Analysis of the influence of the wind speed profile on wind power production

Abstract

The characterization of wind speed and its variability at a site is important for wind resource assessment. The most readily available wind measurements are at 10 m above ground level. These measurements can then be extrapolated vertically to estimate wind power production. In this work, the Monin–Obukhov similarity method was implemented to estimate the wind speed vertical profile within the surface boundary layer for a southeast Mexican site, considering seasonal and diurnal variations of the surface boundary layer stability parameters. Additionally, a power-law method was implemented where the wind shear exponent was set following the International Electrotechnical Commission (IEC) standard and using a variable wind shear exponent. The results showed that the log-law and the variable wind shear method produce better estimates than the IEC standard. The mean power production was estimated at hub height (80 m above surface level) using anemometric data from the Mexican Wind Atlas and then compared with that calculated using the equivalent wind speed estimated from variable wind shear exponent and log-law model. No influence of the vertical wind speed variation within and on top (up to 117.5 m) of the surface boundary layer was found on the mean power production for a wind turbine with a diameter of 90 m and a hub height of 80 m.

Keywords

• Vertical wind profile
• Logarithmic profile
• Similarity theory
• Wind resource assessment
• Surface boundary layer
• Power law method