Geomagnetic disturbances due to solar activity may lead to geomagnetically induced currents (GIC) in power system networks. These GICs are quasi-DC (0.01Hz to 0.5Hz) and can saturate the core of power transformers.

The saturation of the core due to GICs leads to increased magnetizing current peaks that are up to several time the nominal current of the transformers.

The high magnetizing currents significantly increase the reactive power demand of the transformers and high amounts of harmonic are injected into the power system.

Moreover, these high quasi-DC flux on the core and the associated high magnetizing currents overheat transformer windings and clamping structure, increasing overall losses.voltage and current harmonics

IEEE C57.163 Guide

IEEE issued the standard [IEEE Std C57.163-2015 – IEEE Guide for Establishing Power Transformer Capability while under Geomagnetic Disturbances]. In this document, guidelines are provided to evaluate a transformer design’s resilience to GICs..

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