Coordinated Predictive Secondary Control for DC Microgrids Based on High-Order Fully Actuated System Approaches

Abstract

The problem of voltage recovery and current balancing has been a hot research topic in the field of DC microgrids. How to build a model that reflects the circuit and component-level control (e.g., inner control loops) characteristics and design a secondary controller based on it to accomplish the above output regulations is the concern of this paper. Accordingly, in this paper, based on the large-signal model of microgrids, the corresponding high-order fully actuated model is developed for DC microgrids, which is not only simple in form but also able to capture the details of the actual power system, such as the relationship between voltage and current. Further, a distributed predictive fully actuated secondary control strategy is proposed based on the developed model to achieve voltage recovery and accurate current sharing. Allowing one to design the secondary controller free from the constraints of physical coupling in the microgrid is one feature of this control strategy, while the other is the arbitrarily assignable closed-loop poles. An analytical model of the closed-loop DC microgrid system with predictive fully actuated secondary control is developed, and the analysis of stability and output current consensus is presented therewith. Extensive tests on a hardware system of a DC microgrid with solar panels and an MPPT controller are performed to validate the performance of the designed controller.