisting accuracy of fan impellers on semi-submersible wind power installation platform,a hoisting system calculation model was established to study the motion response of fan impellers under two hoisting modes of single and double cranes.By analyzing the influence of different incident angles of wind and wave flow on fan impellers’ motion,the general rule of fan impellers’ motion response was obtained.The results show that the impeller of the fan operated by the double crane is less than that of the single crane.The impeller of the fan operated by the double crane is better than that of the single crane in the swaying direction.(4)In view of the influence of environmental factors and key factors in the lifting process on fan impeller motion,a fully coupled model of lifting system-fan impeller and platform was established to study the motion response of fan impeller under wind load,flow load,fan impeller height,boom elevation and boom rotation speed,and to summarize the general laws affecting fan shaking.The results show that the fan impeller motion increases obviously with the increase of wave period,and the increase of wind and velocity will lead to the increase of the fan impeller longitudinal and vertical motion.Fan impeller height and boom rotation speed increase with the increase of height,speed and wave period,fan impeller motion amplitude increases.Different numbers of cables produce different motion responses to the fan impeller,and the motion response of three cables is not significantly reduced compared with two cables under single crane operation,while the motion response of two cables is not significantly reduced compared with one cable under double crane operation.