This thesis is to investigate the voltage sag, transient stability and operation feasibility of power islanding with different types of dispersed generation in distribution systems. One radial distribution feeder of Taiwan Power Company (TPC) is selected for computer simulation. The mathematical models of dispersed generations including exciters, governors of steam turbine and frequency controller of wind-driven induction generator are used in the simulation program of Matlab/Simulink. Applying the dispersed generation system with synchronous and induction generators at different locations of the test feeder by executing the short circuit and motor starting analysis to find the discrepancy in the voltage sag and the relation between the motor voltage with the motor power. Finally the simulation analysis of transient stability is executed for unbalance distribution systems with dispersed generations of steam turbines and wind-driven turbines by considering two different operation scenarios after the distribution system has been disconnected from TPC system. Different load and output power control of dispersed generation are applied to maintain the stable operation of the islanding power system. Based on the transient stability analysis, it is suggested that the service reliability of power system with critical loads can be enhanced by the dispersed power generation with proper design of load shedding and output power control.

The purpose of thesis is to investigate the transient stability and operation feasibility of power islanding with different type of dispersed generation in distribution system. A substation of Taipower system is selected for case study to simulate the system transient stability. The mathematical models of dispersed generations including exciters, governors of gas turbine and pitch controller of wind-driven induction generator are used in the simulation program. To represent the load behavior more accurately, the load ratio of residence, commercial, industrial customer class and the composition of electric equipments in feeder, such as induction motors, air conditioners etc, have been identified through load survey study. The load models of end users are employed in simulation to solve the power consumption as function of bus voltage and system frequency. Besides, the dynamic model of induction motors is integrated to solve more accurate system power demand under transient condition. The simulation analysis of transient stability is executed for unbalance distribution system with dispersed generations of gas turbines and wind-driven turbines with three operations sceneries after the distribution system has been disconnected from Taipower system. Different load shedding schemes and output power control of dispersed generation are considered to maintain the stable operation of islanding power system. It is suggested that the system reliability of power system can be enhanced by the dispersed power generation with proper design of load shedding in the transient stability analysis.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-09-21T17:33:46Z No. of bitstreams: 1 viniciussobreiralacerda.pdf: 3531215 bytes, checksum: 422eca8f67f53625eceb5e46317386f9 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-09-26T20:27:18Z (GMT) No. of bitstreams: 1 viniciussobreiralacerda.pdf: 3531215 bytes, checksum: 422eca8f67f53625eceb5e46317386f9 (MD5) / Made available in DSpace on 2016-09-26T20:27:18Z (GMT). No. of bitstreams: 1 viniciussobreiralacerda.pdf: 3531215 bytes, checksum: 422eca8f67f53625eceb5e46317386f9 (MD5) Previous issue date: 2010-08-30 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Este trabalho aborda a análise, a modelagem matemática, o projeto e a simulação computacional de um sistema monofásico de aproveitamento fotovoltaico (PV) nãoisolado conectado à rede elétrica, em que se pretende sintetizar uma corrente de baixa distorção harmônica mantendo-se o ponto de máxima potência dos painéis. São avaliadas duas estruturas conversoras equivalentes, uma com dois estágios de processamento de energia e outra com apenas um estágio. Ambas as estruturas desempenham o papel de converter a energia CC dos painéis fotovoltaicos em energia CA, sob a forma de corrente elétrica de baixa distorção injetada na rede. Uma revisão sucinta dos modelos matemáticos de representação do comportamento termo-fotoelétrico do painel fotovoltaico (ou conjunto de painéis) é realizada, resultando na adaptação de uma das alternativas na forma de modelo numérico adaptado à ferramenta computacional PSIM. Algumas alternativas monofásicas de conversão CC-CA são elencadas neste trabalho, com destaque para o número de estágios de conversores, característica de isolamento e qualidade da energia injetada. Como base nesta análise, propõe-se um sistema composto por um conversor CCCC tipo buck operando em modo de condução contínua em alta frequência, em cascata com um inversor fonte de corrente (CSI) acionado na frequência da rede, para realização do aproveitamento fotovoltaico desejado. Amparado por ferramentas de integração de estágios de conversores, percebe-se