Influence of geometry and operation conditions on the surface charge characteristics of DC‐GIL spacer

Abstract

The surface charge characteristics of a ±200 kV gas-insulated transmission lines spacer are studied to understand the influence of geometry, ion transportation, applied voltage, and gas pressure on the surface charge distribution. The simulation result indicates that the geometry simplification would affect the surface charge distribution. A millimeter-level protrusion on the spacer causes an increase of 20 μC m−2 in charge density. A difference of 10 μC m−2 is found between the simulations based on the measured and calculated ion mobility. Moreover, it is found that the identical surface charge distribution cannot be achieved with the downsized model based on the identity of field strength, since ion transportation is affected by the scaling of geometry. The influence of gas pressure on the ion migration results in an initial excitation to the field variation, which further promotes the variation of surface charge via the dominative bulk conduction. Thus, with increasing pressure from 0.3 to 0.6 MPa, an increase of 8.4 μC m−2 is found on the convex surface, while a decrease of 5.5 μC m−2 is found on the concave surface. This investigation would be helpful for the simulation and experiment concerning the surface charge characteristics of spacers.