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Submerged Transmission in Wave Energy Converters: Full Scale In-Situ Experimental Measurements
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Different wave power technologies are in development around the world in different stages of prototype testing. So far only a few devices have been deployed offshore at full scale for extended periods of time. Little data is published about how these different devices perform.

This thesis presents results from experiments with the full-scale offshore wave energy converters at the Lysekil research site on the Swedish west coast. The theories, experiments, measurements, performance evaluations and developments of the submerged transmission in the direct driven permanent magnet linear generator are in focus. The reciprocating submerged transmission fulfills the purpose of transmitting the absorbed mechanical wave energy through the capsule wall into the generator, while preventing the seawater from entering the capsule and reducing the life time of the converter.

A measuring system with seven laser triangulation sensors has been developed to measure small relative displacements between piston rod and seal housing in the submerged transmission with excellent accuracy for the purpose of evaluating both functional behavior and successive wear in-situ. A method for calculating relative tilt angles, azimuth angles, differential tilt angles, and successive wear in the submerged transmission has been developed. Additional sensors systems have been installed in the converter enabling correlation and a thorough investigation into the operating conditions of the transmission and the converter. The thesis presents unique results from the measurements. A data acquisition system transmits the signals from the converter on the seabed to an onshore measuring station. Results are presented in time-, frequency- and the time-frequency domain.

The results have given important information for further development of the submerged transmission, which is important to the survivability of the system. The thesis describes the status of research, and is a step that may influence future designs of wave energy devices for reaching survivability and a cost-effective renewable energy system.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. , 214 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 961
Keyword [en]
Wave energy converter, direct drive, submerged transmission, piston rod, seal housing, sealing system, laser triangulation sensor, offshore measurements, relative displacement, vibrations, tilt angle, tilting, wear estimation.
National Category
Energy Systems Marine Engineering Ocean and River Engineering Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-179740ISBN: 978-91-554-8440-8 (print)OAI: oai:DiVA.org:uu-179740DiVA: diva2:545975
Public defence
2012-09-14, Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Projects
The Lysekil Wave Power Project
Note

Published is a preprint version of the full text and should be combined by the errata.

Available from: 2012-08-24 Created: 2012-08-21 Last updated: 2013-01-22Bibliographically approved
List of papers
1. Catch the wave to electricity: The Conversion of Wave Motions to Electricity Using a Grid-Oriented Approach
Open this publication in new window or tab >>Catch the wave to electricity: The Conversion of Wave Motions to Electricity Using a Grid-Oriented Approach
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2009 (English)In: IEEE Power and Energy Magazine, ISSN 1540-7977, Vol. 7, no 1, 50-54 p.Article in journal (Refereed) Published
Abstract [en]

The ocean are largely an untapped source of energy. However, compared to other energies, power fluctuations for ocean waves are small over longer periods of time. This paper present a grid-oriented approach to electricity production from ocean waves, utilizing a minimal amount of mechanical components.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-112949 (URN)10.1109/MPE.2008.930658 (DOI)000262015100004 ()
Available from: 2010-01-22 Created: 2010-01-22 Last updated: 2017-01-25Bibliographically approved
2. Wave Energy from the North Sea: Experiences from the Lysekil Research Site
Open this publication in new window or tab >>Wave Energy from the North Sea: Experiences from the Lysekil Research Site
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2008 (English)In: Surveys in geophysics, ISSN 0169-3298, E-ISSN 1573-0956, Vol. 29, no 3, 221-240 p.Article, review/survey (Refereed) Published
Abstract [en]

This paper provides a status update on the development of the Swedish wave energy research area located close to Lysekil on the Swedish West coast. The Lysekil project is run by the Centre for Renewable Electric Energy Conversion at Uppsala University. The project was started in 2004 and currently has permission to run until the end of 2013. During this time period 10 grid-connected wave energy converters, 30 buoys for studies on environmental impact, and a surveillance tower for monitoring the interaction between waves and converters will be installed and studied. To date the research area holds one complete wave energy converter connected to a measuring station on shore via a sea cable, a Wave Rider™ buoy for wave measurements, 25 buoys for studies on environmental impact, and a surveillance tower. The wave energy converter is based on a linear synchronous generator which is placed on the sea bed and driven by a heaving point absorber at the ocean surface. The converter is directly driven, i.e. it has no gearbox or other mechanical or hydraulic conversion system. This results in a simple and robust mechanical system, but also in a somewhat more complicated electrical system.

