In order to realize the miniaturization

compactness and environmental protection of GIS busbar

we researched the compact design of 330 kV GIS bus under mixed gas medium. First

the busbar structure was determined to be a three-phase in one tank type according to the principle of miniaturization; the existing research results of SF

6

/N

2

mixed gas

combined with engineering application experiences

were used to determine the SF

6

/N

2

mixed gas mixture ratio

and the SF

6

/N

2

mixed gas insulation margin criterion proposed. Based on this

an insulatio

n margin calculation model when multi-physics coupling such as flow loss

gas flow and gravity is taken into consideration was established. In order to solve the problem accurately

we took into account the influence of the synergistic effect of the mixed gas on the physical properties of the material

and adopted the Aspen software to calculate the physical properties of the mixed gas and fit the law of its change with temperature. In order to obtain the optimal compact bus structure

a compaction coefficient was defined and parametric design method was used to obtain the variation law of the insulation margin with the compaction coefficient. The research results show that the proposed compactness principle can effectively guide the size design of the three-phase in one tank busbar. The insulation level of 330 kV designed GIS busbar under the condition of SF

6

/N

2

mixed gas medium meets the requirements. In the most compact size

the bus volume can be reduced by 37%

and the amount of SF

6

gas can be reduced by 80%.