Effect of load current on leakage flux of transformer with geomagnetically induced current

Abstract

Geomagnetic storms caused by solar activity can induce geomagnetic-induced current (GIC) in the power grids. The flow of GIC in the power transformer winding can cause half-cycle saturation of transformer. This saturation can cause distorted exciting current, transformer overheat, and some additional power system problems. There will also be more leakage flux leaving the core and entering into the tank due to GIC. This will cause large tank loss and overheat the transformer. Besides GIC, the leakage flux is also related to the transformer load current. This paper presents a 2D finite-element transformer model. Based on the finite element model, the transformer leakage flux and the tank loss caused by GIC with different transformer load current are studied. As a consequence of GIC, the transformer power factor and the magnitude of transformers load current have an important effect on the leakage flux of transformer. © 2010 John Wiley & Sons, Ltd.