UIO-based Cyber Attack Detection and Mitagation Scheme for Load Frequency Control System

Cyber attack affects the frequency regulation of load frequency control (LFC) system, which could cause instability in power systems. In this paper, false data injection (FDI) attacks for tie- line power measurements are specifically studied, and a novel attack detection and mitigation scheme is proposed to reduce the harm caused by it. First, we design an unknown input observer (UIO) to estimate the true value of tie-line power. Then, a signal credibility function is designed to detect attacks. The signal credibility function is based on the numerical difference and the slope difference between the estimated signal and the measured signal. We detect the attack by comparing the evaluation function of the signal with the evaluating indicator. Finally, the purpose of attack mitigation is achieved by replacing the measured value with the estimated value of the tie line power. From the simulation results of a multi-area LFC control system, the effectiveness of the proposed scheme is demonstrated.