Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
Thanks. Some further questions if you have the time...

Do you use raw NOAA data or GFS + validation using other meteorological models? GFS afaik underestimates wind speeds, especially for higher speeds, so I would be curious to see how one corrects for that.

As far as wake losses are concerned, I suppose your regular 2.5/5 diameter rule does not apply... but why is that? Is it because wake effects do not move linearily with rated power?

Rien n'est gratuit en ce bas monde. Tout s'expie, le bien comme le mal, se paie tot ou tard. Le bien c'est beaucoup plus cher, forcement. Celine

by UnEstranAvecVueSurMer (holopherne ahem gmail) on Thu Jul 19th, 2012 at 04:27:25 PM EST
[ Parent ]
What 2.5/5 diameter rule?

Spacing is determined by the energy-weighted wind rose.  But it takes anywhere from 12 to >20 diameters before upwind turbulence has decayed and boundary layer mixing has replenished the energy taken out by the upwind row.

No project developer uses such spacing today, which puts extra load cycles on the downwind turbines in any direction.. There should be a happy medium, with well understood tradeoffs between energy capture and excessive load avoidance. But proper spacing greatly increases cable costs as well, so... it's often not under major consideration.

We'll have to wait for more operational data from the low rpm greater diameter WTs to see how great the problem is before there's a chance of establishing a rule of thumb. This can also be an underestimated problem between projects, when they are clustered with a narrow shipping lane between.

The science is obtained incrementally.

"Life shrinks or expands in proportion to one's courage." - Ana´s Nin

by Crazy Horse on Fri Jul 20th, 2012 at 08:06:20 AM EST
[ Parent ]
Offshore these days is typically spaced 7 diameters apart in the prevailing wind direction and 5 in the other direction.

Wind power
by Jerome a Paris (etg@eurotrib.com) on Fri Jul 20th, 2012 at 12:16:24 PM EST
[ Parent ]


Occasional Series