Browsing by Author "Baracho, Francisco Ricardo Abrantes Couy"

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    A new admittance approach applicable to the coordination between the loss-of-excitation protection and the underexcitation limiter.
    (2020) Baracho, Francisco Ricardo Abrantes Couy; Coelho, Aurélio Luiz Magalhães; Pereira Filho, Clever Sebastião; Damião, Laerty João dos Santos; Zvietcovich, Wilingthon Guerra
    The performance of salient-pole synchronous generators protection is of great importance for the stability of power systems, as they are present in large hydropower plants, subject to various abnormal operating conditions such as threephase or two-phase faults, electromechanical disturbances and lossof-excitation. In this context, this work proposes a testing philosophy of salient-pole synchronous generators, in order to define more accurately the setting of the protections and controls of this asset. Thus, in the developed methodology, the admittance plan (G-B) proves applicable to analyze the coordination between the loss-ofexcitation protection and the underexcitation limiter, as an alternative to the power (P-Q) and impedance (R-X) planes, normally employed in literature. In modeling the problem, real data for both the hydrogenerators and the electrical network are used. The simulations were performed in a hardware-in-the loop scheme integrated by a Real Time Digital Simulator and a physical relay. Thus, analyzes are made for situations of stable power swing and partial and total loss-of-excitation. The results are useful to prove, through the monitoring of relevant variables of the hydrogenerators, the feasibility and accuracy of the G-B plane in the coordination between the protection and the control of the synchronous machine
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    Remoção da interferência de 60 hz no sinal de ECG usando filtro notch digital.
    (2019) Barbosa, Gustavo Vinícius Duarte; Baracho, Francisco Ricardo Abrantes Couy; Santos, José Ronaldo Tavares; Damião, Laerty João dos Santos
    A interferência de 60 Hz AC pode ser um problema em qualquer situação de medição de biopotencial. A fonte dessa interferência é o potencial AC da rede de alimentação de energia elétrica que está inevitavelmente presente em qualquer situação clínica, ou para iluminação do ambiente ou como fonte de suprimento dos equipamentos de medição. A interferência causada pela rede elétrica, em 60 Hz, pode ser difícil de detectar visualmente em sinais tendo formas de onda não-regulares, como o EEG ou o EMG. Não obstante, a interferência é facilmente visível quando presente em sinais com formas de onda bem definidas, como é o caso do sinal de ECG (Eletrocardiograma). Em todo caso, o espectro de potência do sinal deve fornecer uma indicação clara da presença da interferência da rede como um impulso em 60 Hz. Os harmônicos, caso presentes, aparecem como impulsos adicionais em múltiplos inteiros da frequência fundamental. Neste trabalho é demonstrada uma técnica de filtragem, empregando um filtro “Notch” digital, o qual remove o artefato de 60 Hz do sinal de ECG, aumentando a confiabilidade do diagnóstico clínico a partir da interpretação do mesmo.
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    Técnica de localização de faltas em linhas de transmissão empregando o método dos mínimos quadrados.
    (2019) Barbosa, Gustavo Vinícius Duarte; Pereira Filho, Clever Sebastião; Baracho, Francisco Ricardo Abrantes Couy; Santos, José Ronaldo Tavares; Damião, Laerty João dos Santos
    A investigação de diferentes tipos de faltas em linhas de transmissão é uma tarefa complexa e de extrema importância para o Sistema Elétrico de Potência (SEP). A modelagem da linha de transmissão deve ser estabelecida da forma mais rigorosa possível, visando à precisão das distâncias de faltas simuladas a partir dos modelos levantados. Neste trabalho será modelada uma linha de transmissão em circuito simples usando o programa de cálculo de transitórios eletromagnéticos ATPDraw® e, posteriormente, o algoritmo de localização de falta baseado no emprego do método dos mínimos quadrados será implementado no MATLAB®. O desempenho do método será discutido em termos de precisão e robustez dos resultados.
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    A test-bed for researching the interactions of underexcitation and overexcitation limiters of synchronous generators with protection functions.
    (2019) Coelho, Aurélio Luiz Magalhães; Silveira, Paulo Márcio da; Baracho, Francisco Ricardo Abrantes Couy
    A test-bed implemented in a real-time digital simulation environment is presented in this article to perform coordination studies between protection functions and excitation limiters of automatic voltage regulators of synchronous generators. A hardware-in-the-loop simulation is implemented in laboratory to test and evaluate several protection schemes during underexcited and overexcited events. The interactions among the underexcitation and overexcitation limiters (UEL and OEL) with these protection functions are investigated, and the best settings for their coordination are proposed. This article increases the scope of [1] and [2] by including the interactions among the protection functions ANSI 24 (V/Hz), ANSI 59 (overvoltage), and ANSI 81 (underfrequency and overfrequency) with the OEL, and the interactions among the protection functions ANSI 21 (distance) and ANSI 27 (undervoltage) with the UEL in addition to the coordination between the protection function ANSI 40 (loss of excitation) and the UEL. Thus, the appropriate settings for these protection and controls are proposed for the excitation system developed. The main results are presented and discussed.
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    The decision support in electricity generation : a model of integrated parameters and indicators.
    (2015) Baracho, Renata Maria Abrantes; Bonatti, Rogério Amaral; Baracho, Francisco Ricardo Abrantes Couy; Pessanha, Christiano; Rezende, Marina M. Starling; Silva, Cláudio Homero Ferreira
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    A theoretical and practical approach for underexcitation protection and control studies of hydrogenerators in a real-time environment.
    (2018) Baracho, Francisco Ricardo Abrantes Couy; Pereira Filho, Clever Sebastião; Coelho, Aurélio Luiz Magalhães; Silveira, Paulo Márcio da
    –The installation and settings of protection devices and excitation control systems require experience since a failure can cause damage to the synchronous generator and negative impact on the power grid. A test bed implemented in a real-time digital simulator is presented in this paper as an alternative for the training and learning process that involves the knowledge of an effective coordination between such protection and control systems of synchronous generators. A complete generation system is implemented in a real-time digital simulator, including an excitation system model with its limiters. These limiters are coordinated with the protection functions implemented in a physical relay. The contributions of this work are: the demonstration of the importance of this type of study (i.e., real time simulations results through hardware-in-the-loop tests); the consolidation of the impedance (R-X) and admittance (G-B) planes as the more appropriate ones to analyze the coordination between the ANSI 40 function and the underexcitation limiter; and the presentation of a study focused on hydrogenerators (including novel settings for the ANSI 40 protection).