A Novel Flexible Multiport Interlinking Converter for DC Microgrid Clusters

This article presents a multiport interlinking converter (MIC) for synergising the power flow in direct-current microgrid (DCMG) clusters. The proposed MIC integrates three-level neutral point clamped (NPC) modules with pluggable full-bridge modules. It enables the interconnection of DC subgrids at wide voltage levels, ranging from low to medium voltage. The proposed MIC adopts the multiple-transformer design which facilitates the decoupling of power flow among subgrids and plug-and-play operations in the DCMG cluster. Different operating modes of the MIC are thoroughly analysed. A global power sharing (GPS) strategy is devised for the MIC to proactively manage the power imbalance between power generation and consumption. It involves the intrinsic droop characteristics of each subgrid, enabling an optimised power profile of the DCMG cluster. The proposed MIC and its power control strategy are validated through hardware-in-the-loop (HIL) and experimental tests based on a 4-kW MIC prototype. The proposed MIC is designed to provide flexible tie interfaces for DCMG clusters to push the boundaries of their compatibility, flexibility, and interoperability.