Hydrodynamic Research Of New TLP Type Offshore Wind Turbine With A Series Connected Pontoon On Tendons

In recent years,with the deterioration of the atmospheric environment,excessive emissions of greenhouse gases such as CO₂ and the shortage of energy resources,there is an urgent need to develop green clean energy.As an ancient clean energy,wind energy has developed rapidly in recent years.At present,the study of onshore wind power has been completed,while the study of offshore wind power are developing rapidly.As China’s energy demand is mainly concentrated in the eastern coastal areas,so the research of offshore floating wind turbine has great significance.In the sea area which depth more than 50 m,the TLP’s type wind turbine has greater advantage.As a result the TLP is often selected as the sea floating wind turbine foundation.As the tension leg platform is an semi-rigid and semi-compliant structure,it’s vertical movement is small,while the horizontal movement is larger.However,the offshore wind turbine is subjected to a large level of wind load,therefore it is important to effectively suppress the horizontal motion response of the wind turbine platform to improve the stability and power generation capacity of the TLP type wind turbine.In this paper,the suppressing effect of the wind turbine horizontal motion response has been discussed in detail after connected a pontoon on tendons.the influence of different pontoon parameters was explored by frequency domain and time domain simulation method.Then,the adaptability of new TLP type offshore wind turbine in different water depth was verified.Firstly,the mooring stiffness matrix,mooring damping and viscous damping of the new TLP type offshore wind turbine were deduced,and the motion equation in the frequency domain was constructed.the influence of different pontoon parameters on the horizontal motion of the wind turbine was analyzed by pseudo-static analysis,The results show that enlarging the buoyancy of the pontoon,raising the position of the pontoon in tendon can improve the horizontal restoring forces of wind turbine significantly.Secondly,the motion response of the new TLP type offshore wind turbine was discussed under different wave height and wave incidence angles based on the ANSYS-AQWA time-domain simulation model,and the relationship between the tether mode and the motion response suppression section of the wind turbine was studied by modal analysis.The results show that raising the position of the pontoon in tendon,reducing the buoyancy of the pontoon can decrease the period of tether mode,and then the motion response suppression section can covers the common wave range.Thirdly,the hydrodynamic of new TLP type offshore wind turbine with a series connected pontoon on tendons under the working condition of a sea area in the South China Sea was researched,and the adaptability under the different water depth conditions of new TLP type wind turbine is explored.The results show that connected pontoon on tendons can suppress the surge response of the TLP type wind turbine.With the increase of the water depth,the surge response suppression section will be shifted to the left and the new TLP type wind turbine will no longer apply.Finally,because the conventional time domain analysis software can not deal with the tendons added a pontoon very well,and can not calculate the motion state of the pontoon,therefore a time-domain simulation program was coded in this paper based on the MATLAB software.It can consider the multi-body coupling effect of pontoons and wind turbine foundation,and can calculate the movement state of all pontoons at any time.