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Item Aplicação da teoria da propagação do campo magnético na análise da máquina síncrona(Universidade Federal de Goiás, 2020-06-17) Alves, Renato Silva; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Paula, Geyverson Teixeira de; Silva, Rui Vagner Rodrigues daThis work presents a methodology of analysis of the smooth poles synchronous machine in steady state using the theory of magnetic field propagation to obtain the V curve for a given active operating power and various operating factors. This theory is based on the division of the synchronous machine into layers and the application of Maxwell’s equations. This methodology is capable of considering magnetic saturation and the anisotropy of electric steel. The predefined current model is used to estimate the radial and tangential flow density of the layer. The results obtained are compared with the Park equations in steady state. For the validation of the methodology, it was a threephase synchronous four-pole smooth generator is used. The results obtained were very promising when compared to the Park equations on a permanent basis.Item Aplicação da otimização por enxame de partículas com topologia "multi-ring" na estimação de parâmetros de linhas de transmissão(Universidade Federal de Goiás, 2015-11-03) Arruda, Sérgio Alexandre Martins; Calixto, Wesley Pacheco; http://lattes.cnpq.br/9073478192027867; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Martins, Alessandro; Garcés Negrete, Lina PaolaPresent world demands high availability of electricity for various equipment, in a context in which dominates the intensive use of technology. The electricity is transported from generation centers to consumers through Transmission Lines (TLs), which in Brazil have significant dimensions, given the continental size of the country, his predominantly hydro power plant generation, located long distances from major centers consumption. To ensure compliance of this high demand, often the electric power companies overload these TLs, generating undesirable effects, such as the formation of arrow in the conductors, for example. Monitoring of TL operating conditions is key part, therefore, to ensure system availability and security. This work aims in this context to present a method to assist in the monitoring of three-phase TLs of simple circuit based on measurement of electric and magnetic fields of the line and in application of an optimization procedure based on Particle Swarm Optimization metaheuristic, with a topology denominated Multi-Ring, to estimate simultaneously the values of current, voltage, cable-ground clearance of conductors and distance between phases, in a cross section of the line, assisting electric power companies and the National Electric System Operator (ONS) in the monitoring task. The good results achieved, combined with its simplicity of implementation compared to other methods and its robustness, indicate their suitability for estimating these parameters. Associated with this, the reasonably low times obtained in the execution make it promising for use by the electric power company and by the system operator as an auxiliary tool in monitoring TLs.Item Distorção harmônica de corrente produzida por inversores fotovoltaicos conectados à rede(Universidade Federal de Goiás, 2019-09-19) Castro, Felipe de Carvalho; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Belchior, Fernando Nunes; Marra, Enes GoncalvesThis investigation addresses the total harmonic distortion of current (THDi) produced by photovoltaic inverters installed in three different systems compounded by: a) photovoltaic generator rated at 3.055 kWp and photovoltaic single-phase inverter by Eltek, model Theia, rated at 2.9 kW; b) photovoltaic generator rated at 4.7 kWp and photovoltaic single-phase inverter by Eltek, model Theia, rated at 4.4 kW; c) photovoltaic generator rated at 41.3 kWp and photovoltaic three-phase inverter by Huawai, model SUN-2000-33KTL, with rated power at 33 kW. These three systems are installed on roof-tops at the Electrical, Mechanical and Computer Engineering School (EMC) of the Federal University of Goias (UFG). The percent THDi and 3rd and 5th order rms harmonic currents were measured with a power quality analyzer by Fluke, model 435-II, and a set of polynomial were achieved by means of linear polynomial regression in order to represent the behaviors of percent THDi and of 3rd and 5 th order rms harmonic currents as a function of global irradiance on horizontal plane and as function of inverter loads. The linear polynomial regression of grade three was sufficient to represent to represent the harmonic current behaviors produced by the solar inverters as a function of irradiance or load. In addition, the percent THDi and of 3rd and 5th order rms harmonic currents were classified into quartiles according to different ranges of solar irradiation on horizontal plane as well as different ranges of inverter loads, and the respective average values of rms harmonic currents and percent THDi to each one of the ranges were assessed. In conclusion, the Eltek inverter rated at 4.4 kW and the Huawei inverter rated at 33 kW meet the ABNT NBR 16149:2013 and IEEE 1547-2018 standard recommendations. The results regarding the Eltek inverter rated at 2.9 kW are not conclusive as the weather conditions at the moment measures were taken did not allow the inverter power to reach more than 62% of its rated power.Item Uso da transformada wavelet para análise dinâmica de um sistema fotovoltaico conectado à rede e sua interação com a rede elétrica(Universidade Federal de Goiás, 2018-03-09) Cesar, Thaissa de Melo; Pimentel, Sérgio Pires; http://lattes.cnpq.br/5676044617601856; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Pimentel, Sérgio Pires; Moreira, Alexandre Cândido; Lemos, Rodrigo Pinto; Marra, Enes GonçalvesThis work presents a study on the application of the wavelet transform in the monitoring and analysis of the power quality and in the detection of islanding conditions in distributed generation systems, addressing a grid connected photovoltaic system as a case study. Initially, an introduction about distributed generation systems, standards and requirements for operation was made. Next, the concepts and parameters related to electric power quality and islanding conditions are presented. Then a review of the wavelet transform is presented, showing the concept of multiresolution analysis and the main applications in the topic addressed. The wavelet transform is an important contribution to time-frequency localization methods for the analysis of transient signals. A multiresolution analysis was proposed through the discrete wavelet transform for voltage analysis at the common coupling point between the generation system and the electric grid. The standard deviation and the variation of the details coefficients of the wavelet transform were used for the detection and classification of disturbances. In the application of the method, pure sine-wave voltages with different types of disturbances were considered: voltage sag, voltage sweel, interruption, oscillatory transients and noise. And three cases of dynamic island detection were simulated with a grid connected photovoltaic system. The results obtained are presented and discussed for validation of the wavelet transform application in the analysis of grid connected photovoltaic systems.Item Análise de viabilidade técnica, econômica e ambiental de um projeto de eficiência energética associado com geração distribuída(Universidade Federal de Goiás, 2022-04-25) Faria, Adriano Ferreira de; Marra, Enes Gonçalves; http://lattes.cnpq.br/8463332056679918; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Marra, Enes Gonçalves; Belchior, Fernando Nunes; Viajante, Ghunter Paulo; Domingos, José LuisThis study focused on developing a sustainability project carried out in 11 Federal Institute of Education, Science, and Technology of Goiás (IFG) campuses, combining energy efficiency and distributed generation actions to optimize energy consumption by through the retrofit of the lighting system, installation of a photovoltaic generation system, energy monitoring, and qualification and training of teachers, students and employees, in compliance with the guidelines established by the National Electric Energy Agency (ANEEL) within the scope of the Public Call for Priority Projects for EE and Strategic R&D nº 01/2016 – “Energy Efficiency and Mini Generation in Public Institutions of Higher Education”. In the lighting system, 18,377 inefficient lamps were replaced by lamps with more efficient technology, with an energy saving of 867.9 MWh/year and a peak demand reduction of 309.6 kW. The proposed generation system aimed to install 3076 PV modules on the rooftops of selected campus buildings, totaling 1 MWp of installed power with an average annual power generation of 1736.9 MWh/year. The total project investment was USD 1,348,768.50 and the global cost–benefit ratio of the project was 0.68, which will result in annual savings of approximately USD 197,321.85. This corresponded to a 58% reduction in energy bills. The project proposed in this work was considered technically and economically viable within the scope of the Brazilian Energy. The estimate of avoided carbon emissions is also carried out, considering the methodologies used by the United Nations Framework Climate Change Convention (UNFCCC) for Clean Development Mechanism (CDM) projects that include energy efficiency activities and grid-connected renewable energy generation, resulting in an avoided emission of 983.36 tCO2 eq.Item Otimização aplicada ao projeto de enrolamentos de máquinas CA(Universidade Federal de Goiás, 2015-09-15) Franco, André Luiz Carneiro; Alvarenga, Bernardo Pinheiro de; Alvarenga, Bernardo Pinheiro de; Alves, Aylton José; Calixto, Wesley PachecoThis work presents an analysis and optimization metho dology for the AC machines stator windings design, based on magnetomotive force harmonic distortion study. For that, the three-phase double layer integral and fractional-slot windings are chosen. At first, magnetomotive force in conventional windings study is p erformed, comparing harmonic analysis by distortion and Fourier sp ectrum with the traditional calculation metho dology of winding factors. In relation to the metho d, the stator windings arrangement optimization using genetic algorithms is