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Rayleigh Wind Speed Explanation

I'll give the details first, then an easier to understand explanation in the 2nd and 3rd paragraphs.

Complex version:

The Rayleigh Wind Speed that I am putting in the data pages of my web site may seem a little strange to you.  What it does is level the resource that the turbine had available as best as can be done.  Using the actual wind speed distribution that the wind turbine experienced for the month, I cube the velocities, add them up, then take the cube root of them.  I call this the effective velocity.  Next, I plug a wind speed into the Rayleigh distribution calculation.  I cube the wind speeds for the Rayleigh distribution just like I did with the actual wind speed distribution, sum them up, and take the cube root of that number.  I keep adjusting the input wind speed to the Raleigh distribution until the effective velocity of the Rayleigh distribution matches the effective velocity that the wind turbine actually experienced.  

Easier version:

In english, now!  If I report the average wind speed of 13.25 mph, and a Rayleigh wind speed of 13.6 mph, that says that my 13.25 mph winds had the same energy as a 13.6 mph average wind with a Rayleigh distribution.  The significance of this is that manufacturers assume a Rayleigh distribution in estimating the energy a turbine would produce given a certain wind speed.  The DOE wind energy classes relate, say a wind class of 4 to a wind speed from 12.5-13.4 mph.  The wind speed they give is the Rayleigh wind speed I am using.  They have adjusted expected output to the wind speed distributions expected for the stated area.

As far as I am concerned, the ONLY way to compare turbine output is using the Rayleigh Wind Speed.  That correlates my data to what the manufacturers expect, and what the DOE wind classes suggest.

So, if you want to see if a turbine is meeting manufacturer specifications, you would need to use the Rayleigh wind speed I calculate instead of my actual average wind speed.