que o conjunto de dois estágios pode ser arranjado em uma única etapa conversora baseada no inversor fonte de tensão (VSI). Ambas as propostas são modeladas, projetadas e simuladas no PSIM. A descrição teórico-matemática da planta PV, incluindo suas malhas de controle, é realizada. Com propósito de validação das concepções teóricas, tais sistemas são simulados, inicialmente, empregando-se elementos idealizadores e, em segundo momento, adotando-se um arranjo que inclui alguns componentes parasitas, sensores em escala real e o subcircuito do integrado UC3854. Os resultados numéricos, realizados para variações da irradiação solar e perturbações na tensão da rede, confirmam que o conceito proposto é factível, resultando em uma alternativa simples, compacta e possivelmente de baixo custo. / This work deals with the analysis, mathematical modeling, design and computer simulation of a single phase non-isolated photovoltaic (PV) system, which is connected to the electrical grid and is controlled to synthesize a low harmonic current while keeps the maximum power point of the panels. Two structures are evaluated, one with two stages of processing power and another with a single stage. Both structures converts DC power from solar panels into AC power, in the form of a low distortion electrical current to be injected into the grid. A brief review of PV panel mathematical models is performed, resulting in the adaptation of one alternative in the form of a numerical model oriented to the computational tool PSIM. Moreover, some alternatives to single-phase DC-AC conversion are listed in this work, highlighting the number of stages of inverters, isolation characteristic and quality of the power injected. To support this analysis, a two-stage system has been firstly studied, which is constituted of a buck converter operating in continuous conduction mode at high frequency, cascaded with a current source inverter (CSI) which works in the frequency of the grid. Using the integration of stages theory, the two stage system can be arranged into a single stage converter based on a voltage source inverter (VSI). Both proposals are modeled, designed and simulated in PSIM program. The theoretical and mathematical description of the PV plant, including its control loops, is presented. With the purpose of validation of the theoretical concepts, such systems are simulated, initially, using idealized elements, and then, adopting an arrangement that includes some parasitic components, sensors and full-scale integrated subcircuit of UC3854. The numerical results carried out for changes in solar radiation and mains voltage sags/swells, confirm that the proposed concept is feasible, resulting in a simple, compact and potentially low cost.

Le développement de la production éolienne permet de satisfaire les objectifs de lutte contre le réchauffement climatique. Cependant, dans certaines zones du réseau électrique, l’intégration d’un volume important de production peut créer des congestions qui traduisent l'incapacité du réseau à évacuer cette production. Les méthodes actuelles pour gérer les congestions sont basées sur des calculs prévisionnels de restrictions de production qui peuvent entrainer des pertes de production importantes pour le renouvelable. Cependant, dans le cadre d’un développement important du renouvelable, il est nécessaire de définir une méthodologie de gestion des congestions fiable, optimale du point de vue économique et non discriminatoire pour la production renouvelable.Dans le cadre de cette thèse, la méthodologie de gestion des congestions locales proposée repose sur l’usage d’un contrôle correctif. Le contrôle correctif est basé sur une boucle de régulation et un algorithme utilisant les réseaux de Petri. Une étude de stabilité de la boucle de régulation a montré que les marges de stabilité dépendantes des gains composant la boucle sont suffisantes. L’algorithme permet de définir les groupes de production à choisir pour la gestion des congestions en considérant leur coût d’utilisation et leur impact sur la congestion. Les essais, effectués sous le logiciel EUROSTAG, ont montré la pertinence de la méthodologie proposée et sa capacité à s’adapter à l’insertion des moyens de production. De plus, des conclusions générales sur les différents coûts associés à la gestion des congestions en fonction des différentes règlementations régissant la production renouvelable ont été obtenues / Development of wind generation is a mean towards global warming reduction. However, in some parts of the electrical grid, the massive integration of renewable generation can lead to congestion problems. These congestions are related to the impossibility for the power grid to transport the generation. Nowadays, congestion management methods are based on day(s)-ahead computation of generation restriction which leads to important production losses for renewables. Based on this context, it’s therefore important to develop a methodology which is optimal, reliable and non-discriminatory for renewable.In this work, the proposed congestion management method is based on corrective actions. These actions are computed in real-time using regulation loops and Petri net-based algorithms. A stability study proved that gain margins are sufficient to assure the stability of the corrective actions. The algorithm allows an optimal selection of the generators than will participate in the congestion management. This selection is based on their cost and efficiency for congestion alleviation. Simulation results using the software EUROSTAG have shown the efficiency of the method and its adaptability to different generator types. Furthermore, general conclusions on congestions costs according to different regulations on the renewable generation were obtained