prop osed, in order to suggest alternative optimized layouts. The results are presented and discussed.Item Análise da inserção de sistemas fotovoltaicos conectados à rede elétrica da Ilha de São Vicente (Cabo Verde)(Universidade Federal de Goiás, 2017-12-11) Lima, Ciliana Karine Dias; Pimentel, Sérgio Pires; http://lattes.cnpq.br/5676044617601856; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Machado, Ricardo Quadros; Garcés Negrete, Lina Paola; Marra, Enes GonçalvesSustainable development is a present issue in world society and it is also a strategic challenge for Cape Verde’s energy policy in coming years because the large fragilities in the electrical system in Cape Verde such as, dependence on imports of fuels, geographical dispersion, the high costs associated with managing energy systems and the great energy waste. The bet on photovoltaic systems may be one of the alternatives to reducing these fragilities. In this context, the present work highlights the great existent potential for use of renewable energy focused on solar energy. The text describes incentives for the production of electric energy based on renewable sources and presents analyses on the implementation of two grid-connected photovoltaic systems in the island of São Vicente. One of the systems is a photovoltaic rooftop 19.8 kWp plant installed in a public secondary school building and the other system is 3 MWp photovoltaic power plant connected to electrical utility grid in São Vicente Island. The study included design, operation simulation of São Vicente Island distribution network in the presence and absence of photovoltaic systems and financial analyses in order to determine payback time, actual present value, intern return rate of investment and financial sensibility analyses to assess the influence of Wp cost and interest rate on the financial figures. The results show that the implementation of photovoltaic systems is attractive in financial and technical terms, the microgeneration system causes a large reduction in energy acquired by the network, and the large power plant has not worsened the appropriate operating voltage levels and decreased the system's active losses.Item Otimização do desempenho de enrolamentos de máquinas elétricas através de algoritmo de enxames de partículas multiobjetivo(Universidade Federal de Goiás, 2022-10-28) Martins, François de Souza; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Camargo, Ivan Marques de Toledo; Silva, Wander Gonçalves daThe present work demonstrates the optimization of the operation of electric machine windings. The parameters under study are the magnetomotive force and the end winding leakage inductance, obtained from the discrete distribution of conductors in the airgap. A multi-objective particle swarm metaheuristic optimization routine was proposed. The developed application is capable of generating the airgap conductor distribution for different machine configurations (single or poly-phase, single or double-layer, integral or fractional slots, full or shortened pitch, with the presence of empty slots, etc.), as well as the magnetomotive force curves and the end winding leakage inductance. Taking as an optimal winding the one that presents, simultaneously, less harmonic distortion of the magnetomotive force and less leakage inductance, the optimization by multi-objective particle swarm algorithm was used to obtain the optimal electrical machine parameter configuration.Item Aplicação da teoria de propagação do campo magnético na análise do motor de indução trifásico(Universidade Federal de Goiás, 2016-11-25) Namba, Luis Fernando Miyazaki; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Alves, Aylton José; Paula, Geyverson Teixeira deThis paper presents a methodology of three-phase induction machine in steady state, called Field Propagation Theory (FPT). The FPT is based on the engine division into layers and application of Maxwell’s equations, this methodology is able to consider the magnetic saturation and anisotropy of electrical steel and relate it to the motor equivalent circuit. The FTP has proposed two variations machine equation: The Induced Current Method (ICM) and the Predefined Current Method (PCM) which differ for the mode of obtaining the rotor current. To validate the TPC used two three-phase induction motors. The results of the proposed method were compared to those presented by the Finite Element Method (FEM) and were very promising.Item Dimensionamento de um sistema fotovoltaico conectado à rede a partir das características de inclinação e orientação dos módulos fotovoltaicos(Universidade Federal de Goiás, 2016-06-03) Paiva, Gabriel Mendonça de; Pimentel, Sérgio Pires; http://lattes.cnpq.br/5676044617601856; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Macêdo, Wilson Negrão; Marra, Enes Gonçalves; Pimentel, Sérgio PiresThis study aimed to evaluate the design of a grid-connected photovoltaic (PV) system according to the positioning of the modules which compose the generator depending on tilt and azimuth angles in Goiânia, Goiás. In that purpose, a review of the literature was carried out concerning the main methods of inverter sizing ratio analysis applied to grid-connected PV systems. Starting