This thesis report describes the modeling procedure for available the wind turbine generator (WTG) technologies. The models are generic in nature and manufacturer independent. These models are implemented on commercially available dynamic simulation software platforms like PSCAD/EMTDC and MATLAB/SIMULINK. A brief introduction to the available WTG types is provided to understand the technological differences and their key features. The related theoretical concepts to the working of a WTG are explained, which acts as an aid for model development and implementation. Using the theoretical concepts as basis, a WTG model is divided into four parts : 1. Aerodynamic model 2. Mechanical drive train model 3. Electrical machine model 4. Controller model Once the different parts of a WTG are introduced, a groundwork for model implementation on the software platforms is laid. A step-by-step process of implementing a PSCAD or MATLAB model of a WTG is introduced in this thesis. Starting with the most fundamental WTG technology such as fixed-speed also known as direct-connect wind turbine. The model implementation is adanvced to other superior technology like the dynamic rotor resistance control (DRR) and the doubly-fed induction generator (DFIG). To better understand the working of a DFIG, a current-source regulated model (without electrical machine) emulating the DFIG is built on both PSCAD and MATLAB. A full blown converter model of the DFIG with back-to-back converter is then built in PSCAD/EMTDC. An approach to determine the reactive power capability (Q limits) of a DFIG is described. Rotor current limitation and stator current limitation of the DFIG are considered in determining the minimum and maximum reactive power delievered by the DFIG. Variation in the Q limits of a DFIG for change in wind speed is analysed with two different wind speed scenarios. 1. Wind speed from cut-in to rated i.e. 6 m/s - 14 m/s. 2. Wind speed above rated to cut-out i.e. 14 m/s - 20 m/s. Such an analysis, is useful in determining the operating mode of the DFIG. At low wind speeds (below rated), the DFIG can be operated as a STATCOM for exporting and importing reactive power (similar to synchronous machines). While above rated wind speeds, the DFIG can be set to produce maximum active power. Using the DFIG current-source model implemented in MATLAB/SIMULINK, laboratory experiments to plot the power profile of the DFIG is explained. Another experiment to perform independent P-Q control of the DFIG is also included in this report. / text

Les systèmes éoliens seront certainement amenés, à court terme, à contribuer aux services systèmes (compensation de la puissance réactive, stabilité du plan de tension,…) comme le font actuellement les alternateurs de centrales classiques. Ils seront également amenés à participer à l'amélioration de la qualité de l'énergie électrique, filtrage des courants harmoniques en particulier. De plus, vu l'augmentation de la puissance éolienne installée et fournie au réseau électrique, les éoliennes devront certainement assurer, à plus long terme, une continuité de service suite à un défaut électrique sur le réseau ou sur un des éléments de la chaîne de conversion électromécanique (interrupteurs de puissance, capteurs,…) afin d'améliorer leur fiabilité. Dans ces travaux de thèse, nous avons montré dans un premier temps qu'un système éolien basé sur une Machine Asynchrone à Double Alimentation (MADA) possédant un gain d'amplification entre les courants rotoriques et statoriques peut participer efficacement à l'amélioration de la qualité de l'énergie électrique en compensant simultanément de la puissance réactive et des courants harmoniques présents sur le réseau, sans pour autant nécessiter un surdimensionnement des éléments de la chaîne de conversion électromécanique. Ensuite, nous avons étudié des topologies dites “fault tolerant” de convertisseurs statiques triphasés et leurs commandes associées, permettant de garantir la continuité de service en présence de défauts éventuels d'un semi-conducteur ou d'un capteur de courant. Pour réduire autant