Impacto de microrredes sobre o sistema de proteção de redes de distribuição
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2019-11-04
Autores
Gifalli, André
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Universidade Estadual Paulista (Unesp)
Resumo
A crescente demanda por energia elétrica, combinada com questões ambientais e financeiras, vem promovendo a integração de unidades geradoras distribuídas nas redes de distribuição. Essa configuração topológica, construída próxima aos consumidores, consiste em um conceito chamado de microgrid, desenvolvido nos últimos anos. Esse modelo é caracterizado por um conjunto de pequenas unidades geradoras, cargas e dispositivos de armazenamento de energia, capazes de operar em modo paralelo ou isolado, em relação à rede existente. Vários estudos apontam que as microrredes influenciam o planejamento, operação e manutenção da rede de distribuição elétrica, principalmente porque as microrredes funcionam em um fluxo de energia bidirecional em vez do modo unidirecional convencional. Essa topologia de rede pode influenciar significativamente o perfil de tensão, estabilidade, qualidade de energia e comportamento de proteção do sistema elétrico. Em relação ao esquema de proteção, esses sistemas podem interferir na coordenação e seletividade dos equipamentos que constituem a rede. Nesse sentido, o objetivo desta dissertação é analisar o impacto da contribuição da corrente de curto-circuito das conexões de microrrede no sistema de proteção de sobrecorrente nas redes de distribuição convencionais. A análise é desenvolvida modelando uma rede de distribuição IEEE de 34 barras. O software OpenDss é usado em conjunto com um aplicativo Python desenvolvido para avaliar os impactos na coordenação e seletividade do equipamento de proteção contra sobrecorrente. Além disso, um estudo bibliométrico foi desenvolvido para analisar algumas soluções sugeridas. Os resultados mostraram que a filosofia de proteção, atualmente adotada para redes de distribuição, não é capaz de fornecer todas as respostas para os problemas relacionados à inserção de unidades de geração distribuída. O motivo é que a contribuição da corrente de curto-circuito interfere diretamente na coordenação entre os dispositivos de proteção já existentes. Até o momento, os regulamentos existentes afirmam que, no caso de um mal funcionamento do sistema, a unidade geradora distribuída deve ser imediatamente desconectada da rede. Assim, para uma implementação bem-sucedida de microrredes, novos esquemas de proteção devem ser desenvolvidos para manter as vantagens que as microrredes distribuídas trazem, sem efeitos colaterais
The growing demand for electricity, combined with environmental and financial issues, fostered the integration of distributed generating units into distribution networks. This topological configuration, build up nearby the consumers, consist of a concept called microgrid, which has been developed in recent years. This model is characterized by a set of small generating units, loads and energy store devices, capable of operating in a parallel or isolated mode, concerning the existing network. Several studies point out that the microgrids influence the planning, operation, and maintenance of the electrical distribution network, mainly because of microgrids woks with a bidirectional power flow rather than the conventional unidirectional mode. This network topology can significantly influence the voltage profile, stability, power quality, and electrical system protection behavior. Regarding the protection scheme, these systems can interfere with the coordination and selectivity of the equipment that constitutes the network. In this sense, the purpose of this dissertation is to analyze the impact of the short circuit current contribution from the micro-network connections in the overcurrent protection system in the conventional distribution networks. The analysis is developed by modeling an IEEE 34-bar distribution network. The OpenDss software is used in conjunction with a developed Python application to assess the impacts on coordination and selectivity of the overcurrent protection equipment. Also, a bibliometric study was developed to analyze some suggested solutions. The results have shown that the protection philosophy, currently adopted for distribution networks, is not able to provide all the answers to the issues related to the insertion of distributed generation units. The reason is that the contribution of short circuit current interferes directly with the coordination among the already existing protection devices. So far, the existing regulations state that, in the event of a system malfunction, the distributed generator unit must be immediately disconnected from the grid. Thus, for successful deployment of micro-networks, new protection schemes must be developed to maintain the advantages that distributed micro-networks bring without side effects
The growing demand for electricity, combined with environmental and financial issues, fostered the integration of distributed generating units into distribution networks. This topological configuration, build up nearby the consumers, consist of a concept called microgrid, which has been developed in recent years. This model is characterized by a set of small generating units, loads and energy store devices, capable of operating in a parallel or isolated mode, concerning the existing network. Several studies point out that the microgrids influence the planning, operation, and maintenance of the electrical distribution network, mainly because of microgrids woks with a bidirectional power flow rather than the conventional unidirectional mode. This network topology can significantly influence the voltage profile, stability, power quality, and electrical system protection behavior. Regarding the protection scheme, these systems can interfere with the coordination and selectivity of the equipment that constitutes the network. In this sense, the purpose of this dissertation is to analyze the impact of the short circuit current contribution from the micro-network connections in the overcurrent protection system in the conventional distribution networks. The analysis is developed by modeling an IEEE 34-bar distribution network. The OpenDss software is used in conjunction with a developed Python application to assess the impacts on coordination and selectivity of the overcurrent protection equipment. Also, a bibliometric study was developed to analyze some suggested solutions. The results have shown that the protection philosophy, currently adopted for distribution networks, is not able to provide all the answers to the issues related to the insertion of distributed generation units. The reason is that the contribution of short circuit current interferes directly with the coordination among the already existing protection devices. So far, the existing regulations state that, in the event of a system malfunction, the distributed generator unit must be immediately disconnected from the grid. Thus, for successful deployment of micro-networks, new protection schemes must be developed to maintain the advantages that distributed micro-networks bring without side effects
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Palavras-chave
Microrredes, Proteção, Rede de Distribuição, Microgrids, Protection, Distribution Network