Sliding mode control for DFIG grid-side converter based on extended state observer

Abstract

Aiming at the problem of poor control effect of grid-side converter of doubly-fed induction generator due to load change and filter parameter perturbation, a double closed-loop control strategy of grid-side converter based on extended state observer (ESO) and sliding mode control is proposed. The inner loop adopts ESO-based sliding mode direct power control with power as the state variable, and the outer loop adopts ESO-based sliding mode control with voltage square as the state variable. Using ESO to estimate the system state variables and lumped uncertainties including unmodeled dynamics, load variation and filter parameter perturbation of the system, the sliding mode control method can be designed without the accurate mathematical model of the system to realize the robust control of grid-side converter in a complex environment. In addition, the power difference feedforward link is introduced to reduce the impact of the nonlinearity of the outer loop sliding mode control when the load changes. Finally, two examples of load charge and filter parameter perturbation are simulated, and the results show that the proposed control strategy has stronger robustness in the complex environment than traditional vector control and sliding mode control.

Keywords

• doubly-fed induction generator
• grid-side converter
• extended state observer (eso)
• sliding mode control
• direct power control
• power difference feedforward
• double closed loop