Particle-initiated breakdown in gas-insulated co-axial configuration

Abstract

This paper presents theoretical investigation of conducting particle-initiated breakdown in gas-insulated coaxial configuration under high direct voltage. The presence of contaminating conducting particles could seriously deteriorate the dielectric strength of high voltage gas-insulated substations (GIS) and gas-insulated transmission lines (GITL). This deterioration depends on the shape of the particle, the type and the pressure of the gas insulation, and the electric field. The calculated breakdown voltage initiated by particle is obtained by streamer breakdown criterion. The breakdown voltage calculation calls first for an accurate calculation of the electric field on and around the particle surface. The investigated gap is a three-dimensional field problem due to the asymmetrical space arrangement of the particle inside the gap. The particles studied are of many different shapes and sizes such as spheres, filamentary (wire) particles and fine spheres simulating the surface roughness. To solve this problem, charge simulation technique is used. The calculated field values are utilized in evaluating the breakdown voltage. The effects of varying the field nonuniformity, particle shape and size, gas type and pressure on the breakdown voltage are investigated. The calculated breakdown voltage values agree satisfactorily with those measured experimentally and with those obtained theoretically before.

Partial discharge characteristics of free moving metal particles in gas insulated systems under DC and AC voltages

“…In an AC electric field, particle charging is affected by the collision time between the particle and the electrode surface, the discharge time, and the power cycle. The local quantity of a particle has great randomness [47][48]. Currently, there is no perfect research scheme.…”

Restraining Surface Charge Accumulation and Enhancing Surface Flashover Voltage through Dielectric Coating

“…The charging of conductive particles is explored from the following three asp the conductive particle charge in a high-voltage electric field, the influence of sur coating materials on the amount of charging, and the impact of the charging process The charge transfer and defects/deterioration due to conductive particles in gas-insulated systems were studied in the early 21st century through modeling. M. M. El Bahy et al analyzed conductive particle charging on the electrode surface and coating surface to investigate the effects of the particle shape and electric field distribution on the charging characteristics [16]. The conductive particle motion behavior and collision characteristics in a wedge-shaped, slightly uneven electric field were numerically studied in a coupled manner to explore the gas-insulated system's structural and field distribution characteristics and the conductive particle motion law near the insulating support [10].…”

“…After coating, there are three main mechanisms of particle charging on the surface: (1) the surface of the medium has a charge, and the particles are charged by contact with the electrode film; (2) the particles are charged by the electric current in the medium; (3) the discharge of particles is based on the micro-discharge between the particles and the medium. Reference [16] shows that after the DC system is coated, the particle charge is essentially generated by the film's conduction. C. Li et al established a conductive and micro-discharge model and calculated the charge of metal particles using the different models [2,12].…”

“…From a quantitative perspective, researchers around the world have always assumed that the particle shape does not affect the particle mechanism or force types and often study spherical particles [46,47]. To find the source of metal particle charging in a uniform DC field, researchers have studied the charging of metal particles when they are stationary on the electrode surface [16,27]. They used the potential function caused by multi-pole expansion to solve the partial differential equations in the electrostatic field zones and obtained the spherical metal particle charge q b :…”

“…Since the advancement of SF 6 application in the mid-1960s, Western European countries (BBC of Switzerland and Delle of France) and Japan have directed more attention to GIS development. The Soviet Union and China completed 110 kV GIS research and trial production in the early 1970s; their initial research focused on withstand tests [9][10][11][12][13][14][15][16] and test methods [17][18][19].…”