Stability Analysis and Improvement of the Capacitor Current Active Damping of the LCL Filters in Grid-Connected Applications


Vol. 16, No. 4, pp. 1565-1577, Jul. 2016
10.6113/JPE.2016.16.4.1565


PDF    

 Abstract

For grid-connected LCL-filtered inverters, dual-loop current control with an inner-loop active damping (AD) based on capacitor current feedback is generally used for the sake of current quality. However, existing studies on capacitor current feedback AD with a control delay do not reveal the mathematical relation among the dual-loop stability, capacitor current feedback factor, delay time and LCL parameters. The robustness was not investigated through mathematical derivations. Thus, this paper aims to provide a systematic study of dual-loop current control in a digitally-controlled inverter. At first, the stable region of the inner-loop AD is derived. Then, the dual-loop stability and robustness are analyzed by mathematical derivations when the inner-loop AD is stable and unstable. Robust design principles for the inner-loop AD feedback factor and the outer-loop current controller are derived. Most importantly, ensuring the stability of the inner-loop AD is critical for achieving high robustness against a large grid impedance. Then, several improved approaches are proposed and synthesized. The limitations and benefits of all of the approaches are identified to help engineers apply capacitor current feedback AD in practice.


 Statistics
Show / Hide Statistics

Cumulative Counts from September 30th, 2019
Multiple requests among the same browser session are counted as one view. If you mouse over a chart, the values of data points will be shown.



Cite this article

[IEEE Style]

J. Xu, S. Xie, B. Zhang, "Stability Analysis and Improvement of the Capacitor Current Active Damping of the LCL Filters in Grid-Connected Applications," Journal of Power Electronics, vol. 16, no. 4, pp. 1565-1577, 2016. DOI: 10.6113/JPE.2016.16.4.1565.

[ACM Style]

Jinming Xu, Shaojun Xie, and Binfeng Zhang. 2016. Stability Analysis and Improvement of the Capacitor Current Active Damping of the LCL Filters in Grid-Connected Applications. Journal of Power Electronics, 16, 4, (2016), 1565-1577. DOI: 10.6113/JPE.2016.16.4.1565.