Mitigation of torsional vibrations in the drivetrain of DFIG-based grid-connected wind turbine

This paper presents a nonlinear technique based on the sliding mode control theory for mitigation of torsional vibrations in grid-connected doubly fed induction generator based wind turbines. The proposed method increases the lifespan of wind turbines by reducing torsional vibrations caused by mechanical or electrical events. The effectiveness of the proposed control scheme are demonstrated through simulation results of two case studies that evaluate impacts of (i) a voltage sag and (ii) a series capacitor switching in the transmission line on the drivetrain of a 750 kW wind turbine. The simulated model contains wind turbine aerodynamics, as well as dynamics of generator, multi-mass drivetrain, rotor- and grid-side converters, and transmission line with a series compensation capacitor.