A Flying-Capacitor Modular Multilevel Inverter based Dynamic Voltage Restorer for Voltage Quality Improvement in Electrical Distribution Grids

This paper proposes the mitigation of grid voltagedisturbances using a Flying-Capacitor Modular Multilevel Inverter(FC-MMI) based DynamicVoltage Restorer (DVR) solution.Which regulates the injection of thecompensation voltage in series and synchronism with the gridduring the voltage disturbance events, the auxiliary capacitorvoltage, while controlling the FC-MMIoutput current. this paper presents a flying-capacitor modularmultilevel converter (FC-MMI) based on series-connectedsub-modules. The proposed FC-MMIcircuit is characterized by thecross connection of upper and lower arm middle taps through aflying capacitor in per phase leg. By properly controlling the ACcurrent flowing through the flying capacitor, the power balancebetween upper and lower arms is achieved, leading to very smallvoltage ripples on sub-module DC capacitors.thatthe proposed FC-MMIalong with the proposed controlmethod performs satisfactorily in dynamic and static state.This feature enables the structure to be used to compensate for the power quality of power distribution networks. Modified Phase Modified Pulse Width Modulation (MPSPWM)in the inverter is used to create the desired waveform. TheIn-Phase control method is selected to control the proposed DVR and use the synchronous reference frame (SRF) method to detect the network voltage fluctuations. To verify and validate the proposed DVR performance, simulations are carried out in the MATLAB / SIMULINK software environment, and the results indicate the optimal performance and desirability of the proposed DVR to compensate for the voltage sag, swell and flicker power distribution grids. Theoretical analysis and simulation results are given toshow the high performance of the proposed solution