ISA TUNIG IND CNTRL SYS-2001 Tuning of Industrial Control Systems (Second Edition).pdf

1、Tuning of IndustrialControl SystemsSecond EditionCorripioBOOK.book Page 1 Monday, October 16, 2000 9:35 PMCorripioBOOK.book Page 2 Monday, October 16, 2000 9:35 PMTuning of Industrial Control SystemsSecond Editionby Armando B. Corripio, Ph.D., P.E.Louisiana State UniversityNoticeThe information pres

2、ented in this publication is for the general education of the reader. Because neither the author nor the publisher have any control over the use of the information by the reader, both the author and the publisher disclaim any and all liability of any kind arising out of such use. The reader is expec

3、ted to exercise sound professional judgment in using any of the information presented in a particular application.Additionally, neither the author nor the publisher have investigated or considered the affect of any patents on the ability of the reader to use any of the information in a particular ap

4、plication. The reader is responsible for reviewing any possible patents that may affect any particular use of the information presented.Any references to commercial products in the work are cited as examples only. Neither the author nor the publisher endorse any referenced commercial product. Any tr

5、ademarks or tradenames referenced belong to the respective owner of the mark or name. Neither the author nor the publisher make any representation regarding the availability of any referenced commercial product at any time. The manufacturers instructions on use of any commercial product must be foll

6、owed at all times, even if in conflict with the information in this publication.Copyright 2001 ISAThe Instrumentation, Systems, and Automation Society.All rights reserved. Printed in the United States of America.No part of this publication may be reproduced, stored in retrieval system, or transmitte

7、d, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher.ISA67 Alexander DriveP.O. Box 12277Research Triangle ParkNorth Carolina 27709Library of Congress Cataloging-in-Publication DataCorripio, Armando B.Tunin

8、g of industrial control systems / Armando B. Corripio.- 2nd ed.p. cm.Includes bibliographical references and index.ISBN 1-55617-713-51. Process control-Automation. 2. Feedback control systems. I. Title.TS156.8. C678 2000670.4275-dc2100-010127CorripioBOOK.book Page 4 Monday, October 16, 2000 9:35 PMA

9、cknowledgementsThere are several people responsible for the production of this book. First of all, Paul W. Murrill, who was not only the first to teach me automatic process control and the one who got me into teaching and research but, also as the original Consulting Editor of the ILM series, inspir

10、ed me to write the first edition of this book. Secondly, Carlos A. Smith of the University of South Florida, who got me into teaching short courses and writing books. Also the many students who, through the years, attended my ISA short courses and the many students at Louisiana State University, gra

11、duate and undergraduate, who helped me learn along with them about process dynamics and control. In particular, Jacob Martin, Jr., A. Terrel Touchstone, Richard Balhoff, Dan Logue, Shaoyu Lin, Carl Thomas, Steve Hunter, Gene Daniel, Samuel Peebles, Umesh Chitnis, and Olufemi Adebiyi. Many of the pra

12、ctical tips I have included are drawn from my experience at Exxon Chemicals Baton Rouge Chemical Plant, working with my friends Doug White, Raju Hajare, and Jack Nylin.Finally, I would like to thank the people at ISAs Publications Department, Joice Blackson in particular, for inspiring me to write t

13、his second edition.This book is dedicated to my parents, who inspired me with their example of dedication, perseverance, and hard work.CorripioBOOK.book Page 5 Monday, October 16, 2000 9:35 PMCorripioBOOK.book Page 6 Monday, October 16, 2000 9:35 PMviiTABLE OF CONTENTSUnit 1: Introduction and Overvi

14、ew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1. Course Coverage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31-2. Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

15、1-3. Audience and Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41-4. Study Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41-5. Organization and Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16、41-6. Course Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51-7. Course Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Unit 2: Feedback Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17、. . . . . . . . . . . . . . . . 72-1. The Feedback Control Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92-2. Proportional, Integral, and Derivative Modes . . . . . . . . . . . . . . . . 132-3. Typical Industrial Feedback Controllers. . . . . . . . . . . . . . . . . . . . . 1

