An LQR Controller for Damping of Subsynchronous Interaction in DFIG-Based Wind Farms

Mohsen Ghafouri, Ulas Karaagac, Houshang Karimi, Simon Jensen, Jean Mahseredjian, Sherif O. Faried

Research output: Journal article publicationJournal articleAcademic researchpeer-review

60 Citations (Scopus)


This paper presents a linear-quadratic regulator (LQR) for damping of subsynchronous interaction (SSI) in doubly-fed induction generator (DFIG)-based wind farms. The proposed LQR controller employs a full-state observer to estimate all state variables. The output of the LQR is added to control signals of inner current control loops of DFIG converters as supplementary control signals. The supplementary control signals are dynamically limited to avoid saturating the converters and to provide the DFIG with the desired transient response against power system faults. The proposed SSI damping controller is designed for a realistic series compensated wind farm, and its performance is verified using electromagnetic transient (EMT) simulations. The EMT simulations are performed using a detailed DFIG model which includes all nonlinearities and all required transient functions to meet the grid code requirements corresponding to fault-ride-through (FRT). The results show that the proposed SSI controller is able to significantly mitigate the oscillations due to the SSI phenomenon, and to provide excellent transient response against systems faults.
Original languageEnglish
Article number7857840
Pages (from-to)4934-4942
Number of pages9
JournalIEEE Transactions on Power Systems
Issue number6
Publication statusPublished - 1 Nov 2017


  • Doubly-fed induction generator (DFIG)
  • observer design
  • optimal control
  • series capacitor compensation
  • subsynchronous interaction (SSI)
  • wind farm

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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