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.


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