Two-Dimensional Charge Characteristics in HVDC GIL Insulators: A Simulation Study

The long-term synergistic effects of high-voltage direct current (HVDC) and temperature gradients inevitably stimulate charge accumulation in gas-insulated transmission line (GIL) insulators, which significantly increases the risk of insulation failure. Due to the limitations in charge measurement techniques, it is crucial to develop effective methods for accurately simulating and evaluating the dynamic charge behaviors of GIL insulators under complex operating conditions. In this study, we present a 2-D bipolar charge transport and interaction (2-D BCTI) model that accounts for both space charge and surface charge dynamics. Such a model is employed to investigate the charge behaviors of HVDC GIL insulators under varying electric fields, polarization time, and voltage polarities. Our findings indicate that higher voltages and extended polarization time lead to increased charge migration and localized accumulation within the insulator. Further analysis reveals that the surface potential at the high-voltage terminal interface is predominantly influenced by the tangential current ( ${J}_{\text {s}}$ ) along the insulator’s surface and bulky current ( ${J}_{\text {v}}$ ) passing through the insulator. In other regions of the basin insulator, such as the shielding ring and grounding terminal, ${J}_{\text {s}}$ is the dominant factor. This study provides valuable theoretical insights into the interaction between surface and space charge, offering a foundation for optimizing the insulation design of HVDC GIL systems.