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Navegando por Assunto "Transformadores de potência"

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    Análises multifísica via método de elementos finitos para o auxílio à manutenção preditiva em transformadores de potência.
    (Universidade Federal do Pará, 2018-09-21) SOUSA, Antonio Roniel Marques de; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447
    The National Interconnected System (NIS) is an organ of fundamental importance in the Brazilian panorama. Its function is to electrically connect generating centers and consumer centers, whether they are business, commercial or residential. The main equipment responsible for the connection and transmission of electric power from the generating centers to the consumers are the power transformers. This equipment is subject to several types of faults that can affect its components, in some cases compromising the operation of this equipment, and consequently the supply of electric energy. In this work, a multiphysical analysis is performed on power transformers, coupling thermal and structural electromagnetic simulations with the objective of providing the operator with information about the ideal moment for performing predictive maintenance, avoiding unplanned shutdowns. For this, computational simulations using the Finite Element Method (FEM) were used and from this, we analyzed the different situations that these equipments can be submitted, in the nominal condition, as well as extreme conditions of operation like current of inrush and current short-circuit. In this perspective, analyzes of the effects that the thermal expansion and the axial forces and radia exerted contributing to possible defects in these equipments were carried out. As a study object, the simulations were performed in a 50 MVA single-phase transformer, which is an equipment that is in operation in the northern region of the country. For a more validation of the methodology used in this work the simulations were validated with real measurement data and with results present in current literature. In this way, this work presents a methodology that can help the technical framework of an industry in the decision of the appropriate moment of stop in a power transformer for the accomplishment of predictive maintenance.
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    Detecção e localização de descargas parciais em transformadores de potência utilizando sinais acústicoas transitórios e o método GSPS
    (Universidade Federal do Pará, 2015-01-29) ARAÚJO, José Weliton de Oliveira; FARIAS, Rubem Gonçalves; http://lattes.cnpq.br/3261608243924147; OLIVEIRA, Rodrigo Melo e Silva de; http://lattes.cnpq.br/4768904697900863
    In this work, we develop a method for locating partial discharges (PDs), in power transformers, based on GPS (Global Positioning System) algorithm. For analyzing the structure, we implement a software in which the di erential equations that describe the propagation of acoustic waves are solved numerically by the Acoustic Finite-Di erence Time-Domain (AFDTD) method. The AFDTD computational domain is truncated by the CPML technique (Convolutional Perfectly Matched Layer). The obtained results are compared to estimates produced using electromagnetic waves generated by PDs.
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    Um método fuzzy para programação de inspeções em transformadores baseado na análise de gases combustíveis e parâmetros físico-químicos do óleo isolante
    (Universidade Federal do Pará, 2014-10-24) PANTOJA, Márcia Priscila Furtado; OLIVEIRA, Terezinha Ferreira de; http://lattes.cnpq.br/6230804143692945; SILVEIRA, Antônio Morais da; http://lattes.cnpq.br/7549503749842625
    Power transformers using oil for insulation internal parts need periodic maintenance of a program aimed at detecting possible failures, such as deterioration of the winding insulation cellulose, short circuit between turns, gases dissolved in the oil due to its degeneration etc. Typically, preventive maintenance programs are used by companies for generation, transmission and distribution of electricity for avoiding these failures may result in removal of equipment from the electrical system, a situation that involves large financial losses, either by decreased billing at payment of penalties to the regulatory agency, as well as reduced system reliability. To avoid these types of losses, this paper presents a proposed solution using fuzzy approach, to assist the process of inspections programming in high power transformers (500kv), through the analysis of gases dissolved in insulating oil, obtained by the technique gas chromatography and physico-chemical analysis of the oil. We attempted to produce a solution that combines the results of traditional methods already established in the literature, with additional situations originating from the physico-chemical analysis of the oil and knowledge of experts in order to increase the effectiveness of such equipment inspection procedure. With this, any Electric Power System - SEP - that performs diagnostics on transformers by NBR 7274, tends to get a more accurate diagnosis, due to the association of physical-chemical analysis of the insulating oil with gas chromatography and knowledge tacit from specialists, enabling us to expand the base of original rules of that technical standard. All tests and the database used were from a laboratory of Chemistry of various electrical substations of an power company located in Barcarena - Pará - Brazil.
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