An Analysis of Wind Speed Distribution at Thasala, Nakhon Si Thammarat, Thailand

The main objective of this paper was to analyze the statistical wind data obtained from measurements for the 12 months period of January to December 2008 at Thasala district in Nakhon Si Thammarat province, southern Thailand. The wind speed at heights of 20 m, 30 m, and 40 m above ground level were measured using 3-cup anemometers attached to booms on a 45 m lattice met tower. The recording interval was 10 min. The statistical wind data set was analyzed using Weibull distributions in order to investigate the Weibull shape and scale parameters. The Weibull parameters obtained from WAsP 9.0 analysis as well as from the probability density function and cumulative distribution function of graphical methods were compared and the mean bias error between the methods was determined. Results showed that the monthly Weibull shape parameter was in the range of 1.1-2.8, while the monthly Weibull scale parameter was in the range of 2.27-5.94 m/s corresponding to monthly mean wind speeds in the range of 2.2-9.4 m/s. The mean wind speeds at 20 m, 30 m, and 40 m determined by WAsP 9.0 from the observational data were in the range of 2.4-7.8 m/s, 2.7-8.3 m/s, and 3.1-8.8 m/s respectively. The monthly power density was in the range of 5.8-480.3 W/m2 corresponding to the wind power class ranging from class 1- to class 4+. Results showed that strong and sufficient winds for power generation occurred during the months of January to July and in the month of October.