考虑叶片旋转及土-结构相互作用对风电结构动力特性影响的研究

风力发电建设场地土特性及叶片转速变化会引起风力发电机动力特性及响应发生变化。基于西北地区某风电场的2 MW三桨叶水平轴风力发电机,利用ANSYS软件建立风力发电机整机模型,考虑叶片旋转及土-结构相互作用对风力发电机动力特性的影响,研究风力发电机在不同叶片转速、不同场地条件及两者共同作用下的动力特性变化规律,并利用坎贝尔图分析上述工况下风力发电机的共振特性。结果表明:叶片转速增加使风力发电机的自振频率逐渐增大,塔筒与叶片的耦合变形使频率增长加快;考虑土-结构相互作用时,风力发电机频率降低,且场地土越软风力发电机频率越小;当两种工况共同作用时,叶片旋转只对一阶频率产生影响,对高阶频率影响甚微,且风力发电机频率降低;考虑叶片旋转时风力发电机在1P转频内不产生共振点,在3P转频内一阶频率的共振点为14 r/min。此外在不同场地土下风力发电机均会产生共振点,其中Ⅲ类土的共振频率最远离额定转频。因此在风电场的场地选择、结构设计及日常运行时应注意其动力特性变化,使其频率远离共振区域,为风力发电机安全运行提供保障。

INFLUENCE OF BLADE ROTATION AND SOIL-STRUCTURE INTERACTION ON DYNAMIC CHARACTERISTICS OF WIND POWER STRUCTURE

The dynamic characteristics and response of wind turbines can be changed by the variation of soil characteristics and rotational velocity of blades. Based on the 2 MW three-blade horizontal axis wind turbines in Northwest wind farm,the model of wind turbine is established by using ANSYS software,considering the influence of blade rotation and soil-structure interaction on the dynamic characteristics of wind turbine,the wind turbine is studied in different working conditions(different blade rotational speed,different site conditions and both),and uses Campbell diagram to analyze the resonant characteristics of wind turbines under these conditions.The results show that the vibration frequency of wind turbines increases with the increase of blade speed,the coupling deformation of the cylinder and the blade increases the frequency;Considering the soil-structure interaction,the frequency of the wind turbine is reduced and the frequency of the soft wind generator is smaller. When the two working conditions work together,the blade rotation only affects the first order frequency,it has little effect on high order frequency,and the frequency of wind turbine is lower,considering that the wind turbine does not produce resonance point in 1 P rotating frequency,the resonant point of the first order frequency in 3 P rotating frequency is 14 r·min-1. In addition,the resonant points of wind turbines are generated in different sites,and the resonant frequencies of three kinds of soils are far away from the rated frequency. Therefore,in the field selection,structure design and daily operation of Wind farm,it is necessary to pay attention to its dynamic characteristic change,so that its frequency is far away from the resonant region and provide guarantee for the safe operation of wind turbines.