Emerson Exchange 365

DeltaV 12.3 PIDPlus option?

Does anybody have any experience using the PIDPlus option for a PID function block?  I have an application where the PV is intermediate and this appears be a good option.  The documentation only mentions how to select the option, but not what other parameters are required.

gxmontes

• 26 Apr 2017 8:52 PM
• Cancel

4 Replies

• Matt Stoner

  

  • 26 Apr 2017 9:06 PM

  James Beall is the man for this one!

  • Cancel
• James Beall

  

  • 27 Apr 2017 1:13 AM

  The PIDPlus is very good when the update rate of the PV varies or is long compared to the actual process response. This feature of PIDPlus detects an update of the PV and executes the Integral and Derivative action based on the time since the last PV update. If the PV is a digitally communicated (e.g. from an analyer), then the PV will not change ANY until a new value is communicated. However, if the PV comes from an AI channel, any slight change in the PV (e.g from noise) will cause the PIDPlus to think an update of the PV has occured even when the the PV may not have made true change. For this case, you should pre-condition the PV with a CALC block that includes a "hysteresis" value that the "PV change from the last transferred value" must exceed in order to transfer an updated PV. Next, simply tune the PID as if the PV update time is negligble. Try it on a simulated loop with a variable update time and you will get a feel for it!
  James

  • Cancel
• gxmontes

  

  • 27 Apr 2017 12:28 PM

  In reply to James Beall:

  James, thanks for the quick response and explanation!

  • Cancel
• gxmontes

  

  • 27 Apr 2017 2:10 PM

  In reply to Matt Stoner:

  Thanks for pointing me in the right direction!

  • Cancel