Dangerous Duet: Encountering Composite Cascading Failures in Cyber-Physical Systems

With fault propagation in both physical and cyber networks, composite cascading failures pose great challenges to Cyber-Physical Systems (CPS), such as smart grids. Due to the complex coupling between networks, and the distinct propagation rules of faults originated from different kinds of nodes, its time-varying impact on the CPS is yet to be uncovered, which is essential to resilient CPS design. To study this problem, we establish a generic composite cascading model that incorporates both load redistribution and cyber virus infections. By this model, we observe an interesting change in both short-term and longterm evolution behaviors compared to its simple counterpart. Moreover, we propose an iterative inference algorithm to analyze its transient impact. Given the snapshot of any initial condition, extensive simulations show that our algorithm predicts nodal failing probabilities and the expected surviving ratio of the system with a narrow error margin (5 % and 15 %, respectively) under various settings, outperforming the data-driven method based on GNN + RNN. With these information, effective prevention and control measures of composite cascading failures can be designed for CPS.