Control Performance Management in Industrial Automation: Assessment, Diagnosis and Improvement of Control Loop Performance PDF
Preview Control Performance Management in Industrial Automation: Assessment, Diagnosis and Improvement of Control Loop Performance
Advances in Industrial Control Forfurthervolumes: www.springer.com/series/1412 Mohieddine Jelali Control Performance Management in Industrial Automation Assessment, Diagnosis and Improvement of Control Loop Performance Dr.-Ing.MohieddineJelali FacultyofPlant,EnergyandMachine Systems CologneUniversityofAppliedSciences Koeln,Germany ISSN1430-9491 ISSN2193-1577(electronic) AdvancesinIndustrialControl ISBN978-1-4471-4545-5 ISBN978-1-4471-4546-2(eBook) DOI10.1007/978-1-4471-4546-2 SpringerLondonHeidelbergNewYorkDordrecht LibraryofCongressControlNumber:2012951835 ©Springer-VerlagLondon2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof thematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation, broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionorinformation storageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodology nowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerptsinconnection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. 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Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) FürDoris,YasminundDunja Series Editors’ Foreword The series Advances in Industrial Control aims to report and encourage technol- ogy transfer in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. New theory, new controllers, actuators, sensors, new industrial processes, computer methods, new applications, new philosophies..., new challenges. Much of this development work resides in industrialreports,feasibilitystudypapersandthereportsofadvancedcollaborative projects.Theseriesoffersanopportunityforresearcherstopresentanextendedex- position of such new work in all aspects of industrial control for wider and rapid dissemination. ProfessorThomasJ.Harris’s1989paperonthe“AssessmentofClosed-loopPer- formance”demonstratedhowtobenchmarktheperformanceofcommissionedcon- trollersusingindustrialplantdatawithouttheneedforintrusivecontrolexperiments on production plant. This paper appeared against a background of control system auditsthatshowedalargeproportionofcontrolloopsinmanyindustriestobeper- forming poorly and capable of much better performance. The causes of poor per- formanceincludepoorlytunedcontrollers,controllerstiction,andotherproblems. From 1989,and buildingon the foundation of Professor Harris’s work, many new controllerassessmenttechniquesweredevisedandaddedtothepublishedliterature. Otheracademicsandengineersbegantolookmorepreciselyatthecausesofpoor controlthusbroadeningthescopeandanalysisoftheissuesthatcontrolassessment techniquesshouldaddress. As Editors of the Advances in Industrial Control monograph series, we were keen to have a small corpus of influential volumes in the series on this growing and important field in industrial control. In consequence, the series contains the monographs: • Performance Assessment of Control Loops by Biao Huang and Sirish L. Shah (ISBN978-1-85233-639-4,1999). • Process Control Performance Assessment: From Theory to Implementation by Andrzej W. Ordys, DamienUduehiand MichaelA. Johnson (Eds.) (ISBN 978- 1-84628-623-0,2007). vii viii SeriesEditors’Foreword • DiagnosisofProcessNonlinearitiesandValveStiction:Data-DrivenApproaches byMd.AliAhammadShoukatChoudhury,SirishL.ShahandNinaF.Thornhill (ISBN978-3-540-79223-9,2008). • Detection and Diagnosis of Stiction in Control Loops: State of the Art and Ad- vanced Methods by Mohieddine Jelali and Biao Huang (Eds.) (ISBN 978-1- 84882-774-5,2010). Theseinfluentialmonographsremainveryrelevanttothefieldofcontrollerper- formanceassessmentstudiesandarestillavailable. Now, just over two decades on from Professor Harris’s initial impetus there is anextensivebodyofcontrollerassessmenttheoryandmethodsinthearchivalpub- lishedliterature.Thus,itisanappositetimetohavethisworkdocumentedandde- scribedasafullyformedindustrialscience.Wearethereforefortunatetowelcome intotheseries MohieddineJelali’s monograph,ControlPerformanceManagement inIndustrialAutomation:Assessment,Diagnosis,andImprovementofControl-Loop Performance.Itisacomprehensivevolumethatcoversthefieldinfourparts:tech- niquesforcontrollerperformanceassessment,detection,anddiagnosisofcontroller performance problems, techniques for controller improvement and closes with in- dustrialapplicationsandtools.Alsousefulisthereferencesectionthatarchivesthe