What are the effects on mid-latitude power systems from Geomagnetic Storms?
There are two things to consider to evaluate the local interaction with any power grid. The first is a question of the local natural earth-conductivity. Areas that permit natural currents to flow are not very likely to be affected, whereas areas with poor natural conductivity provide a possible opportunity for currents to get into the grid through grounded neutrals of transformers. The other consideration is your proximity to the auroral electrojet. Under G2 conditions the aurora will have expanded somewhat, but not down to mid-latitudes. A G3 storm begins to move the aurora down to lower latitudes to the point where mid-latitude affects are possible. One complication to this is that lines of magnetic latitude do not map exactly with the geographic latitude. Thus, one tends to worry more about the East coast geographic mid-latitudes than the West coast geographic mid-latitudes because the former are closer to the magnetic pole. If you want to see a map of this, look at the relation bet
