| After the sustainable development strategy was put forward,social attention to new energy has been significantly enhanced.In this context,with the wind power generation technology increasingly towards the trend of large blades,high power and high tower,the overall reliability of the tower structure of the fan has become increasingly prominent.In the process of operation,the tower structure will be affected by the wind load pulsation effect,which will cause the corresponding negative effect,resulting in vibration.Offshore fan is also in a complex Marine environment,under the action of a variety of loads,and has a relatively prominent periodicity.Under the action of long-term cyclic load,fatigue damage is easy to occur,especially under the influence of strong wind and waves,which will lead to vibration of the structure and adversely affect the stability of the structure.Therefore,the requirement of fan fatigue resistance design is higher.Taking fatigue damage as the control target,this paper adopts TMD commonly used in engineering to control the vibration of fan tower under the action of wind and waves,so as to meet the requirement of fan durability.In the process of the development of computer technology,the performance of the fan can be studied by means of numerical simulation.Taking a 3 MW fan of an offshore wind farm as an engineering example,based on the vibration reduction principle of TMD,through the parameter optimization design method with structural fatigue reliability as the control index,the parameters of the TMD system are rationally optimized,and then the best parameters can be determined to achieve effective vibration control.The research work of this paper mainly covers the following contents,namely:(1)Firstly,the structure of the fan is properly simplified,and the three-dimensional model of tower,blade and foundation is established with the finite element software ABAQUS.It is close to the actual structure,and then carries on the modal analysis to the fan to understand the structure’s natural vibration characteristics.At the same time,it checks whether the natural vibration frequency of the fan avoids the resonance frequency,that is,whether it meets the requirements of safety.(2)The stochastic process of wind speed fluctuation is expressed as a finite sum of the deterministic time function and the corresponding uncorrelated random coefficients by orthogonal extension method.The time history of wind and wave loads is described in the form of spectrum of stochastic processes.The analysis of this aspect is realized by means of MATLAB programming..(3)the fan model of discrete model for multiple degree of freedom system,established the coupled equations of motion,through MATLAB with material mechanics fan at the bottom of the tower drum stress calculation formula for calculating stress time history,according to the calculated point tower drum stress time history,use of MATLAB programming of rain flow count method,calculates the stress time history points into a series of discrete stress cycle,and based on the s-n curve and Miner linear cumulative damage theory,the fatigue life of tower drum calculation points.(4)According to the probability density evolution theory,the overall system equation of TMD structure is established,the TMD parameter optimization design method based on reliability is given,the influence of tuning TMD parameters on the vibration reduction effect is found out,and the optimal control parameters of tuned mass damper are found.The optimal vibration reduction parameters are obtained to reduce the vibration of the fan tower,so as to extend the fatigue life of the wind turbine. |
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