from an hourly average climate measurement database from Goiania, an algorithm was developed to search for the ideal local inverter sizing ratio, considering the use of polycrystalline module technology. The parameters used in the analysis were provided by the manufacturers of the componentes used in the grid-connected PV system in installation at the Electrical, Mechanical and Computational Engineering School (EMC) from Federal University of Goias (UFG), which nominal power is 33.84 kWp. An inverter sizing ratio band of 0.54 to 0.77 was obtained for a -90° to +90° azimuth angle variation and 0° to 90° tilt angle variation. The potential of financial indicators improvement was verified and it was estimated a potential reduction in the levelized cost of energy above 10% comparing the inverter sizing ratio improved system to an unitary inverter sizing ratio system.Item Machine learning methods applied to intraday solar forecasting for power system operation(Universidade Federal de Goiás, 2021-03-05) Paiva, Gabriel Mendonça de; Marra, Enes Gonçalves; http://lattes.cnpq.br/8463332056679918; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Mussetta, Marco; Marra, Enes Gonçalves; Pimentel, Sergio Pires; Brito, Leonardo da CunhaPrever o recurso solar é uma ferramenta essencial para sua integração com a rede elétrica. Esta tese foca em previsão solar intra-diária, com uma análise robusta de previsão de irradiância testada em múltiplas localidades e uma proposta de implementação de previsão de potência fotovoltaica (FV). Dois algoritmos de aprendizagem de máquinas são avaliados para previsão intra-diária da irradiância solar: programação genética multigene (PGMG) e redes neurais artificiais do tipo multilayer perceptron (MLP). PGMG é um algoritmo evolucionário e um método tipo "caixa branca" e é uma nova técnica na área. Os algoritmos de aprendizagem de máquinas também são comparados com um modelo de persistência inteligente (smart persistence) para prever a irradiância solar com dados de seis localidades. Os horizontes de previsão considerados são 15-120 minutos à frente. Os resultados das simulações mostram um aprimoramento consistente das previsões quando variáveis climáticas exógenas são adicionadas como entrada aos modelos, sendo 5.68% o aprimoramento pelo cálculo de erro médio absoluto (MAE) e 3.41% o aprimoramento pelo cálculo de raiz do erro quadrático médio (RMSE). Os resultados também mostram que localidade, horizonte de previsão e métrica de erro escolhida influenciam a dominância de acurácia dos modelos. Dois modelos de irradiância de céu claro foram implementados, mas os resultados indicam para uma baixa influência dos modelos na acurácia de previsão para previsões multivariadas por aprendizagem de máquinas. Em uma perspectiva genérica, PGMG apresentou resultados mais precisos e robustos que MLP em previsões individuais, provendo soluções mais rápidas. Entretanto, MLP apresentou mais precisão em previsões do tipo ensemble, porém estas apresentam também maior complexidade e maior custo computacional. A implementação de previsão de potência FV mostrou resultados consistentes, aprimorando valores de RMSE de previsões de persistência em 9.79%-23.75% para horizontes de 15-120 minutos.Item Cálculo de campos elétricos e magnéticos nas proximidades de linhas de transmissão: uma abordagem analítica e numérica(Universidade Federal de Goiás, 2017-09-26) Pereira, Arthur Melo; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Alves, Antônio Cesar Baleeiro; Paula, Hélder deIn a society dependent on electric energy for the execution of various daily activities, it is normal that its use is increasingly increasing over time. In order to carry out the transportation of all electric energy, it is essential to use transmission lines, which with increasing energy demand inevitably have tended to multiply throughout the world, and especially in Brazil, given its continental dimensions. Considering the function of the transmission lines for the electrical system, its importance in the context of the electric power supply is remarkable. However, the lines constitute one of the great emitting sources of electric and magnetic fields of low frequency, which has caused concern and has been motivating fact of several studies, like the realized in this work. Therefore, in view of the scenario presented in the previous paragraph, it is necessary to establish ways of calculating the fields more and more precisely. For the calculation of the electric field is used the Image Method, the Maxwell Potential Coefficients Method and the Coulomb Law, and for the magnetic field the Biot-Savart's Law is used. The results obtained for the electric and magnetic fields were for infinite rectilinear geometries, finite rectilinear and for the conductors taking the form of a catenary, the latter geometry being the most real model for the arrangement of the conductors in a line. In all cases treated, an analytical and numerical approach was performed, in order to allow the calculation of the three geometries with accuracy. Taking advantage of the methodology of calculation of the fields, in addition this work proposes a method of support to the monitoring of transmission lines. The