Aiming at the problems existing in conventional substation such as disconnector contact surface overheat caused by dirt

corrosion

oxidation

and Insulation loss caused by leakage of current transformer

taking the Enhe 220 kV substation 110 kV side hybrid gas insulated switchgear（HGIS）equipment retrofit project as an example

the methods are intro-duced for the installation and implementation of HGIS retrofit in a conventional substation

it effectively solves the problems of the new equipment HGIS in the installation and reconstruction of the old conventional substation. The methods presented in this paper

reduce the construction investment and shorten the construction period. By switching out the busbars alternatively

the outage and load loss has been reduced to a minimum

the power grid enterprise economic benefit and social benefit has been a reliable guarantee.