Robust Active Disturbance Rejection Control for LVRT capability enhancement of DFIG-based wind turbines

This article presents the development of a strategy to enhance the Low-Voltage Ride-Through capability (LVRT) of Doubly Fed Induction Generator (DFIG)-based Wind Turbines (WTs). The developed control scheme proposes a trajectory generation system and a high-performance rotor current controller. First, the rotor current trajectories are obtained according to the grid codes requirements. These codes introduce suitable values for the electromagnetic torque and the active and reactive power during operation in normal and fault modes. A detailed analysis of controllability and stability aims to find out how to pair the control inputs and the controlled outputs according to the suggested operation conditions. As a result, a comprehensive study of the required rotor current trajectories to enhance the LVRT capability is developed. Second, the design of the rotor current controller is based on Active Disturbance Rejection Control (ADRC) approach. This controller accomplishes two main objectives: (1) it guarantees a robust tracking of the proposed trajectories, despite uncertainties, disturbances and symmetrical and asymmetrical faults in the grid; and (2) it keeps the rotor voltages and currents in their allowed ratings. Finally, the proposed scheme and the theoretical analysis are validated with simulation studies and laboratory tests.