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Abstract
Gridconnected power converters should employ advanced current controllers, e.g., Proportional Resonant (PR) and Repetitive Controllers (RC), in order to produce highquality feedin currents that are required to be synchronized with the grid. The synchronization is actually to detect the instantaneous grid information (e.g., frequency and phase of the grid voltage) for the current control, which is commonly performed by a PhaseLockedLoop (PLL) system. Hence, harmonics and deviations in the estimated frequency by the PLL could lead to current tracking performance degradation, especially for the periodic signal controllers (e.g., PR and RC) with a fixed sampling rate. In this paper, the impacts of frequency deviations induced by the PLL and/or the grid disturbances on the selected current controllers are investigated by analyzing the frequency adaptability of these current controllers. Subsequently, strategies to enhance the frequency adaptability of the current controllers are proposed for the power converters to produce high quality feedin currents even in the presence of grid frequency deviations. Specifically, by feeding back the PLL estimated frequency to update the center frequencies of the resonant controllers and by approximating the fractional delay using a Lagrange interpolating polynomial for the RC, respectively, the frequencyvariationimmunity of these periodic current controllers with a fixed sampling rate is improved. Experiments on a singlephase gridconnected system are presented, which have verified the discussions and the effectiveness of the frequency adaptive current controllers.
Original language  English 

Journal  IEEE Transactions on Power Electronics 
Volume  31 
Issue number  10 
Pages (fromto)  7273  7285 
Number of pages  13 
ISSN  08858993 
DOIs  
Publication status  Published  Oct 2016 
Keywords
 Frequency adaptive
 Frequency variations
 Resonant controller (RES)
 Repetitive controller (RC)
 Fractional order filter
 Lagrange interpolating polynomial
 Gridconnected power converters
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 1 Finished

PV2GRID: A NextGeneration Grid Side Converter with Advanced Control and Power Quality Capabilities
Blaabjerg, F., Yang, Y. & Sangwongwanich, A.
01/01/2015 → 30/09/2017
Project: Research