Στην παρούσα διπλωματική εργασία πραγματοποιείται μελέτη της επίδρασης ενός συστήματος διασύνδεσης ανεμογεννήτριας με το δίκτυο μέσης τάσης, όσον αφορά την έγχυση αρμονικών από την ανεμογεννήτρια προς το δίκτυο. Η μελέτη περιλαμβάνει τη μοντελοποίηση κάθε τμήματος ενός δικτύου μέσης τάσης με πραγματικά στοιχεία που πάρθηκαν από τη ΔΕΗ. Επιπλέον, μοντελοποιείται μια ανεμογεννήτρια τύπου σύγχρονης μόνιμων μαγνητών, καθώς και όλοι οι ηλεκτρονικοί μετατροπείς ισχύος που απαιτούνται για τη διασύνδεση αυτής με το δίκτυο μέσης τάσης. Όλα τα επιμέρους μοντέλα διασυνδέονται μεταξύ τους ώστε να αποτελέσουν το συνολικό μοντέλο που περιλαμβάνει το δίκτυο μέσης τάσης με τις γραμμές μεταφοράς, τους μετασχηματιστές, τα φορτία και τους πυκνωτές αντιστάθμισης που διαθέτει και την ανεμογεννήτρια μαζί με τους μετατροπείς συνδεδεμένη σε ένα ζυγό του δικτύου. Από το μοντέλο αυτό εξάγεται το αρμονικό περιεχόμενο τόσο στο ζυγό της ανεμογεννήτριας όσο και σε διπλανούς ζυγούς και συγκρίνεται κάθε φορά με το πρότυπο IEC 61000-3-6 που θέτει τα όρια για την έγχυση αρμονικών στο δίκτυο μέσης τάσης. Αρχικά, γίνεται μια αναφορά στα πλεονεκτήματα της αιολικής ενέργειας έναντι των άλλων συμβατικών μορφών ενέργειας. Επιπλέον, αναφέρονται τα προβλήματα που δημιουργούνται από την παρουσία ανώτερων αρμονικών στο δίκτυο. Έπειτα, πραγματοποιείται θεωρητική ανάλυση κάθε τμήματος του δικτύου μέσης τάσης. Για κάθε τμήμα δημιουργείται, επίσης, ένα μοντέλο στο Matlab/Simulink που βασίζεται σε στοιχεία από τη ΔΕΗ και εξισώσεις που αφορούν το εκάστοτε τμήμα. Στη συνέχεια, αναλύεται και μοντελοποιείται στο Matlab/Simulink και κάθε τμήμα του συστήματος διασύνδεσης της ανεμογεννήτριας με το δίκτυο μέσης τάσης που περιλαμβάνει την ανεμογεννήτρια τύπου σύγχρονης μόνιμων μαγνητών, ανορθωτική διάταξη, μετατροπέα συνεχούς τάσης σε συνεχή, τριφασικό αντιστροφέα, φίλτρο και μετασχηματιστή. Για κάθε μετατροπέα αναλύεται και μοντελοποιείται και έλεγχος κλειστού βρόχου. Τέλος, τα επιμέρους μοντέλα συγκροτούνται σε ένα συνολικό μοντέλο. Μεταβάλλοντας το συντελεστή φόρτισης των μετασχηματιστών του δικτύου, το συντελεστή ισχύος και το πλήθος των ανεμογεννητριών που συνδέονται στον ίδιο ζυγό, εξάγεται το αρμονικό περιεχόμενο για διάφορους ζυγούς και ελέγχεται αν αυτό συμφωνεί με το πρότυπο IEC 61000-3-6. Επιπλέον, εξετάζεται το αρμονικό περιεχόμενο της τάσης, όταν ο ζυγός διασύνδεσης αλλάζει θέση μέσα στο υπό μελέτη δίκτυο, καθώς και όταν αλλάζει η ταχύτητα του ανέμου. / In the present diploma thesis a study of the effect of a wind turbine system interconnection with medium voltage grid is conducted, in terms of harmonic injection of the turbine to the grid. The study includes the modeling of each part of a medium voltage grid with actual data taken from the Public Power Corporation of Greece. Furthermore, a synchronous wind turbine with permanent magnets is modeled along with all the electronic power converters that are required for the interconnection with the medium voltage grid. All the individual models are connected together to form the overall model, including the medium voltage transmission lines, transformers, loads and their compensation capacitors, along with the wind turbine and the power converters. The wind turbine is connected in a bus of the medium voltage grid. Then, the harmonic content in both the bus of the wind turbine and in other buses of the grid is extracted and compared with the standard IEC 61000-3-6 that sets the limits for harmonic injection in medium voltage grid. Initially, the advantages of use of wind energy are mentioned compared to other conventional forms of energy. Furthermore, the problems caused by the presence of harmonics in the grid are discussed. A theoretical analysis of each section of the medium voltage grid is conducted. For each section, a model in Matlab / Simulink is also created, based on data from the Public Power Corporation of Greece and on equations related to each section. Then, every