  Geomagnetic disturbances and E3 high-altitude electromagnetic pulse events
pose a substantial threat to the electrical grid by adversely impacting and
damaging high-voltage transmission networks and equipment. To evaluate the
risks and mitigate the potential effects of these hazards, this work proposes
PowerModelsGMD.jl (abbr. PMsGMD). PMsGMD is an open-source Julia package that
solves for quasi-dc line flow and ac power flow problems in a system subjected
to geomagnetically induced currents. Unlike commercially available software
solutions, it is extensible and applicable to a variety of problems. The
flexibility of this framework is demonstrated by applying it to the problem of
identifying mitigation strategies via line switching for a time-extended
transformer heating problem. An overview of PMsGMD is presented in this paper:
introduction to its design, validation of its implementation, demonstration of
its performance and effectiveness, and a description of how it may be applied
to aid system-operation decisions.
