Programa de Pós-graduação em Engenharia Elétrica e da Computação
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Navegando Programa de Pós-graduação em Engenharia Elétrica e da Computação por Por Orientador "Alves, Antônio César Baleeiro"
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Item Modelagem e análise experimental de um protótipo didático de motor stirling(Universidade Federal de Goiás, 2016-12-05) Dias, Laura Vitória Rezende; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Guimarães, Geraldo Caixeta; Marra, Enes Gonçalves; Kitatani Júnior, SigeoThis work is the development of a prototype for Stirling engine which was designed with the aim of understanding the machine mainly about the component parts, construction difficulties and type of relevant parameters for its performance. Starting from geometric and thermodynamic data from the prototype, with application of the Schmidt modeling, a digital program was developed to calculate values such as power output and efficiency. The prototype was also used to carryd out bench tests using a data acquisition system implemented in electronics platform Arduino Uno. Using Hall-effect and temperature sensors, following the steps of the algorithm proposed by Conner, it was possible to raise data as temperature and revolutions per minute (rpm) for the flywheel coupled to the prototype shaft, these variables made possible to estimate the power output and operational conditions such as the gas temperature in compression and expansion spaces, etc. The comparison between results from simulations and the bench tests demonstrated the great influence of prototype construction data (volumes, source temperature, etc.) on the output power and the performance of the equipment and also how far is the constructed device from the ideal model proposed by Schmidt. The experiments have shown that the prototype can reach a rotation speed up to 1.200 rpm at 159 degrees Celsius of external engine heat source, with output power of 100 milliwatt. The prototype resulting from this research, although small, has allowed the access to important information that can open paths to the construction of larger Stirling engines and consequently with output powers closer to practical use.Item Reconfiguração de sistemas de distribuição de energia elétrica utilizando metodologias multipartida e busca tabu(Universidade Federal de Goiás, 2017-08-25) Marinho, Romário Pereira; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; Garcés Negrete, Lina Paola; Silva, Luis Gustavo Wesz daThe purpose of this work is the solution of the distribution network problem to minimize active power losses using meta-heuristics based on multistart methodology and tabu search. The initialization of both methodologies will be done by solving a power flow for weakly meshed systems whose apparent power will be used by Prim’s algorithm as the weight, which will generate good initial radial topologies. The local searchs implemented are through brach exchanges that aim to improve the solution. The solutions are obtained by programming algorithms implemented in C++ language, which aim to minimize the losses in the distribution feeders. This dissertation is the result of efforts made in the initial stages of the CELG D’s Research and Development (R&D) project, ANEEL’s code PD-6072-0302 / 2015. Therefore, it is one of the project’s by-products entitled: " Sistema de Apoio à Decisão para Restauração de Redes de Distribuição de Energia Elétrica Considerando Curvas de Carga dos Transformadores das SubestaçõesItem Harmônicos triplos no sistema de distribuição e uma proposta de mitigação(Universidade Federal de Goiás, 2013-09-20) Nielson, Rafael; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; Silva, Luis Gustavo Wesz da; Santos, Euler Bueno dosEste trabalho tem por finalidade analisar, de forma prática, a aplicação de filtro eletromagnético para a mitigação de distorção harmônica causada pela presença de cargas não lineares, em instalações de consumidores. Primeiramente foram analisadas as fontes típicas geradoras de distorções harmônicas, seus efeitos e formas de mitigação. Em seguida foi feito o estudo da propagação harmônica no sistema de distribuição face aos tipos de conexão de um transformador de distribuição. Este estudo foi implementado através de solução computacional a partir de um exemplo de sistema típico idealizado. No capítulo subsequente foram abordados os métodos de mitigação de harmônicos triplos, através da análise de filtros eletromagnéticos em dois arranjos, com o emprego do programa ATPDraw para simulação da modelagem matemática do filtro eletromagnético em derivação, para circuitos a 4 fios, permitindo prever prováveis dificuldades na construção do filtro e análise de desempenho do mesmo. Para permitir a elaboração do projeto e a construção do filtro eletromagnético, foi construída uma bancada para recriar cargas semelhantes àquelas encontradas em instalações de consumidores conectadas a três e a quatro fios. Com o auxílio dos dados obtidos com a utilização da bancada, o filtro foi projetado e construído. Foram realizadas medições para três situações básicas, cujos resultados foram compilados e analisados do ponto de vista do conteúdo harmônico apresentado.Item Efeitos da operação do gerador de indução no comportamento do gerador síncrono operando em um sistema isolado alimentando cargas não lineares(Universidade Federal de Goiás, 2018-07-13) Oliveira, José Mário Menescal de; http://lattes.cnpq.br/2672882686688933; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; Rodrigues, Kleiber David; Salerno, Carlos Henrique; Santos, Euler Bueno dos; Nerys, José Wilson LimaThis thesis demonstrates the effects of harmonic pollution in a salient pole synchronous generator and an induction generator operating in parallel on an isolated system, supplying a non-linear load. The main contributions of this research-study consist of identifying and quantifying the oscillations that non-linear load cause on the electric variables of synchronous and induction generators, such as, the