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Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Marine Current Power)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. (Marine Current Power)
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.
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.

Place, publisher, year, edition, pages
2015. Vol. 8, no 5, 4572-4586 p.
Keyword [en]
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: urn:nbn:se:uu:diva-244939DOI: 10.3390/en8054572ISI: 000356879600064OAI: oai:DiVA.org:uu-244939DiVA: diva2:790086
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
In thesis
1. Experimental Results of a Load-Controlled Vertical Axis Marine Current Energy Converter
Open this publication in new window or tab >>Experimental Results of a Load-Controlled Vertical Axis Marine Current Energy Converter
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis investigates the load control of a marine current energy converter using a vertical axis turbine mounted on a permanent magnet synchronous generator. The purpose of this thesis is to show the work done in the so far relatively uncharted territory of control systems for hydro kinetic energy conversion. The work is in its early stage and is meant to serve as a guide forfuture development of the control system.

An experimental power station has been deployed and the first results are presented.

A comparison between three load control methods has been made; a fixedAC load, a fixed pulse width modulated DC load and a DC bus voltage control of a DC load. Experimental results show that the DC bus voltage control reduces the variation of rotational speed with a factor of 3.5. For all three cases, the tip speed ratio of the turbine can be kept close to the expected optimal tip speed ratio. However, for all three cases the average extracted power was significantly lower than the average power available in the turbine times the estimated maximum power coefficient. A maximum power point tracking system, with or without water velocity measurement, should increase the average extracted power.

A simulation model has been validated using experimental data. The simulated system consists of the electrical system and a hydrodynamic vortex model for the turbine. Experiments of no load operation were conducted to calibrate the drag losses of the turbine. Simulations were able to predict the behaviour in a step response for a change in tip speed ratio when the turbine was operated close to optimal tip speed ratio. The start position of the turbine was varied in the simulation to view the influence on the step response from a changed turbine position relative to the direction of the water flow.

Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2015. 53 p.
Series
UURIE / Uppsala University, Department of Engineering Sciences, ISSN 0349-8352 ; 345-15L
Keyword
Marine Current; Vertical Axis; Load Control;
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-268867 (URN)
Presentation
2015-12-16, Å4101, Lägerhyddsvägen 1, Ångströmlaboratoriet, Uppsala, 09:15 (English)
Opponent
Supervisors
Funder
StandUpÅForsk (Ångpanneföreningen's Foundation for Research and Development)Vattenfall ABSwedish Research CouncilSwedish Energy Agency
Note

Funders: J Gust Richert, Bixia Miljöfond

Available from: 2015-12-10 Created: 2015-12-10 Last updated: 2015-12-10Bibliographically approved
2. Marine Current Energy Conversion
Open this publication in new window or tab >>Marine Current Energy Conversion
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
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:nbn:se:uu:diva-280763 (URN)978-91-554-9510-7 (ISBN)
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

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