Improved Frequency Locked Loop Based Synchronization Method for Three-Phase Grid-Connected Inverter under Unbalanced and Distorted Grid Conditions

Wenjie Ma, Sen Ouyang and Weidong Xu
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Wenjie Ma: Department of Electric Power, South China University of Technology, Guangzhou 510640, China
Sen Ouyang: Department of Electric Power, South China University of Technology, Guangzhou 510640, China
Weidong Xu: Department of Electric Power, South China University of Technology, Guangzhou 510640, China

Energies, 2019, vol. 12, issue 6, 1-18

Abstract: To quickly and accurately estimate the parameters of the fundamental positive- and negative-sequence under the unbalanced and distorted grid voltage, a synchronization method is presented in this paper. The proposed method is based on both a harmonic decoupling network consisting of multiple dual second-order generalized integrators (MDSOGIs) and an improved frequency locked loop (IFLL), so it is called the MDSOGI-IFLL. Due to the IFLL, the system has the feature that the dynamic performance of estimating the fundamental frequency is independent of the variation of both the fundamental positive- and negative-sequence voltage. In this paper, a first-order linear frequency adaption model is established for the design of the IFLL. Finally, the good performance of the proposed MDSOGI-IFLL is validated by the simulation and experiment.

Keywords: frequency locked loop (FLL); synchronization method; unbalanced and distorted grid voltage; grid-connected inverter (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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