A Distributed Projection Operator-Based Unknown Input Observer for Attack Estimation and Mitigation on DC Microgrids

Cyberattacks on transmitted signals are the most critical threats to modern microgrid (MG) systems and should be accurately addressed to ensure safe and reliable operation. This article investigates the cybersecurity of dc MGs against false data injection attacks and develops a novel model-based observer system. The proposed projection operator (PO)-based unknown input observer is uniquely designed to detect attacks on the transmitted data from other distributed generation units. For this purpose, a bank of PO observers is developed in each distributed generation unit to estimate all neighbor units' dynamic states. Cyberattack reconstruction compares the remotely observed state values with the measured ones. Afterwards, the detected attack signal values are utilized to restore the integrity of the compromised signals, effectively mitigating the harmful effects of cyberattacks. The most important feature of this scheme, which distinguishes it from similar methods, is that there is no need for a secure channel or additional information transfer in this method. Extensive real-time numerical simulations are performed to assess the practicality and efficiency of the proposed approach when subjected to various attack scenarios, demonstrating its advantages over other methods.