Influencing factors and uncertainty analysis for Kerr electro-optic effect based electric field measurements in transformer oil under impulse voltage

Abstract

Abstract The design of insulating structures for transformers under impulse voltage relies predominantly on simulation software due to the absence of experimental validation. This underscores the pressing need for comprehensive research into the spatial electric field and charge properties of oil-paper/pressboard insulation systems. In response to this imperative, a suite of specialized instruments leveraging the Kerr electro-optic effect to meticulously measure the spatial electric field within oil-pressboard structures under impulse voltage was established. As the precision of measurements hinges upon a multitude of influencing factors, this study embarks on a multifaceted examination, centering its focus on four pivotal dimensions: incident laser beam angle, electrical noise, temperature and non-ideal optical elements. A quantitative calculation method for electric field measurement errors was presented, and on the basis of which, suppression methods are proposed for the error sources having the largest impacts on the experimental results. Finally, the overall measurement uncertainty of the device is systematically evaluated.