电工技术学报  2024, Vol. 39 Issue (17): 5534-5544    DOI: 10.19595/j.cnki.1000-6753.tces.231050
高电压与放电 |
流-电耦合场中金属颗粒群的荷电计算及影响因素研究
张宁, 王鹏, 刘智捷, 刘恭智, 贺博
西安交通大学电气工程学院 西安 710049
Study on the Charge Calculation and Influencing Factors of Metal Particle Groups in Fluid-Electric Coupling Field
Zhang Ning, Wang Peng, Liu Zhijie, Liu Gongzhi, He Bo
School of Electrical Engineering Xi'an Jiaotong University Xi'an 710049 China
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摘要 绝缘油中金属颗粒的荷电量分布是研究颗粒运动特性以及绝缘油中局部放电与击穿行为的关键。该文搭建了油道模拟观测系统,采用动力学分析的方法,构建了液固耦合系统中金属颗粒的运动模型,并在此基础上提出通过粒子图像测速(PIV)来计算颗粒荷电量;分析了不同油流速度、电压等级以及电压类型对颗粒荷电量的分布影响以及作用机理。结果表明,基于PIV计算出的油中颗粒的荷电量与传统模型的计算结果数量级相近,绝缘油中金属颗粒荷电量占比分布曲线接近高斯分布,这是由于颗粒与颗粒之间碰撞也会发生电荷转移或中和。在直流电压下流速增加会阻碍颗粒之间的电荷传递,增加颗粒与极板碰撞概率,导致颗粒荷电量减小。电压等级增加则会使颗粒群的流线由平缓变为振荡,颗粒荷电量普遍增加。相比于直流电压,在交流电压下,荷电量大的颗粒占比较多。
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关键词 粒子图像测速金属颗粒绝缘油液固耦合荷电分布    
Abstract:In the life cycle of power equipment, the insulating oil is easy to mix with various solid impurity particles such as metal and fiber, which will cause electric field distortion and insulation balance failure of equipment. Therefore, considering that compared with non-metallic particles, metal particles have a greater impact on partial discharge and arc breakdown of oil, this paper proposes a method to derive the charge of particles by analyzing the force model of metal particles on the basis of discrete particle model, and reveals the influence of electric field intensity, voltage type and flow velocity on the charge distribution of metal particles.
Firstly, the internal oil channel environment of power transformer was simulated and the experimental observation platform for particles in oil was built. Secondly, the force model of metal particles in the fluid electric coupling system was established combined with fluid dynamics. The formula for calculating the charge of metal particles under experimental conditions was derived through the formula. Thirdly, the particle image velocimetry (PIV) system was used to capture the cloud picture of particle swarm velocity and streamline, and the velocity and acceleration of metal particles were calculated through the streamline of particles and the finite difference method, so as to calculate the charge of particles, which was close to the charge of particles calculated by the traditional model. Finally, by changing the applied voltage, oil flow rate and voltage type, the charge value and distribution of metal particles in the oil flow were calculated and counted.
The experimental results show that when the flow rate of insulating oil is 0.15 m/s, the maximum charge of particles is 0.17 pC, and the proportion of particles with the absolute value of charge greater than 0.01 pC is 36%, while when the flow rate is 0.3 m/s, the maximum charge of particles is -0.13 pC, and the proportion of particles with the absolute value of charge greater than 0.01 pC is 29%, which may be due to the increase of horizontal drag force on particles when the flow rate of oil increases. The time of particles flowing through the electric field region is shortened. When the voltage is -10 kV, the maximum charge of particles is 0.05 pC, and the proportion of particles whose absolute value of charge is greater than 0.01 pC is 12%. When the voltage is -20 kV, the maximum charge of particles is 0.09 pC, and the proportion of particles whose absolute value of charge is greater than 0.01pC is 25%. When the voltage is -30 kV, the maximum charge of particles is 0.17 pC, and the proportion of particles whose absolute value of charge is greater than 0.01 pC is 36%. The acceptable explanation is that the increase of electric field intensity leads to the increase of collision probability between particles and electrodes. When the applied voltage is AC, the proportion of particles with the absolute value of charge greater than 0.01 pC is about 10%, and the maximum charge of particles is 0.03 pC.
Through the above analysis, it can be concluded that: (1) The maximum charge of particles is in the same order of magnitude as the traditional model, but the distribution curve of the charge proportion of particles is close to the Gaussian distribution. (2) With the increase of insulating oil flow rate, the movement time of particles in the electric field between electrodes is reduced, resulting in the reduction of the probability of particles colliding with electrodes in the same time interval, and the proportion of particles not colliding with electrodes is increased. (3) The velocity component of particles in the vertical direction increases, the collision between particles and electrodes becomes frequent, and the charge of particles generally increases. (4) When the applied voltage is AC, the particles with large charge account for less.
Key wordsParticle image velocimetry    metal particles    insulating oil    liquid solid coupling    charge distribution   
收稿日期: 2023-07-05     
PACS: TM855  
基金资助:国家自然科学基金资助项目(51977170)
通讯作者: 贺 博 男,1976年生,教授,博士生导师,研究方向为高电压与绝缘技术领域的基础理论、电力设备绝缘性能分析与绝缘结构优化设计、复合电介质形态结构与性能关系等。E-mail:hebo@mail.xjtu.edu.cn   
作者简介: 张 宁 男,2000年生,硕士研究生,研究方向为绝缘介质特性以及电力设备绝缘结构仿真。E-mail:zi1213123321456@stu.xjtu.edu.cn
引用本文:   
张宁, 王鹏, 刘智捷, 刘恭智, 贺博. 流-电耦合场中金属颗粒群的荷电计算及影响因素研究[J]. 电工技术学报, 2024, 39(17): 5534-5544. Zhang Ning, Wang Peng, Liu Zhijie, Liu Gongzhi, He Bo. Study on the Charge Calculation and Influencing Factors of Metal Particle Groups in Fluid-Electric Coupling Field. Transactions of China Electrotechnical Society, 2024, 39(17): 5534-5544.
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