method consists of using the Genetic Algorithm associated to the values of the electric and magnetic fields measured to determine the parameters of the line, such as: phase spacing, cable-soil height, equivalent conductor diameter, current and operating voltage. Given the simplicity of implementation when compared to other methods, the achievement of satisfactory results and the need for a single measuring device to monitor the transmission line, the proposed method proves to be viable and promising to carry out the line monitoring process.Item Aplicação de controlador preditivo baseado em modelo (MPC) para sistema de geração distribuída constituído por inversor trifásico a quatro braços(Universidade Federal de Goiás, 2017-08-07) Pinto, Lázaro Rubens Araújo; Pimentel, Sergio Pires; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4702368T9; Alvarenga, Bernardo Pinheiro de; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4784758Z9; Alvarenga, Bernardo Pinheiro de; Pimentel, Sérgio Pires; Pomilio, José Antenor; Marra, Enes GonçalvesThis work proposes an analysis of the closed-loop operation of a distributed generation system connected to a three-phase four-wire AC power system by a three-phase four-leg inverter. The modulation strategy adopted for this inverter is determined by the Model Predictive Control (MPC) method. Reasons for the use of this topology and the control method are discussed. The chosen structure for the MPC predictive control aims to supply of active and reactive power by the inverter in order to maximize the power factor measured by the four-wire AC source (Y-n). Four possible cases of operation are reported for the analysis of the proposal in the three-phase four-leg inverter and other two cases for a three-phase full-bridge inverter (3F) for comparison purposes. Based on the monitoring of the active powers involved and the other variables of interest, it was possible to exemplify the achievement of the proposed objectives and validate the adopted method, at least under modeling and software simulation level.Item Desenvolvimento de um sistema de ensaio de máquinas Brushless DC(Universidade Federal de Goiás, 2016-12-02) Prado, Renato de Almeida; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Monteiro, José Roberto Boffino de Almeida; Paula, Geyverson Teixeira deThe Permanent Magnet Brushless DC Machine has been used increasingly in numerous applications, such as in industry, transportation systems and wind energy conversion. Given this scenario and the need for knowledge of machine parameters for design purposes, performance analysis and operation of systems, this paper aims to present methodologies and the development of a test system. The test system is based on virtual instrumentation and aims to determine phase resistance, inductances, viscous and static friction coefficients, inertia, and electromotive force and torque constants. In many aspects, the test system is a tool that fills a gap in the area. To check the validity of the obtained parameters and to study machine's perfomance, computer simulations and load tests are performed.Item Análise dos efeitos da sujidade no sistema fotovoltaico de 34 kWp da EMC/UFG(Universidade Federal de Goiás, 2019-02-18) Romanholo, Pedro Victor Valadares; Marra, Enes Gonçalves; http://lattes.cnpq.br/8463332056679918; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Marra, Enes Gonçalves; Lemos, Rodrigo Pinto; Martins, Tatiana DuqueNeste trabalho, investigou-se o sistema fotovoltaico (SFV) instalado na Escola de Engenharia Elétrica, Mecânica e de Computação da Universidade Federal de Goiás. O estudo desenvolvido foi composto por duas abordagens, dirigindo-se primeiramente à caracterização físico-química da sujidade coletada da superfície dos módulos e, subsequentemente, atendendo ao estudo dos impactos na geração do SFV causados pelo encobrimento da superfície pelo material analisado. A caracterização físico-química da sujidade foi realizada por meio de medidas de Microscopia Eletrônica de Varredura com Espectroscopia de Energia Dispersiva, Difração de Raios-X, Termogravimetria com Análise Térmica Diferencial, Espectroscopia de Emissão Ótica com Plasma Indutivamente Acoplado e Espectrometria na Região do Infravermelho com Transformada de Fourier; além da caracterização físico-química, foram realizadas Análises Microbiológicas. Os resultados conjuntos destas análises foram interpretados à luz da literatura, permitindo identificar uma matriz rica em minerais e matéria orgânica para a composição da sujidade. Para avaliar os impactos na operação do SFV causados pela deposição deste elemento, amostras de vidro foram fixadas na superfície dos módulos, onde, durante um ano, foram realizadas, em laboratório, medidas mensais de Espectroscopia na Região do Ultravioleta-Visível para se averiguar as perdas na transmitância da superfície. Conjuntamente, dados de precipitação atmosférica e direção dos ventos foram interpretados paralelamente à análise mensal das lâminas. Os resultado obtidos apontam uma dependência substancial entre estes dois parâmetros e o acúmulo da sujidade na superfície analisada. Por último, quatro arranjos contendo 20 módulos cada, foram limpos mensalmente e comparados a outros dois conjuntos análogos que não foram submetidos à limpeza. O período de análise foi de 5 meses. A geração de energia e o rendimento global foram comparados para o par de módulos limpo-sujo associadamente com dados de precipitação atmosférica. Os resultados obtidos mostram que a limpeza da superfície dos módulos aumenta a geração e melhora o rendimento global, especialmente para este último, onde o foi observada uma elevação do parâmetro tão alta quanto 34% após limpeza.Item Aspectos luminotécnicos e da qualidade da energia de lâmpadas com tecnologia LED, fluorescente e vapor de mercúrio(Universidade Federal de Goiás, 2021-10-22) Rosa, Lucas Loures; Santos, Euler Bueno dos; http://lattes.cnpq.br/5005722083309404; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Santos, Euler Bueno dos; Belchior, Fernando NunesThe advancement of technology and power electronics has allowed a strong advance in large-scale production of electronic devices, which are incorporated into existing electrical systems, in most cases, so there is a change scenario in the type of interconnected load to the electricity distribution system. However, these devices can cause changes in the behavior of system components, caused by harmonics that can result in various damages to electrical equipment. These devices are attractive to consumers, as they offer the opportunity to consume less electricity, as in the case of lamps with active power less than conventional by more than 50%. The electrical characteristics of these devices must be better known so that the feeder circuits can be correctly dimensioned, as well as strategies to solve possible problems arising from unwanted effects. In this context, this work constitutes an analysis, performing confrontations between data obtained from traditional and more modern (“efficient”) devices, in a lighting system in the industrial sector. Among traditional devices, this research addresses fluorescent and mercury vapor lamps and, in the case of modern lamps, LED. In this sense, case studies are presented, with different types of technologies, which allow obtaining indicators of the power quality, with satisfactory precision and reliability. It is important to point out that the data referring to the experimental part were collected in an industrial environment, with the purpose of providing a qualitative and quantitative analysis, with the best possible fidelity.Item Estudo sobre o circuito equivalente da máquina de indução trifásica(Universidade Federal de Goiás, 2018-12-14) Silva, Andersom Gomes de Moura e; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Alves, Aylton José; Silva, Wander Gonçalves daThis paper presents a historical equivalent circuit of the three-phase induction machine, including the modern approach, the theory of the axes and the model in steady state. Also presented is an analysis that observes the consequent effects of the variation of the rotor resistance and the reactances of the stator and the rotor in several models of the equivalent circuit. A methodology is proposed for the determination of equivalent circuit parameters in order to represent the effect of harmonic components of the air gap magnetomotive force. The inclusion of the skin effect is discussed and it is proposed that inclusion of the equivalent circuit in which there is a representation of the harmonic effects. Is proposed equivalent circuits for solving the problem and computing the parameters and torque are illustrated. From this methodology a second analysis of the circuit is made by varying the same parameters of the first analysis. Two examples of engines are used to illustrate and validate the methodology and its analysis.Item Controlador robusto H-infinito para sistema fotovoltaico conectado à rede elétrica baseado em inversor multinível em cascata assimétrica(Universidade Federal de Goiás, 2019-05-20) Silva, André Felício de Sousa; Pimentel, Sérgio Pires; http://lattes.cnpq.br/5676044617601856; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Pimentel, Sérgio Pires; Borges, Renato Alves; Marra, Enes GonçalvesThis work presents a robust state feedback H-infinity current controller for a grid-connected single-phase photovoltaic system. The system contains two power stages, where the second stage corresponds to the DC-AC power conversion and is based on a 19-level asymmetrical cascaded multilevel inverter. Even though only the aspects of a single-phase, low power and low voltage photovoltaic system were directly addressed, the methodologies and conclusions described here can be extended to systems of higher voltage and power. The two main purposes of the proposed system is to operate in a grid-connected mode, providing power to a non-linear local load, and to comply with the performance requirements of the most relevant standards and regulations while injecting current in the power utility. To achieve this, a robust controller was developed, which is capable to deal with parametric uncertainties of the system and also presents a good disturbance rejection of the oscillations in the DC capacitors voltages of the inverter. The control strategy is divided in two parts: the control of the first power stage and the control of the current