Distributed Sliding Mode Observer-Based Secondary Control for DC Microgrids Under Cyber-Attacks

The conventional distributed secondary control is widely adopted for distributed energy resources (DERs) in DC microgrids to achieve bus voltage restorations and output current/power sharing. However, when the DER systems are under cyber-attacks, the control variables of the conventional distributed secondary control will deviate from the nominal parameters and the stability of entire DC microgrids may not be guaranteed anymore. To this end, a distributed sliding mode observer (DSMO)-based secondary control is proposed in this paper. Based on local and neighboring measurements, the DSMO initially detects the false signals. Then, the estimated false signals are compensated by the control variables of the secondary control to eliminate the adverse impact. The stability of DSMO is verified by the convergence of the state variables. Both simulation and experimental results have validated that the proposed DSMO-based secondary control can effectively regulate the DER systems to track the bus voltage references and the desired output current/power under various types of cyber-attacks.