Metallic particles in DC gas-insulated transmission lines

Abstract Metallic particles have a significant influence on the insulation reliability of DC gas-insulated transmission lines (GILs). This paper first outlines metallic particles in GIL, predominantly in spherical, linear-like, and dust forms, from the perspectives of electrodynamic forces and motion characteristics. Then, the mechanisms and processes of gap breakdown and surface flashover induced by different types of metallic particles are analyzed. Furthermore, particle suppression technologies, such as particle traps, surface coatings, and repelling electrodes, which can reduce the likelihood of particles moving near insulators and mitigate their hazardous effects, are discussed. Finally, the use of electrical, acoustic, and optical sensing technologies to monitor the operational status of GIL is examined, thereby enabling early warning of metallic particle contamination. This paper provides an overview of the progress and future research directions in metallic particle pollution and its suppression and detection technologies in DC GIL, offering guidance for the development of stable and reliable gas-insulated transmission equipment.