Résumé
For power grid congestion management, lots of research have focused on using generation redispatching, load shedding or demand side management flexibilities. However, a less costly option would be grid topology reconfiguration. Branch switching has been previously explored, since it could be formulated as a linear programming optimization problem we can solve, and showed some benefits. This can further be extended to the broader class of non-linear nodal reconfigurations at substations. In this paper, we present an expert system to automatically discover such topological remedial actions on congested grid states. It comes with a new adapted grid representation, conditional to the congestions of interest, which can be interpreted by operators. To test our expert system, we independently run it on thousands of realistic congested French grid states from 2012 to 2014 with a remedial action discovery success rate of 75\% Our exploration is quite efficient, since it is limited to single substation topological action and is usually successful on first try, even in the case of overloads above 30%.