Advanced Defense Strategy for Cyber-Resilient Frequency Control in Real Power Grids

This paper investigates the load frequency control problem of real power systems equipped with the automatic generation control service under false data injection (FDI) attacks. The available methods either require the exact system model or extensive historical data. Moreover, they cannot distinguish load changes from cyber-attacks. To address these challenges, this paper proposes a model-free defense method comprising an observer and a detector. The observer estimates the targeted signal and compares the difference between the estimated and observed signals as the state estimation error with a predetermined threshold value. When the state estimation error exceeds the threshold value, the detector detects an attack. In this situation, the observer’s output is the state estimation error. This causes the estimated signal to be sent to the secondary controller to mitigate the attack’s effect. If the state estimation error is smaller than the threshold value, no attack has occurred on the system. In such conditions, the observed signal is sent to the secondary controller. The proposed method rebuilds the actual system output in real-time under cyber-attacks. The presented method is independent of the system’s mathematical model and historical data, and it has a simple design procedure. This method can successfully distinguish load changes from FDI attacks. Moreover, it is not dependent on the size and complexity of the power system. The simulation results on the IEEE 14-bus and 39-bus power systems in the DIgSILENT PowerFactory show that the proposed method can timely detect the attacks and completely mitigate the effects of attacks on the system’s dynamic performance. Also, the obtained false alarm and attack detection rates are zero and over 98%, respectively.