Study on Wide DC Voltage Output Characteristics of Submodule Hybrid MMC Converter

With the great development of renewable energy power generation technology, the flexible direct current transmission technology (VSC-HVDC) comes into being with the advantages of no commutation failure and low harmonics. At present, with the development of power electronics technology, modular multilevel converter (MMC) has become the preferred converter topology for flexible HVDC systems. Among them, the hybrid MMC system based on half-bridge submodule and full-bridge submodule has the advantages of fewer components and low switching loss on the basis of the self-clearing ability of DC short-circuit fault. Therefore, this paper analyzes the DC voltage output capacity of hybrid sub-module MMC, analyzes the mechanism of the wide DC voltage output of hybrid MMC system, and further adds the restriction conditions to the DC side voltage output range of hybrid MMC in combination with the balance requirements of the capacitance voltage stability of the half-bridge sub-module in the actual operation process. Finally, the simulation model and physical model are established respectively based on MATLAB/Simulink software and DSP+ FPGA platform.