| As a typical high-rise structure,wind turbine is established in complex environment and comfort is not considered.So structure vibration is significant,and it is very important to study the reliability of wind turbine subjected to the environmental loads.In this study,the damage assessment of wind turbine under different environment loads is taken as the research background.Through theoretical analysis,numerical simulation and shaking table test,the researches on the influence of non-Gaussian characteristics of wind loads on extreme and fatigue reliability of wind turbine and the evaluation of seismic performance of structures under near-and far-field ground motions are carried out.The main research contents and results are as follows.(1)Based on the real wind field data by the masts,non-Gaussian characteristics of wind field are analyzed.According to the translation models,three types of wind fields,namely Gaussian,hardening non-Gaussian and softening non-Gaussian processes,are generated by Kaimal spectrum.And the influences of non-Gaussian characteristics of wind loads on dynamic response and extreme value reliability of the control section of wind turbine are discussed.The dynamic response is calculated by the aerodynamic model of blade and the multi-body dynamics,and the time-domain and frequency-domain characteristics of the response are analyzed.The short-term extreme response of dynamic response with different wind speed ranges under operational and parked condition is analyzed by ACER method.The failure probability of the control section with different return periods are obtained by combining with the probability density function of the average wind speed.The results show that the means of the first three statistical moments of dynamic response and bandwidth coefficients under three types of wind fields are approximately the same.The non-Gaussian characteristics have a great influence on extreme responses with 10-,20-and 50-year return periods.Probabilities of the first-passage failure with different service lives vary significantly.The non-Gaussian characteristics should be considered in the extreme reliability analysis.(2)When the dynamic responses are obtained,the crack initiation life and crack propagation life of the control section under three types of wind fields are discussed in detail using linear damage accumulation theory and linear crack propagation theory respectively.And the influences of the uncertainties of the load and material on the fatigue life of structures are considered.The results show that the influence of the non-Gaussian characteristics on the fatigue life becomes significant with the increase of the annual mean wind speed.Therefore,for areas with higher annual mean wind speeds,the influence of non-Gaussian characteristics on the crack initiation life should be considered.(3)The influence of the non-Gaussian characteristics of wind loads on the fatigue life of the control section of wind turbine are discussed with consideration of the joint probability density distribution of the wind direction and mean wind speed.The accuracy and applicability of the Offset Elliptical Normal model for the joint PDF of wind speed and direction are verified based on the measured data of wind speed.Then the wind direction is divided into 16 wind angles and the mean wind speed is simplified to the Weibull distribution.The parameters of the Weibull distribution are calculated by the Power Density method.Based on that,the joint PDF of wind speed and direction are derived.And the influences of the non-Gaussian characteristics on crack initiation and crack propagation lives are evaluated with combination with the measured data in the area of the project.The results show that the crack initiation and crack propagation lives of the control section are the smallest under the softening wind loads.The control point is in the dominant wind direction of the area of the project.(4)A shaking table test is carried out based on an offshore wind turbine.The influence of the ordinary ground motions,the near-field and far-field long-period ground motions on the dynamic response of wind turbine is estimated by the test.The results show that the peak value of the displacement of the top of wind turbine shows an approximate linear increase with the increase of the PGA under different types of ground motions.Compared with the ordinary ground motions,the near-field and far-field long-period ground motions have a greater influence on the dynamic response.The displacement is larger under long-period ground motions,especially for the far-field long-period ground motion which is more adverse to the structure and controls the limit state of elasticity and plasticity of wind turbine.And the long-period ground motions play the dominant for the seismic performance evaluation.(5)The influence of the spatial distribution characteristics of the near-fault ground motion on the dynamic response of wind turbine are estimated by taking the 1999 Chi-Chi earthquake in Taiwan as the research object.According to the relative space position of the station and fault,the near-field ground motions are divided into the Forward District,Backward District and Middle District.The frequency characteristics of three types of ground motions are analyzed and the influence of different ground motions on the SDOF system is assessed.Based on that,the seismic response is analyzed with consideration of the spatial distribution characteristics of ground motions.Then the correlation between the parameters of ground motions and the dynamic response are calculated.The results show that it has a correlation between the parameters of the near-fault ground motion and the dynamic response.Considering the spatial distribution characteristics,the input energy and PGV have significant influence on the dynamic response for both the Forward District and Middle District.But the dynamic response has high correlation with the PGA and input energy for the Backward District.In the design of wind turbine,the control parameters of the input ground motion should be selected properly according to the area of the project. |
PDF Full Text Request