Simulation Research on Movement Characteristics of Fiber Impurity Particles in Flowing Insulating Oil
Zhang Guozhi1, Yan Weiyang1, Wang Kun1, Chen Kang1, Zhang Xiaoxing1,2
1. Hubei Engineering Research Center for Safety Monitoring of New Energy, Power Grid Equipment Hubei University of Technology Wuhan430000China; 2. Xiangyang Industrial Institute of Hubei University of Technology Xiangyang 441022 China
Abstract：Abstract During the production, transportation, installation, insulating oil filling, operation and maintenance of large power transformers, impurities with different properties and sizes will be mixed. Through the analysis of on-site insulating oil, more than 90% of the impurities in the insulating oil are fiber impurity particles. Therefore, domestic and foreign scholars have mainly carried out research on the insulation ability of insulating oil containing fibrous impurities particles at rest. However, under the influence of forced-oil and forced-air cooling (OFAF) or forced-directed-oil and forced-air cooled (ODAF), the insulating oil actually used in large transformers is always in the flow state, which leads to the change of the movement characteristics of fiber impurity particles suspended in the insulating oil. Therefore, the influencing factors of the movement characteristics of fiber impurity particles in oil flow state are studied in this paper. First of all, through the force analysis of fiber impurity particles in flowing insulating oil, this paper uses the dynamic analysis method to build a solid-liquid two-phase flow multi physical field model of single particle fiber impurity moving in flowing insulating oil. Secondly, the corresponding formula is added to each physical field, and the geometric model is divided. Finally, the trajectory of fibrous impurity particles in oil flow is obtained by calculation. In this model, the solid-liquid two-phase flow multi physical field model is used to solve the problem of insulating oil flow. In order to study the movement characteristics and influence characteristics of single particle fiber impurities under high-voltage DC field under different particle size, electric field amplitude, oil flow velocity, oil temperature, initial velocity and position conditions. By changing the motion parameters in the physical field, each influencing factor is explored. The following conclusions can be drawn through simulation analysis: (1) The transverse motion of fiber particles is only related to the electric field force. The increase of electric field strength, particle size and oil temperature directly or indirectly leads to the increase of electric field force, which leads to the acceleration of fiber particles' lateral movement speed, the denser the round-trip movement tracks between the plates, and the more times they collide with the electrode surface. (2) With the increase of oil flow rate, the longitudinal displacement of the trajectory of fiber impurity particles increases, and the number of collisions with the electrode surface decreases; The initial velocity of fiber particles only affects the maximum velocity, but has no effect on the number of collisions between particles and electrodes. In the uniform electric field, the change of the initial position of the fiber particles has no effect on its motion characteristics. (3) The oil flow rate has a great influence on the movement of fiber impurity particles. Fiber impurity particles with diameter 50 μm will hardly collide with the electrode under 10 kV/cm electric field and 0.4 m/s oil flow velocity. It shows that it is difficult to form impurity particle bridges under this condition. The flow rate of insulating oil is a key factor to be considered in the study of the aggregation characteristics of fibrous impurities in the insulating oil of large power transformers.;
张国治, 闫伟阳, 王堃, 陈康, 张晓星. 流动绝缘油中纤维杂质颗粒运动特性仿真研究[J]. 电工技术学报, 2023, 38(9): 2500-2509.
Zhang Guozhi, Yan Weiyang, Wang Kun, Chen Kang, Zhang Xiaoxing. Simulation Research on Movement Characteristics of Fiber Impurity Particles in Flowing Insulating Oil. Transactions of China Electrotechnical Society, 2023, 38(9): 2500-2509.
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2023, Vol. 38 
