R. Rezaeipour  , A. Kazemi  , 
    Review of Novel Control Strategies for UPQC,
    International Journal of Electrical and Power Engineering,
    Volume 2,Issue 4,
    2008,
    Pages 241-247,
    ISSN 1990-7958,
    ijepe.2008.241.247,
    (https://makhillpublications.co/view-article.php?doi=ijepe.2008.241.247)
    Abstract: Active filters have been known as the best tools for harmonic mitigation as well as reactive power compensation. They were developed since 1983, when one of the first prototypes based on instantaneous power theory was reported. Many configurations such as shunt, series, hybrid (a combination of shunt and series active filters) and unified power quality conditioner (UPQC, a combination of series and shunt active filters) have been introduced and improved. With the emergence of fast computing devices, control strategies for UPQC are continually changing aiming at near perfect compensation. Considerable attention is paid to the reference voltage/current estimation and control strategies. In this study, several techniques are discussed and compared in terms of performance and implementation.
    Keywords: Power quality;active power filter;harmonic compensation;UPQC;control strategy;voltage control;current control