The Study On Transformer In Gas Insulated Substation Influenced By Very Fast Transient Overvoltage

Compared with Air Insulated Substation (AIS), Gas Insulated Substation (GIS) has many merits, so it has been applied widely in the world. The Very Fast Transient Overvoltage (VFTO) generated by disconnector operation in gas-insulated switchgear (GIS)can bring same trouble to the equipments in GIS. The VFTO in power system have several or a few nanosecond rise time of surge. When such steep voltage induce transformer or some other equipments, on the one hand this signals can bring very asymmetry distributing voltage along windings or conductor; most of descenting voltage exist in subsection windings or conductor around the input end; and the gradient of the voltage is so high that can damage the insulation between coils in transformer; on the other hand the input voltage which have over one hundred megahertz frequency may arise electromagnetism oscillation; cause overvoltage and damage the insulation between coils or earth insulation inside transformer. The thesis use a multitransmission line model to replace transformer and analyse the distributing voltage along the windings; frist bring forward Order Reduction arithmetic used in calculation cosmical circuit; and reduce computing time.