Sensor faults and actuator faults inevitably exist in DC microgrids due to device aging, environmental changes, or cyber-attacks, which seriously degrades control performance. The existing resilient control methods for DC microgrids still bear some deficiencies, such as poor performance, limited applicability, and heavy tasks of calculation or communication. To overcome these problems and to realize the resilient control for DC microgrids with both sensor faults and actuator faults, this article has proposed a decentralized control scheme to guarantee the control resilience of bus voltage regulation and current sharing simultaneously. The proposed scheme contains a residual-based fault detection logic to locate the faulty sensor, an adaptive fault estimation observer to estimate the system state and faults simultaneously, and a finite-time fault-tolerant control law to guarantee resilience to faults. The stability proof based on Lyapunov analysis is given to validate the effectiveness of the proposed scheme. Finally, a DC microgrid model is built in the hardware-in-the-loop testbed to validate the effectiveness and superiority of the proposed decentralized resilient control scheme.

Distributed control is widely applied in DC microgrids (MGs) for the cooperation of multiple distributed generations (DGs), but the inevitable communication delays between controllers will deteriorate the control performance including the steady-state and stability. In this paper, a unified distributed control approach based on PI consensus algorithm is proposed to achieve accurate weighted average voltage recovery and current proportional sharing with communication delays. Meanwhile, the scattering transformation is introduced to compensate for the adverse effect of heterogeneous communication delays on stability. It is proven that the DC MG is guaranteed to be stable with unbounded and heterogeneous communication delays by the Lyapunov stability criterion. Finally, the effectiveness and advantages of the proposed distributed control are verified via MATLAB/Simulink.

This paper investigates the resilient consensus control problems for distributed energy storage (DES) systems in DC microgrids (MGs) with false data injection attacks (FDIAs) in the communication channels. The existing resilient control methods still bear some deficiencies, such as poor performance, limited applicability, and heavy calculation. To overcome these problems and to realize the resilient control of bus voltage regulation and state of charge (SoC) balancing for DES systems in DC MG, this article has proposed a resilient consensus control scheme to guarantee resilience under unbounded FDIAs. The proposed scheme uses input-output feedback linearization to construct a second-order linear system for each DES node and utilizes the dual-layer communication architecture to establish the resilient observer. Compared with other model-based resilient control methods, the proposed scheme can effectively deal with unbounded FDIAs with lower costs in both communication and calculation. Then, the stability analysis based on the Lyapunov technique is given to prove the feasibility of the proposed scheme. Finally, the DC MG test model is built in MATLAB/Simulink to verify the efficiency of the proposed scheme.

The DC microgrid is connected to the AC utility by parallel bidirectional power converters (BPCs) to import/export large power, whose control directly affects the performance of the grid-connected DC microgrid. Much work has focused on the hierarchical control of the DC, AC, and hybrid microgrids, but little has considered the hierarchical control of multiple parallel BPCs that directly connect the DC microgrid to the AC utility. In this paper, we propose a hierarchical control for parallel BPCs of a grid-connected DC microgrid. To suppress the potential zero-sequence circulating current in the AC side among the parallel BPCs and realize feedback linearization of the voltage control, a d - q -0 control scheme instead of a conventional d - q control scheme is proposed in the inner current loop, and the square of the DC voltage is adopted in the inner voltage loop. DC side droop control is applied to realize DC current sharing among multiple BPCs at the primary control level, and this induces DC bus voltage deviation. The quantified relationship between the current sharing error and DC voltage deviation is derived, indicating that there is a trade-off between the DC voltage deviation and current sharing error. To eliminate the current sharing error and DC voltage deviation simultaneously, slope-adjusting and voltage-shifting approaches are adopted at the secondary control level. The proposed tertiary control realizes precise active and reactive power exchange through parallel BPCs for economical operation. The proposed hierarchical control is applied for parallel BPCs of a grid-connected DC microgrid and can operate coordinately with the control for controllable/uncontrollable distributional generation. The effectiveness of the proposed control method is verified by corresponding simulation tests based on Matlab/Simulink, and the performance of the hierarchical control is evaluated for practical applications.

In this paper, the robustness problem in adaptive iterative learning control for discrete-time nonlinear systems with time-iteration-varying parameters is investigated. The time-iteration-varying parameter can be expressed as the sum of an iteration-invariant time-varying part and a bounded iteration-drift term. Then a novel dead-zone method is applied in estimations of the iteration-invariant part and the drift bound simultaneously. The boundedness of tracking error is ensured by rigorous analysis. The efficacy of the proposed method is illustrated through simulation results.

The DC microgrid is connected to the utility by parallel bidirectional power converters (BPCs) to realize power exchange. This paper proposes a decentralized control method for BPCs of a grid-connected DC microgrid. The proposed control method consists of two parts, that is, the inner loop and the outer loop, and improves the performance of the system from the following three aspects. First, a d-q-0 three axis control strategy instead of the conventional d-q two axis control strategy is adopted to suppress the circulating current in the AC side generated by the parallel BPCs. Second, a feedback linearization control strategy based on the square of the DC voltage is adopted for the DC voltage control, which can make the control of the DC voltage linear and decoupled. Third, the decentralized DC droop control is adopted to realize the DC current sharing among the BPCs and to make the BPCs provide voltage support for the DC microgrid in coordination. The simulation confirms the effectiveness of the proposed control method.