GLOBAL STUDY OF GEOMAGNETIC INDUCED CURRENT USING TIME DERIVATIVES OF GEOMAGNETIC FIELDS

摘要

This report investigates variations in time derivatives of the geomagnetic field observed during great storms known tohave caused disruption and to have had other adverse effects on power grids. The geomagnetic storms considered werethose of 24th November 2004, 30th October 2003 and 28th October 2004, which occurred during the Autumnal event, andalso 7th April 2000 and 31st March 2001 which occurred during the Spring events. Geomagnetic field variations areassociated with geoelectric field variation at the surface of the Earth which is influenced by the conductivities ofdifferent structures of the Eartha€?s interior. The induced electric field is proportional to the rate of change of thegeomagnetic field, which explains why many researchers have used time derivatives of the geomagnetic field as ameasure of GIC strength. Koen and Gaunt (2002) established that variation exceeding 30nT/min of the time derivativesof the geomagnetic field component appears to be significant, causing undesirable consequences in power grids.