Single-phase consensus-based control for regulating voltage and sharing unbalanced currents in 3-wire isolated AC microgrids

Burgos-Mellado, Claudio; Llanos, Jacqueline; Espina, Enrique; Saez, Doris; Cardenas, Roberto; Sumner, Mark; Watson, Alan

Abstract

A distributed control strategy is proposed to share unbalanced currents in three-phase threewire isolated AC Microgrids (MGs). It is based on a novel approach where, rather than analysing the MG as a three-phase system, it is analysed as three single-phase subsystems. The proposal uses a modified single-phase Q - E droop scheme where two additional secondary control actions are introduced per phase. The first control action performs voltage regulation, while the second one achieves the sharing of negative sequence current components between the 3-legs power converters located in the MG. These secondary control actions are calculated online using a consensus-based distributed control scheme to share negative sequence current components, voltage regulation, and regulating the imbalance at the converters' output voltage to meet the IEEE power quality standards. The proposed methodology has the following advantages over other distributed control solutions, such as those based on the symmetrical components or those based on the Conservative Power Theory: (i) it achieves sharing of unbalanced currents, inducing smaller imbalances in the converters' output voltages than those of other methods, and (ii) the sharing of the unbalanced currents is simultaneously realised in both the sequence domain and the a-b-c domain. The latter is difficult to achieve using other solutions, as will be demonstrated in this work. Extensive experimental validation of the proposed distributed approach is provided using a laboratory-scale 3-wire MG.

Citation

Burgos-Mellado, C., Llanos, J., Espina, E., Saez, D., Cardenas, R., Sumner, M., & Watson, A. (2020). Single-phase consensus-based control for regulating voltage and sharing unbalanced currents in 3-wire isolated AC microgrids. IEEE Access, 8, 164882-164898. https://doi.org/10.1109/ACCESS.2020.3022488

• Journal Article Type: Article
• Acceptance Date: Aug 30, 2020
• Online Publication Date: Sep 7, 2020
• Publication Date: Sep 7, 2020
• Deposit Date: Sep 16, 2020
• Publicly Available Date: Sep 16, 2020
• Journal: IEEE Access
• Electronic ISSN: 2169-3536
• Publisher: Institute of Electrical and Electronics Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 8
• Pages: 164882-164898
• DOI: https://doi.org/10.1109/ACCESS.2020.3022488
• Keywords: Consensus algorithm , Distributed control , Microgrids , Unbalanced currents sharing
• Public URL: https://nottingham-repository.worktribe.com/output/4906857
• Publisher URL: https://ieeexplore-ieee-org.ezproxy.nottingham.ac.uk/document/9187613