Simulation Study on the Motion Characteristics and Influencing Factors of Fiber Impurity Particles in Oil Flow in a Typical Distributed Electric Field

There have been many studies on the motion and aggregation characteristics of fiber impurities in insulation oil under static conditions. However, there are few studies on the motion characteristics of fiber impurities in insulation oil under flow conditions. In large power transformers, insulation oil is constantly in a state of flow. As a result, the motion characteristics of fiber impurities suspended in the insulation oil are even more complex due to the effects of oil flow. This study constructed a multiphysics field model for single-particle fibrous impurities in solid–liquid two-phase flow and systematically analyzed its motion characteristics. The study shows that the collision frequency between fiber impurity particles and electrodes with the same effective area is negatively correlated with the degree of electric field distortion. The maximum particle velocity and collision frequency of fibrous impurities in both uniform and slightly nonuniform electric fields show an almost linear relationship with the particle size radius. In addition, the slope of the relationship decreases gradually with an increase in oil flow rate. With the increase of particle size, under the same flow velocity, an increase in the maximum velocity of the fibrous particles and the number of collisions with the electrodes, thereby increasing the probability of fibrous impurities transferring charge between the electrodes. Compared to the motion characteristics of fibrous impurity particles under static conditions, oil flow mainly affects the collision frequency between fibrous impurity particles and electrodes, reducing the probability of particle transfer.