Decentralized Control for Parallel Bidirectional Power Converters of a Grid-Connected DC Microgrid

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-O 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.