@inproceedings{18bad5145a054423a862f2defe8acf7c,

title = "Harmonic transfer-function model of three-phase synchronous reference frame PLL under unbalanced grid conditions",

abstract = "The synchronous reference frame (SRF) phase-locked loop (PLL) is widely used in three-phase grid-connected converter systems. For the balanced grid condition, the PLL can be linearized in the dq frame, and the derived small-signal model is linear time-invariant (LTI), which can be readily analyzed with classical control theories. However, in the unbalanced grid, the presence of the negative-sequence voltage leads to frequency-coupling dynamics in the SRF-PLL, which cannot be characterized by the dq-frame LTI model. This paper thus proposes a harmonic transfer-function model of the SRF-PLL under three-phase unbalanced grid conditions based on the linear time-periodic theory. It is found that the negative-sequence voltage can result in considerable phase error, which yields three time-periodic coefficients in the dynamic model of SRF-PLL. Simulations and experimental results corroborate the effectiveness of the model. The frequency-coupling effects are verified in the time domain and the frequency domain.",

keywords = "Harmonic transfer function, Linear time-periodic, PLL, Small-signal model, Synchronous reference frame, Unbalanced grid",

author = "Yicheng Liao and Xiongfei Wang and Xiaolong Yue and Hong Gong",

year = "2019",

month = mar,

doi = "10.1109/APEC.2019.8721842",

language = "English",

isbn = "978-1-5386-8331-6",

series = "IEEE Applied Power Electronics Conference and Exposition (APEC)",

publisher = "IEEE Press",

pages = "58--65",

booktitle = "Proceedings of the 34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019",

note = "34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019 ; Conference date: 17-03-2019 Through 21-03-2019",

}