多工况下大型风力机动态响应研究

Research on Dynamic Response of Large-Scale Wind Turbine Under Multiple Loading Conditions

开机启动、偏航运动以及紧急停机等多种非稳定工况下,大型风力机长柔叶片及高柔塔架气弹响应呈现强非线性,结构动力学时频域响应非平稳特征明显。为研究风力机非稳定工况的动态响应,本文基于NWTCUP湍流风谱模型和Kelvin_Helmholtz Billow(KHB)建立了平均风速不同的风力机运行风场环境,通过开源软件FAST计算了NREL 5 MW风力机在非稳定工况下的动力学响应,并使用HHT方法对响应结果进行时频域分析,提取了叶片及塔架振动特征频率,结果表明:在塔架一阶固有频率及风轮旋转频率的响应为非平稳过程,偏航及紧急停机等系统传动载荷动态变化的非稳定工况尤为明显,紧急停机导致的负气动阻尼对叶尖位移的影响为具有混沌特征的非线性扰动,叶片铺层设计时应考虑适当增大结构阻尼以改善这一现象。

The aero-elastic responses of wind turbine flexible blade and tower are nonlinear on start-up,yawing motion and emergency shutdown conditions.The structure dynamic behaviour in time-frequency domain is non-stationaryobviously.This paper create turbulence wind field based on NWTCUP turbulent spectrum and Kelvin-Helmholtz Billow（KHB） to predict the wind turbine dynamic behaviourunder non-stationary conditions.The open source code FAST is employed to obtain the dynamic responses of NREL 5 MW wind turbine on a condition which has combined start-up,normal operating,yawing and emergency shutdown processes.The HHT method is applied for time-frequency domain analysis to extract the characteristic vibration frequency.The results show that responses of rotor rotation frequency and first-order natural frequency of tower are nonstationary process.It＇s more obviously on yawing and emergency shutdown conditions.The effect of negative aerodynamic damping caused by emergency shutdown on blade-tip deflection has a chaotic characteristic.Enlarging the structural damping should be considered in the initial lay-up design of blade to perfect the situation.