Study On Aerodynamic Performance Simulation Of Wind Turbine Smart Blades

With the development of wind power industry,the power capacity of wind turbines and the size of rotors have increased significantly,and the atmospheric turbulence around blades become more complex.The unfavorable load would fluctuate in higher frequency,which could further aggravated the fatigue load and extreme load.Accordingly,it is easier to cause serious fatigue damage and increase the cost of operation and maintenance of wind turbine.In order to study the impact of trailing edge flap(TEF)on wind turbine smart blades,the research is carried out around unsteady aerodynamic model and active load-alleviation control method of smart blade,and the main work and conclusions are as follows:(1)To accurately calculate the unsteady aerodynamic performance of wind turbine smart blades,a modified unsteady blade element momentum(BEM)model for wind turbine smart blades was developed based on unsteady BEM theory,where the National Renewable Energy Laboratory(NREL)5MW reference wind turbine was selected as the study object.Then the unsteady aerodynamic performance of the present model is analyzed.Results show that the present model can efficiently simulate the unsteady aerodynamic performance of wind turbine smart blades:under steady wind conditions,the unsteadiness around the airfoils and the overshoot of wind turbine performance can be simulated;under the condition of the changing TEF angles,the impact of TEF on smart blades can be simulated.(2)To alleviate the unfavorable load of large wind turbine,the pitch controller and the TEF controller of wind turbine blades were designed based on x-LMS algorithm.The control performance and control effect were analyzed in normal turbulent model(NTM)wind condition,results for single blade show that the present controllers can reduce the fluctuation of flapwise blade root moment by adjusting pitch angles and TEF angles quickly,which implies that the controller based on x-LMS algorithm can be used in real-time active load-alleviation control of wind turbine blades.(3)To maximize the active load-alleviation capacity of wind turbine smart blades,the load-alleviation capacity of individual pitch control method and individual flap control method in different frequency zones was analyzed.After that a compound active load-alleviation control method was proposed,which aiming at suppressing the fluctuation of flapwise blade root moment in low frequency and high frequency.Then time series results and frequency domain results were obtained in different NTM wind conditions.Results for three blades show that the present method can effectively reduce the standard deviation of flapwise blade root moment,the power spectral density(PSD)of flapwise blade root moment at IP and 2P frequency,and the average variation of pitch angle and TEF angle.It can reduced the fatigue load of blade significantly.