"Submitted in partial fulfillment of the requirements for the degree of Master of Business Administration from the Naval Postgraduate School, June 2008." / Advisor(s): Dew, Nicholas ; Ventresca, Marc. "June 2008." "MBA professional report"--Cover. Description based on title screen as viewed on August 7, 2008. Includes bibliographical references (p. 91-97). Also available in print.

Thesis (M.E. (Res.))--University of Sydney, 1996. / Bibliography: leaves 141-142. Also available in print form.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "May, 2008." Includes bibliographical references (leaves 144-147). Online version available on the World Wide Web.

Thesis (doctoral)--Tallinn University of Technology, 2009. / Includes bibliographical references.

No description available.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on November 13, 2009). Thesis advisor: Dr. Patrick S. Market Includes bibliographical references.

Η παρούσα διπλωματική εργασία πραγματεύεται αφ’ενός μεν την ανάλυση, μέσω προσομοίωσης, ενός αιολικού συστήματος παραγωγής ηλεκτρικής ενέργειας, συνδεδεμένο στο δίκτυο χαμηλής τάσης αφ’ετέρου δε την κατασκευή ενός τμήματος του συστήματος αυτού και ειδικότερα του μετατροπέα ανύψωσης τάσης. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών του Πανεπιστημίου Πατρών. Το αιολικό σύστημα αποτελείται από μία ανεμογεννήτρια με σύγχρονη γεννήτρια μόνιμων μαγνητών και διατάξεις ηλεκτρονικών ισχύος που μετατρέπουν αρχικά την εναλλασσόμενη τάση σε συνεχή και στη συνέχεια τη συνεχή τάση σε εναλλασσόμενη, συχνότητας 50Hz, ώστε να επιτευχθεί σύνδεση με το δίκτυο χαμηλής τάσης. Πιο συγκεκριμένα, χρησιμοποιούνται κατά σειρά μία μη ελεγχόμενη ανορθωτική γέφυρα με διόδους για την ανόρθωση της τάσης που παράγεται από τη γεννήτρια, ένας μετατροπέας τύπου Flyback για την ανύψωση και σταθεροποίηση της τάσης και τέλος, ένας μονοφασικός αντιστροφέας τάσης αποτελούμενος από ημιαγωγικούς διακόπτες τύπου MOSFET ελεγχόμενος με τη μέθοδο SPWM. Τέλος, η έξοδος του αντιστροφέα, μέσω κατάλληλου φίλτρου LC, συνδέεται στο δίκτυο. Πρώτος στόχος της εργασίας είναι αρχικά η ανάλυση του κάθε υποσυστήματος και συνέχεια του συνολικού συστήματος της ανεμογεννήτριας. Επίσης, σκοπός της εργασίας αυτής είναι η κατασκευή διάταξης ανύψωσης και σταθεροποίησης της τάσης για τη σύνδεση της ανεμογεννήτριας του εργαστηρίου, ισχύος 1kW, με το δίκτυο χαμηλής τάσης, ώστε να χρησιμοποιηθεί για εργαστηριακούς και ερευνητικούς σκοπούς. Αρχικά, μετά από μια σύντομη αναφορά στα συστήματα μετατροπής αιολικής ενέργειας σε ηλεκτρική, γίνεται μια λεπτομερής ανάλυση των προδιαγραφών του υπό μελέτη αιολικού συστήματος. Στη συνέχεια γίνεται αναλυτική περιγραφή της τοπολογίας ανύψωσης και σταθεροποίησης τάσης, τύπου Flyback. Κατόπιν, μοντελοποιούνται τα επιμέρους μέρη του αιολικού συστήματος, δίνοντας ιδιαίτερη έμφαση στον μετατροπέα ανύψωσης και σταθεροποίησης της τάσης. Ακολούθως τα επιμέρους υποσυστήματα προσομοιώνονται ώστε να μελετηθεί λεπτομερώς η λειτουργία του καθενός στο σύστημά μας, ενώ τέλος, γίνεται προσομοίωση ολόκληρου του συστήματος ώστε να περιγραφεί η συμβολή της ανεμογεννήτριας στο δίκτυο χαμηλής τάσης. Εν τέλει, αναλύονται όλα τα τεχνικά και κατασκευαστικά χαρακτηριστικά του μετατροπέα Flyback και των κυκλωμάτων από τα οποία συγκροτείται και παρατίθενται παλμογραφήματα και μετρήσεις από την διενέργεια πειραματικών μετρήσεων. / --

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Please refer to full text for abstract.

