Navegando por CNPq "CNPQ::ENGENHARIAS::ENGENHARIA ELETRICA::CIRCUITOS ELETRICOS, MAGNETICOS E ELETRONICOS"

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Acesso aberto (Open Access)
Análise de desempenho de pará-raios de ZnO sob diversos cenários de poluição utilizando método de elementos finitos
(Universidade Federal do Pará, 2022-08-16) LISBOA, Mellina Modesto; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
Metal-Oxide Surge Arrester is one of the protection devices of vital importance for Electric Power Systems and the equipment that composes them, since it ensures the reliability and continuity of operation of these systems based on their ability to attenuate transient overvoltage resulting from lightning strikes or switching surges. This equipment is formed by blocks of variable ZnO resistors, associated in series or in parallel, whose voltage-current curve presents high non-linearity. In view of the relevance of using the lightning rod, it is necessary to investigate its operating conditions. In the literature, several procedures and techniques are found for this purpose, among which monitoring through measurement and analysis of the leakage current stands out, since this represents one of the main factors that contribute to the degradation of this equipment. Given this context, the present master's dissertation implements a two-dimensional model of a 30 kV Zinc Oxide lightning arrester, using the Finite Element Method, to obtain the leakage current curves, electrical potential distributions, current density and that of electric field lines, when this device is subject to voltage variations and pollution conditions. The results show a significant increase in these measured quantities as the level of pollution intensifies, as well as with the increase in voltage levels.
Acesso aberto (Open Access)
Estratégias de planejamento para otimização do consumo residencial de energia elétrica: uma abordagem baseada em smart home e sistemas fuzzy
(Universidade Federal do Pará, 2017-08-04) ANDRADE, Sérgio Henrique Monte Santo; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
Residential energy consumption has grown steadily over the last decades, becoming a problem for companies in the electricity sector, for consumers and for the environment. The traditional measurement systems are not sufficient and have limitations in providing adequate real-time information about consumption. As also, they are not prepared to deal with variable energy costs in the context of a market with dynamic prices that depend on the energy mix. The future of electric grid, called Smart Grid, will not only be designed with measurements based on the residences, but also on the individualized equipment consumption level. From the residential side, consumers generally suffer from a lack of information on the specific equipment energy consumption impact and, consequently, on the required behavior to reduce its consumption. In this context, this work aims on a smartphone monitoring system concept, to control energy using fuzzy logic, in order to provide to the user ways to maintain his energy consumption, through consumption profiles, within the user-defined consumption patterns. The energy reduction demand through the consumption profiles working with habitant dependence degree on the electrical equipment present in the residence, promote a smaller impact on inhabitant well-being and the daily life.
Acesso aberto (Open Access)
Implementação e testes de campo de um ESP digital
(Universidade Federal do Pará, 2010-05-18) GOMES, Marcus Ciro Martins; BARREIROS, José Augusto Lima; http://lattes.cnpq.br/1246564618922453; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608
This work presents the development and implementation as well as the results of field tests of a power system stabilizer (PSS) designed with digital control method for damping electromechanical modes of oscillation observed for signs of electrical power measured in a generating unit of 350 MVA of Tucuruí power plant. It is presented and applied the methodology of identifying linear parametric models such as auto regressive with exogenous inputs (ARX) for estimation of models with the ability to capture the relevant information (natural frequency and damping) of dominant electromechanical modes of the system. In possession of ARX parametric model is done then the synthesis of digital damper control law for the ESP, using the technique of pole displacement of the closed loop transfer function. For the synthesis of digital control law, we used a canonical structure type RST. For the field tests, the control law digital ESP buffer was coded in C language and embedded in a hardware prototype of which is based on model DSPIC 30F3014 microcontroller, which incorporates a large number of peripherals for data acquisition and communication. In order to evaluate the performance of the digital PSS developed, experimental tests were performed in a generating unit of 350 MVA power house number 1 from Tucuruí power plant. The stabilizer acts carried out by adjusting the reference voltage regulator automatic voltage of the respective generating unit in accordance with the oscillations observed by measuring the electrical power generator stator. The results of field tests showed an excellent performance of ESP digital damping of electromechanical mode of natural frequency of approximately 1.7 Hz, observed in the field trial.
Acesso aberto (Open Access)
Uma metodologia para predição do campo elétrico de radiodifusão sonora em ondas médias utilizando inferências bayesianas
(Universidade Federal do Pará, 2013-06-11) COSTA, Juliana Santiago Monteiro; ARAÚJO, Jasmine Priscyla Leite de; http://lattes.cnpq.br/4001747699670004; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
The adoption of digital sound broadcasting systems, which are under testing in the country, allows new studies aimed a better planning for the implementation of new stations, which means to reassess the major existing radio propagation models or propose new alternatives to meet demands inherent in digital systems. The current models, as Recommendations ITU-R P. 1546 and ITU-R P. 1812, do not match closely with the reality of some regions of Brazil, especially in the tropical regions, such as the Amazon Region, due to the high rainfall and the vast existing flora. Using models suited to the propagation channel, it becomes feasible to develop planning tools covering most accurate and efficient. The use of these tools is applicable both to ANATEL, for the elaboration of the basic plans, as distribution channels for broadcasters. This paper presents a methodology using a computational intelligence based in Bayesian Networks for prediction of electric field intensity, which can be applied to planning or expanding coverage areas in broadcasting systems for frequencies in the range of medium wave (300 kHz to 3 MHz). This methodology generates electric field values estimated from the values of terrain altitude (through analysis of conditional probability tables) and provides a comparison of these values with the measured electric field. The data used in this study were collected in Brazil’s central region, nearby the city of Brasilia. The transmitted signal was an AM radio signal transmitted at a frequency of 980 kHz. With the data collected during the measurement campaigns, simulations were performed using conditional probability tables generated by Bayesian Networks. Thus, it’s proposed a method for predicting values of electric field based on the correlation between the measured electric field and the altitude through the use of artificial intelligence. Compared to numerous studies in the literature that have the same goal, the results found in this study validate the use of the methodology to determine the electric field in medium wave radio broadcasting using Bayesian Networks.
Acesso aberto (Open Access)
Proposta de novas técnicas de modelagem para estudo da redução do potencial de passo e aterramento por elementos de circuito
(Universidade Federal do Pará, 2007-08-01) ARAÚJO, Humberto Xavier de; SOUZA SOBRINHO, Carlos Leônidas da Silva; http://lattes.cnpq.br/1450994881555781
This work presents new techniques to reduce the step potential in grounding systems, as well as analysis regarding others present in the literature. For this goal, some resources were employed, such as to bent the mesh grounding borders (Umbrella Model) and the use of ramifications on the grounding rods (Fractal Model). The obtained results clearly show that the proposals are promising and efficient, mainly when dealing with a problem of large importance for people and equipment security. Reductions up to 85% in the step potential were obtained. It is also proposed here, the employment of lumped parameteres circuit elements, aiming at a ground system model capable to operate in any kind of the existing grounds. In order to analyze the structures, a software was utilized in which Maxwell’s equations are numerically solved by the FDTD Method associated to the UPML technique, and thin wires in a lossy medium.
Acesso aberto (Open Access)
Simulação de transporte eletrônico em dispositivos unimoleculares baseados em indicadores de pH
(Universidade Federal do Pará, 2009-02-03) GRANHEN, Ewerton Ramos; DEL NERO, Jordan; http://lattes.cnpq.br/5168545718455899
In recent decades, several researchers have tried employ molecules in electronic devices of nanoscale. For this reason, different electro / optical parameters, governing the electronic transport in organic molecules, need to be analyzed. In this work was developed a charge transport study to the composed propyl red, popularly used as pH indicator. The motivation to study it results from its structure formed of donor-acceptor subunits, coupled via azo group (N = N), a well known feature in molecular rectifiers. The methodology used to treat the system in equilibrium is based on Molecular Mechanics and Hartree-Fock methods. However, another method, based on the Landauer-Büttiker formalism, to non-equilibrium system was employed. Through these methods, the feature curves of molecular system were drawn and compared. The result of comparison lowed explain the phenomena that govern the electronic transport in nanostructure. Besides that, was analyzed the effects of metal contacts, connected on molecules in presence of external electric field.
Acesso aberto (Open Access)
Smartcom: uma arquitetura inteligente de gerenciamento de consumo de energia para smart home
(Universidade Federal do Pará, 2017-08-25) OLIVEIRA, Edvar da Luz; FRANCÊS, Carlos Renato Lisboa; http://lattes.cnpq.br/7458287841862567
With advances in information technology for a variety of areas, such as health and wellness, Smart Home based solutions using Internet of Things (IoT) technologies are gaining in popularity, including energy-saving alternatives based on Home Energy Management Systems (HEMS). This thesis defines an innovative architecture, called SmartCoM, which is implemented to monitor and manage residences using IoT technologies. Such a strategy involves defining the parameters that can affect the interoperability between measurement, management and the layers of data communication, which are the resources necessary for the hardware devices to perform the intended monitoring and measurement. In addition, an interface is defined by a middleware layer to integrate the management of external installations and the visualization of data through cloud services. The SmartCoM architecture is defined end-to-end in detail from the consumer's point of view and optimization strategies are employed for both the end customer and the utility. In order to evaluate the proposed architecture, a case study was elaborated, from which the viability of developing solutions for Smart Home according to the requirements described in SmartCoM is observed.
Acesso aberto (Open Access)
Utilização de métodos ativos na transformação de um prédio em um edifício de energia zero: estudo de caso da biblioteca central da Universidade Federal do Pará
(Universidade Federal do Pará, 2020-05-06) ALBUQUERQUE, Bruno Santana de; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
This dissertation proposes an energetic evaluation of a University Building transformation into a Zero Energy Building (ZEB), by using active methods such as Lighting System (LS), Photovoltaic System (PV) and Storage System (SS), and presents its application in the form of a case study. The purpose of this study is to analyze the energy balance between the UFPA Central Library, the implementation of the LS, the PV, the distribution system and the SS, aiming at the load autonomy. Satisfactory results were obtained for different scenarios created by the load variability, according to the university calendar, and the photovoltaic generation intermittency. The proposed LS reduced the building consumption by 44%. Using the PV system generates enough energy to supply most of the building load, however only 53% of this energy benefits the building, the energy surplus supplies other university loads. However, the SS integration allows the building to benefit 77% of the generated energy. Therefore, the proposed systems provide the ZEB concept to the study case building.