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Ce mémoire est consacré à l'étude du phénomène d'instabilité pouvant apparaître sur les bus continus des réseaux DC. En effet, l'interaction entre les différents sous-systèmes électriques (source, charge, filtre) composant le réseau DC peut conduire, sous certaines conditions, à l'instabilité du système. A partir de la modélisation des charges sous forme de "Charge à Puissance Constante" (notée CPL), des méthodes d'études permettant l'analyse de la stabilité "petit-signal" et "grand-signal" des systèmes électriques sont présentées. Celles-ci permettent de mettre en évidence le fait qu'un réseau DC ne peut pas fournir n'importe quelle puissance à ses charges sans devenir instable. Ces puissances limites dépendent à la fois de la structure du réseau et des valeurs de ses éléments passifs et de sa tension de bus. Afin de pouvoir augmenter l'amortissement/les marges de stabilité du système, des méthodes de stabilisation sont présentées dans ce mémoire. Elles proposent d'adapter les commandes des charges de manière à assurer sa stabilité. Ceci se fait grâce à l'addition d'un signal stabilisant sur la référence de chaque charge. Ce signal n'est visible que durant les régimes transitoires de la charge afin de ne pas modifier le point de fonctionnement demandé. Néanmoins, plus on voudra stabiliser une charge et plus son signal stabilisant sera important. Un bon compromis doit donc être trouvé afin d'assurer la stabilité du système sans altérer les performances dynamiques des charges. Deux approches différentes sont proposées afin de générer ces commandes stabilisantes. La première se base sur la mise en place d'un stabilisateur centralisé. Deux méthodes centralisées sont alors proposées : la première s'appuie sur la théorie des multimodèles de Takagi-Sugeno alors que la seconde s'appuie sur la théorie de Lyapunov. Cette dernière permettra d'orienter les efforts de stabilisation sur les charges souhaitées pour par exemple, les diriger principalement vers les organes de récupération d'énergie. La seconde approche se base sur la mise en place d'un système de stabilisation multi-agent. Celui-ci présente une structure décentralisée où chaque agent correspond à un bloc de stabilisation. Ceux-ci vont compenser localement les impacts déstabilisants de leur charge respective et leurs actions combinées permettront d'assurer la stabilité du système. De plus, on propose d'utiliser un algorithme d'optimisation sous contraintes qui permettra de donner un dimensionnement du système minimisant les efforts de stabilisation tout en considérant des cas de défaut tels que la perte de l'un des agents ou la reconfiguration du réseau / This thesis is devoted to the analysis of the instability phenomenon that may appear on the DC bus of DC microgrids. Indeed, interaction between the different electrical subsystems of the grid (source, load, filters) can lead, under certain conditions, to the system instability. From the "Constant Power Load" (CPL) hypothesis for the loads, this thesis presents studying methods for "small-signal" and "large-signal" stability analysis of electrical systems. This highlights that a DC microgrid cannot power the loads more than a maximum limit without becoming unstable. This power limitation depends on the structure of the grid, the value of its passive components, and its bus voltage. In order to improve the microgrid stability, stabilization methods are presented in this thesis. They propose to adapt the loads control to ensure the system stability. This is achieved by the addition of a stabilizing signal to the reference of each load. This signal is only visible during the load power transient mode to not change the requested operating point. However, a good trade-off must be found to ensure system stability without affecting the dynamic performance of its loads. Two approaches are investigated to generate the stabilizing commands. The first one is based on the establishment of a centralized stabilization block. Two centralized methods have been developed: the first one is based on the Takagi-Sugeno theory while the second is based on the Lyapunov theory. This latest permits to guide the stabilizing effort on the desired loads. For example, stabilizing effort can be oriented on the energy storage device. The second approach is based on the establishment of a multi-agent stabilizing system. It consists of a decentralized structure in which each agent corresponds to a stabilization block. These will locally compensate the destabilizing impact of their respective load on the microgrid, and their combined actions ensure the system stability. To design the system, the use of a constrained optimization algorithm is proposed. This permits to minimize stabilization efforts while considering faulty events such as the failure of one of the agents or a reconfiguration of the microgrid

