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Due to the unbalanced load connection in the sensitive load bus (SLB), the ac microgrid may suffer from voltage unbalance in the system. To overcome this issue, this article presents a new distributed control scheme to achieve the unbalanced voltage compensation for islanded ac microgrid with limited noncontinuous communication among the distributed generation (DG) units. In this article, a two-layer control framework, including the cyber layer and the primary control layer, is employed. The proposed control strategy that is applied in the cyber layer implements an event-triggered communication to effectively compensate for the unbalanced voltage in the SLB. In contrast with the centralized control strategy, the proposed control strategy is fully distributed, and the information exchange among the DG units at only the event-triggered times. As a result, the communication burdens can be measurably reduced while the control performance is not affected. The stability is analyzed with the Lyapunov function in this article. Finally, several experimental case studies are provided to verify the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

This article presents a reduced-order generalized proportional-integral observer based resonant super-twisting sliding mode controller (RST-SMC) for the three-phase ac–dc converters. On the contrary to utilizing the proportional-integral controller in regulating the dc-link voltage, which may cause large undershoot/overshoot under the disturbance, the proposed voltage control strategy for the dc-link has high disturbance rejection ability and the settling time has been greatly reduced. In addition, the proposed RST-SMC in the current control loop not only preserve the merits of the sliding mode controller but also achieve the current tracking without steady-state error in the stationary αβ frame. The effectiveness of the proposed method has been verified by a lab-constructed experimental prototype. [ABSTRACT FROM AUTHOR]

This study proposes a decentralized coordination control scheme for series-connected H-bridge rectifiers. Each rectifier module is controlled as a voltage-controlled source by a local controller, which needs only individual information. The local controller is composed of an active power-frequency (P-ω) control and a fixed voltage amplitude control. Compared to the conventional methods based multi-level phase-shifting modulation where centralized controller is needed, the proposed control strategy allows indefinite modular expansion without increasing the computational load of the local controller. Therefore, it has decreased cost and increased scalability. The synchronization mechanism of series modules is analyzed and the stability of the system is proved. The feasibility of the proposed strategy is verified by experimental results. [ABSTRACT FROM AUTHOR]