Índice de saúde aprimorado para diagnóstico de transformadores de potência
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Data
2020-10-23
Autores
Silva, Daniella Gonzalez Tinois da
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Universidade Estadual Paulista (Unesp)
Resumo
O desligamento não planejado de transformadores de potência (TP) resulta em despesas significativas para as operadoras, tornando essencial o uso de técnicas de avaliação capazes de diagnosticar e estimar com eficiência as condições de operação reais de tais equipamentos. O diagnóstico eficiente permite a gestão da operação desta cadeia de ativos visando o equilíbrio ideal entre investimentos, custos de manutenção e desempenho na operação. Neste contexto, este trabalho apresenta uma metodologia de diagnóstico aprimorada para estimar o estado técnico/operacional dos transformadores de potência, comumente chamado de saúde do equipamento, baseada em dados de fácil aquisição e de baixo custo que podem ser obtidos sem a necessidade de interrupção na operação do TP. Especificamente, a metodologia emprega dados provenientes de análises de amostras de óleo, coletadas a partir de dispositivo externo ao equipamento e sem a necessidade de desligamento, e de sistemas de aquisição de grandezas elétricas disponíveis de forma remota, e, propõe a criação de um novo fator diagnóstico para identificar a condição da isolação sólida do transformador. O novo fator diagnóstico se baseia no histórico da curva média diária de carga do TP, permitindo a estimação e contabilização da degradação da isolação do TP “em serviço”. Além disso, o novo critério proposto, incorpora características que permitem que sejam incluídos os efeitos das distorções harmônicas na obtenção do índice de saúde. Assim, a metodologia de diagnóstico aprimorada tem a capacidade de estimar e atualizar o estado de saúde dos transformadores, em intervalos de tempo menores que os demandados pelas metodologias de diagnóstico do estado de saúde convencional, que dependem de resultados mais demorados, podendo representar uma ferramenta importante para o planejamento estratégico e otimização de recursos das empresas de energia elétrica. A eficácia da metodologia proposta foi avaliada considerando dados provenientes de uma população de 204 transformadores de potência instalados no Brasil em comparação direta com diagnósticos provenientes da metodologia do índice de saúde convencional, em que o índice de saúde aprimorado proposto se mostrou mais eficaz na observação da degradação do isolante sólido do enrolamento.
The unplanned shutdown of power transformers (TP) results in significant expenses for utilities, making it essential to use assessment techniques capable of efficiently diagnosing and estimating the actual operating conditions of such equipment. The efficient diagnosis allows the management of the operation of this chain of assets aiming at the ideal balance among investments, maintenance costs and performance in the operation. In this context, this work presents an improved diagnostic methodology to estimate the technical / operational status of the power transformers, commonly called equipment health, based on data of easy acquisition and low cost that can be obtained without the need to interrupt the TP operation. Specifically, the methodology uses data from analysis of oil samples, collected from a device external to the equipment and without the need for shutdown, and from remote electrical acquisition systems, and proposes the creation of a new diagnostic factor to identify the condition of the transformer's solid insulation. The new diagnostic factor is based on the history of the average daily load curve of the PT, allowing the estimation and accounting of the degradation of the PT insulation “in service”. In addition, the proposed new criterion incorporates characteristics that allow the effects of harmonic distortions to be included in obtaining the health index. Thus, the improved diagnostic methodology can estimate and update the health status of the transformers, in shorter intervals than those required by the conventional health status diagnostic methodologies, which depend on more time-consuming results, and may represent a tool important for the strategic planning and resource optimization of electric power companies. The effectiveness of the proposed methodology was evaluated considering data from a population of 204 power transformers installed in Brazil in direct comparison with diagnoses from the conventional health index methodology, in which the proposed improved health index was more effective in observing the degradation of the winding solid insulation.
The unplanned shutdown of power transformers (TP) results in significant expenses for utilities, making it essential to use assessment techniques capable of efficiently diagnosing and estimating the actual operating conditions of such equipment. The efficient diagnosis allows the management of the operation of this chain of assets aiming at the ideal balance among investments, maintenance costs and performance in the operation. In this context, this work presents an improved diagnostic methodology to estimate the technical / operational status of the power transformers, commonly called equipment health, based on data of easy acquisition and low cost that can be obtained without the need to interrupt the TP operation. Specifically, the methodology uses data from analysis of oil samples, collected from a device external to the equipment and without the need for shutdown, and from remote electrical acquisition systems, and proposes the creation of a new diagnostic factor to identify the condition of the transformer's solid insulation. The new diagnostic factor is based on the history of the average daily load curve of the PT, allowing the estimation and accounting of the degradation of the PT insulation “in service”. In addition, the proposed new criterion incorporates characteristics that allow the effects of harmonic distortions to be included in obtaining the health index. Thus, the improved diagnostic methodology can estimate and update the health status of the transformers, in shorter intervals than those required by the conventional health status diagnostic methodologies, which depend on more time-consuming results, and may represent a tool important for the strategic planning and resource optimization of electric power companies. The effectiveness of the proposed methodology was evaluated considering data from a population of 204 power transformers installed in Brazil in direct comparison with diagnoses from the conventional health index methodology, in which the proposed improved health index was more effective in observing the degradation of the winding solid insulation.
Descrição
Palavras-chave
Transformadores elétricos, Óleo de transformadores, Manutenção, Vida útil (Engenharia), Índice de saúde, Isolação sólida, Carregamento médio diário, Ferramenta de diagnóstico, Depreciação da vida útil, Power transformers, Health index, Solid insulation, Average daily load, Diagnostic tools, Depreciation of insulation