que possible le temps de détection de défaut, nous avons ciblé un composant FPGA (Field Programmable Gate Array) pour le contrôle/commande “fault tolerant”. Les résultats de simulation, de prototypage “FPGA in the loop” et expérimentaux démontrent les performances des méthodes proposées / Wind Energy Conversion Systems (WECS) will probably be intended, in a short term, to provide ancillary services such as reactive power compensation, as done by conventional generators of power plants and/or participate in improving electric power quality by filtering harmonic currents. Furthermore, by considering the increased installed wind power, connected to the grid, WECS will certainly ensure, in long term, the continuity of service following an electrical fault on the grid or on one of elements of the electromechanical conversion (power switches, sensors…) to ensure their reliability. In this thesis, we have studied in the first part a WECS based on Doubly Fed Induction Generator (DFIG) with an amplification gain between the stator and rotor currents. We have demonstrated that such a WECS can efficiently improving the electric power quality by compensating simultaneously reactive power and harmonic currents on the grid, without requiring any oversized elements in the electromechanical conversion chain. Then, we studied fault tolerant converter topologies and associated controls, ensuring the continuity of service in the presence of possible faults of a semiconductor or a current sensor. To minimize the time fault detection, we used an FPGA (Field Programmable Gate Array) to implement the fault tolerant controller. Simulation, “FPGA in the loop” prototyping and experimental results have validated the performances of the proposed methods and fault tolerant topologie

Στην παρούσα διπλωματική γίνεται ανάλυση και μοντελοποίηση ενός φωτοβολταϊκού και ενός αιολικού συστήματος συνδεμένα στο δίκτυο. Το φωτοβολταϊκό σύστημα θα αποτελείται απο 400 πλαίσια συνδεμένα μεταξύ τους, έναν μετατροπέα ανύψωσης της συνεχούς τάσης που βγάζουν τα φωτοβολταϊκά στην έξοδό τους και έναv αντιστροφέα που μετατρέπει την συνεχή τάση σε εναλλασσόμενη. Το αιολικό σύστημα αποτελείται απο μια ανεμογεννήτια, μια επαγωγική μηχανή διπλής τροφοδοσίας (DFIG), έναν ανορθωτή που μετατρέπει την εναλλασσόμενη τάση που δίνει στην έξοδό της η μηχανή σε συνεχή, και έναν αντιστροφέα που μετατρέπει την τελετυαια τάση σε εναλλασσόμενη. Στα συστήματα αυτά θα εφαρμόσουμε μια κατάλληλη στρατηγηκή ελέγχου, προκειμένου να έχουμε την μέγιστη παραγωγή ισχύος. Στο παραπάνω σύστημα θα αναλύσουμε θεωρητικά τη λειτουργία του και στη συνέχεια θα το προσωμοιώσουμε μέσω του Simulink του MATLAB. / This thesis is an analysis and modeling of a PV and a wind system connected to the network. The photovoltaic system consists of 400 panels connected together, a dc boost converter and an inverter. The wind system consists of a double fed induction generator (DFIG), a rectifier, and an inverter. These systems will implement the appropriate control in order to have the maximum power output. We will theoretically analyze the function of the above system and then the simulate it's operation through MATLAB's Simulink.

Η παρούσα διπλωματική εργασία πραγματεύεται την ανάλυση και τον σχεδιασμό έλεγχο ενεργού και αέργου ισχύος επαγωγικής γεννήτριας διπλής τροφοδοσίας (Doubly-Fed Induction Generator, DFIG), που χρησιμοποιείται σήμερα κατά κόρον σε συστήματα ανεμογεννητριών. Ο έλεγχος επιτυγχάνεται μέσω του διανυσματικού ελέγχου με προσανατολισμό στην τάση του δικτύου (Voltage-Oriented Control, VOC χρησιμοποιώντας αναλογικο-ολοκληρωτικούς (Proportional-Integral, PI) ελεγκτές, επιβάλλοντας με αυτόν τον τρόπο την επιθυμητή μεταβατική συμπεριφορά. / The following diploma thesis addresses the analysis and design of an active and reactive power control system for a Doubly-Fed Induction Generator (DFIG), vastly used in wind power systems. Control is being achieved under voltage orientation (Voltage-Oriented Control, VOC) and through the use of proportional-integral (PI) controllers, who impose the desirable transient behavior.

Η παρούσα εργασία πραγματεύεται την ανάλυση και τον έλεγχο της διπλά τροφοδοτούμενης επαγωγικής μηχανής (DFIG) που χρησιμοποιείται σε συστήματα ανεμογεννητριών. Στα πρώτα κεφάλαια θα αναφερθούν κάποια στοιχεία απαραίτητα για την κατανόηση του αντικειμένου και των προβλημάτων του και ακολουθεί η ενασχόληση με την επαγωγική γεννήτρια διπλής τροφοδοσίας. Αφού αναλυθεί η μηχανή εξάγονται οι εξισώσεις λειτουργίας αυτής και του μετατροπέα και, τέλος, εφαρμόζονται οι απαραίτητοι έλεγχοι για την επίτευξη της επιθυμητής συμπεριφοράς της μηχανής σε διαφορετικές συνθήκες λειτουργίας. / The present thesis is about analysis and control of a double-fed generator for wind generators.

Submitted by Maykon Nascimento (maykon.albani@hotmail.com) on 2015-11-16T18:15:13Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Avaliacao do limitador supercondutor resistivo no elo-CC do DFIG para suportabilidade a afundamentos de tensao.pdf: 2595378 bytes, checksum: 555c76d8ac8053bf86c8ee4bdb825fe0 (MD5) / Approved for entry into archive by Morgana Andrade (morgana.andrade@ufes.br) on 2016-01-07T11:06:00Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Avaliacao do limitador supercondutor resistivo no elo-CC do DFIG para suportabilidade a afundamentos de tensao.pdf: 2595378 bytes, checksum: 555c76d8ac8053bf86c8ee4bdb825fe0 (MD5) / Made available in DSpace on 2016-01-07T11:06:01Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Avaliacao do limitador supercondutor resistivo no elo-CC do DFIG para suportabilidade a afundamentos de tensao.pdf: 2595378 bytes, checksum: 555c76d8ac8053bf86c8ee4bdb825fe0 (MD5) Previous issue date: 2015 / CNPQ / Em um contexto de necessidade de aumento da oferta de energia elétrica e de busca por fontes renováveis e limpas de energia, a energia eólica tem experimentado um crescimento expressivo nos últimos anos. Uma das tecnologias mais empregadas em geradores eólicos, o DFIG, possui como maior susceptibilidade os distúrbios da rede, principalmente o afundamento de tensão. Soluções na topologia e no controle do gerador têm sido propostas para aumento da suportabilidade do gerador a esses fenômenos. Este trabalho avalia a utilização de um limitador de corrente supercondutor resistivo no elo-CC do conversor back-to-back para proteção do conversor e aumento da suportabilidade a afundamentos de tensão em um gerador eólico baseado em DFIG. A aplicação da tecnologia de supercondutores na proteção de sistemas eólicos é recente e os resultados obtidos nesse trabalho contribuem com os estudos feitos na área. Com o gerador DFIG operando em condições normais, o supercondutor não transita para o estado condutor, e permanece invisível à operação. Na ocorrência de um afundamento de tensão na rede a corrente no circuito de rotor aumenta ultrapassando o valor da corrente crítica e levando o supercondutor ao estado condutor, inserindo um elemento resistivo, limitando assim, a corrente. As análises são feitas utilizando o software de simulação de transitórios eletromagnéticos PSCAD/EMTDC com a implementação do limitador supercondutor em uma turbina eólica de 2MW. São avaliados aspectos tais como limitação de corrente, influência na resposta e atendimento à normativa de suportabilidade para duas posições do limitador dentro do elo-CC do conversor back-to-back. Os resultados obtidos demonstram que a inserção do limitador no elo-CC limita a corrente no rotor durante a ocorrência de afundamentos de tensão, ao mesmo tempo em que mantém a tensão do elo-CC em valores seguros, confirmando a validade da proposta. / In a context of necessity to increase electric energy offer and to search clean and renewable energy sources, wind energy have experienced an expressive expansion through the last few years. One of the most employed wind generators, the DFIG, has its performance significantly affected by grid disturbances, especially voltage sag. Topology and control solutions have been presented to increase generator’s supportability to these phenomena. This work verifies the use of superconducting resistive current limiter placed on back-to-back converter DC-link to protect the converter and to increase low voltage ride-through for a DFIG-based wind generator. The application of superconducting