part of the system connecting the wind turbine to the medium voltage grid is analyzed and modeled in Matlab/Simulink. This system consists of a synchronous wind turbine with permanent magnets, DC-to-DC converter, three-phase inverter, filter and transformer. A closed loop control for each converter is also analyzed and modeled. Finally, the aforementioned models are built up into one single model. By varying the load factor of the grid transformers, the power factor and the number of wind turbines connected to the same bus, the harmonic content of various buses is extracted and checked if it complies with the standard IEC 61000-3-6. Moreover, the harmonic content of the voltage is calculated, when the system of wind turbine changes position in the present medium voltage grid, as well as when the wind speed is changed.

Στις μέρες μας οι συνεχώς αυξανόμενες ενεργειακές ανάγκες, καθώς και η απαίτηση των κοινωνιών για ένα πιο καθαρό περιβάλλον, έχουν κάνει τις ανανεώσιμες πηγές ενέργειας όλο και πιο ελκυστικές ως προς την εκμετάλλευση τους. Η αξιοποίηση της αιολικής ενέργειας στην παραγωγή ηλεκτρικής ενέργειας κερδίζει όλο και περισσότερο έδαφος. Η τεχνολογία των αιολικών συστημάτων αναπτύσσεται συνεχώς ,με αποτέλεσμα να υπάρχουν διάφορες κατηγορίες αυτών, ανάλογα με τη χρήση για την οποία προορίζονται. Στην παρούσα διπλωματική μου εργασία, μελετάται ένα αιολικό σύστημα μεταβλητών στροφών που χρησιμοποιεί μία παραλλαγή της επαγωγικής μηχανής Διπλής Τροφοδοσίας. Η διαφοροποίηση του έγκειται στον επιπλέον dc/ac μετατροπέα που χρησιμοποιείται, προκειμένου να ελέγξουμε την τάση που μπορεί να δει ο στάτης. Μ΄ αυτό τον τρόπο, το αιολικό σύστημα μιας γεννήτριας διπλής τροφοδοσίας γίνεται ακόμα πιο αξιόπιστο, συνεχίζοντας την παραγωγή ισχύος και παραμένοντας συνδεδεμένο με το δίκτυο σε περίπτωση σφάλματος στην πλευρά του δικτύου. Στη μελέτη αυτή, αφού εξαγάγαμε το μαθηματικό μοντέλο του συστήματος και το προσομοιώσαμε σε περιβάλλον Matlab - Simulink, δοκιμάσαμε το σύστημα σε συνθήκες ύπαρξης σφάλματος στο δίκτυο. Στο σύστημα εφαρμόστηκαν κλασικές τεχνικές ελέγχου,με στόχο τη διατήρηση της μέγιστης απομάστευσης ισχύος από το σύστημα, την αύξηση της αντοχής του σε σφάλματα από την πλευρά του δικτύου, καθώς και τη μη αποσύνδεση του συστήματος από το δίκτυο σε μία τέτοια περίπτωση. Τέλος, συγκρίναμε τη συμπεριφορά αυτού του συστήματος με τη συμπεριφορά ενός κλασικού αιολικού συστήματος με επαγωγική γεννήτρια Διπλής Τροφοδοσίας και παραθέσαμε τις διαφορές. / The increasingly energy demands in our days and also the modern societies demand for a greener environment, have made the electrical energy production from renewable energy sources more attractive. The use of wind energy in the electrical energy production is having more and more fervent supporters. The technology and the types of the wind systems varies, depending on the use and the environmental conditions. In my diploma thesis I designed, we will study a variation of a wind system with a variable speed operation with a Doubly Fed Induction Generator. In this system we also use a dc/ac converter in order to control the voltage which the stator can “see”. Using this converter the wind system with a DFIG is more reliable and remains connected to the ac grid, maintaining the maximum power production, in case of a fault on grid side. In this thesis, after we made the mathematical model with a great accuracy and simulated using Matlab - Simulink, we tested it under conditions of different voltage sags from the side of the grid. In order to control the system and maintaining the power production power at the maximum level, we used classic control methods, and as a result, we achieved to keep the maximum level of power production and to keep the wind system connected to the grid in a scenario of a grid side fault. Finally, we compared the behavior of the system we designed with the wind system with the classic DFIG and we presented the differences.