detailsofover480contributionstotheextensiveliteratureofthefield. Dr.Jelali’smonographshowsthatthescienceofcontrollerperformanceassess- mentiswellfoundedandthriving.However,itisinterestingtoreflectwherefuture developmentsinthefieldmightarise.Oneperenniallyvexingtopicisthatofestab- lishingtherelationshipbetweeninvestingincontrolperformancemanagement(and moregenerally,controlsystemsperse)andeconomicbenefittothecompanyenter- prise. There is still a dearth of analysis and methods in this direction. In a similar vein,asalutaryChap.15inthemonographlooksatindustrialapplicationsandthe take-up of the ideas and methods presented. Dr. Jelali gives it as his opinion that only three commercial software products comprehensively cover the concepts and algorithmsofcontrolperformancemanagementfoundinthemonograph,andgoes ontosaythatofthelistoftenorsopackagesdescribed“onlyasmallproportionof themethodsfoundinthisbookcanbefoundinthesepackages”.Clearly,thereisa wealthofideas,methods,andalgorithmscollatedinthismonographthatareavail- ableforusebytheindustrialcontrolandprocessengineer;thepotentialisthere.In thisway,Dr.Jelali’smonographmeetsoneofthekeyobjectivesoftheAdvancesin IndustrialControlseries;thatofpromotingnewideasandtechniquesthatcanhelp theindustrialengineerenhancetheperformanceofcontrolsystemstechnology. IndustrialControlCentre, M.J.Grimble Glasgow,Scotland,UK M.A.Johnson Preface Aimof theBook Control loops are the most important components in automation systems. Product quality, operation safety, material and energy consumption, and thus the financial performance,aredirectlyorindirectlylinkedtotheperformanceofcontrolsystems. Toachieve,restore andsustaintopperformanceof controlloopsis thus avitalin- terest for any company. Since process control systems are very complex, usually comprising different hierarchical levels, it is hopeless to maintain them on regular basisbyplantpersonal.Thisisalsothemainreasonwhyalargeportionofindustrial controlloopshassignificantperformanceproblems,asfoundoutbyauditscarried out regularly since the 1990s. All these factors have contributed to the growth of thecontrolperformancemonitoring(CPM)technologyandapplicationsinthelast decade. CPM provides a framework for automatically and systematically assess- ingtheperformanceofcontrolloops,detectinganddiagnosingroot-causesofpoor performance, as well as suggesting measures to improve control performance or avoidperformancedegradation.Atthispoint,itisstressedthatanyCPMtechnique should be non-invasive to be accepted in industrial practice. That is, the analysis shouldalways be carried outbased ononlyroutine operatingdatawith limitedor noadditionalprocessknowledgeandwithouttheneedforanyexperimentationwith theplant,noteveninclosedloop. Since the key research by Harris (1989), the control community has developed numerous methods that focus on the performance assessment of control loops. At the centre of these approaches is the concept of minimum variance benchmark- inganddifferentmodificationsorextensions,whichhaveattractedmuchattention. Meanwhile, there is a large number of techniques for basic and advanced perfor- manceassessment,detectionanddiagnosisofdifferentsourcesofpoorperformance (badcontrollertuning,processnonlinearities,oscillations,etc.).Usually,emphasis isplacedonsingletechniquestodetectspecialperformanceproblemsorplantfaults. ThisisthefirstmonographthatdealswiththecompleteCPMtechnology,from controller assessment (minimum-variance-control-based and advanced methods), ix x Preface overdetectionanddiagnosisofcontrolloopproblems(processnonlinearities,oscil- lations, actuator faults), to the improvement of control performance (maintenance, re-designofloopcomponents,automaticcontrollerre-tuning).Itprovidesacontri- bution towards the development and application of completely self-contained and automaticmethodologiesinthefield.Moreover,withinthiswork,manyCPMtools have been developed that go far beyond available CPM packages. Industrial data fromalargenumberofcontrolloopsindifferentindustrialfields(building,chem- icals, mining, mineral and metal processing) have been used to demonstrate the presented strategies and methods. Systematic procedures for automatic and con- tinuous control performance monitoring, maintenance and optimisation have been recommended, combining different control performance metrics and assessment, diagnosis and improvement methods. The main objective is to sustain top control performanceduringthewholelifecycleofthecontrolsystem,despitedifferentand changingoperationalconditions. Contributionsof theBook Inthelightofthecontrol-systemlife-cyclemanagementintroducedabove,thefirst contributionofourworkistoprovidestrategiesandmethodsforestablishinganew