An Adaptive Digital-Control Scheme for Improved Active Power Filtering Under Distorted Grid Conditions

The operation of active power filters (APFs) under nonideal grid conditions, such as grid-frequency fluctuation and voltage harmonics, can lead to significant degradation in harmonic compensation performance. This paper proposes an adaptive digital-control scheme for a three-phase APF for use in har...

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Bibliographic Details
Published in:	IEEE transactions on industrial electronics (1982) Vol. 65; no. 2; pp. 988 - 999
Main Authors:	Hogan, Diarmaid John, Gonzalez-Espin, Francisco J., Hayes, John G., Lightbody, Gordon, Foley, Raymond
Format:	Journal Article
Language:	English
Published:	New York IEEE 01-02-2018 The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:	Active control Active filters Active power filter (APF) Adaptive control Adaptive filters Control systems Converters digital control Distortion Distributed generation Electric potential Emulators Frequency estimation Harmonic analysis Harmonics Phase locked loops Phase locked systems phase-locked loop (PLL) Power harmonic filters power quality Proportional integral resonant control Resonant frequency Variations
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Summary:	The operation of active power filters (APFs) under nonideal grid conditions, such as grid-frequency fluctuation and voltage harmonics, can lead to significant degradation in harmonic compensation performance. This paper proposes an adaptive digital-control scheme for a three-phase APF for use in harmonically distorted and variable-frequency grid conditions. This scheme is comprised of a grid-frequency adaptive resonant current controller and an enhanced synchronous-reference-frame phase-locked loop (SRF-PLL). The PLL uses an inherently stable adaptive-filtering stage to improve grid phase and frequency estimates in the presence of voltage harmonics. The improved PLL frequency estimate is used to update the resonant gains of a PI + vector-proportional-integral current-control scheme, implemented in the SRF. This enables the APF to maintain optimal performance in distorted grid conditions. The performance of the proposed APF control scheme is evaluated in a test microgrid, with a 15-kVA three-phase voltage-source converter configured as the APF, a 90-kVA grid emulator utilized to replicate distorted grid conditions, and a load emulator implemented to draw harmonic currents. The control scheme presented here is shown to demonstrate significant performance improvements under nonideal grid conditions compared with equivalent adaptive and nonadaptive methods.
ISSN:	0278-0046 1557-9948
DOI:	10.1109/TIE.2017.2726992