A new concept, the multi level voltage/current reinjection ac/dc conversion, is described in this thesis. Novel voltage and current source converter configurations, based on voltage and current reinjection concepts are proposed. These converter configurations are thoroughly analyzed in their ac and dc system sides. The fundamentals of the reinjection concept is discussed briefly, which lead to the derivation of the ideal reinjection waveform for complete harmonic cancellation and approximations for practical implementation. The concept of multi level voltage reinjection VSC is demonstrated through two types of configurations, based on standard 12-pulse parallel and series connected VSC modified with reinjection bridges and transformers. Firing control strategies and steady state waveform analysis are presented and verified by EMTDC simulations. The multi level current reinjection CSC is also described using two configurations based on standard 12-pulse parallel and series connected CSC modified with associated reinjection circuitry. Firing control strategies and steady state waveform analysis are presented and verified by EMTDC simulations. Taking the advantage of zero current switching in the main bridge valves, achieved through multi level current reinjection, an advanced multi level current reinjection scheme, consisting thyristor main bridges and self-commutated reinjection circuitry is proposed. This hybrid scheme effectively incorporates self-commutated capability into a conventional thyristor converter. The ability of the main bridge valves to commutate without the assistance of a turn-off pulse or line commutating voltage under the zero current condition is explained and verified by EMTDC simulations. Finally, the applications of the MLCR-CSC are discussed in terms of a back to back HVDC link and a long distance HVDC transmission system. The power and control structures and closed loop control strategies are presented. Dynamic simulation is carried out on PSCAD/EMTDC to demonstrate the two systems ability to respond to varying active and reactive power operating conditions.

Σκοπός της παρούσας εργασίας είναι η μελέτη, η προσομοίωση και η κατασκευή ηλεκτρονικού μετατροπέα ισχύος, για τη διασύνδεση με το ηλεκτρικό δίκτυο, πηγών ηλεκτρικής ενέργειας που προέρχονται από ανανεώσιμες μορφές, συγκεκριμένα από την ανεμογεννήτρια και το φωτοβολταϊκό σύστημα που είναι εγκατεστημένα στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας (Ε.Η.Μ.Ε). / This paper is about study, simulation, design and constraction electronic power converter to connect with the electric grid, sourses of electricity generated by renewable energy, specifically from wind and solar.

Η παρούσα διδακτορική διατριβή εντάσσεται στο πλαίσιο που αφορά στο πεδίο ελέγχου συστημάτων ισχύος και ειδικότερα στην εφαρμογή προηγμένων μεθόδων στην ανάλυση και τον έλεγχο στρεφόμενων ηλεκτρικών μηχανών οδηγούμενων από ηλεκτρονικές διατάξεις ισχύος. Ειδικότερα, λαμβάνοντας υπόψη τα ακριβή μη γραμμικά μοντέλα των μετατροπέων ισχύος και των ηλεκτρικών μηχανών, αναλύεται η μορφή και η συμπεριφορά των ολοκληρωμένων συστημάτων που χρησιμοποιούνται για την οδήγηση των μηχανών και αποδεικνύεται ότι τα μοντέλα αυτά μπορούν να περιγραφούν με τη γενική παθητική Hamiltonian μορφή. Οι ηλεκτρονικές διατάξεις ισχύος που μελετώνται είναι ο μετατροπέας ΣΡ/ΣΡ ανύψωσης τάσης και ο τριφασικός μετατροπέας σε λειτουργία ανορθωτή και μετατροπέα, ενώ επίσης μελετώνται οι μηχανές ΣΡ ξένης διέγερσης και με διέγερση σε σειρά καθώς επίσης και η τριφασική