Current balancing control for multi-port hybrid AC/DC microgrid

摘要

In this paper, a two-stage hybrid AC/DC microgrid with two DC outputs and one AC output is proposed to reduce the cost of power electronics devices. However, mismatched DC powers in these DC networks can cause the current sharing errors of active bridge (DAB) DC/DC converter and the unbalanced three-phase line current of AC/DC interfacing converter. To overcome these limitations, this paper proposes an enhanced two-stage based compensation strategy. First, a DC current sharing error compensation method is adopted to reduce the current sharing errors among the parallel-connected DAB converters for each DC subsystem. Second, the three-phase line current balancing control method through injecting zero-sequence voltage vector in the cascaded H-bridge based grid-interfacing AC/DC converter is used to reduce the three-phase line current imbalanced component. By using these proposed control schemes simultaneously, proper power sharing and power control can be realized in a complex multi-port hybrid AC/DC microgrid. Simulation results are provided to verify the correctness of the proposed methods.