Solving old problems with new technology: How to monitor and measure GIC and OPD currents

Abstract

Geomagnetically-induced currents (GICs) are produced by a naturally induced geo-electric field during geomagnetic disturbances. An extreme example of this type of occurrence happened in March 1989, during one of the largest geomagnetic disturbances of the twentieth century. Rapid geomagnetic field variation during this storm led to the induction of electric currents in the Earth's crust. These currents caused wide-spread blackouts across the Canadian Hydro-Quebec power grid, resulting in the loss of electric power to more than 6 million people. If a similar storm-induced blackout had occurred in the Northeastern United States, the economic impact could have exceeded $10 billion. On average, 200 days of strong to severe geomagnetic storms that could produce GICs on the surface of the Earth can be expected during a typical 11-year cycle. However, knowing exact levels of induced currents in power grid infrastructure during a geomagnetic event requires knowledge of deep earth conductivities and transmission line design parameters. GICs are also difficult to measure as they are non-cyclical and slowly varying over time and most of the power systems architecture relies on magnetic transformers tuned for sinusoidal signals.