Electrical Characterization and Quantum Dynamics Simulation of Oil-Immersed Pressboard Modified by SiO₂ Under Electrothermal Accelerated Aging Conditions

The cellulose insulation pressboard is responsible for the main insulation task of the oil-immersed transformers. The prolonged exposure to the electrical and thermal environment inside the transformer results in a decline in the electrical performance of the oil-immersed pressboard. Currently, there is significant research interest in utilizing nanomodification technologies to enhance the electrical performance of cellulose insulation. This article investigates the impact of nano-SiO2 modification on the electrical properties of the cellulose insulation pressboard in the electric and thermal fields. The unmodified and modified cellulose molecular models are established. The cellulose molecule model to quantum dynamics simulations is subjected. A comparison of the energy gap, electrostatic potential, Raman spectroscopy, and infrared spectroscopy for unmodified and modified cellulose molecular models is obtained. A temperature-controlled measurement platform for the distribution of space charges is established under direct current (dc) voltage. The space charge buildup and dissipation properties of unmodified and modified cellulose insulation pressboards are compared to evaluate the impact of nano-SiO2 particles. The results show that the coupling effect of electric and thermal fields increases the energy gap of the cellulose molecular model modified by nano-SiO2, forms more hydrogen bonds, enhances system stability, reduces polarization and dipole moment changes of the molecules, and improves dielectric performance. Compared with an unmodified pressboard, a modified pressboard has a lower maximum field distortion rate, a faster space charge dissipation rate, and lower carrier mobility. Adding nano-SiO2 particles to cellulose insulation pressboard makes it work better electrically when it is in an electric thermal coupling field.