Home » PID Tuning Recommendations based on Process Dynamics
Control Systems

PID Tuning Recommendations based on Process Dynamics

Knowing which control actions to focus on first is a matter of characterizing the process (identifying whether it is self-regulating, integrating, runaway, noisy, has lag or dead time, or any combination of these traits based on an open-loop response test (Note1) ) and then selecting the best actions to fit those characteristics.

Note 1 : Recall that an open-loop response test consists of placing the loop controller in manual mode, introducing a step-change to the controller output (manipulated variable), and analyzing the time-domain response of the process variable as it reacts to that perturbation.

The following table shows some general recommendations for fitting PID tuning to different process characteristics

PID Tuning recommendations

General rules:

  • Use no derivative action if the process signal is “noisy”
  • Use proportional action sparingly if the process signal is “noisy”
  • The slower the time lag(s), the less integral action to use (a good approximation is to set the integration time τi equal to the measured lag time of the process)
  • The higher-order the time lag(s), the less proportional action (gain) to use
  • Self-regulating processes need integral action
  • Integrating processes need proportional action
  • Dead time requires a reduction of all PID constants below what would normally work

Once you have determined the basic character of the process, and understand from that characterization what the needs of the process will be regarding P, I, and/or D control actions, you may “experiment” with different tuning values of P, I, and D until you find a combination yielding robust control.

Similar Articles:

Related Articles

PID Controller Gains Effect on Manipulated Variable

S Bharadwaj Reddy

Control Room Alarm Management Practices

S Bharadwaj Reddy

Process Dynamics and PID Controller Tuning

S Bharadwaj Reddy

The need for automatic controls

S Bharadwaj Reddy

DCS versus PLC Architecture

S Bharadwaj Reddy

Integrating Processes – Liquid Level Control

S Bharadwaj Reddy

Leave a Comment

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

WordPress Image Lightbox