Orientador: Percival Bueno de Araujo / Resumo: As perturbações ou variações de carga produzem oscilações eletromecânicas que devem ser amortecidas o mais rápido possível para garantir confiabilidade e estabilidade da rede. Neste trabalho apresenta-se uma análise do dispositivo FACTS Interline Power Flow Controller (IPFC) e o controlador Proporcional Integral (PI) no gerenciamento dos fluxos de potência e a influência dos Estabilizadores do Sistema de Potência (ESP) e do IPFC Power Oscillation Damping (POD) sobre a estabilidade do sistema elétrico de potência. Neste trabalho enfoca-se nos estudos de estabilidade a pequenas perturbações usando um Algoritmo Genético Adaptativo com Hiper-mutação (AGAH) para ajustar os parâmetros dos controladores suplementares de amortecimento, o Estabilizador de sistema de potência (ESPs) e o Power Oscillation Damping (POD) em forma coordenada. O AGAH tem como objetivo encontrar os parâmetros ótimos do controlador para melhorar o amortecimento fraco das oscilações de baixa frequência locais e inter-área. Neste trabalho representa-se o sistema de elétrico de potência com a inclusão do dispositivo Interline Power Flow Controller com o modelo de sensibilidade de corrente (MSC). Considera-se como sistema teste o sistema Simétrico de Duas Áreas e o sistema New England como o intuito de avaliar o algoritmo proposto. As simulações são feitas no ambiente do MatLab. Por fim, apresenta-se a comparação do algoritmo genético com o desempenho do algoritmo proposto. / Abstract: Small-magnitude disturbances happen to produce electro-mechanical oscillations which should be damped as quickly as possible to ensure reliability and stability of the network. This work presents an analysis of Interline Power Flow Controller (IPFC) FACTS device and PI controller to control and manage power flow and also how Power System Stabilizers and IPFC Power Oscillations Damping (POD) controller influence over an electric power system stability. This work focuses on small-signal stability studies using an Adaptive Genetic Algorithm with Hyper-mutation (AGAH) in order to tune controller parameters in a coordinated way ensuring proper damping. AGAH aims to find optimal controller parameters to enhance the poor damping of local and inter-area low frequency oscillations. This works represents the electric power system and Interline Power Flow Controller device by a current sensitivity model (CSM). This paper considers two areas 14 bus symmetrical power system and New England power system in order to assess proposed algorithm. Coding and Simulations take place in MatLab platform. AGAH and GA get compared by time convergence and performance. This paper shows AGAH is an interesting optimization technique which outweighs GA. / Mestre

Small signal oscillation has been always a major concern in the operation of power systems. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system. Following any disturbance, such as sudden change in loads, actuations in the output of turbine and faults etc. it exhibits an oscillatory behaviour around the equilibrium state. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of these low frequency oscillations. Small oscillations in the range of about 0.1Hz to 3.5Hz can persist for long periods, limiting the power transfer capability of the transmission lines. These oscillations can be reduced by incorporating auxiliary controllers on generator excitation system. Power System Stabilizers (PSSs) were developed to produce additional damping by modulating the generator excitation voltage. Designing effective PSS for all operating conditions especially in large interconnected power systems still remains a difficult and challenging task. More and more power electronic based controllers have been and will be used in power systems. Many of these controllers such as Static Var Compensators (SVCs), Static Synchronous Compensators (STATCOMs) and Unified Power Flow Controllers (UPFCs) etc., are incorporated in power transmission networks to improve its operational capability. In addition, some of the energy storage systems such as Battery Energy Storage systems (BESS), Super conducting Magnetic Energy Storage System (SMES) as well large non-conventional energy sources are also increasingly being integrated with the power grid. With large integration of these devices, there is a significant impact on system stability, more importantly on small signal oscillatory instability of the power system. This thesis primarily focuses on impact of such devices on small signal oscillatory stability of the power systems. More specifically in this thesis small signal stability analysis of a Single Machine Infinite Bus (SMIB) system with a grid connected wind powered Permanent Magnet Synchronous Generator (PMSG) has been presented. A SMIB system has been purposely chosen so that general conclusions can be obtained on the behaviour of the embedded STATCOM/Energy Source (ES) system on system stability. With a better understanding of the impact of such a system it would be probably possible to analyze more complicated multimachine power system and their impact on system stability. Small signal model of the complete system which comprises the generator, transmission network, inter connecting STATCOM, the wind power generator and all associated controllers has been developed. The performances of the system following a small disturbance at various operating conditions have been analyzed. To obtain quantitative estimates of the damping and synchronizing torques generated in the system, expressions for damping and synchronizing torque clients have been developed. With these analyses, the relative impact of the STATCOM and STATCOM with ES on system performance have been assessed. It is shown that with active and reactive power modulation capabilities effective and efficient control of small signal oscillations in power systems can be achieved.

