Parameter estimation of dielectric response circuit using improved mathematical model

Return voltage method can assess water content in transformer pressboard by dominant time constant. However, the data of return voltage method (RVM) takes for a long measuring time. The parameters of dielectric response based on extended Debye circuit model can reflect oil-paper insulation state. To shortcut measuring time, therefore, it is necessary to estimate equivalent circuit parameter and calculate return voltage characteristic quantity. This paper established improved mathematical model using return voltage peak, peak time and initial slope characteristics to solve dielectric response equivalent circuit parameters. And then improved bacteria foraging algorithm is used for solving the problem. The improved mathematical model can decrease sampling data of return voltage. The result shows that the dominant time constant calculated and measured return voltage curve have good consistency, which can accurately diagnose the transformer oil-paper insulation status. It illustrates that the improved method proposed in this paper is feasible and effective.