  False data injection (FDI) cyber-attacks on power systems can be prevented by
strategically selecting and protecting a sufficiently large measurement subset,
which, however, requires adequate cyber-defense resources for measurement
protection. With any given cyber-defense resource, this paper proposes a
preventive-corrective cyber-defense strategy, which minimizes the FDI
attack-induced region in a preventive manner, followed by maximizing the
cybersecurity margin in a corrective manner. First, this paper proposes a
preventive cyber-defense strategy that minimizes the volume of the FDI
attack-induced region via preventive allocation of any given measurement
protection resource. Particularly, a sufficient condition for constructing the
FDI unattackable lines is proposed, indicating that the FDI cyber-attack could
be locally rather than globally prevented. Then, given a non-empty FDI
attack-induced region, this paper proposes a corrective cyber-defense strategy
that maximizes the cybersecurity margin, leading to a trade-off between the
safest-but-expensive operation point (i.e., Euclidean Chebyshev center) and the
cheapest-but-dangerous operation point. Simulation results on a modified IEEE
14 bus system verify the effectiveness and cost-effectiveness of the proposed
preventive-corrective cyber-defense strategy.
