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Análise da influência das sobrecorrentes transitórias de excitação na proteção diferencial de transformadores
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Abstract(s)
Os transformadores são elementos da rede que permitem alterar o nível de tensão, permitindo o transporte de energia elétrica a longas distâncias, a menores custos, o que os torna essenciais em sistemas de produção, transporte e distribuição de energia. Devido à sua importância nos sistemas de energia elétrica é essencial garantir o correto funcionamento dos seus dispositivos de proteção, por forma a isolar os defeitos ainda numa fase inicial, e assim evitar avarias catastróficas, minimizando os danos e reduzindo o período e custos de indisponibilidade. O aperfeiçoamento dos sistemas de proteção dos transformadores revela-se assim de extrema relevância, por forma a aumentar a fiabilidade global dos sistemas de produção, transmissão e distribuição de energia elétrica.
O relé diferencial pode assumir a sobrecorrente transitória de excitação como uma corrente de defeito, removendo indevidamente o transformador de serviço. Para melhorar e desenvolver novos algoritmos de proteção é necessário caracterizar com rigor as condições onde as sobrecorrentes transitórias de excitação possuam valores reduzidos de segundo harmónico ou este seja gerado por um defeito interno. O objetivo principal deste trabalho consiste nessa caracterização. Para o efeito será utilizada a ferramenta de simulação Simulink/Matlab e correspondente validação experimental.
The transformers are the elements in the power grid that allow to adjust the voltage level, enabling power transmission at long distance less expensive, which makes them essential in power production, transmission and distribution systems. Due to their importance in power systems it is fundamental to ensure the correct operation of their protection devices, to isolate at an early stage any type of fault, thus avoiding catastrophic failures, minimizing damage, and reducing unavailability and costs. Transformers protection systems improvements are of extreme importance to increase power systems reliability. Differential relays may assume an inrush current as a fault current, removing incorrectly the transformer out of service. To improve and develop new protection algorithms it is necessary to characterize accurately the conditions were the inrush current has low second harmonic level, or they are created by internal faults. The main objective of this work is characterizing those conditions. For this purpose, experimental and simulated results were obtained, using a laboratory test setup and MATLAB/Simulink computational models, respectively.
The transformers are the elements in the power grid that allow to adjust the voltage level, enabling power transmission at long distance less expensive, which makes them essential in power production, transmission and distribution systems. Due to their importance in power systems it is fundamental to ensure the correct operation of their protection devices, to isolate at an early stage any type of fault, thus avoiding catastrophic failures, minimizing damage, and reducing unavailability and costs. Transformers protection systems improvements are of extreme importance to increase power systems reliability. Differential relays may assume an inrush current as a fault current, removing incorrectly the transformer out of service. To improve and develop new protection algorithms it is necessary to characterize accurately the conditions were the inrush current has low second harmonic level, or they are created by internal faults. The main objective of this work is characterizing those conditions. For this purpose, experimental and simulated results were obtained, using a laboratory test setup and MATLAB/Simulink computational models, respectively.
Description
Keywords
Bloqueio harmónico Defeitos internos e externos Sobrecorrentes transitórias de excitação e transformadores