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Marine Current Energy Conversion
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Marine currents, i.e. water currents in oceans and rivers, constitute a large renewable energy resource. This thesis presents research done on the subject of marine current energy conversion in a broad sense.

A review of the tidal energy resource in Norway is presented, with the conclusion that tidal currents ought to be an interesting option for Norway in terms of renewable energy.

The design of marine current energy conversion devices is studied. It is argued that turbine and generator cannot be seen as separate entities but must be designed and optimised as a unit for a given conversion site. The influence of support structure for the turbine blades on the efficiency of the turbine is studied, leading to the conclusion that it may be better to optimise a turbine for a lower flow speed than the maximum speed at the site.

The construction and development of a marine current energy experimental station in the River Dalälven at Söderfors is reported. Measurements of the turbine's power coefficient indicate that it is possible to build efficient turbines for low flow speeds. Experiments at the site are used for investigations into different load control methods and for validation of a numerical model of the energy conversion system and the model's ability to predict system behaviour in response to step changes in operational tip speed ratio.

A method for wake measurements is evaluated and found to be useful within certain limits. Simple models for turbine runaway behaviour are derived, of which one is shown by comparison with experimental results to predict the behaviour well.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. , 66 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1353
Keyword [en]
marine current energy, renewable energy, turbine, energy conversion, wake, Söderfors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-280763ISBN: 978-91-554-9510-7 (print)OAI: oai:DiVA.org:uu-280763DiVA: diva2:911949
Public defence
2016-05-04, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2016-04-08 Created: 2016-03-15 Last updated: 2016-04-12
List of papers
1. Validation of a Coupled Electrical and Hydrodynamic Simulation Model For Vertical Axis Marine Current Energy Converters
Open this publication in new window or tab >>Validation of a Coupled Electrical and Hydrodynamic Simulation Model For Vertical Axis Marine Current Energy Converters
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

This paper validates a simulation model for a Vertical Axis Turbine connected to a Permanent Magnet Synchronous Generator in a direct drive configuration. The simulated system consists of the electrical system and a hydrodynamicvortex model for the turbine. Experiments of no load operation were conducted to calibratethe drag losses of the turbine. Simulations were able to predict the behaviour of a stepresponse for a change in Tip Speed Ratio (TSR) when the turbine was operated close to optimal TSR. The turbine start position could be changed to view the influence of changed relative position of the turbine to the water flow in the step response.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-267944 (URN)
Funder
StandUpÅForsk (Ångpanneföreningen's Foundation for Research and Development)Vattenfall ABSwedish Research CouncilSwedish Energy AgencyVattenfall AB
Note

Funders: J Gust Richert, Bixia Miljöfond

Available from: 2015-12-10 Created: 2015-11-30 Last updated: 2016-04-12Bibliographically approved
2. Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter
Open this publication in new window or tab >>Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter
2015 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 8, no 5, 4572-4586 p.Article in journal (Refereed) Published
Abstract [en]

This paper investigates three load control methods for a  marine current energy converter using a vertical axis current  turbine (VACT) mounted on a permanent magnet synchronous generator  (PMSG). The three cases are; a fixed AC load, a fixed pulse width  modulated (PWM) DC load and DC bus voltage control of a DC  load. Experimental results show that the DC bus voltage control  reduces the variations of rotational speed by a factor of 3.5 at the cost  of slightly increased losses in the generator and transmission lines.  For all three cases, the tip speed ratio   can be kept close to  the expected    . The power coefficient is estimated to be  0.36 at    ; however, for all three cases, the average  extracted power was about  \%. A maximum power point  tracking (MPPT) system, with or without water velocity measurement,  could increase the average extracted power.

