Simulation Analysis of Metallic Particles Movement in Typical Structure of Oil-immersed Power Transformer

Abstract

The insulation performance of oil-immersed power transformers is closely involved with the movement of metal particle impurities, and the movement characteristics of metal particles are not only influenced by the electric field, but also by the oil flow. In this paper, a solid-liquid two-phase flow simulation model was constructed, and the effect of electric field on the motion of metal particles was considered. Firstly, the validity of the simulation model was verified by using the experimentally observed motion of metal particles in the horizontal oil channel between parallel flat plate electrodes, based on which the motion of metal particles in the typical oil channels of a 500kV power transformer was studied. It was found that when the metal particles passed through the oil flow inlet, the number of metal particles settling increased with the increase of particle size. All the metal particles with 1mm particle size sank in the oil flow inlet during the oil migration process, it was almost impossible to enter the low, medium and high voltage winding parts. Through the middle or upper end of the high voltage winding, the smaller particles (50μm, 150μm) would easily migrate with the oil flow and move faster; the larger particles (500μm) would move slower or be more easily deposited. This research holds significant practical implications in the engineering study of metal particle motion distribution within transformers.