Dans le domaine des réseaux de distribution d'électricité, l'ouverture du marché de l'énergie à la concurrence et l'insertion massive des génératrices décentralisées d'énergie de ces dernières années conduisent à une profonde modification du fonctionnement et de l'exploitation des réseaux. Dans ce contexte, des solutions de pilotage de la consommation et de la production doivent être apportées, afin de permettre au réseau actuel d'accueillir les nouvelles unités de production et les charges de demain, telles que les panneaux photovoltaïques, les micro-éoliennes, la cogénération, les véhicules électriques, les maisons intelligentes, etc. Ces pilotages permettent d'influencer la consommation et la production instantanées des utilisateurs du réseau. Ainsi, il devient possible d'agir sur la consommation de façon à lisser les pics ou synchroniser la demande aux périodes de forte production des énergies renouvelables. De la même façon, la production peut être pilotée pour participer aux services systèmes. Ces stratégies de pilotage, basées sur l'utilisation des nouvelles technologies de l'information et de la communication, ont pour objectifs d'éviter une dégradation de la qualité de l'onde de tension et une reconstruction complète du réseau de distribution, qui serait économiquement très couteuse. Ces travaux, intégrés au projet GreenLys, financé par l'agence française de l'environnement et de la maitrise de l'énergie, évaluent l'impact des génératrices décentralisées d'énergie et des véhicules électriques sur le réseau de distribution, puis développent des solutions de pilotage. Deux types de pilotage sont étudiés : le pilotage de la phase de raccordement d'une installation monophasée, puis le pilotage de la puissance réactive des génératrices décentralisées d'énergie. Ces pilotages sont développés en s'appuyant sur les nouveaux composants des réseaux électriques de demain, comme les compteurs intelligents. Dans une dernière partie, les stratégies de pilotage développées sont évaluées sur des équipements réels à partir d'une plateforme de simulation hybride temps réel. / In the electricity distribution network field, because of the electricity market opening and the large-scale insertion of dispersed generators (DJ) in these last years, the network undergoes radical modification in both operation and exploitation. In this context, some new integration solutions are invented in order to be able to connect the DJ, as photo-voltaic panels, micro wind turbines, cogeneration units, etc, and the new loads, as electric vehicles and smart home, without reduce the voltage wave quality or involve a very expensive power systems reinforcement. The objectives of those solutions are to influence the consumer consumption in order to reduce the peak consumption level and shift the consumption on the high renewable production period, and control the DJ output to participate to the service system. The new information and communication technologies (NICT) are strongly used in the development of those control strategies. This PhD work is including in the French project GreenLys supported by the French environment and energy management agency. GreenLys is a 4 years project focus on the development of a real scale Smart Grid in the two French cities Lyon and Grenoble. As a first step, this work evaluating the impact of the DJ and the electric vehicle on the distribution network. From the result of this impact study, two types of decentralized control strategies are investigated. The first one is focus on the phase connection. Since the majority of consumers and DJ connected on the distribution grid are single phases, methods allowing to choose the best phase connection are study. The second one is focus on new DJ reactive power control strategies. In the last part, the strategies are evaluated on a Power Hardware In the Loop simulation and real solar inverter.