Second-order sliding mode control for DFIG-based wind turbines fault ride-through capability enhancement

Area of Science:

• Electrical Engineering
• Renewable Energy Systems
• Control Theory

Background:

• Doubly Fed Induction Generators (DFIGs) are crucial for wind power integration.
• Grid codes mandate fault ride-through (FRT) capability for wind turbines.
• Traditional sliding mode control (SMC) faces challenges like chattering.

Purpose of the Study:

• To evaluate the fault ride-through (FRT) capability of DFIG-based wind turbines.
• To propose and analyze a high-order sliding mode (HOSM) control strategy for enhanced FRT.
• To address the chattering issue inherent in classical SMC.

Main Methods:

• Implementation of a second-order sliding mode (SOSM) control.
• Utilizing NREL's FAST simulation code for a 1.5-MW DFIG wind turbine model.
• Simulating grid faults including frequency variations and unbalanced voltage sags.

Main Results:

• The proposed HOSM control demonstrates robust performance against grid disturbances.
• Chattering-free operation was achieved, minimizing mechanical stress on the wind turbine drivetrain.
• Effective ride-through capability was validated under various fault scenarios.

Conclusions:

• High-order sliding mode control offers a superior solution for DFIG fault ride-through.
• The chattering-free nature of HOSM is advantageous for wind turbine longevity and grid integration.
• This control strategy enhances the reliability and stability of wind power generation.