επαγωγική μηχανή. Έχοντας αναπτύξει τα πλήρη μοντέλα, προτείνεται ένας νέος μη γραμμικός νόμος ελέγχου κατάλληλος για τη γενική παθητική Hamiltonian μορφή των συστημάτων τα οποία περιλαμβάνουν διακοπτικούς μετατροπείς ισχύος. Μια εκτενής μη γραμμική μαθηματική ανάλυση αποδεικνύει ότι ο προτεινόμενος νόμος ελέγχου εγγυάται ευστάθεια και σύγκλιση στο επιθυμητό σημείο ισορροπίας για το σύστημα κλειστού βρόχου. Ο έλεγχος αυτός εφαρμόζεται για τον έλεγχο κινητήρων ΣΡ οδηγούμενων από μετατροπέα ΣΡ/ΣΡ ανύψωσης τάσης καθώς και στην τριφασική επαγωγική μηχανή. Η ανάλυση και η εφαρμογή του ελέγχου οδηγεί στην ανάγκη για επεκτάσεις στη μορφή του ώστε να αυξηθεί η σθεναρότητά του ως προς τις αρχικές συνθήκες, να βελτιωθεί η μεταβατική του συμπεριφορά και να εφαρμοστεί κατάλληλα σε τριφασικούς μετατροπείς ισχύος ώστε να εγγυάται συγκεκριμένες λειτουργίες όπως γραμμική διαμόρφωση. Με την εφαρμογή του ελέγχου στην επαγωγική μηχανή, προτείνεται μια πλήρης σχεδίαση που λειτουργεί είτε βασιζόμενη στη λογική του προσανατολισμένου πεδίου, είτε πλήρως ανεξάρτητα από αυτή, ενώ μελετάται και η συμπεριφορά του σε καταστάσεις εξασθένησης πεδίου. Τέλος, η λογική του ελέγχου επιβεβαιώνεται σε ένα σύστημα ανεμογεννήτριας συνδεδεμένης στο δίκτυο μέσω πλήρους συστήματος μετατροπέων ισχύος με διασύνδεση συνεχούς ρεύματος. Σε όλες τις περιπτώσεις παρουσιάζονται προσομοιώσεις και κατά το δυνατό πειραματικά αποτελέσματα μέσω κατάλληλων εργαστηριακών διατάξεων. / The present PhD dissertation is addressed in the research field of control of power systems and more precisely in providing advanced methods for the analysis and control of electrical machines driven by power devices. Particularly, taking into account the accurate nonlinear models of the power converters and the electrical machines, the structure and the behavior of the complete models used for machine driving are analyzed based on the generalized Hamiltonian-passive form. The power converters discussed are the DC/DC boost converter and the three-phase power converter used as a rectifier or an inverter, while the separately-excited and the series-connected DC motors along with the three-phase induction machine are studied as well. After providing the complete dynamic models, a new nonlinear control scheme suitable for the generalized Hamiltonian-passive systems with switching devices is proposed. Using an extended mathematical analysis, it is proven that the proposed controller guarantees stability and convergence to the desired equilibrium for the closed-loop system. The proposed control application is tested for DC drive systems fed by DC/DC boost converters as well as for induction motor systems fed by AC/DC/AC converters. The control analysis and application leads to the extension of the control structure in order to increase the robustness with respect to the initial conditions, to improve the transient performance and to be suitably applied in three-phase power converter systems, guaranteeing simultaneously certain operating constraints such as linear modulation. For the case of the induction motor control, a complete form of the controller is proposed that acts either in the frame of field-orientation or independently from it, while the controller is also studied in field-weakening conditions. Finally, the controller performance is studied in a wind generating system connected to the grid through a full-scale power converter. In all cases, simulation results are presented while experimental results are provided where possible by using suitable laboratory testbeds.

