Artigos em Revistas

O vertiginoso crescimento do uso de veículos elétricos e da instalação de eletropostos cria a necessidade de se pesquisar formas de proteger essas estruturas contra danos provenientes de descargas atmosféricas, principalmente em regiões do planeta onde a ocorrência de descargas atmosféricas é abundante, como na Amazônia. Tais estruturas apresentam inúmeros componentes eletrônicos sensíveis, que podem ser facilmente danificados. Neste trabalho, avalia-se se duas estações de carregamento de veículos elétricos do Centro de Excelência em Eficiência Energética da Amazônia – CEAMAZON – estão adequadamente protegidas contra descargas atmosféricas. Para isso, tomou-se como base os estudos realizados na Ásia, Europa, além da norma brasileira. Constatou-se que, apesar do prédio do CEAMAZON possuir um SPDA adequado, os eletropostos encontram-se vulneráveis, principalmente contra os efeitos indiretos causados pela ocorrência de descargas atmosféricas nas suas proximidades.

IGOR RODRIGUES DE NARDI, ADÔNIS FERREIRA RAIOL LEAL, MARIA EMÍLIA DE LIMA TOSTES, ANDRÉIA ANTLOGA DO NASCIMENTO

The high amount of energy consumption demanded by buildings entails the worsening of several environmental issues. Therefore, actions to make use of this resource more efficient become necessary. The most used methods of Building Energy Modeling (BEM) designated to assess the functionality of such actions are excessively complex and, in many cases, generate unreliable results. Thus, this work aims to elaborate an approach based on Building Information Modeling (BIM) to improve energy efficiency in buildings in a simplified and user-oriented manner. For this purpose, a case study was developed in which two classrooms of an educational building, located in the Amazon region – Brazil, were subjected to three-dimensional modeling and energy simulations in BIM software. In addition to evaluating the classrooms’ current performance regarding daylight, thermal conditions and energy consumption, such simulations intended to assess the implantation of two strategies that sought to reduce energy consumption and maintain thermal and visual comfort by taking advantage of daylight and natural ventilation. Besides of energy saving, such strategies were chosen as they promote Indoor Environmental Quality (IEQ) and help to mitigate the indoor transmission of infectious agents, which is fundamental due to the COVID-19 pandemic scenario, especially in educational environments. The results showed that the strategy based on daylight contribution generated energy savings of around 8% for one of the rooms, and 12% for the other, while the one that exploited the use of natural ventilation was able to reduce energy consumption by about 7% for one of the rooms, and 9% for the other. Therefore, this research presents an important contribution as it provides an intelligible workflow that makes the energy simulation process friendlier and more intuitive and that was able to generate plausible results using BIM-BEM interoperability.

JOÃO GABRIEL CARRIÇO DE LIMA MONTENEGRO DUARTE, BRUNO RAMOS ZEMERO, ANA CAROLINA DIAS BARRETO DE SOUZA, MARIA EMÍLIA DE LIMA TOSTES, UBIRATAN HOLANDA BEZERRA

The search for more competitive equipment in the global market has led to the implementation of new materials and technologies in the search for greater energy efficiency. This is certainly a guideline followed by the electric motor industry that has introduced new technologies in rotating machines, such as the permanent magnet motor, evolving into increasingly efficient motor classes. However, subjecting these efficient motors under nonideal electric grid power conditions, such as voltage unbalance, can cause these efficient machines to generate additional distortions in the voltage and current waveforms, which in turn not only affect the performance of electric motors themselves but also that of the electrical system in general. This work presents a comparison between energy efficiency gain and the corresponding power quality degradation through a detailed harmonic analysis of the effects of voltage harmonics and voltage unbalance in three 0.75-kW electric motors classes: IE2, IE3, and IE4, The results show that for increasing percentages of a specific harmonic distortion, other harmonics are also increased in the higher efficiency electric motors sample analyzed, and similar responses were also observed for large percentages of voltage unbalance, mainly in the line-start permanent magnet motor class IE4. The results achieved are interesting but rigorously reflect only the tested motor sample and cannot be generalized to all motors, in other power ranges, of the respective motor classes tested. For generalization, exhaustive tests must be accomplished to formulate general conclusions according to the electric motors' classes commercially available.

JONATHAN MUÑOZ TABORA, MARIA EMÍLIA DE LIMA TOSTES, UBIRATAN HOLANDA BEZERRA, EDSON ORTIZ DE MATOS, CARLINDO LINS PEREIRA, THIAGO MOTA SOARES

Photovoltaic systems can strengthen the energy matrix aiming at energy sustainability, however, their intermittence, the availability time frame and seasonality effects are complicating aspects for the operation of these systems. To mitigate such problems, a possible measure is the operation of hybrid systems (HS) associated with storage systems to meet the energy demand. This study presents real operational scenarios for the management of a hybrid mini-grid installed in the Amazon region in Brazil, capable of managing energy supply and demand, changing the generation curve, reducing fossil fuel consumption and energy costs, in addition to providing flexibility and operational safety to the electrical operating under on-grid or off-grid conditions. Through technical and economic analyses, the objective of this study is to show that hybrid systems can be implemented in small and medium consumers, in addition to generating a new market option for utilities. This research evaluates the operation of HS concurrently with the electrical grid and the results show that the system meets the technical requirements, in addition to bringing financial and ecological benefits. This information can support the decisions of consumers, utilities and energy operators for the development of the national market for on-grid and off-grid HS.

JONATHAN MUÑOZ TABORA, ULISSES CARVALHO PAIXÃO JÚNIOR, CARLOS EDUARDO MOREIRA RODRIGUES, UBIRATAN HOLANDA BEZERRA, MARIA EMÍLIA DE LIMA TOSTES, BRUNO S. DE ALBUQUERQUE, EDSON ORTIZ DE MATOS, ANDRÉIA ANTLOGA DO NASCIMENTO

The electrical insulation is one of the main sources of failures in hydro-generators, therefore it is important to research the insulation system of stator bars. In this paper, it is developed a steady-state multiphysics analysis of a stator bar using the Finite Element Method to assess its steady-state behavior in the electrical, magnetic and thermal domains. Different aspects are analyzed in simulations, such as capacitance, mechanical stress and thermal effects. Numerical results are compared with experimental measurements for validation.

JOSÉ WILLIAM RIBEIRO BORGES, WELLINGTON DA SILVA FONSECA, RAMON C.F. ARAÚJO, FERNANDO DE SOUZA BRASIL

The growth in global electricity demand has expanded the search for new energy resources. Renewable sources such as photovoltaic (PV) systems have proven to be major alternatives. PV generators connected to distribution grids have exhibited significant growth in the last decade, so it is essential to analyse the impacts resulting from this increase. This work investigated the influence of high PV system penetration in distribution grids in terms of harmonic levels. In particular, this study addressed the distortions in voltage and current waveforms in the presence and absence of PV generators connected to a distribution grid. Additionally, the total harmonic content and the individual harmonic frequencies of voltage and current were analysed. This study was performed with an IEEE 37 bus distribution system and the Open Distribution System Simulator software (OpenDSS). The results show that the voltage limits of some phases far away from a substation can exceed the limits. Furthermore, the total harmonic distortion (THD) and individual harmonic distortion (IHD) levels for voltage and current were significantly high for harmonics of the 3rd, 5th, and 7th orders, where current levels violate the standard levels.

JORGE LUIZ MOREIRA PEREIRA, ADÔNIS FERREIRA RAIOL LEAL, GABRIEL OLIVEIRA DE ALMEIDA, MARIA EMÍLIA DE LIMA TOSTES

The main equipment responsible for connection and transmission of electric power from generating centers to consumers are power transformers. This type of equipment is subject to various types of faults that can affect its components, in some cases also compromising its operation and, consequently, the electric power supply. Thus, in this paper, electromagnetic, thermal, and structural analysis of power transformers was carried out with the objective of providing the operator with information on the ideal moment for performing predictive maintenance, avoiding unplanned shutdowns. For this, computational simulations were performed using the finite element method (FEM) and, from that, the different transformer operation ways, nominal currents, inrush current, and short-circuit current were analyzed. In this perspective, analyses of the effects that thermal expansion, axial forces, and radial forces exerted were carried out, contributing to possible defects in this type of equipment. As a study object, simulations were carried out on a 50 MVA single-phase transformer. It is important to emphasize that the simulations were validated with real data of measurements and with results presented in the current literature.