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No. of bitstreams: 1 nunesneto_o_dr_bauru.pdf: 4276326 bytes, checksum: e73a2086ffde0d12d2f5875fb168f8c1 (MD5) Previous issue date: 2016-04-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Materiais e dispositivos baseados em compostos orgânicos desempenham um importante papel em diversas áreas da aplicação tecnológica devido às suas interessantes propriedades eletro-magneto- ópticas, adicionadas às suas características mecânicas únicas, facilidade de processamento, versatilidade de síntese e baixo custo relativo. Apesar do proeminente campo de aplicação destes materiais, muitos aspectos associados à sua ciência básica são ainda pouco compreendidos. Nesse cenário destaca-se o fenômeno de Magnetoresistência Orgânica (OMAR, da sigla em inglês). Tal fenômeno encontra-se associado a variações significativas da condutividade elétrica de dispositivos orgânicos induzidas por pequenos campos magnéticos externos em temperatura ambiente e tem sido observado em diversificados materiais poliméricos e moleculares. No presente trabalho avaliou-se o fenômeno de OMAR apresentado por um Diodo Emissor de Luz baseado na molécula de Alq3. Medidas de Espectroscopia de Impedância Elétrica na presença de um Campo Magnético estático externo (EIE-CM) foram realizadas sobre o referido dispositivo para diferentes temperaturas. Métodos diferenciados de aquisição e manipulação de dados foram empregados a fim de remover a dependência temporal dos sinais tipicamente observados. Os seguintes Efeitos de Campo Magnético (MFE, da sigla em inglês) foram observados sobre a resposta elétrica do dispositivo: (i) redução de cerca de 1% na resistência, efeito praticamente constante para todo o espectro de frequência e; (ii) variações significativas na capacitância, com intensificação do efeito de Capacitância Negativa em baixas frequências. Como suporte para a interpretação dos resultados experimentais foram realizadas simulações empregando-se duas abordagens: Circuitos Equivalentes e Análise de perturbações de pequenos sinais (em inglês, Small Signal Analysis ) via soluções numéricas das equações de transporte de Boltzmann numa aproximação por Drift-Diffusion empregando-se dispositivos simplificados. As análises sugerem que os MFE evidenciados podem estar associados a um aumento da mobilidade efetiva dos portadores de carga e a uma redução na taxa de recombinação bimolecular no dispositivo. Os resultados foram interpretados em termos dos modelos atualmente aceitos para o fenômeno de OMAR. Esta tese também apresenta um estudo de processos de geração e transferência de carga em corantes Cianinas, materiais promissores para aplicações em células solares com absorção no infravermelho. Técnicas de Ressonância de Spin Eletrônico induzida por Luz foram empregadas em blendas destes corantes com o polímero MEH-PPV e com o fulereno (C60) a fim de avaliar, respectivamente, o caráter aceitador e doador de elétrons das Cianinas. / Materials and devices based on organic compounds play an important role in various technological applications, mainly due to their interesting electrical-magneto-optical properties combined with their unique mechanical properties, easy processing, versatility of synthesis and relatively low cost. Despite the prominent application field of these materials many aspects associated with their basic science are still not well understood. In this context the Organic Magnetoresistance phenomenon (OMAR) deserves to be highlighted. This phenomenon is associated with significant changes in the electrical conductivity of organic devices induced by the presence of small external magnetic fields at room temperature, being observed in various polymeric and molecular materials. In this study we have investigated the OMAR phenomenon in Alq3-based OLEDs. Electrical impedance spectroscopy technique in the presence of an external static magnetic field (EIS-MF) was employed in the experiments; distinct temperatures were considered. Differentiated methods of acquisition and data manipulation were employed to remove the typically observed signal time dependence. The following magnetic field effects (MFE) were observed