Cyber Attack-Defense Analysis for Automatic Generation Control with Renewable Energy Sources

The advancements in the power grid due to integration of new technology arises concerns regarding its reliability in terms of performance and security. On one hand, the gradual shift towards renewable energy sources leads to rise in uncertainty in terms of control and demand satisfaction. On the other hand, the integration of communication devices in order to make the grid smart increases its vulnerability to malicious activity. Automatic Generation Control (AGC) which is needed to maintain the system frequency and inter-area exchange has an important place in both the concerns. This paper presents an attack-defense analysis on the AGC operation of the power grid under varying conditions of renewables. It has two main contributions. First, a cyber-attack is conducted on the AGC algorithm with various levels of renewable penetration, to analyze the effect of an attack with renewables. Then a new algorithm for AGC using a PID control based approach is used and the attack is repeated to evaluate the impact. Secondly, an algorithm for attack mitigation is designed and its performance is analyzed with both the AGC algorithms. The various factors considered are effectiveness in reducing the impact on the system and adverse effects on normal operations. The experiments were conducted using the PowerCyber CPS security testbed at Iowa State University.