Research On Motion Behavior And Characteristics Of Metal Particle In DC GIS

In the process of production,assembly,transportation and maintenance of gas insulated switchgear,metal particle pollution inevitably occurs,which will cause great harm to the insulation performance of GIS.The shapes of these particles are mainly linear,powdery,spiral and irregular,and their length is in the millimeter scale,and their width is in the order of 100 microns.When apply voltage on GIS,metal particles stationary on the surface of the electrode may roll,jump or even lift and carry out reciprocating collision between the electrodes under the action of electric field,and the motion is the most active under DC voltage.When metal particles move freely,they may induce field intensity distortion,change space charge distribution and trigger micro-discharge in the air gap,thus then cause air gap breakdown.In addition,the particles moving and attaching to the surface of basin insulator will aggravate the charge accumulation on the surface of insulator,trigger flashover discharge along the insulator surface,and finally cause breakdown of the whole insulator.Therefore,the research on the motion behavior and characteristics of metal particle in DC GIS has certain engineering value and practical significance,and this aspect has been researched in the paper.In the process of establishing the simulation model of metal particle movement,this paper analyses the charging mechanism and force condition of particles under DC voltage,uses hydrodynamic theory to analyze the value of drag coefficient under different Reynolds number,combines classical collision theory and dynamic contact theory to analyze the inelastic collision process between particle and electrodes,and fully considers the influence of the random angle of collision reflection on the particle velocity change.In order to simulate the motion behavior of spherical particle in the inhomogeneous electric field area in GIS,the force model of particle under wedge-shaped plate electrode is established,and the collision behavior between particle and high voltage electrode is also analyzed.The motion critical voltage and motion process of particle are explored.Finally,the change law of minimum position,jumping point and falling point of particle in the horizontal direction and jumping time of particle under different influence factors such as applied voltage,radius of particle,initial position,angle of electrodes and friction coefficient are emphatically analyzed.The increase of applied voltage and the decrease of particle radius,angle between electrodes will increase minimum position,jumping point and falling point of particle in the horizontal direction and jumping time of particle to a certain extent,which provides theoretical guidance for the layout scheme of particle traps.In addition,the force model of metal particle on the surface of high voltage conductor in coaxial cylindrical electrode system is established to analyze the motion behavior and characteristics of spherical particle in the slightly inhomogeneous electric field area in GIS.Firstly,the motion critical voltage at different initial positions and radius of particle is analyzed.Then,the various motion behaviors and processes of particle under different applied voltages are explored from the point of view of force and energy loss.Finally,the influence of applied voltage,gas pressure,radius and initial position of particle on the angle of particle motion range,transition time of entering "resonance" motion and frequency of "resonance" motion is studied.