on the electrical response of the device: (i) a constant reduction of around 1% in the resistance over the entire frequency spectrum and; (ii) significant changes in the capacitance followed by an intensification of the negative capacitance effect at low frequencies. Simulations employing two different approaches were carried out for the interpretation of the experimental results: (i) Equivalent Circuits and (ii) Small Signal Analysis via numerical solutions of the Boltzmann transport equations by Drift-Diffusion approach. The results suggest that the observed MFE can be associated with an increase in the effective mobility of the charge carriers and a reduction in the bimolecular recombination rate in the device. The results were interpreted in terms of the currently accepted models for the OMAR phenomenon. This thesis also presents a study about generation and charge transfer processes in cyanine dyes (near infrared absorbing compounds) which are promising materials for applications in solar cells. Light induced Electron Spin Resonance (L-ESR) technique was employed to study the presence/formation of paramagnetic centers in blends of these dyes with MEH-PPV polymer and fullerene (C60) to evaluate, respectively, the electron acceptor and donor character of cyanine dyes. / FAPESP: 2011/21830-6 / CNPq: 204432/2013-8

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master Thesis presents the development of a new dynamic model for the DC-DC Zero-Voltage-Switching Phase-Shift-Modulated Full-Bridge (ZVS-PSM-FB).At first, the ZVSPSM-FB converter is analyzed and the Steady-State equations are derived. Then, using the ac equivalent circuit modeling technique, it is derived two new ZVS-PSM-FB dynamical models, based on step operation of the converter and steady-state converter equations. These two new ZVS-PSM-FB dynamical models with two dynamical models previously presented in the literature are used to perform a frequency response and a transfer-function DC-gain comparison to verify the performance of the dynamical models. Comparison results shows that our second model here derived presents a better performance among other models, keeping the desirable characteristics as simple polynomial ratio transfer-functions, excellent theoretical accuracy of transfer-functions DC-gains, transfer-functions coefficients independency of circuit parasitics components, excepting the primary leakage inductance. Even in this work, it is shown frequency response experimental results of the ZVS-PSM-FB converter, designed following telecommunications rectifiers power supplies standards. / Esta Dissertação de Mestrado apresenta o desenvolvimento de um novo modelo dinâmico para o conversor CC-CC Ponte-Completa Modulado por Deslocamento de Fase e com Comutação em Zero de Tensão (ZVS-PSM-FB). Inicialmente, o conversor ZVS-PSM-FB é analisado, onde são derivadas as equações que definem a operação em regime-permanente do conversor. A seguir, utilizando-se da técnica de modelagem ca média de conversores estáticos, deriva-se dois novos modelos dinâmicos para o conversor, tendo por base as etapas de operação do conversor e as equações de regime-permanente. Feito isso, os dois modelos aqui derivados, são comparados com outros dois modelos dinâmicos já apresentados na literatura para verificar seus desempenhos quanto à resposta em freqüência e resposta do ganho-cc das funções de transferências à variações de carga do conversor, dos modelos dinâmicos. Resultados desta comparação mostram que o segundo modelo aqui derivado é o que apresenta melhor desempenho entre os modelos comparados, mantendo características desejáveis de simples formato de função de transferência como razão de polinômios, precisão teórica excelente para resposta de ganho-cc das funções de transferências e não-dependência dos coeficientes das funções de transferências de parâmetros parasitas do circuito, a menos da indutância de dispersão do transformador. Ainda neste trabalho, são mostrados resultados experimentais da resposta em freqüência do conversor ZVS-PSM-FB, projetado com especificações de normas para retificadores chaveados de alta-freqüência para equipamentos de telecomunicações.

