Research On Aerodynamic Design Method Of 10MW Floating Offshore Wind Turbine

As China accelerates the realization of carbon-peak and carbon-neutral targets and adjusts the energy structure to green and low-carbon transformation,China’s wind power industry will usher in unprecedented development opportunities and have a very broad development prospect.Wind turbine is the core equipment of wind power generation.The wind energy conversion efficiency of the wind turbine is closely related to the chord,twist angle and airfoil distribution.The optimal design of blades is the key to the aerodynamic design of wind turbines.Currently,the widely used method for blade design is the Wilson method,which usually specifies the design blade tip speed ratio directly,without considering the control laws during the actual operation of the unit.This will result in the design optimization results being only optimal under design conditions.In this dissertation,the overall design method and improved Wilson method for wind turbines are studied.A 10MW wind turbine is designed,and a joint simulation method of Bladed and Simulink is established to study the transient characteristics and low voltage ride through characteristics of the turbine.The specific research work includes:(1)Based on the Blade Element Momentum theory,considering the influence of the correction when the axial induction factor is large,tip loss,hub loss and the blades 3-D rotating effect on the aerodynamic performance of the wind turbine,the aerodynamic performance analysis program of the wind turbine was compiled using Python,and the accuracy of the calculation results of the program is verified.(2)Taking the DU99W405 as the reference airfoil,a new airfoil with a relative thickness of 50%was designed.Based on the characteristics of offshore wind resources and the design objectives of floating wind turbines,the basic design parameters for a 10MW unit have been determined.Based on the Wilson design method,the initial chord length and twist angle distribution of the blade are calculated,and the root and tip portions are modified according to the requirements of the actual blade geometry to ensure a smooth geometric shape.(3)A new blade optimization design model is proposed.Firstly,the optimal tip speed ratio of the wind turbine is iteratively calculated,and the Weibull model is used to calculate the distribution probability of wind speed in a year.The control law of the wind turbine is preset.Combined with genetic algorithms,the optimal design model of the blade is established with the maximum annual power generation as the optimization goal,and the changes in the chord length and twist angle of the blade as the design variables.(4)The Bladed was used to model the blades designed in the dissertation,build a complete wind turbine model,and calculate the aerodynamic performance of the entire wind turbine.The calculation results show that the wind energy utilization coefficient of the blade designed in this dissertation reaches 0.4861,which is 1.04%higher than that of the traditional Wilson method,thereby verifying the effectiveness of the optimization design model proposed in this dissertation.(5)The dynamic response characteristics of the wind turbine under a given platform motion rule are calculated.The results show that when the wind turbine operates in surge,pitch,and coupling motions of surge and pitch,the power and thrust of the wind turbine will fluctuate significantly.(6)Based on the technology of dynamic link library and socket data interaction,this dissertation established a joint simulation platform of Bladed and Simulink,and simulated the low voltage ride through process of wind turbines.The results show that the blade load will significantly change during the low voltage ride through process,and the blade tip displacement will significantly increase.In this dissertation,a set of design and simulation methods for 10MW wind turbines has been established,and dynamic characteristics simulation in marine environment and under low voltage faults in the power grid has been conducted.The research results can provide a reference for the design and overall simulation of large offshore wind turbines.