Space weather effects on power systems

Abstract

Space weather disturbances cause geomagnetic field variations that induce electric currents into power transmission systems on the ground. These geomagnetically induced currents (GIC) flow to ground through the windings of power transformers where they produce extra magnetic flux that can saturate the transformer core. This leads to transformer heating, increased power demand, and ac harmonic generation, which can interfere with power system operation. This paper examines the magnetic disturbances on March 24, 1940, February 11, 1958, August 4, 1972, and March 13, 1989 that were responsible for the most significant power system effects. The blackout of the Hydro-Québec system on March 13, 1989 was due to an enhancement of a westward substorm electrojet resulting from loading and unloading of energy in the magnetosphere. Power system effects, including transformer overheating, later on March 13 can be attributed to an eastward convection electrojet caused by the ‘directly- driven’ flow of energy from the solar wind. Power system problems during the earlier disturbances are also shown to be caused by rapid changes of the convection electrojets. This shows that the convection current systems, as well as substorm currents, need to be included when predicting space weather effects on power systems.