Speed Discrepancy in WAsP

[carriv9]

Good Afternoon,

My question today involves the wind speed discrepancy between the mean speed from my measured met tower and the mean speed (U) in the observed wind climate. My observed wind climate is showing a mean speed (U) that is around 2% to 3% (or .20 m/s) lower than my measured met tower mean wind speed. I understand that WAsP forces the measured data to fit a standard Weibull frequency distribution, however, is there a way to correct this 2-3% discrepancy? And how much is this discrepancy affecting my AEP? I noticed that the observed wind climate has a "Quality-Speed Discrepancy" table, which I assume shows the discrepancy between these two for each sector.

Thank you.

[Mark Kelly]

Good Afternoon,

My question today involves the wind speed discrepancy between the mean speed from my measured met tower and the mean speed (U) in the observed wind climate. My observed wind climate is showing a mean speed (U) that is around 2% to 3% (or .20 m/s) lower than my measured met tower mean wind speed. I understand that WAsP forces the measured data to fit a standard Weibull frequency distribution, however, is there a way to correct this 2-3% discrepancy? And how much is this discrepancy affecting my AEP? I noticed that the observed wind climate has a "Quality-Speed Discrepancy" table, which I assume shows the discrepancy between these two for each sector.

Thank you.

Hello,
We remind that the power-density is generally more important than the mean wind speed in the Weibull-fit. You may notice that the Weibull-fit power density is likely within 1% of the raw/histogrammed data's power density. This impacts the AEP more than the mean wind speed, as documented (somewhat) in the help file--and as we teach in the WAsP course.
Look at the bottom of the OWC table in WACA, and you can see (yellow) boxes showing the power-density numbers; to the far right in this table a the 'quality' is shown for power-density, i.e. dimensionless error in percent (%).

With kind regards,
--Dr. Mark Kelly
Wind Energy Dept., Risø Lab/Campus, Danish Tech. University