electromagnetic conjugate that presents oscillations of sixth harmonic due to the distorted currents.Item Modelagens e solução de aterramentos sujeitos a surtos de corrente: respostas nos domínios da frequência e do tempo(Universidade Federal de Goiás, 2016-03-29) Silva, Bárbara Pereira; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Visacro Filho, Silvério; Batista, Adalberto JoséIn the grounding systems analysis, the investigation of the effects caused by lightning discharge is a crucial task, since it is the main electromagnetic phenomena responsible for electricity outages which can be the cause of severe mechanical and thermal stresses on electric installations. This dissertation presents a study of transient behavior for various grounding configurations subject to impulsive currents originated from incident discharges. The model is named hybrid electromagnetic model, because it is based on electromagnetic equations and it is used concepts of electrical circuit analysis. The modeling is performed in frequency domain considering the effects of electromagnetic propagation on the metal electrode and into surrounding soil. In the numerical solution of model is used the method of moments for the discretization of the electrodes and calculus of the impedances. This methodology also considers the variation of electric soil parameters when frequency varies. The modeling comprised the effects of propagation and electromagnetic couplings between the grounding electrodes. Results were obtained for simple electrodes (wire horizontally buried in the soil or a vertical rod) and grounding grid in square format from the computational implementation of the mathematical model. This tool and the results obtained lend itself to the determination of the grounding systems response subjected to an injection of a typical current of lightning discharge. The validation of the tool which resulted from this work is made by comparing the obtained results with results of similar cases reported in the technical literature.Item Análise da geração distribuída sob a perspectiva de maximização de potência injetada em sistemas de distribuição(Universidade Federal de Goiás, 2017-04-10) Tonhá, Henrique Mesquita; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; Silva, Luiz Carlos Pereira da; Kopcak, IgorElectricity distribution networks around the world are able to receive generators installed along their length. As the studies of the impacts of distributed generators emerge and deepen in the solution of the problems arising from the granting of installation of DGs, their benefits become more attractive than impediments not yet overcome and their dissemination becomes a irreversible tendency. One of the inconveniences faced by enterprising to the electrical system is the power limitation to be injected in the network to the situation that the enterprising one behaves like exporter, this limitation can become a factor of discouraging his input in the system. In this sense, this work searches through a well-known tool of load flow - OpenDSS to carry out tests proposing the substitution of the conductor in part of the network in order to enable more ambitious distributed generation projects from the point of view of the injected power. In addition, the impact of the voltage regulator, often found in the networks, on the maximum permissible potency to be inserted in the studied network, as well as the impact on the electric losses profile and the proposed overcurrent protection are also analyzed. The tests demonstrated that the substitution of the conductor was adequate for the maximization of power, especially when the network operates with voltage regulator. In view of the distributed generation connection and the replace the cable proposed of part of the network, the losses presented a relative reduction and the protection times were reduced due to the necessary replacement of some devicesItem Alocação otimizada de dispositivos indicadores de faltas em linhas aéreas de distribuição utilizando busca em vizinhança variável(Universidade Federal de Goiás, 2017-05-30) Vasconcelos, Jáder de Alencar; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; Morais, Flávio José de Oliveira; Brito, Leonardo da CunhaElectricity distribution networks are constantly subject to contingencies that can lead to interruption of supply, bringing disruption to consumers of electric energy and increasing the cost of compensation for violation of individual indicators of continuity. In this context, Fault Indicator Devices (PIs) have been shown to be a promising alternative to improve Quality of Service. As the use of these equipments requires considerable investments, the use of IFs in arbitrary stretches of the network is prohibitive, making necessary the development of a methodology for the optimal allocation of these devices. In this sense, it is understood that a good methodology should minimize the average time of displacement of the maintenance teams to the locations of the defects, implying in the significant reduction of the other indicators dependent on this time, especially the Equivalent Duration of Interruption per Consumer Unit (DEC). The main contribution of this dissertation is the implementation of a meta-heuristic Variable Neighborhood Search (VNS), in order to determine the positions for the installation of the IFs, in order to reduce to the maximum the DEC estimation. In the methodology developed, the chosen network positions (sections) contemplate both the main trunk and the extensions, in addition to considering the influence of other protection devices in the network. In addition, the estimation of the average search time in the presence of these devices considers the failure rates and lengths of the stretches, extending the estimates made in other works. The results, obtained for a real feeder, in most of the studied situations, led to the allocation of IFs in sections of branches, bringing a more significant reduction in the Quality of Service indicators and demonstrating the effectiveness of the proposed methodology.