Four-leg converters with improved common current sharing and selective voltage-quality enhancement for islanded microgrids

Zhou, Xiao, Tang, Fen, Loh, Poh Chiang, Jin, Xinmin and Cao, Wenping (2016). Four-leg converters with improved common current sharing and selective voltage-quality enhancement for islanded microgrids. IEEE Transactions on Power Delivery, 31 (2), pp. 522-531.

Abstract

Four-leg dc-ac power converters are widely used for the power grids to manage grid voltage unbalance caused by the interconnection of single-phase or three-phase unbalanced loads. These converters can further be connected in parallel to increase the overall power rating. The control of these converters poses a particular challenge if they are placed far apart with no links between them (e.g., in islanded microgrids). This challenge is studied in this paper with each four-leg converter designed to have improved common current sharing and selective voltage-quality enhancement. The common current sharing, including zero sequence component, is necessary since loads are spread over the microgrid and they are hence the common responsibility of all converters. The voltage-quality enhancement consideration should however be more selective since different loads have different sensitivity levels towards voltage disturbances. Converters connected to the more sensitive load buses should therefore be selectively triggered for compensation when voltage unbalances at their protected buses exceed the predefined thresholds. The proposed scheme is therefore different from conventional centralized schemes protecting only a common bus. Simulation and experimental results obtained have verified the effectiveness of the proposed scheme when applied to a four-wire islanded microgrid.

Publication DOI: https://doi.org/10.1109/TPWRD.2015.2450111
Divisions: Engineering & Applied Sciences
Additional Information: © 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Uncontrolled Keywords: four-legconverter,microgrid,unbalance,virtual impedance,voltage quality
Full Text Link: http://ieeexplo ... rnumber=7134803
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Published Date: 2016-04
Authors: Zhou, Xiao
Tang, Fen
Loh, Poh Chiang
Jin, Xinmin
Cao, Wenping ( 0000-0002-8133-3020)

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Version: Accepted Version


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