基于机电惯容的漂浮式海上风力机无源振动控制

机电惯容是一种新型惯容装置,可利用电路网络实现高阶机械阻抗,具有性能和空间上的优势。由于海上风力机的机舱空间有限,研究了位于浮式平台中的机电惯容系统对漂浮式海上风力机载荷的影响。根据直流电机的特性,电机轴的转矩输出与电机回路中的电流呈线性关系,因此针对所建立的机电惯容,重点研究了所有由单个电阻、电容、电感组成的电路网络对漂浮式风力机减振性能的影响。为了降低优化过程中的复杂度,首先建立了3自由度(Degree of freedom,DOF)漂浮式海上风力机模型,随后优化了含有电路网络模型的输入输出传递函数的H2范数,得到电路网络最优参数。最后,基于美国可再生能源实验室的5 MW基准风力机模型对优化结果进行了仿真分析。仿真结果表明,在不考虑装置工作行程的情况下,所建立的机电惯容调谐质量阻尼器(Mechatronic inerter tuned mass damper,MITMD)系统可以有效减少风力机系统的结构载荷。相较于减振装置位于机舱中的情况,建立在平台中的MITMD系统可以同时减轻塔基和塔顶转轴处的载荷。MITMD的控制效果以运动位移为代价,因此在实际应用中需要折中考虑减振效果和装置...     

Laboratory-scale experiments on wind turbine nacelle movement estimation

The effect of nacelle motion should be considered when calculating the wind speed relative to the wind turbine structure, which is essential in wind turbine control and performance testing. A Kalman filter approach is applied to estimate the nacelle motion of a wind turbine. Information from several accelerometers and strain gauges which are installed on the wind turbine tower is combined with the Kalman filter. An optimization algorithm is used to choose the optimal locations for strain gauge and accelerometer installation. A laboratory-scale experimental rig which mimics the tower and nacelle of the wind turbine is constructed to evaluate the performance of the proposed estimator algorithm. The usefulness of the proposed algorithm is validated by these laboratory-scale experimental results.     

基于多岛遗传算法的漂浮式风力机稳定性多重调谐质量阻尼器优化控制

将多重调谐质量阻尼器（MTMD）引入漂浮式风力机控制领域以提高漂浮式风力机的稳定性。以NREL 5MW风力机及ITI Barge平台为研究对象,提出在漂浮式风力机机舱和塔架中配置2个参数不同的调谐质量阻尼器（TMD）,并基于多岛遗传算法,算出MTMD系统最优参数。通过对3种典型工况下、有无配置MTMD的漂浮式风力机进行模拟计算,研究了最优MTMD的控制效果。结果表明：多岛遗传算法能够有效优化MTMD参数;MTMD控制优于单一TMD控制;经参数优化后,MTMD对漂浮式风力机振动的控制效果更好,塔顶纵向位移和平台横摇角标准差抑制率分别提升了80.4%和83.8%;MTMD对漂浮式风力机不同部位的控制效果不同,控制效果最好的为塔顶纵向位移、塔根横向弯矩及平台横摇角;不同环境工况下,MTMD对漂浮式风力机都有着明显的控制效果,其中纵向载荷和位移的标准差抑制率分别为10.3%~12.1%和76.1%~78.3%,横向载荷和位移的标准差抑制率分别为75%~77.7%和8.9%~10.8%。     

考虑土－结构相互作用的风力发电高塔系统地震动力响应分析

研究考虑土－结构相互作用(Soil-structure interaction, SSI)的风力发电高塔系统地震动力响应分析问题。建立风力发电高塔系统“桨叶－机舱－塔体－基础”一体化的多体系统动力学有限元模型。基于多体系统动力学基本原理,风力发电高塔系统被离散为一系列连续的超级单元,而风力发电高塔系统土－结构相互作用则可通过在基础和土体交界面上设置弹簧和阻尼器来实现。在多体系统动力学方法中,可根据材料力学确定难于确定的超级单元参数和依据Lagrange法推导多体动力学控制运动方程。为了研究风力发电高塔系统的动力特性,基于欧洲规范(Eurocode8)对风力发电高塔系统进行了地震作用动力时程分析。研究表明,考虑SSI效应与否对结果影响较大。一般来说,考虑SSI效应会增加塔体基础与地基连接的柔度。同时,SSI效应在不同自由振动中所起的作用不一样,它对弯曲振动尤其是高阶弯曲振动的影响比较大。因此,在对风力发电高塔系统进行地震动力响应分析时,应该考虑SSI效应。     

Numerical analysis of the spatial distribution of equivalent wind speeds in large-scale wind turbines