Dans nos travaux, nous nous intéressons à la commande des convertisseurs statiques à grand nombre d'interrupteurs. Le développement des topologies multi-niveaux multi-bras a ouvert l'accès aux domaines de la forte puissance et de la haute qualité harmonique. Outre cette montée en puissance, la commande spéciale de ces dispositifs permet de conférer au convertisseur des fonctionnalités avancées de plus en plus nécessaires, comme la possibilité de filtrage actif des harmoniques, la tolérance aux pannes, la gestion du réactif, les liaisons HVDC, etc. Toutefois, un plus grand nombre d'interrupteurs au sein d'une même structure de conversion se traduit par une forte croissance du nombre de variables de commande, des degrés de liberté et par une explosion combinatoire du nombre de configurations possibles. La synthèse de lois de commande suivant les approches traditionnellement conçues pour les topologies classiques, comme les méthodes de modulation vectorielle fondées sur la représentation géométrique du convertisseur, en devient rapidement fastidieuse pour les nouvelles topologies plus complexes. De plus, les interrupteurs présents en surnombre apportent des redondances fortes qui ne sont pas nécessairement exploitées, ou du moins arbitrairement. Nous proposons une nouvelle approche de commande qui se veut moins dépendante du nombre d'interrupteurs, et qui s'affranchit des limitations induites par les méthodes de modulation géométrique. Notre approche consiste dans un premier temps à formuler de manière algébrique des problèmes de commande qui sont généralement sous-déterminés, témoignant de la présence de redondances ou degrés de liberté, et contraints, car tenant compte des limitations propres aux rapports cycliques. De manière intéressante, ces problèmes offrent une similarité avec les problèmes dits d'allocation de commande rencontrés en aéronautique, en marine ou en robotique. Dans un second temps, dans le but de fournir à chaque période de découpage une solution de commande unique et optimisée, nous concevons de nouvelles méthodes d'allocation pour les convertisseurs statiques fondées sur l'optimisation numérique en ligne à partir de techniques d'optimisation linéaire. En conséquence, les rapports cycliques sont automatiquement optimisés pour satisfaire aux références de tension tout en respectant les saturations et en exploitant les redondances disponibles selon l'état actuel du convertisseur. Nous mettons en lumière les propriétés naturellement offertes par nos méthodes. Notamment, toutes nos solutions de modulation étendent de manière maximale la zone de linéarité du convertisseur. Nous proposons des méthodes d'allocation pour la commande en tension ou en courant de topologies variées : l'onduleur quatre bras deux niveaux, l'onduleur multicellulaire à condensateurs flottants, l'onduleur modulaire multi-niveaux. Concernant les convertisseurs multicellulaires, nos méthodes d'allocation utilisent automatiquement les degrés de liberté disponible pour fournir un équilibrage actif très rapide des tensions de condensateurs flottants. Aussi, grâce à la formulation algébrique des contraintes de commande, nos algorithmes peuvent prendre en compte un défaut sur un interrupteur pour conférer au convertisseur une propriété de tolérance aux fautes du point de vue de la commande. / In our works, we are interested in control of high-switch-count power converters. The development of multileg, multilevel converters has opened the access to high power and high harmonic quality. The special control of these devices brings to the converter advanced abilities that are more and more requested nowadays, like active harmonic filtering, fault tolerance, active and reactive power transfer, High Voltage Direct Current (HVDC) links, etc. However, a higher number of switches in a conversion structure leads to a higher number of control variables, as well as more redundancies and a combinatorial explosion of the number of possible configurations. The development of control laws resulting from approaches traditionally designed for classical topologies, as for space vector modulation methods, becomes harder for new, much complex topologies. Moreover, the too many available switches bring strong control redundancies that are not necessarily exploited, at least arbitrarily. We propose a new control approach that is expected to be less dependent on the number of switches, and that does not suffer from limitations proper to geometrical modulation methods. Firstly, our approach consists in the algebraic formulation of control problems that are generally under-determined, highlighting the presence of redundancies and degrees of freedom, and constrained, because control limitations are taken into account. Interestingly, a connection can be highlighted to the so-called control allocation problem in flight control, robotics, or marine applications. Secondly, in order to compute a unique and optimized control solution at each switching period, we develop new control allocation methods for power converters based on on-line numerical optimization using linear programming techniques. Consequently, duty cycles are automatically optimized to satisfy voltage references while respecting saturations and exploiting available redundancies depending on the state of the converter. We highlight the properties naturally offered by our methods. In particular, all modulation solutions yield a maximized extension of the linearity range of the converter. We propose control allocation methods for the voltage or current control of many topologies: the four-leg two-level inverter, the multicellular flying capacitor inverter, the modular multilevel inverter.