Open AccessA simple analytical wind park model considering atmospheric stability
Author(s) -
Emeis S.
Publication year - 2010
Publication title -
wind energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.743
H-Index - 92
eISSN - 1099-1824
pISSN - 1095-4244
DOI - 10.1002/we.367
Subject(s) - offshore wind power , roughness length , wind speed , wind power , wind profile power law , atmospheric instability , environmental science , surface roughness , meteorology , surface finish , submarine pipeline , momentum (technical analysis) , wind stress , wind gradient , flux (metallurgy) , log wind profile , marine engineering , atmospheric sciences , geology , engineering , geography , physics , geotechnical engineering , materials science , mechanical engineering , electrical engineering , finance , quantum mechanics , economics , metallurgy
The analytical top‐down wind park model by Emeis and Frandsen1 is enhanced by consistently making both the downward momentum flux and the momentum loss at the rough surface dependent on atmospheric stability. Specifying the surface roughness underneath the turbines in a wind farm in the model gives the opportunity to investigate principal differences between onshore and offshore wind parks, because the roughness length of the sea surface is two to three orders of magnitude lower than the roughness length of land surfaces. Implications for the necessary distance between single turbines in offshore wind farms and the distance between neighbouring wind parks are computed. It turns out from the model simulations that over smooth surfaces offshore the wind speed reduction at hub height in a wind farm is larger than over rough onshore surfaces given the same density of turbines within the park. Mean wind profiles within the park are also calculated from this model. Offshore wind farms must have a larger distance between each other in order to avoid shadowing effects of the upstream farm. Copyright © 2009 John Wiley & Sons, Ltd.