Coordinated attacks on electric power systems in a cyber-physical environment

With increasing terrorism and sabotage activities, the power grid is becoming more vulnerable to various kinds of cyber and physical attacks. Coordination between the attacks could bring higher impacts on the power system, as evidenced by the 2015 Ukrainian power system cyberattack. There is limited study in existing literature about possible coordinated attack scenarios and the detailed mathematical modeling of them. To prevent future coordinated attacks against power systems, in this paper the cyber-physical security of the power system is analyzed and probable coordinated attack scenarios are proposed. Two typical attack coordination examples are studied in detail: the coordination between load redistribution (LR) attack and attacking generators; and the coordination between LR attack and attacking lines. They are formulated as bilevel optimization problems, where the attacker at the upper level aims to maximize the load curtailment while the defender at the lower level makes an effort to reduce the load curtailment. The case studies conducted based on a modified IEEE 14-bus system demonstrate the potential damaging effects of the coordinated attacks. And it is shown that coordinated attacks could cause higher load curtailment than the standalone attacks. This study can provide meaningful insights on how to prevent and mitigate such high-impact, low-frequency (HILF) coordinated attacks. (C) 2017 Elsevier B.V. All rights reserved.