Cooperative control strategy for voltage restoration and power allocation in DC microgrids

Abstract

This paper proposes a novel cooperative control strategy for voltage restoration and power management in DC microgrids based on the DC bus signaling (DBS) method. In the conventional DBS method, the operation mode is determined according to the voltage deviation. Thus, it is difficult to achieve voltage restoration. To overcome this problem, the conventional DBS method is modified by applying the total power of dispatchable units (DUs) to identify the operation mode instead of the voltage deviation. As a result, the average output voltage of the DUs is restored to its nominal value in all of the operation modes without difficulty. In addition, accurate power sharing is achieved regardless of the line impedance or load change by regulating the voltage magnitude using a simple PI controller. Furthermore, the control performance is theoretically analyzed using a small signal analysis to evaluate the stability of system. The proposed method is validated with results from a lab scale experiment.

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Acknowledgements

This work was supported in part by the NRF of Korea Grant under Grant NRF-2018R1D1A1A09081779 and in part by the KETEP and the MOTIE under Grant 20194030202310.

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Correspondence to Hong-Hee Lee.

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Nguyen, D., Lee, H. Cooperative control strategy for voltage restoration and power allocation in DC microgrids. J. Power Electron. 20, 1025–1036 (2020). https://doi.org/10.1007/s43236-020-00101-y

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Keywords

  • DC bus signaling
  • Dispatchable unit
  • Droop control
  • Constant power load