Abstract
With the widely application of the DC microgrid (MG), the utilization of renewable resources is improved by interconnecting nearby DC MGs. Since MGs are connected by different line impedances, the intuitive tradeoff exists between the conflicting goals of current sharing and voltage regulation in the conventional droop control scheme. A hierarchical control structure with a dynamic droop coefficient correction control (DCCC) is presented to achieve better power sharing in DC MGs. In the proposed hierarchical control scheme, the droop coefficient correction method is employed in the primary level, which corrects the droop coefficient automatically and the proportional current has been shared. Moreover, the droop coefficient of each converter is also dynamically adjusted to deal with the impact of uncertain line impedances. The robustness of performance to system uncertainties is also demonstrated. Meanwhile, the different current ratio of the microgrids can be provided to the DC bus by using the tertiary control level, which achieves an arbitrary power sharing among the microgrids. In addition, a small-signal model is developed to investigate the effects of coupling relationship in the control parameters in the voltage loop, voltage restoration controller and droop coefficients. Finally, the experimental results are presented to evaluate the effectiveness of droop coefficient correction control approach and hierarchical control scheme for the DC MG under resistive and constant power load (CPL) conditions.
Original language | English |
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Article number | 107277 |
Journal | International Journal of Electrical Power and Energy Systems |
Volume | 133 |
ISSN | 0142-0615 |
DOIs | |
Publication status | Published - Dec 2021 |
Bibliographical note
Funding Information:This work was supported by National Natural Science Foundation of China under grant No. 51977026 .
Publisher Copyright:
© 2021 Elsevier Ltd
Keywords
- DC MG
- Droop coefficient correction
- Hierarchical control
- Power sharing
- Small-signal model
- Voltage restoration