technology on wind systems protection is novel and the obtained results contribute with other works in this area. Under DFIG normal operation, the superconductor doesn’t transits to conductor state and remains invisible to the system. During a voltage dip the rotor circuit current surpasses the device critical current turning the superconductor to a conductor state inserting a resistive element, limiting the hazardous current. The studies are made through electromagnetic transient simulation software PSCAD/EMTDC with implementation of a superconducting current limiter on a 2MW wind turbine. Aspects as current limitation, response influence and supportability standard attendance are evaluated for limiter inside back-to-back converter DC-link in two different settings. The obtained results demonstrate that if voltage sag occurs the limiter insertion on DC-link limits the rotor current at the same time that it maintains DC-link voltage in safe values, proving the proposal validly.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-09-28T20:11:27Z No. of bitstreams: 1 FilipeEmanuelVieiraTaveiros_DISSERT.pdf: 11147293 bytes, checksum: e0376f15955899a774d145970625a91c (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2015-10-01T13:41:25Z (GMT) No. of bitstreams: 1 FilipeEmanuelVieiraTaveiros_DISSERT.pdf: 11147293 bytes, checksum: e0376f15955899a774d145970625a91c (MD5) / Made available in DSpace on 2015-10-01T13:41:25Z (GMT). No. of bitstreams: 1 FilipeEmanuelVieiraTaveiros_DISSERT.pdf: 11147293 bytes, checksum: e0376f15955899a774d145970625a91c (MD5) Previous issue date: 2014-05-28 / A humanidade encontra-se numa ?poca de desenvolvimento tecnol?gico sem precedentes.A ci?ncia alcan?ou e continua alcan?ando conquistas que permitem compreender cada vez mais o universo e as leis que o regem e, tamb?m, tentar coexistir sem destruir o planeta em que vivemos. Um dos principais desafios do s?culo XXI ? buscar e incrementar a gama de fontes de energias limpas, renov?veis e capazes de sustentar nosso crescimento e estilo de vida. ? dever de cada pesquisador dedicar-se e contribuir nesta corrida energ?tica. Neste contexto, a energia e?lica se apresenta como uma das grandes promessas para o futuro da gera??o el?trica. Apesar de ser um pouco mais antiga que outras fontes de energia renov?vel, a gera??o e?lica ainda apresenta um vasto campo para melhoramento. O desenvolvimento de novas t?cnicas de controle do gerador juntamente com o desenvolvimento de laborat?rios de pesquisa especializados em gera??o e?lica formam um dos pontos chave para aumentar o rendimento, a efici?ncia e a confiabilidade do sistema. O controle apropriado do esquema de conversores back-to-back permite que as turbinas e?licas baseadas no gerador de indu??o duplamente alimentado (DFIG) operem no modo de velocidade vari?vel, cujos benef?cios incluem m?xima extra??o de pot?ncia, inje??o de pot?ncia reativa e redu??o de estresse mec?nico. O conversor do lado do rotor fornece controle de pot?ncia ativa e reativa injetada na rede, enquanto que o conversor do lado da rede fornece o controle da tens?o no link CC e fluxo de pot?ncia bi-direcional. A estrutura de controle convencional utiliza controladores PI com compensa??o feed-forward dos termos de acoplamento cruzado. Como desvantagens, esta t?cnica de controle apresenta sensibilidade a incertezas do modelo e, tamb?m, a compensa??o de termos din?micos acoplados resulta em uma estrat?gia de controle concorrente. Por isso, para superar estes problemas e eliminar os termos de acoplamento cruzado, ? utilizado uma estrutura de controle robusta com realimenta??o de estados baseada no princ?pio do modelo interno,visando melhorar o acionamento do gerador bem como o seu comportamento din?mico durante varia??es abruptas na velocidade do vento. O desempenho da t?cnica de controle proposta para o controle do gerador DFIG ser? comparado ao da abordagem de controle convencional sob condi??es de vento est?veis e rajadas. Um emulador de turbina e?lica foi desenvolvido para recriar em laborat?rio uma condi??o realista e submeter o gerador a v?rias condi??es de velocidade do vento. / The humanity reached a time of unprecedented technological development. Science has achieved and continues