Journal ArticleDOI
Modelling and measuring flow and wind turbine wakes in large wind farms offshore
Rebecca Jane Barthelmie,Kurt Schaldemose Hansen,Sten Tronæs Frandsen,Ole Rathmann,J.G. Schepers,W. Schlez,John D. Phillips,K. Rados,Arthouros Zervos,E.S. Politis,P. Chaviaropoulos +10 more
TLDR
In this article, the authors compare different types of models from computational fluid dynamics (CFD) to wind farm models in terms of how accurately they represent wake losses when compared with measurements from offshore wind farms.Abstract:
Average power losses due to wind turbine wakes are of the order of 10 to 20% of total power output in large offshore wind farms. Accurately quantifying power losses due to wakes is, therefore, an important part of overall wind farm economics. The focus of this research is to compare different types of models from computational fluid dynamics (CFD) to wind farm models in terms of how accurately they represent wake losses when compared with measurements from offshore wind farms. The ultimate objective is to improve modelling of flow for large wind farms in order to optimize wind farm layouts to reduce power losses due to wakes and loads.
The research presented is part of the EC-funded UpWind project, which aims to radically improve wind turbine and wind farm models in order to continue to improve the costs of wind energy. Reducing wake losses, or even reduce uncertainties in predicting power losses from wakes, contributes to the overall goal of reduced costs. Here, we assess the state of the art in wake and flow modelling for offshore wind farms, the focus so far has been cases at the Horns Rev wind farm, which indicate that wind farm models require modification to reduce under-prediction of wake losses while CFD models typically over-predict wake losses. Further investigation is underway to determine the causes of these discrepancies. Copyright © 2009 John Wiley & Sons, Ltd.read more
Citations
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Journal ArticleDOI
A new analytical model for wind-turbine wakes
TL;DR: In this paper, a new analytical wake model is proposed and validated to predict the wind velocity distribution downwind of a wind turbine by applying conservation of mass and momentum and assuming a Gaussian distribution for the velocity deficit in wake.
Journal ArticleDOI
Wind-Turbine and Wind-Farm Flows: A Review
TL;DR: This review summarizes recent experimental, computational, and theoretical research efforts that have contributed to improving the understanding and ability to predict the interactions of ABL flow with wind turbines and wind farms.
Journal ArticleDOI
The impact of turbulence intensity and atmospheric stability on power deficits due to wind turbine wakes at Horns Rev wind farm
TL;DR: In this paper, the power deficit along rows of wind turbines have been determined for different inflow directions and wind speed intervals, and a method to classify the atmospheric stability based on the Bulk-Ri number has been implemented.
Journal ArticleDOI
Quantifying the Impact of Wind Turbine Wakes on Power Output at Offshore Wind Farms
Rebecca Jane Barthelmie,Sara C. Pryor,Sten Tronæs Frandsen,Kurt Schaldemose Hansen,J.G. Schepers,K. Rados,W. Schlez,A. Neubert,Leo E. Jensen,S. Neckelmann +9 more
TL;DR: In this article, a detailed data ensembles of power losses due to wakes at the large wind farms at Nysted and Horns Rev are presented and analyzed, and a number of ensemble averages are simulated with a range of wind farm and computational fluid dynamics models and compared to observed wake losses.
Journal ArticleDOI
Flow Structure and Turbulence in Wind Farms
TL;DR: In this article, the authors summarize current understanding of these flow phenomena through field studies, wind tunnel experiments, large-eddy simulations, and analytical modeling, emphasizing the most relevant features for wind farm design and operation.
References
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Book
An Introduction to Boundary Layer Meteorology
TL;DR: In this article, the boundary layer is defined as the boundary of a boundary layer, and the spectral gap is used to measure the spectral properties of the boundary layers of a turbulent flow.
Journal ArticleDOI
Analytical modelling of wind speed deficit in large offshore wind farms
Sten Tronæs Frandsen,Rebecca Jane Barthelmie,Sara C. Pryor,Ole Rathmann,Søren Ejling Larsen,Jørgen Højstrup,Morten Lybech Thøgersen +6 more
TL;DR: In this paper, the authors proposed a model for the wind speed deficit in wind farms and extended it to include both small and large wind farms extending over large areas, and the model handles a regular array geometry with straight rows of wind turbines and equidistant spacing between units in each row.
Journal ArticleDOI
Calculating the flowfield in the wake of wind turbines
TL;DR: In this article, a numerical model is described which can be used to calculate the wake flowfield of wind turbines and the effect of meteorological conditions on wake decay is examined in detail.
Journal ArticleDOI
Survey of modelling methods for wind turbine wakes and wind farms
TL;DR: In this paper, the authors provide an overview and analysis of different wake-modelling methods which may be used as prediction and design tools for both wind turbines and wind farms, and survey the available data concerning the measurement of wind magnitudes in both single wakes and wind turbines, and of loading effects on wind turbines under single and multiple wake conditions.