Engenharia Elétrica

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http://repositorio.ufes.br/handle/10/17617

Programa de Pós-Graduação em Engenharia Elétrica

Centro: CT
Telefone: (27) 4009 2663
URL do programa: https://engenhariaeletrica.ufes.br/pt-br/pos-graduacao/PPGEE

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Agora exibindo 1 - 9 de 9

Controle parcial de potência em sistemas de energia através de um transformador de estado sólido híbrido
(Universidade Federal do Espírito Santo, 2024-06-10) Del Piero, Fádua Cozac Gonçalves; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
In recent years, there has been an increasing focus in science on engineering to optimize components and systems, driving advances in semiconductor technology in power electronics. This has enabled the use of higher switching frequencies, reduced volume, and increased efficiency. Within this context, microgrids, which rely on transformers and converters to integrate sources, loads, and systems, are gaining prominence. With the growing adoption of distributed energy sources, especially renewables, the use of efficient converters to control voltage, current, and power flow becomes crucial. However, the limitations of conventional transformers, such as limited voltage control and large volume, restrict system optimization. An alternative is the Solid-State Transformer, which offers advantages such as reactive power compensation, voltage regulation, and reduced size. Despite these benefits, the implementation of the Hybrid Solid State Transformer faces challenges, such as higher cost and lower efficiency. To overcome these difficulties, a hybrid topology is proposed that combines the conventional transformer with the Solid-State Transformer. In this work, a hybrid system was developed that uses the Solid-State Transformer for partial energy control, while the conventional transformer performs most of the transformation. Additional functionalities such as parallel and series active filters, reactive compensator, and dynamic voltage regulator were implemented. The system was analyzed under various load and supply profiles to validate the proposed topology and control, thereby demonstrating the feasibility of the configuration for a real-world situation
Detecção de eventos de obstrução em válvula no processo de lingotamento contínuo com uso de aprendizado de máquinas
(Universidade Federal do Espírito Santo, 2024-05-25) Diniz, Ana Paula Miranda; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
The continuous casting process, used in the manufacture of steel plates, is currently the most economical and efficient way of production within the industry. Although continuous casting is a widely used process, some problems associated with the process have not yet been resolved, one of them being the obstruction of the Submerged Entry Nozzle (SEN), which controls the flow of steel between the tundish and the mold. This obstruction, also called clogging, not only impairs the quality of the product but also results in lower process yield, resulting in losses. Thus, clogging detection is of fundamental importance, because control actions can allow the system to operate for a longer time. In this work, methodologies based on Machine Learning and Deep Learning are presented and compared to detect the occurrences of clogging from historical data of process variables. In general, the performance of the classifiers achieved very promising results in real data with unbalanced classes. In particular, the method employing spatiotemporal analysis, using four process variables, obtained a remarkably superior performance when compared to the others, reaching averages of Precision and Recall, respectively, of 95.53% and 97.33%. To reduce the false positive and negative rates, a post-processing heuristic was implemented and applied to the model output, achieving a Precision and a Recall, respectively, of approximately 98% and 99%. To the best of our knowledge, these results have never been found in the literature. Although a detailed comparison is unfeasible due to the differences between the datasets and their inaccessibility, the modeling proposed here reached higher performance levels when compared to the results found in the literature to solve this industry’s problem. The high and unprecedented results obtained in this work, therefore, will contribute both to the improvement of the quality of the final product and to the reduction of costs associated with steel production, since the more effective classification of clogging occurrences can help operators in the corrective action planning
Identificação e monitoramento de dormentes de ferrovias usando processamento de imagens
(Universidade Federal do Espírito Santo, 2017-05-29) Franca, André Stanzani; Vassallo, Raquel Frizera; 1º membro da banca
