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Azimuth-inclination angles and snatch load on a tight mooring system
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.
2012 (English)In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 40, 40-49 p.Article in journal (Refereed) Published
Abstract [en]

A concept for wave energy conversion is being developed at the Swedish Center for Renewable Electric A Energy Conversion at the Angstrom Laboratory at Uppsala University, Sweden. This paper presents the results of offshore measurements where strain gauge sensors instrumented on the capsule of the WEC and a force transducer measuring line force from the floating buoy were used. A method for measurement and evaluation of the lateral force on the guiding system was developed. The experimental data allow us to define the inclination and azimuth angle between the generator and the floating buoy. The inclination angle is one of the key parameters for the design and the construction of the outer structure. It can be assumed that the inclination angle between the linear generator and the buoy with the stretched connection line did not exceed 8 at a sea state of 1.32 m waves. Snatch load between the buoy and the generator occur. This was obtained by a sudden jump of the inclination angle between the generator and the floating buoy. Moreover, the inclination and azimuth angle allow reproduction of the position of the floating buoy on the water surface.

Place, publisher, year, edition, pages
2012. Vol. 40, 40-49 p.
Keyword [en]
Tight mooring system, Offshore measurement, Strain gauge, Lateral force, Inclination and azimuth angles, Snatch load
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
URN: urn:nbn:se:uu:diva-171433DOI: 10.1016/j.oceaneng.2011.12.007ISI: 000300521300004OAI: oai:DiVA.org:uu-171433DiVA: diva2:510906
Available from: 2012-03-19 Created: 2012-03-19 Last updated: 2012-09-20Bibliographically approved
In thesis
1. Experimental results from the Lysekil Wave Power Research Site
Open this publication in new window or tab >>Experimental results from the Lysekil Wave Power Research Site
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents how experimental results, from wave power research performed offshore at the Lysekil research site, were obtained. The data were used to verify theoretical models as well as evaluate the feasibility of wave power as a future sustainable energy source.

The first experiments carried out at the research site was the measurement of the force in a line where one end was connected to a buoy with a diameter of 3 m and the other end to a set of springs with limited stroke length. The system is exposed to high peak forces compared to average forces. The maximum measured force in the line, when the buoy motion is limited by a stiff stopper rope is ten times the average force in that particular sea state.

The experiment performed on the first wave energy converter tested at the Lysekil Research Site is described. The infrastructure of the site is presented where the central connection point is the measuring station. The key finding is that it is possible to transform the motions of ocean waves into electrical energy and distribute it to land.

Many wave energy converters must be interconnected if large amounts of energy are to be harvested from the waves. The first submerged substation intended for aggregation of energy from wave power converters is described, with focus on the measurement and control system placed inside the substation. During this experiment period the generators were equipped with many different sensors; these measurements are explained in the thesis.

The system that aggregates power from the studied wave energy converter is regularly exposed to peak power of up to 20 times the maximum average output from the converter.

Vertical and horizontal movement of the buoy has been measured in different ways. The result is that the vertical displacement of the buoy can be measured with a simple accelerometer circuit but it is much more complicated to measure the horizontal displacement. A special method for measuring the horizontal displacement has been implemented by measuring the strain in the enclosure and the force in the line.

Abstract [sv]

Den här avhandlingen berättar om hur experimenten vid Lysekils forskningsområde för vågkraft har utförts. Insamlade mätdata har använts för att verifiera teoretiska samband som modulerats vid Elektricitetslära, Uppsala universitet. De teoretiska och praktiska resultaten har visat på att vågkraft har förutsättningarna att implementeras som en hållbar framtida energikälla. Intressanta mätmetoder har utvecklas och påfrestningarna  på utrustningin och dess samband med medel effekten har studerats.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 101 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 957
Wave power, Lysekil, Marine Substation, Offshore measurement, strain gauge, lateral force, Invlination and azimuth angles, Wave energy converter, Temperature measurements, Inverter, Energy, Control sustem, CompactRIO, Vågkraft, Mätteknik, Styrsystem, Lysekil
National Category
Marine Engineering Energy Systems Other Electrical Engineering, Electronic Engineering, Information Engineering Ocean and River Engineering Control Engineering
Research subject
Engineering Science
urn:nbn:se:uu:diva-179098 (URN)978-91-554-8433-0 (ISBN)
Public defence
2012-09-28, Polhem Å 10134, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
Lysekils projektet
Swedish Research Council, grant no. 621-2009-3417
Available from: 2012-09-05 Created: 2012-08-07 Last updated: 2013-01-22

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