Keyword
Wave power, Renewable energy, Sea trial, Linear generator, Point absorber, Environmental impact
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-107215 (URN)10.1007/s10712-008-9047-x (DOI)000260967900002 ()
Available from: 2009-07-29 Created: 2009-07-29 Last updated: 2017-12-13Bibliographically approved
3. Experimental results from sea trials of an offshore wave energy system
Open this publication in new window or tab >>Experimental results from sea trials of an offshore wave energy system
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2007 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 3, 034105- p.Article in journal (Refereed) Published
Abstract [en]

A full-scale prototype of a wave power plant has been installed off the Swedish west coast and the overall wave energy converter concept has been verified. Initial results have been collected and significant insights discovered. Energy absorption dependency on load as well as output voltage and power is demonstrated. It is shown that great overload capability of the directly driven linear generator is critical, and indicated that, for resistive loads, optimal load does not vary with wave climate. Future grid supplying energy production would necessitate parks of wave power plants in order to reduce power fluctuations.

Keyword
High-current and high-voltage technology: power systems; power transmission lines and cables, Electric motors
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-95683 (URN)10.1063/1.2432168 (DOI)000243582400105 ()
Available from: 2007-03-23 Created: 2007-03-23 Last updated: 2017-12-14Bibliographically approved
4. Ocean wave energy absorption in response to wave period and amplitude: offshore experiments on a wave energy converter
Open this publication in new window or tab >>Ocean wave energy absorption in response to wave period and amplitude: offshore experiments on a wave energy converter
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2011 (English)In: IET Renewable Power Generation, ISSN 1752-1416, Vol. 5, no 6, 465-469 p.Article in journal (Refereed) Published
Abstract [en]

The ability of a wave energy converter to capture the energy of ocean waves has been studied in offshore experiments. This study covers 50 days during which the converter was subjected to ocean waves over a wide range of frequencies and amplitudes as well as three different electrical loads. The results present the wave energy converter??s energy absorption as a function of significant wave height, energy period and electrical load. It is shown that the power generated overall continues to increase with wave amplitude, whereas the relative absorption decreases towards the highest periods and amplitudes. The absorption reached a maximum of approximately 24% with the used combination of buoy, generator and electrical load. Absorption to cover for iron and mechanical losses has not been included. A brief study of the nature of the electromagnetic damping force has also been included in the study. The wave energy converter is of the technology that is being researched at Uppsala University and experimented on off the Swedish west coast at the Lysekil wave energy research site.

Place, publisher, year, edition, pages
IEEE Press, 2011
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-165034 (URN)10.1049/iet-rpg.2010.0124 (DOI)000303376900007 ()
Available from: 2012-01-02 Created: 2012-01-02 Last updated: 2013-05-17Bibliographically approved
5. Study of aWave Energy Converter Connected to a Nonlinear Load
Open this publication in new window or tab >>Study of aWave Energy Converter Connected to a Nonlinear Load
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2009 (English)In: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 34, no 2, 123-127 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents experimental results from a wave energy converter (WEC) that is based on a linear generator connected to a rectifier and filter components. The converter-filter system is installed onshore, while the linear wave generator operates offshore a few kilometers from the Swedish west coast. The power from the generator has been rectified with a diode bridge and then filtered using a capacitive filter. Performance of the whole conversion system was studied using resistive loads connected across the filter. The aim was to investigate the operational characteristics of the generator while supplying a nonlinear load. By changing the value of the resistive component of the load, the speed of the translator can be changed and so also the damping of the generator. The power absorbed by the generator was studied at different sea states as well. The observations presented in this paper could be beneficial for the design of efficient wave energy conversion systems.

