Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • 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
System Perspectives on Hydro-Kinetic Energy Conversion
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Free-flowing water currents such as tides and unregulated water courses could contribute to world electricity production given the emergence of robust technical solutions for extracting the energy. At Uppsala University, a concept for converting the energy in water currents to electricity using a vertical axis turbine with fixed blade-pitch and a direct-drive permanent magnet generator is studied.

Technological equipment for extracting energy from water currents can be studied at desktop to some extent, but physical realizations, first in a laboratory setting, and later in a natural aquatic setting, are necessary. For this reason, a laboratory generator has been constructed and evaluated, and an experimental setup comprising turbine, generator and control system has been constructed. The turbine and generator are to be deployed in the Dalälven River in Söderfors, and operated from an on-land control station. The author has worked with constructing and evaluating the low-speed laboratory generator, participated in the design and construction of the Söderfors generator, and designed and constructed the control system for Söderfors.

The generator design incorporates a low rotational speed, permanent magnets, and many poles, in order to adapt the generator to the nature of water currents. Simulations and experimental data for the laboratory prototype have been compared and show that the simulation tool used is adequate for design studies of this type of generator. The generator has also been shown to be able to operate with the intended turbine design and range of water velocities. The control system to be used in Söderfors has been tested in a laboratory environment. Simulations of the control system show that it should be able to operate the turbine and generator at the desired rotational speeds in water velocities up to about 1.8 m/s. Simulations of the system have also shown that maximizing system power output may not correspond with maximizing turbine power.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. , 65 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 976
Keyword [en]
tidal energy, permanent magnet, direct-drive, in-stream power converter, load control, vertical axis turbine, renewable energy, engineering science
National Category
Energy Systems Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-181555ISBN: 978-91-554-8479-8 (print)OAI: oai:DiVA.org:uu-181555DiVA: diva2:556765
Public defence
2012-11-09, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2012-10-18 Created: 2012-09-26 Last updated: 2013-01-23Bibliographically approved
List of papers
1. Experimental setup: Low speed permanent magnet generator for marine current power conversion
Open this publication in new window or tab >>Experimental setup: Low speed permanent magnet generator for marine current power conversion
2007 (English)In: Proceedings of the 26th International Conference on Offshore Mechanics and Arctic Engineering, Vol 5, 2007, 459-462 p.Conference paper, Published paper (Refereed)
Abstract [en]

Marine currents, e.g. tidal currents, ocean currents and unregulated water courses are characterized by a fairly steady or regular flow and pose a significant potential for electricity generation. An ongoing research project at Uppsala University is looking into an energy conversion system with a vertical axis turbine and a permanent magnet direct drive generator placed directly in the water flow, i.e. without using a dam. This choice of technology is intended to provide a simple and robust system with low maintenance needs and minimal environmental impact. During 2006 an experimental setup has been built. It consists of a frequency converter, a motor and a gearbox to drive the generator, the generator itself, and a resistive load to consume the generated power. The generator is two meters in diameter and is built on an elevated structure over the motor and gearbox. A stainless steel structure supports the cable wound stator. The permanent NdFeB magnets are fastened in milled grooves in the rotor. The experimental setup will be used for verification of a simulation and optimization program.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-96613 (URN)000249559500056 ()978-0-7918-4271-3 (ISBN)
Conference
26th International Conference on Offshore Mechanics and Arctic Engineering San Diego, CA, JUN 10-15, 2007
Available from: 2008-01-11 Created: 2008-01-11 Last updated: 2013-01-23Bibliographically approved
2. A direct drive generator for marine current energy conversion - first experimental results
Open this publication in new window or tab >>A direct drive generator for marine current energy conversion - first experimental results
2007 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Marine currents can be an effective source for renewable electric energy conversion. In this paper a direct drive permanent magnet synchronous generator capable of being connected to a vertical axis turbine for marine current energy conversion is presented. This 5 kVA, 120 pole, 10 rpm prototype generator was initially designed for ocean current speeds of 1.5 m/s using a finite element based electrical machine design software. Unlike most conventional generators this machine has a cable wound stator. To evaluate the electrical and mechanical performance characteristics of this machine, laboratory experiments are being carried out using a speedcontrolled motor drive system and resistive three phase loads. First measurements of voltage and current show good agreement between the modelled and built generator.

