| Wind power industry is developing rapidly as a kind of rich and clean renewable energy.The tower is an important bearing component of wind turbines,and its performance directly affects the stable operation of wind turbines.With the increasing capacity of wind turbines,the faults of wind turbine tower in strength,vibration,stability and fatigue life become prominent.Therefore,based on the National Natural Science Foundation of China and the IEC & GB certification standards,combined with the finite element simulation test,uniform design method and multi-objective optimization algorithm,the MW tower structure prototype was optimized.The optimization design of wind turbine tower can promote by this research.The specific content and the obtained research conclusions are as follows:(1)Analysis of load,static,dynamic and stable characteristics of tower.Firstly,the finite element model of the tower conbined with door hole and flange was established,and the mechanical model of the tower was loaded.The loads of the tower under extreme wind speed conditions were calculated.Secondly,utilised structural mechanics,elastic mechanics,fatigue cumulative damage,etc.,the static strength,free vibration characteristics,stability and fatigue life of the tower were verified through the finite element software.The static strength and stiffness of the tower meet the design requirements under extreme conditions.The first-order natural frequency value of the tower is 0.34488 Hz.From the Campbell diagram,it shows that the low-order natural frequency of the tower completely avoids the 1P and 3P operating frequencies of the wind turbine rotor,i.e.the resonating of tower does not occur.Based on the nonlinear buckling theory,the buckling safety factor of the tower was calculated to be 0.06,which is smaller than the IEC requirement,viz.the tower is stable.According to the Miner criterion,the minimum fatigue life of tower is 4.1797E7 cycles,and its cumulative fatigue damage less than 1,indicating that the tower can satisfy the design life of 20 years.(2)Establishing numerical simulation tests of tower structural parameters based on uniform design method.The thickness and height of the fourth section location ten of the tower are selected as design variables.The finite element simulation experiments were arranged by the U9*(92)uniform design.According to the test results,the fitting mathematical models between the five structural characteristics(maximum equivalent stress,maximum displacement,first-order natural frequency,first-order critical buckling load and fatigue life)and the structural parameters were obtained.(3)Multi-objective optimization in structural parameters of wind turbine tower.Firstly,combining the numerical simulation test results to give the optimization objective functions,setting the relevant algorithm parameters,the 12 sets of nondominated solutions were calculated.Secondly,with the frontier region of nondominated solution depicted,the characteristics of non-dominated solutions were compared,it was found that the thickness variable has great influence on the optimization target,and the contradictory trend between the weight and the fatigue life target had been described.Finally,by comparing 3 sets of optimization schemes,the recommendations based on design preferences were supplied,and the optimal solutions for conservative design were given.The multi-objective optimization of wind turbine tower structure parameters can improve by this project. |
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