injection in the grid. Regarding the second stage controller, it was designed based on H-infinity optimization and eigenvalue placement problems, formulated through Linear Matrix Inequalities (LMIs). The simulation results were analyzed and indicate that the proposed system is capable to meet the stipulated performance requirements. The performance results of the proposed control system were then compared to the performances of a classical PI controller, regarding the robustness, and to an H-infinity resonant robust controller, with regards of the quality of the energy injected in the power grid utility.Item Tratamento de dados meteorológicos e análise de desempenho do sistema fotovoltaico da EMC/UFG(Universidade Federal de Goiás, 2019-03-08) Silva, Jéssica Alice Alves da; Marra, Enes Gonçalves; http://lattes.cnpq.br/8463332056679918; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Domingos, José Luis; Pimentel, Sérgio Pires; Marra, Enes GonçalvesThis work presents results from analyses of meteorological data acquired from the meteorological station and performance data acquired from the photovoltaic system, both installed at The School of Electrical, Mechanical and Computer Engineering (EMC) of The Federal University of Goias (UFG). The Meteorological station is composed of sensors that register solar irradiance on the horizontal plane, air temperature, pluviometric precipitation, relative air humidity, atmosphere pressure, speed an direction of the air. The meteorological data are acquire at one minute intervals and saved in a logger. The photovoltaic (PV) system comprises 133 PV modules rated at 235 W each, resulting in a system rated at 31,255 kW of total power. The analyses of meteorological data were based on a three-year sample base frotm 2016 to 2018 and PV system performance analyses were carried out based on data collected during the years 2017 and 2018. Irradiance and irradiation on tilted surface with inclination at the local latitude angle were estimated from irradiance on horizontal surface and then compared using to the following models: Iqbal (1983); Liu and Jordan (1960); Koronakis (1986); Jimenez and Castro (1982); Revfeim (1978) and Duffie and Beckman (1991). As a result, Duffie and Beckman model was adopted as the model to be used in this study. Both global irradiances and irradiations on horizontal as well as tilted surface with inclination at the local latitude angle were estimated by Duffie and Beckman model and compared to results from the Brazilian Atlas for Solar Energy and results from Radiasol2 Software. The PV system performance was assessed by some figures of merit, namely PV energy production (kWh); specific PV-productivity (YF in kWh/kWp); capacity factor and production ratio (PR). The PV energy production was obtained from inverter monitoring software provided by manufacturer. Energy production combined with meteorological data allows for computing the other figures of merit. Measured data were compared to theoretically figures of merit estimated from meteorological data and PV system technical characteristics. Furthermore, this study addressed some external influences on the modules such as soiling and shading. Yearly specific PV-productivity was 1209 kWh/kWp in 2017 and 1283 kWh/kWp in 2018; capacity factor was 13.8% in 2017 and 14.37% in 2018; and performance ratio was 63,93% in 2017 and 69,09% in 2018. In 2018 the PV modules were pressure washed monthly from June 23 rd , yielding an increase in all figures of merit in 2018 as opposed to those in 2017, highlighting the relevance of regular cleaning of modules for suitable PV system performance.Item Macro e micro modelo de planejamento para microrredes participantes de mercado local de energia(Universidade Federal de Goiás, 2022-03-21) Tonhá, Henrique Mesquita; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Kopcak, Igor; Silva, Luis Gustavo Wesz da; Marques, Thyago Carvalho; Silva, Luiz Carlos Pereira daMicrogrids (MRs) have intelligence and flexibility that provide the integration of renewable sources into their configuration. The complementary technical aspect between the different renewable sources and the storage schemes associated with a flexibility of energy contracts allows the existence of a local market involving MRs. This work aims to study two models of competition of MRs: macro and micro. The macro model deals with market competition between local MRs and the micro model, the competition between different generation sources. The virtual association of remotely installed MRs applied to a competition platform seeks to confer justice for these agentes in a macro market model competing with more centralized MRs in the network. By remunerating everyone involved, the model aims to reduce resistance and encourage the entry of new agents, especially those that enable the greatest gains in the quality of energy supply to the grid. From a constraint set and Karush-Kuhn-Tucker (KKT) conditions, it is possible to process the Nash equilibrium (EN) and Pareto efficiency (EP) points. A unique normalized EN can be obtained when the game is played in a convex environment with diagonally strictly concave or convex functions as the case in question. About the micro