A Multilevel Vulnerability Assessment Strategy of $N-k-\{j\}$ Contingencies for Ensuring the Cybersecurity of Power Systems

This paper proposes a reliable method for identifying vulnerable attack paths in a power system from the perspective of the system operator. The goal is to infer the potential disruption that can be caused by an attacker with single or multiple consecutive attacks under different loading scenarios. The assessment of damage is contingent upon the load disruption incurred and the system's attainment of a non-convergent state or the formation of an isolated island as a repercussion of the attack. The proposed method is a multilevel exploration task that identifies the most vulnerable lines in the system during each level. The method uses a two-step scheme, wherein Stage-1 identifies vulnerable lines using a novel multilevel vulnerability assessment index based on modal analysis and participation factors during $N-k-\{j\}$ outages, and Stage-2 recognizes the explored vulnerable attack path(s). The method is tested on the IEEE 14-bus system and proves to be effective in terms of both time efficiency and simplicity.