Effect of Charge Accumulation and Discharge in Filling Paste of Insulation in HVDC Systems

作者：Xinwei Li, Jinyu Wang, Jianbin Fan, Lingqi Tan, Ma Kai, Ma Yanjun · 年份：2025 · DOI：10.1109/epee67527.2025.11428777 · 研究领域：High voltage insulation and dielectric phenomena、Power Transformer Diagnostics and Insulation、Thermal Analysis in Power Transmission

Charge accumulation and electric field enhancement are critical factors in evaluating the performance of DC insulators, particularly because the actual operating electric stresses remain well below discharge thresholds. This study investigates charge accumulation under DC electric fields and its influence on polarization and breakdown characteristics. The results indicate that both the charge accumulation rate and charge density are significantly higher in filling paste containing bubbles compared with bubble-free paste, which leads to a pronounced local electric field enhancement within the bubbles. Consequently, the breakdown strength of bubble-containing samples is markedly lower than that of pure paste. Overall, the presence of bubbles, especially subvisible ones with diameters of$\mathbf{1 0}^{\mathbf{4}} \mathbf{~ m}$or smaller, poses a serious threat to the insulation reliability of the filling paste.