Partially Decentralized Secondary Current Sharing and Voltage Restoration Controller Design for DC Microgrids With Event-Triggered Sampling

Decentralized control is a practical strategy to be employed for many reasons such as simplicity of design and easy implementation. In this paper, we design a partially decentralized secondary controller to achieve the objective of current sharing and DC bus voltage restoration in islanded direct-current (DC) microgrid (MG) systems. Compared to existing centralized or distributed control methods, only DC bus voltage information is required in local decentralized controller design, which greatly reduces the communication and implementation cost. On the other hand, such simplified design and implementation may limit the performances of the overall designed system. However, our rigorous theoretical analysis establishes that the proposed method is able to restore the DC bus voltage with bounded error by properly selecting control parameters. Furthermore, we also design an event-triggered sampling based decentralized controller and investigate its control performance, which indicates that the proposed event-triggered controller can ensure to achieve a uniformly bounded voltage restoration error but with much less signal communication cost. Finally, all these theoretical findings are supported by case studies conducted in a real-time DC MG test system built in OPAL RT.