Dresden 2011 – wissenschaftliches Programm

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AKE: Arbeitskreis Energie

AKE 8: Offshore Wind

AKE 8.1: Hauptvortrag

Mittwoch, 16. März 2011, 11:15–11:45, BEY 118

The Physics of Wind Park Optimization — •Stefan Emeis — Institut für Meteorologie und Klimaforschung, Atmosphärische Umweltforschung, Karlsruher Institut für Technologie, Garmisch-Partenkirchen

Power generation from wind turbines depends on wind and turbulence conditions in the atmospheric boundary layer (ABL). Future large wind parks are planned offshore amongst other reasons because wind speeds are higher and turbulence intensities are lower offshore than onshore. But lower turbulence intensities lead to more persistent turbine wakes, which should be taken into account in the optimal design of offshore wind parks. After an introduction into the basic meteorological features which influence wind power generation, an analytical model for wind park optimization based on equilibrium between momentum extraction by the turbines and momentum supply by vertical turbulent momentum fluxes from higher atmospheric layers above the wind park is presented here. It estimates the magnitude of the wind speed reduction within a large wind park and the extension of the park wake as a function of wind speed, ABL thermal stratification, surface roughness, wind turbine drag, turbine density in the park and the turbulence production by the turbines. The model simulates a clear increase of the wind speed reduction and wake length with increasing atmospheric stability and decreasing surface roughness. I.e., wind speed reduction and park wake length are considerably larger for offshore wind parks than for onshore parks. This model can be used for optimizing the distance between the turbines within a wind park as well as for optimizing the distance between adjacent wind parks.