Title
Optimized Controller Design for -Type Grid-Connected Inverter to Achieve High Robustness Against Grid-Impedance Variation
Abstract
Capacitor-current-feedback active damping is an effective method to suppress the LCL-filter resonance in grid-connected inverters. However, due to the variation of grid impedance, the LCL-filter resonance frequency will vary in a wide range, which challenges the design of the capacitor-current-feedback coefficient. Moreover, if the resonance frequency is equal to one-sixth of the sampling frequency (fs/6), the digitally controlled LCL-type grid-connected inverter can be hardly stable no matter how much the capacitor-current-feedback coefficient is. In this paper, the optimal design of the capacitor-current-feedback coefficient is presented to deal with the wide-range variation of grid impedance. First, the gain margin requirements for system stability are derived under various resonance frequencies. By evaluating the effect of grid impedance on gain margins, an optimal capacitor-current-feedback coefficient is obtained. With this feedback coefficient, stable operations will be retained for all resonance frequencies except (fs/6). Second, in order to improve system stability for a resonance frequency of (fs/6), a phase-lag compensation for the loop gain is proposed. Finally, a 6-kW prototype is tested to verify the proposed design procedure.
Year
DOI
Venue
2015
10.1109/TIE.2014.2341584
Industrial Electronics, IEEE Transactions  
Keywords
DocType
Volume
compensation,control system synthesis,damping,digital control,optimal control,power filters,power grids,power system interconnection,power system stability,resonant invertors,LCL-filter resonance frequency variation,LCL-filter resonance suppression,capacitor-current-feedback active damping,digital controlled LCL-type grid connected inverter,gain margin requirements,grid impedance variation,loop gain,optimal capacitor-current-feedback coefficient,optimized controller design,phase lag compensation,power 6 kW,sampling frequency,system stability improvement,$LCL$ filter,Active damping,grid impedance,grid-connected inverter,phase-lag compensation
Journal
62
Issue
ISSN
Citations 
3
0278-0046
3
PageRank 
References 
Authors
0.72
0
4
Name
Order
Citations
PageRank
Donghua Pan1235.53
Xinbo Ruan240776.53
Chenlei Bao330.72
Weiwei Li4121.79