Computing GIC in large power systems

Geomagnetic induced current (GIC) phenomena are reviewed. A modeling approach in which the complex geomagnetic disturbance phenomenon is divided into three submodels is described. They are an ionospheric current source model, a geological (earth resistivity) model, and a power system model. The ionospheric and earth resistivity models are used in a finite element program to compute the earth surface potential any given substation. The GIC model of the power system is created by using the existing AC load flow and short circuit models. A new method for estimating GIC in the entire power system has been developed. A limited number GIC measurements for a given solar disturbance condition are combined with precomputed GIC for different assumed solar disturbance conditions. The accuracy of this method has been demonstrated.<
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