水平轴风电机组风轮系统动态载荷特性研究

发布时间：2018-03-17 20:10

本文选题：风电机组　切入点：风轮系统　出处：《华北电力大学》2014年硕士论文　论文类型：学位论文

【摘要】：风轮系统作为风电机组最核心的部件之一,研究其在实际运行过程中的动态载荷变化特性以及气弹耦合过程特性是进行风电机组设计与优化,确保机组运行寿命及整体安全稳定的重要理论基础。以Beddoes-Leishman动态失速简化模型为基础,通过Matlab编程仿真分析了NACA0012翼型的动态失速特性。结果表明在翼型静态失速攻角变化范围内,翼型的失速攻角发生了明显延迟,动态升力系数较静态升力系数出现了明显的增加,而翼型动态阻力系数较静态阻力系数则变化不大。在研究模型参数对翼型动态失速特性的影响方面,结果表明当翼型平均攻角运行范围处于轻度失速和深度失速区时,翼型的动态失速效果明显；增加衰减频率可抑制流动分离的发生；增加压力时间常数可以提高最大升力系数,而增加边界层滞后时间常数可以提高动态失速攻角。在经典叶素动量理论及相关修正基础上,引入Pitt-Pitters和TUDk动态入流非定常模型,编写基于这两种模型的刚性风轮系统动态载荷仿真计算Matlab程序,在对阵风等风速快速变化工况下的仿真结果表明：TUDk动态入流模型与GL GH Bladed计算的诱导速度和风轮系统载荷结果基本一致,证明了编写的计算程序的有效性；在对动态瞬间变桨工况下的仿真结果表明Pitt-Pitters模型和TUDk模型与不考虑动态入流效应的均衡尾涡模型相比均能够真实反映风轮系统载荷的过冲击现象。在引入动态入流模型基础上,将翼型动态失速模型加入到风轮系统载荷仿真计算程序中,仿真分析了在湍流风工况下的风轮动态载荷变化特性,结果表明局部叶素气动载荷与风轮系统整体载荷都较不考虑动态失速时的载荷有明显的增加。利用梁的动态变形原理推导考虑与不考虑叶片离心刚化效应时的柔性风轮系统叶片结构动力学方程,对局部叶素气动外阻尼的计算方法进行研究推导,编写了叶素气动外阻尼Matlab仿真计算程序,对模型叶素仿真结果表明叶素面内较面外方向更容易出现负阻尼。将动量叶素理论与结构动力学模态叠加法相结合,编写了考虑气弹耦合过程的风轮系统载荷Matlab仿真计算程序,通过对叶片模态阻尼随桨矩角变化特性的仿真结果表明模型中的叶片在正常运行范围内是气弹稳定的；在湍流风仿真工况下,编程仿真与GL GH Bladed计算的载荷与叶尖变形结果都具有较好一致性,证明了气弹耦合仿真计算结果的合理性。
[Abstract]:As one of the most important components of wind turbine, wind turbine system is designed and optimized to study the dynamic load variation characteristics and aero-elastic coupling process characteristics of wind turbine unit in actual operation. The important theoretical basis to ensure the operation life and overall safety and stability of the unit. Based on the simplified dynamic stall model of Beddoes-Leishman, the dynamic stall characteristics of NACA0012 airfoil are simulated by Matlab. The results show that the stall angle of airfoil is obviously delayed in the range of static stall angle of attack. The dynamic lift coefficient is obviously increased than that of the static lift coefficient, but the dynamic drag coefficient of airfoil is not much different from that of static resistance coefficient. In the aspect of studying the influence of model parameters on the dynamic stall characteristics of airfoil, the dynamic drag coefficient of airfoil is less than that of static drag coefficient. The results show that when the mean angle of attack of airfoil is in the range of slight stall and deep stall, the dynamic stall effect of airfoil is obvious, the increase of attenuation frequency can inhibit the occurrence of flow separation, and the increase of pressure time constant can increase the maximum lift coefficient. Increasing the lag time constant of the boundary layer can increase the angle of attack of dynamic stall. On the basis of the classical momentum theory of blade element and the related correction, the Pitt-Pitters and TUDk dynamic inflow unsteady models are introduced, and the Matlab program for the dynamic load simulation of rigid wind turbine system based on these two models is compiled. The simulation results under the condition of fast variation of gust and constant wind speed show that the induced velocity and the load of wind turbine system calculated by GL GH Bladed are basically the same as those of the 1: TUDK dynamic inflow model, which proves the validity of the calculation program. The simulation results under the dynamic transient variable propeller condition show that the Pitt-Pitters model and the TUDk model can truly reflect the overshock phenomenon of the wind wheel system load compared with the equilibrium wake model which does not take into account the dynamic inflow effect. The dynamic stall model of airfoil is added to the load simulation program of wind turbine system, and the dynamic load variation characteristics of wind turbine under turbulent wind condition are simulated and analyzed. The results show that the aerodynamic load of local blade element and the whole load of wind turbine system are obviously increased when the dynamic stall is not considered. Based on the dynamic deformation principle of beam, the dynamic equations of blade structure of flexible wind turbine system considering and without centrifugal stiffening effect of blade are derived, and the calculation method of aerodynamic external damping of local blade element is studied and deduced. A Matlab simulation program for aerodynamic external damping of leaf element is developed. The simulation results of the model leaf element show that the negative damping is more likely to occur in the leaf element plane than in the off-plane direction. The momentum leaf element theory is combined with the structural dynamic modal superposition method. The Matlab simulation program of wind turbine system load considering the Aeroelastic coupling process is compiled. The simulation results of the blade modal damping with the pitch angle show that the blade in the model is Aeroelastic stable in the normal operation range. Under the condition of turbulent wind simulation, the load calculated by programming simulation is in good agreement with the result of blade tip deformation calculated by GL GH Bladed, which proves the rationality of the results of Aeroelastic coupling simulation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614

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