The effects of wind shear and the tower shadow contribute to periodic fluctuations in the wind speed and aerodynamic torque, which cause several problems. This study develops an equivalent wind speed model for large-scale, n-bladed wind turbines that includes the wind shear and the tower shadow effects. The comprehensive model is used to derive the disturbance components of wind speed caused by wind shear, the tower shadow, their synthesis, and the equivalent wind speed and to delineate their spatial distributions in the rotor disk area. Simulation results reveal that the effects of wind shear, the tower shadow, and the equivalent wind speed on the disturbance components fluctuate periodically and are closely related to the wind turbine correlation parameters, such as the rotor radius, hub center height, tower radius, distance from the tower midline to the blade, wind shear exponent, and blade number.

     

Load and dynamic characteristic analysis of wind turbine flexible blades

Aiming at the Megawatt (MW) scale wind turbine, a dynamic analysis and simulation method is presented to research blade loads and dynamic characteristics. To consider blade flexible deformation, the whole blade was divided into a number of units. Each unit was treated as a rigid body, the flexible connection between two adjacent units is considered. A nacelle coordinate system, a rotating shaft coordinate system, and a blade coordinate system were employed to describe the wind turbine blade. In those coordinate systems, blade inertial load calculation model, centrifugal force load calculation model and gravity load calculation model are established. Combining load model with the whole model of wind turbines, the real-time dynamic simulation model of blade loads was established in Simulink circumstance and a numerical simulation was performed. Based on the simulation analysis, some research results were obtained. When the large instantaneous fluctuation of electromagnetic torque of generator happens, rotor speed does not appear to have large fluctuation due to the inertia of the wind rotor, but the blade vibration speed changes obviously. Gravity has a periodic variation in the process of blade rotation and has a large influence on the edgewise moment. The research results provide a helpful reference for the structure design, operation, and control of wind turbines.     

风电叶片三维参数建模及振动分析

利用目前风力机叶片设计普遍采用的优化设计方法Wilson设计方法,通过MATLAB编程,开发了小型叶片气动设计的应用程序,并利用该程序设计了一台3kW小型水平轴风力机叶片.采用MATLAB和ANSYS共同建立了风力机叶片三维有限元参数模型,MATLAB编制的建模程序提高了初期设计效率,缩短了ANSYS分析前处理时间.在此基础上进行了叶片固有振动特性计算,分析了叶片的振动特性及其与结构参数之间的关系,分析方法和结果对风电叶片的结构设计和动力分析有一定的参考价值.     

Aerodynamic response analysis of wind turbines

Wind energy has received increasing attention in the same way as energy crisis and environmental deterioration. The aerodynamic response of wind turbines is the major problem in wind turbine design. Blade element momentum theory was used to study the aerodynamic thrusts of the blades on the tower. Iterative solutions were used to calculate the axial flow induction factor for each cross-section of the blades. The harmonic superposition method was used to simulate the fluctuating wind velocity time histories. The wind shear equation was used to calculate the mean wind velocities at different heights. Finally, the finite element method model was used to study the aerodynamic response of wind turbines under random wind loads. Results show that the top displacement of tower is increased accordingly by increasing the rotational speed of the blades. Hence, this should be considered in wind turbine design.     

大型风力机塔架的模态与强度分析

针对大型风力机运行中塔架常见的倾斜、中间凸出、焊缝开裂等故障,利用ANSYS有限元分析软件和工程算法对其结构进行了动力特性、屈曲分析和焊缝的分析。通过塔架模态分析可以优化塔架设计,避免风机在正常工作时塔架与风轮发生共振;屈曲和焊缝分析能够保证塔架的刚度和强度满足极限工况的负荷要求,从而为塔架的结构设计提供最佳参数依据。     

风力机气动力不对称故障建模与仿真

风力机气动力不对称故障对风力发电机组的安全稳定运行有很大的影响,传统的基于振动的故障诊断方法需要在风力机上安装大量的传感器,成本较高,可靠性也较差。近年来,已有学者采用基于电信号的故障诊断方法对该故障进行了实验研究,但未对该诊断方法进行理论上解释。笔者研究了气动力不对称故障下的风力机的塔架振动和气动力的耦合规律,阐述了造成电功率波动的机理,指出电功率的波动来源于塔架的振动,建立了整个风力机组故障状态下的模型,仿真得到了故障条件下的塔架振动信号与电功率信号,对仿真得到的振动信号与电信号进行信号处理。结果显示其中均出现了叶轮旋转的一倍频分量,与德国ISET等实验研究的结果相符,对开发新的故障诊断算法具有重要意义。     

