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Optimization of Point Absorber Wave Energy Parks
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Renewable energies are believed to play the key role in assuring a future of sustainable energy supply and low carbon emissions. Particularly, this thesis focus on wave energy, which is created by extracting the power stored in the waves of the oceans. In order for wave energy to become a commercialized form of energy, modular deployment of many wave energy converters (WECs) together will be required in the upcoming future. This design will thus allow to benefit, among others, from the modular construction, the shared electrical cables connections and moorings, the reduction in the power fluctuations and reduction of deployment and maintenance costs. When it comes to arrays, the complexity of the design process increase enormously compared with the single WEC, given the mutual influence of most of the design parameters (i.e. hydrodynamic and electrical interactions, dimensions, geometrical layout, wave climate etc.). Uppsala University has developed and tested WECs since 2001, with the first offshore deployment held in 2006. The device is classified as a point absorber and consists in a linear electric generator located on the seabed, driven in the vertical direction by the motion of a floating buoy at the surface. Nowadays, one of the difficulties of the sector is that the cost of electricity is still too high and not competitive, due to high capital and operational costs and low survivability. Therefore, one step to try to reduce these costs is the development of reliable and fast optimization tools for parks of many units. In this thesis, a first attempt of systematic optimization for arrays of the Uppsala University WEC has been proposed. A genetic algorithm (GA) has been used to optimize the geometry of the floater and the damping coefficient of the generator of a single device. Afterwards, the optimal layout of parks up to 14 devices has been studied using two different codes, a continuous and a discrete variables real coded GA. Moreover, the method has been extended to study arrays with devices of different dimensions. A deterministic evaluation of small array layouts in real wave climate has also been carried out. Finally, a physical scale test has been initiated which will allow the validation of the results. A multi--parameter optimization of wave power arrays of the Uppsala University WEC has been shown to be possible and represents a tool that could help to reduce the total cost of electricity, enhance the performance of wave power plants and improve the reliability.

Place, publisher, year, edition, pages
Uppsala: Uppsala University, Department of Engineering Sciences , 2018. , p. 59
Series
UURIE / Uppsala University, Department of Engineering Sciences, ISSN 0349-8352 ; 353-18L
Keyword [en]
Wave energy arrays, genetic algorithm, optimization, WEC, hydrodynamic interaction
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science
Identifiers
URN: urn:nbn:se:uu:diva-337772OAI: oai:DiVA.org:uu-337772DiVA: diva2:1171500
Presentation
2018-02-27, 2005 Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 14:00 (English)
Opponent
Supervisors
Available from: 2018-01-31 Created: 2018-01-08 Last updated: 2018-02-05Bibliographically approved
List of papers
1. Parameter optimization in wave energy design by a genetic algorithm
Open this publication in new window or tab >>Parameter optimization in wave energy design by a genetic algorithm
2017 (English)In: Proceeings 32nd International Workshop on Water Waves and Floating Bodies, 2017Conference paper, Published paper (Refereed)
National Category
Energy Engineering
Identifiers
urn:nbn:se:uu:diva-329391 (URN)
Conference
32nd International Workshop on Water Waves and Floating Bodies (IWWWFB), 23-26th April, 2017, Dalian, China.
Available from: 2017-09-14 Created: 2017-09-14 Last updated: 2018-01-08Bibliographically approved
2. Layout design of wave energy parks by a genetic algorithm
Open this publication in new window or tab >>Layout design of wave energy parks by a genetic algorithm
(English)In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258Article in journal (Refereed) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-337711 (URN)
Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-01-08
3. Multi-parameter optimization of hybrid arrays of point absorber Wave Energy Converters
Open this publication in new window or tab >>Multi-parameter optimization of hybrid arrays of point absorber Wave Energy Converters
Show others...
2017 (English)In: Proceedings of the 12th European Wave and Tidal Energy Conference, 2017Conference paper, Published paper (Refereed)
Series
European Wave and Tidal Energy Conference Series, ISSN 2309-1983
National Category
Marine Engineering Energy Engineering
Identifiers
urn:nbn:se:uu:diva-329393 (URN)
Conference
12th European Wave and Tidal Energy Conference (EWTEC), Cork, Ireland, August 27-31, 2017.
Available from: 2017-09-14 Created: 2017-09-14 Last updated: 2018-01-08Bibliographically approved
4. Optimal Constant Damping Control of a Point Absorber with Linear Generator in Different Sea States: Comparision of Simulation and Scale Test
Open this publication in new window or tab >>Optimal Constant Damping Control of a Point Absorber with Linear Generator in Different Sea States: Comparision of Simulation and Scale Test
Show others...
2017 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-336686 (URN)
Conference
12th European Wave and Tidal Energy Conference
Available from: 2017-12-15 Created: 2017-12-15 Last updated: 2018-01-08
5. Wave energy farm design in real wave climates: the Italian offshore
Open this publication in new window or tab >>Wave energy farm design in real wave climates: the Italian offshore
Show others...
2017 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 122, p. 378-389Article in journal (Refereed) Published
Abstract [en]

The work focuses on hydrodynamic interactions between heaving wave energy converters (WEC). Wave parks of four devices are simulated in the time domain by a hydrodynamic-electromagnetic model, coupled with a boundary element code for the estimation of hydrodynamic parameters. Different layouts (linear, square and rhombus), WEC separation distances (5, 10, 20 and 30 buoy diameters) and incident wave directions (30 degrees apart) are considered to assess the effect of design parameters on array power production. Then, a site-specific design optimization is carried out for different Italian locations and some key insights on wave farm design in real wave climates are provided. The results show that the effect of wave interactions on energy absorption is not expected to be a main issue, as long as the devices are separated by at least 10 buoy diameters and that the layouts are oriented to achieve the maximum energy absorption for the prevailing wave direction.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2017
Keyword
Renewable energy, Wave energy, Arrays, Hydrodynamic interactions, Numerical modelling, Italy
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-321986 (URN)10.1016/j.energy.2017.01.094 (DOI)000399267100033 ()
Available from: 2017-05-15 Created: 2017-05-15 Last updated: 2018-01-08

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