Abstract
The stealthy attack, as a strategically designed false data injection attack against the power system state estimation mechanism, is able to let the corrupted measurements bypass residue-based bad data detectors with the same probability as that of uncorrupted measurements and is able to fool the system operator with the deviated estimates. While most of the existing articles assume the network topology to be fixed, the effects of switching topologies on such an attack are shown in this paper. A new mechanism is proposed to eliminate the possibility of such an attack via strategically shutting down some preselected transmission lines by turns and therefore switching the network topologies. The necessary and sufficient condition to achieve such elimination and the general form of possible attacks when the elimination is impossible are both formulated. The case where the attack is only stealthy in a subset of the preselected topologies is also studied. The general form of the possible estimate deviations caused by this "partially" stealthy attack is derived. Simulations and case studies are provided using different IEEE bus systems to show the efficiency of the proposed strategy, to discuss the countermeasures in the case when there always exist possible stealthy attacks, and to show how the possible deviations introduced by a "partially" stealthy attack could be affected by the decisions made by both the attacker and the system operator.