Keyword
Load Control, Vertical axis turbine, permanent magnet generator
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-244939 (URN)10.3390/en8054572 (DOI)000356879600064 ()
Funder
StandUpÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research CouncilSwedish Energy AgencyVattenfall AB
Note

Funders: J Gust Richert, Bixia Miljöfond

Available from: 2015-02-23 Created: 2015-02-23 Last updated: 2017-12-04Bibliographically approved
3. A parameter study of the influence of struts on the performance of a vertical-axis marine current turbine.
Open this publication in new window or tab >>A parameter study of the influence of struts on the performance of a vertical-axis marine current turbine.
2009 (English)Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Uppsala, Sweden: , 2009
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113279 (URN)
Conference
EWTEC09,
Available from: 2010-01-26 Created: 2010-01-26 Last updated: 2016-04-14Bibliographically approved
4. A review of the tidal current energy resource in Norway
Open this publication in new window or tab >>A review of the tidal current energy resource in Norway
2009 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 13, no 8, 1898-1909 p.Article, review/survey (Refereed) Published
Abstract [en]

As interest in renewable energy sources is steadily on the rise, tidal current energy is receiving more and more attention from politicans, industrialists, and academics. In this article, the conditions for and potential of tidal currents as an energy resource in Norway are reviewed. There having been a relatively small amount of academic work published in this particular field, closely related topics such as the energy situation in Norway in general, the oceanography of the Norwegian coastline, and numerical models of tidal currents in Norwegian waters are also examined. Two published tidal energy resource assessments are reviewed and compared to a desktop study made specifically for this review based on available data in pilot books. The argument is made that tidal current energy ought to be an important option for Norway in terms of renewable energy.

Place, publisher, year, edition, pages
Elsevier, 2009
Keyword
Tidal current, Renewable energy, Ocean energy
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Oceanography, Hydrology, Water Resources Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-113144 (URN)10.1016/j.rser.2009.01.026 (DOI)000269135000012 ()1364-0321 (ISBN)
Available from: 2010-10-28 Created: 2010-01-25 Last updated: 2017-12-12Bibliographically approved
5. Studying the Wake of a Marine Current Turbine Using an Acoustic Doppler Current Profiler
Open this publication in new window or tab >>Studying the Wake of a Marine Current Turbine Using an Acoustic Doppler Current Profiler
2015 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Wake characteristics of marine current turbines are of significant importance to the development of the marine current power source. Turbine wake recovery determines spacing of turbines in arrays, and environmental impact on e.g. the seabed is heavily influenced by wake behaviour. The majority of previous studies on wakes has been performed on flow-aligned (horizontal) axis turbines and mainly carried out as scale model experiments or numerical simulations.

This paper describes the performance of wake measurements at the Söderfors test site, where an experimental marine current power station is operated in a river. The turbine is of the cross-flow (vertical) axis type, and the measurements are performed using an Acoustic Doppler Current Profiler (ADCP) towed on the surface by a boat. Positioning data is taken from a high-accuracy Global Navigation Satellite System. The paper discusses various aspects of the methodology employed and provides examples of taken measurements.

National Category
Energy Engineering Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-265358 (URN)
Conference
11th European Wave and Tidal Energy Conference, EWTEC15, 6-11 September 2015, Nantes, France
Available from: 2015-10-27 Created: 2015-10-27 Last updated: 2017-04-04Bibliographically approved
6. The Söderfors Project: Experimental Hydrokinetic Power Station Deployment and First Results
Open this publication in new window or tab >>The Söderfors Project: Experimental Hydrokinetic Power Station Deployment and First Results
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2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The Division of Electricity at Uppsala University recently deployed an experimental hydrokinetic power station for in-stream experiments at a site in a river. This paper briefly describes the deployment process and reports some initial results from measurements made at the test site.

Keyword
Marine Current Power, Renewable energy, Söderfors, Strömkraft, Förnybar energi, Söderfors
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-209220 (URN)
Conference
10th European Wave and Tidal Energy Conference (EWTEC), 2-5 september, 2013, Aalborg, Denmark
Projects
Marine Current Power
Funder
StandUpSwedish Research Council, 621-2009-4946
Available from: 2013-10-15 Created: 2013-10-15 Last updated: 2017-04-04Bibliographically approved
7. Experimental demonstration of performance of a vertical axis marine current turbine in a river
Open this publication in new window or tab >>Experimental demonstration of performance of a vertical axis marine current turbine in a river
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2016 (English)In: Journal of Renewable and Sustainable Energy, ISSN 1941-7012, E-ISSN 1941-7012, Vol. 8, no 6, 064501Article in journal (Refereed) Published
Abstract [en]

An experimental station for marine current power has been installed in a river. The station comprises a vertical axis turbine with a direct-driven permanent magnet synchronous generator. In measurements of steady-state operation in varying flow conditions, performance comparable to that of turbines designed for significantly higher flow speeds is achieved, demonstrating the viability of electricity generation in low speed (below 1.5 m/s) marine currents.

