Assessment of geomagnetic hazard to power systems in canada

This paper presents an assessment of geomagnetic hazard on the five largest power systems in Canada. From east to west these are: Nova Scotia Power, Hydro-Quebec, Ontario Hydro West System, Manitoba Hydro, and the northern B.C. Hydro system. The aim of this study was to determine how frequently, and where in a system, large geomagnetically induced currents (GIC) could be expected. To do this, an analysis was made of the spectral characteristics of the magnetic field variations that cause GIC, and a review was made of published magnetotelluric soundings in order to determine conductivity models for different parts of the country. The magnetic field spectra and the conductivity information were then used to determine the electric fields produced during geomagnetic disturbances. A relation was determined between electric field magnitudes and the magnetic activity index, Kp so that statistics for Kp could be used to determine the occurrence rates of large electric fields. Power system models were used to determine the GIC produced by the '1-year' and '10-year' electric fields experienced by each power system.