大型风力机叶片研究现状与发展趋势

叶片是风力机最为关键的部件之一,叶片、轮毂组成的风轮是能量捕获机构,将风能转变为机械能,与此同时,叶片又是风力机力源,主要承载部件,对整个风力机安全运行起着关键作用。在对大型风力机及其叶片产业发展现状分析基础上,从气动外形与结构设计现状、运行监测与控制技术现状、发展趋势与有待研究的问题等几个角度进行较为全面的梳理总结,从而从总体上把握现代大型风力机叶片研究现状及发展趋势。指出今后将在针对抗台风叶片、低风速叶片、仿生叶片和低噪音叶片等的个性化设计,具有外部载荷环境和自身结构状态变化感知功能的智能风力机叶片设计等方面进一步发展;已经形成的风力机叶片设计、制造及运行监控理论等还要随着大批量风力机全生命周期服役实践,进一步完善和发展。     

风电行星齿轮系统变载荷激励动力学模型及其响应特性

针对风电行星齿轮系统变载变速的运行特点,通过分析系统构件为刚体和弹性体时的受力情况,应用运动合成原理,提出了变载荷激励下行星齿轮系统动力学模型的建立方法,并推导出系统的运动微分方程。在此基础上,分析了行星齿轮系统的内外部激励因素及其对系统动载荷和动载系数的影响机理。计算并分析了某MW级风电行星齿轮系统的动态响应,结果表明：系统的时变啮合刚度和时变轴承刚度主要影响响应频率的数值大小和系统的振动能量;外部变载荷使响应频率中存在明显的低频成分,并影响各阶振动间的能量分配;齿轮啮合力的动载系数主要受到外部变载荷的影响,而轴承力的动载系数同时受到系统内部激励和外部激励的影响。研究结果为风电齿轮箱的疲劳寿命分析和动态优化设计奠定了基础。     

The inception of OMA in the development of modal testing technology for wind turbines

Wind turbines are immense, flexible structures with aerodynamic forces acting on the rotating blades at harmonics of the turbine rotational frequency. These harmonics are comparable to the modal frequencies of the structure. Predicting and experimentally measuring the modal frequencies of wind turbines have been important to their successful design and operation. Performing modal tests on wind turbine structures over 100 m tall is a substantial challenge, which has inspired innovative developments in modal test technology. For wind turbines, a further complication is that the modal frequencies are dependent on the turbine rotation speed. The history and development of a new technique for acquiring the modal parameters using output-only response data, called the Natural Excitation Technique (NExT), will be reviewed, showing historical tests and techniques. The initial attempts at output-only modal testing began in the late 1980s with the development of NExT in the 1990s. NExT was a predecessor to Operational Modal Analysis (OMA), developed to overcome these challenges of testing immense structures excited with natural environmental inputs. We will trace the difficulties and successes of wind turbine modal testing from 1982 to the present.     

Output-only modal analysis of wind turbine tower based on vibration response under emergency stop

The identification technique of output-only modal parameters is proposed for the large wind turbine tower under emergency stop. Compared with the response of regular operating conditions, the immediate tower structural response under emergency stop much more resembles a state of free vibration, which is more appropriate for the modal identification of the wind turbine tower. The vibration response is measured in the nacelle, which is easy to perform in the field modal test. The variational mode decomposition (VMD) is applied to decompose the vibration response into several band-limited intrinsic mode functions. The free responses of decomposed functions are extracted by applying the random decrement technique (RDT). Finally, the modal damping ratio and natural frequency are identified from each free modal response by using the Hilbert transform method. Simulations and a 1.5 MW wind turbine field modal test results verify the effectiveness of the proposed identification method. The main modal parameters of wind turbine, including weak modes, are effectively extracted by using output-only vibration responses under emergency stop. The modal parameter identification method is provided for the large wind turbine structure under the engineering condition.     

适应于多种类型风力发电机的在线监测系统的开发

风力发电机由于其恶劣的工作环境以及其复杂多变的工况,在运行时经常出现故障,导致停机维修,造成了很大的经济损失。而当前已经有开发了一些在线监测系统,大多是只针对一种形式结构的风力发电机,而往往风场中会存在多种类型的风机：如双馈式的、直驱式的、还有半直驱式的,而每种风机的内部结构存在着很大的差别,各有优异。针对当前的实际情况,开发了一套针对多种类型的风力机在线监测系统。系统在数据库设计、参数设置、监测界面都融合了多种形式的风力发电机,在自制的模拟风力发电机的台架上试运行已经取得了理想的效果。     

