Attack-Isolation-Based Resilient Control of Large-Scale Systems Against Collusive Attacks

This paper investigates the resilient stability problem of large-scale systems under covert attacks. Covert attacks are difficult to detect, and the collusion among attacks on different subsystems makes the problem more challenging. To address this issue, a two-stage fixed-time observer is introduced for each subsystem to make the covert attack be exposed to its neighboring subsystems. Based on this, an attack isolation algorithm is developed against non-collusive covert attacks, and the notion of r∗-isolability is introduced to provide a necessary and sufficient condition for the success of attack isolation under the algorithm. To deal with collusive covert attacks, another attack isolation algorithm is further designed, and the notion of (r,s)-isolability is used to provide a sufficient condition for the effectiveness of the algorithm. Based on the proposed attack isolation techniques, a control law is developed to ensure the resilient stability of the system. Finally, two numerical examples are given to illustrate the effectiveness of the theoretical results.