Pressure Influence Analysis of Dissolved Gas in Insulation Oil Based on Molecular Simulation and Experimental Comparsion

The sealing performance of transformer has important influence on its safe operation. However, sealing of the equipment is related to the pressure that applied. In this paper, gas content test of mineral oil under different pressures were conducted to simulate the situation under different sealing degree, and the two-parameter Weibull distribution was used to analysis the data. Composite model of mineral oil and air have been built and balanced under different pressures. The amount of gas molecules in mineral oil and the interaction between gas molecules and mineral oil were calculated. The test results show that the gas content of mineral oil increases gradually with the increase of pressure. When the pressure increased from 6.3kPa to 101.3kPa, the gas content in mineral oil with a probability of 63.2 % increased from 4.26 % to 8.99 %. When the pressure increased by 16.08 times, the gas content in mineral oil increased by 2.11 times. The repeatability of the three measurements was good. The simulation results show that with the increase of pressure, the interaction energy between mineral oil and gas molecules increases gradually, and the number of gas molecules entering mineral oil increases. When the pressure increases from 10.1kPa to 1013kPa, the interaction energy between mineral oil and gas molecules increases from 68.61 kcal/mol to 104.98 kcal/mol. The number of gas molecules entering the mineral oil increased from 110 to 161. The experimental results are in good agreement with the simulation results.