Abbreviations and Acronyms...xxix

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1 Contents List of Contributors...xxv Abbreviations and Acronyms...xxix 1 Introduction... 1 Mohieddine Jelali and Biao Huang 1.1 Motivation TypicalValve-controlledLoop StictionPhenomenonandRelatedEffects Input Output Relation of Valves Under Stiction LimitCyclesduetoStiction Typical Observations in Control Loops with Sticky Valves Industrial Examples of Loops with Stiction SummaryandConclusions Part I Stiction Modelling and Oscillation Detection 2 Stiction Modelling M.A.A. Shoukat Choudhury, Nina F. Thornhill, Manabu Kano and Sirish L. Shah 2.1 Introduction Physics-based Stiction Modelling Data-driven Stiction Modelling One-parameterStictionModel Two-parameterStictionModel Choudhury s Stiction Model SimulationoftheStictionModel Kano sstictionmodel Comparison Between Choudhury s and Kano s Stiction Models Similarities Differences xvii

2 xviii Contents Comparisons Using an Industrial Example SummaryandConclusions An Alternative Stiction-modelling Approach and Comparison of Different Stiction Models Q. Peter He, Jin Wang and S. Joe Qin 3.1 Introduction He stwo-parametermodel ThreeData-drivenModels Implementation of the First-principles Model ComparisonofData-drivenModels FurtherInvestigationofValveStiction He sthree-parametermodel SimulationResults An Industrial Example SummaryandConclusions Appendix: Proof of the Equivalence Between He s Two-parameterandThree-parameterModel Detection of Oscillating Control Loops Srinivas Karra, Mohieddine Jelali, M. Nazmul Karim and Alexander Horch 4.1 Introduction Root-causes for Oscillatory Control Loops PoorProcessandControlSystemDesign Aggressive Controller Tuning Non-linearities in Control-loop Hardware External Oscillatory Disturbances Characterisation of Oscillations Auto-covarianceFunction PowerSpectrum Strength of Oscillations Techniques for Detection of Oscillations in Control Loops DetectionofSpectralPeaks Regularity of Large Enough Integral of Absolute Error Regularity of Upper and Lower IAEs and Zero-crossings Decay-ratio Approach of the Auto-correlation Function Regularity of Zero-crossings of the Auto-correlation Function SpectralEnvelopeMethod Critical Evaluation of Oscillation-detection Methods Features of Industrial Control-loop-oscillation Detection DetectionTestExamples SignalwithColouredNoise Signal with One Predominant Oscillation Signal with Dampened Oscillation

3 Contents xix Signal with Multiple Oscillations Signal with Intermittent Oscillations Comprehensive Oscillation Characterisation Industrial Case Studies Oscillating Flow Control Loop Unit-wide Oscillation Caused by a Sensor Fault Plant-wide Oscillation Caused by a Valve Fault SummaryandConclusions Part II Advances in Stiction Detection and Quantification 5 Shape-based Stiction Detection Manabu Kano, Yoshiyuki Yamashita and Hidekazu Kugemoto 5.1 Introduction MethodDescription MethodA MethodB MethodC KeyIssues SimulationResults Application to Industrial Loops SummaryandConclusions Stiction Detection Based on Cross-correlation and Signal Shape Alexander Horch 6.1 Introduction TheCross-correlationFunction Industrial Examples LoopInteractionI LoopInteractionII FlowControlLoopI FlowControlLoopII LevelControl TheoreticalExplanation Correlation for Oscillating External Disturbances TightTuning CorrelationinthePresenceofStiction Conclusions (Cross-correlation Method) StictionDetectionforIntegratingProcesses Detection in Integrating Loops Basic Idea Differentiation and Filtering SampleHistogram DistributionfortheStictionCase Distribution for the Non-stiction Case Examples LevelControlLoopwithStiction...142

