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

  • ehsan Akbari Mazandaran University of Science and Technology
Keywords: Flying-Capacitor, DVR, Modular multilevel converter, MPSPWM switching, Voltage Quality


This paper proposes the mitigation of grid voltage disturbances using a flying-capacitor modular multilevel Inverter (FC-MMI) based dynamic voltage restorer (DVR) solution. Which regulates the injection of the compensation voltage in series and synchronism with the grid during the voltage disturbance events, the auxiliary capacitor voltage, while controlling the FC-MMI output current. this paper presents a flying-capacitor modular multilevel converter (FC-MMI) based on series-connected sub-modules. The proposed FC-MMI circuit is characterized by the cross connection of upper and lower arm middle taps through a flying capacitor in per phase leg. By properly controlling the AC current flowing through the flying capacitor, the power balance between upper and lower arms is achieved, leading to very small voltage ripples on sub-module DC capacitors . that the proposed FC-MMI along with the proposed control method 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. The  In-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 to show the high performance of the proposed solution.


[1] J.D. J.D. Barros and J.F. Silva, “Multilevel optimal predictive dynamic voltage restorer,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2747-2760, Aug. 2014.
[2] E. Akbari, A. Sheikholeslami and j. Rouhi, "operation DVR based Modular Multilevel Cascade Converter based on Double-star Chopper-cells (MMCC-DSCC) for Compensation Voltage sag and swell in Power Distribution Grids, Majlesi Journal of Mechatronic Systems (MJMS), Vol. 4, NO. 1, pp. 39-47, March 2015.
[3] A. Elnady and M. Salama, “Duall Role CDSC based Dual Vector Control for Effective Operation of DVR with Harmonic Mitigation” IEEE Transactions on Industrial Electronics, Vol. 16, No. 8, pp. 2614-2625, Nov 2017.
[4] S. Deband, B. Bahrani and B. Peter, "Operation, control and Applications of a Modular Multilevel Converter: A Review," IEEE Transactions on Industrial Electronics, vol. 30, no. 1, pp. 1237-1253, Aug 2016.
[5] K. Gupta and A. Ranjan, “Multilevel inverter topologies with reduced device count a review” IEEE Trans. Power Electron, Vol. 31, No. 1, pp. 234-247, July2017.
[6] P. Brendan and D. Holmes, “Natural Capacitor Voltage Balancing for a Flying Capacitor Converter Induction Motor Drive” IEEE Trans. Power. Electron, Vol. 24, No. 6, pp. 1554-1561, Jun 2009.
[7] M. Vasiladiotis and V. Rufer, "Accurate Capacitor Voltage Ripple Estimation and Current Control Considerations for Grid-Connected Modular Multilevel Converter," IEEE Transactions on Industrial Electronics, vol. 29, no. 9, pp. 4568-4579, May 2015.
[8] N. R. Zargari and B. Wu, "A Flying Capacitor Modular Multilevel Converter for Medium-Voltage Motor Drive," IEEE Trans. Power. Electron, vol. 28, no. 7, pp. 4821-4832, Jan 2018.
[9] A. M. Rauf and V. Khadkikar, "An Enhanced Voltage Sag Compensation Scheme for Dynamic Voltage Restorer," IEEE Transactions on Industrial Electronics, vol. 62, no. 5, pp. 2683-2692, May 2015.
[10] T. Bruck and G. Holmes, “Optimal pulse-width modulation for three-level inverter” IEEE Trans. Power. Electronic, vol. 20 no. 1., pp. 1528-1535, Feb. 2013.
How to Cite
Akbari, ehsan. (2020). A Flying-Capacitor Modular Multilevel Inverter based Dynamic Voltage Restorer for Voltage Quality Improvement in Electrical Distribution Grids. Majlesi Journal of Mechatronic Systems, 9(3). Retrieved from http://journals.iaumajlesi.ac.ir/ms/index/index.php/ms/article/view/438