A coordinated high-order sliding mode control of DFIG wind turbine for power optimization and grid synchronization

This paper aims to propose a coordinated high-order sliding mode control (HOSMC) method for power optimization and grid synchronization of a doubly-fed induction generator (DFIG) based wind energy conversion system (WECS). The super-twisting algorithm is employed to maximize the captured wind energy with optimal rotor speed tracking, and regulate the voltage to fulfill the grid requirement. Subsequently, a grid synchronization scheme is proposed, where the wind turbine stator terminal voltage is controlled to synchronize with the grid voltage without employing the current control loop. Meanwhile, a novel reaching law is employed to accelerate the reaching speed. Simulations are carried out to verify the effectiveness of the novel approach, where the first order sliding mode control and the proportional-integral control are considered for comparison. A stepwise wind speed scenario, a variable wind speed condition, and the scenario under parameter perturbations are included in the comparative study. The simulation results fully reveal the robustness, chattering free property and high tracking precision of the proposed method.