Συμβολή στη μελέτη των χαρακτηριστικών του διανυσματικού ανέμου στη Βόρεια Ελλάδα με στόχο την εφαρμογή προγραμμάτων αιολικής ενέργειας.

Περίληψη

The overall objective of this research thesis is to provide a scientific methodology for the performance of a feasibility study concerning the implementation of wind energy programs, with the purpose of converting energy from the wind to electric power, with the use of wind turbines. To meet this objective, wind speed and wind direction data from six meteorological stations of the northern part of the Greek National Meteorological Service network are used, in order to predict and calculate wind potential that can be extracted through the lower part of the boundary layer. The first step of this research is to study the climatological wind conditions at the six meteorological stations in Northern Greece. This initial study of the wind regime will provide the general wind characteristics, like mean wind speed and distribution of wind to the sixteen wind directions, during the four seasons of the year, which are important elements in deciding, if a site is suitable for wind farm settlement. The second step in computing the wind potential at a site, is the use of theoretical distributions, in order to characterize the behavior of the actual wind. Different theoretical distributions, such as the Weibull, Raylight, Gumbel, and the Log-normal, are evaluated. The Gumbel and the two parametric Weibull distributions are proven to characterize in a best way the actual wind. Different methods of computing the scale and the shape parameters of the Weibull distribution are also evaluated. The next step is to study the extrapolation of the wind from the anemometer level to different heights, which represent the hub height of existing wind turbines. The power law, which is a generalization of the Monin-Obukov similarity theory equations, under different atmospheric stability and roughness length conditions, is utilized. The power law is essential for extrapolating the Weibull distribution, which is proven to give the best theoretical fit to the actual data, to hub level. The use of the theoretical data that are created to different heights is essential, in order to minimize the influence of both random errors in wind measurements and the broader vicinity of the generator site to the calculation of the wind potential. Finally, an additional study on the wind regime is implemented, concerning the behavior of the maximum wind speeds and particularly the gust winds. Using better resolution measurements, a relationship between the gust winds and the hourly (daily) mean wind speeds is established. This relationship is very useful, in order to assess and forecast the hazards that extreme wind conditions poses to the wind generator.