A high-frequency model of an oil-immersed transformer, and its use in lightning surge analysis

Abstract

A circuit model of an oil‐immersed transformer for use in surge analyses in the high‐frequency region is proposed, and its effectiveness is evaluated by comparison with measurements on a model winding. The circuit model is used for lightning surge analyses of a 500‐kV substation, and the effect of transformer modeling on the lightning surge voltage at the transformer terminals is investigated. When the new circuit model is used for transformer modeling, the peak value of the surge voltage is lower but the rate of voltage rise is higher than in conventional transformer modeling by a lumped capacitance. This difference can be explained in terms of the charging of capacitances in the transformer model. © 2000 Scripta Technica, Electr Eng Jpn, 134(1): 28–35, 2001