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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Έλεγχος στροφών επαγωγικής μηχανής δακτυλιοφόρου δρομέα διπλής τροφοδοσίας : μια εναλλακτική προσέγγιση

Βαγγέλης, Φώτιος 05 March 2012 (has links)
Στην παρούσα διπλωματική εργασία παρουσιάζεται μια νέα προσέγγιση της επαγωγικής μηχανής δακτυλιοφόρου δρομέα που χρησιμοποιείται σε συστήματα ανεμογεννητριών. Αρχικά γίνεται μια σύντομη παρουσίαση των ανανεώσιμων πηγών ενέργειας και ειδικότερα της αιολικής ενέργειας. Παρουσιάζονται τα είδη των ανεμογεννητριών και τα συστήματα κινητήρων που χρησιμοποιούνται σε αυτές και ακολουθεί η ταξινόμηση, η ανάλυση και ο διανυσματικός έλεγχος του μετατροπέα προς την πλευρά του δικτύου και προς την πλευρά του δρομέα της επαγωγικής γεννήτριας διπλής τροφοδοσίας (DFIG). Τέλος μελετάται μια εναλλακτική προσέγγιση της επαγωγικής μηχανής ελεγχόμενου δρομέα και στάτη από τριφασικό μετατροπέα και ακολουθεί η προσομοίωση των εξισώσεων του συστήματος με τη βοήθεια του Matlab. / This thesis presents a new approach of the wound rotor induction machine used in wind turbine systems. First we make a brief presentation of renewable energies and especially of the wind energy. We present the kinds of wind turbines and engine systems used in them, followed by classification, analysis and vector control of the inverter on the side of the grid and to the side of the rotor of double fed induction generator (DFIG). Finally, we study an alternative approach of the induction machine controlled by rotor and stator of a three-phase converter, followed by the simulation of the equations of the system with the help of Matlab.
2

Sensorlose Regelung der Asynchronmaschine zur aktiven Schwingungsdämpfung

Warschofsky, André 22 December 2016 (has links) (PDF)
Die Dissertation stellt Regelverfahren für die Asynchronmaschine mit Kurzschlussläufer und die doppeltgespeiste Asynchronmaschine vor, die Torsionsschwingungen im Antriebsstrang über einen Eingriff am Luftspaltmoment dämpfen und ohne Sensoren für die Drehzahl, den Drehwinkel und das Drehmoment arbeiten. Alle für die Regelverfahren benötigten Zustandsgrößen der Asynchronmaschine und des mechanischen Systems werden mit Beobachtern aus den gemessenen Spannungs- und Stromkomponenten geschätzt. Die Qualität der geschätzten Zustandsgrößen wird mit Gütekriterien bewertet und kann als durchweg gut bezeichnet werden. Die Regelverfahren werden bei der praktischen Erprobung mit Gütekriterien bezüglich der stationären Genauigkeit und im dynamischen Betrieb bezüglich der Schädigung und der Dynamik untersucht. Die Untersuchungen zeigen, dass die vorgestellten Maßnahmen zur Torsionsschwingungsdämpfung die Schädigung deutlich reduzieren. Die Ergebnisse zeigen zudem, dass bei Verwendung geschätzter statt gemessener Zustandsgrößen für die Regelverfahren kaum Einbußen bezüglich der stationären Genauigkeit, der Dynamik und der Reduzierung der Schädigung entstehen. Für das Regelverfahren der doppeltgespeisten Asynchronmaschine wird simulativ nachgewiesen, dass dieses auch beim Netzspannungseinbruch stabil arbeitet.
3

Controle do fluxo de potencia da maquina de indução duplamente alimentada / Control of the power flux of the doubly fed induction machine

Segnini, Helio Henrique de Agostini 17 March 2006 (has links)
Orientador: Edson Bim / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T02:49:03Z (GMT). No. of bitstreams: 1 Segnini_HelioHenriquedeAgostini_M.pdf: 1646244 bytes, checksum: d03ec95486ccbccae70ffedf89d964f1 (MD5) Previous issue date: 2006 / Resumo: O objetivo deste trabalho é estudar o modelo da máquina de indução duplamente alimentada no sistema de referência síncrono, bem como controlar seu fluxo de potências através de orientação de fluxo. São analisadas as orientações de fluxo de estator, de entreferro e de rotor em várias operações: compensador de reativos, gerador e motor, com fator de potência indutivo, capacitivo e unitário, nas faixas de velocidade subsíncrona, síncrona e supersíncrona / Abstract: The purpose of this work is to study the Doubly Fed Induction Machine modeling at the synchronous reference frame, as well as to control its power flux by flux oriented control The stator, rotor and air gap flux orientations with the machine operating as reactive compensator, generator and drive, with lag power factor, lead power factor and unity power factor at subsynchronous, synchronous and supersynchronous speeds are analyzed. / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica
4

