Dead-Time Compensation and Performance Monitoring in Process Control Ingimundarson, Ari

147 Pages·2017·4.98 MB·English

Dead-Time Compensation and Performance Monitoring in Process Control
Ingimundarson, Ari
2003
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Citation for published version (APA):
Ingimundarson, A. (2003). Dead-Time Compensation and Performance Monitoring in Process Control. [Doctoral
Thesis (monograph), Department of Automatic Control]. Department of Automatic Control, Lund Institute of
Technology (LTH).
Total number of authors:
1
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LUND UNIVERSITY
PO Box 117
221 00 Lund
[phone]
Dead-Time Compensation and
Performance Monitoring
in Process Control

Dead-Time Compensation and
Performance Monitoring
in Process Control
Ari Ingimundarson
Department of Automatic Control
Lund Institute of Technology
Lund, January 2003
To Bea
Department of Automatic Control
Lund Institute of Technology
Box 118
SE-221 00 LUND
Sweden
ISSN 0280–5316
ISRN LUTFD2/TFRT–1064–SE
&c2003 by Ari Ingimundarson. All rights reserved.
Printed in Sweden by Bloms i Lund Tryckeri AB.
Lund 2003
Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Part I. Topics in Dead-Time Compensation . . . . . . . . . . . 9
Introduction to Dead-Time Compensation . . . . . . . . . . . . 11
1. Background and Motivation . . . . . . . . . . . . . . . . 11
2. Research on Dead-Time Compensation . . . . . . . . . . 12
3. Outline and Summary of Contribution . . . . . . . . . . 13
1. Robust tuningproceduresof dead-time compensatingcon-
trollers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2. Identification . . . . . . . . . . . . . . . . . . . . . . . . . 17
3. Dead-time compensation . . . . . . . . . . . . . . . . . . 22
4. Stable Case . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5. Unstable case, integrating processes . . . . . . . . . . . 35
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2. Performancecomparison betweenPID anddead-time com-
pensating controllers . . . . . . . . . . . . . . . . . . . . . . . 49
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 50
2. Comparison criteria . . . . . . . . . . . . . . . . . . . . . 50
3. Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Part II. Performance Monitoring of l -Tuned Controllers . . 71
1. Introduction to Performance Monitoring . . . . . . . . . . 73
1.1 Control Performance in the Process Industry . . . . . . 73
1.2 Why is Performance Poor? . . . . . . . . . . . . . . . . . 74
1.3 Desired Properties of CLPM&D Methods . . . . . . . . . 75
5
Contents
1.4 The Following Chapters . . . . . . . . . . . . . . . . . . . 77
2. Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 78
2.2 Academic Work . . . . . . . . . . . . . . . . . . . . . . . . 79
2.3 Indices Calculated from Time-Series Models . . . . . . . 81
2.4 User Defined Benchmarks . . . . . . . . . . . . . . . . . 87
3. l -Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 92
3.2 Assumptions on Tuning . . . . . . . . . . . . . . . . . . . 93
3.3 The Monitoring Algorithm: l -Monitoring . . . . . . . . . 96
3.4 Recursive Implementation of l -Monitoring . . . . . . . 100
3.5 Validation on Industrial Data . . . . . . . . . . . . . . . 101
3.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4. Gradient Monitoring . . . . . . . . . . . . . . . . . . . . . . . 112
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 112
4.2 Iterative Feedback Tuning . . . . . . . . . . . . . . . . . 113
4.3 Monitoring the Gradient . . . . . . . . . . . . . . . . . . 115
4.4 Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . 117
4.5 Recursive Implementation of the Normalized Gradient . 121
4.6 Use of the Gradient . . . . . . . . . . . . . . . . . . . . . 121
4.7 Discussions and Future Work . . . . . . . . . . . . . . . 129
4.8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 129
A. Industrial data . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
6
Preface
This thesis addresses two topics in process control. The topics are dead-
time compensation and closed-loop performance monitoring. The first is
concerned with the control of processes with long dead-time. The second
is about monitoring of feedback controllers to know how well they are
performing. The thesis is divided into two parts accordingly. The first
part is composed of two published articles with an introduction while the
second part is composed of 4 chapters.
As an engineering discipline, process control has many exiting chal-
lenges to offer researchers within the academic community. One of the
most difficult challenge researchers face is to transmit results of their
research to the practitioners within the field. It has been the hope of the
author when writing this thesis that the results might be of relevance to
practitioners.
ThethesisistheresultofafewyearsofPh.D.studies.Duringtheyears
some of the material has been published at other occasions. The research
on dead-time compensation was published in the following articles:
Ingimundarson, A. and T. Hägglund D2000aE: “Closed-loop identification
of first-order plus dead-time model with method of moments.” In
ADCHEM2000,IFACInternationalSymposiumonAdvancedControl
ofChemicalProcesses. Pisa, Italy.
Ingimundarson,A.andT.HägglundD2000bE:“Robustautomatictuningof
an industrial PI controller for dead-time systems.” InIFACWorkshop
onDigitalControl–Past,present,andfutureofPIDControl.Terrassa,
Spain.
The two articles included in this thesis are:
Ingimundarson,A.andT.HägglundD2001E:“Robusttuningproceduresfor
dead-time compensating controllers.”ControlEngineeringPractice, 9,
pp. 1195–1208.
7
Preface
Ingimundarson, A. and T. Hägglund D2002E: “Performance comparison
between PID and dead-time compensating controllers.” Journalof
ProcessControl, 12, pp. 887–895.
The second part of the thesis has been partially published in :
Ingimundarson, A. D2002E: “Performance monitoring of PI controllers
usingasyntheticgradientofaquadraticcostfunction.”InIFACWorld
Congress. Barcelona, Spain.
Work that has not been included in this thesis but was performed during
the Ph.D. studies was published in
Solyom, S. and A. Ingimundarson D2002E: “A synthesis method for robust
PID controllers for a class of uncertain systems.” AsianJournalof
Control, 4:4.
Also the following article has been submitted.
Ingimundarson, A. and S. Solyom D2002E: “ On a synthesis method for
robust PID controllers for a class of uncertainties”, Submitted for
publication inEuropeanControlConferenceECC2003.
Acknowledgments
It is a privilege to be a Ph.D. student at the Department of Automatic
ControlatLundInstituteofTechnology.Thedepartmentissecondtonone
inprovidingopportunitiesforPh.D.studentstorealizeanyambitionthey
might have in research on automatic control. The nice atmosphere there
is due to the staff and my thanks go out to all of them.
IwouldliketothanktheCenterforChemicalProcessDesignandCon-
trol DCPDCE and The Swedish Agency for Innovation Systems DVinnovaE
for financial support.
Iwouldliketothankmysupervisor,ToreHägglund,foralwayshaving
timeandapositiveattitudetomostideas.Thepeoplethatproofreadver-
sions of the manuscript, Björn Wittenmark and Johan Eker are thanked
for their comments.
Finally, I would like to thank the people that have indirectly con-
tributed to making this thesis a reality. Friends here in Sweden have
made the stay much more enjoyable. My family in Iceland are thanked
for support and encouragement. At last, I would like to thank the person
who made the whole thing possible, my beloved Bea.
Ari
8
Part I
Topics in Dead-Time
Compensation