Date Added: Apr 2012
The resilience of Supervisory Control And Data Acquisition (SCADA) systems for electric power networks for certain cyber-attacks is considered. In particular, the authors study the robustness of the observability properties of the network to the loss of some measurements. It was recently shown, under the full measurement assumption, that the problem can be cast as a generalization of the minimum cut problem involving costly nodes. In this paper, they show that it can be reformulated as a standard minimum cut problem (without costly nodes) on a modified graph of proportional size. An important consequence of this result is that the observability problem can be solved efficiently. Their approach provides the first exact efficient algorithm for this problem. It is illustrated on a numerical example.