Geomagnetically Induced Currents in Ethiopia Power Grid: Calculation and Analysis.

Accurately defining the level of geomagnetically induced currents (GICs) in a power grid is an important process in evaluating the effects of magnetic storm disturbance on a power grid. With the full-node model presented in this paper, the long-term effects of geomagnetic disturbances on the 400-230-kV power grid in Ethiopia are calculated. Two parameters, namely, GICMax-H and GICMax-L (high- and low-probability extreme values), which are the bases of the risk assessment of the GIC, are proposed. The differences and the interaction of the GIC between the 230- and 400-kV power grids in November 9-11, 2004, are presented. The results expose that the probability of a high-risk GIC value in the low-latitude region can still be significant. The low-voltage system should be included when modeling and assessing the GIC in the high-voltage system. In Ethiopia, the GIC values in the northwest, southeast, and central regions are larger, and the 400-kV substations, such as S1, S2, S8, S10, and S48, and the 230-kV substations, such as S42, S43, S17, S16, and S53, should be intensively monitored when the effect of the GIC is evaluated. All the results can enrich the knowledge on the GIC in the low-latitude region and provide some assistance to assess the geomagnetic storm disasters.