Distributed Optimal Control of DC Microgrid Considering Balance of Charge State

State-of-charge (SoC) imbalance and bus voltage deviation are two of the main problems in autonomous dc microgrids. Based on this concern, this paper presents an improved dual-quadrant SoC weighted control strategy and a distributed optimization control method to achieve SoC balance, ensuring accura...

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Bibliographic Details
Published in:IEEE transactions on energy conversion Vol. 37; no. 3; pp. 2162 - 2174
Main Authors: Huang, Bonan, Zheng, Shun, Wang, Rui, Wang, Huan, Xiao, Jiangfang, Wang, Peng
Format: Journal Article
Language:English
Published: New York IEEE 01.09.2022
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
accurate power-sharing
Batteries
Communication networks
Control methods
Control systems design
Dc microgrid
Delay effects
Delays
Deviation
Distributed generation
distributed optimization control
Electric potential
Energy storage
energy storage system
Independent variables
Microgrids
Optimal control
Optimization
Robust control
SoC balance
State of charge
Storage units
Voltage
Voltage control
voltage restoration
ISSN:0885-8969, 1558-0059
Online Access:Get full text
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Summary:State-of-charge (SoC) imbalance and bus voltage deviation are two of the main problems in autonomous dc microgrids. Based on this concern, this paper presents an improved dual-quadrant SoC weighted control strategy and a distributed optimization control method to achieve SoC balance, ensuring accurate power-sharing and bus voltage recovery. Firstly, this paper couples the injected/released power with the current SoC and observed average SoC value to weight the droop coefficient, which is based on the charge/discharge mode for the energy storage system. Then a secondary controller is designed based on distributed optimal control to eliminate the bus voltage deviation caused by the line impedance difference. The proposed optimal control method optimizes the average bus voltage to the nominal value and achieve accurate power-sharing by constructing the correlated variables and voltage independent intermediate variables exchanged among bulk energy storage units (ESUs). Since the voltage observer cannot accurately observe the true average bus voltage under the communication delay, the proposed distributed optimal control method without the voltage observer can ensure that the average bus voltage is optimized to the nominal value, thus improving the robustness of the control system. Finally, the correctness and effectiveness of the proposed method are verified in Simulink/MATLAB.
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ISSN:0885-8969
1558-0059
DOI:10.1109/TEC.2022.3169462