State-space control for LCL filters: Comparison between the converter and grid current measurements

F. M. Mahafugur Rahman, Jarno Kukkola, Ville Pirsto, Mikko Routimo, Marko Hinkkanen

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This paper deals with discrete-time state-space current control of converters equipped with an LCL filter. Either the converter or grid current is measured and the unknown states are estimated using a reduced-order observer. These two current measurement options are compared by means of analysis and experiments under strong and weak grid conditions. To provide the basis for the comparison, equal reference-tracking performance is designed for both cases under strong grid conditions. In weak grids, the converter current measurement provides faster reference tracking, faster disturbance rejection, and better resonance damping in the case of the studied system where the LCL-filter resonance frequency is below the critical frequency.
Original languageEnglish
Title of host publicationProceedings of the 11th IEEE Energy Conversion Congress and Exposition, ECCE 2019
Number of pages8
ISBN (Electronic)978-1-7281-0395-2
Publication statusPublished - 29 Sept 2019
MoE publication typeA4 Conference publication
EventIEEE Energy Conversion Congress and Exposition - Baltimore, United States
Duration: 29 Sept 20193 Oct 2019
Conference number: 11

Publication series

NameIEEE Energy Conversion Congress and Exposition
ISSN (Print)2329-3721
ISSN (Electronic)2329-3748


ConferenceIEEE Energy Conversion Congress and Exposition
Abbreviated titleECCE
Country/TerritoryUnited States


  • Grid converter
  • LCL filter
  • Reduced-order observer
  • State-space current control
  • Weak grid


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