Navegando por Assunto "High voltage"
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Item Acesso aberto (Open Access) Adequação do laboratório de alta tensão da UFPA - LEAT aos requisitos gerais para a competência de laboratórios de ensaio e calibração da norma ABNT NBR ISO/IEC 17025(Universidade Federal do Pará, 2022-02-24) BRASIL, Alexandre de Souza; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447Phenomena that cause electrical imbalances in power systems occur constantly, which generates the need to study them in order to allow the development of electrical networks and equipment that behave more reliably and robustly in the face of such disturbances. These studies are generally carried out in specialized High Voltage and High Power laboratories. Over the years, the market started to demand that these studies also provide results that comply with quality standards certified by official bodies. In this sense, this dissertation aims to propose the necessary adaptation of the High and Extra High Voltage Laboratory of the Federal University of Pará (LEAT) to the requirements for the competence of testing and calibration laboratories defined by the ABNT NBR ISO/IEC 17025 standard, with a focus on development and implementation a Quality Management System; creation of operational procedures and safety guidelines; establishment of a calibration program for laboratory equipment; and identification of motivations, advantages and impacts related to the implementation of the requirements of that standard, as well as the difficulties and solutions found. For this, first, a literary survey was carried out that sought to know the national panorama of higher education institutions with accredited laboratories under the referred standard. Then, the process of implementing the requirements of the standard began, which was based on the methodology adapted from Grochau (2011). Finally, the lived experience allowed us to observe that the adaptation to the standard requirements in laboratories linked to public institutions, although complex at first, is fully capable of providing several benefits and advantages, as long as the peculiarities of this type of institution are respected, such as: bureaucracy; resource limitation; training of the personnel involved and; reconciling research and teaching activities with services provision.Item Acesso aberto (Open Access) Aplicação de método de reconstrução de sinais baseado em decomposição variacional de modos no processamento de sinais de descargas parciais(Universidade Federal do Pará, 2024-09-23) ALMEIDA, Vanilze Vaz Monteiro de; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447High-voltage equipment in electrical systems is subject to electrical insulation degradation, which promotes the evolution of partial discharge activity (PDs), a key factor in operational failures of these assets, resulting in significant losses. Therefore, the analysis of PD signals for accurate representation of operational conditions is essential, as it aids in making assertive decisions in predictive maintenance of equipment, as well as understanding their impacts. The procedure for acquiring PDs involves measurements using invasive or non-invasive devices, which show the occurrence of this phenomenon under field or laboratory operating conditions. However, this acquisition is subject to interference, leading to PD signals embedded in noise, which may arise from the electromagnetic nature of the equipment used or from external sources. This highlights the need to implement noise reduction and signal reconstruction techniques that ensure good representation of PDs, allowing for precise analysis by minimizing the loss of signal characteristics for further studies. Thus, in this work, a study was conducted on four noise reduction techniques for PD signals: Variational Mode Decomposition (VMD), Adaptive Filtering with Least Mean Squares algorithm (LMS), Wavelet Transform with Hard Thresholding (HTWT), and Wavelet Transform with Soft Thresholding (STWT), for reconstructing real PD signals obtained from measurements with High-Frequency Current Transformer (HFCT). The results from the signal filtering process were evaluated using metrics such as Root Mean Square Error (RMSE), Signal-to-Noise Ratio (SNR), and Correlation Coefficient (CC), demonstrating the importance of filtering methodology with the incorporation of VMD and the variation of parameters and filtering sequences established.Item Acesso aberto (Open Access) Simulação de ensaio de impulso atmosférico em transformadores de baixa indutância utilizando circuito Glaninger e programa ATP para o laboratório de extra alta tensão da UFPA(Universidade Federal do Pará, 2017-03-31) BARRADAS, Raphael Pablo de Souza; NUNES, Marcus Vinícius Alves; http://lattes.cnpq.br/9533143193581447One of the major difficulties observed in high voltage laboratories is the adjustment of the atmospheric (voltage) impulse waveform during the tests. This difficulty is due to the fact that, most of the time, the capacitance of the object under test is not known, and it is not possible to make an exact calculation of the parameters to be used in the impulse generator. In the case of transformer tests, these difficulties increase because, in addition to the inherent capacitance of their insulation, there is also an inductance contribution to the test circuit from their windings. This fact makes it even more difficult to obtain a normalized waveform according to the NBR IEC 60060-1 standard. The present Master's Dissertation presents and evaluates methodologies that allow the performance of standardized voltage impulse tests in transformers with low inductances, common in electric power distribution systems. It will be highlighted in the results obtained with the insertion of a Glaninger circuit, compared to the methodology based on the increase of the total parallel resistance of the circuit under test. The computational simulations are performed in the ATP (Alternative Trasient Program) program, using rated values of physical parameters of the high voltage equipment of the Extra High Voltage Laboratory of the Federal University of Pará (LEAT). Through an initial modeling of the voltage impulse generator of the LEAT in the ATP program, the simulated results are validated by performing a real test in the LEAT. After validation, a test simulation in a low inductance distribution transformer is performed in order to present the deformations in the waveform of the impulse that occur, due to the low inductances of the transformer windings. Through the introduction of a suitably adapted Glaninger circuit, the solution to the above problem is presented, permitting tests on transformers with low inductances to be performed according to criteria established by current standards.