ISSN E 2409-2770
ISSN P 2521-2419

Grid Integration of Multistring Photovoltaic Plants with Modular Multilevel Converter

Vol. 5, Issue 2, PP. 16-20, February 2018


Keywords: Renewable integration, Modular Multilevel Converter, maximum power point tracking, MPPT, photovoltaic system

Download PDF

This paper presents the application of Modular Multilevel Converter (MMC) for connecting multistring photovoltaic generation plant. The proposed approach makes it possible for an increased PV plant capacity to be integrated with the grid, while also improving efficiency of conversion and power quality. To increase the efficiency of individual PV module, a DC-DC boost converter is employed with maximum power point tracking (MPPT). The MPPT is implemented by employing Perturb & Observe (P&O) algorithm. The PV modules with DC-DC boost converters are connected in parallel to form a DC bus which is connected to the utility grid with MMC. The MMC inverts the DC bus voltage for interfacing to the grid while maintaining the DC bus voltage constant.  The simulation of the overall system in Simulink/MATLAB verifies the validity of the proposed system. 

  1. Ahmad Kamal: Department of Electrical Energy Systems Engineering US-PCAS-E, UET Peshawar, Paksitan. (e-mail:
  2. Dr. Abdul Basit: Department of Electrical Energy Systems Engineering US-PCAS-E, UET Peshawar, Paksitan. (e-mail:

Ahmad Kamal Abdul Basit

  1. [1] A. M. T. O. A. S. A. P. W. a. M. A. G. Shafiullah, "Meeting energy demand and global warming by integrating renewable energy into the grid," in 2012 22nd Australasian Universities Power Engineering Conference (AUPEC), Bali, 2012.
  2. [2] European Photovoltaic Industry Association, "Global market outlook for photovoltaics 2013–2017," 2013.
  3. [3] J. K. P. a. F. B. S. B. Kjaer, "A review of single-phase grid-connected inverters for photovoltaic modules," IEEE Transactions on Industry Applications, vol. 41, no. 5, pp. 1292-1306, Oct. 2005.
  4. [4] M. M. a. G. Cramer, "Multi-String-Converter: The next step in Evolution of String-Converter Technology," in 9th European Conference on Power Electronics and Applications, Graz, Austria, Aug. 2001.
  5. [5] E. B.-M. M. A.-P. O. G.-B. Ana Cabrera-Tobar, "Review of advanced grid requirements for the integration of large scale photovoltaic power plants in the transmission system," Renewable and Sustainable Energy Reviews, vol. 62, pp. 971-987, Sep 2016.
  6. [6] J.-S. L. a. F. Z. P. J. Rodriguez, "Multilevel inverters: a survey of topologies, controls, and applications," IEEE Transactions on Industrial Electronics, vol. 49, no. 4, pp. 724-738, Aug. 2002.
  7. [7] M. C. a. V. G. Agelidis, "Multilevel converters for single-phase grid connected photovoltaic systems-an overview," in Industrial Electronics, 1998. Proceedings. ISIE ’98. IEEE International Symposium, Jul. 1998.
  8. [8] M. L. R. T. C. K. a. M. S. T. Kerekes, "Evaluation of Three-phase Transformerless Photovoltaic Inverter Topologies," IEEE Trans. Power Electronics, vol. 24, no. 9, pp. 2202-2211, Sep. 2009.
  9. [9] S. O. a. L. M. T. E. Ozdemir, "Fundamental-frequency-modulated Six-level Diode-clamped Multilevel Inverter for Three-phase Stand-alone Photovoltaic System," IEEE Trans. Industrial Electronics, vol. 56, no. 11, pp. 4407-4415, Nov. 2009.
  10. [10] P. C. J. R. a. M. P. E. Villanueva, "Control of a Single-phase Cascaded H-bridge Multilevel Inverter for Grid-connected Photovoltaic Systems," IEEE Trans. Industrial Electronics, vol. 56, no. 11, pp. 4399-4406, Nov. 2009.
  11. [11] A. M. E. V. P. C. B. W. a. J. R. S. Kouro, "Control of a cascaded h-bridge multilevel converter for grid connection of photovoltaic systems," in 35th Annual Conference of the IEEE Industrial Electronics Society (IECON09), Porto, Portugal, Nov. 2009.
  12. [12] S. B. J. R. S. K. a. R. L. M. A. Perez, "Circuit Topologies, Modeling, Control Schemes, and Applications of Modular Multilevel Converters," IEEE Transactions on Power Electronics, vol. 30, no. 1, pp. 4-17, Jan. 2015.
  13. [13] J. Q. B. B. M. S. a. P. B. S. Debnath, "Operation, Control, and Applications of the Modular Multilevel Converter: A Review," IEEE Transactions on Power Electronics, vol. 30, no. 1, pp. 37-53, Jan. 2015.