Research On Maximum Power Point Tracking Control Strategy Of Floating Wind Turbine

The development of renewable energy is a major energy strategy that supports china to achieve the 30·60 carbon neutral and carbon peak goal.Wind energy is one of the most important renewable energy sources,the offshore wind energy reserves of china reach 750 million kilowatts,but currently less than 25% is being developed,and there is a huge potential for development.Compared with the offshore waters,the wind conditions in the deep sea are relatively stable,the wind energy density is high,and they are not easily restricted by the location of the seas.This is one of the mainstream trends in the development of global offshore wind power.Floating wind turbines are currently the most effective wind power equipment for the development of deep sea wind energy.However,they are subject to the combined effects of random wind and waves all the year round,the operating conditions are complex.Moreover,the floating design will cause the floating wind turbines to produce larger surging and pitching movements under the combined effects of wind and waves,which aggravate the wind shear effect of the blades,increase the torsional vibration of the wind turbine transmission system,and then deteriorate the stability of the power generation,which significantly affects the performance of the whole machine.Therefore,this thesis aims at the maximum wind energy capture problem under the rated wind speed of floating wind turbines,combined with the overall system dynamics model of floating wind turbines,carries out research on the maximum power tracking control of floating wind turbines,and improves floating wind turbines under the combined action of wind and waves.The power generation efficiency is of great significance for ensuring the operating performance of floating wind turbines.The thesis takes 5MW floating wind turbine as the research object.short-term random wind speed estimation and maximum power point tracking control are considered,combined with the flexible structure such as tower and blades and external load excitation,the system dynamics model of floating wind turbine is established.The short-term random wind speed estimation,the design and parameter sensitivity analysis of maximum power tracking control system,and the influence of working conditions on the robustness of floating wind turbine are studied.The research results have certain reference significance for the design of the maximum power tracking control system of offshore floating wind turbines.The main research contents of the thesis are as follows:(1)Dynamic model of floating wind turbine system.Taking 5MW floating wind turbine as the research object,the optimization method of the weight and threshold parameters of the wind speed observer is proposed;Considering the optimal speed tracking of the floating wind turbine system and the suppression of system buffeting,a maximum power tracking control method for floating wind turbines based on PID-second-order synovial hyperplane is proposed;Combining the flexible structures of wind turbine blades,tower and moorings,the external load excitation of aerodynamic and hydrodynamic,the floating wind turbine system dynamic model is established.(2)Short-term random wind speed estimation for floating wind turbines.Based on the floating wind turbine system dynamics model,the wind speed estimation error under different wind speed observer parameters is analyzed,and the optimization method of the weight and threshold parameters of the floating wind turbine wind speed observer under short-term random wind speed is proposed;The effect of short-term stochastic wind speed estimation under the same working condition and the generalization of the wind speed observer model under multiple working conditions are analyzed.(3)Comparison analysis of parameter sensitivity and control performance of the maximum power tracking control system.Based on the system dynamics model of the floating wind turbine,the influence of the parameter change of the maximum power tracking control system based on PID-second-order sliding mode on the power generation,high-speed torque peak and fluctuation of the floating wind turbine is analyzed;The overall power generation efficiency and power generation of the floating wind turbine,the peak torque and fluctuation of the high-speed and low-speed torque of the transmission system and tower base bending moment are compared and analyzed.(4)The influence of the operating conditions of individual wind(still water)and the combined wind and waves on the robustness of the maximum power tracking control system of floating wind turbines.Under still water conditions,the effects of changes in average wind speed,turbulence intensity and air density on the overall power generation efficiency of floating wind turbines,torque peaks and fluctuations of the transmission system are analyzed;the effects of wind load and wave load changes on the overall power generation efficiency and power generation of the floating wind turbine,and the high-speed torque peak and fluctuation are analyzed.