gas insulated transmission lines, power overhead lines, power transmission lines, gas insulated switchgear, earthing, underground GIL pipelines, grounding requirement value, integrated grounding system design, voltage 550.0 kV, current 4000.0 A, corresponding grounding scheme, layout, grounding design, advanced power transmission mode, Engineering (General). Civil engineering (General), TA1-2040

Gas insulated transmission line (GIL) is an advanced power transmission mode. Since the extension of this kind of equipment is relatively long, the grounding design and layout of the GIL will have a direct impact on personal safety and the stability operation of equipment, which should be given full attention. In order to ensure the safe and stable operation of GIL, it needs reasonably design and arrangement of the integrated grounding system in the GIL pipelines. This study designed corresponding grounding scheme for the integrated grounding system of underground GIL pipelines combined with a 550 kV/4000 A GIL. The corresponding simulation model of the integrated grounding system was established with specific parameters of the GIL. The calculation results show that the grounding resistance of the integrated grounding system is 0.217 Ω, which is less than the grounding requirement value of 1 Ω, and it reduces 28.9% compared with the simulation model without considering the natural grounding body. In addition, the step voltage and touch voltage are reduced by 79.91 and 48.97%, respectively. The research results can give some references for the integrated grounding system design of GIL engineering.