Performance Assessment of Control Loops: Theory and Applications PDF
Preview Performance Assessment of Control Loops: Theory and Applications
Advances in Industrial Control Springer-Verlag London Ltd. Other titles published in this Series: System Identification and Robust Control Steen Toffner-Clausen Genetic Algorithms for Control and Signal Processing K.F. Man, K.S. Tang, S. Kwong and W.A. Halan g Advanced Control of Solar Plants E.F. Camacho, M. Berenguel and F.R. Rubio Control of Modern Integrated Power Systems E. Mariani and S.S. Murthy Advanced Load Dispatch for Power Systems: Principles, Practices and Economies E. Mariani and S.S. Murthy Supervision and Control for Industrial Processes Björn Sohlberg Modelling and Simulation of Human Behaviour in System Control Pietro Carlo Cacciabue Modelling and Identification in Robotics Krzysztof Kozlowski Spacecraft Navigation and Guidance Maxwell Noton Robust Estimation and Failure Detection Rami Mangoubi Adaptive Internal Model Control Aniruddha Datta Price-Based Commitment Decisions in the Electricity Market Eric Allen and Marij a Ilic Compressor Surge and Rotating Stall Jan Tommy Gravdahl and Olav Egeland Radiotherapy Treatment Planning Oliver Haas Feedback Control Theory For Dynamic Traffic Assignment Pushkin Kachroo and Kaan Özbay Control Instrumentation for Wastewater Treatment Plants Reza Katebi, Michael A. Johnson an d Jacqueline Wilkie AutotuningofPID Controllers Cheng-Ching Yu Robust Aeroservoelastic Stability Analysis Rick Lind and Marty Brenner Biao Huang and Sirish L. Shah Performance Assessment of Control Loops Theory and Applications With 102 Figures Springer Biao Huang, PhD Sirish L. Shah, PhD Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada, T6G 2G6 ISBN 978-1-4471-1135-1 British Library Cataloguing in Publication Data Huang, Biao, 1962- Performance assessment of control loops : theory and Applications. - (Advances in industrial control) 1. Automatic control I. Title II. Shah, S. L. (Sirish L.), 1949- 629.8 ISBN 978-1-4471-1135-1 Library of Congress Cataloging-in-Publication Data Huang, Biao Performance assessment of control loops : theory and applications Biao Huang and Sirish L. Shah, p. cm. Includes biblipgraphical references. ISBN 978-1-4471-1135-1 ISBN 978-1-4471-0415-5 (eBook) DOI 10.1007/978-1-4471-0415-5 1. Automatic control. 2. Control theory. 3. Algorithms. I. Shah. S. L. (Sirish L.), 1949- . I.I Title. TJ213.H83 1999 99-31704 629.8—dc21 CIP Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, mis publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. © Springer-Verlag London 1999 Originally published by Springer-Verlag London Limited in 1999 Softcover reprint of the hardcover 1st edition 1999 M ATI AB® and SIMULINK® are the registered trademarks of The MathWorks, Inc., http://www.mathworks.com A significant portion of the material in this book has been reprinted from various journals and appears with permission from Elsevier Science and the Canadian Journal of Chemical Engineering. For the full citations of the papers involved please refer to page 7. The use of registered names, trademarks, etc. in this publication does not imply, even in teh absence of a specific statement, that such names are exempt from the relevant laws adn regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accurayc of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Typesetting: Camera ready by authors 69/3830-543210 Printed on acid-free paper SPIN 10728715 Advancesin Industrial Control SeriesEditors ProfessorMichaelJ.Grimble,ProfessorofIndustrialSystemsandDirector ProfessorMichaelA.Johnson,ProfessorofControlSystemsandDeputyDirector IndustrialControlCentre DepartmentofElectronicandElectricalEngineering UniversityofStrathdyde Graham HillsBuilding 50GeorgeStreet GlasgowGilQE UnitedKingdom SeriesAdvisoryBoard ProfessorDr-IngJ.Ackermann DLRInstitutfUrRobotikundSystemdynamik Postfach 1116 D82230WeBling Germany ProfessorLD.Landau Laboratoired'AutomatiquedeGrenoble ENSlEG,BP46 38402SaintMartind'Heres France DrD.C.McFarlane DepartmentofEngineering UniversityofCambridge CambridgeCB2 IQJ UnitedKingdom ProfessorB.Wittenmark DepartmentofAutomaticControl LundInstituteofTechnology POBox118 S-221 00Lund Sweden ProfessorD.W.Clarke DepartmentofEngineeringScience UniversityofOxford ParksRoad OxfordOXI 3PJ UnitedKingdom ProfessorDr-IngM.Thoma InstitutfUrRegelungstechnik UniversitatHannover Appelstr. 11 30167Hannover Germany ProfessorH. Kimura DepartmentofMathematicalEngineeringandInformationPhysics FacultyofEngineering TheUniversityofTokyo 7-3-1 Hongo BunkyoKu Tokyo 113 Japan ProfessorA.J. Laub CollegeofEngineering-Dean'sOffice UniversityofCalifornia OneShieldsAvenue Davis California95616-5294 UnitedStatesofAmerica ProfessorJ.B.Moore DepartmentofSystemsEngineering TheAustralian NationalUniversity ResearchSchoolofPhysicalSciences GPO Box4 Canberra ACT2601 Australia DrM.K.Masten TexasInstruments 2309Northcrest Plano TX75075 UnitedStatesofAmerica ProfessorTonBackx AspenTech EuropeB.V. DeWaal32 NL-5684PH Best TheNetherlands To Yali, Linda and my parents (B.H.) "A journeyofa thousand miles begins with a single step" - Chinese Proverb To my father and my'late mother (SLS) ;r ~ ~ ~ qrqS(r~~ ~ I ".. Right conduct and knowledge are indeed the most esteemed virtues .." - 38th verse ofChapter 4 ofthe Bhagwadgeeta SERIESEDITORS' FOREWORD The series Advances in Industrial Control aims to report and encourage technology transfer in control engineering. The rapid development of control technologyhas an impactonall areasofthe control discipline. New theory, new controllers,actuators, sensors, newindustrialprocesses, computermethods, new applications, new philosophies..., new challenges. Much of this development work resides in industrial reports, feasibility study papers and the reports of advanced collaborative