Study On Dynamic Characteristics And Power Performance Of Wind Turbine Considering Wind-structure-soil Interaction

In today’s world,vigorously developing wind power industry based on wind turbine can not only realize ecological protection,but also solve the problem of energy shortage.Under the excitation of external load,the vibration modes of the wind turbine’s rotor,engine room and tower are coupled with each other.At this time,changing the operating state,environmental effects and pitch angle will cause changes in the structural dynamic characteristics and wind power perfor mance,which will affect structural safety and power generation capacity of the wind turbine.Therefore,the wind tunnel scale test was carried out systematically to study the influence of various factors on the structural dynamic characteristics and power performance of wind turbine.The main research contents are as follows:According to the scale criterion and dimensional analysis theory,the scale model of wind turbine was established.Firstly,considering all kinds of excitation of the structure,the analysis of dynamic characteristics and power performance was systematically carried out.Secondly,taking the NREL-5MW wind turbine as the prototype,considering all kinds of influencing factors,the scale criteria of the model wind turbine was given,and two scale test models of rigid foundation and single pile foundation was designed and made,which can reflect the actual situation of the prototype.Thirdly,the wind-structure-soil synchronous test platform was built in the wind tunnel laboratory by integrating the wind turbine scale model and the dynamic signal acquisition test system,which provides realistic conditions for the subsequent test.Based on the synchronous test platform,the influence of wind power characteristics was studied.Taking the established wind turbine model as the research object,the fundamental frequency verification test was carried out,and the results show that the model can satisfy the design requirements and reflect the actual situation of the prototype.Based on this model,the follow-up tests were carried out.Firstly,the influence of operation state on the natural frequency of wind turbine was studied.The results show that the fundamental frequency increases when the wind turbine rotates.Secondly,taking the rotating wind turbine as the research object,the influence of foundation form on dynamic characteristics and response was studied.The results show that neglecting the pile-soil interaction will not only overestimate the fundamental frequency but also underestimate the damping ratio and dynamic response.Thirdly,taking the rotating monopile supported wind turbine as the research object,setting the condition of equidistant variable pitc h angle to study its influence on the damping ratio and dynamic response.The results show that the forward variable pitch angle can reduce the thrust and realize the structural load reduction,which is beneficial to increase the damping ratio and reduce t he dynamic response of the system.The wind power performance of monopile supported wind turbine in rotating state was studied.Firstly,the aerodynamic performance of wind turbine with different scale schemes was studied.The test results show that the aerodynamic similar wind turbine can better reflect the prototype situation than the geometric similar wind turbine.Secondly,taking the aerodynamic similar wind turbine model as the research object,the equal pitch angle hub was designed and manufactured to systematically study the influence of wind speed and pitch angle on torque and power.The results show that the torque and power increase with the increase of wind speed,and the change of pitch angle has a significant effect on the torque and power.Thirdly,by using the new power coefficient curve determination method,the test curve was obtained to study the influence of pitch angle on torque coefficient which under variable wind speed and power coefficient which under variable tip speed ratio.The results show that the appropriate change of pitch angle according to the real-time wind speed is conducive to the power control of wind turbine and the operation safety of power grid,which can provide a reference for stable power generation.