Servo-aeroelastic tailoring of wind turbines using new active-to-passive control systems

使用新型主动到被动控制系统对风力涡轮机进行伺服气动弹性定制

• 批准号: EP/N006127/1
• 负责人: Paul Weaver
• 金额: $ 70.02万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FN006127%2F1
• 关键词: Servo; aeroelastic; tailoring; wind; turbines

In recent years, the cost of energy produced by renewable supplies has steadily decreased. This factor, together with socio-economical reasons, has made renewable energies increasingly competitive, as confirmed by industry growth figures. Considering wind turbines (WTs), there are some interesting technical challenges associated with the drive to build larger, more durable rotors that produce more energy, in a cheaper, more cost efficient way. The rationale for moving towards larger rotors is that, with current designs, the power generated by WTs is theoretically proportional to the square of the blade length. Furthermore, taller WTs operate at higher altitudes and, on average, at greater wind speeds. Hence, in general, a single rotor can produce more energy than two rotors with half the area. However, larger blades are heavier, more expensive and increasingly prone to greater aerodynamic and inertial forces. In fact, it has been shown that they exhibit a cubic relationship between length and mass, meaning that material costs, inertial and self-weight effects grow faster than the energy output as the blade size increases. In addition, larger blades also have knock-on implications for the design of nacelle components.The wind-field through which the rotor sweeps varies both in time and space. Consequently, the force and torque distributions for the blades exhibit strong peaks at frequencies which are integer multiples of the rotor speed. Additional peaks are induced by lightly damped structural modes. The loads on the blades combine to produce unbalanced loads on the rotor which are transmitted to the hub, main bearing and other drive-train components. These unbalanced loads are a major contribution to the lifetime equivalent fatigue loads for some components which could cause premature structural failure. As the size of the blades increase, the unbalanced loads increase and the frequency of the spectral peaks decrease. Hence, they have an increasing impact as the size of the turbines become bigger.In this scenario, the demand for improvements in blade design is evident. The notion of increasingly mass efficient turbines, which are also able to harvest more energy, is immediately attractive.The viability of a novel adaptive blade concept for use with horizontal axis WTs is studied in this project. By suitably tailoring the elastic response of a blade to the aerodynamic pressure it could be possible to improve a turbine's annual energy production, whilst simultaneously alleviating structural loads. These improvements are obtained in a passive adaptive manner, by exploiting the capabilities that structural anisotropy and geometrically induced couplings provide. In particular, induced elastic twist could be used to vary the angle of attack of the blade sections according to power requirements, i.e. the elastic twist is tailored to change with wind speed proportionally to the bending load. The adaptive behaviour allows the blade geometry to follow the theoretically optimum shape for power generation closely (which varies as a function of the far field wind speed). This concept retains the load alleviation capability of previously proposed designs, whilst simultaneously enhancing energy production. Structurally, the adaptive behaviour is achieved by merging the bend-twist coupling capabilities of off-axis composite plies and of a swept blade planform. Potentially, an adaptive blade, controlled only by generator torque, could perform to power standards comparable to that of the current state-of-the-art-while greatly reducing complexity, cost and maintenance of wind turbines, by challenging the need for active pitch control systems.

近年来，可再生能源供应的能源成本稳步下降。这一因素，加上社会经济原因，使可再生能源的竞争日益激烈，行业增长数据证实了这一点。考虑到风力涡轮机(WTS)，在以更便宜、更具成本效益的方式制造更大、更耐用的转子以产生更多能源的过程中，存在一些有趣的技术挑战。转向更大转子的理由是，在目前的设计中，WTS产生的功率理论上与叶片长度的平方成正比。此外，更高的WTS在更高的海拔和平均风速下运行。因此，一般来说，一个转子可以产生比两个转子面积一半的更多的能量。然而，更大的叶片更重，更昂贵，越来越容易受到更大的空气动力和惯性力。事实上，已经证明它们呈现出长度和质量之间的立方关系，这意味着随着叶片尺寸的增加，材料成本、惯性和自重效应的增长速度快于能量输出。此外，较大的叶片对机舱部件的设计也有连锁反应。旋翼掠过的风场在时间和空间上都不同。因此，叶片的力和扭矩分布在转子转速的整数倍频率处显示出强烈的峰值。附加峰值是由轻微阻尼的结构振型引起的。叶片上的载荷结合在一起，在转子上产生不平衡载荷，这些载荷传递到轮毂、主轴承和其他传动系统部件。这些不平衡载荷是某些构件寿命当量疲劳载荷的主要贡献，这些载荷可能会导致结构过早失效。随着叶片尺寸的增大，不平衡载荷增大，谱峰频率减小。因此，随着涡轮机的尺寸变得更大，它们的影响也越来越大。在这种情况下，改进叶片设计的需求是显而易见的。质量效率越来越高的涡轮机也能够收集更多的能量，这一概念立即引起了人们的兴趣。在这个项目中，研究了一种新的自适应叶片概念用于水平轴风力机的可行性。通过适当地调整叶片对气动压力的弹性响应，可以提高涡轮机的年发电量，同时减轻结构负荷。这些改进是通过利用结构各向异性和几何诱导耦合提供的能力以被动自适应的方式获得的。特别是，诱导弹性扭转可以用来根据功率要求改变叶片截面的攻角，即弹性扭转被定制为与弯曲载荷成比例地随风速变化。这种自适应特性使叶片几何形状能够紧跟理论上的最佳发电形状(该形状随远场风速变化)。这一概念保留了以前提议的设计的负荷缓解能力，同时提高了能源生产。在结构上，自适应行为是通过融合离轴复合材料层和后掠式叶片平台的弯扭耦合能力来实现的。潜在地，只由发电机扭矩控制的自适应叶片可以达到与当前最先进水平相当的功率标准，同时通过挑战对主动变桨距控制系统的需求，极大地降低风力涡轮机的复杂性、成本和维护。

项目成果

Efficient structural optimisation of a 20 MW wind turbine blade

20 MW 风力发电机叶片的高效结构优化

• DOI: 10.1088/1742-6596/1618/4/042025
• 发表时间: 2020
• 期刊: Conference Series
• 作者: Scott S

Preliminary validation of ATOM: an aero-servo-elastic design tool for next generation wind turbines

ATOM 的初步验证：下一代风力涡轮机的气动伺服弹性设计工具

• DOI: 10.1088/1742-6596/1222/1/012012
• 发表时间: 2019
• 期刊: Conference Series
• 作者: Scott S

Finite Beam Elements for Variable Stiffness Structures

可变刚度结构的有限梁单元

• DOI: 10.2514/1.j056898
• 发表时间: 2018
• 期刊: AIAA Journal
• 影响因子: 2.5
• 作者: Macquart T

Corotational Finite Element Formulation for Static Nonlinear Analyses with Enriched Beam Elements

• DOI: 10.2514/1.j058441
• 发表时间: 2020-05-01
• 期刊: AIAA JOURNAL
• 影响因子: 2.5
• 作者: Macquart, T.;Scott, S.;Pirrera, A.
• 通讯作者: Pirrera, A.

Optimisation of composite structures - enforcing the feasibility of lamination parameter constraints with computationally-efficient maps

• DOI: 10.1016/j.compstruct.2018.03.049
• 发表时间: 2018-05
• 期刊: Composite Structures
• 影响因子: 6.3
• 作者: T. Macquart;V. Maes;M. T. Bordogna;A. Pirrera;P. Weaver