Dynamic Modeling, Selection, and Placement of Mitigation Devices for HEMP/GMD Events

A high-altitude electromagnetic pulse (HEMP) or solar-geomagnetic disturbance (GMD) can drive low-frequency geomagnetically induced currents (GICs) that force large power transformers into saturation, distorting AC waveforms, increasing losses, and risking thermal damage. This paper develops dynamic models of large synthetic grids that capture the transient response to simulated HEMP insults, then applies multi-objective optimization to quantify the trade-off between mitigation-device type, placement, and resulting transformer saturation. The study shows that flux-blocking devices provide the steepest reduction in relative saturation for a given device count, and that incorporating cost weights enables analysis of trade-offs between competing mitigation technologies and deployment strategies.