Flexible Multi-body Modeling And Load Characteristics Analysis Of Wind Turbines

Combination of multi-body modeling and experimental validation is currently employed at the preliminary stage of design of wind turbines due to the steadily increasing size and manufacturing costs.In recent years,with the establishment of International Wind-turbine Certification Standard and the progress of multi-body dynamics emulation software,the multi-body emulation model implementation of wind-turbine is undergoing a significant change,evolving from traditional simplified multi-rigid-body modeling to flexible multi-body modeling techniques gradually.Presently,there is a large gap betwen our country and abroad in wind turbine modeling.Thus bring limitations to describe the dynamic behavior of wind turbine in detail.With all of those in consideration,it is necessary to develop the wind turbine modeling techniques,which will have an important significance in designing,experimental validation,operation analysis and structural optimization of wind turbines.Simulation analysis in preliminary stage of design will also provides instructions in validation and improvement at final stage.The subject of this thesis is sponsored by National Supporting Plan Project.Three multi-body dynamic models of wind turbine with different complexity are established and the dynamic characteristics of each model are analyzed under external wind conditions.The main research contents can be summarized as follows:1.An aerodynamic-elastic-control coupling simulation model of a 5 MW offshore wind turbine without gearbox is established to research its dynamic response characteristics.The dynamic load characteristics of wind turbine under normal turbulence model,extreme turbulence model and idling working condition is studied in accordance with current industrial standards IEC61400-1.We chosed a conventional variable-speed,variable blade-pitch-to-feather configuration as the pitched-control strategy.And curves of hub wind speed,blade-pitch angle and load spectrum are obtained.2.Combined with concrete examples,comparative analysis of time-varying meshing stiffness in SIMPACK simulation analysis and by using cantilever beam theory and potential method,or in accordance with current industrial standards is presented to validate the applicability of the multibody model.3.A multi-body dynamic model of the first planetary gear train of a 7 MW wind turbine is built.In the model,the planet carrier was considering as flexible body and the gears were split into five smaller segments.The deformation of the planet carrier and the load sharing behavior is analyzed when gearbox is at rated input power and speed.4.To get sufficient insight in the dynamics of the entire wind turbine dive train,a multi-body dynamic model include detailed gearbox is established.Dynamic load characteristics of key components in gearbox under external wind load are discussed.Gear modification,bearing stiffnesses,gear mesh stiffnesses,key component flexibilities are taken into account in the multibody model.Thesis research can provide a reference for the wind turbine design,operation analysis,structural optimization,authentication.