Towards First-Principles Based Wake and Wake Interaction Models for Wind-Farm Layout Optimization

建议编号：1236124机构：田纳西大学查塔努加分校标题：基于第一原理的尾迹和尾迹交互模型风电场布局优化多年来，随着全球大型风电场的建设，风能已成为一种很有前途的可再生能源。这些风电场利用多兆瓦的风力涡轮机生产数百兆瓦的电力。风力涡轮机的运行受到许多因素的影响，然而，吸入其他涡轮机的尾迹会导致功率输出减少，涡轮叶片上的动态负荷增加。为了将风电场的成本降到最低，涡轮机通常位于很近的位置，导致风电场中的许多尾迹相互作用和合并。以前的研究表明，根据风电场布局的不同，尾迹造成的功率损失估计在5%到20%之间。尽管对风力机尾迹的建模已经是近30年的研究课题，但尾迹相互作用的分析通常使用简单的尾迹模型，这些模型使用一组显式方程或解析表达式来预测尾迹中的速度和其他流动变量。利用S的计算资源，在不引入尾流模型的情况下，通过求解N-S方程，即可对多台旋转叶片风力机进行高分辨率数值模拟。虽然这种方法将提供具有尾流相互作用的风轮机流动的更高保真度表示，但计算机运行时间将从几天到几周不等。因此，需要具有既高保真又足够经济的改进的现场模拟模型和尾迹模型，以执行有效设计和优化风电场布局所需的大量模拟情况，从而最小化尾迹摄入的不利影响。此外，通过与不断更新的风气候(风速和风向)预报相结合，这种组合模型可以用于改善对现有风力发电场发电量的估计。准确的发电量预测对于风电场的经济运行和减少电网稳定性问题是必不可少的。本项目将探索两个新的、高保真、低成本的风力机尾迹和尾迹相互作用计算模型。第一种是基于一次/二次流近似的抛物型Navier-Stokes模型，该模型允许空间推进解而不需要对压力梯度进行任何近似。它既可用于与时间无关的涡轮盘模型的定常模式，也可用于非定常模式的旋转叶片模型。它将改进现有的模型，不仅适用于远尾迹，也适用于近尾迹区域。其模拟通过风电场的流动的计算成本将比Navier-Stokes模拟低得多(数量级)。尾迹和尾迹相互作用的第二个模型将涉及使用适当的正交分解或动态模式分解等技术将Navier-Stokes模拟分解成模式。与抛物型Navier-Stokes模型相比，该模型将显著降低计算成本。在风电场布局优化方面，这项研究将探讨将全局优化算法与基于梯度的算法相结合的方法，以缓解它们的不足并减少整体优化时间。位于田纳西大学查塔努加分校的综合研究和教育中心SimCenter参与了广泛的STEM活动，以支持激发学生对K-12科学和数学相关学科的兴趣。在一年的时间里，它定期接待数十名K-12学生小组。它还维护了一个专门提供与STEM相关的资源的网站。作为这项拟议工作的一部分，这些活动将扩大，以回应当地博物馆对合作接触更广泛受众的兴趣。将创建一个风力发电场的桌面模型，并将其用作参观的一部分。这将使学生能够亲身体验运行中的风力涡轮机。高中生、本科生和研究生将参与这项活动的各个方面。高中生和本科生将参与开发桌面模型，还将为SimCenter网站开发软件应用程序。此外，本科生将帮助生成模拟所需的计算网格，研究生将实施本提案中概述的方法。

PI: Sreenivas, KidambiProposal Number: 1236124Institution: University of Tennessee ChattanoogaTitle: Towards First-Principles Based Wake and Wake Interaction Models for Wind-Farm Layout OptimizationWind energy has become a promising renewable energy source over the years with large wind farms being built worldwide. These wind farms produce hundreds of megawatts (MW) of power utilizing multi-megawatt wind turbines. The operation of a wind turbine is affected by many factors, however the ingestion of wakes from other turbines results in reduced power output and increased dynamic loading on the turbine blades. In an effort to minimize the cost of the wind farm, turbines are typically located in close proximity, resulting in the interaction and merging of many wakes in the wind farm. Previous studies indicate that estimated power losses due to wakes can range from 5% to 20%, depending upon the wind farm layout.Although modeling of wind turbine wakes has been a research topic for nearly 30 years, analysis of wake interactions has typically used simple wake models that predict velocity and other flow variables in the wake using a set of explicit equations or analytical expressions. With today?s computational resources it is now possible to perform high-resolution simulations for multiple wind turbines with rotating blades by solving the Navier-Stokes equations without introducing a wake model. Although this approach would provide a higher fidelity representation of wind-turbine flow with wake interaction, the computer run time would range from days to weeks. Thus, there is need to have improved field simulation models and wake models that are both high fidelity and sufficiently economical to perform the large number of simulation cases required to effectively design and optimize the layouts of wind farms so as to minimize the adverse affects of wake ingestion. Additionally, such a combined model could be used to improve estimates of power production from existing wind farms by integration with continually updated wind climate (speed and direction) forecasts. Accurate power production forecasts are necessary for economical operation of the wind farm and to reduce power-grid stability issues.This project will explore two new, high-fidelity, low-cost computational models for wind-turbine wakes and wake interactions. The first is a new Parabolic Navier-Stokes model based on a primary/secondary flow approximation that allows spatial marching solution without any approximation for pressure gradients. It can be used in steady mode with time-independent turbine-disk models or in unsteady mode with rotating-blade models. It will improve upon existing models by being applicable not only in the far wake but also in the near-wake region. Its computational cost for simulating flow through a wind farm would be substantially lower (orders of magnitude) than a Navier-Stokes simulation. The second model for wake and wake-interaction will involve decomposing Navier-Stokes simulations into modes using techniques such as Proper Orthogonal Decomposition or Dynamic Mode Decomposition. This model will significantly reduce the computational cost compared to the Parabolic Navier-Stokes model. In the area of wind farm layout optimization, this study will address methods for coupling a global optimization algorithm with a gradient-based algorithm to mitigate their deficiencies and reduce overall wall-clock time for optimization.The SimCenter, an integrated research and education center within the University of Tennessee at Chattanooga, has been involved in a broad range of STEM activities that support the goal of stimulating interest among students in K-12 in science and math related disciplines. It regularly hosts dozens of groups of K-12 students over the course of the year. It also maintains a website dedicated to STEM related resources. As part of this proposed effort, these activities will be expanded to respond to interest from local museums in collaborations to reach a wider audience. A table-top model of a wind farm will be created and used as part of the tours that are conducted. This will enable students to have hands-on experience with functioning wind turbines. High school, undergraduate and graduate students will be involved in various aspects of this activity. The high-school and undergraduate students will be involved in developing the table-top model and will also develop software applications for the SimCenter website. In addition, undergraduate students will assist in the generation of computational grids required for the simulations, and graduate students will implement the approaches outlined in this proposal.