  We propose a new heuristic approach for solving the challenge of determining
optimal placements for geomagnetically induced current blocking devices on
electrical grids. Traditionally, these determinations are approached by
formulating the problem as mixed-integer nonlinear programming models and
solving them using optimization solvers based on the spatial branch-and-bound
algorithm.However, computing an optimal solution using the solvers often
demands substantial computational time due to their inability to leverage the
inherent problem structure. Therefore, in this work we propose a new heuristic
approach based on a three-block alternating direction method of multipliers
algorithm, and we compare it with an existing stochastic learning algorithm.
Both heuristics exploit the structure of the problem of interest. We test these
heuristic approaches through extensive numerical experiments conducted on the
EPRI-21 and UIUC-150 test systems. The outcomes showcase the superior
performance of our methodologies in terms of both solution quality and
computational speed when compared with conventional solvers.