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / In applications related to power converters, such as inverters, rectifiers and the use of active filters, the synchronization method represent a very important element in the performance of the control strategy of this equipment. The estimated values of the synchronism angle, frequency and amplitude determined by the synchronization algorithms present, facing strongly distorted signals with the presence of sub and interharmonics, high errors. This study presents two algorithms: one applied on single-phase electrical systems and one applied on three-phase electrical systems, with high immunity to interharmonics and subharmonics. First are presented the main synchronization systems that are used in the electrical power systems. In addition, will be presented the main causes and consequences of the presence of subharmonics and interharmnics in the system, as well as the mathematical modeling of the two algorithms with high rejection to these disturbances. Will be presented the simulation and the experimental results of the proposed algorithms and the comparison between these synchronization methods with particular methods present in the literature. As a result of the study, it can be seen that the proposed structures present a higher response time, but the error of the estimated signal with respect the fundamental component of the input signal is lower when compared to structures such as EPLL and structures based on SOGI. It was observed that the proposed synchronization methods are enabled to estimate the synchronism angle, the frequency and the fundamental component of the input signal adequately and can be used in control strategies of power converters. / Em aplicaÃÃes relacionadas à EletrÃnica de PotÃncia, como inversores, retificadores e a utilizaÃÃo de filtros ativos, o mÃtodo de sincronizaÃÃo representa um elemento chave no desempenho da estratÃgia de controle destes equipamentos. Os valores do Ãngulo de sincronismo, frequÃncia e amplitude estimados com determinados algoritmos de sincronizaÃÃo apresentam, diante de sinais fortemente distorcidos com a presenÃa de sub e inter-harmÃnicos, erros elevados. Neste trabalho sÃo apresentados dois algoritmos: um aplicado a sistemas elÃtricos monofÃsicos e outro aplicado a sistemas elÃtricos trifÃsicos, com elevada imunidade a inter-harmÃnicos e sub-harmÃnicos. Primeiramente sÃo apresentados os principais sistemas de sincronizaÃÃo utilizados em sistemas elÃtricos de potÃncia. AlÃm disso, sÃo apresentadas as principais causas e consequÃncias da presenÃa de sub-harmÃnicos e inter-harmÃnicos no sistema, bem como a modelagem matemÃtica dos dois algoritmos com elevada rejeiÃÃo a estes distÃrbios. SÃo apresentados os resultados de simulaÃÃo e experimentais dos algoritmos propostos e a comparaÃÃo entre estes mÃtodos de sincronizaÃÃo com determinados mÃtodos presentes na literatura. Como resultado do estudo, pode-se observar que as estruturas de sincronizaÃÃo propostas apresentam um tempo de resposta mais elevado, porÃm o erro do sinal estimado em relaÃÃo a componente fundamental do sinal de entrada à inferior quando comparado a estruturas como o EPLL e estruturas baseadas no SOGI. Com isso, tem-se que as mesmas estÃo habilitadas para estimar o Ãngulo de sincronismo, a frequÃncia e a componente fundamental do sinal de entrada adequadamente e podem serem utilizadas eficientemente em estratÃgias de controle de conversores de potÃncia.

Orientador: José Antenor Pomilio / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-23T00:46:30Z (GMT). No. of bitstreams: 1 Alvarenga_MarcosBalduinode_D.pdf: 18917931 bytes, checksum: a0630621c255135a8bf5fd49974daea6 (MD5) Previous issue date: 2013 / Resumo: Esta tese apresenta contribuições para o emprego de inversor multinível em cascata simétrica como filtro ativo de potência. O balanceamento das tensões nos barramentos CC é feito a partir de informação de um único bit obtido em cada módulo do conversor. O balanceamento é realizado através da postergação ou da supressão dos pulsos e, também, pela organização da ordem de acionamento das chaves semicondutoras de potência. A estratégia de modulação desenvolvida permite também a equalização dos pulsos de chaveamento entre os diversos módulos do inversor e suprime um porcentual de comutações redundantes ou irrelevantes, minimizando as perdas do conversor. Toma-se como parâmetro de qualidade a distorção harmônica decorrente de tais procedimentos. A técnica desenvolvida viabiliza a inserção de células em redundância, o que aumenta a confiabilidade da operação, favorecendo sua aplicação em filtros ativos de potência e dispositivos de condicionamento aplicados em redes de energia elétrica. O controle da corrente do filtro ativo e o