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Electrical damping of linear generator WECs - a review
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
(English)Article in journal (Refereed) Submitted
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:uu:diva-229193OAI: oai:DiVA.org:uu-229193DiVA: diva2:736113
Available from: 2014-08-05 Created: 2014-08-05 Last updated: 2014-12-02Bibliographically approved
In thesis
1. Offshore Marine Substation for Grid-Connection of Wave Power Farms: An Experimental Approach
Open this publication in new window or tab >>Offshore Marine Substation for Grid-Connection of Wave Power Farms: An Experimental Approach
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wave power is a renewable energy source with great potential, which is why there are more than a hundred ongoing wave power projects around the world. At the Division of Electricity, Uppsala University, a point-absorber type wave energy converter (WEC) has been proposed and developed. The WEC consists of a linear synchronous generator placed on the seabed, connected to a buoy floating on the surface. Power is absorbed by heave motion of the buoy, and converted into electric energy by the generator.

The point-absorber WEC must be physically much smaller than the wavelength of the incoming waves, and can therefore not be scaled to very high power levels. Instead, the total power output is boosted by increasing the number of WECs, connecting them in wave power farms. To transfer the electric energy to the grid, an intermediate marine substation is proposed, where an AC/DC/AC conversion step is performed.

Within this PhD-work, a full-scale offshore marine substation has been designed, constructed and experimentally evaluated. The substation is rated for grid-connection of seven WECs to the local 1kV-grid, and is placed on the seabed 3km off the coast at a depth of 25m. Various aspects of the substation design have been considered, including the mechanical and electrical systems, the WEC electrical interface, offshore operations and the automatic grid connection control system. A tap change circuit and different multilevel topologies have also been proposed.

This dissertation has an experimental approach, validating a major part of the work with lab results. The final substation electrical circuit has been tested at rated grid voltage with a fluctuating input power source. The efficiency has been measured and the implemented functions are verified. Offshore operations have been successfully carried out and offshore wave farm data is expected in the nearby future.  

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 93 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1166
Wave power, Offshore Marine Substation, Grid-Connection, Electrical Systems, Voltage-Source Inverter, On-load Tap Change, Cascaded H-bridge Multilevel Inverter
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
urn:nbn:se:uu:diva-229191 (URN)978-91-554-9004-1 (ISBN)
Public defence
2014-10-03, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2014-09-09 Created: 2014-08-05 Last updated: 2015-01-22

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