Fractional order automatic tuning of PI^λD controller for stable processes

Area of Science:

• Control Systems Engineering
• Automation and Process Control
• Fractional-Order Systems

Background:

• Traditional PID controllers struggle with complex dynamics and disturbances.
• Fractional-order controllers offer enhanced flexibility but require sophisticated tuning methods.
• Accurate automatic tuning is crucial for robust industrial process control.

Purpose of the Study:

• To develop a modified fractional-order relay-based auto-tuning method for PIλD controllers.
• To improve the accuracy and stability of control systems, especially under load disturbances.
• To leverage fractional calculus for enhanced controller performance.

Main Methods:

• A modified relay incorporating a series PIλ controller was utilized.
• Limit cycle parameters (critical frequency, peak amplitude) were extracted for controller design.
• Phase margin criteria and Nyquist curves guided the determination of controller parameters (proportional gain, integral time, derivative time).
• The fractional order (λ) was optimized to minimize output harmonics.

Main Results:

• The proposed method successfully extracts essential parameters for PIλD controller design.
• The inclusion of λ in the relay controller reduces output harmonics, improving accuracy.
• Simulations demonstrated the effectiveness of the auto-tuning method and the designed PIλD controller for stable processes.

Conclusions:

• The modified fractional-order relay auto-tuning technique provides an effective approach for designing PIλD controllers.
• This method enhances control system accuracy and stability, particularly in the presence of load disturbances.
• Fractional-order control offers significant advantages for advanced process automation.