Overview of Geomagnetic Storm Coupling to a Power Grid

It is well known that a power grid can be vulnerable to collapse and damage from geomagnetic storm disturbances. However there is considerable uncertainty in how a power grid would respond to a future storm - including possibilities of shutdowns ranging from hours to months or years. This paper discusses the factors involved in the generation of the geomagnetically induced currents (GICs) that can, under severe circumstances, damage large transformers in a power grid.