风力机尾流数值模拟及风电场机组布局优化研究

发布时间：2018-07-16 21:48

【摘要】：风经过旋转的风轮时由于部分动能被吸收转化为机械能,风力机下游出现风速下降、湍流强度增加等现象,这被称为风力机的尾流效应。前人的研究报告中指出,在当前投产运营的风电场中,尾流效应会导致风电场发电功率降低15%~50%不等。因此,深入研究风力机尾流效应具有重要意义。微观选址工作是风工程项目运营的前提和基础,在开展风电场微观选址工作时,应合理布置各风力机的位置,尽量避开风力机尾流的影响,提高风电场的风能利用率和综合经济效益。近年来,随着风能产业的蓬勃发展,一些地形复杂的风电场开始投产运营。复杂风电场的地形起伏变化较大、影响因素众多,增大了复杂地形风电场微观选址的难度。本文围绕风力机尾流数值模拟、平坦地形风电场微观选址、复杂地形风电场流动分布及其机组布局优化等方面开展了如下研究工作:(1)提出适用于风力机尾流数值模拟的修正AD/RANS方法,并对其计算精度、鲁棒性和通用性进行测试。本文结果和前人的研究结果一致表明,当采用Actuator Disc(广义致动盘,简称AD)方法结合RANS模型(这二者的结合为AD/RANS)模拟风力机尾流时,得到的尾流流场与实验结果存在一定的误差。于是,依据AD方法的简化思想、RANS湍流模型的特点、大气边界层的属性等,分析误差的来源,基于扎实的理论依据对湍流模型提出修正,发展了两种适用于风力机尾流预测的修正AD/RANS方法。通过单台风力机尾流、两台风力机混合尾流、多台风力机混合尾流和偏尾流等情况的数值模拟,结果表明本文发展的修正AD/RANS方法表现较好、计算精度较高,可作为一种基于CFD的数值方法,应用于风力机尾流流动机理的研究。(2)基于风工程领域广泛使用的Jensen尾流模型(PARK尾流模型),发展一种较高精度的2D_k Jensen尾流模型。受制于目前的计算资源,在风工程领域应用较为广泛的依然是一些工程尾流模型。针对经典Jensen尾流模型存在的精度不足问题,提出一种更能准确反映风力机尾流流场分布情况的模型—2D_k Jensen尾流模型。通过近十个数值算例的验证,表明2D_k Jensen尾流模型不管是对风力机尾流中速度分布和湍流强度分布的预测还是对风电场发电量的评估,都表现了较好的计算性能。由此可以推测,该方法可应用于风电场微观选址工作,为开发商提供较为准确的风电场特征数据。(3)针对平坦地形风电场开展机组布局优化研究。基于前文所发展的可靠尾流模型—2D_k Jensen尾流模型评估风电场发电量,基于更贴近现实的成本模型评估风电场项目成本,采用高效率的优化算法和多样的优化策略对平坦地形风电场机组布局问题进行优化运算。结果中给出几组较优的机组布局图和各布局所对应的风电场特征参数供决策者根据需求进行选择。该工作对于现实中的平坦地形风电场微观选址工作具有一定的参考价值。(4)开展复杂地形风电场的流动分布及机组排布优化研究。建立复杂地形几何模型,研究复杂地形风电场周围的流动发展和变化规律。针对复杂地形风电场的微观选址工作,研究目前常用的解耦算法(分别计算尾流效应和地形效应然后将二者的结果线性叠加)与常规的耦合计算方法之间的误差。计算结果表明,针对本文选取的堤坝地形风电场,就计算到的速度大小而言,解耦算法会引入20%左右的误差。最后,对山地地形风电场进行机组布局优化研究,其结果可为当前的复杂地形风电场建设提供参考和指导。
[Abstract]:The wind passing through a rotating wind wheel is converted into mechanical energy due to the absorption of some kinetic energy, and the wind speed decreases and the turbulence intensity is increased in the downstream of the wind turbine. This is called the wake effect of the wind turbine. In the previous research report, the wake effect in the current operation of the wind farm will lead to the reduction of the power generation power of the wind farm by 15%~50%. Therefore, it is of great significance to study the effect of wind turbine tail flow. The microcosmic location work is the prerequisite and foundation for the operation of wind engineering projects. In carrying out the micro location of the wind farm, the position of each wind turbine should be arranged reasonably, the wind turbine tail flow is avoided as far as possible, and the wind energy utilization rate and the comprehensive economic benefit of the wind farm are improved in recent years. With the vigorous development of the wind energy industry, some complex wind farms have begun to operate. The terrain fluctuation of complex wind farms has been changed greatly and the influence factors are numerous, and the difficulty of the micro location of the wind farm of complex terrain is increased. The following research work has been carried out on the dynamic distribution and the optimization of the layout of the unit. (1) a modified AD/RANS method is proposed for the numerical simulation of wind turbine tail flow, and its calculation accuracy, robustness and generality are tested. The results of this paper are in agreement with the results of previous studies, and the method of using the Actuator Disc (generalized actuated disk, AD) method is shown. Combining the RANS model (the combination of the two is AD/RANS) to simulate the wind turbine tail flow, there is a certain error in the wake flow field and the experimental results. Then, based on the