A Damping Control Strategy for Torsional Oscillations of DFIG-based WTs Caused by Inertia Control

As wind power plays an increasingly important role in power systems, the safe and steady operation of wind turbines is causing more attention. The torsional oscillation in doubly fed induction generation based (DFIG-based) wind turbines (WTs) is a serious problem reducing service life of mechanical component. However, as the grid codes require wind farms to participate in frequency response, the application of inertia control may make the issue more significant. This paper presents a damping control strategy for suppressing torsional oscillation of DFIG-based WTs' drive-train caused by the inertia control. Different from the existing damping control schemes, the proposed damping control is based on modulation of reactive current of grid-side converter. This kind of control scheme can effectively restrain torsional oscillation without increasing the complexity of torque control or speed control. Time-domain simulations are performed to demonstrate the efficacy of the proposed control scheme.