An improved coordination control for a novel hybrid AC/DC microgrid architecture with combined energy storage system

Abstract

This paper proposes a novel hybrid ac/dc microgrid (MG) architecture that integrates a combined energy storage system (ESS) for both ac and dc subgrids, which avoids the problems associated with the distributed ESSs with different state-of-charges (SoCs). To realize effective operation of the hybrid MG, this paper has also proposed an improved coordination control strategy between the combined ESS and the paralleled bidirectional interlinking converters (BILCs). First, a novel SoC-based adaptive droop control is designed for the combined ESS to provide dc bus voltage support and ac bus frequency support, and the lifetime of the combined ESS is extended because the overcharge and overdischarge can be avoided. Second, ac bus frequency and dc bus voltage are regarded as global parameters to enforce the power interaction between ac and dc subgrids. The power interactions between ac and dc subgrids can be proportionally allocated with the coordination coefficients to avoid an over-used BILC. Furthermore, the proposed distributed coordinated power control (DCPC) for BILCs network has plug-and-play capacity and allows an acceptable communication time delay and communication link failures. Finally, the effectiveness of the proposed coordination control strategy applied into the novel hybrid ac/dc MG system is verified by the real-time hardware-in-loop (HIL) tests.