برآورد و برون يابي ميانگين چگالي توان باد در راستاي قائم (مطالعه موردي: ايستگاه سينوپتيك شرق اصفهان)

Vertical Estimation and Extrapolation of Mean Wind Power Density (Case Study: East Isfahan Synoptic Station)

Understanding of the nature of considerable height variations of wind in the atmospheric boundary layer has an important role on wind turbines design. Since, generally aero generators hub are located at the upper level of the wind vector measurement standard level, to estimate the wind power potential at proposed level, the wind shear should be calculated. In this paper, some methods such as the suggested method by Justus and Mikhail (JM) and also the 1/7 power law has been examined to estimate and vertical extrapolation of mean wind power density. By the JM method the Weibull wind speed distribution parameters, have been vertical extrapolated. This technique is useful only for ensemble averages, and leads to large errors in individual cases. The 1/7 power law method usually gives conservative but reasonable estimates of wind power, except where the roughness of the site is large compared to the height of the reference level. To present the implementations of those methods, first the hybrid-Weibull distribution parameters of hourly averaged wind speeds of east Isfahan synoptic station, during the 1992-2005, have been calculated and then the mean wind power density at that site have been estimated. The 1/7 power law method, is the most convenient method to estimate mean wind power density. But this method doesnʹt always apply properly and is just a guide. Yet ·in the absence of actual measurement, the 1/7 power law is a reasonable, if sometimes conservative, approximation.