Dynamics Analysis Of Large Wind Turbine Variable Pitch System

With the increasement of the social demand for energy, wind energy, as a kind ofrenewable energy, is paid more attention to all around the world. In the aspect of windpower, large wind turbines has become the mainstream, but its dynamic characteristic iscomplicated in the process of work, Especially the load fluctuation of big wind turbinesbecame more and more obvious as a result of wind shear factors, make the reliability ofwind turbines and fatigue life be affected. The dynamics of wind turbines variable pitchsystem is analysed and the fatigue life of key parts is calculated by us. The basis of windturbines structure optimization and reliability design is provided. The main researchcontents include:(1) The wind power utilization rate of wind turbines was deduced by air dynamic andthe principle of variable pitch system control wind turbines power is expounded(2) According to the theory of wind turbines blade design, the blade parametricmodeling program is designed by the function of NX second development.Then thevariable pitch system model is builded by the drawings of the2mw wind turbines.(3) The two-dimensional flow field of airfoil model is builded by air dynamic and thewind turbines blade aerodynamic force is calculated.Compared with the calculation resultsof BLADED software，the method to calculate the aerodynamic force of blade was provedto be right.(4) The force of wheel hub of variable pitch system is analyzed，the load is calculatedby using analytical method in the process of variable pitch. Variable pitch process issimulated by using ADAMS software under the rated wind speed. Compared with theresult of analytical method，the simulation load was proved to be right. The reference forthe transient analysis and fatigue calculation is provided by the load of wheel hub curve ontime.(5) Using the load curve about time，the transient dynamic of wheel hub is analyzedby using ANSYS software，and stress concentration parts of the wheel hub, the maximum stress and stress amplitude is determined.The life span of the wheel hub is estimated byaccording material fatigue life curve.