Navegando por Assunto "Capacitance"

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Acesso aberto (Open Access)
Metodologia baseada em modelo teórico para avaliação do estado operativo de linha de transmissão
(Universidade Federal do Pará, 2015-05-15) NEGRÃO, Martin Max Luis de Castro; BARREIROS, José Augusto Lima; http://lattes.cnpq.br/1246564618922453; VIEIRA JÚNIOR, Petrônio; http://lattes.cnpq.br/1958791286192330
Conventionally monitoring operating conditions of a power transmission line is accomplished by periodic inspections along this line. This monitoring allows corrective maintenance by finding faults during the inspection. But in more efficient maintenance, predictive techniques that are characterized by real-time monitoring should be employed. The predictive techniques verify the operating status using normal function models for fault detection and fault models for the diagnosis to be employed in PDI (Fault Detection and Isolation). So, we developed a mathematical model appropriate for application to predictive maintenance of transmission line segments at low cost, without the need for sensors distributed along the line. This model allows the use of the methodology for detecting faults (PDI) by monitoring the leaka ge current of transmission lines. The use of the model also allows obtaining a new indicator of the condition of normal and abnormal functioning of a transmission line, which is the capacitance of harmonic frequencies. The model was validated through measurements obtained on a section of transmission line, by means of an artificial neural network.
Acesso aberto (Open Access)
Modelo matemático de linhas de transmissão, contemplando influências ambientais, para o trecho Guamá-Utinga, localizado em Belém, pertencente à Eletronorte
(Universidade Federal do Pará, 2009-03-30) NEGRÃO, Martin Max Luis de Castro; OLIVEIRA, Roberto Célio Limão de; http://lattes.cnpq.br/4497607460894318
Theoretically, the prediction of failure in the chain of insulators can be found by checking the behavior, of the harmonic current through the insulators, called leakage current. This is because the capacitance of a chain of insulators allows the passage of components of higher order harmonics of the current line, however the design and planning of transmission lines, only take into account the size and geometry of the line, forgetting or ignoring the effects environment in a line of transmission, the omission of such effects can confuse the diagnosis of failure in the system of isolation of the line, so it was necessary to develop a methodology for determining the values of electrical parameters, electrical resistance and capacitance as a function of environmental variables as: temperature, solar radiation, relative humidity, wind speed and wind direction, particularly the determination of the behavior of capacitance as a function of environmental variables was so innovative and experimental, in order to obtain a mathematical model of line transmission of more realistic and dynamic, that can more precisely identify the electrical parameters under the influence of environmental variables, such work is developed this model, which will be fed with real environmental and electrical data, it made the study of the harmonic decomposition of current leakage, and the comparison with results of other existing models, are still held, virtual simulations of failures, which bought the efficiency and limitations of the model, and suggest a way of monitoring in real time and low cost.