Study on GIL Grounding Current Characteristics Based on Dynamic Arc Model

The transportation and installation of insulated transmission lines (GIL) may lead to insulation defects, which can subsequently cause internal arc faults. The grounding current characteristics of internal arc faults are of great significance for insulation diagnosis and fault location of GIL equipment. In response to the above issues, the paper proposed a GIL simulation model based on dynamic arc theory and conducted a study on the grounding current characteristics under different operating conditions. By integrating the Mayr-Schwarz arc and Bergeron transmission line theories with the design parameters of GIL, an EMTP simulation model for normal operation and internal arc fault conditions was established, and the grounding current characteristics of the three-phase short-circuit busbar under the two conditions were analyzed. The results indicate that under normal operating conditions, the short-circuit busbar will carry approximately symmetrical three-phase power frequency currents, and the amplitude of the grounding current does not exceed 1% of the rated load current. In the event of an internal arc fault within the GIL equipment, a fault current traveling wave will propagate along both sides of the GIL tunnel, and the grounding current will undergo a sudden change in the nanosecond range, followed by a transient current decay process with amplitudes of up to 7kA in the microsecond range. Finally, based on the simulated pulse test of GIL, the feasibility of the fault location scheme for GIL based on transient current method was verified. The simulation results provide a reference for the insulation design and fault location of GIL equipment.