Stress testing power grids for cascades due to combined cyber and physical attacks

Due to the growing deployment of weakly protected Internet-of-Things devices connected to power grids, the probability and possible magnitude of cyber-induced load-altering attacks increases. At the same time, cascading failures in power grids can amplify the effect of a few initial line failures such that large blackouts occur. This paper aims to quantify the possible loss of load realizable by an omniscient adversary using combined load-altering and line interdiction attacks, exploiting cascading processes and accounting for system operators’ possible remedial actions. The resulting multi-stage bilevel optimization problem is transformed into a tractable single-level problem that can be solved by common MILP-solvers. Two case studies for the WSC C 9-Bus and IEEE RTS 24-Bus systems reveal that even N-1 secure system operation is not sufficient to avoid loss of load under potential load-altering attacks and that ignoring cascades underestimates the potential impact of such attacks.