Controle sensorless do gerador de indução duplamente alimentado operando com afundamentos de tensão / Sensorless control of doubly fed induction generator operating with voltage sags

Jacomini, Rogério Vani 10 November 2012 (has links)
Orientador: Edson Bim / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T12:34:50Z (GMT). No. of bitstreams: 1 Jacomini_RogerioVani_D.pdf: 15030828 bytes, checksum: 7c0af103e9c6a3a9527e3c25e4373e7e (MD5) Previous issue date: 2012 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica
5

Estimation and diagnostic of doubly-fed asynchronous wind generator / Estimation et diagnostic de la machine asynchrone à double alimentation dans le système éolienne

Vu, Hoang Giang 18 July 2014 (has links)
Dans ce mémoire de thèse nous présentons une méthodologie pour le diagnostic et la surveillance en ligne des éoliennes de l'état de l'ensemble machine électrique onduleur à partir de la mesure du champ magnétique continu. Ce travail est scindé en deux parties complémentaires. Dans la première partie, nous donnons quelques contributions concernant l'estimation de l'état et des paramètres pour certaines classes de systèmes non linéaires. Ces mêmes estimateurs ont été validés en simulation et sur un banc d'essai. La deuxième partie porte sur la mise en œuvre et la conception de deux bancs d'essai utilisés pour l'étude des défauts dans un système double alimentation MADA et un ensemble moteur électrique onduleur classique pour l'analyse des défauts du convertisseur. L'identification des paramètres et la technique de contrôle du système en boucle fermé est introduite pour l'application MADA. De plus, les capteurs virtuels sont conçus pour estimer la vitesse mécanique qui est utilisée pour calculer les fréquences caractéristiques défectueuses, et le signal de couple mécanique qui exerce une influence sur l'amplitude de certaines des signatures défectueux typiquement. Finalement, sur la base de la mise en équation théorique des signaux électriques avec défauts puis des simulations correspondantes, une comparaison avec l'expérimentation est réalisée pour valider la technique proposée. Ces travaux montrent l'avantage d'une telle technique dans la simplicité de l'instrumentation mis en œuvre / This doctoral thesis presents a methodology for the online condition monitoring of the electrical power drive in wind energy systems based on the local measurement of the DC-bus magnetic field. The work is divided into two complementary parts. In the first part, some contributions related to the estimation of the state and parameters for certain classes of nonlinear systems are provided. The estimators have been validated in simulation and on test benches. The second part focuses on the implementation and control design of two benchmarks used to study defects in a doubly-fed induction generator (DFIG) system and an induction motor power drive. In the former benchmark, the parameters identification of the induction machine and the controller design of the DFIG system are carried out. For the latter test bench, the notable work is to build an induction machine drive for the purpose of fault investigation, in which a PWM generator is developed to control and create the fault of the converter. Furthermore, virtual sensors are designed to estimate mechanical speed that is used to calculate the characteristic frequencies, and mechanical torque signal that has influence on the amplitude of some typical fault signatures. Finally, based on the theoretical aspect of the selected faults, the relevant simulations are developed and experiments are implemented on the benchmarks in order to validate the proposed technique. It has been shown that the diagnostic relying on the magnetic field measurement is feasible and offers various advantages such as simplicity and cost-effectiveness
6

Sensorlose Regelung der Asynchronmaschine zur aktiven Schwingungsdämpfung

Warschofsky, André 13 October 2016 (has links)
Die Dissertation stellt Regelverfahren für die Asynchronmaschine mit Kurzschlussläufer und die doppeltgespeiste Asynchronmaschine vor, die Torsionsschwingungen im Antriebsstrang über einen Eingriff am Luftspaltmoment dämpfen und ohne Sensoren für die Drehzahl, den Drehwinkel und das Drehmoment arbeiten. Alle für die Regelverfahren benötigten Zustandsgrößen der Asynchronmaschine und des mechanischen Systems werden mit Beobachtern aus den gemessenen Spannungs- und Stromkomponenten geschätzt. Die Qualität der geschätzten Zustandsgrößen wird mit Gütekriterien bewertet und kann als durchweg gut bezeichnet werden. Die Regelverfahren werden bei der praktischen Erprobung mit Gütekriterien bezüglich der stationären Genauigkeit und im dynamischen Betrieb bezüglich der Schädigung und der Dynamik untersucht. Die Untersuchungen zeigen, dass die vorgestellten Maßnahmen zur Torsionsschwingungsdämpfung die Schädigung deutlich reduzieren. Die Ergebnisse zeigen zudem, dass bei Verwendung geschätzter statt gemessener Zustandsgrößen für die Regelverfahren kaum Einbußen bezüglich der stationären Genauigkeit, der Dynamik und der Reduzierung der Schädigung entstehen. Für das Regelverfahren der doppeltgespeisten Asynchronmaschine wird simulativ nachgewiesen, dass dieses auch beim Netzspannungseinbruch stabil arbeitet.
7

