Problem with Wind Atlas Structure modification... (2004-04-26)

[Old Forum Archivist]

Hi,

when the wind atlas structure is modified using Project Configuration, the re-calculated AEP changes appreciably !

In my mind, the wind atlas structure, as a wind atlas representation, must not change the results.

Is this problem known ?

Is that a bug ?



Thank you for any help.



Philippe.

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Better late than never, as they say... sorry Philippe, your post was somehow forgotten.



Changing the default roughness lengths and default heights in the wind atlas, will affect the predictions, since WAsP needs to interpolate between the default values to obtain the values for the actual site and height. Ideally, this interpolation error should be small; however, it will increase if actual conditions are far from default/standard conditions. You may decrease the uncertainty by choosing default values that are close to and representative of your wind turbine sites (e.g. use the hub height as one of the standard heights in the wind atlas, or insert a standard roughness of, say, 0.001 m if your sites are in the desert or another low-roughness area).



This has always been a known issue (and not a bug), but probably an issue that deserves more attention in the future.



The WAsP Team @ Risø

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