Safety And Reliability Of The Composite Bucket Foundation-Tower-Wind Turbine In Offshore Wind Power During The Transportation And Installation Process

With the continuous development of social economy,offshore wind power has attracted much attention as an important part of energy framework in China.The composite bucket foundation(CBF)is a new foundation form of offshore wind power.Different from the transportation and installation technology of traditional offshore wind power infrastructure,the overall transportation and installation technology of the CBF is efficient,low-cost and large-scale for offshore wind power.Through theoretical analysis,model tests,numerical simulations and prototype observations,this paper systematically studies the static and dynamic stability of the air-floating structure,the safety of the transportation and installation technology of the entire process,application prospects in the deep sea.The main research contents include:1.We established a simplified theoretical model of the air-floating structure and proposed that the damage angle,initial stability height and restoring moment were the criteria for the static stability of the air-floating structure.We deduced the air-floating structure response function in regular waves and the response reduction coefficient of air-floating response.We carried out the free attenuation,wave and wave-current coupling model tests of the air-floating structure and the solid-floating structure,and determined the relationship between the natural period and linear damping coefficient of the air-floating structure and the solid-floating structure,and the floating mode of the double-cabin in front of the CBF.The experiment revealed that the motion response of the air-floating structure under the same wave and current conditions is smaller than that of the solid-floating structure.The motion response of the air-floating structure increases with the decrease of the draft height,and the reduction coefficient increases with the increase of the draft height.2.Based on the model tests of the overall transportation of CBF,a prediction response model considering the velocity,wave height and wave period of the overall transportation was established;the overall transportation model under non-collinear conditions were carried out.Numerical simulation research revealed the motion response law of the overall transportation under different wave directions and flow directions,and put forward the floating safety of the overall transportation using the maximum horizontal acceleration and heave acceleration of the nose as the control index.The flexible control strategy has guided the overall transportation based on the Dafeng offshore wind turbine,ensuring the safety of the project;the prototype observation data verifies the correctness of the model tests and the numerical simulation methods,and clarifies the safety factor of the overall transportation control index The value is taken to improve the response prediction model of wind-wave-flow in nacelle acceleration.3.The theoretical analysis and model tests of the overall installation under the supporting condition of are carried out,and the control condition of the overall installation is determined when the top traversed the water.The numerical simulation study on the overall installation under different draft heights was carried out,and the bimod periodic distribution law of the pitching angle RAO of the CBF top was revealed.The pitching angle of the top was determined as the control index of the overall installation,and the wave height condition and the maximum inclination value were defined.The safety control strategy of the whole cylinder foundation was formulated,which guided the overall installation of Dafeng overall installation to ensure the safety.Based on the prototype observation data,the safety margin of the water subsidence control index of the CBF was optimized.4.For the CBF structure of the large-capacity wind turbine in the deep ocean,a split transportation plan was developed,and a numerical simulation study of the split transportation of the CBF under non-collinear conditions was carried out,and a feasibility and safety control strategy for the split transportation of the CBF was proposed.We developed a suspension-cable combination scheme suitable for deep-water installation of CBF.Numerical simulation studies were carried out on the deep-water installation under different draughts.The distribution of the pitch angle RAO of the CBF was revealed and demonstrated.For the safety and feasibility of the deep-water installation technology of the CBF,a recommended deep-water installation construction operation process is proposed.