A Novel Power Sharing Scheme of Controlling Parallel-Operated Inverters in Islanded Microgrids

Virtual impedances are often used in droop-controlled paralleled-voltage-sourced inverters (VSIs) to achieve proper power sharing. However, different and unknown output impedances of VSIs will affect the power decoupling and power sharing performances. To solve this problem, this article proposes a...

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Bibliographic Details
Published in:IEEE journal of emerging and selected topics in power electronics 2021-10, Vol.9 (5), p.5732-5746
Main Authors: Cao, Wenyuan, Han, Minxiao, Zhang, Xiahui, Xie, Wenqiang, Agundis-Tinajero, Gibran D., Guerrero, Josep M.
Format: Article
Language:English
Subjects:
Compensators
Decoupling
Design parameters
Design techniques
Distributed generation
Disturbance observer (DOB)
Disturbance observers
Electric potential
feed-forward control
Frequency control
Frequency deviation
Global Positioning System
Impedance
Inverters
Microgrids
Reactive power
Sensors
Synchronism
Synchronization
synchronization control
Systems stability
virtual complex impedance
Voltage
Voltage control
voltage-sourced inverters (VSIs)
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Summary:Virtual impedances are often used in droop-controlled paralleled-voltage-sourced inverters (VSIs) to achieve proper power sharing. However, different and unknown output impedances of VSIs will affect the power decoupling and power sharing performances. To solve this problem, this article proposes a novel controller for VSIs by using a disturbance observer (DOB). The DOB is adopted to observe the output currents of VSIs without any extra current sensors. On the one hand, the observed currents are fed forward to the output of voltage compensators, thereby the output impedances of VSIs are eliminated. On the other hand, the observed currents are introduced into the virtual complex impedance loops, which not only reconstruct the impedances of VSIs but also realize the proper power sharing. Besides, to improve the reactive power sharing accuracy, a synchronization control is proposed to strictly synchronize the VSIs only by using local measurements. Each VSI operates at a constant frequency, so the inherent frequency deviation of the traditional droop control is eliminated. A universal parameter design method is also presented based on the detailed discussion of system stability and voltage quality. Finally, simulation and experimental results clearly validate the proposed control scheme and the parameter design method.
ISSN:2168-6777
2168-6785
DOI:10.1109/JESTPE.2020.3048522