Estratégias para identificação de faltas externas e controle do gerador de indução duplamente alimentado / Strategies for fault intentification and control of the doubly fed induction generator

Santana, Marcelo Patrício de 31 July 2012 (has links)
O presente trabalho desenvolve uma topologia de controle para o gerador de indução duplamente alimentado (GIDA) em condições normais e em condições de falta monofásica. O sistema de controle é dividido em três partes principais: sistema de identificação de faltas, controle em condições normais e controle em condições de falta monofásica. A primeira parte, o sistema de identificação (SI) de faltas, é responsável pela seleção da topologia de controle da máquina. O SI é composto por uma combinação entre redes neurais artificiais (RNA) e a Fast Fourier Transform (FFT). As RNA são responsáveis pela identificação do estado atual da rede, se possui falta ou não. Os dados de entrada das RNA são as correntes de linha do estator que passam por um pré-processamento por meio da FFT. Alguns conteúdos harmônicos de saída da FFT irrelevantes no processo de identificação são eliminados por um método similar ao Principal Components Analysis (PCA). A segunda parte do trabalho é o controle em condições normais, sendo ativado quando o SI aponta a ausência de faltas. A topologia de controle vetorial é utilizada nesta condição para manter a tensão e frequência constante com a velocidade mecânica do eixo variável. A última parte do trabalho é o controle em condições adversas, que é ativado quando o SI detecta uma falta monofásica. A topologia de controle nesta condição utiliza as transformações ortogonais para reduzir o fluxo concatenado no enrolamento do estator com falta. A utilização deste novo controle reduz a corrente do estator quando comparado com o controle vetorial em condições de falta, sendo que a tensão do estator nas fases sem falta é mantida dentro de uma faixa de operação. O trabalho possui resultados de simulação das três principais partes do sistema de controle. Primeiramente, resultados do controle vetorial de tensão e frequência do GIDA sob condições de velocidade do eixo variável e cortes de carga são apresentados. Logo após, apresenta-se os resultados do SI na identificação de faltas monofásicas na fase B e o seu comportamento sob condições adversas como desequilíbrio de carga e cortes de cargas. Finalmente, alguns resultados do controle em condições de falta sobre uma falta fase-neutro na fase B são apresentados. / This paper presents a control topology for doubly fed induction generator (DFIG) in normal and single fault conditions. The control system is divided into three main parts: fault identification system, control in normal condition and control in single fault conditions. In the first part, the system of identification (SI) is responsible for selecting the topology of the control. The SI is composed by a combination of artificial neural networks (ANN) and Fast Fourier Transform (FFT). The ANN is responsible for identifying the current state of the grid, if has fault or not. The inputs of the ANN are stator currents line through of a pre-processing by means of FFT. Some harmonic contents are irrelevant in the identification process and they are eliminated by a method similar to Principal Components Analysis (PCA). The second part of the paper is the control under normal conditions, activated when the SI indicates the absence of faults. The topology of vector control in this condition is used to maintain the voltage and frequency constant, where the speed of the mechanical axis variable. The last part of the work is the control in adverse conditions, which is activated when the SI detects a singlephase fault. The control topology in this condition uses the orthogonal transformations to reduce the mutual flux in the stator winding with fault. The use of this new control reduces the stator current as compared to vector control in fault conditions, and the stator voltage in the stages without fault is maintained within an operating range. The paper has simulation results of three main parts of the control system. First, the results of the vector control voltage and frequency of DFIG under conditions of variable shaft speed and load sections are provided. Soon after, the results of the SI in identifying faults in the phase B under conditions such as load imbalance and cutting loads are shown. Finally, some results of control in fault condition in the phase B are shown.
8

Estratégias para identificação de faltas externas e controle do gerador de indução duplamente alimentado / Strategies for fault intentification and control of the doubly fed induction generator

Marcelo Patrício de Santana 31 July 2012 (has links)
O presente trabalho desenvolve uma topologia de controle para o gerador de indução duplamente alimentado (GIDA) em condições normais e em condições de falta monofásica. O sistema de controle é dividido em três partes principais: sistema de identificação de faltas, controle em condições normais e controle em condições de falta monofásica. A primeira parte, o sistema de identificação (SI) de faltas, é responsável pela seleção da topologia de controle da máquina. O SI é composto por uma combinação entre redes neurais artificiais (RNA) e a Fast Fourier Transform (FFT). As RNA são responsáveis pela identificação do estado atual da rede, se possui falta ou não. Os dados de entrada das RNA são as correntes de linha do estator que passam por um pré-processamento por meio da FFT. Alguns conteúdos harmônicos de saída da FFT irrelevantes no processo de identificação são eliminados por um método similar ao Principal Components Analysis (PCA). A segunda parte do trabalho é o controle em condições normais, sendo ativado quando o SI aponta a ausência de faltas. A topologia de controle vetorial é utilizada nesta condição para manter a tensão e frequência constante com a velocidade mecânica do eixo variável. A última parte do trabalho é o controle em condições adversas, que é ativado quando o SI detecta uma falta monofásica. A topologia de controle nesta condição utiliza as transformações ortogonais para reduzir o fluxo concatenado no enrolamento do estator com falta. A utilização deste novo controle reduz a corrente do estator quando comparado com o controle vetorial em condições de falta, sendo que a tensão do estator nas fases sem falta é mantida dentro de uma faixa de operação. O trabalho possui resultados de simulação das três principais partes do sistema de controle. Primeiramente, resultados do controle vetorial de tensão e frequência do GIDA sob condições de velocidade do eixo variável e cortes de carga são apresentados. Logo após, apresenta-se os resultados do SI na identificação de faltas monofásicas na fase B e o seu comportamento sob condições adversas como desequilíbrio de carga e cortes de cargas. Finalmente, alguns resultados do controle em condições de falta sobre uma falta fase-neutro na fase B são apresentados. / This paper presents a control topology for doubly fed induction generator (DFIG) in normal and single fault conditions. The control system is divided into three main parts: fault identification system, control in normal condition and control in single fault conditions. In the first part, the system of identification (SI) is responsible for selecting the topology of the control. The SI is composed by a combination of artificial neural networks (ANN) and Fast Fourier Transform (FFT). The ANN is responsible for identifying the current state of the grid, if has fault or not. The inputs of the ANN are stator currents line through of a pre-processing by means of FFT. Some harmonic contents are irrelevant in the identification process and they are eliminated by a method similar to Principal Components Analysis (PCA). The second part of the paper is the control under normal conditions, activated when the SI indicates the absence of faults. The topology of vector control in this condition is used to maintain the voltage and frequency constant, where the speed of the mechanical axis variable. The last part of the work is the control in adverse conditions, which is activated when the SI detects a singlephase fault. The control topology in this condition uses the orthogonal transformations to reduce the mutual flux in the stator winding with fault. The use of this new control reduces the stator current as compared to vector control in fault conditions, and the stator voltage in the stages without fault is maintained within an operating range. The paper has simulation results of three main parts of the control system. First, the results of the vector control voltage and frequency of DFIG under conditions of variable shaft speed and load sections are provided. Soon after, the results of the SI in identifying faults in the phase B under conditions such as load imbalance and cutting loads are shown. Finally, some results of control in fault condition in the phase B are shown.
9

