weibull PDF

[satish1960gupta]

Q 1
Which method of parameter estimation is used for fitting weibull PDF to the data.
What are the formulae?
Q2 What is the formula used for extrapolating wind speed to other heights?
Q3 How roughness coefficient/ class of roughness determined?

[Morten]

WAT imports the mean wind climates of WAsP. I will only make short comment here and refer to the WAsP help file, similar questions in the WAsP section of this forum, and the European Wind Atlas for detailed information.


A1
WAsP fits the PDFs by matching two statistics of the observations with the Weibull probablity distribution. These statistics are the average cube of the wind speed and the probability of winds above the empirical mean wind speed. This usually gives a good fit in the upper part of the wind distributions which is most important for the power production. NB: The mean wind speed of the Weibull fit will not match the data perfectly.


A2
The extrapolation is done with the WAsP model. There is no simple formula.


A3
Please read about roughness classification in the help file of WAsP, the help file of the WAsP Map Editor and the European Wind Atlas.


Cheers,
Morten

[satish1960gupta]

Thank you