Weibull Fit (2009-10-14)

[Old Forum Archivist]

Anemometers are usually only calibrated between 4-16 m/s. All values of my wind speeds which should read 0 m/s, actually read .2775 m/s because of the calibration offset. So all values under 4 m/s are incorrect because of the calibration curve programmed into the data logger. What I wonder is does WAsP know this? When WAsP calculates the Weibull curve, and thus AEP based on the different sectors, is this taken into account. The Weibull parameters must be inaccurate, right? If I convert all my wind speeds back to Hz using my calibration curve, and use those in WAsP with my offset and slope, will I get a more accurate Weibull curve and AEP estimates?

Thanks

Danny

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Hi,



The normal procedure would be to take out any systematic errors prior to the actual analysis. You can process the measurements yourself by writing a small program or by using a spread sheet program. Also you can correct for certain errors (offsets) in the WAsP Climate Analyst.


Kees

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Kees is right: the place to fix this is in the Climate Analyst (or in Excel). The time series data is reorganised into histograms (observed wind climates) for input to WAsP.



Don't forget that you can set the calm threshold for interpreting time series data, and can also adjust the width of the first histogram bin. I don't quite understand your description of the anemometer calibration, but it should be possible to extract some meaningful data by making the relevant adjustments.

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