Keyword
ocean waves
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-112947 (URN)10.1109/JOE.2009.2015021 (DOI)000266245600004 ()
Available from: 2010-01-22 Created: 2010-01-22 Last updated: 2017-12-12Bibliographically approved
6. Sensors and Measurements Inside the Second and Third Wave Energy Converter at the Lysekil Research Site.
Open this publication in new window or tab >>Sensors and Measurements Inside the Second and Third Wave Energy Converter at the Lysekil Research Site.
2011 (English)Conference paper, Published paper (Refereed)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-162252 (URN)
Conference
Conference
Available from: 2011-11-28 Created: 2011-11-28 Last updated: 2016-04-19
7. A Set-Up of 7 Laser Triangulation Sensors and a Draw-Wire Sensor for Measuring Relative Displacement of a Piston Rod Mechanical Lead-Through Transmission in an Offshore Wave Energy Converter on the Ocean Floor
Open this publication in new window or tab >>A Set-Up of 7 Laser Triangulation Sensors and a Draw-Wire Sensor for Measuring Relative Displacement of a Piston Rod Mechanical Lead-Through Transmission in an Offshore Wave Energy Converter on the Ocean Floor
2012 (English)In: ISRN Renewable Energy, ISSN 2090-746X, Vol. 2012, 746865- p.Article in journal (Refereed) Published
Abstract [en]

A concept for offshore wave energy conversion is being developed at the Swedish Centre for Renewable Electric Energy Conversion at Uppsala University in Sweden. The wave energy converter (WEC) in focus contains a piston rod mechanical lead-through transmission for transmitting the absorbed mechanical wave energy through the generator capsule wall while preventing seawater from entering the capsule. A set-up of 7 laser triangulation sensors has been installed inside the WEC to measure relative displacement of the piston rod and its corresponding seal housing. A draw-wire sensor has also been set up to measure translator position and the axial displacement of the piston rod. The paper gives a brief introduction to the Lysekil research site, the WEC concept, and the direct drive of WEC prototype L2. A model of operation for the piston rod mechanical lead-through transmission is given. The paper presents sensor choice, configuration, adaptation, mounting, and measurement system calibration along with a description of the data acquisition system. Results from 60 s measurements of nominal operation two months apart with centered moving averages are presented. Uncertainty and error estimations with statistical analyses and signal-to-noise ratios are presented. Conclusions are drawn on the relative motions of the piston rod and the seal housing under normal operating conditions, and an assessment of the applicability of the measurement system is made.

Place, publisher, year, edition, pages
New York: Hindawi Publishing Corporation, 2012
Keyword
Wave energy, Laser, Sensor, Triangulation, Draw-wire, Piston rod, Transmission, Submerged, Offshore, Measurements, Mechanical lead-through.
National Category
Applied Mechanics Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-179099 (URN)10.5402/2012/746865 (DOI)
Projects
The Lysekil Wave Power Project
Available from: 2012-08-07 Created: 2012-08-07 Last updated: 2012-09-20Bibliographically approved
8. Time Series-, Time-Frequency- and Spectral Analyses of Sensor Measurements in an Offshore Wave Energy Converter Based on Linear Generator Technology
Open this publication in new window or tab >>Time Series-, Time-Frequency- and Spectral Analyses of Sensor Measurements in an Offshore Wave Energy Converter Based on Linear Generator Technology
(English)In: Energy and Power Engineering, ISSN 1949-243XArticle in journal (Other academic) Submitted
Abstract [en]

The second wave energy converter (WEC) prototype launched at the Lysekil research site on the Swedish west coast in March 2009 contained a number of sensor systems for measuring the mechanical performance of the WEC and mechanical subsystems within the WEC. Measurements were carried out during the first experimental period starting from May 15th and ending on September 23rd. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Two measurement periods separated by 2.5 month are presented to be able to draw conclusion on what happens with time. Comparisons and correlations are made between different sensors measuring simultaneously, especially for the laser triangulation sensor measurements. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period in August. Vibrations frequencies due to wear is possible from comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.

