Simulation Study on Acetylene Gas Diffusion Process in Large Transformers

Abstract

To discover the influence of the diffusion process of acetylene gas in large oil filled power transformers on the dissolved gases analysis results, the diffusion process of acetylene gas over long distances and the influencing factors have been investigated by simulation. In this paper, based on the convection-diffusion equation of acetylene gas in oil, a one-dimensional model for the diffusion of acetylene gas in a 10 m long oil duct is established and numerically solved by the backward difference method. The simulation found that in right-angle coordinates, the concentration of acetylene gas in the oil is uniformly diffused outward, and the arrival time of the gas is related to the flow rate; in polar coordinates, the acetylene gas is mainly concentrated in the area near the defects and the tank wall, and the distribution of the gas content is extremely inhomogeneous, and the homogeneous state can not be reached for a long time. The results show that the simulation of gas production from local defects in large transformers is closer to reality by using polar coordinate form and boundary flux conditions; because the diffusion coefficient is very small in magnitude, the slow flow of transformer oil leads to the predominant convective transfer of acetylene gas.