Effect of geomagnetically induced current on the loss of transformer tank

Abstract

Geomagnetically induced current (GIC) can cause half-cycle saturation of transformer. The saturation can increase the stray flux entering into transformer tank, so the tank loss will increase. This study presents a two-dimensional finite element (2D FE) transformer model and the losses of tank wall, tank top and tank bottom are computed, respectively. Based on the 2D FE magnetic field, the factors that influence the tank loss of transformer with GIC are discussed. The influences of magnetic shunt, transformer types, step-up transformer or step-down transformer, and transformer power factor on the tank loss are analysed in detail. As a consequence, the transformer types and transformer power factor have large influence on the increase of tank loss caused by GIC.