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Progress of control system and measurement techniques for a 12 kW vertical axis wind turbine
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
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2008 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
2008. p. 186-190
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-97454OAI: oai:DiVA.org:uu-97454DiVA, id: diva2:172411
Conference
??
Available from: 2008-09-05 Created: 2008-09-05 Last updated: 2022-01-28Bibliographically approved
In thesis
1. Direct Driven Generators for Vertical Axis Wind Turbines
Open this publication in new window or tab >>Direct Driven Generators for Vertical Axis Wind Turbines
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wind power is a renewable energy source that is increasingly used all over the world. Most wind turbines have a horizontal axis of rotation but a few have a vertical axis of rotation. The concept presented in this thesis is a straight-bladed vertical axis wind turbine with a direct driven cable-wound permanent magnet synchronous generator. A comparison of the two different types of wind turbines, vertical axis wind turbines and horizontal axis wind turbines, have been performed considering several different aspects. However, the main focus in this thesis is on the generator.

Several generators have been modelled with a combined field and circuit model, which has been solved by using the finite element method. A 12 kW generator has been designed, which has a high overall efficiency and a high overload capability. The generator has been constructed at the department and was tested in the laboratory before being mounted in a vertical axis wind turbine. Results from experiments correspond well with results from simulations. The generator has been tested for different loading conditions and the harmonic content of the voltage has been analysed. A 12 kW vertical axis wind turbine was completed and tests have been performed. The results are encouraging and further studies on the prototype will be performed in the future.

The simulation method has been used to study electromagnetic losses in several generators. The comparison showed that the average losses should be considered when a variable speed generator for wind power is designed and it concluded that the design optimization process becomes a compromise between lowering the electromagnetic losses and having high overload capability.

When constructing a wind turbine, it is important to consider vibrations in the structure. Torsional vibrations in the drive shaft connecting the turbine to the rotor of the generator have been studied. It is shown that a direct driven generator is to prefer over an induction generator with a gearbox when torsional vibrations are concerned.

This thesis is based on eight papers all concerning vertical axis wind turbines with three of them focusing on the generator.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. p. 88
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 547
Keywords
synchronous generator, wind power, vertical axis wind turbine, simulations, experiments, finite element method
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:uu:diva-9210 (URN)978-91-554-7264-1 (ISBN)
Public defence
2008-09-26, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2008-09-05 Created: 2008-09-05 Last updated: 2022-01-28Bibliographically approved
2. Analytical Aerodynamic Simulation Tools for Vertical Axis Wind Turbines
Open this publication in new window or tab >>Analytical Aerodynamic Simulation Tools for Vertical Axis Wind Turbines
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wind power is a renewable energy source that is today the fastest growing solution to reduce CO2 emissions in the electric energy mix. Upwind horizontal axis wind turbine with three blades has been the preferred technical choice for more than two decades. This horizontal axis concept is today widely leading the market. The current PhD thesis will cover an alternative type of wind turbine with straight blades and rotating along the vertical axis. A brief overview of the main differences between the horizontal and vertical axis concept has been made. However the main focus of this thesis is the aerodynamics of the wind turbine blades.

Making aerodynamically efficient turbines starts with efficient blades. Making efficient blades requires a good understanding of the physical phenomena and effective simulations tools to model them. The specific aerodynamics for straight bladed vertical axis turbine flow are reviewed together with the standard aerodynamic simulations tools that have been used in the past by blade and rotor designer. A reasonably fast (regarding computer power) and accurate (regarding comparison with experimental results) simulation method was still lacking in the field prior to the current work. This thesis aims at designing such a method.

Analytical methods can be used to model complex flow if the geometry is simple. Therefore, a conformal mapping method is derived to transform any set of section into a set of standard circles. Then analytical procedures are generalized to simulate moving multibody sections in the complex vertical flows and forces experienced by the blades. Finally the fast semi analytical aerodynamic algorithm boosted by fast multipole methods to handle high number of vortices is coupled with a simple structural model of the rotor to investigate potential aeroelastic instabilities.

Together with these advanced simulation tools, a standard double multiple streamtube model has been developed and used to design several straight bladed rotor ranging from 2 kW to 20 kW.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. p. 100
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 774
Keywords
vertical axis turbine, vortex flows, conformal mapping, analytical aerodynamics, potential flows, fast multipole methods
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-132073 (URN)978-91-554-7913-8 (ISBN)
Public defence
2010-11-26, Häggsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Note
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 704Available from: 2010-11-04 Created: 2010-10-14 Last updated: 2011-03-22Bibliographically approved
3. Vertical Axis Wind Turbines: Electrical System and Experimental Results
Open this publication in new window or tab >>Vertical Axis Wind Turbines: Electrical System and Experimental Results
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The wind power research at the division of Electricity at Uppsala University is aimed towards increased understanding of vertical axis wind turbines. The considered type of wind turbine is an H-rotor with a directly driven synchronous generator operating at variable speed. The experimental work presented in this thesis comprises investigation of three vertical axis wind turbines of different design and size. The electrical, control and measurement systems for the first 12 kW wind turbine have been designed and implemented. The second was a 10 kW wind turbine adapted to a telecom application. Both the 12 kW and the 10 kW were operated against dump loads. The third turbine was a 200 kW grid-connected wind turbine, where control and measurement systems have been implemented.

Experimental results have shown that an all-electric control, substituting mechanical systems such as blade-pitch, is possible for this type of turbine. By controlling the rectified generator voltage, the rotational speed of the turbine is also controlled. An electrical start-up system has been built and verified. The power coefficient has been measured and the stall behaviour of this type of turbine has been examined. An optimum tip speed ratio control has been implemented and tested, with promising results. Use of the turbine to estimate the wind speed has been demonstrated. This has been used to get a faster regulation of the turbine compared to if an anemometer had been used.  

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. p. 77
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 981
Keywords
VAWT, H-rotor, start-up, all-electric control, Power Coefficient, stall, tip speed ratio, Renewable energy, Measurement systems, PM-generator
National Category
Energy Systems Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-182438 (URN)978-91-554-8496-5 (ISBN)
Public defence
2012-11-30, Room 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2012-11-07 Created: 2012-10-10 Last updated: 2018-05-30Bibliographically approved

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