Stochastic Defense Against Complex Grid Attacks

We describe stochastic defense mechanisms designed to detect sophisticated grid attacks involving both physical actions (including load modification) and sensor output alteration. The initial attacks are undetectable under a full ac power-flow model even assuming ubiquitous sensor placement, while hiding large line overloads. The defensive techniques apply network control actions that change voltages in a random fashion and additionally introduce (random) low-rank corrections to covariance matrices.