A Novel Observer Design for Disturbance and Attack-Tolerance State Estimation in Microgrids

The growing prevalence of cyber-threats poses significant security concerns for microgrid (MG) operations, creating an urgent need for effective attack mitigation strategies. Traditional state estimation techniques using observers offer potential solutions, however, considering the sensor measurements can be susceptible to cyber-attacks, they are only effective when external disturbances, such as grid voltage fluctuations and load variations, are either absent or known. When these disturbances are unknown, they can introduce significant estimation errors, compromising mitigation efforts. To address this challenge, this paper proposes a novel disturbance- and attack-tolerant state estimation approach using a set of unknown input observers (UIOs). The proposed design methodology ensures error-free estimation of MG voltages and currents under both unknown disturbances and cyber-attack conditions. Furthermore, to demonstrate its effectiveness, the feasibility of the proposed estimation approach, the stability of observer-integrated microgrids, and its robustness to parameter variations due to capacitor and inductor degradation are thoroughly analyzed and evaluated through theoretical analysis. The overall performance of the proposed estimation methods is further validated by real-time implementation on a dSPACE-based microgrid control platform.