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Recent events have shown that cyber attacks are becoming real threats to the power system reliability and resiliency, and there is no exception to the DC microgrids which would become popular in the future. Currently, most secondary controls in DC microgrids heavily rely on communications, making them specifically vulnerable to cyber attacks. This paper presents a resilient distributed control based on the average consensus algorithm and the proportional-integral (PI) consensus algorithm to enhance the system resilience against denial of service attacks and improve the microgrid stability, particularly in the presence of constant power loads. The proposed control casts the average voltage restoration problem into an optimization problem, and because of this, the voltage control is immune to the communication damage caused by malicious denial of service attacks. Moreover, the small-signal stability model of the DC microgrid with distributed energy storages and constant power loads is established, and the impacts of varying constant power loads, controller parameters and communication topology on the system stability are analyzed. Simulations are conducted to verify the effectiveness of the proposed method. • Global voltage and current regulations are realized by distributed mechanisms. • Distributed controllers can keep the DC microgrids stable during cyber-attacks. • Proportional-integral consensus based controllers can recover from Denial of Service attacks. • Distributed controllers contribute to improving stability in the presence of constant power loads. [ABSTRACT FROM AUTHOR]

Highlights • A virtual capacitor droop control (CDC) using fuzzy logic algorithm in multiple HESSs can adaptively adjust the droop coefficient, so as to eliminate the impact of the line impedance on the power splitting and improve the power sharing accuracy. This study has not been reported in previous work. • Both the small-signal model and eigenvalue analysis are presented to study the stability of the HESS system using CDC, investigate the impact of the droop coefficient variation on the system dynamics and determine an optimal range of the modified droop coefficient. This work has not been involved in the previous studies. Abstract In a DC microgrid, virtual capacitor droop control (CDC) can achieve power allocation according to different frequency characteristics of a hybrid energy storage system (HESS). However, the control performance may be easily affected by the line impedance. In this paper, an adaptive droop controller based on a fuzzy logic algorithm is proposed. By detecting the unbalanced power and the voltage deviation, the droop coefficient can be adaptively adjusted to mitigate the influence of the line impedance and achieve desirable power splitting in the HESS. Furthermore, the small-signal model of the HESS is established and the impact of the droop coefficient variation on the stability of the DC microgrid is exploited. The simulation results in PSCAD/EMTDC verify the effectiveness of the proposed adaptive droop controller. It has been proved that desirable power splitting can be obtained among multiple HESSs under different scenarios. [ABSTRACT FROM AUTHOR]