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-19T19:08:59Z No. of bitstreams: 1 filipecaixeiromattos.pdf: 2641141 bytes, checksum: 014bbdead0d71ad1d9852cb7403b3439 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-20T12:46:42Z (GMT) No. of bitstreams: 1 filipecaixeiromattos.pdf: 2641141 bytes, checksum: 014bbdead0d71ad1d9852cb7403b3439 (MD5) / Made available in DSpace on 2017-04-20T12:46:42Z (GMT). No. of bitstreams: 1 filipecaixeiromattos.pdf: 2641141 bytes, checksum: 014bbdead0d71ad1d9852cb7403b3439 (MD5) Previous issue date: 2011-09-02 / Esta dissertação apresenta uma contribuição ao estudo de um inversor de tensão monofásico (VSI – Voltage Source Inverter), com saída em corrente, aplicado ao processamento de energia em sistemas solares fotovoltaicos (PV) monofásicos conectados à rede elétrica de distribuição. Através do controle por corrente média, é possível em um único estágio de processamento de energia rastrear o ponto de máxima potência do arranjo fotovoltaico e injetar na rede elétrica uma corrente com baixa distorção harmônica total (THD) e em fase com a tensão da rede CA. Para implementação do controle do sistema é utilizado o circuito integrado UC3854, da Texas Instruments, componente analógico de baixo custo e com funções típicas de correção de fator de potência de fontes de alimentação. Equações de análise e projeto, resultados de simulação e informações experimentais, obtidas de um protótipo de 720W, são incluídos neste material. / This dissertation presents a contribution to the study of a single-phase voltage inverter (VSI – Voltage Source Inverter), with current output, applied to the processing of photovoltaic (PV) solar power connected to single-phase electric distribution network. By controlling the average current, it is possible, in a single stage of power processing, to track the maximum power point of PV array and inject into the grid a current with low total harmonic distortion (THD) and in phase with the AC mains voltage. To implement the control system it is used a low cost Texas Instruments' analog integrated circuit UC3854, which includes a power factor correction typical function. Equations concerning analysis and design steps, simulation results and experimental data obtained from a 720W prototype are included in this document.

Le Système Électrique est soumis ces dernières années à plusieurs évolutions, depuis la dérégulationdu marché d'énergie à l'intégration de plus en plus importante de Générateurs Dispersés (GED). Ainsi,dans le cadre du concept de Smart Grid, les nouvelles technologies de l'information et de lacommunication (NTIC) offrent de nouvelles perspectives pour la gestion et l'exploitation des réseauxde distribution.Dans ce contexte, de nouveaux outils sont étudiés. Encore appelés Fonctions Avancéesd’Automatisation (FAA), le but principal de ces outils est d’utiliser tous les composants du réseau dedistribution de manière coordonnée en vue de les rendre plus actifs, flexibles et d’augmenter leurefficacité opérationnelle. Dans notre cas, nous avons étudié les fonctions associées à la reconfigurationen régime normal, du réglage de la tension et l’hybridation de ces deux derniers, tout en tenant comptede la présence des GED. En partant du comportement physique inhérent aux composants du réseau,plusieurs modèles ont été proposés. Certains sont tirés de la théorie des graphes et d’autres sur l’outilpuissant de la reformulation mathématique pour « convexifier » nos modèles. Cette modélisationadoptée répond à la fois à la nécessité de prendre en compte tous les moyens de réglages qui peuventêtre discrets (prises des transformateurs avec régleurs en charge ou des gradins de condensateurs),binaires (état de connectivité des composants) et continues (puissance réactive de la DG) et par lechoix des outils et des algorithmes d'optimisation mixte. En effet, la complexité de ces problèmes sonttelles que nous avons exploré à la fois des algorithmes méta-heuristiques (ACF : Algorithme desColonies de Fourmis) que déterministes (Décomposition de Benders Généralisée, Algorithme duBranch and Cut). / The Electric Power System is undergoing a lot of evolutions in recent years, including the energymarket deregulation and the increasing integration of Dispersed Generators (DG). Therefore, withinthe framework of Smart Grid concept, the New Information and Communication Technologies (NICT)provide new perspectives to manage and operate distribution networks.In this context, new tools, called Advanced Distribution Automation functions (ADA, are beingstudied). The main objective of these tools is to use all the distribution network components in acoordinated manner to make them more active and flexible, in addition to increasing their operationalefficiency. In our case, we studied the functions associated with the reconfiguration problem, thevoltage control problem and the hybridization of these two, while taking into account the presence ofthe DG. Based on the inherent components of network physical models, several models have beenproposed. Some are derived from the graph theory and others use powerful mathematicalreformulation to make our models convex. The adopted models answer to the necessity of taking intoaccount all regulation means, which can be discrete (On Load Tap-Changer and capacitor banks),binary (components connectivity such as lines or transformers) and continuous (DG reactive power ),and by the choice of tools and algorithms of mixed optimization. Indeed, the complexity of theseproblems is such that we have explored both algorithms: meta-heuristic (ACA, Ant Colony Algorithm)and deterministic (Generalized Benders Decomposition, Branch and Cut Algorithm).