ANTONIO RONIEL MARQUES DE SOUSA, MARCUS VINÍCIUS ALVES NUNES, WELLINGTON DA SILVA FONSECA, RAMON CRISTIAN FERNANDES ARAUJO RAMON CRISTIAN FERNANDES ARAUJO SCIPROFILESSCILITPREPRINTS.ORGGOOGLE SCHOLAR, DIORGE DE SOUZA LIMA

Important industrial applications are based on magnetohydrodynamics (MHD), which concerns the flow of electrically conducting fluids immersed in external magnetic fields. Using the Finite Volume Method, we performed a 3D numerical study of the MHD flow of a conducting fluid in a circular duct. The flow considered was laminar and fully developed. Along the initial section of the duct, there were magnets placed around the duct producing magnetic fields in the radial direction. Two arrangements of magnetic field orientation were considered: fields pointing toward and away from the duct’s center alternately, and all fields pointing toward the duct’s center. For each arrangement of magnets, various intensities of magnetic fields were considered to evaluate two effects: the influence of the magnetic field on the flow velocity, and the influence of the flow velocity on magnetic field induction. It was found that for the second arrangement of magnets and Hartmann numbers larger than 10, the flow velocity was reduced by as much as 35%, and the axial magnetic induction was as high as the field intensity applied by each magnet. Those effects were negligible for the first arrangement and low fields because of the distribution of field lines inside the duct for these situations.

WELLINGTON DA SILVA FONSECA, RAMON C. F. ARAÚJO, MARCELO DE OLIVEIRA E SILVA, DANIEL ONOFRE DE A. CRUZ

Este trabalho tem por objetivo analisar a influência da definição do fator de potência em estudos de fluxo de carga com o objetivo de realizar o cálculo de perdas técnicas ativas e reativas, utilizando um sistema teste simplificado e um sistema de distribuição real, pertencente à área de concessão da distribuidora do estado do Pará. Será apresentada a importância de se utilizar um fator de potência que melhor represente a característica da carga da área de concessão e um algoritmo que configure o fator de potência das cargas de acordo com os dados de medição em alimentadores ou transformadores de distribuição. Os resultados mostraram as diferenças no cálculo de perdas técnicas quando da utilização do fator de potência regulatório e o fator de potência real verificado nas cargas.

JOÃO V. DOS R. ALVES, CARLOS E. M. RODRIGUES, THIAGO M. SOARES, MARIA E. DE L. TOSTES, UBIRATAN H. BEZERRA, ELAINE C. S. DA SILVA, CARLOS J. DA S. MOURA, MICHEL F. RENDEIRO

O presente trabalho utiliza o software OpenDSS para modelar uma rede elétrica de distribuição, capaz de simular o comportamento da rede elétrica e os impactos na qualidade de energia elétrica de acordo com as diferentes topologias de transformadores, cargas e fontes de geração distribuída em que uma rede elétrica pode ser submetida. Como estudo de caso, o artigo utiliza dados reais da rede da Universidade Federal do Pará e a inserção de geradores solar fotovoltaicos em diferentes pontos da rede, como demonstração do impacto na redução da potência ativa, na elevação do nível de tensão e na redução de perdas elétricas de acordo com a inserção da geração distribuída (GD) na rede elétrica estudada.

VINICIUS BORGES ANDRADE, ULISSES C. PAIXÃO JR., CARLOS E. MOREIRA, THIAGO M. SOARES, JONATHAN M. TABORA, MARIA EMÍLIA DE L. TOSTES, UBIRATAN H. BEZERRA, BRUNO S. ALBUQUERQUE, LUCIANO DA S. GOUVEIA