practiceofintegratedcontroldesignandperformancesupervisionoftechnicalpro- cesses,asillustratedinFig.1. The focus of this book is only on the last three stages, i.e., performance mon- itoring, condition monitoring and diagnosis, and CPM-based controller re-tuning. The book is however NOT on control system design or implementation, which is the topic of many standard texts. To the knowledge of the author, all major as- pects of CPM, from controller assessment (minimum-variance-control-based and advancedmethods),overdetectionanddiagnosisofcontrolloopproblems(process non-linearities, oscillations, actuator faults), to the improvement of control perfor- mance(maintenance,re-designofloopcomponents,automaticcontrollerre-tuning) aretreatedforthefirsttimeinthisworkfromacommonviewpoint. Morespecifically,thecontributionsandmessagesofthepresentbookarestated asfollows: 1. Review, Evaluation and Industrial Application of Available Methods and Sys- tems.Acomprehensiveandcriticalreviewofthecurrentstatusinthecomplete CPM technology, including techniques for performance assessment, diagnosis and improvement. Standard methods and advanced new methods are presented as well. This provides an insight into the assumptions and fundamental limita- tionsofeachcontrolperformanceassessmentmethod,sinceeachofthevarious techniques signifies specific information about the nature of the process. Most CPMalgorithmspresentedinthebookhavebeenimplementedandtestedbythe authorinMATLAB/Simulink. An evaluation of publications during the 15 years after the key work by Har- ris (1989) shows some trends in the application of a number of control perfor- mance metrics and methods in different process industries. Also included is an Preface xi Fig.1 Flowdiagramoftheprocesscontroldesignandsupervisionprocedure overviewofCPMpackagesthathavebeendevelopedand/orwhicharecommer- ciallyavailable.Meritsanddrawbacksofthemethodsarealsohighlighted.Some control benchmarking techniques are compared in terms of parameters/data re- quirementsandperformancetodrawguidelinesforthechoiceofthemostsuit- abletechniqueorcombinationoftechniques. The majority of the methods presented are illustrated with real data from in- dustrialcontrolloopsfromdifferentindustrialfields,includingchemicals,petro- chemicals, pulp & paper plants, commercial buildings, power plants, mineral processing,miningandmetalprocessing.Someinformationabouttheseloopsis giveninAppendixC. 2. Improved and New Methods for Control Performance Assessment and Diagno- sis.Itisnotsufficientandoftendangeroustorelyonasingleindex,orasingle performance analysis method, by itself for performance monitoring and diag- nosis,aseachcriterionhasitsmeritsandlimitations.Thebestresultsareoften xii Preface Fig. 2 Proposed framework for control-performance-monitoring-based optimisation of control loops obtainedbythecollectiveapplicationofseveralmethodsthatreflectcontrolper- formancemeasuresfromdifferentaspects.Basedonourexperiencefromappli- cationofdifferentassessmentmethodstocontrolsystemsinthesteelprocessing field,systematic proceduresforautomaticand continuouscontrol performance monitoring,maintenanceandoptimisationwillberecommended,combiningdif- ferentcontrolperformancemetricsandassessmentmethods.Guidelinesforhow toselectordeterminethespecificparameters,e.g.,modelordersandtimedelay, areworkedout.ManyimprovedandnewCPMtechniquesdevelopedbytheau- thorarepresented.Forinstance,anewframeworkandmethodfordetectionand quantification of stiction in control valves is developed based on Hammerstein modellingandestimationusingglobalsearchalgorithms.Moreover,themethod isextendedforcomprehensiveoscillationdiagnosis,i.e.,discriminatingbetween differentcausesgeneratingtheoscillation,eveninthecaseofmultiplefaults. 3. Introducing Anticipatory Control Maintenance Practices. Bridging the fields “ConditionMonitoringandDiagnosis”,“ControlPerformanceAssessmentand Monitoring”and“AutomaticControllerTuningandAdaptation”isacoreobjec- tiveof this monograph;see Fig. 2. Loop conditionmonitoringand diagnosis is neededtoinvestigatethepropertiesofcontrolloopcomponentsintermsofsignal levels,noiselevels,nonlinearitiesandequipmentconditions.Thisparticularlyin- cludes the detection of oscillations possibly generated by aggressive controller tuning, the presence of nonlinearities (e.g., static friction, dead-zone, hystere- sis), or (internal and external) disturbances. Performance assessment is used to supervisethecontrolloopsduringoperationandensurethattheymeettheperfor- mancespecifications.Failuretomeetthespecificationsshouldgiveanalert.Itis
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