Keyword
wave energy converter, linear generator, sensor measurements, spectral analysis, cogging, filtering, laser triangulation sensor, draw-wire sensor, force transducer, strain gauges, search coils, power generation
National Category
Ocean and River Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-179733 (URN)
Projects
The Lysekil Wave Power Project
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2012-09-07Bibliographically approved
9. Measurements of Relative Displacement and Tilting of a Piston Rod Transmission in a Submerged Linear Wave Energy Converter Operating with End Stop Impact
Open this publication in new window or tab >>Measurements of Relative Displacement and Tilting of a Piston Rod Transmission in a Submerged Linear Wave Energy Converter Operating with End Stop Impact
(English)In: Journal of Offshore Mechanics and Arctic Engineering-Transactions of The Asme, ISSN 0892-7219, E-ISSN 1528-896XArticle in journal (Other academic) Submitted
Abstract [en]

A type of piston rod mechanical-lead through transmission has been designed and implemented inside the two first wave energy converter (WEC) prototypes at the Lysekil wave energy research site on the Swedish west cost. The transmission constitutes a direct drive which transfers the mechanical force, absorbed from the waves by a heaving surface-floating buoy, through an encapsulation and into a permanent magnet linear generator bolted to a foundation on the seabed, while sealing off the corrosive seawater. A set-up of 7 laser triangulation sensors have been installed in the second wave energy converter prototype to measure the relative displacement of the piston rod and seal housing in the mechanical lead-through in-situ. This paper presents measurements from full scale operation in two different sea states with end stop impact. Since wear is a successive process stretched out over time measurements have been performed for both sea states with 2.5 month separation. The experimental set-up and sensors are described. Equations for calculating tilt angles and azimuth angles for the piston rod are presented. Results from structure mechanical FEM simulations performed on the wave energy converter structure at end stop impact is also presented. The laser sensor measurements of the relative sideway displacements are correlated with measurements of the translator position and piston rod stroke length performed with a draw wire sensor. A force transducer is used for measuring the force in the buoy line to better understand the variations in motion due to changes in the buoy line axial force. Tilt angles and azimuth angles are presented for a wave period in each measurement period. The results are discussed and conclusions drawn with specific emphasis on the effects of the end stop impacts and wear on the funnel. The successive wear in the buoy line guiding system results in a 6 fold increase in relative tilt angle of the piston rod over a period of 2.5 months. A corresponding increase in motion is also seen for the seal housing, but to a lesser extent, indicating wear on the dynamic sealing system housed inside. The measurements of the relative displacement of the piston rod and seal housing are intended for further research.

Keyword
wave energy converter, linear generator, direct drive, submerged transmission, piston rod, laser triangulation sensor, draw-wire sensor, force transducer, FEM simulation, relative displacement measurement, end stop impact
National Category
Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-179735 (URN)
Projects
The Lysekil Wave Power Project
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2017-12-07Bibliographically approved
10. In-Situ Measurements of Relative Displacement between Piston Rod and Seal Housing with Estimations of Wear on a Sealing System in a Submerged Transmission of an Offshore Underwater Wave Energy Converter
Open this publication in new window or tab >>In-Situ Measurements of Relative Displacement between Piston Rod and Seal Housing with Estimations of Wear on a Sealing System in a Submerged Transmission of an Offshore Underwater Wave Energy Converter
(English)In: Journal of Renewable and Sustainable Energy, ISSN 1941-7012Article in journal (Other academic) Submitted
Abstract [en]

A type of submerged piston rod mechanical lead-through transmission has been designed and implemented inside the two first full scale wave energy converter (WEC) prototypes at the Lysekil wave energy research site on the Swedish west cost. The transmission constitutes a direct drive which transfers the mechanical force, absorbed from the waves by a heaving surface-floating buoy, through an encapsulation and into a permanent magnet linear generator bolted to a foundation on the seabed, while sealing off the corrosive seawater. A set-up of 7 laser triangulation sensors has been installed in the second wave energy converter prototype to measure the relative displacement of the piston rod and the seal housing in-situ. This paper focus on investigating the relative tilt angles of both objects, the differential tilt angle between the piston rod and the seal housing and how they move in the time and space as they tilt with the ocean waves. Estimations on wear of the sealing components in the dynamic sealing system are made. The measurements are performed for two sea states with 2.5 month separation. The paper describes the experimental set-up and the sensor measuring systems. Equations for calculating the relative differential tilt angle between piston rod and seal housing are presented. The calculated differential tilt angle is correlated with measurements of the piston stroke length and translator position performed with the draw-wire sensor. Tilt angles, azimuth angles and differential tilt angles are presented for one wave period in each measurement period. The wear is estimated by calculating the relative change in traversed clearance gap by the piston rod across the interface inside the seal housing. Results show the expected differential tilt angle early in the experiment. A substantial increase in differential tilt angle developed over 3 months time as a consequence of large wear between buoy line and guiding funnel causing a large tilt angle on the piston rod and unintentionally large normal forces between piston rod and the dynamic sealing system inside the seal housing. The results indicate the need of a more flexible mechanical lead-through design, which is presented at the end of the paper. The results are discussed and conclusions are drawn with specific emphasis on improving the sealing system with stronger guide elements and the patented mechanical lead-through design.

Keyword
wave energy converter; linear generator; direct drive; piston rod; seal housing; mechanical lead-through; submerged transmission; relative displacement measurement; laser triangulation sensor; tilting; tilt angle; azimuth angle; estimation of wear; sealing component.
National Category
Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-179737 (URN)
Projects
The Lysekil Wave Power Project
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2012-09-07Bibliographically approved
11. Temperature measurements in a linear generator and marine substation for wave power
Open this publication in new window or tab >>Temperature measurements in a linear generator and marine substation for wave power
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2012 (English)In: Journal of Offshore Mechanics and Arctic Engineering-Transactions of The Asme, ISSN 0892-7219, E-ISSN 1528-896X, Vol. 134, no 2, 021901- p.Article in journal (Refereed) Published
Abstract [en]

This paper analyzes temperature measurements acquired in the offshore operation of a wave energy converter array. The three directly driven wave energy converters have linear generators and are connected to a marine substation placed on the seabed. The highly irregular individual linear generator voltages are rectified and added on a common dc-link and inverted to 50 Hz to facilitate future grid-connection. The electrical power is transmitted to shore and converted to heat in a measuring station. The first results of temperature measurements on substation components and on the stator of one of the linear generators are presented based on operation in linear and in nonlinear damping. The results indicate that there might be some convective heat transfer in the substation vessel. If high power levels are extracted from the waves, this has to be considered when placing components in the substation vessel in order to avoid heating from neighboring components. The results also indicate that the temperature increase in the linear generator stator is very small. Failure due to excessive heating of the stator winding polyvinyl chloride cable insulation is unlikely to occur even in very energetic sea states. Should this conclusion be incorrect, the thermal conductivity between the stator and the hull of the wave energy converter could be enhanced. Another suggested alteration is to lower the resistive losses by reducing the linear generator current density.