Keyword
Ocean currents, electric currents, rivers, hydrodynamics, torque
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Ocean and River Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-280762 (URN)10.1063/1.4971817 (DOI)000390115300019 ()
Projects
Marin strömkraft
Funder
Vattenfall ABÅForsk (Ångpanneföreningen's Foundation for Research and Development)StandUp
Note

Övriga finansiärer: J. Gust. Richert Memorial Fund och Bixia Environmental Fund.

Available from: 2016-03-15 Created: 2016-03-15 Last updated: 2017-11-30Bibliographically approved
8. One-Dimensional Modelling of Marine Current Turbine Runaway Behaviour
Open this publication in new window or tab >>One-Dimensional Modelling of Marine Current Turbine Runaway Behaviour
2016 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, no 5, 309Article in journal (Refereed) Published
Abstract [en]

If a turbine loses its electrical load, it will rotate freely and increase speed, eventually achieving that rotational speed which produces zero net torque. This is known as a runaway situation. Unlike many other types of turbine, a marine current turbine will typically overshoot the final runaway speed before slowing down and settling at the runaway speed. Since the hydrodynamic forces acting on the turbine are dependent on rotational speed and acceleration, turbine behaviour during runaway becomes important for load analyses during turbine design. In this article, we consider analytical and numerical models of marine current turbine runaway behaviour in one dimension. The analytical model is found not to capture the overshoot phenomenon, while still providing useful estimates of acceleration at the onset of runaway. The numerical model incorporates turbine wake build-up and predicts a rotational speed overshoot. The predictions of the models are compared against measurements of runaway of a marine current turbine. The models are also used to recreate previously-published results for a tidal turbine and applied to a wind turbine. It is found that both models provide reasonable estimates of maximum accelerations. The numerical model is found to capture the speed overshoot well.

Keyword
marine current turbines; tidal turbines; runaway speed
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-280761 (URN)10.3390/en9050309 (DOI)000377263400001 ()
Funder
Vattenfall ABSwedish Research CouncilÅForsk (Ångpanneföreningen's Foundation for Research and Development)StandUpSwedish Energy Agency
Available from: 2016-03-15 Created: 2016-03-15 Last updated: 2017-11-30Bibliographically approved
9. 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
10. The Söderfors Project: Construction of an Experimental Hydrokinetic Power Station
Open this publication in new window or tab >>The Söderfors Project: Construction of an Experimental Hydrokinetic Power Station
Show others...
2011 (English)In: Proceedings of the 9th European Wave and Tidal Energy Conference, Southampton, UK, 5-9 September 2011, 2011Conference paper, Published paper (Refereed)
Abstract [en]

The Division of Electricity at Uppsala Universityis developing an experimental hydrokinetic power station for instreamexperiments at a site in a river. The purpose of this paperis to present some of the design choices made in the constructionof the experimental station. For background purposes, an outlineof the research project as a whole is also given.

The experimental station will be deployed in the Dal¨alvenRiver at S¨oderfors, whence the project derives its name. Thesite was selected based on several technical and non-technicalreasons. The system comprises a vertically oriented cross-streamaxis turbine and a directly driven permanent magnet generator tobe situated on the riverbed. The necessary power electronics forcontrol and power conversion will be housed in a small measuringstation on shore.

The paper discusses several aspects of the project, thatmight be of interest to other researchers in the field. Variousdesign choices, where different properties become the limiting ordeciding factor in different cases, are discussed along with theirrespective advantages and disadvantages. A brief outlook as tothe future of the project is also given.

Keyword
hydrokinetic energy, vertical axis turbine, lowspeed generator, experimental facility
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-164282 (URN)
Conference
9th European Wave and Tidal Energy Conference, Southampton, UK, 5-9 September 2011
Available from: 2011-12-19 Created: 2011-12-19 Last updated: 2016-04-12

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