Cyber-Attacks in the Automatic Generation Control

Power systems are traditionallymonitored and controlled by an IT infrastructure, referred to as Supervisory Control and Data Acquisition (SCADA) system. The cyber-physical interaction of power systems (physical) and SCADA systems (cyber) rises security issues, since the links between those systems are vulnerable to cyber-attacks that can potentially lead to catastrophic economical and societal effects. In this chapter we focus on a specific cyber-physical link, the Automatic Generation Control (AGC), which is an automatic frequency control loop closed over the SCADA system. We provide an impact analysis in case of a cyber-attack on the AGC signal. We first carry out a feasibility analysis based on reachability and optimal control theory, that provides an information regarding the existence of an attack pattern that can disturb the power system. We then deal with the problem of synthesizing an attack signal and treat it as a nonlinear control synthesis problem. Third, performance of our methodologies are illustrated by means of dynamic simulations on IEEE-118 bus network.