Dear experts here,
Currently I am working on a Closed-Loop Setpoint Response tuning method which need me to switch the PID controller to Proportional-Only. What is the right method to get this type of controller? Set the RESET to 0 in order to disable the integral? Or is it necessary to change the STRUCTURE parameter at the PID block to "P on Error, D on PV"? Currently at DCS, the settings is "PI on Error, D on PV". I tried to change the settings into "P on Error, D on PV" to disable the integral action. But when I turn the controller from manual to Auto, suddenly the controller output goes to zero. It caused an upset to the process. I am not sure what is the problem, because before this no such problem occurred in the plant. Can anyone here provide me the correct procedure to get the P-Only controller? Thank You.
In reply to neilrbrown:
Dear, for disable the integral, set I = 99999 . !! that's what I was told
I tried, and it doesn't work
In reply to Jean-Marc Dufert:
In reply to LaurentB:
In reply to Brian Hrankowsky:
Brian is correct, setting the Reset to 0 (0 seconds per repeat) on a DeltaV PID block makes the integral action VERY fast, approximately the execution time of the module as Brian says. I usually put 999999 to temporarily turn in the integral action off. To permanently turn it off, change the PID/Structure to one of the PD structures (no I). I have never seen the PID change its output if the PID is in Manual when the download occurs. Brian is correct also that you can put the PID/MODE to out of service (OOS) in the on-line and make this change without a download. This may cause the PID PV, OUT, etc, status to change which could cause some issues if these parameters are monitored by some other code.
When using the DeltaV InSight Tuning tools (On Demand Tuning or Adaptive Tuning) you MUST set the process type to Integrating if it is an integrating process, otherwise the results will not be appropriate. As Neil recommended, you need an understanding of the PID action and some understanding of basic tuning to evaluate the results of any automatic loop tuner. A course on the topic is always helpful. A simulation in DelaV Simulate or even in the plant DeltaV is invaluable! Here are a couple of articles that I wrote in the ISA Intech magazine that should be helpful!
Good luck!
In reply to Mark Bendele:
In reply to James Beall: