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1

Simulation and analysis of an isolated full-bridge DC/DC boost converter operating with a modified perturb and observe maximum power point tracking algorithm

Matias C. A., Medeiros G. P., Moraes P. H. F., Fernandes B. de A., Alves A. J., Calixto W. P., Furriel G. P.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 2

45--50

EN

The purpose of the present study is to simulate and analyze an isolated full-bridge DC/DC boost converter, for photovoltaic panels, running a modified perturb and observe maximum power point tracking method. The zero voltage switching technique was used in order to minimize the losses of the converter for a wide range of solar operation. The efficiency of the power transfer is higher than 90% for large solar operating points. The panel enhancement due to the maximum power point tracking algorithm is 5.06%.

2

Methodology for measurement the energy efficiency involving solar heating systems using stochastic modelling

Menita B. G., Medeiros G. P., Domingos J. L., Domingues E. G., Alves A. J., Faria A. F., Miguel M. L. S., Calixto W. P.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 1

42--51

EN

The purpose of the present study is to evaluate gains through measurement and verification methodology adapted from the International Performance Measurement and Verification Protocol, from case studies involving Energy Efficiency Projects in the Goias State, Brazil. This paper also presents the stochastic modelling for the generation of future scenarios of electricity saving resulted by these Energy Efficiency Projects. The model is developed by using the Geometric Brownian Motion Stochastic Process with Mean Reversion associated with the Monte Carlo simulation technique. Results show that the electricity saved from the replacement of electric showers by solar water heating systems in homes of low-income families has great potential to bring financial benefits to such families, and that the reduction in peak demand obtained from this Energy Efficiency Action is advantageous to the Brazilian electrical system. Results contemplate also the future scenarios of electricity saving and a sensitivity analysis in order to verify how values of some parameters influence on the results, once there is no historical data available for obtaining these values.

3

Increasing photovoltaic panel power through water cooling technique

Matias C. A., Santos L. M., Alves A. J., Calixto W. P.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 1

60--66

EN

This paper presents the development of a cooling apparatus using water in a commercial photovoltaic panel in order to analyze the increased efficiency through decreased operating temperature. The system enables the application of reuse water flow, at ambient temperature, on the front surface of PV panel and is composed of an inclined plane support, a perforated aluminum profile and a water gutter. A luminaire was specially developed to simulate the solar radiation over the module under test in a closed room, free from the influence of external climatic conditions, to carry out the repetition of the experiment in controlled situations. The first case study was published at EEEIC2016 conference where the panel was submitted to different rates of water flow, from 1 L/min to 4 L/min. In the test conditions without cooling apparatus, the panel reached about 70°C and produced approximately 63Wh. With the cooling apparatus with water flow rate of 2 L/min, the module reached about 50°C and produced approximately 77Wh. However, it has been observed that this water flow was overestimated. A second case study was carried out in order to perform the threshold between the flow and the energy produced. The best ratio was flow of 0.6 L/min and net energy of 77.41Wh. Gain of 22.69% compared to the panel without the cooling system. The best water flow rate was of 0.6 L/min and net energy of 77.41Wh. Gain of 22.69% compared to the panel without the cooling system.

4

Geoelectric method applied in correlation between physical characteristics and electrical properties of the soil

Filho A. M. S., Silva C. L. B., Oliveira M. A. A., Pires T. G., Alves A. J., Calixto W. P., Narciso M. G.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 2

37--44

EN

This paper presents the study of the relationship between electrical properties and physical characteristics of the soil. Measures of apparent electrical resistivity of the soil were made for different types of soil, varying moisture content gradually while maintaining a constant compaction, and then varying the compaction and relating it to a constant humidity. Development of a correlation surface is proposed in order to identify granulometry of the soil from moisture and compaction measurements. For the study of spatial variability, two areas were chosen to allow the change of moisture content and compaction in order to verify the measurement capacity of apparent electrical resistivity of the soil as methodology to identify change in soil dynamics. Results obtained show correlations among apparent electrical resistivity of the soil, moisture, soil compaction and clay content.

5

Calculation of the influence of slot geometry on the magnetic flux density of the air gap

Lima R. A. de, Coimbra A. C. P., Almeida T., Gomes V. M., Pereira T. M., Alves A. J., Calixto W. P.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 1

81--89

EN

The objective of this work is to investigate the influence of slotted air gap constructive parameters on magnetic flux density of rotating machines. For this purpose, different approaches were used to solve the air gap field diagram using finite element method and the magnetic field distribution uniformity was evaluated by Carter's factor calculation on two-dimensional and three-dimensional models. Sensitivity analysis of slot constructive parameters was performed and results show that slot geometry modifies the magnetic flux on air gap and shifts the air gap magnetic equipotential midline of double slotted machines. Finally, minimization of Carter’s factor on two-dimensional model presents an optimized slot geometry with a near uniform magnetic flux density distribution.

6

Analysis and monitoring of electrical grounding grid encapsulated with concrete: case study using simulation in finite element method

Pereira T. M., Lima R., Gomes V. M., Calixto W. P., Alves A. J.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 2

31--36

EN

This work study the influence of concrete, plaster, clay and others buried structures in grounding systems. Comparison of soil characteristics between dry and rainy seasons on different grounding systems. The study includes comparison of six different grounding system on dry season and wet season. Simulations in finite element method was performed for tree layer stratified soil and the electrostatic equipotential surfaces were mapped into the region of interest.

7

Reconditioning in synchronous operation with one parallel induction generator

Magalhães A. S., Moraes P. H. F., Silva A. H. F., Gomes P. H. G., Alves A. J., Calixto W. P.

Transactions on Environment and Electrical Engineering

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2016

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Vol. 1, No. 4

66--72

EN

The purpose of this paper is to compare mathematical modeling and practical bench in order to validate the electrical interactions between an induction generator and a synchronous generator. Two generators was connected to a common bus in steady state, subject to non-linear load. The results comparing modeling and bench tests show that the induction generator besides the active power increasing, has a better way for harmonic currents flowing in common bus. It was concluded that the induction generator repowering and attenuates current harmonic components present at the connection point, improving the network voltage profile.