| Induced "dc" currents due to geomagnetic storms have caused power system blackouts and transformer damages in the past. Statistically, large geomagnetic storms follow a 10-11 year sunspot cycle, but geomagnetic disturbances with significant impacts can occur at any time. The geomagnetically induced currents (GIC) have wide range of detrimental effects on otherwise normal operation of power systems, communication systems, railway systems, and can cause oil and gas pipeline corrosion. This thesis presents a method of estimating the magnitudes of terrestrial voltages; which is based on solving the magnetic diffusion equation. The method predicts the oft-quoted figure of "1 volt per kilometer" for the range of geomagnetic field variations (magnitudes and frequencies) and ground resistivity frequently encountered. The prediction formula has been validated by the plane wave method. Geomagnetic storms have the tendency to disrupt the normal operation and even lead to major power outages depending upon the intensity of geomagnetic activity; whereas the major effects include transformer equipment damage, relay tripping, SVC failures resulting in minor or major power outages. |