A forte expansão da geração eólica é uma tendência mundial que altera a estrutura, o planejamento, a operação e a dinâmica dos sistemas de potência. Dessa forma, é importante que as unidades de geração eólica assumam responsabilidade pela confiabilidade e estabilidade do sistema de potência. Um bom desempenho transitório e uma boa margem de estabilidade para o sistema de potência dependem de estudos técnicos e da utilização de estratégias adequadas de controle. Nesse contexto, o presente trabalho propõe a inclusão de uma malha de controle suplementar em unidades eólicas de geração baseadas em gerador de indução duplamente alimentado. O objetivo da malha de controle suplementar proposta é melhorar a margem de estabilidade a pequenas perturbações de unidades eólicas e do sistema de potência. Controladores de amortecimento para a malha de controle suplementar proposta são projetados para amortecer as oscilações eletromecânicas causadas por unidades eólicas e por unidades de geração convencionais baseadas em gerador síncrono. Uma análise para definir a melhor entrada de controle para a inclusão da malha de controle suplementar da unidade de geração eólica é feita usando resíduos da função de transferência. As análises e testes são realizados usando dois sistemas diferentes: sistema composto por uma única unidade eólica conectada a um barramento infinito e sistema constituído por uma unidade eólica e uma unidade de geração convencional baseada em gerador síncrono conectadas a um barramento infinito. Duas diferentes metodologias são adotadas para o projeto/síntese do controlador da malha de controle suplementar. Uma metodologia de projeto é baseada na teoria de controle clássico e a outra metodologia baseia-se na teoria de controle modernorobusto. Os resultados obtidos mostram que a inclusão da malha de controle suplementar proposta foi eficaz na melhoria da margem de estabilidade a pequenas perturbações do sistema de potência. Esses resultados demonstram também que unidades eólicas baseadas em gerador de indução duplamente alimentado podem contribuir com a melhoria da margem de estabilidade do sistema de potência. / The strong expansion of wind generation is a global trend that changes the structure, planning operation and dynamics of power systems. Thus, it’s important that the units of wind generation take responsibility for the reliability and stability of power system. A good transient performance and good degree of stability for the power system depend of technical studies and of the use of appropriate strategy controls. In this context, this study proposes the inclusion of a additional control loop on generating wind turbines based on doubly fed induction generator. The purpose of the proposed additional control loop is to improve the stability margin to small perturbations of wind turbines and power system. Damping controllers for the proposes additional control loop are designed to damp the oscillations caused by the wind turbines and conventional generating units based on synchronous generator. An analysis to determinate the best control input for the inclusion of the control loop further wind power generation unit is performed using waste transfer function. The analyses and tests are performed using two different test systems: system comprising a single wind unit connected to a infinite bus and a system comprising a wind unit and a wind power generation based on the conventional synchronous generator connected to an infinite bus. Two different methods are adopted for the project / synthesis of the controller of the additional control loop. A project methodology is based on classical control theory and the other is based on modern-robust control theory. The obtained results show that the inclusion of additional control loop was efficient in improving the stability margin of small perturbations of the power system. These results also demonstrate that wind turbines based in doubly fed induction generator can contribute to improving the stability margin of the power system.

When using an intermittent source of energy such as wind power together with a synchronous machine a frequency converter system is needed to decouple the generator from the grid, due to the fluctuations in wind speed resulting in fluctuating electrical frequency. The aim of this master's thesis is to investigate how different types of rectification methods affect permanent magnet synchronous machines of different saliency ratios. A literature study was carried out to review the research within the area and to acquire the necessary knowledge to carry out the work. Two simulation models were created that include a permanent magnet synchronous generator driven by a wind turbine and connected to the grid via a frequency converter, where one model utilizes active rectification and one utilizes passive rectification. The simulation models were verified by carrying out an experiment on a similar setup, which showed that the simulation results coincide well with the results of the experiment. The results of the simulation study were then used to compare the rectification systems as well as investigate the affect that rotor saliency has on the system. It was shown that the active rectification provided a higher efficiency than the passive rectification system, however the saliency of the rotor had little effect on the system