Decentralized Bidirectional Voltage Supporting Control for Multi-Mode Hybrid AC/DC Microgrid

Abstract

A hybrid ac/dc microgrid consists of alternating current (ac) subgrid(s), direct current (dc) subgrid(s) and intermediate bidirectional power converters (BPCs). The presence of dc distribution networks complicates the operation and corresponding control of the hybrid ac/dc microgrid. This paper proposes a decentralized bidirectional voltage supporting control scheme for the multi-mode hybrid ac/dc microgrid, which can provide uninterruptable ac and dc voltages in case of unintentional ac and dc islanding events. An ac phase angle – dc voltage inverse droop control with virtual impedance are designed and implemented in BPCs, which can support the ac and dc voltages and enable seamless mode switching without additional voltage sources. Proper power sharing between ac and dc subgrids is realized without frequency deviation in the ac islanded mode. The stability of proposed control is analyzed under different modes, and its performance is verified by real-time hardware-in-loop (HIL) tests.