This study concerns frequency relays and voltage relays applied to the protection of synchronous distributed generators operating in reactive power control mode without a frequency regulation function. The effect of active and reactive powers combination, load power factor, and reactive power imbalance are investigated for their implication for the anti-islanding setting of the frequency relay. Results reveal that the effect of these factors must be considered when setting the relay for islanding detection. For the voltage relay, results reveal that the effect of active and reactive powers combination, load power factor, and active power imbalance must be considered when setting the relay for islanding detection. The effect of multi-stage tripping on the frequency relay ability to detect island was also investigated. Results show that multistage tripping can improve the anti-islanding performance of the frequency relay. / Electrical Engineering / M. Tech. (Electrical Engineering)

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-26T12:14:24Z No. of bitstreams: 1 gabrielazevedofogli.pdf: 13619054 bytes, checksum: d260cb2571f242e43eab89132a03d62c (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-26T12:26:45Z (GMT) No. of bitstreams: 1 gabrielazevedofogli.pdf: 13619054 bytes, checksum: d260cb2571f242e43eab89132a03d62c (MD5) / Made available in DSpace on 2017-04-26T12:26:45Z (GMT). No. of bitstreams: 1 gabrielazevedofogli.pdf: 13619054 bytes, checksum: d260cb2571f242e43eab89132a03d62c (MD5) Previous issue date: 2014-03-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Esta dissertação apresenta um estudo de conexão de um grupo gerador-diesel (GMG) trifásico em uma rede secundária de distribuição de energia elétrica. A integração do GMG é feita por uma unidade de processamento de energia (PPU) composta por um retificador trifásico não controlado conectado em série com um conversor fonte de tensão (VSC) modulado com uma estratégia de modulação por largura de pulso. O GMG pode operar de duas maneiras distintas: (i) modo standby (interligado) ou (ii) modo isolado. O conversor de saída da PPU pode ser controlado para injetar potência ativa na rede CA, ou como um filtro ativo de potência (FAP) compensando potência reativa e correntes harmônicas nos terminais das cargas. O VSC de interface é controlado no modo de corrente (CMC), sendo seus controladores projetados a partir de funções de transferência obtidas com o modelo matemático do sistema elétrico nas coordenadas dq0. Esses controladores são projetados com múltiplos integradores para garantir a qualidade da forma de onda da corrente injetada na rede CA. Dependendo do modo de operação é utilizada uma malha adicional para regular a tensão do barramento CC do conversor de interface. Para validar o modelo matemático e o algoritmo de controle são realizadas simulações digitais no programa PSIM. Resultados experimentais, obtidos com um protótipo de laboratório, cujos controladores foram implementados em um processador digital de sinais TMS320F28335 da Texas Instruments, são usados para validar as estratégias de controle propostas. / This dissertation presents a study about the connection of a three-phase Diesel Genset (DG) to a secondary distribution network. The integration of DG is done by a Power Processing Unit (PPU) composed of a three-phase rectifier connected in series with a Pulse Width Modulated Voltage Source Converter (VSC). The DG can operate in two distinct modes: (i) standby (interconnected) or (ii) islanding. The PPU’s output converter can be controlled to inject active power into AC electric grid, or as an Active Power Filter (APF), compensating the reactive power and harmonics currents at the load terminals. The VSC is controlled employing the current mode control (CMC), and its compensators are designed based on the electrical system transfer function in dq0 coordinates. Multiple rotating synchronous reference frame integrators (PI-MRI) are used to ensure the quality of the generated power. Depending on the operating mode, an additional loop is used to regulate the DC bus voltage. In order to validate the mathematical model and the control algorithm, digital simulations using PSIM are performed. Experimental results obtained with the prototype, which controllers were implemented in a TMS320F28335 of Texas Instruments are used to validate the proposed control strategies.

The diploma thesis deals with dispersed generation (production). The small electric power sources are connected into distribution networks. Types and principles of the small electric power sources are studied. The legislation framework concerning renewable energy sources utilization is described. These power plants have impact into distribution networks and therefore techniques for the source connection to distribution network are included in the thesis. The impact of the specific small source of electricity must be studied.