to achieve technologies that allowed increasingly to understand the universe and the laws which govern it, and also try to coexist without destroying the planet we live on. One of the main challenges of the XXI century is to seek and increase new sources of clean energy, renewable and able to sustain our growth and lifestyle. It is the duty of every researcher engage and contribute in this race of energy. In this context, wind power presents itself as one of the great promises for the future of electricity generation . Despite being a bit older than other sources of renewable energy, wind power still presents a wide field for improvement. The development of new techniques for control of the generator along with the development of research laboratories specializing in wind generation are one of the key points to improve the performance, efficiency and reliability of the system. Appropriate control of back-to-back converter scheme allows wind turbines based on the doubly-fed induction generator to operate in the variable-speed mode, whose benefits include maximum power extraction, reactive power injection and mechanical stress reduction. The generator-side converter provides control of active and reactive power injected into the grid, whereas the grid-side converter provides control of the DC link voltage and bi-directional power flow. The conventional control structure uses PI controllers with feed-forward compensation of cross-coupling dq terms. This control technique is sensitive to model uncertainties and the compensation of dynamic dq terms results on a competing control strategy. Therefore, to overcome these problems, it is proposed in this thesis a robust internal model based state-feedback control structure in order to eliminate the cross-coupling terms and thereby improve the generator drive as well as its dynamic behavior during sudden changes in wind speed. It is compared the conventional control approach with the proposed control technique for DFIG wind turbine control under both steady and gust wind conditions. Moreover, it is also proposed in this thesis an wind turbine emulator, which was developed to recreate in laboratory a realistic condition and to submit the generator to several wind speed conditions.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / O constante aumento da demanda energÃtica de um paÃs à sempre alvo de preocupaÃÃo para os operadores de sistemas. Isto implica diretamente no aumento do grau de exigÃncia dos novos procedimentos de rede. Dentre outros tipos de exigÃncia, o ONS (Operador Nacional do Sistema ElÃtrico), solicita, por exemplo que a tensÃo contratada seja controlada pelo solicitante em nÃveis entre 0,95 e 1,05 p.u. (230kV). Quando existem no sistema, centrais eÃlicas de geraÃÃo baseados em mÃquina de induÃÃo duplamente alimentada, esta preocupaÃÃo à ainda maior. Isto porque este tipo de mÃquina, possui seu estator conectado diretamente à rede, tendo, por sua vez, maior sensibilidade a oscilaÃÃes de tensÃo. Sabendo disto, nos Ãltimos anos a eletrÃnica de potÃncia tem estado cada vez mais presente no setor elÃtrico, a exemplo do Static Synchronous Compensator, o STATCOM, que atravÃs do gerenciamento da potÃncia reativa, pode melhorar e muito a ponto de atà anular efeitos causados por oscilaÃÃo de tensÃo. Visando uma aplicaÃÃo semelhante a esta, este trabalho investiga a operaÃÃo conjunta entre o STATCOM e centrais eÃlicas no que diz respeito ao suporte à tensÃo do sistema no qual esta incorporaÃÃo à conectada. Decidiu-se basear o estudo num cenÃrio existente no nordeste brasileiro pois desta forma, à possÃvel ter noÃÃo dos reais efeitos que um STATCOM pode trazer, positivamente, ao sistema. Este trabalho apresenta uma tÃcnica para dimensionamento do STATCOM bem como discussÃes gerais sobre possÃveis desvantagens desta aplicaÃÃo. AlÃm disso, à utilizado dois softwares para elaboraÃÃo dos resultados: MatLab, que atravÃs de scripts calcula todos pontos de interesse para a anÃlise; e ANAREDE, para verificaÃÃo e comparaÃÃo dos resultados obtidos atravÃs do primeiro software. E ainda, este estudo mostra que o script desenvolvido à capaz de designar resultados que se aproximam bastante das respostas do ANAREDE, que sÃo conferidos