The railway is an important engine of the world economy. This means of transport more than 200 years old is efficient, safe and of great capacity and speed but still suffers from the difficulties of maintenance, mainly due to its assets of great extent, quantity, weight and geographic dispersion. In view of this, some initiatives in automatic inspection of railway assets have been developing. In particular, the inspection of railway sleepers (railway ties), which is sometimes done manually, needs development and consolidation. This dissertation presents a method for inventorying, identifying the type and some defects in sleepers based on image processing, heuristics and feature fusion in an unsupervised way. It uses Haar transform and integral images, as well as other image processing techniques such as edge detection and entropy computation along with aspects of railroad topology to achieve the proposed objectives. The algorithm was developed using real images of daily railway, previously unclassified, and that were subject to various noises and variations of a real railway operation. The method was validated through experiments with an image set that have approximately 33,000 sleepers. The results are promising and reach 97% accuracy in identifying the type of sleepers and reach 93% accuracy in identifying visible defects in sleepers.
Interface cérebro-computador baseada em potenciais evocados visuais em regime permanente para comando de uma cadeira de rodas robótica
(Universidade Federal do Espírito Santo, 2012-08-01) Müller, Sandra Mara Torres; Sarcinelli Filho, Mário; Bastos Filho, Teodiano Freire; 1º membro da banca
abstract
Projeto de Topologias Virtuais para Redes Opticas Multiserviço
(Universidade Federal do Espírito Santo, 2005-08-05) Almeida, Renato Tannure Rotta de; Calmon, Luiz de Calazans; 1º membro da banca
Optical communication systems have emerged as the best solution for large scale data transport network implementation, providing optical channels with very high bit rates and covering large distances with low error probability. The entire bandwidth of the optical fibers became available with the development of the wavelength division multiplexing (WDM) technology, which allows several channels of different wavelengths to share the same physical links. The increase in physical link capacity was not the only benefit of WDM. The development of WDM optical devices, e.g., optical switches, multiplexers, demultiplexers, and tunable devices, has allowed the implementation of wavelength-routed optical networks. In such networks, the optical channels, also called lightpaths, are not restricted to the physical link edges. Wavelength routing detaches the lightpath configuration, or virtual topology, from the physical topology, permitting lightpaths to optically bypass intermediate nodes, until it reaches the destination node. In this Thesis we propose a Mixed-Integer Linear Programming (MILP) formulation to design virtual topologies in wavelength-routed optical networks, considering as objective function the minimization of the traffic forwarded electronically at the network nodes. Our goal is twofold. Firstly, to reduce processing requirements of the electronic routers, and secondly, to get the most transparent traffic distribution for a given traffic matrix, using the available optical resources at the nodes. Traffic segregation in classes was also included in the formulation, allowing differentiated routing criteria to each class. The proposed formulation was applied successfully to reasonable sized networks yielding optimal solutions in few minutes. To the best knowledge of the authors, this is the first report of a large MILP formulation that optimizes virtual topology and traffic routing of optical networks with low computational cost.
Projeto fuse sensor para melhora da qualidade da continuidade de energia elétrica a partir da diminuição do indicador DEC
(Universidade Federal do Espírito Santo, 2024-05-27) Prazeres, Helder Batista de Boa Esperança dos; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
The electrical power distribution systems play a crucial role in social well-being and economic development, providing the foundation for essential services and business sus tainability. However, many components of these systems face technological obsolescence, contributing to power supply failures at critical moments. This situation is further exacer bated in Brazil due to the predominance of bare conductors in its distribution networks and the limited presence of underground networks, making them susceptible to failures caused by external factors. It is observed, however, that these failures in the electrical system can take time to be detected and located, leading to a deterioration in power quality, specifically in the system interruption time, which increases the financial compensation paid by utilities to consumers. To address these challenges, this dissertation presents the Fuse Sensor project, developed in partnership with the company SEVEN (Seven Science Systems Ltda), as an innovative solution incorporating the concepts of Smart Grids and IoT (Internet of Things) technology for the faster location and repair of faults, thus enabling improvements in the efficiency and reliability of electrical systems. The Fuse Sensor is designed to meet the present and future needs of the electrical system, focusing on reducing the SAIDI (System Average Interruption Duration Index), and providing significant gains in compensations. The master’s project approach is structured into three distinct stages: in the first stage, the conception and construction of the Fuse Sensor project are presented, along with the testing procedures; in the second stage, validations of the Fuse Sensor project are conducted, including a comparison of the effectiveness of the communication technologies LoRa, SigFox, and FSK; and finally, in the third stage, an economic analysis is carried out, considering not only the acquisition costs of the innovative equipment but also its economic feasibility for the utilities. By addressing these aspects comprehensively, the Fuse Sensor project aims not only to mitigate the repair time of power supply interruptions but also to promote significant improvements in the quality and reliability of the electrical service. Combining technological innovation and detailed economic analysis, the project seeks not only to meet the current demands of the electrical sector but also to pave the way for a more efficient and sustainable future
