覆膜对GIS中自由导电微粒运动行为的影响

发布时间：2018-07-17 21:02

【摘要】：以SF6气体为绝缘介质的气体绝缘金属封闭系统(Gas Insulated Metal Enclosed System,即GIS)具有性能稳定、可靠性高、传输容量大、损耗小、环境友好等优点,在特高压输电和离岸大规模风电输送等领域都有巨大的应用前景。GIS在生产、运输、运行等过程中由于设备振动、摩擦、解吸附等不可控制因素将不可避免地产生金属微粒,对GIS绝缘性能产生严重影响,具体表现为:1)沉积在外腔体表面的金属微粒将畸变其电场分布,引发内部局部放电;2)受电场力的作用在GIS腔体内发生定向移动,减小间隙距离,引发间隙击穿;3)定向移动并附着于绝缘子表面,畸变绝缘子表面电场分布,引发沿面闪络。相关研究表明,GIS中存在金属微粒时,可导致其内部绝缘强度下降90%,严重影响GIS运行的稳定性和可靠性。外腔体内表面覆膜是抑制金属微粒运动、改善金属微粒污染问题的一种重要措施。覆膜后,微粒与电极间的碰撞特性、电荷量、启举电压可能会发生改变,本文对此展开研究。根据运动学原理,搭建了碰撞系数测量平台,研究了覆膜后微粒与电极表面的碰撞恢复系数。分别获得了粒径、碰撞速度、覆膜材料和覆膜厚度对碰撞系数的影响规律,并进行了回归分析。实验表明,通过采用硬度小弹性好的硅橡胶绝缘层可以达到控制微粒与电极碰撞后弹起高度的目的。基于法拉第笼,搭建了直流电压下空气中微粒带电量测量实验平台,获得了覆膜对微粒带电量的影响规律。对不同电极覆膜(PET膜、硅橡胶膜等)时的带电量进行了测量,发现覆膜并不影响微粒的最终带电量,只是延长了微粒的充电时间。根据覆膜后微粒与薄膜间的传导带电机理,对上述结果进行了解释。本文建立了覆膜后金属微粒启举实验平台,获得了直流电压下空气中微粒的启举电压。实验发现覆膜对微粒有明显的静电吸附作用,使得启举电压明显提高;研究了薄膜材质、厚度对微粒启举电压的影响。实验表明,电极表面覆上同样厚度的硅橡胶膜比PET膜情况下的启举电压大,随着薄膜厚度的增大,启举电压有增大趋势,但效果不明显。实验发现,覆膜后微粒的运动会明显减弱,且微粒将出现延时启举和间歇起跳现象。最后本文指出了研究中存在的不足及尚待研究的问题,对GIS中金属微粒污染无害化研究做了展望。
[Abstract]:The gas insulated metal sealing system (Gas Insulated Metal Enclosed System, GIS) with SF6 gas as insulating medium has the advantages of stable performance, high reliability, high transmission capacity, small loss and friendly environment. It has great application prospects in UHV transmission and offshore large-scale wind power transmission, such as.GIS in production, transportation, operation and so on. In the process, the metal particles will inevitably be produced due to the incontrollable factors such as equipment vibration, friction, desorption and so on. It has a serious effect on the insulation performance of GIS. 1) the metal particles deposited on the surface of the outer cavity will distort the electric field distribution and cause internal partial discharge; 2) the directional shift of the electric field forces in the cavity of the cavity. Moving, reducing gap distance, causing gap breakdown; 3) moving and attaching to the insulator surface, distorting the distribution of electric field on the surface of insulators and triggering the flashover along the surface. The related research shows that the internal insulation strength of the GIS can be reduced by 90% when there is metal particles in the surface, which seriously affects the stability and reliability of the operation of the external cavity. It is an important measure to restrain the movement of metal particles and improve the pollution of metal particles. After the film, the collision characteristics between the particles and the electrodes, the amount of charge and the lift voltage may change. This is a study in this paper. According to the principle of kinematics, the collision coefficient measurement platform is set up, and the collision recovery of the particles and the surface of the electrode after the film is studied. The influence of particle size, collision speed, film mulching material and film thickness on the impact coefficient is obtained, and the regression analysis is carried out. The experiment shows that the purpose of controlling the height of the particles after the collision between the particles and the electrode can be achieved by using the good hardness small elastic silicon rubber insulating layer. Based on the Faraday cage, the direct current voltage is set up. The influence law of the film on the charge quantity of the particles was obtained by the experimental platform of measuring the charge quantity of particles in the air. The charge quantity of the film (PET film, silicone rubber film, etc.) was measured by different electrodes. It was found that the film did not affect the final charge of the particles, but the charging time of the particles was prolonged. The conduction band between the particles and the film after the film was used. The results are explained by the motor theory. In this paper, the open lift test platform of metal particles after the film is established, and the starting voltage of the particles in the air under DC voltage is obtained. It is found that the film has obvious electrostatic adsorption on the particles, which makes the lift voltage obviously improved, and the effect of the material and thickness of the film on the lift voltage is studied. The experiment shows that the opening voltage of the silicon rubber film with the same thickness is larger than that of the PET film. With the increase of the thickness of the film, the lift voltage is increasing, but the effect is not obvious. It is found that the movement of the particles will be obviously weakened after the film mulching, and the particles will have the phenomenon of delay lifting and intermittent take-off. Finally, the paper points out the research. The existing deficiencies and problems to be solved are discussed. The prospect of harmless research on metal particle pollution in GIS is prospected.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM595

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