Fully Actuated System-Based Modeling and Control of DC Microgrids With Inductive Tie Lines: A Predictive Strategy

The problem of voltage recovery (VR) and current sharing has been a hot concern in the field of dc microgrids (MGs). The effort of this article is to design a secondary controller based on a model that reflects the circuit and bottom-level control characteristics of dc MGs with resistive-inductive lines to accomplish the above regulation tasks. Specifically, this article first establishes a fully actuated model for the output current based on an integrated model of the MG, which is not only simple in form but also captures the dynamics of the actual power system. Then, based on the created physical principle model, a distributed optimal fully actuated (DOFA) secondary predictive control strategy with a dynamic compensator is proposed to achieve VR and accurate current sharing. The concern for the future state of the dc MG allows the proposed predictive control method to achieve better performance. In particular, the setting of variable weights in the cost function enhances the degree of freedom of secondary regulation. An analysis of the stability of the closed-loop dc MG system and the completion of the regulation tasks with the proposed control scheme is given. Finally, extensive tests are performed on a photovoltaic-and-battery-based dc MG with the MPPT controller to verify the effectiveness of the proposed controller.