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A existência do regime de neutro em subestações de distribuição de energia elétrica
é essencial para o bom funcionamento de toda a rede. Existe um vasto leque de opções no
que diz respeito aos regimes de neutro. Cada opção tem as suas vantagens e
desvantagens, e cabe às empresas do setor elétrico a escolha do regime de neutro mais
adequado em função das caraterísticas da rede. A escolha do regime de neutro tem
influência direta no desempenho global de toda a rede de média tensão.
O principal objetivo desta dissertação é o estudo e a análise das vantagens e
inconvenientes dos vários regimes de neutro: neutro isolado, neutro impedante, ligado
diretamente à terra, neutro ressonante, analisando as suas vantagens e inconvenientes. É
feito um estudo aprofundado do regime de neutro ressonante, também designado por
regime de neutro com a Bobine de Petersen. Este trabalho descreve, ainda, de forma
sucinta a situação de Portugal relativamente aos regimes de neutro que utiliza e a sua
perspetiva futura.
Por fim é apresentado um caso de estudo, que diz respeito a uma rede de média
tensão (30 kV) alimentada pela subestação de Serpa. Foram estudados os regimes de
neutro como a bobine de Petersen, reatância de neutro e neutro isolado. Foi também
estudada a influência na ocorrência de um defeito fase-terra e a influência na ocorrência de
defeitos francos e resistivos em vários pontos da rede.
The existence of the neutral earthing in distribution substations of electricity is essential to the proper functioning of the entire network. There is a wide range of options in neutral earthing. Each option has its advantages and disadvantages and it is up to the electric companies to choose the most appropriate system depending on the characteristics of the network. The choice of the neutral earthing has a direct influence on the overall performance of the entire medium voltage network. The main objective of this dissertation is the study and analysis of the advantages and disadvantages of the various neutral earthing: isolated neutral, neutral impedant, connected directly to earth, resonant grounding, analyzing their advantages and drawbacks. A thorough study of the resonant grounding, also called the neutral earthing with the Petersen Coil, was made. This study also briefly describes the situation of neutral earthing and its future perspective in Portugal. We present the study of a network of medium voltage (30 kV) fed by Serpas’ substation. We studied neutral earthing, as Petersen coil, reactor and neutral ungrounded. The influence on the occurrence of a phase to ground fault, the frank and resistive defects at several points of the network were also studied.
The existence of the neutral earthing in distribution substations of electricity is essential to the proper functioning of the entire network. There is a wide range of options in neutral earthing. Each option has its advantages and disadvantages and it is up to the electric companies to choose the most appropriate system depending on the characteristics of the network. The choice of the neutral earthing has a direct influence on the overall performance of the entire medium voltage network. The main objective of this dissertation is the study and analysis of the advantages and disadvantages of the various neutral earthing: isolated neutral, neutral impedant, connected directly to earth, resonant grounding, analyzing their advantages and drawbacks. A thorough study of the resonant grounding, also called the neutral earthing with the Petersen Coil, was made. This study also briefly describes the situation of neutral earthing and its future perspective in Portugal. We present the study of a network of medium voltage (30 kV) fed by Serpas’ substation. We studied neutral earthing, as Petersen coil, reactor and neutral ungrounded. The influence on the occurrence of a phase to ground fault, the frank and resistive defects at several points of the network were also studied.
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Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto