Geomagnetically induced current (GIC) and geomagnetic disturbance (GMD) events are caused by solar flares ejected from the surface of the sun. The ionized atoms of these supersonic plasma streams interact with charged particles in the earth’s atmosphere and induce changes in the earth’s magnetic field. By Faraday’s law, a changing magnetic field induces an electric field that is modulated by the conductance of the earth. It is this field that drives power system GIC.
There are concerns that GIC and GMD events may adversely affect the equipment used in the transmission and distribution of electric power and in the electronic equipment used to protect and manage the power system operation. The source of entry for GIC is at grounding points on the power system. Solar storms also impact the communications networks used by the power system. The following explains how GIC affects the power system and provides recommended approaches to mitigate its impact.