Les études qui seront présentées dans le cadre de cette thèse portent sur le développement et l’optimisation des techniques pour la modélisation compacte des transistors bipolaires à hétérojonction (TBH). Ce type de modélisation est à la base du développement des bibliothèques de composants qu’utilisent les concepteurs lors de la phase de simulation des circuits intégrés. Le but d’une technologie BiCMOS est de pouvoir combiner deux procédés technologiques différents sur une seule et même puce. En plus de limiter le nombre de composants externes, cela permet également une meilleure gestion de la consommation dans les différents blocs digitaux, analogiques et RF. Les applications dites rapides peuvent ainsi profiter du meilleur des composants bipolaires et des transistors CMOS. Le défi est d’autant plus critique dans le cas des applications analogiques/RF puisqu’il est nécessaire de diminuer la puissance consommée tout en maintenant des fréquences de fonctionnement des transistors très élevées. Disposer de modèles compacts précis des transistors utilisés est donc primordial lors de la conception des circuits utilisés pour les applications analogiques et mixtes. Cette précision implique une étude sur un large domaine de tensions d’utilisation et de températures de fonctionnement. De plus, en allant vers des nœuds technologiques de plus en plus avancés, des nouveaux effets physiques se manifestent et doivent être pris en compte dans les équations du modèle. Les règles d’échelle des technologies plus matures doivent ainsi être réexaminées en se basant sur la physique du dispositif. Cette thèse a pour but d’évaluer la faisabilité d’une offre de modèle compact dédiée à la technologie avancée SiGe TBH de chez ST Microelectronics. Le modèle du transistor bipolaire SiGe TBH est présenté en se basant sur le modèle compact récent HICUMversion L2.3x. Grâce aux lois d’échelle introduites et basées sur le dessin même des dimensions du transistor, une simulation précise du comportement électrique et thermique a pu être démontrée.Ceci a été rendu possible grâce à l’utilisation et à l’amélioration des routines et méthodes d’extraction des paramètres du modèle. C’est particulièrement le cas pour la détermination des éléments parasites extrinsèques (résistances et capacités) ainsi que celle du transistor intrinsèque. Finalement, les différentes étapes d’extraction et les méthodes sont présentées, et ont été vérifiées par l’extraction de bibliothèques SPICE sur le TBH NPN Haute-Vitesse de la technologie BiCMOS avancée du noeud 55nm, avec des fréquences de fonctionnement atteignant 320/370GHz de fT = fmax. / The aim of BiCMOS technology is to combine two different process technologies intoa single chip, reducing the number of external components and optimizing power consumptionfor RF, analog and digital parts in one single package. Given the respectivestrengths of HBT and CMOS devices, especially high speed applications benefit fromadvanced BiCMOS processes, that integrate two different technologies.For analog mixed-signal RF and microwave circuitry, the push towards lower powerand higher speed imposes requirements and presents challenges not faced by digitalcircuit designs. Accurate compact device models, predicting device behaviour undera variety of bias as well as ambient temperatures, are crucial for the development oflarge scale circuits and create advanced designs with first-pass success.As technology advances, these models have to cover an increasing number of physicaleffects and model equations have to be continuously re-evaluated and adapted. Likewiseprocess scaling has to be verified and reflected by scaling laws, which are closelyrelated to device physics.This thesis examines the suitability of the model formulation for applicability to production-ready SiGe HBT processes. A derivation of the most recent model formulationimplemented in HICUM version L2.3x, is followed by simulation studies, whichconfirm their agreement with electrical characteristics of high-speed devices. Thefundamental geometry scaling laws, as implemented in the custom-developed modellibrary, are described in detail with a strong link to the specific device architecture.In order to correctly determine the respective model parameters, newly developed andexisting extraction routines have been exercised with recent HBT technology generationsand benchmarked by means of numerical device simulation, where applicable.Especially the extraction of extrinsic elements such as series resistances and parasiticcapacitances were improved along with the substrate network.The extraction steps and methods required to obtain a fully scalable model library wereexercised and presented using measured data from a recent industry-leading 55nmSiGe BiCMOS process, reaching switching speeds in excess of 300GHz. Finally theextracted model card was verified for the respective technology.

State-of-the-art SiGe BiCMOS technologies leverage the maturity of deep-submicron silicon CMOS processing with bandgap-engineered SiGe HBTs in a single platform that is suitable for a wide variety of high performance and highly-integrated applications (e.g., system-on-chip (SOC), system-in-package (SiP)). Due to their bandgap-engineered base, SiGe HBTs are also naturally suited for cryogenic electronics and have the potential to replace the costly de facto technologies of choice (e.g., Gallium-Arsenide (GaAs) and Indium-Phosphide (InP)) in many cryogenic applications such as radio astronomy. This work investigates the response of mixed-signal circuits (both RF and analog circuits) when operating in extreme environments, in particular, at cryogenic temperatures and in radiation-rich environments. The ultimate goal of this work is to attempt to fill the existing gap in knowledge on the cryogenic and radiation response (both single event transients (SETs) and total ionization dose (TID)) of specific RF and analog circuit blocks (i.e., RF switches and voltage references). The design approach for different RF switch topologies and voltage references circuits are presented. Standalone Field Effect Transistors (FET) and SiGe HBTs test structures were also characterized and the results are provided to aid in the analysis and understanding of the underlying mechanisms that impact the circuits' response. Radiation mitigation strategies to counterbalance the damaging effects are investigated. A comprehensive study on the impact of cryogenic temperatures on the RF linearity of SiGe HBTs fabricated in a new 4th-generation, 90 nm SiGe BiCMOS technology is also presented.