controle das tensões nos barramentos CC são executados por dois controladores independentes, cujos projetos são detalhados e equacionados. A estratégia foi avaliada em um protótipo experimental de baixa tensão, constituído de um conversor multinível composto por quatro células simétricas, sendo uma em redundância, comandadas por um microcontrolador. Foram realizadas, também, simulações, considerando um alimentador de distribuição com 22,5 MVA e 13,8 kV. Nas análises dos resultados, são considerados os valores estabelecidos por normas relativas ao limite de harmônicas de corrente / Abstract: The present thesis shows contributions to the use of symmetrical cascaded multilevel inverter as active power filter. The balancing of the voltages on the DC bus is made from a single bit of information obtained in each converter module. Balancing is performed by postponement or suppression pulses and also for organizing the order of activation of the power semiconductor switches. The modulation strategy developed also allows the equalization of switching pulses between different inverter modules and removes a percentage of redundant or irrelevant switching, minimizing the losses of the converter. Taken as the quality parameter was the harmonic distortion resulting from such procedures. The technique developed enables the insertion of cells in redundancy, which increases reliability of the operation, in favor of their use in active power filters and conditioning devices used in power grids. The current control of active filter and control voltages in DC buses are performed by two independent controllers, whose projects are detailed and calculated. The strategy was evaluated in an experimental prototype low-voltage, consisting of a multilevel converter composed of four symmetrical cells, one redundancy, controlled by a microcontroller. It was also performed simulations considering a distribution feeder with 22.5 MVA and 13.8 kV. In the analysis of the results it was taken into account established values by standards for harmonic current limit / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

Orientador: José Antenor Pomilio / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T00:56:56Z (GMT). No. of bitstreams: 1 Pimentel_SergioPires_D.pdf: 7198764 bytes, checksum: 8dbb9a95a5a5374423051cba1bcfc1be (MD5) Previous issue date: 2011 / Resumo: Este trabalho aborda as características que envolvem o gerenciamento da operação de um sistema monofásico de geração distribuída. Embora tais características possam ser expandidas para sistemas trifásicos e de potência elevada, o sistema proposto está relacionado com aplicações de geração distribuída em baixa tensão ou naquelas que envolvam consumidores residenciais. O funcionamento do sistema proposto é baseado em um conversor eletrônico de potência elaborado a partir da estrutura multinível na topologia cascata assimétrica de 19 níveis. Nesta topologia, as tensões dos barramentos CC devem ser isoladas e desiguais entre si. Tal condição permite o envolvimento, nos barramentos CC do inversor, de múltiplas ou diferentes fontes alternativas de energia elétrica tais como sistemas fotovoltaicos, sistemas de células a combustível ou sistemas eólicos associados com conversores CC/CC. Com o sistema em operação, busca-se uma injeção apenas de potência ativa no sistema de distribuição alimentador e um fornecimento ininterrupto de energia elétrica para uma carga local mesmo quando nesta predominar características não-lineares de alimentação. Assim, de acordo com os seus objetivos, o sistema proposto opera de forma contínua e intercalada entre os modos ilhado e compartilhado. Detalhes sobre tais modos de operação e suas respectivas transições são apresentadas. As transições envolvem a detecção de ilhamento e o êxito no sincronismo. Em função disso, é apresentado um método ativo de detecção de condições de ilhamento. Tal método representa a adaptação de um método ativo já existente (AFDPF) aos requisitos de operação do sistema proposto neste trabalho. Justificativas e detalhes dessa adaptação do método ativo AFDPF são apresentados. Com relação à outra transição, um método de sincronismo baseado em técnicas PLL é apresentado. Tal método de sincronismo atende os requisitos estabelecidos em IEEE Std 1547-2003, diminuindo os impactos de uma possível religação com o sistema de distribuição. Para permitir um melhor funcionamento sob diferentes requisitos, também são descritas as etapas que envolvem os métodos de projeto dos controladores adotados: controlador PI de corrente de saída; controlador PI de potência média injetada; e controlador P+Ress de tensão na carga. Em especial, é apresentada uma nova metodologia de projeto do controlador proporcional e ressonante (P+Ress) de tensão baseada na sua resposta em malha fechada observada no domínio do tempo, em contrapartida ao seu método clássico de projeto baseado no domínio da freqüência. Um modelo matemático para simulações computacionais e um protótipo experimental utilizando o DSP TMS320F2812 foram considerados. Resultados de simulações computacionais e experimentais são comparados e permitem a verificação do comportamento do sistema proposto sob condições normais e anormais de operação / Abstract: This work regards the issues related to the operation management of a single-phase distributed generation system. Although these issues can be applied three-phase systems and high power systems, the proposed system is related to low voltage distributed generation applications or related to residential consumers. The operation of the single-phase proposed system is based on an utility-interactive power electronics converter which is composed by an asymmetrical cascaded multilevel inverter. This topology is able to create an output signal with up to 19 levels and it is supplied by DC voltage power sources that must be isolated and unequal from each other. By this demand it is possible to combine multiple and/or different alternative DC voltage power supplies as photovoltaic, fuel cells or wind energy systems into the DC buses of the single-phase multilevel inverter. During the operation of the proposed system, an injection of only active power into the grid utility and an uninterrupted load supply are achieved even when the local load (or group of local loads) has predominant nonlinear characteristics. For those reasons the proposed system operates continuously and alternately between two operation modes: grid-connected mode and stand-alone mode. Details about them and its transitions are also presented. The transitions are related to a correct detection of islanding situations and also to an effective synchronization method. The islanding detection is achieved by adaptations on an already known active method (AFDPF) to accomplish the project's goals. The reasons and details about these adaptations are presented. Furthermore the synchronization method is described and it is based on PLL techniques. Both transition methods meet the IEEE Std 1547-2003 requirements and it decreases the impacts from the proposed system into grid utility. To guarantee a suitable operating under several conditions, a wide range of operation points can be found by using the design methods described to each proposed controller: PI output current controller; PI injected active power controller; and a P+Ress load voltage controller. In highlights it is proposed a new design method to proportional and resonant controller (P+Ress) based on its closed-loop time response, instead of the classical method based on its open-loop frequency response. A mathematical model for simulations and an experimental low power prototype based on DSP TMS320F2812 have been considered. Simulation and experimental results are compared and they allow examining the performance of the proposed system operating under normal and abnormal conditions / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

Orientador: Ernesto Ruppert Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T00:56:13Z (GMT). No. of bitstreams: 1 Dias_AgnaldoVieira_M.pdf: 2229736 bytes, checksum: 725a7fa267bc30780c457689e4356336 (MD5) Previous issue date: 2012 / Resumo: O estudo da utilização de conversores CC/CC isolados e elevadores de tensão para a alimentação de moduladores de pulsos é apresentado neste trabalho. Foi selecionada a topologia em ponte completa, dando-se enfoque ao problema das capacitâncias parasitas envolvidas no circuito, que aparecem de forma acentuada em transformadores elevadores de tensão e filtros indutivos de saída e são altamente indesejáveis quando se opera em regime chaveado. Essas capacitâncias são tratadas através de uma forma de amortecimento, onde a energia armazenada nas mesmas é devolvida à fonte primária ao final de cada semiciclo de chaveamento, tentando obter-se menor volume, maior rendimento e menor dissipação de calor no conversor. Além disso, um circuito de regulação de carga é utilizado para garantir uma maior estabilidade de pulso e contornar problemas típicos de moduladores de pulsos utilizados em radares, como o efeito de backswing. O modulador de pulsos utilizado como carga para esse sistema opera com uma tensão de alimentação de 1kV, frequência de repetição de pulsos (PRF) de 585Hz e consome uma potência da ordem de 2,1kW. O conversor CC/CC é alimentado por um barramento CC não regulado de 280V / Abstract: The study of high-voltage isolated DC/DC converters used to supply pulse modulators is presented on this dissertation. The Full Bridge topology was selected, focusing in problems caused by parasitic capacitances in the circuit. This characteristic, which appears sharply in high voltage transformers and in inductors of output filter, is highly undesirable when the circuit is operated in switching mode. These capacitances are handled using a soft commutation technique, where their stored energy are returned to the primary source in the end of each switching cycle, trying to get a low size, high efficiency and low heat dissipation in the converter. Moreover, a charging regulator circuit is used to ensure good pulse stability and avoid typical problems in the pulse modulators use, such as the backswing effect. The pulse modulator used as load for this converter operates with a supply voltage of 1kV, pulse repetition frequency (PRF) of 585Hz and consumes 2.1 kW. The converter input is supplied by a 280V unregulated DC bus / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica