WIND RESOURCE ASSESSMENT USINGTHREE PARAMETER MIXTURE WEIBULL DISTRIBUTION

Abstract

For offshore wind energy assessment it is essential to appropriately model and describe wind climate. Rayleigh and Weibull distributions are widely suggested for offshore wind speed modelling. The use of these distributions is theoretically consistent, but in places where calm wind speed is experienced, they are often proved to be inadequate. In these cases mixture distributions are used. In this paper we have proposed a mixture of three parameter Weibull distribution. The three parameter mixture Weibull distribution is used to calculate the Capacity factor available in the wind. Parameter estimation is very much critical for the application of statistical model and is a challenging problem precisely for a Weibull distribution with more than two parameters. A study on estimation of parameters using maximum likelihood method, Least square method, Energy pattern factor method and Moment method is discussed. Our study shows that the PDF and CDF of the three parameter mixture Weibull distribution generated by the estimated parameters using various methods gave a good fit to the observed wind speed frequency at the particular site, ie, the bimodal peak.