projects. The series offers an opportunityfor researchers to present an extended exposition ofsuch new work in all aspects ofindustrial controlforwiderandrapiddissemination. Benchmarkingisatechniquefirst appliedbyRankXeroxin the late 1970sfor business processes. As a subject in the commercial arena, benchmarking thrives with, for example, a European Benchmarking Forum. It has taken rather longer forbenchmarkingtomake thetransfertothetechnicaldomainandevennowthe subjectismakingaslowheadway. Akeyresearch stepinthisdirectionwas taken by Harris (1989) who used minimum variance control as a benchmark for controller loop assessment. This contribution opened up the area and a significant specialist literature has now developed. Significant support for the methodologywasgivenbyHoneywellwhohavecontrollerassessmentroutines in their process control applications software; therefore, it is timely to welcome a (first) monograph on controller performance assessment by Biao Huang and Sirish Shah to the Advances in Industrial Control series. Industrial engineers, process controlengineers and the academic control communityshould find this structuredpresentationofthis newclass ofoperationaltechniques invaluable for self-studyorassupplementarytaughtcoursematerial. M.J. GrimbleandM.A. Johnson IndustrialControlCentre Glasgow,Scotland,U.K. June, 1999 PREFACE The design of advanced control algorithms has largely preoccupied the con trol practitioner's efforts. The rationale has been that systems which are difficult to control need advanced optimal, non-linear, adaptive or like con trol algorithms for better regulation. Although there is a variety of control design techniques, such as L1, H2, Hoo, etc., few techniques exist for ob jective measures ofcontrol loop performance or, conversely, measures of the level ofdifficulty in controlling a process variable from routine operating in dustrial process data. The control literature is relatively sparse on studies concerned with such proper or formal measures ofcontrol loop performance. The purpose of this monograph is to expose the reader to the most recent techniques for controller performance assessment. Specifically, this text pon ders questions such as the following: Is your controller healthy? Is it doing its job well? How can one obtain a non-invasive or a model-free assessment ofcontroller performance? PerformanceAssessmentof SISOIMIMOcontrollers enablesonetoasksimplistically: Howhealthyisyourcontroller? Isitdoingitsjobwell? v y Fig. 0.1. A simplistic depiction of the performance assessment problem. xii Preface One of the motivating factors as to why the industrial practitioner and the academic researcher may want to investigate this area is the explosive growth in the amount ofprocess data that is available for analysis. In almost all process environments, ranging from petroleum refining to pulp and paper processing, easy data access through Distributed Control Systems (DCS) is now a rule rather than an exception. In fact, in most process industries data is collected and simply archived. Estimates indicate that most chemical plants require over 100 gigabytes of storage space to archive a year's worth ofdata. The data-warehousing problem is a manifestation ofthe exponential increasein information flow as a result ofthe recent advances in networksand computers. In summary, we live in an information age in which the process industry world is awash with data. Properly archived, screened and sorted data can be a tremendous source of information. The question is how to extract useful information from this data and then put it to good use? The main objective of this research monograph is to suggest how routine closed loop data can be used to obtain non-invasive measures of the performance of the control loops in the plant. The theoretical results are supported by simulation plus experimental (in laboratory) and industrial evaluations. An equally important motivation for the recent interest in this area is an economic one. A typical industrial process includes thousands of con trol loops. Instrumentation technicians generally maintain and service these loops, but rather infrequently. Routine maintenance ofsuch loops at optimal settings can save a typical chemical complex hundreds ofthousands ofdollars a year. The development ofquality measures of performance for such control loops in industrial settings is therefore an important area ofindustrial inter est. Controller monitoring falls in the realm ofenterprise asset management. The thinking is that controllers, whether basic (i.e., PID type) or advanced, should be treated like other capital assets and they should therefore be mon itored on a routine basis. Thefollowing synopsisoutlines the major ingredientsofthis book. Perfor mance assessmentofunivariatecontrol loops is first carriedout by comparing the actual output variance with the minimum variance. The latter term is es timated by simple time series analysis of routine closed-loop operating data. The only prerequisite information required is knowledge ofthe process delay. When the process has a unit delay, then a whiteness test can be applied to the output as is typically done via the Shewhart chart. The analysis of the same problem in thefrequency domain has not received much attention in the literature. Preliminary results in this areaare presented here as they comple ment the time-domain analysis very well and provide an added perspective on the controller performance assessment problem. The univariate performance assessment concepts are then extended to the multivariate case. Akey to performance assessmentofmultivariate processes, using minimum variance control as a benchmark, is to estimate the bench mark performance from routine operating data with a priori knowledge of
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