Keyword
convection, linear machines, machine insulation, machine windings, offshore installations, power convertors, stators, substations, temperature measurement, wave power generation
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-140113 (URN)10.1115/1.4004629 (DOI)000308596500021 ()
Available from: 2011-01-04 Created: 2011-01-04 Last updated: 2017-12-11Bibliographically approved
12. Wave Buoy and Translator Motions - On-Site Measurements and Simulations
Open this publication in new window or tab >>Wave Buoy and Translator Motions - On-Site Measurements and Simulations
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2011 (English)In: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 36, no 3, 377-385 p.Article in journal (Refereed) Published
Abstract [en]

For a complete understanding of a wave energy conversion device, it is important to know how the proposed device moves in the water, how this motion can be measured, and to what extent the motion can be predicted or simulated. The magnitude and character of the motion has impacts on engineering issues and optimization of control parameters, as well as the theoretical understanding of the system. This paper presents real sea measurements of buoy motion and translator motion fora wave energy system using a linear generator. Buoy motion has been measured using two different systems: a land-based optical system and a buoy-based accelerometer system. The data have been compared to simulations from a Simulink model for the entire system. The two real sea measurements of buoy motion have been found to correlate well in the vertical direction, where the measured range of motion and the standard deviation of the position distributions differed with 3 and 4 cm, respectively. The difference in the horizontal direction ismore substantial. The main reason for this is that the buoy rotation about its axis of symmetry was not measured. However, used together the two systems give a good understanding of buoy motion. In a first comparison, the simulations show good agreement with the measured motion for both translator and buoy.

Keyword
Accelerometers, energy conversion, experimental results, image motion analysis, oceanic engineering, marine technology, wave power
National Category
Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-160072 (URN)10.1109/JOE.2011.2136970 (DOI)
Available from: 2012-01-09 Created: 2011-10-14 Last updated: 2017-12-08Bibliographically approved
13. Description of a torus shaped buoy for wave energy point absorber
Open this publication in new window or tab >>Description of a torus shaped buoy for wave energy point absorber
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2010 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-142504 (URN)
Conference
Renewable Energy 2010, 27 June - 2 July, Pacifico Yokohama, Japan
Available from: 2011-01-14 Created: 2011-01-14 Last updated: 2015-01-07Bibliographically approved
14. Lysekil Research Site, Sweden: A status update
Open this publication in new window or tab >>Lysekil Research Site, Sweden: A status update
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2011 (English)In: 9th European Wave and Tidal Energy Conference, Southampton, UK, 2011, 2011Conference paper, Published paper (Refereed)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-160039 (URN)
Conference
9th European Wave and Tidal Energy Conference, Southampton, UK, 5-9 September 2011
Available from: 2011-10-13 Created: 2011-10-13 Last updated: 2017-01-25
15. A wave power unit
Open this publication in new window or tab >>A wave power unit
2010 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

The invention relates to a wave-power unit for the production of electric power. It comprises a floating body arranged for floating on the sea and an electric linear generator having a stator and a translator reciprocating along a center axis. The stator is arranged to be anchored in the bed of the sea and the translator is connected tothe floating body by connection means. According to the invention the generator is enclosed in a watertight encapsulation having an upper end wall with an opening through which the connection means extends. The opening has a seal that seals against the connection means. The seal is flexibly mounted. The invention also relates to the use of the wave-power unit and to a method for producing electric power.

Keyword
wave power, submerged, transmission, flexible unit, compensator, seal housing, piston rod
National Category
Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-179738 (URN)
Patent
World Intellectual Property Organization WO2010/024740 A1 (2010-03-04)
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2012-08-31Bibliographically approved
16. A wave power unit, a buoy, use of a wave power unit and a method for producing electric energy
Open this publication in new window or tab >>A wave power unit, a buoy, use of a wave power unit and a method for producing electric energy
2008 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

The invention relates to a wave power unit with a buoy, adapted to float on a water surface. An electric generator is connected to the buoy through connection means. According to the invention the buoy when floating on a water surface and when seen in a direction perpendicular to the water surface has the shape of a closed loop enclosing an inner opening. The invention also relates to a buoy for a wave power unit, which buoy has the corresponding features as above. Further, the invention relates to the use of the invented wave power unit and to a method for producing electric energy with the invented wave power unit.    

National Category
Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-179739 (URN)
Patent
World Intellectual Property Organization WO2008/130295 A1 (2008-10-30)
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2012-09-07Bibliographically approved

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