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University of California – Berkeley

1. Son, Daewoong. Performance Evaluation and Optimization of a Dual Coaxial-Cylinder System as an Ocean-Wave Energy Converter.

Degree: Mechanical Engineering, 2016, University of California – Berkeley

This research demonstrates the design, optimization, and control of a dual coaxial-cylinder system as an ocean-wave energy converter (WEC). The coaxial-cylinder system consists of a tension-tethered vertical inner cylinder and an annular outer cylinder heaving along the outer surface of the inner cylinder. The relative heave motion between the two cylinders is used to extract energy from incoming waves. An "in-house developed" permanent-magnet linear generator (PMLG), consisting of an array of magnets mounted on the outer cylinder but moving relative to a set of coils installed inside the inner cylinder, is used to convert the mechanical movement into electrical current, thus functioning as a power take-off (PTO) unit. This research consists of the following phases.First, the mathematical modeling, component design and fabrication of the WEC hardware, coupled with the PMLG, were developed. Verification of the predictability and viability of this coupling concept was conducted by comparing predictions with physical-model experiments of about 1:24 scale. The modeling is supplemented by relatively simple, experimentally determined, viscosity-related correction factors on theoretical hydrodynamic coefficients of damping and added mass. The wave-exciting force was well predicted. The modeling is successful for free motion of the cylinder in waves. Second, a series of dry-bench tests on the PMLG unit was used to determine its electro-mechanical properties. The operating condition that enabled maximum useful power output at heave-motion resonance was investigated as a function of magnet-coil gap width and the output payload in the form of electrical resistance. Moreover, the bottom profile of the annular outer cylinder was modified into a curved shape similar to "The Berkeley Wedge" so as to reduce viscous losses and enhance the WEC performance. Viscous damping losses were reduced by as much as 70%, when compared to a flat-bottom shape. This simple change led to a three-fold increase in the heave amplitude of the outer cylinder and a two-fold increase in power output at resonance, when the WEC system was set at the optimal operating conditions. Thirdly, to further maximize the energy-extraction capability for a wide operating range of sea-states, a nonlinear model predictive control (NMPC) methodology was developed for the coupled system. The mechanical to electrical power conversion efficiency of the PMLG, determined in Phase 2, was incorporated in this new control scheme. This NMPC process provided a strongly time-dependent PMLG damping profile in time as the control parameter. The typical optimal time-profile of this damping was found to consist of some intermediate value constrained within the specified damping capacity. To confirm the success of this NMPC strategy, this PMLG damping behavior was implemented electronically into the complete WEC system of Phase 1 and 2. The controller employs a solid-state relay based on a pulse-width modulation technique to mimic analog current flow. Experimental verification in…

Subjects/Keywords: Mechanical engineering; Ocean engineering; Dual Coaxial-Cylinder; Energy Extraction Maximization; Nonlinear Model Predictive Control; Performance Optimization; Permanent-Magnet Linear Generator; Wave Energy Converter

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Son, D. (2016). Performance Evaluation and Optimization of a Dual Coaxial-Cylinder System as an Ocean-Wave Energy Converter. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/5dh8w6rc

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Son, Daewoong. “Performance Evaluation and Optimization of a Dual Coaxial-Cylinder System as an Ocean-Wave Energy Converter.” 2016. Thesis, University of California – Berkeley. Accessed March 05, 2021. http://www.escholarship.org/uc/item/5dh8w6rc.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Son, Daewoong. “Performance Evaluation and Optimization of a Dual Coaxial-Cylinder System as an Ocean-Wave Energy Converter.” 2016. Web. 05 Mar 2021.

Vancouver:

Son D. Performance Evaluation and Optimization of a Dual Coaxial-Cylinder System as an Ocean-Wave Energy Converter. [Internet] [Thesis]. University of California – Berkeley; 2016. [cited 2021 Mar 05]. Available from: http://www.escholarship.org/uc/item/5dh8w6rc.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Son D. Performance Evaluation and Optimization of a Dual Coaxial-Cylinder System as an Ocean-Wave Energy Converter. [Thesis]. University of California – Berkeley; 2016. Available from: http://www.escholarship.org/uc/item/5dh8w6rc

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Κιμουλάκης, Νικόλαος. Ανάπτυξη και σύγκριση εναλλακτικών συζευγμένων ηλεκτρομηχανικών συστημάτων για ηλεκτροπαραγωγή από θαλάσσιο κυματισμό.

Degree: 2010, National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)

The present thesis, concerns the design procedure, modeling and implementation of the optimal configuration of the electric part of an experimental power plant, as well as the study of alternative generating unit configurations in the case of power generation from sea waves. An experimental power plant for power generation from sea waves was constructed on Psitalia in the frame of the research project PAVET 00BE142 entitled “Experimental Plant for Power Generation from Sea Waves”. The entire plant consisted of three similar units, each one involving a coupled hydraulic - mechanical - electrical system for wave energy extraction. Moreover, the case of linear synchronous generator with permanent magnets (LPMSG), as alternative unit for electric power generation from sea waves, has been studied. A particular, linear generator with permanent magnets was designed, accounting the features of the sea wave and the behaviour of the floating buoy. Appropriate coupled electromagnetic-mechanical-hydraulic models incorporating Finite Element Analysis (FEA) have been developed, enabling a dynamic simulation of the whole system performance involving a detailed field analysis of the permanent magnet linear generator. Also, a new hybrid simulation model, incorporating finite elements (FE) combined with analytical solution (macroelement) in the air gap area accounting for skewed magnets in linear generators (LPMSG) have been developed. The results of simulation of performance combined with the experimental measurements, illustrate the suitability of the developed models in applications for power generation from sea waves.

