Enhanced Hybrid MMC Integration into DC Microgrid for low voltage application

The Modular Multilevel Converter (MMC) is a promising converter utilised in HVDC (High Voltage Direct Current) systems. MMC has numerous advantages over other converters, such as modular structure, output voltage and current scalability, superior power quality, and no required filter. Despite these benefits, it is less appealing for small-scale systems like Microgrid because of the many submodules (SMs). This work explores the integration of hybrid MMC into a DC Microgrid comprising various renewable and storage devices. Hybrid MMC consisting of half and full bridge SMs is driven using the proposed modified Nearest level modulation (MNLM) scheme, which enhances output levels to 3Nhalf+3Nfull+1 (Nhalf / Nfull is number of half / full bridge SMs) compared to conventional NLM, which generates N+1 levels. Thus, with MNLM applied to hybrid MMC, we get improved power quality, lower system cost, and require fewer SMs. Initially, the system is modelled and tested in MATLAB Simulink to acquire the offline simulation results. Subsequently, the real-time simulation is performed with the help of a hardware-in-loop simulation setup, which comprises an FPGA-based NI PXIe and Compact RIO for experimental verification of the proposed scheme.