Reator eletrônico microcontrolado de alto fator de potência para lâmpadas de alta intensidade de descarga
(Universidade Federal do Espírito Santo, 2005-11-24) Orletti, Renato; Có, Márcio Almeida; Vieira, José Luiz Freitas; 1º membro da banca
This work presents an overview about the High intensity discharge (HID) Lamps, showing its operation, the lamps variety and the peculiarities of this drive. The drive with electromagnetic ballast and electronic ballast are studied to verify advantages and disadvantages. After the analysis of electromagnetic and electronic drives, an electronic ballast is proposed. A prototype was implemented to verify the ballast performance. The experimental results have proved the viability of the electronic ballast proposed, emphasizing the reduced number of components used to make the prototype.
Sensores de nível de interface água-óleo em fibra óptica baseados em grades de Bragg
(Universidade Federal do Espírito Santo, 2020-05-27) Ludke, Fabio Giesen; Co-orientador1; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador2; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador3; https://orcid.org/; http://lattes.cnpq.br/; Co-orientador4; ID do co-orientador4; Lattes do co-orientador4; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; Orientador2; https://orcid.org/; http://lattes.cnpq.br/; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 2º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 3º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 4º membro da banca; http://lattes.cnpq.br/; 5º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 6º membro da banca; https://orcid.org/; http://lattes.cnpq.br/; 7º membro da banca; https://orcid.org/; http://lattes.cnpq.br/
This Master Thesis presents the study of fiber Bragg grating (FBG) sensors applied in the measurement of water and oil interface level. Using industrial rubber diaphragms, which has a fiber Bragg grating installed inside, it is possible to measure the level of interface water-oil. The measurement is performed by monitoring the pressure change on each diaphragm caused by the variation in the interface level. The FBG sensors are non-conductive, resistant to electromagnetic interference (EMI) and they are intrinsically safe to be installed in explosive environments. Techniques of FBG inscription known as phase mask and plane-by-plane have been used to manufacture the fiber sensors. Using a spectrometer, the coupled light propagating through the fiber sensor can be interrogated. The analyzes are performed searching for the central wavelength for each FBG used. The stress on the FBG causes a shift in the central wavelength proportional to the level of the interface between the different fluids, for example water and oil. Thus, as water and oil have different densities and depending on the amount of material that is inside the tank, the diaphragms with FBG undergoing higher or lower deformation and causing a proportional wavelength shift variation of the FBG peak. The main materials used in the production of the FBG sensors are silica optical fiber, thermoplastic polyurethane and nitrile rubber. Nitrile rubber corrosion resistant, including use in the oil industry. A methodology was developed for production of FBG sensors with diaphragms printed on the 3D printer and using the nitrile rubber vulcanization. The sensor developed through the vulcanization of nitrile diaphragms with FBG inside was produced using a press system with temperature control. The influence caused by the variation in the diaphragm thickness is observed in the tests with diaphragms produced on 3D printer. This variation doesn’t change the linearity of the system, but change its sensitivity. The measured sensitivities were 7.5 pm/kPa and 5.2 pm/kPa for the diaphragm of 1.2 mm and 2 mm, respectively. The operating range of this interface level sensor varies from 0 to 78 cm. The resolution of the system is approximately 0.01 cm. For interface levels ranging from 0 cm to 78 cm, the standard deviation varied from 0.13 to 0.28, respectively. The average differences calculated for interface levels varying between 0 cm and 78 cm, resulted in standard deviation ranging from 1.09 to 0.43, respectively. It was possible to identify the oil and water interface level in the tests with nitrile diaphragms. As a result, an equation was obtained, where it is possible to determine the interface level through the diaphragm deformation, showing this system has potentiallity to evolve to a product in the near future
Uma Arquitetura para Ambientes Virtuaisde Conveniencia-Uma proposta Baseada emSistemas Multiagentes
(Universidade Federal do Espírito Santo, 2006-09-29) Jose Francisco de Magalhaes Netto; Orientador1; 1º membro da banca
abstract

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