Study On The Movement Characteristics Of Metal Particles In GIL

In recent years,gas insulated transmission lines(GIL)have been widely used and have attracted much attention.However,the problem of metal particle contamination is limiting the further development of GIL technology.In this paper,studies will be carried out on the laws of metal particle motion in AC and DC GILs and on the electric field distortion of insulated systems,mainly as follows:(1)According to the structure of the GIL and the position of the metal particles,a model of the coaxial cylindrical electrode system was established,and the forces on the metal particles under different electric field distributions were analysed,and the criteria for the lifting conditions of the metal particles in the AC and DC GILs were obtained.(2)A coaxial cylindrical test cavity was constructed and the electric field distribution inside the cavity was simulated and analysed.An experimental study of the motion of linear metal particles under GIL AC voltage was carried out and the motion of metal particles with different lengths and radii was analysed.The results of the study show that the starting voltage is positively related to the particle radius and not to the particle length.After the linear metal particles reach the lifting voltage,the particles first make "small jumps",i.e.small jumps on the surface of the shell,after several small jumps,the particles move through the gas gap and bounce off the high potential guide rod.The length of the metal particles affects the state of motion,the radius of the metal particles affects the intensity of the motion,and since the time-varying nature of the AC voltage,the trajectory and speed of the particles exhibit irregular dynamic characteristics.(3)In order to simulate the movement of metal particles in GIL,a 1:1 coaxial cylindrical electrode test chamber for GIL pipe was designed and constructed,with 252 k V basin insulators sealed on both sides of the chamber.The electric field distribution inside the cavity was simulated and analysed.An experimental study of metal particle motion under negative DC voltage polarity was carried out.The results show that the linear metal particles undergo a ’flyaway’ phenomenon under DC voltage negative polarity.(4)In addition to study the distortion of the electric field distribution of the gas gap by metal particles,a three-dimensional simulation model of the GIL pipe was constructed and finite element analysis was applied to simulate the electric field distribution of metal particles at different locations in the gas gap.The results show that the metal particles located inside the cavity distort the electric field distribution in space.The maximum electric field generated by a particle is negatively related to the radius of the particle and positively related to the length of the particle.When the particle touches the electrode surface,the maximum field strength occurs at the end of the particle away from the electrode surface.The distortion effect is greatest when the particle is in contact with the surface of the high potential guide rod.(5)The electric field distribution along the surface of a basin insulator was simulated when linear metal particles of different sizes and positions are attached to the surface of the insulator.The results show that the linear metal particles exacerbate the electric field distortion along the face of the insulator.The electric field strength on the convex side was influenced by the high voltage inserts,while the concave side is largely unaffected by the particle attachment position.At the same location,the longer the particle,the greater the effect on the electric field distribution along the face of the insulator.