Effective analysis of time-domain dielectric response for reliable diagnosis of power transformer insulation using statistical parameter evaluated from time-varying model

摘要

Various types of insulation models with time-invariant parameters are available in the literature. Depending on the aging sensitive performance parameters to be evaluated, different models need to be employed (e.g. XY model for oil and paper-conductivity, conventional Debye model (CDM) for paper-moisture and tan delta). While the XY model cannot be used for estimating paper-moisture directly, analysis based on CDM parameter becomes dependent on its branch parameters, which are non-unique. These factors lead to either incomplete or ambiguous insulation diagnosis. These problems are resolved using the proposed new insulation model containing unique time-varying branch parameters. Another major advantage of the proposed model is that it can be used to evaluate a host of performance parameters (like paper-conductivity, oil and paper-moisture, dielectric loss) thus giving a complete picture of the insulation concerned. The application of the proposed model is also tested on data collected from several real-life power transformers.