atravÃs do comportamento do erro das respostas de ambos os programas. Por fim, com objetivo de mostrar o funcionamento dos modos de operaÃÃo do STATCOM conectado ao sistema, sÃo explicitados resultados retirados pelo software PSCAD para um cenÃrio diferente do estudado. / The constant increase in energy demand of a country is always the target of concern for system operators. This implies directly in increasing degree of requirement of the new grid procedures. Among other types of requirement, the ONS (National Electricity System Operator), requests, for example that the tension is controlled by contractor requestor is always controlled between 0.95 and 1.05 p.u.. When there are in the system, wind generation plants based on doubly fed induction machine, this concern is even greater. This is because this type of machine, has its stator connected directly to the network, and in turn more sensitive to voltage fluctuations. Knowing this, in recent years the power electronics is being increasingly present in the electricity sector to mitigate these failures, the example of Static Synchronous Compensator, the STATCOM, that through the management of reactive power, can improve and the point until oscillation effects of annular tension. Targeting an application similar to this, this work brings an idea of STATCOM operating in conjunction with wind farms on serviceability of the desired bar voltage. It was decided to base the study on existing scenario in northeastern Brazil because this way, you can get a sense of the real effects of a STATCOM can bring, positively, to the system. This paper presents a technique for STATCOM sizing as well as general discussions about possible disadvantages of this application. In addition, is used two softwares for preparation of results: MatLab, which through scripts calculates all points of interest for analysis; and ANAREDE, for verification and comparison of the results obtained through the first software .

The objective of this dissertation is to carry out dynamic modeling, analysis and control of power systems with Renewable Energy Sources (RES) such as: Photovoltaic (PV) power sources and wind farms. The dissertation work is mainly focused on microgrid since it plays a major role in modern power systems and tend to have higher renewable power penetration. Two main theoretical concepts, dynamic phasor and impedance modeling have been adopted to model and analyze the power systems/mocrogrids with RES. The initial state calculation which is essential for small signal analysis of a system is carried out as the first step of the dissertation work. Dynamic phasor and impedance modeling techniques have been utilized to model and analyze power systems/micogrids as the second phase of the work. This part consists of two main studies. First case investigates the impedance modeling of Thyristor Controller Series Capacitor (TCSC) for sub-synchronous resonance (SSR) analysis where a wind farm is connected to a power system through series compensated line. Second case utilizes the dynamic phasor concept to model a microgrid in unbalanced condition. Here the unbalance is caused by a single phase PV connected to the microgrid. Third Phase of the dissertation work includes upper level control of the microgrid. Here prediction and optimization control for a microgrid with a wind farm, a PV system, an energy storage system and loads is evaluated. The last part of the dissertation work focuses on real time modeling and hardware in loop simulation test bed for microgrid applications. This dissertation has led to four journal papers (three accepted, one submitted) and five conference papers.

This paper presents renewable energy, power electronics, and distributed generators. The focus is on wind farm generator, photovoltaic cell, and battery bank system. Power Conditioning system improves the performance of a power system. Apart from the benefits of converting between DC/AC, there is adequate control of real power and additional control of economic reactive power. This is possible because of multiple sources in the system. This project throws light on the basic principle of power system conditioning, its operation and control, and the economic studies.