18、92-4. Stability of the Feedback Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222-5. Determining the Ultimate Gain and Period . . . . . . . . . . . . . . . . . . 242-6. Tuning for Quarter-decay Response . . . . . . . . . . . . . . . . . . . . . . . . 252-7. Need for Alternatives to

19、Ultimate Gain Tuning . . . . . . . . . . . . . . 312-8. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Unit 3: Open-Loop Characterization of Process Dynamics . . . . . . . . . . . . . . . . . 353-1. Open-Loop Testing: Why and How. . . . . . .

20、. . . . . . . . . . . . . . . . . . 373-2. Process Parameters from Step Test . . . . . . . . . . . . . . . . . . . . . . . . . 393-3. Estimating Time Constant and Dead Time. . . . . . . . . . . . . . . . . . . 413-4. Physical Significance of the Time Constant . . . . . . . . . . . . . . . . . . 453-

21、5. Physical Significance of the Dead Time. . . . . . . . . . . . . . . . . . . . . . 493-6. Effect of Process Nonlinearities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523-7. Testing Batch Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553-8. Summary . .

22、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Unit 4: How to Tune Feedback Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594-1. Tuning for Quarter-decay Ratio Response . . . . . . . . . . . . . . . . . . . 614-2. A Simple Met

23、hod for Tuning Feedback Controllers . . . . . . . . . . . 644-3. Comparative Examples of Controller Tuning . . . . . . . . . . . . . . . . 654-4. Practical Controller Tuning Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . 744-5. Reset Windup . . . . . . . . . . . . . . . . . . . . . . . .

24、 . . . . . . . . . . . . . . . . . . . 774-6. Processes with Inverse Response . . . . . . . . . . . . . . . . . . . . . . . . . . . 784-7. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Unit 5: Mode Selection and Tuning Common Feedback Loops .

25、 . . . . . . . . . . . . 835-1. Deciding on the Control Objective. . . . . . . . . . . . . . . . . . . . . . . . . . 855-2. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 865-3. Level and Pressure Control. . . . . . . . . . . . . . . . . . . . .

26、. . . . . . . . . . . 885-4. Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 945-5. Analyzer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 965-6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27、. . . . . . . . . . . . . . . . . . 97Unit 6: Computer Feedback Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 996-1. The PID Control Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1016-2. Tuning Computer Feedback Controllers . . . . . . . .

28、. . . . . . . . . . . 1086-3. Selecting the Controller Processing Frequency . . . . . . . . . . . . . . 1156-4. Compensating for Dead Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1176-5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

29、. . 121CorripioBOOK.book Page vii Monday, October 16, 2000 9:35 PMviii Table of ContentsUnit 7: Tuning Cascade Control Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1257-1. When to Apply Cascade Control . . . . . . . . . . . . . . . . . . . . . . . . . . 1277-2. Selecting Co

30、ntroller Modes for Cascade Control. . . . . . . . . . . . . 1307-3. Tuning Cascade Control Systems. . . . . . . . . . . . . . . . . . . . . . . . . . 1317-4. Reset Windup in Cascade Control Systems . . . . . . . . . . . . . . . . . 1397-5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . .

31、. . . . . . . . . . . . . . . . . . . . 142Unit 8: Feedforward and Ratio Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1438-1. Why Feedforward Control? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1458-2. The Design of Linear Feedforward Controllers . . . .

32、 . . . . . . . . . . 1508-3. Tuning Linear Feedforward Controllers. . . . . . . . . . . . . . . . . . . . 1528-4. Nonlinear Feedforward Compensation . . . . . . . . . . . . . . . . . . . . 1578-5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

33、Unit 9: Multivariable Control Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1679-1. What Is Loop Interaction? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1699-2. Pairing Controlled and Manipulated Variables. . . . . . . . . . . . . . 1739-3. Design an

34、d Tuning of Decouplers . . . . . . . . . . . . . . . . . . . . . . . . . 1839-4. Tuning Multivariable Control Systems . . . . . . . . . . . . . . . . . . . . . 1889-5. Model Reference Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1919-6. Summary . . . . . . . . . . . . . .

