Optimal blocker placement for mitigating the effects of geomagnetic induced currents using branch and cut algorithm

Geomagnetic Disturbances (GMDs) currently introduce great threats to power grids worldwide. The geomagnetic induced currents (GICs) introduced by GMDs can damage transformers and increase the reactive power consumption which may further lead to power system instability. In order to find the best way to protect power grids, optimal blocker placement (OBP) is studied in this paper to minimize the damage of GICs. The OBP problem is formulated as a mix integer nonlinear programming problem. A global optimization solver, branch and cut method, is used to solve the OBP problem by taking advantage of its special structure. The effectiveness and optimality of our method is demonstrated on a 6-bus system, a 20-bus system and a much larger realistically sized system. Our method can provide optimal solution to OBP problems and can also be used to solve variations of OBP problems with different objective functions.