* either Socrates or Manuel, from Barcelona (like us)
Unfortunately, you can’t say much about Extreme wind events just by knowing a lot about Average winds. This is our humble conclusion after nearly 15 years** in the Wind Industry.
Having delivered upwards of 330,000 synthetic wind calculations worldwide, at Vortex we like to think that we know a lot about wind. However, our last challenge (estimating EXTREME winds beyond the usual Vref computations) has taught us a lesson in humility: there are not only many windy places (on Average) that never experience high Extreme wind events -which may seem anti-intuitive if you are new to business- but also the opposite is actually true what may lead to some unpleasant surprises and threaten your turbines’ integrity over their expected lifetime.
The above chart shows the scatterplot of 154 well-measured (according to Wind Industry Standards) annual Means (horizontal) vs. Maxima (vertical) at sites all around the world.
The correlation of these two variables is null (R2=0.08) and, for a given Mean, the “dispersion” of the Maxima may be of the order of 20m/s. Thus, apparently there is no simple rule-of-thumb to quickly estimate the Extreme speed if only the Average is known.
Faced with this challenges, you can probably guess our next move was to let the computers do the work, which we did it by combining our most powerful tool WRF-LES with the current availability of ERA5 Reanalysis dataset comprising at least 30 years of data usable as input for LES calculations.
The results are very encouraging as you can check in this in-house study showing that modelling is probably the most sensible way to approach this matter nowadays.
** Vortex was established in Barcelona in September 2005. It’s not long now until our company celebrates its 15th anniversary. No doubt that we’ll celebrate it together 😉