| 11. |
- Carpman, Nicole, et al.
(författare)
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Measurements of tidal current velocities in the Folda fjord, Norway, with the use of a vessel mounted ADCP
- 2014
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Ingår i: 33Rd International Conference On Ocean, Offshore And Arctic Engineering, 2014, Vol 8A. - 9780791845509
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Konferensbidrag (refereegranskat)abstract
- Measurements of tidal current water velocities is an important first step in evaluating the potential for a tidal site to be used as a renewable energy resource. For this reason, on site measurements are performed at the inlet of a fjord situated at the coast of Norway. The site has an average width of 580 m and adepth of 10-15 m which is narrow and shallow enough to give rise to water velocities that can be of use for energy conversion. With the use of an Acoustic Doppler Current Profiler (ADCP) cross-section measurements are conducted along four transects. The measurements covered flood and ebb currents around one tide and the data give a first approximation of the magnitude and distribution of the flow field. Depth averaged mean current velocities are calculated along the transects for horizontal bins with sizes in the order of 50 x 50 m. Maximum mean velocity for the flood currents were 1.31 m/s and 1.46 m/s for the ebb currents. The measurements show that even a small amount of data can give an indication of the potential and characteristics ofthe site.
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| 12. |
- Castellucci, Valeria, et al.
(författare)
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Tidal effect compensation system for point absorbing wave energy converters
- 2013
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Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 51, s. 247-254
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies show that there is a correlation between water level and energy absorption values for the studied wave energy converters: the absorption decreases when the water levels deviate from average. The situation appears during tides when the water level changes significantly. The main objective of the paper is to present a first attempt to increase the energy absorption during tides by designing and realizing a small-scale model of a point absorber equipped with a device that is able to adjust the length of the rope connected to the generator. The adjustment is achieved by a screw that moves upwards in the presence of low tides and downwards in the presence of high tides. Numerical results as well as experimental tests suggest that the solution adopted to minimize the tidal effect on the power generation shows potential for further development.
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| 13. |
- Castellucci, Valeria, et al.
(författare)
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Wireless System for Tidal Effect Compensation in the Lysekil Research Site
- 2012
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Ingår i: Proceedings of the ASME 31st International Conference on Ocean, Offshore and Arctic Engineering, vol. 7. - 9780791844946 ; , s. 293-298
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Konferensbidrag (refereegranskat)abstract
- This paper describes, firstly, the rope adjustment device for wave energy converters (WECs) to minimize the tidal effect on the electricity production and, secondly, a wireless communication network between point absorbing WECs in the Lysekil Research Site and a computer station at the Department of Engineering Sciences at Uppsala University. The device is driven by a motor that activates when the main water level deviates from the average. The adjustment is achieved through a screw that moves upwards during low tides and downwards during high tides. For the purpose of testing the device in the research site, a wireless connection between the buoy in the sea and a computer on land will be designed. A sensor located close to the research site monitors the sea water level and, every time a significant variation is registered, it sends wirelessly a signal to the data logger that controls the power to the motor The position of the screw is observed by a second sensor and the measurements are retrieved back to Uppsala via GSM connection. The full scale device is tested in the lab and it is demonstrated to work properly, requiring less than 750 W to lift and lower different loads. Moreover, the wireless communication network is designed and once it will be built, it will allow to recall and store data, send information from one node of the system to another, monitor the proper functioning of the device and modify the control as desired.
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| 14. |
- Chatzigiannakou, Maria A., et al.
(författare)
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Offshore Deployment of Point Absorbing Wave Energy Converters with a Direct Driven Linear Generator Power Take-Off at the Lysekil Test Site
- 2014
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Ingår i: 33Rd International Conference On Ocean, Offshore And Arctic Engineering, 2014, Vol 9A. - 9780791845530
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Konferensbidrag (refereegranskat)abstract
- Within the year 2013, four linear generators with point absorber buoy systems were deployed in the Lysekil test site. Until now, deployments of these point absorbing wave energy converters have been expensive, time consuming, complicated and raised safety issues. In the present paper, we focus on the analysis and optimization of the offshore deployment process of wave energy converters with a linear generator power take-off which has been constructed by Uppsala University. To address the crucial issues regarding the deployment difficulties, case study of previous offshore deployments at the Lysekil test site are presented regarding such parameters as safety, cost and time efficiency. It was discovered that the deployment process can be improved significantly, mainly by using new technologies, e.g., new specialized deployment vessels, underwater robots for inspections and for connecting cables and an automatized pressurizing process. Addressing the main deployment difficulties and constrains leads us to discovery of methods that makes offshore deployments more cost-efficient and faster, in a safety context.
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| 15. |
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| 16. |
- de Santiago, Juan, et al.
(författare)
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Electrical Motor Drivelines in Commercial All Electric Vehicles : a Review
- 2012
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 61:2, s. 475-484
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a critical review of the drivelines in all Electric Vehicles (EVs). The motor topologies that are the best candidates to be used in EVs are presented. The advantages and disadvantages of each electric motor type are discussed from a system perspective. A survey of the electric motors used in commercial EVs is presented. The survey shows that car manufacturers are very conservative when it comes to introducing new technologies. Most of the EV’s in the market mount a single induction or permanent magnet motor with a traditional mechanic driveline with a differential. The study illustrates that comparisons between the different motors are made difficult by the large number of parameters and the lack of a recommended test scheme. The authors propose that a standardized drive cycle is used to test and compare motors.
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| 17. |
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| 18. |
- Dolguntseva, Irina, 1981-, et al.
(författare)
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Risk based estimation of failure in a steel wire used for the wave energy converter connection line
- 2014
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Konferensbidrag (refereegranskat)abstract
- The wave energy converter being developed at Uppsala University is of a point absorber type utilizing heaving motion of waves with a direct driven linear generator power take off. The point absorber, a buoy, is placed on the sea surface and is connected to the translator by a connection line. The connection line service life is of large importance for the lifetime of the entire device. Steel wire used as the connection line should be chosen to withstand loadings with different amplitude and frequency. In the present study, the risk of failure in the connection line is estimated.
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| 19. |
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| 20. |
- Ekergård, Boel, et al.
(författare)
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Axial Force Damper in a Linear Wave Energy Converter
- 2013
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Ingår i: Development and Applications of Oceanic Engineering (DAOE). - 2325-3762. ; 2:2, s. 33-38
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study on the axial force damper in a wave energy converter. The converter itself consists of a linear generator placed on the ocean floor connected to a buoy at the ocean surface. As the development of the complete system goes forward, the economical perspective becomes more and more important. In order to ensure an economically viable alternative to the electric energy conversion, the costs associated with the use of materials have to be reduced while the survivability of the wave power unit has to be prolonged. The study presented in this paper increases the knowledge on axial forces and illustrates the damping system required to prevent the failure of the hull which houses the generator. The results are aimed to be utilized in the future design of wave energy converters and influence the choice of materials, the total costs and prolong the survivability of the wave energy converters in harsh wave climates.
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