Dielectric Spectrum and Insulation State Analysis of Ultra-High Voltage Converter Transformer Bushing Based on Small Sample Digital Twin Model

This article introduces design and manufacturing method of 10kV epoxy resin impregnated dry-type bushing, and builds experimental platform for measuring dielectric properties using IDAX300. Dielectric spectra of manufactured epoxy resin impregnated dry bushing is measured at different temperatures, and experimental data were compared and analyzed. From the beginning, conduct dielectric spectrum experiments in frequency range of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{-3}-10^{3}\ \text{Hz}$</tex> with the temperature interval of 5°C until 90°C. Measure the dielectric spectrum of the epoxy resin samples, and conducting the dielectric spectrum experiments in frequency range of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10^{-1} \sim 10^{6}\ \text{Hz}$</tex>, with temperature interval of 5°C until 200°C.when the electric field strength is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\operatorname{low}\left(\leqslant 20 \text{kV} \cdot \text{mm}^{-1}\right)$</tex>, no injection of the space charge is observed inside the sample, only the space charge peak generated by the polarization appears on the metal electrode.