Rayleigh Distribution - Electrical Power from a Wind Turbine

The curve below shows the results of a sample calculation to estimate the electrical power output per square metre of swept area for a wind turbine for varying Rayleigh wind speeds.  The curve is based on a arbitrary set of values thought to be typical of a medium sized wind turbine.  The parameters are illustrative and it is important to obtain site specific parameters for a specific project evaluation.

Follow the link to see the parameters used for the calculation and discussion of their use.  A summary of the parameters is shown in the table below:

Parameter	Value
Altitude	Sea Level
Coef. of Performance	See Graph
Conversion Efficiency	70%
Operating Range	2 - 25 m/sed

An underlying assumption in the calculation is that the annual distribution of the wind speed is a Rayleigh Distribution (itself a special case of the Weibull distribution in which the shape factor is set to 2.0).  for a given project is is important to determine that this assumption is valid.  Depending on the nature of the site, another form of model may be appropriate, common alternatives being the Weibull with appropriate shape factors.

Page Updated 31-Jan-2005

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