Security Measures for Grids against Rank-1 Undetectable Time-Synchronization Attacks

Time-synchronization attacks on phasor measurement units (PMUs) pose a real threat to smart grids; it was shown that they are feasible in practice and can have nonnegligible negative impact state estimation, without triggering the bad data detection mechanisms. Previous works identified vulnerability conditions when targeted PMUs measure single phasor. Yet, capable of measuring several quantities. We present novel general case, where any number phasors share same time reference. One is sufficient condition does not depend values. propose security requirement prevents provide greedy offline algorithm enforces it. If this satisfied, there still possibility grid be attacked, although we conjecture very unlikely. identify two necessary conditions, which For each, metric shows distance between observed conditions. recommend their monitoring for security. Numerical results IEEE-39 bus benchmark with load profiles show measurements satisfying our far from vulnerable.