What Should We Know to Predict Geomagnetically Induced Currents in Power Transmission Lines?

This review considers several issues of space weather studies that are directly related to the problem of geomagnetically induced current (GIC) excitation in the power line transmission systems. Expectations to reduce the damage to technological systems from space weather were related with elaboration of models capable of real-time predictions of electromagnetic disturbances at the Earth's surface. However, the examination of the feasibility of the MHD simulation to predict the level of geomagnetic field variability, and consequently GICs, during the May 27–28, 2017 storm showed that the modeling reasonably well reproduced the global magnetospheric parameters, but the predicted magnetic field variability dB/dt has turned out to be more than order of magnitude less than that observed. The reason is the inability of current global MHD models to adequately predict the fine structure of the storm/substorm – Pi3 disturbances, and consequently GICs that they drive. Moreover, impulsive disturbances such as Pi3 pulsations demand a special tool for their analysis. Data processing technique for a 2D network of magnetic stations has to be elaborated to automatically recognize eddy current structures in the ionosphere and estimate their characteristics. The proposed technique applied to Pi3 pulsations on March 17, 2013 revealed that each vortex caused a disturbance of the vertical magnetic component Z and GIC burst up to ∼ 100A. The efficiency of GIC generation by different types of magnetic storms must be examined. For that it is necessary to compare GIC responses to storms caused by coronal mass ejection and by corotating interaction region, and to estimate the normalized GIC-effectiveness of each storm. The excitation rate of GIC during storms may be associated with the occurrence of mesoscale current vortices.