Aerodynamic shape optimization of wind turbine rotor blades considering aeroelastic deformation effect

An aerodynamic shape optimization framework of two modules is developed for improving the aerodynamic performance of wind turbine rotor blades. The first module conducts CFD-based aeroelastic analysis for the complete blade configuration to evaluate the turbine performance and to extract the sectional flow conditions at selected blade sections. The second module performs 2-D shape optimization of blade sections to maximize the lift-to-drag ratio under given sectional flow conditions. When the optimization is completed for all selected blade sections, the performance and sectional flow characteristics of the new blade reconfigured from the optimized sections are evaluated again by the CFD-based aeroelastic analysis. The above procedure is repeated until the solution converges satisfactorily. Applications were made for the NREL phase VI and the NREL 5MW reference wind turbines. The results showed that the optimization framework can be effectively utilized in enhancing the aerodynamic performance of wind turbine blades.

     

Output-only modal analysis of linear time-periodic systems with application to wind turbine simulation data

Many important systems, such as wind turbines, helicopters and turbomachinery, must be modeled with linear time-periodic equations of motion to correctly predict resonance phenomena. Time periodic effects in wind turbines might arise due to blade-to-blade manufacturing variations, stratification in the velocity of the wind with height and changes in the aerodynamics of the blades as they pass the tower. These effects may cause parametric resonance or other unexpected phenomena, so it is important to properly characterize them so that these machines can be designed to achieve high reliability, safety, and to produce economical power. This work presents a system identification methodology that can be used to identify models for linear, periodically time-varying systems when the input forces are unmeasured, broadband and random. The methodology is demonstrated for the well-known Mathieu oscillator and then used to interrogate simulated measurements from a rotating wind turbine. The measurements were simulated for a 5 MW turbine modeled in the HAWC2 simulation code, which includes both structural dynamic and aerodynamic effects. This simulated system identification provides insights into the test and measurement requirements and the potential pitfalls, and simulated experiments such as this may be useful to obtain a set of time-periodic equations of motion from a numerical model, since a closed form model is not readily available by other means due to the way in which the aeroelastic effects are treated in the simulation code.     

1．0 MW 变速恒频异步风力发电机组设计改型

通过阐述兰电（ LEC）与沈工大风能研究所合作研制的FD60-1000样机的设计方案,介绍主要部件风轮、叶片翼型、塔筒改型为FD65-1000风电机组,通过试验得到低风速频率集中的地域,风电机组的发电量明显比样机的发电量要高,而且在接近额定风速区域功率曲线时基本和设计的理论功率曲线接近吻合,通过叶片改型气动外形和分析效果良好。     

极端服役环境下的风电机组塔架结构参数优化研究

以大型风电机组塔架为对象,开展了极端服役环境下的塔架结构参数优化设计研究。采用壁厚分段式线性变化结构对塔架进行描述,介绍了基于BEM理论的风电机组气动载荷分析方法,运用有限元仿真分析塔架结构参数与极限载荷作用下的应力以及结构参数与固有频率的关联特性,采用支持向量机(SVM)方法分别构建了结构参数与应力、固有频率的快速计算模型。以质量最小为目标,强度、固有频率和边界条件为约束对塔架结构参数进行了设计优化,引入遗传算法(GA)进行优化求解。对某2MW风电机组塔架进行实例设计研究,结果表明优化后的塔架质量减小3.5%。      

动态气动载荷和构件振动对风力机气弹特性的影响分析

通过建立气弹耦合分析模型,研究叶片、塔架等构件的耦合振动对叶根气弹载荷的影响以及在静、动态气动模型下的叶根和塔底气弹载荷的差异。采用"超级单元"模型,将叶片、塔架和主轴离散为通过转动铰和弹簧、阻尼器连接的刚体系统,以反映这类构件较大的弹性变形和非线性振动。在叶素动量理论(Blade element momentum,BEM)基础上,引入Beddoes-Lesihman动态失速模型,以反映气动载荷的动态特性。应用计算多体动力学理论和风力机气动模型,建立受约束的风力机系统气弹耦合方程。算例以某5 MW风力机为研究对象,通过施加不同的约束条件,研究风轮以外其他构件振动对叶根气弹载荷的影响;通过静、动态气动分析模型,考察叶根和塔底气弹载荷的动态耦合效应。分析表明,塔架、主轴等构件的运动会显著影响叶根的气弹载荷;叶片的动态失速特性也对叶根的气弹载荷和疲劳载荷谱有较明显的影响。研究工作对于保证风力机安全稳定运行和疲劳寿命设计有重要的作用。