| Energy problem is one of the most serious problems faced by all countries in the world.Many disadvantages of conventional fossil energy and the shortage of reserves remind people that the development of new energy is urgent.Wind energy,as a kind of renewable energy for sustainable development,is widely valued.Wind turbine is the core equipment of wind energy utilization and development.It is of great significance to carry out wind load simulation and fatigue life reliability research of wind turbine blades to promote the development of wind energy.Therefore,this paper first obtains the load environment of the wind turbine structure by comparing a variety of three-dimensional wind load simulation methods.On this basis,a multi-body dynamic model of wind turbine structural load simulation is established,and the calculation method of blade dangerous load is studied.Finally,combined with the structural reliability analysis method,the reliability calculation process of blade fatigue life is studied,and the reliability results of wind turbine blades under different service conditions are obtained.The main research contents of this paper include:(1)Simulation of fluctuating wind speed fieldFirstly,the spectrum representation method and auto-regressive model are used to simulate the three-dimensional fluctuating wind field.Then,the difference of simulation accuracy,calculation efficiency and dimension of random variables between them is compared with Davenport wind spectrum model.The results show that the number of random variables in wind load simulation can be greatly reduced by using the random function to represent the random variables in spectrum representation and the spectrum representation method based on random function is more accurate in the calculation of wind speed self power spectrum and cross power spectrum.(2)Wind turbine load simulation and analysisAccording to the theory of blade momentum,the procedure of calculating the aerodynamic load of wind turbine is deduced.Based on the three-dimensional wind field simulation results of wind turbine combined with Kaimal wind spectrum model and combined with fast software,the load simulation of NREL 5MW wind turbine under different wind conditions is carried out.The simulation results of shear force,moment,output power and pitch angle of blade root are obtained,and the influence of different wind conditions on the simulation results is analyzed.On this basis,the fatigue damage calculation of subsequent wind turbine blades is carried out.(3)Fatigue damage calculation and reliability analysis of wind turbine bladesBased on the bending moment load of wind turbine blade in all directions,combined with the material properties of blade structure shape,the equivalent stress load spectrum of blade root dangerous section is obtained.Combined with rain flow counting method,Goodman curve,Miner linear cumulative damage criterion and wind speed distribution in accordance with Rayleigh distribution,the fatigue life of wind turbine root can be obtained.The rationality of this method is illustrated by different wind fluctuations.Due to the randomness of the wind load,the normal and log-normal distribution of the fatigue life are fitted,and the limit state equation of the fatigue life is given,and the FORM method can be used to calculate the fatigue life reliability of wind turbine blades. |
PDF Full Text Request