To prevent overvoltage of electrical equipment caused by lightning intruding wave when a high voltage incoming line of transformer substation is struck by lightning

an overall model of lightning intruding a transformer substation is built.Simulations are conducted through PSCAD/EMTDC for three cases-lightning striking steel tower

lightning striking central span of overhead grounding wire

and lightning shielding failure.In each case

the influences of lightning intruding wave on electrical equipment in two conditions are compared.One condition is complete protection by overhead grounding wire

i.e.leading overhead grounding wire to door frame of transformer substation

the other condition is incomplete protection of overhead grounding wire

i.e.overhead grounding wire ends at terminal tower

and lightning rods on transformer substation and terminal tower together protect the rest of the line.The results show that in the latter condition

lightning strike on the span between terminal tower and transformer substation can be effectively prevented

and the back flashover overvoltage due to lightning striking incoming line can also be reduced.