To reduce the malfunction probability of the heavy gas in compact transformer due to the transient impulse from power grid

an ATP/EMTP simulation model is built using actual parameters of a substation to calculate the short-circuit current when flashover on different tower insulator string form stable arc. The short-circuit current is used to accurately predict the range and probability of heavy gas malfunction caused by lightning stroke on transmission line. Consequently

three protection methods

i.e.

enhancing the line insulation

connecting small inductors in series before the inlet of transformer

and connecting small reactors at neutral points of transformer

are proposed to restrict short-circuit current and reduce gas malfunction. Moreover

the effects of the proposed methods on actual power grid are analyzed to obtain a feasible scheme. It is shown that integrated usage of the three methods can achieve significant effectiveness in restricting the short-circuit current and reducing the malfunction probability of heavy gas in compact transformer.