Teses em Engenharia Elétrica (Doutorado) - PPGEE/ITEC
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2317
O Doutorado Acadêmico inicio-se em 1998 e pertence ao Programa de Pós-Graduação em Engenharia Elétrica (PPGEE) do Instituto de Tecnologia (ITEC) da Universidade Federal do Pará (UFPA).
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Item Acesso aberto (Open Access) Avaliação da segurança de sistemas de potência para múltiplas contingências usando árvore de decisão multicaminhos(Universidade Federal do Pará, 2017-09-15) OLIVEIRA, Werbeston Douglas de; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; VIEIRA, João Paulo Abreu; http://lattes.cnpq.br/8188999223769913The search for effective ways to promote the secure operation of power systems and to increase its understanding by operators has encouraged continuous research for new techniques and methods that can help in this task. In this paper, it is proposed an approach to assess power system operation security for multiple contingencies using a multiway decision tree (MDT). The MDT differs from other decision tree techniques for establishing, in the training step, one value of the categorical attributes by branch. This approach proposes the use of topologies (contingencies) as categorical attributes. In this way, it improves interpretability regarding the power system operational state, as the operator can see clearly the critical variables for each topology, such that the MDT rules can be used in aiding the decision-making. This proposal was used for security assessment of two test systems, the IEEE 39-bus system and the Northern part of the Brazilian Interconnected Power System (BIPS), and BIPS was tested with real data from one day operation. The proposed MDT-based technique demonstrated superior performance, with a set of simple and clear rules. It was also performed a comparison of the obtained results with other techniques based on DT and it turned out that MDT has resulted in a simpler procedure for power system security classification with good accuracy.Item 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/1958791286192330Conventionally 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.