Modeling and Stability Assessment of Single-Phase Grid Synchronization Techniques: Linear Time-Periodic versus Linear Time-Invariant Frameworks

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Abstract

The grid synchronization unit, which is often based on a frequency-locked loop (FLL) or a phase-locked loop (PLL), highly affects the power converter performance and stability, particularly under weak grid conditions. It implies that a careful stability assessment of grid synchronization techniques (GSTs) is of vital importance. This task is most often based on obtaining a linear time-invariant (LTI) model for the GST and applying standard stability tests to it. Another option is modeling and dynamics/stability assessment of GSTs in the linear time-periodic (LTP) framework, which has received a very little attention. In this letter, the procedure of deriving the LTP model for single-phase GSTs is first demonstrated. The accuracy of the LTP model in predicting the GST dynamic behavior and stability is then evaluated and compared with that of the LTI one. Two well-known single-phase GSTs, i.e., the second-order generalized integrator-based FLL (SOGI-FLL) and enhanced PLL (EPLL), are considered as the case studies.
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The grid synchronization unit, which is often based on a frequency-locked loop (FLL) or a phase-locked loop (PLL), highly affects the power converter performance and stability, particularly under weak grid conditions. It implies that a careful stability assessment of grid synchronization techniques (GSTs) is of vital importance. This task is most often based on obtaining a linear time-invariant (LTI) model for the GST and applying standard stability tests to it. Another option is modeling and dynamics/stability assessment of GSTs in the linear time-periodic (LTP) framework, which has received a very little attention. In this letter, the procedure of deriving the LTP model for single-phase GSTs is first demonstrated. The accuracy of the LTP model in predicting the GST dynamic behavior and stability is then evaluated and compared with that of the LTI one. Two well-known single-phase GSTs, i.e., the second-order generalized integrator-based FLL (SOGI-FLL) and enhanced PLL (EPLL), are considered as the case studies.
Original languageEnglish
Article number8357505
JournalIEEE Transactions on Power Electronics
Volume34
Issue number1
Pages (from-to)20-27
Number of pages8
ISSN0885-8993
DOI
Publication statusPublished - Jan 2019
Publication categoryResearch
Peer-reviewedYes

    Research areas

  • Frequency locked loop (FLL), Generalized inverse Nyquist stability criterion, Harmonic transfer function, Linear time-periodic (LTP) systems, Modeling, Phase-locked loop (PLL), Single-phase systems, Stability analysis, Synchronization
ID: 280107974