Robust active damping in LCL-filter based medium-voltage parallel grid-inverters for wind turbines

Rafael Pena-Alzola, Javier Roldan Perez, Emilio Bueno, Francisco Huerta, David Campos-Gaona, Marco Liserre GAE, Graeme M. Burt

Research output: Contribution to journalArticle

13 Citations (Scopus)
156 Downloads (Pure)

Abstract

LCL-filter based grid-tie inverters require damping for current-loop stability. There are only software modifications in active damping, whereas resistors are added in passive damping. Although passive damping incurs in additional losses, it is widely used because of its simplicity. This article considers the active damping in medium-voltage parallel inverters for wind turbines. Due to cost reasons, only minimal software changes are allowed and no extra sensors can be used. The procedure must be robust against line-inductance variations in weak grids. Double-update mode is needed so the resonance frequency is under the Nyquist limit. The bandwidth reduction when using active damping is also required to be known beforehand. Moreover, the design procedure should be simple without requiring numerous trial-and-error iterations. In spite of the abundant literature, the options are limited under these circumstances. Filter-based solutions are appropriate and a new procedure for tuning the notch-filter is proposed. However, this procedure requires that the resistance of the inductors is known and a novel filter-based solution is proposed that uses lag-filters. The lag-filters displace the phase angle at the resonance frequency so that the Nyquist stability criterion is fulfilled. Simulations and experiments with a 100 kVA prototype validate the analysis.

Original languageEnglish
Number of pages12
JournalIEEE Transactions on Power Electronics
Early online date2 Feb 2018
DOIs
Publication statusE-pub ahead of print - 2 Feb 2018

Keywords

  • active damping
  • bandwidth
  • capacitors
  • damping
  • grid-tie inverter
  • inductance
  • inductors
  • inverters
  • lag-filter
  • LCL-filter
  • line-inductance
  • medium-voltage
  • notchfilter
  • resistors
  • voltage source converter

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