35、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194Unit 10: Adaptive and Self-tuning Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19710-1. When Is Adaptive Control Needed? . . . . . . . . . . . . . . . . . . . . . . . 19910-2. Adaptive Control by Preset Compen

36、sation . . . . . . . . . . . . . . . . . 20210-3. Adaptive Control by Pattern Recognition . . . . . . . . . . . . . . . . . . 20910-4. Adaptive Control by Discrete Parameter Estimation . . . . . . . . . 21210-5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

37、. . . . . . 220Appendix A: Suggested Reading and Study Materials. . . . . . . . . . . . . . . . . . . . 223Appendix B: Solutions to All Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38、 . . . . . . . . . . . . . . . . . . . . . . . 251CorripioBOOK.book Page viii Monday, October 16, 2000 9:35 PMUnit 1:Introduction andOverviewCorripioBOOK.book Page 1 Monday, October 16, 2000 9:35 PMCorripioBOOK.book Page 2 Monday, October 16, 2000 9:35 PM3UNIT 1Introduction and OverviewWelcome to Tu

39、ning of Industrial Control Systems. The first unit of this self-study program provides the information you will need to take the course.Learning Objectives When you have completed this unit, you should be able to:A. Understand the general organization of the course.B. Know the course objectives.C. K

40、now how to proceed through the course.1-1. Course CoverageThis book focuses on the fundamental techniques for tuning industrial control systems. It covers the following topics:A. The common techniques for representing and measuring the dynamic characteristics of the controlled process.B. The selecti

41、on and tuning of the various modes of feedback control, including those of computer- and microprocessor-based controllers.C. The selection and tuning of advanced control techniques, such as cascade, feedforward, multivariable, and adaptive control.When you finish this course you will understand how

42、the methods for tuning industrial control systems relate to the dynamic characteristics of the controlled process. By approaching the subject in this way you will gain insight into the tuning procedures rather than simply memorizing a series of recipes.Because microprocessor- and computer-based cont

43、rollers are now widely used in industry, this book will extend the techniques originally developed for analog instruments to digital controllers. We will examine tuning techniques that have been specifically developed for digital controllers as well as those for adaptive and auto-tuning controllers.

44、No attempt is made in this book to provide an exhaustive presentation of tuning techniques. In fact, we have specifically omitted techniques based on frequency response, root locus, and state space analysis because they are more applicable to electrical and aerospace systems than to industrial Corri

45、pioBOOK.book Page 3 Monday, October 16, 2000 9:35 PM4 Unit 1: Introduction and Overviewprocesses. Such techniques are unsuitable for tuning industrial control systems because of the nonlinear nature of industrial systems and the presence of transportation lag (dead time or time delay).1-2. PurposeTh

46、e purpose of this book is to present, in easily understood terms, the principles and practice of industrial controller tuning. Although this course cannot replace actual field experience, it is designed to give you the insights into the tuning problem to speed up your learning process during field t

47、raining.1-3. Audience and PrerequisitesThe material covered will be useful to engineers, first-line supervisors, and senior technicians who are concerned with the design, installation, and operation of process control systems. The course will also be helpful to students in technical schools, college

48、s, or universities who wish to gain some insight into the practical aspects of automatic controller tuning.There are no specific prerequisites for taking this course. However, you will find it helpful to have some familiarity with the basic concepts of automatic process control, whether acquired thr

49、ough practical experience or academic study. In terms of mathematical skills, you do not need to be intimately familiar with some of the mathematics used in the text in order to understand the fundamentals of tuning. This book has been designed to minimize the barrier that mathematics usually presents to students understanding of automatic control concepts.1-4. Study MaterialsThis textbook is the only study material required in this course. It is an independent, stand-alone textbook that is uniquely and specifically designed for self-style.Appendix A contains a list of suggested r