Seismic Dynamic Characteristics And Structural Damage Analysis Of Large Wind Turbines

Energy is the driving force for the development of modern society and human civilization.With the depletion of fossil energy and the growing problem of environmental pollution,the development and utilization of new energy is becoming more and more urgent.Among them,wind energy,as an important part of green renewable energy,is gradually receiving the attention and support of governments by virtue of its large reserves,abundant sources,safety and reliability,and zero emissions of greenhouse gases.China’s southeast coastal areas and the "Three North" region are rich in wind energy and are located in earthquake-prone areas.The towering wind turbine tower structure is a typical mechanical structure with a large concentrated mass of slender flexible elastomer on the top,compared to traditional buildings.The structure is highly different and is highly susceptible to seismic loads.Therefore,this paper uses NREL open source software package as a computing platform,combined with TurbSim,AeroDyn,FAST and Seismic,to study the structural dynamic response of wind turbines with different wind speeds,different earthquakes(waveforms,magnitude)and different sites.Then based on ABAQUS,tower modal and buckling analysis were performed.The main research contents and conclusions of this paper are as follows:1.Based on 8 different wind speeds,select IEC Kaimal turbulence wind spectrum model,power law wind profile model,then generate turbulent wind field through TurbSim and generate seismic acceleration response spectrum based on GB50011-2010.Combining TurbSim,AeroDyn,FAST and Seismic to simulate the dynamic characteristics of the wind turbine structure under different wind loads and different earthquakes.2.The dynamic response of the wind turbine tower structure under different seismic wave is studied.It is found that the seismic shear wave has a great influence on the wind turbine structural response.The seismic longitudinal wave has little influence on the wind turbine structure response,so the longitudinal wave is negligible.The horizontal direction structure response is much larger than the vertical response,and the vertical response of the earthquake to the wind turbine structure is negligible.At the same time,it is found that the wind load has a great influence on the wind turbine blade,and the earthquake has little influence on it.The impact of the earthquake on the flow direction displacement and lateral bending moment of the tower is equivalent to the aerodynamic load,and the influence on the lateral displacement and the flow direction bending moment of the tower is greater than that of the aerodynamic load.3.Based on GB50011-2010,seismic acceleration response spectra of different seismic intensities and soils of different sites are generated,in order to study the seismic dynamic response of wind turbine structures under different sites.The analysis results show that under the same seismic load,in sites I,II,III and IV,the structural response is gradually increased.In the IV site,the tower-top displacement of the wind turbine,the acceleration of the nacelle,the acceleration of the platform and the bending moment of the tower are the largest,that is,the softer the soil of the site,the more severe the structural response,and the greater the bending moment.With the increase of seismic intensity and the enlargement of wind turbines,the difference in structural response of different sites is greater,and the curve of bending moment varies with tower height tends to be linear.4.Based on ABAQUS,the model of tower,foundation and soil were established,and the modal analysis,stability analysis and dynamic analysis of the tower were carried out.The analysis results show that the main motion forms of the tower are rocking motion and bending vibration;the first-order natural frequency of the tower is 0.290 Hz,which is greater than the rated rotational frequency of the wheel of 0.202 Hz.Therefore,the rotation of the blades does not cause the wind turbine tower to resonate.The buckling form,buckling position and buckling factor of the tower under different loads are different: under the action of wind load,the tower undergoes lateral buckling,and the buckling position is located at the bottom of the tower and gradually develops toward the middle of the tower with increasing order,and the buckling factor is higher;under the action of seismic load,the tower undergoes longitudinal buckling,and the bucking position is similar to that of the wind load,but the area is relatively larger and the buckling factor is relatively small.Significant stress concentration occurs at the contact between the base platform and the soil.