DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

Publication: Research - peer-reviewJournal article

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Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced grid voltage conditions. A modular implementation method of the proposed control strategy is developed for the DFIG controller. Finally, experiments are presented to validate the theoretical analysis.
Original languageEnglish
JournalI E E E Transactions on Power Electronics
Publication dateJul 2013
Volume28
Issue7
Pages3206-3218
Number of pages13
ISSN0885-8993
DOIs
StatePublished

Keywords

  • Control analysis, dc-capacitor current, doubly fed induction generator (DFIG), resonant controller, unbalanced grid voltage

ID: 77466761