Nonlinear Control Operation of DFIG-Based WECS Incorporated With Machine Loss Reduction Scheme

This article presents a novel adaptive backstepping based nonlinear control scheme incorporated with machine loss reduction and parameter uncertainties for grid-connected doubly fed induction generator (DFIG) driven wind energy conversion system (WECS). The proposed nonlinear controller is developed to stabilize both the grid and rotor side current control loops of direct-drive DFIG-based WECS. Traditional feedback linearization controllers are sensitive to system parameter variations and disturbances on DFIG-based WECS, which demands advanced control techniques for stable and efficient performance considering the nonlinear system dynamics. The proposed nonlinear controller incorporates the system uncertainty and nonlinearities while ensuring the stability of the drive system through Lyapunov stability criteria. A machine loss reduction algorithm is also incorporated to achieve enhanced efficiency. The performance of the proposed nonlinear scheme is compared with conventional benchmark fixed gain proportional-integral control and sliding mode control scheme for the rotor-side converter controller. The proposed nonlinear controller for DFIG-based WECS integrated with machine loss reduction scheme is successfully implemented in real time using DSP board DS 1104 for a prototype 350 W DFIG. The simulation and experimental results prove the efficacy of the proposed scheme under variable operating conditions such as wind speed variation, grid voltage disturbances, and parameter uncertainties.