Place, publisher, year, edition, pages
Porto, Portugal: , 2007
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-133687 (URN)
Conference
European Wave and Tidal Energy Conference
Available from: 2010-11-15 Created: 2010-11-15 Last updated: 2016-04-11Bibliographically approved
3. A low-speed generator for energy conversion from marine currents: experimental validation of simulation
Open this publication in new window or tab >>A low-speed generator for energy conversion from marine currents: experimental validation of simulation
2008 (English)In: Proceedings of the Institution of mechanical engineers. Part A, journal of power and energy, ISSN 0957-6509, E-ISSN 2041-2967, Vol. 222, no 4, 381-388 p.Article in journal (Refereed) Published
Abstract [en]

A low-speed permanent magnet (PM) cable wound generator for electrical energy conversion from marine or tidal currents has been designed and constructed. A key feature of this variable speed direct drive generator is its capability to efficiently generate electricity from tidal currents with very low velocities, in the order of 1 m/s. In arriving at an appropriate design for the generator typical characteristics of tidal currents were considered. Using these characteristics as input, and accounting for the electromagnetic losses, detailed computer simulations using a finite-element method software were carried out to come up with the final design. Various parameters that can influence the generator design are presented. An experimental set-up has been constructed based on the above-mentioned design in order to study the electrical and mechanical performance of the generator through a variety of experiments. The power input for this set-up is a variable speed motor, capable of operating the generator at rotational speeds of 0–16 r/min, representing tidal currents with very low velocities. The generator presented in this paper may be beneficial for a better understanding of an appropriate design and layout of tidal energy conversion systems.

Keyword
finite-element method, marine currents, permanent magnet generator, tidal power
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-96614 (URN)10.1243/09576509JPE567 (DOI)000258167400005 ()
Available from: 2008-01-11 Created: 2008-01-11 Last updated: 2017-12-14Bibliographically approved
4. Matching a permanent magnet synchronous generator to a fixed pitch vertical axis turbine for marine current energy conversion
Open this publication in new window or tab >>Matching a permanent magnet synchronous generator to a fixed pitch vertical axis turbine for marine current energy conversion
Show others...
2009 (English)In: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 34, no 1, 24-31 p.Article in journal (Refereed) Published
Abstract [en]

Extracting energy from a free-flow marine current using a vertical axis fixed pitch turbine requires a generator that can handle varying speeds and loads, since such a turbine gives maximum power capture for a fixed tip speed ratio. A prototype of such a generator has been designed and constructed. In this paper, its variable speed and load operation is evaluated, both in terms of how the constructed generator performs in relation to simulations, and in terms of how the generator could perform with three different fixed pitch turbines. Measurements of root mean square (RMS) voltage and current differ 10% from simulations. Performance analysis with example turbines shows that the generator can match fixed tip speed ratio operation of several turbines for current speeds between 0.5 and 2.5 m/s.

Keyword
Fixed tip speed ratio operation, permanent magnet generators, tidal power generation, variable speed generator, vertical axis turbine
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-96617 (URN)10.1109/JOE.2008.2010658 (DOI)000264618000003 ()
Available from: 2008-01-11 Created: 2008-01-11 Last updated: 2017-12-14Bibliographically approved
5. A Permanent Magnet Generator for Energy Conversion from Marine Currents: No Load and Load Experiments
Open this publication in new window or tab >>A Permanent Magnet Generator for Energy Conversion from Marine Currents: No Load and Load Experiments
2012 (English)In: ISNR Renewable Energy, ISSN 2090-7451, Vol. 2012, 489379- p.Article in journal (Refereed) Published
Abstract [en]

This paper presents experiments and measurements on a low speed permanent magnet cable wound generator for marine currentenergy conversion.Measurements were made for no load and nominal load (4.44Ω/phase) conditions at nominal speed (10 rpm).For either load condition, the magnetic fields in the air gap were also measured. The measurements on the generator werecompared with the corresponding finite element method simulations used to design the machine. It is shown in the paper thatmeasurements and corresponding case simulations show good agreement. At nominal speed, the measured and simulated loadvoltages (nominal load) differ less than 1% for the rms values and less than 5% for peak values. At no load, measured and simulatedvoltages had larger differences, that is, <9% for rms values and <5% for peak values. Harmonic analyses of measured and simulatedphase voltages and currents show only the presence of third harmonics. The percentage of harmonics in the measured data wascomparable with the corresponding predictions of the simulations. The discussions and results presented in the paper could bebeneficial for future design of efficient and reliable marine current energy converter systems.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-176990 (URN)10.5402/2012/489379 (DOI)
Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2013-03-22Bibliographically approved
6. A Design Study of Marine Current Turbine-Generator Combinations
Open this publication in new window or tab >>A Design Study of Marine Current Turbine-Generator Combinations
2009 (English)In: Ocean, Offshore and Arctic Engineering (OMAE 2009), Honolulu, Hawaii., 2009Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Honolulu, Hawaii.: , 2009
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113287 (URN)
Conference
Ocean, Offshore and Arctic Engineering (OMAE 2009)
Available from: 2010-01-26 Created: 2010-01-26 Last updated: 2016-04-14
7.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
8.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
9.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
10.
The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.

Open Access in DiVA

fulltext(94620 kB)364 downloads
File information
File name FULLTEXT01.pdfFile size 94620 kBChecksum SHA-512
210a3fec11102cdad3d0a73fdffcf0c6f36e1b684b41ce20fe276d7a8c8793a2a93950edfc32a012b1a62a2d4a6dd1f051bff41d13e73cdb79fcbc1916eb6ab3
Type fulltextMimetype application/pdf