PID Tuning for Self Regulating Processes - Greg McMillan Deminar

Interactive Opportunity Assessment Demo and Seminar (Deminar) Series for Web Labs – PID Tuning for Self-Regulating Processes June 9, 2010 Sponsored by Emerson, Experitec, and Mynah Created by Greg McMillan and Jack Ahlers www.processcontrollab.com Website - Charlie Schliesser (csdesignco.com)

Welcome
Gregory K. McMillan
Greg is a retired Senior Fellow from Solutia/Monsanto and an ISA Fellow. Presently, Greg contracts as a consultant in DeltaV R&D via CDI Process & Industrial. Greg received the ISA “Kermit Fischer Environmental” Award for pH control in 1991, the Control Magazine “Engineer of the Year” Award for the Process Industry in 1994, was inducted into the Control “Process Automation Hall of Fame” in 2001, and was honored by InTech Magazine in 2003 as one of the most influential innovators in automation. Greg is the author of numerous books on process control, his most recent being Essentials of Modern Measurements and Final Elements for the Process Industry. Greg has been the monthly “Control Talk” columnist for Control magazine since 2002. Greg’s expertise is available on the web site: http://www.modelingandcontrol.com/

Top Ten Signs a Startup Has Gone Wrong
( 10) Product tanks are empty
(9) Waste tanks are full
(8) The startup team and the DCS has negative free time
(7) The entire design team is in the control room
(6) The whole research group is in the control room
(5) The managers have left the control room
(4) The consoles are lit up like a pin ball machine
(3) Operators keel over from doughnut overdose
(2) A collection is taken for the startup budget
And the Number 1 Sign :

Top Ten Signs a Startup Has Gone Wrong
(1) The order for souvenir baseball caps is cancelled

Time (seconds) % Controlled Variable (CV) or % Controller Output (CO)  CO  CV  o  p K p =  CV  CO  CV CO CV self-regulating process time constant Self-regulating process gain (%/%) Response to change in controller output with controller in manual observed process deadtime Self-Regulating Process Response

Conical Tank in MIT Anna University Lab http://www.controlglobal.com/articles/2010/LevelControl1002.html

Gravity discharge flow makes the level response self-regulating (increase in level head increases flow through discharge valve) Increase in cross sectional area with level increases process time constant making process response slower Conical Tank Detail

Performance of Linear PID Level Controller for Conical Tank

Process Models Automatically Identified for Operating Regions

Performance of Adaptive PID Level Controller for Conical Tank

Click on magnifying glass to get detail view of limits and tuning Click on Duncan to get DeltaV Insight for “On-Demand” and “Adaptive” tuning Slide

Control Valve Flow Characteristics

Equal Percentage Flow Characteristic Slide

“ On-Demand Tuning” automatically identifies dynamics from relay oscillation introduced click on PID tag and then Tune Slide

“ Adaptive Tuning” automatically identifies dynamics from setpoint or manual output change or injected pulse (For More Info See Emerson Exchange 2009 Presentation on DeltaV Insight for Loop Monitoring and Tuning) click on PID tag and then Tune Slide

“ Adaptive Control” automatically identifies dynamics in each region Process gain is approximately proportional to flow for equal percentage flow characteristic Slide

Identification Out Limit that sets deadzone should be set approximately equal to valve deadband and stick-slip near closed position Learning Setup (triggers, injection, search, process, initialization, and options for model identification ) Slide

Simulate to show gain and phase margin and load and setpoint response for tuning settings Slide

Demo of Adaptive Control
Objective – Show adaptive control of fast nonlinear self-regulating processes (Liquid Flow and Liquid Pressure)
Activities:
For Liquid Flow Loop:
Show nonlinear control valve characteristic
Run “ On-Demand Tuner ” (0.2  K u and 0.6  T u )
Run “ Adaptive Tuner ” (initially SP = 40-35) (Lambda factor = 1 & setpoint trigger = 2%)
With Adaptive Mode “Off” make setpoint change region 5 (SP = 85-90)
With Adaptive Mode “Off” make setpoint change region 1 (SP = 5-10)
Review “ Adaptive Control ” screen
Review “ Model Viewing ” screen
Review “ Learning Setup ” screen
Review “ Simulate ” screen
With Adaptive Mode “Partial” make same setpoint changes in region 1 and 5
For Liquid Pressure Loop:
Show nonlinear process gain
Repeat above Tuner and Adaptive Control runs and reviews for pressure loop (initially
SP = 50-45, make Adapt mode tests in Region 5 SP = 80-85 and Region 1 SP = 10-15)

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Join Us June 23, Wednesday 10:00 am CDT
PID Tuning for Near-Integrating Processes (How to Reduce the Tuning Time for Column and Vessel Temperature and Pressure Loops by 90%)
Look for a recording of Today’s Deminar later this week at:
www.ModelingAndControl.com
www.EmersonProcessXperts.com

QUESTIONS?

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PID Tuning for Self Regulating Processes - Greg McMillan Deminar

by Jim Cahill on Jun 09, 2010

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PID Tuning for Self Regulating Processes - Greg McMillan Deminar — Presentation Transcript