Efficiency Analysis of Particle Trapping for ±320-kV GIL

If metal particles move to the surface of the spacer in a dc gas-insulated line, they will distort the original electric field, increasing the instability of gas-insulated transmission line (GIL) during long-term operation. By setting up particle traps in front of the spacer and on the inner surface of the casing, a low field strength area can be formed to suppress particle movement. However, there is currently no clear method for analyzing trap efficiency. Based on the ±320-kV GIL physical platform, the research indicates that the total number of particles trapped is negatively correlated with the initial distance of the particles from the trap (5, 15, 25, and 35 cm). On the side close to the spacer below the trap, the 5% of the total trapped particle length of the trap, that is, the “GIL spacer safety zone,” is positively correlated with the trap porosity (13.4%, 24.1%, and 32.3%). The coating below the trap can increase this area’s length to some extent. Based on simulation calculations, it was verified that stationary particles at the initial moment will not jump due to external voltage when they are below the designed particle trap. The conclusions of this article provide guidance for clarifying particle trap design methods and evaluation criteria, as well as for developing stable and reliable dc gas-insulated equipment.