LCL-Filter Design for Robust Active Damping in Grid-Connected Converters

Rafael Pena-Alzola, Marco Liserre, Frede Blaabjerg, Martin Ordonez, Yongheng Yang

Research output: Contribution to journalJournal articleResearchpeer-review

126 Citations (Scopus)


Grid-connected converters employ LCL-filters, instead of simple inductors, because they allow lower inductances while reducing cost and size. Active damping, without dissipative elements, is preferred to passive damping for solving the associated stability problems. However, large variations in the grid inductance may compromise system stability, and this problem is more severe for parallel converters. This situation, typical of rural areas with solar and wind resources, calls for robust LCL-filter design. This paper proposes a design procedure with remarkable results under severe grid inductance variation. The procedure considers active damping using lead-lag network and capacitor current feedback. Passive damping is also discussed. The design flow, with little iteration and no complex algorithms, selects the proper ratios between the switching and resonance frequency, the grid and converter inductance, and the filter capacitance and total inductance. An estimation for the grid current total harmonic distortion (THD) is also proposed. Simulation and experiments validate the proposals.
Original languageEnglish
JournalI E E E Transactions on Industrial Informatics
Issue number4
Pages (from-to)2192-2203
Number of pages12
Publication statusPublished - Nov 2014


  • Active damping
  • LCL-filter
  • active damping
  • grid connected converter
  • grid-connected converter
  • robust design
  • stability
  • weak grid

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