Στα πλαίσια της παρούσας εργασίας διερευνήθηκαν οι πιθανές εναλλακτικές διαμορφώσεις συζευγμένων ηλεκτρομηχανικών συστημάτων, κατάλληλων για την παραγωγή ηλεκτρικής ενέργειας από τον θαλάσσιο κυμάτισμά. Επίσης αναπτύχθηκαν κατάλληλα αριθμητικά μοντέλα για την προσομοίωση της λειτουργίας των απαιτούμενων συζευγμένων υποσυστημάτων (υδραυλικού - μηχανικού - ηλεκτρικού), για την σύνθεση μιας μονάδας ηλεκτροπαραγωγής με εκμετάλλευση την ενέργειας του θαλάσσιου κυματισμού. Τα μοντέλα εφαρμόστηκαν σε επιδεικτικό πειραματικό σταθμό μετατροπής της ενέργειας των θαλάσσιών κυμάτων σε ηλεκτρική, που κατασκευάστηκε στην Ψυτάλλεια στα πλαίσια του ερευνητικού έργου ΠΑΒΕΤ 00ΒΕ142, με τίτλο «Πειραματικός σταθμός παραγωγής ηλεκτρικής ενέργειας από θαλάσσιο κυμάτισμά». Ως εναλλακτικοί τύποι γεννητριών που μπορούν να χρησιμοποιηθούν για την ηλεκτροπαραγωγή από θαλάσσιο κυμάτισμά, εξετάστηκαν η γεννήτρια συνεχούς ρεύματος ξένης διέγερσης και η γραμμική γεννήτρια μονίμων μαγνητών. Τα δύο είδη γεννητριών, απαιτούν πλήρη ανάλυση της κατανομής του μαγνητικού τους πεδίου, καθώς ο εφαρμοζόμενος έλεγχος με στόχο την βελτιστοποίηση της παραγόμενης ενέργειας ακόμη και από κυμάτισμά χαμηλού ενεργειακού περιεχομένου, μπορεί να οδηγήσει σε βραχυχρόνια εμφάνιση φαινομένων τοπικού κορεσμού στο μαγνητικό υλικό των γεννητριών. Για την ανάλυση της κατανομής του μαγνητικού πεδίου γραμμικών γεννητριών μονίμων μαγνητών, αναπτύχθηκε μια νέα μεικτή τεχνική…

Subjects/Keywords: Ηλεκτροπαραγωγή από θαλάσσιο κυματισμό; Συζευγμένα μοντέλα προσομοίωσης; Μέθοδος πεπερασμένων στοιχείων; Μεικτή τεχνική πεπερασμένων στοιχείων - αναλυτικών λύσεων; Γραμμική γεννήτρια μονίμων μαγνητών; Κλίση μαγνητών; Power generation from sea waves; Wave energy extraction; Coupled simulation models; Finite elements method; Special air gap macroelement; Linear permanent magnet generator; Magnet skew

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Κιμουλάκης, . . (2010). Ανάπτυξη και σύγκριση εναλλακτικών συζευγμένων ηλεκτρομηχανικών συστημάτων για ηλεκτροπαραγωγή από θαλάσσιο κυματισμό. (Thesis). National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ). Retrieved from http://hdl.handle.net/10442/hedi/18842

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Κιμουλάκης, Νικόλαος. “Ανάπτυξη και σύγκριση εναλλακτικών συζευγμένων ηλεκτρομηχανικών συστημάτων για ηλεκτροπαραγωγή από θαλάσσιο κυματισμό.” 2010. Thesis, National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ). Accessed March 05, 2021. http://hdl.handle.net/10442/hedi/18842.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Κιμουλάκης, Νικόλαος. “Ανάπτυξη και σύγκριση εναλλακτικών συζευγμένων ηλεκτρομηχανικών συστημάτων για ηλεκτροπαραγωγή από θαλάσσιο κυματισμό.” 2010. Web. 05 Mar 2021.

Vancouver:

Κιμουλάκης . Ανάπτυξη και σύγκριση εναλλακτικών συζευγμένων ηλεκτρομηχανικών συστημάτων για ηλεκτροπαραγωγή από θαλάσσιο κυματισμό. [Internet] [Thesis]. National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ); 2010. [cited 2021 Mar 05]. Available from: http://hdl.handle.net/10442/hedi/18842.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Κιμουλάκης . Ανάπτυξη και σύγκριση εναλλακτικών συζευγμένων ηλεκτρομηχανικών συστημάτων για ηλεκτροπαραγωγή από θαλάσσιο κυματισμό. [Thesis]. National Technical University of Athens (NTUA); Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ); 2010. Available from: http://hdl.handle.net/10442/hedi/18842

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.