Analysis and Control of Single Phase Grid Connected Modular Multilevel Converter in Per Unit

Abstract

In this paper, a mathematical model and control methods of a modular multilevel converter are examined in per unit. Some control algorithms, like a sorting algorithm, circulating current control, proportional resonant controller and pulse width modulation techniques which are applicable on this converter are investigated. The average value model is used in per unit for the converter and it is combined with circulating current control method and propotional resonant current controller to suppress the second harmonic component in the circulating current. The effect of the circulating current harmonics on the resonance frequency is investigated. A Matlab/Simulink model is prepared for the simulation of converter modeled on the approach of the average value model and the results are generated from the simulation and they are discussed.