Power Flow Study of Low-Voltage DC Micro-Grid and Control of Energy Storage System in the Grid

  • Kim, Dong-Eok (KEPCO Research Institute, Korea Electric Power Corporation)
  • Received : 2016.06.08
  • Accepted : 2016.12.28
  • Published : 2017.03.01


DC distribution has several differences compared to AC distribution. DC distribution has a higher efficiency than AC distribution when distributing electricity at the same voltage level. Accordingly, power can be transferred further with low-voltage DC. In addition, power flow in a DC grid system is produced by only a voltage difference in magnitude. Owing to these differences, operation of a DC grid system significantly differs from that of an AC system. In this paper, the power flow problem in a bipolar-type DC grid with unbalanced load conditions is organized and solved. Control strategy of energy storage system on a slow time scale with power references obtained by solving an optimization problem regarding the DC grid is then proposed. The proposed strategy is verified with computer simulations.


DC micro-grid;Bipolar-type DC distribution;DC power flow;Energy storage system


  1. S. Backhaus, G. W. Swift, S. Chatzivasileiadis, W. Tschudi, S. Glover, M. Starke, J. Wang, M. Yue, and D. Hammerstrom "DC Microgrids Scoping Study: Estimate of Technical and Economic Benefits (March 2015)," US Department of Energy, 2015. [Online]. Available:
  2. P. Savage, R. R. Nordhaus, and S. P. Jamieson, "DC Microgrids: Benefits and Barriers," From Silos to Systems: Issues in Clean Energy and Climate Change, pp. 51-66, 2010.
  3. A.T. Ghareeb, A.A. Mohamed, and O.A. Mohammed, "DC microgrids and distribution systems: An overview," Power and Energy Society General Meeting (PES), IEEE, 2013, pp. 1-5.
  4. K. Hirose, T. Tanaka, T. Babasaki, S. Person, O. Foucault, B. J. Sonnenberg, and M. Szpek, "Grounding concept considerations and recommendations for 400VDC distribution system," Telecommunications Energy Conf. (INTELEC), IEEE, 2011, pp. 1-8.
  5. M. Noritake, K. Yuasa, T. Takeda, H. Hoshi, and K. Hirose, "Demonstrative research on DC microgrids for office buildings," Telecommunications Energy Conf. (INTELEC), IEEE, 2014, pp. 1-5.
  6. P. Nuutinen, T. Kaipia, P. Peltoniemi, A. Lana, A. Pinomaa, P. Salonen, J. Partanen, J. Lohjala, and M. Matikainen, "Experiences from use of an LVDC system in public electricity distribution," Electricity Distribution (CIRED), 2013, pp. 1-4.
  7. H. Kakigano, Y. Miura, T. Ise, and R. Uchida, "DC micro-grid for super high quality distribution - system configuration and control of distributed generations and energy storage devices," Power Electronics Specialists Conf. (PESC), IEEE, 2006, pp. 1-7.
  8. S. Whaite, B. Grainger, and A. Kwasinski, "Power quality in DC power distribution systems and microgrids," Energies, vol. 8, no. 5, pp. 4378-4399, 2015.
  9. D. Palit and A. Chaurey, "Off-grid rural electrification experiences from South Asia: Status and best practices," Energy for Sustainable Development, vol. 15, no. 13, pp. 266-276, Sept. 2011.
  10. T. Mishimaa, I. Taniguchib, H. Tamakic, Y. Kitagawad, K. Yutanie, and K. Suekanef, "A verify-cation of high-efficiency DC micro-grid power systems with high-performance power converters and energy management strategy," Procedia Technology, vol. 18, pp. 47-52, Sept. 2014.
  11. C. Abbey, D. Cornforth, N. Hatziargyriou, K. Hirose, A. Kwasinski, E, Kyriakides, G. Platt, L. Reyes, S. Suryanarayanan, "Powering through the storm: microgrids operation for more efficient disaster recovery," IEEE Power and Energy Magazine, vol. 12, no. 3, pp. 67-76, 2014.
  12. J. J. Justoa, F. Mwasilua, J. Leeb, J.-W. Jung, "ACmicrogrids versus DC-microgrids with distributed energy resources: A review," Renewable and Sustainable Energy Reviews, vol. 24, pp. 387-405, Aug. 2013.
  13. H. Kakigano, Y. Miura, and T. Ise, "Low-voltage bipolar-type DC micro-grid for super high quality distribution," IEEE Trans. on Power Electrons., vol. 25, no. 12, pp. 3066-3075, Dec. 2010.
  14. B. Liu, F. Zhuo, Y. Zhu, and H. Yi, "System operation and energy management of a renewable energy-based DC micro-grid for high penetration depth application," IEEE Trans. on Smart Grid, vol. 6, no. 3, pp. 1147-1155, May 2015.
  15. N. Eghtedarpour and E. Farjah, "Distributed charge/discharge control of energy storates in a renewableenergy-based DC micro-grid," IET Renewable Power Gen., vol. 8, no. 1, pp. 45-57, Jan. 2014.
  16. S.-y. Lu, L. Wang, T.-M. Lo, and A. V. Prokhorov, "Integration of wind power and wave power generation systems using a DC microgrid," IEEE Trans. on Ind. Applicat., vol. 51, no. 4, July/Aug. 2015.
  17. C. L DeMarco, C. A. Baone, Y. Han, and B. Lesieutre, "Primary and secondary control for high penetration renewables," PSERC Publication, May 2012. [Online]. Available:
  18. A. R. Bergen and V. Vittal, 'Power systems analysis' (Prentice-Hall Press., 1986, 2nd edn. 2000)
  19. M. Grant and S. Boyd: CVX - MATLAB software for disciplined convex programming, version 2.0 beta., Sept. 2013.
  20. D.-E. Kim, and M. A. El-Sharkawi "Dynamic equivalent model of wind power plant using an aggregation technique," IEEE Trans. on Energy Conv., vol. 30, no. 4, pp. 1639-1649, Dec. 2015.