H∞ mixed‐sensitivity robust control design for damping low‐frequency oscillations with DFIG wind power generation.

This study presents a H∞ mixed‐sensitivity robust control design to improve the overall damping performance of low‐frequency oscillations for power systems with doubly fed induction generator‐based (DFIG) wind power generation. The supplementary damping controller is designed in the linear matrix inequality framework which allows the placement of the closed‐loop poles inside a pre‐defined region for improved stability. The damping signal is implemented at the reactive power modulation of the rotor‐side converter of the DFIG wind turbine (DFIG‐WT). The damping contribution of the power oscillator damper is compared with that provided by the power system stabiliser (PSS) of the synchronous generator (SG). State‐space system analysis and time‐domain simulations show the capability of DFIG‐WT to enhance the overall damping of the oscillatory modes even if PSSs are not installed at SG s. Also, the designed controller shows a robust performance to wind speed variations. The performance evaluation is based on the revised two‐area four machines system and the revised New England 39‐bus system. [ABSTRACT FROM AUTHOR]