Abstract

The scope of this thesis is the study and the measurement of the power curve of a locally manufactured small wind turbine, as well as the optimization of the production cost for the installation of small wind turbines for low cost and appropriate technology applications. In this framework, measurements are conducted for the determination of the power curve in a wind tunnel and in a test site at the roof of the Electrical and Computer Engineering department of the National Technical University of Athens.

Initially, the basic characteristics of small wind turbines are mentioned and comprehensive analysis is performed for their installation in the urban environment, which is followed by a study of the appropriateness of the position of a small wind turbine with nominal power 850W (2.4m rotor diameter) which is examined in the test site of the building. An analysis of the furling mechanism follows, as the primary method of passive speed control of these wind turbines, and its correlation to the diversion load control that connects to electrical output of the wind turbine to the grid-tie inverter.

Additionally, existent tests which take place for the certification of small wind turbines are described and the specifications of the IEC Standard 61400-12 for power performance measurements are mentioned in a comprehensive reference.

Furthermore, the measurement, in an wind tunnel, of the power curve of a small wind turbine with rated power 350W (1.2m rotor diameter) follows and the design as well as the development of an acquisition system for the power curve measurement of a small wind turbine with rated power 850W (2.4m rotor diameter), in the NTUA test site is described. Also, results are presented for the produced power, the estimated annual energy production and the aerodynamic power coefficient.

Finally, an optimization of the production cost for six locally manufactured small wind turbines is performed, according to the characteristics of the location in which they will be installed. Results describe the most financially appropriate hub height of a wind turbine and the most financially appropriate length of its rotor blades. Also, the depreciation time of such an investment is presented for a grid connected system in Greece.

Keywords: small wind turbines, appropriate technology, low cost applications, furling control, power curve measurement, aerodynamic power coefficient, wind tunnel, acquisition system, production cost, rural electrification

Author: Thanos Gravas

Responsible PhD: Kostas Latoufis / latoufis@power.ece.ntua.gr

Supervising Professor: Nikos Hatziargyriou / nh@power.ece.ntua.gr

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