Structural And Dynamics Analysis On The Pitch System Of MW Grade Wind Turbine

As an important part of horizontal axis wind turbine, Pitch system’s main role is toadjust the power by adjusting pitch angle. For researching the work performance andsafety performance of pitch system, the dynamic characteristics of wind turbine in pitchwas analyzed by the multi-body dynamics method, and Finite Element Analysis andfatigue analysis of pitch system had been done. The method in this paper providedtechnical reference for design and checking of the wind turbine pitch system withengineering value.The main research included following work:①This paper studied the aerodynamic theory of wind turbine under variable pitch,it illustrated the basic structure and function of wind turbine pitch system.②According to the German Society of Germanisher Lloyd (GL) certification,topological graph of the wind turbine and the pitch system was drawn. On the basis oftopological graph, wind turbine dynamics model was built in SIMPACK. Automaticpitch control model was established. Wind simulation model was constructed accordingto the IEC specification. Whole machine co-simulation of air-flexibility-control in pitchconditions was completed. Time domain analysis results showed curves of pitch angle,wind turbine power, forces and moments in blade root.③According to mechanical characteristics of wind turbine pitch system, thispaper proposed a method using compression-only3D-spar element link10to simulatepitch bearing roller. Then finite element model of wind turbine pitch system had beenestablished to analyze. Results showed the stress nephogram of pitch system and contactstress distribution of pitch bearing under unidirectional and pitch loads.④The fatigue analysis model of pitch bearing was established, and the fatiguestress of pitch bearing was calculated by using Finite Element Method. Then the fatigueload spectrum was simulated by using rainflow counting method and the S-N curve formaterial was revised. According to the fatigue cumulative damage theory, it calculatedthe fatigue damage of pitch bearing in the design life.