Research of optimized sorting algorithm of capacitor voltage for MMC

The paper researched primary cause of increasing of switching frequency of modular multilevel converter led by traditional capacitor voltage sorting algorithm according to operation principle of the converter. It proposed an improved sorting algorithm of capacitor voltage in order to decrease the switching frequency and improve system running efficiency. The algorithm optimizes and improves the traditional sorting algorithm, gives three voltage references, and compares switched capacitor voltage in sub-module with the references, so as to judge whether the switched sub-module is going to keep running in the next time. It constructed a MMC simulation model contained 60 sub-modules with the optimized algorithm in Matlab. The simulation results verify that the optimized algorithm can significantly reduce switching frequency of power devices, and decrease power consumption of the converter.