Modeling and Analysis of Grid Connected Variable Speed Wind Generators

Seshadri Sravan Kumar, V January 2015 (has links) (PDF)
The growing demand for power and increased environmental concerns gave an impetus to the growth of clean and renewable energy sources like wind, solar etc. There is a remarkable increase in the penetration of wind energy systems in the last decade and this trend is bound to increase at a much faster pace in future. This ever increasing penetration of wind power generating systems pose multi-fold challenges related to operational and stability aspects of the grid. Present day wind energy systems mostly comprise of variable speed wind generators. A large fraction of present day variable speed wind turbine generators use doubly fed induction machine (DFIM). This thesis deals with modeling and grid coordination aspects of variable speed wind gener- ators. In particular, the short coming of the existing steady state equivalent circuit of a DFIM is identified and subsequently, an accurate equivalent circuit of a DFIM is proposed. Relevant mathematical basis for the proposed model is presented. The proposed steady state equivalent circuit of a doubly fed induction machine is further validated using dynamic simulations of a standalone machine. Based on the proposed equivalent circuit, two approaches for computing the initial values of state variables of a DFIM is proposed. The first approach is a linear formulation where the losses due to resistance of the stator and rotor windings are neglected. The second approach is a non-linear formulation which takes the losses into consideration. Further, analysis is carried out on grid connected doubly fed induction generators (DFIG). A framework to incorporate DFIG based variable speed wind farms in the steady state power flow analysis is proposed. The proposed framework takes into consideration important aspects such as voltage dependent reactive power limits and mode of reactive power control of associated converters. Some of the challenges in a grid connected DFIG especially during su- persynchronous mode of operation are identified. The advantages of a non-Maximum Power Point Tracking (MPPT) mode of operation under certain operating conditions is highlighted. Finally, aspects pertaining to coordination of grid connected variable speed wind generators are studied. A trust region framework to determine the reference values to the control loops of converters in a variable speed wind generator is proposed. The proposed framework identifies the reference values considering other reactive power controllers in the grid. Moreover, the proposed framework ensures that the steady state voltage stability margin is maximized. On the computational front, trust region algorithms ensure global convergence. The mathematical models and initialization algorithms proposed in this thesis are tested on standalone systems under various control scenarios. The algorithms proposed to incorporate a grid connected DFIG in steady state analysis tools have been tested on a sample 6-bus system and a practical 418-bus equivalent system of Indian southern grid.
10

Supervision d’une ferme éolienne pour son intégration dans la gestion d’un réseau électrique, Apports des convertisseurs multi niveaux au réglage des éoliennes à base de machine asynchrone à double alimentation / Management of a wind farm and integration in the operational power system, Contribution of multilevel power electronic converters for the control of doubly fed induction machine based wind generators

Ghennam, Tarak 29 September 2011 (has links)
La première thématique développée dans ce mémoire vise à développer de nouveaux algorithmes pour la commande des éoliennes reposant sur une machine asynchrone à double alimentation et des convertisseurs multi niveaux. Deux stratégies de contrôle direct du courant, basées sur l’Hystérésis à Zones Carrées et l’Hystérésis à Zones Circulaires (HZCi) ont été proposées. Celles-ci consistent à appliquer des vecteurs de tension appropriés pour contrôler les puissances actives et réactive générées et permettent également d’équilibrer les tensions du bus continu interne des convertisseurs. Des résultats de simulation et d’expérimentation montrent que la stratégie basée sur l’HZCi est meilleure en termes de forme d’onde et de contenu harmonique des tensions de sortie.La seconde concerne la supervision et la gestion des puissances active et réactive dans une ferme éolienne au vu de son intégration dans un réseau électrique. Cette supervision centralisée est assurée par un algorithme qui distribue les consignes de puissance aux éoliennes de la ferme de manière proportionnelle. Ces références sont fonction de la capacité maximale de production de l’éolienne. Pour cela, une analyse des transits de puissance dans le système éolien à base de la machine asynchrone à double alimentation a été effectuée. Elle a permis de déterminer la caractéristique (P, Q) du générateur et de calculer ses limites de compensation en termes de puissance réactive. Une gestion locale des puissances de chaque éolienne a été développée permettant ainsi une répartition des puissances entre le stator de la machine et le convertisseur coté réseau en considérant plusieurs modes de fonctionnement du système éolien / This research work deals with two topics conditioning the large scale development of wind turbines into electrical grids. The first is devoted to the development of new algorithms for the control of Doubly Fed Induction Machine (DFIM) based wind energy conversion systems. Two direct current control strategies have been proposed and are based on the hysteresis square areas (HZCA) and hysteresis circular areas (HZCI). Both strategies apply an appropriate voltage vector to control the active and reactive powers delivered to the grid, and also, to balance the voltages of the inner DC bus converter. Simulation and experimental results show that the HZCI strategy is better than HZCA in terms of output voltage waveforms and harmonic contain.The second topic is dedicated to the active and reactive powers supervision in a wind farm in order to supply prescribed power references from the grid operator. This supervision is ensured by a centralized algorithm that distributes power references between wind turbines in a proportional way. These references are calculated according to the maximum production capacity of wind turbines. An analysis of the power flow in the DFIM based wind energy system has been made to identify the (P, Q) characteristic and to calculate limits in terms of reactive power compensation. The local power management of each wind system has been developed allowing the powers distribution between the stator of the DFIM and the grid side converter by considering several operating modes of the wind generator

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