Robustness of Asymmetric Cyber-Physical Power Systems Against Cyber Attacks

In this paper, we propose a realistic model to investigate the cascading failure process in a cyber-physical power system (CPPS) which can be topologically modeled as an interdependent system consisting of a power network and a cyber-network. To evaluate the robustness of CPPS against cyber-attacks, we take into consideration the effects of computer malware spreading, power redistribution and overloading, and the interdependency between the coupled networks, and then adopt the stochastic failure model to calculate the time interval between the initial cyber-attack and a given level of power loss. We conduct a critical node analysis on the power network to identify the important buses whose removals are likely to trigger a serious blackout. Based on the results of the critical node analysis, we propose both deterministic and stochastic coupling strategies for an asymmetric CPPS with two subnetworks with unequal sizes, to improve its robustness against both random and intentional cyber-attacks. The simulation results on CPPSs built on IEEE 118 Bus and 300 Bus power systems indicate that the proposed coupling methods can effectively improve the system robustness against cyber-attacks.