uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Time stepping finite element analysis of variable speed synchronous generator with rectifier
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Division for Electricity and Lightning Research.
Show others and affiliations
2006 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 83, no 4, 371-386 p.Article in journal (Refereed) Published
Abstract [en]

Several applications for renewable energy conversion make use of variable speed generators. A conversion from variable frequency to grid frequency is therefore essential. One part of the converter is a rectifier. A rectifier model is presented, which is integrated in a time stepping finite element simulation environment where the generator and circuit equations are solved simultaneously. The model handles bidirectional alternator speeds as the application is a linear generator for ocean wave energy conversion. The rectifier model is extended with a load model, consisting of R, L and E, and simulations show what impact the rectifier has on the generator’s behaviour.

Place, publisher, year, edition, pages
2006. Vol. 83, no 4, 371-386 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-95678DOI: 10.1016/j.apenergy.2004.10.016OAI: oai:DiVA.org:uu-95678DiVA: diva2:169987
Available from: 2007-03-23 Created: 2007-03-23 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Modelling and Experimental Verification of Direct Drive Wave Energy Conversion: Buoy-Generator Dynamics
Open this publication in new window or tab >>Modelling and Experimental Verification of Direct Drive Wave Energy Conversion: Buoy-Generator Dynamics
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is focused on development of models and modelling of a wave energy converter in operation. Through the thesis linear potential wave theory has been used to describe the wave-buoy interaction. The differences lie in the generator models, in the simplest model the generator is a mechanical damper characterized by a damping factor. In the most advanced generator model the magnetic fields is calculated the by a FE-method, which gives detailed description of the electric properties and the effect it has on the buoy dynamics. Moreover, an equivalent circuit description of the generator has been tested. It has the same accuracy as the field based model but with a strongly enhanced CPU time. All models are verified against full scale experiments. The models are intended to be used for design of the next generation wave energy converters. Further, the developed models have also been used to study what effect buoy geometry and generator damping have on the ability to energy absorption.

In the spring 2006 a full scale wave energy converter was installed at the west coast of Sweden. It was in operation and collected data during three months. During that period the load resistance was varied in order to study the effect on the energy absorption. These collected data was then used in the verification of the developed models.

In the year 2002 a wave energy project started at Uppsala University; this work is a part of that larger project which intendeds to develop a viable wave energy conversion concept.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 76 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 287
Keyword
Engineering physics, Wave energy, Potential wave theory, Linear generator, Simulations, Experiments, Point absorber, FEM, Equivalent circuit theory, Teknisk fysik
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-7785 (URN)978-91-554-6850-7 (ISBN)
Public defence
2007-04-13, Polhemsalen, Ångströmlaboratoriet, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2007-03-23 Created: 2007-03-23 Last updated: 2010-11-10Bibliographically approved
2. Electric Energy Conversion Systems: Wave Energy and Hydropower
Open this publication in new window or tab >>Electric Energy Conversion Systems: Wave Energy and Hydropower
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electric energy conversion is an important issue in today's society as our daily lives largely depend on the supplies of energy. Two energy sources are studied for conversion in the present thesis, ocean waves and hydropower. The work focuses on the generator and the transmission of its output to the electric grid.

Different approaches have been used, over the years, to convert the energy in ocean waves, and the method presently used is based on a point absorber (buoy) directly coupled to a linear generator on the seabed. A varying alternating voltage is induced with such configuration, where both the amplitude and the frequency changes continuously. The target is to connect several units in a farm, and thereby decrease the fluctuations in power production. This is shown to be possible to accomplish with a rectifier connected to each generator. Transmission systems can be designed with converters and transformers to connect the farm to the electric grid onshore. Several aspects of the concept are considered as well as interconnection issues. Analytical calculations verified by finite element simulations and measured data are used to model the behaviour of a linear generator. A series expanded expression for the ideal no-load flux and EMF (electromotive force) is derived, which can be developed into an analytical transmission design tool.

Hydropower has been used for more than a century. Today many of the stations from the mid 1900's are up for refurbishment. Studies with finite element calculations show that a higher electric efficiency can be obtained with a high voltage cable wound generator.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 59 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 202
Keyword
Engineering physics, Ocean wave power, renewable energy, linear generator, farm simulation, Teknisk fysik
Identifiers
urn:nbn:se:uu:diva-7081 (URN)91-554-6617-6 (ISBN)
Public defence
2006-09-22, Siegbahnsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15
Opponent
Supervisors
Available from: 2006-09-01 Created: 2006-09-01 Last updated: 2013-07-31Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Wolfbrandt, ArneLeijon, Mats

Search in DiVA

By author/editor
Wolfbrandt, ArneLeijon, Mats
By organisation
Division for Electricity and Lightning Research
In the same journal
Applied Energy
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 570 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf