Certainty equivalence-based robust sliding mode control strategy and its application to uncertain PMSG-WECS.

Area of Science:

• Renewable Energy Systems
• Control Theory
• Electrical Engineering

Background:

• Wind Energy Conversion Systems (WECS) are crucial for renewable energy, but are susceptible to uncertainties and disturbances.
• Permanent Magnet Synchronous Generators (PMSG) are commonly used in WECS, requiring robust control for optimal power extraction.
• Input channel disturbances can significantly impact the stability and performance of PMSG-WECS.

Purpose of the Study:

• To develop certainty equivalence-based robust sliding mode control protocols for maximum power extraction in uncertain PMSG-WECS.
• To address both structured and unstructured disturbances affecting the PMSG-WECS.
• To ensure the stability of internal dynamics and effectively control visible dynamics for trajectory tracking.

Main Methods:

• Transformation of the PMSG-WECS into a Bronwsky form (controllable canonical form) to analyze internal and visible dynamics.
• Design of certainty equivalence-based control strategies: conventional sliding mode control, terminal sliding mode control, and integral sliding mode control.
• Suppression of chattering phenomenon using equivalent estimated disturbances to enhance robustness.

Main Results:

• Internal dynamics of the transformed PMSG-WECS were proven stable, confirming minimum phase characteristics.
• The proposed sliding mode control strategies effectively tracked desired trajectories while managing system uncertainties.
• Chattering was significantly suppressed, and robustness was enhanced through the estimation of disturbances.

Conclusions:

• The developed certainty equivalence-based robust sliding mode control protocols are effective for maximum power extraction in uncertain PMSG-WECS.
• The control strategies demonstrate robustness against various disturbances and ensure system stability.
• Computer simulations in MATLAB/Simulink validated the theoretical findings and the efficacy of the proposed control techniques.