Chaired by: F. Porté-Agel, J. Jonkman
16:30
Comparison of Different Measurement Techniques and CFD Simulation in Complex Terrain
Christoph Schulz | University of Stuttgart | Germany
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Authors:
Christoph Schulz | University of Stuttgart | Germany
Martin Hofsäß | Germany
Jan Anger | Germany
Alexander Rautenberg | Germany
Thorsten Lutz | Germany
Po-Wen Cheng | Germany
Jens Bange | Germany
This paper deals with a comparison of data collected by measurements and a simulation for a complex terrain test site in southern Germany. Lidar, met mast, unmanned aerial vehicle (UAV) measurements of wind speed and direction and Computational Fluid Dynamics (CFD) data are compared to each other. The site is characterised regarding its flow features and the suitability for a wind turbine test field. A Delayed-Detached-Eddy-Simulation (DES) was employed using measurement data to generate generic turbulent inflow. A good agreement of the wind profiles between the different approaches was reached. The terrain slope leads to a speed-up, a change of turbulence intensity as well as to flow angle variations.
16:50
Wind Power Forecasting techniques in complex terrain: ANN vs. ANN-CFD hybrid approach
Dr. Davide Astolfi | University of Perugia | Italy
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Authors:
Dr. Davide Astolfi | University of Perugia | Italy
Francesco Castellani | Italy
Matteo Mana | Italy
Massimiliano Burlando | Italy
Catherine Meissner | Italy
Emanuele Piccioni | Italy
Due to technology developments, renewable energies are becoming competitive against fossil sources and the number of wind farms is growing, which have to be integrated into power grids. Therefore, accurate power forecast is needed and often operators are charged with penalties in case of imbalance. Yet, wind is a stochastic and very local phenomenon, and therefore hard to predict. It has a high variability in space and time and wind power forecast is challenging. Statistical methods, as Artificial Neural Networks (ANN), are often employed for power forecasting, but they have some shortcomings: they require data sets over several years and are not able to capture tails of wind power distributions. In this work a pure ANN power forecast is compared against a hybrid method, based on the combination of ANN and a physical method using computational fluid dynamics (CFD). The validation case is a wind farm sited in southern Italy in a very complex terrain, with a wide spread turbine layout.
17:10
Intercomparison of terrain-following coordinate transformation and immersed boundary methods in large-eddy simulation of wind fields over complex terrain
Dr. Jiannong Fang | Ecole Polytechnique Fédérale de Lausanne (EPFL) | Switzerland
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Authors:
Dr. Jiannong Fang | Ecole Polytechnique Fédérale de Lausanne (EPFL) | Switzerland
Fernando Porté-Agel | Switzerland
Accurate modeling of complex terrain, especially steep terrain, in the simulation of wind fields remains a challenge. In this paper, we perform an intercomparison of a terrain-following coordinate transformation (TFCT) method and an immersed boundary method (IBM) in large-eddy simulation of a turbulent wind field over a three-dimensional hill, for which wind-tunnel measurements are available for validation. The slopes of the three-dimensional hill are not steep and, therefore, TFCT can be applied. It is shown that the implementation errors in IBM lead to large discrepancies between the results obtained by TFCT and IBM near the surface. The effects of different schemes used to implement wall boundary conditions in IBM are studied. The source of errors and possible ways to improve the IBM implementation are discussed.
17:30
The fence experiment - a first evaluation of shelter models
Prof. Jakob Mann | Technical University of Denmark | Denmark
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Authors:
Prof. Jakob Mann | Technical University of Denmark | Denmark
Alfredo Peña | Denmark
Andreas Bechmann | Denmark
Davide Conti | Denmark
Nikolas Angelou | Denmark
We present a preliminary evaluation of shelter models of different degrees of complexity using full-scale lidar measurements of the shelter on a vertical plane behind and orthogonal to a fence. Model results accounting for the distribution of the relative wind direction within the observed direction interval are in better agreement with the observations than those that correspond to the simulation at the center of the direction interval, particularly in the far-wake region, for six vertical levels up to two fence heights. Generally, the CFD results are in better agreement with the observations than those from two engineering-like obstacle models but the latter two follow well the behavior of the observations in the far-wake region.