simplified thought of the AD method, the characteristics of the RANS turbulence model and the properties of the atmospheric boundary layer, the source of the error is analyzed, and the turbulence model is amended based on a solid theoretical basis. Two modified AD/RANS methods are developed for wind turbine tail flow prediction. Through numerical simulation of single wind turbine tail flow, two wind turbine mixing tail flow, multi wind turbine mixing tail flow and partial tail flow, the results show that the modified AD/RANS method presented in this paper has better performance and higher calculation precision, which can be used as a kind of numerical value based on CFD. The method is applied to the study of the mechanism of wind turbine tail flow. (2) based on the widely used Jensen wake model (PARK wake model) in wind engineering, a high precision 2D_k Jensen wake model is developed. Under the current computing resources, some engineering wake models are still widely used in the field of wind engineering. The classic Jen is still used in the wind engineering field. The accuracy of the Sen wake model is insufficient. A model, 2D_k Jensen wake model, which can more accurately reflect the distribution of wind turbine wake flow field, is presented. Through the verification of nearly ten numerical examples, it is shown that the 2D_k Jensen wake model is the prediction of the velocity distribution and the distribution of turbulence intensity in the tail flow of the wind turbine or to the wind farm. This method can be applied to the micro location of the wind farm and provide more accurate wind power characteristics data for the developers. (3) the research on the optimization of the unit layout for flat topographic wind farms. Based on the reliable wake model developed in the previous paper, 2D_k Jensen tail flow The model estimates wind power generation, and based on the more realistic cost model to evaluate the cost of wind farm project. Using the efficient optimization algorithm and various optimization strategies to optimize the layout problem of flat topographic wind farm units, several groups of better unit layout and the characteristic parameters of wind farms corresponding to the layout are given. The number is for the decision makers to choose according to the needs. This work has a certain reference value for the actual flat topographic wind farm micro location work. (4) carry out the flow distribution of the complex terrain wind farm and the optimization of the arrangement of the unit arrangement. In view of the micro location of the wind farm in complex terrain, the error between the commonly used decoupling algorithms (calculation of the wake effect and the topographic effect and then the linear superposition of the results of the two) with the conventional coupling calculation method is studied. The calculation results show that the calculated velocity is calculated according to the wind electric field of the embankment topography selected in this paper. As a result, the decoupling algorithm will introduce about 20% of the error. Finally, the optimization of the layout of the wind farm in the mountain terrain is studied. The results can provide reference and guidance for the construction of the current complex terrain wind farm.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM614

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