Overview of the impact of intense geomagnetic storms on the U.S. high voltage power grid

This paper provides an overview of the threat of intense geomagnetic storms created by solar activity to high voltage power grids on the Earth. Given a description of the time and spatial variation of the geomagnetic field (past, present or future), it is possible to model the response of any specific high-voltage grid with a high level of accuracy. It is also clear from the available data that the higher the voltage of the AC power system, the more vulnerable that system is to a particular geomagnetic storm. Given the ability to model and with an understanding of transformer behavior, it is possible to design protection for high-voltage grids against this unique threat.