Determination of the spectrum of frequencies generated by a saturated transformer

This paper develops a technique to model the frequency response of a saturated transformer. This technique is used to determine the range of frequencies that will be generated when a transformer experiences saturation due to an injection of typically low frequency currents. This paper examines the case when a power transformer is saturated due to geomagnetically induced currents (GIC) caused by solar storms. The proposed technique is validated for a study system utilizing EMTDC/PSCAD simulations. The results from this technique are also correlated with those from a Hydro Quebec study. This technique will be useful in understanding the impact of transformer saturation on neighbouring equipment and as well as on FACTS controllers, and help design appropriate mitigation strategies.