Geomagnetic Storms Can Threaten Electric Power Grid

[Linnea]

http://www.agu.org/sci_soc/eiskappenman.html

The sprawling North American power grid resembles a large antenna, attracting electrical currents induced by giant solar storms. Severe space weather occurring during solar cycles has the potential to cause a large-scale blackout in North America.

by John G. Kappenman, Minnesota Power, Duluth, Minn.; Lawrence J. Zanetti, Johns Hopkins University, Applied Physics Laboratory, Laurel, Md.; and William A. Radasky, Metatech, Goleta, Calif.


Since the turn of the century, society has relied more heavily on electricity for meeting essential needs. Three large, interconnected grids that span the continent provide rapid response to the diverse energy demands of users in the United States and Canada. This unique energy service requires coordination of electrical supply, demand, and delivery—all occurring at the speed of light.

Disturbances caused by solar activity can disrupt these complex power grids. When the Earth's magnetic field captures ionized particles carried by the solar wind, geomagnetically induced currents (GIC) can flow through the power system, entering and exiting the many grounding points on a transmission network. GICs are produced when shocks resulting from sudden and severe magnetic storms subject portions of the Earth's surface to fluctuations in the planet's normally stable magnetic field. These fluctuations induce electric fields in the Earth that create potential differences in voltage between grounding points—which causes GICs to flow through transformers, power system lines, and grounding points. Only a few amps are needed to disrupt transformer operation, but over 100 amps have been measured in the grounding connections of transformers in affected areas.

Article continues...see link above. There is an 'anatomy of a blackout' describing the blackout of 'the great geomagnetic storm of March 13, 1989, plunged the entire Hydro Quebec system, which serves more than 6 million customers, into a GIC-triggered blackout'