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The Scientific World Journal
Volume 2014, Article ID 538520, 12 pages
Research Article

Improved Power Control Using Optimal Adjustable Coefficients for Three-Phase Photovoltaic Inverter under Unbalanced Grid Voltage

1State Key Laboratory of Power Transmission Equipment and System Safety and New Technology, Chongqing University, Chongqing 400044, China
2Department of Electrical Engineering, University of Wisconsin Milwaukee, Milwaukee, WI 53211, USA
3Guangdong Key Laboratory of Clean Energy Technology, South China University of Technology, Guangzhou 510640, China

Received 1 June 2014; Accepted 8 August 2014; Published 27 August 2014

Academic Editor: Hua Bai

Copyright © 2014 Qianggang Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Unbalanced grid faults will lead to several drawbacks in the output power quality of photovoltaic generation (PV) converters, such as power fluctuation, current amplitude swell, and a large quantity of harmonics. The aim of this paper is to propose a flexible AC current generation method by selecting coefficients to overcome these problems in an optimal way. Three coefficients are brought in to tune the output current reference within the required limits of the power quality (the current harmonic distortion, the AC current peak, the power fluctuation, and the DC voltage fluctuation). Through the optimization algorithm, the coefficients can be determined aiming to generate the minimum integrated amplitudes of the active and reactive power references with the constraints of the inverter current and DC voltage fluctuation. Dead-beat controller is utilized to track the optimal current reference in a short period. The method has been verified in PSCAD/EMTDC software.