Distributed Secondary Control for State of Charge Balancing with Virtual Impedance Adjustment in a DC Microgrid

Daner Hu, Yonggang Peng, Wei Wei and Yalong Hu
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Daner Hu: College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China
Yonggang Peng: College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China
Wei Wei: College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China
Yalong Hu: College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China

Energies, 2020, vol. 13, issue 2, 1-18

Abstract: For the purpose of accurate power sharing and the state of charge (SOC) balancing of each energy storage unit (ESU), a novel secondary control scheme which regulates the virtual impedance is proposed herein. However, there is a coupling relationship between the power sharing and voltage restoration process. In this study, the secondary control scheme could eliminate that effect so that the virtual impedance was only influenced by the system distribution and no longer affected by system initialization and noise. The proposed secondary strategy contains four controllers, including the current sharing controller, the SOC balancing controller, the virtual impedance correction controller, and the local reference voltage controller. Through the proposed scheme, the ESU with a higher SOC will give more power, whereas the lower one will give less power. The steady-state analysis for the uniqueness of the droop coefficient is given. Besides, the small-signal analysis of the ESU was thereby performed to ensure stability. Finally, the effectiveness of the proposed strategy was verified through MATLAB/Simulink.

Keywords: SOC balance; distributed control; virtual impedance; power sharing (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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