Power output of offshore wind farms in relation to atmospheric stability

The Science of Making Torque from Wind 2012

Alblas, Laurens^1,3 ; Bierbooms, Wim^1 ; Veldkamp, Dick^1,2

Wind Energy Research Group (DUWIND), Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, Delft

2629 HS, Netherlands^1

Vestas Central Europe, PO Box 208, Arnhem

6800 AE, Netherlands^2

DNV GL, Veritasveien 1, Høvik

1322, Norway^3

关键词: Atmospheric stability;    Decay constants;    Near-neutral conditions;    Power out put;    Power production;    Production data;    Stability distributions;    Unstable conditions;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/555/1/012004/pdf
DOI  :  10.1088/1742-6596/555/1/012004

来源: IOP

【 摘 要 】

Atmospheric stability is known to influence wind farm power output, by affecting power losses due to wakes. This research tries to answer what atmospheric stability does to the power production and how conventional simulations using the Jensen wake model compare and can be improved. Data is used from two offshore wind farms, Egmond aan Zee (OWEZ) and North Hoyle. Stability distributions are determined using metmast data. By combining this data with the production data, the influence of stability on the power output is studied. It is found that very unstable conditions result in higher power output (i.e. smaller wake losses) than near-neutral conditions, and these again show higher power output than during very stable conditions. Differences in normalized power output of 10-20% exist between the very unstable and very stable conditions. Simulations can be improved by adapting the wake decay constant (WDC). Observed WDC values are k ≥ TI, as opposed to the conventional k ≈ 0.5TI. A hypothesis for further research is proposed regarding the influence of vertical turbulence.