4 xx Contents Level Control Loop Without Stiction LevelControlLoopwithDeadband Self-regulating Processes FlowControlLoopwithStiction Flow Control Loop Without Stiction Loops with Dominant P-control SummaryandConclusions Curve Fitting for Detecting Valve Stiction Q. Peter He and S. Joe Qin 7.1 Introduction MethodDescription Sinusoidal Fitting Triangular Fitting StictionIndex KeyIssues SimulationResults Application to Industrial Loops SummaryandConclusions A Relay-based Technique for Detection of Stiction Claudio Scali and Maurizio Rossi 8.1 Introduction TrendsofDifferentVariables MethodDescription BasicIdea StictionIndex Fitting Procedure Fitting Algorithm SimulationResults NominalCase PresenceofNoise ApplicationtoPlantData SummaryandConclusions Shape-based Stiction Detection Using Area Calculations Timothy I. Salsbury and Ashish Singhal 9.1 Introduction MethodDescription TheoreticalBasis Stiction Detection Hypothesis Test NoiseEffectsandPracticalImplementation KeyIssues SimulationResults Application to Industrial Loops

5 Contents xxi Temperature Control Loop with Stiction fromabuildingautomationsystem Temperature Control Loop with Stiction from a Pulp andpaperplant SummaryandConclusions Estimation of Valve Stiction Using Separable Least-squares and Global Search Algorithms Mohieddine Jelali 10.1 Introduction Basic Approach Identification Model Structure: Hammerstein Model LinearModel StictionModel Identification Approach SeparableLeast-squaresEstimator GlobalSearchAlgorithms KeyIssues ModelStructureSelection Time-delayEstimation Determination of Initial Parameters and Incorporation ofconstraints SimulationStudies First-order-plus-time-delayProcess IntegratingProcesswithTimeDelay Industrial Case Studies LoopCHEM25:PressureControlLoop LoopPAP2:FlowControlLoop Loop CHEM 24: Flow Control Loop with Setpoint Changes LoopPOW2:LevelControlLoop LoopPOW4:LevelControlLoop LoopMIN1:TemperatureControlLoop Loop CHEM 70: Flow Control Loop with External Disturbances SummaryandConclusions Stiction Estimation Using Constrained Optimisation and Contour Map Kwan Ho Lee, Zhengyun Ren and Biao Huang 11.1 Introduction StictionModelofControlValve GeneralConception PhysicalModelofValveSticion Kano svalve-stictionmodel Choudhury s Valve-stiction Model

6 xxii Contents He svalve-stictionmodel Existing Stiction-detection Methods Open-loop Methods Closed-loop Methods Discussion of Existing Methods Closed-loop Stiction Detection and Quantification BasicPrincipleandImportantSteps Stiction Detection and QuantificationProcedure SearchSpaceofStiction-modelParameters ConstrainedParameter-searchTechniques Advantages Stiction Detection: Identifiability Analysis Heuristic Illustration of Closed-loop Identifiability Identifiability Analysis for Closed-loop Systems withvalvestiction Simulations Industrial Applications Illustrative Industrial Examples ComparativeStudy GraphicalUserInterface SummaryandConclusions Oscillation Root-cause Detection and Quantification Under Multiple Faults Srinivas Karra and M. Nazmul Karim 12.1 Introduction Preliminaries and Brief Review of Model-based Oscillation Diagnosis Root-cause for Oscillations and Compensation Techniques Oscillation Diagnosis and Root-cause Quantification Challenges to be Addressed Overview of the Root-cause Detection and Quantification Methodology Revisiting Control-valve Characteristics Under Stiction Oscillation Detection and Diagnosis Methodology Process-model Identification Under Non-stationary Disturbances IdentificationofEARMAXModel Illustrative Example: Identification Under Non-stationary Disturbance Root-cause Detection and Quantification OP PV Model Identification Methodology Identification of Controller Transfer Function Oscillation Root-cause Detection and Quantification Methodology

7 Contents xxiii 12.6 Illustrative Example: Oscillation Diagnosis Under Various FaultySituations Stiction Oscillatory External Disturbance Aggressive Controller Tuning Stiction and Oscillatory External Disturbance Stiction and Aggressive Controller Tuning Oscillatory External Disturbance and Aggressive ControllerTuning Stiction, Aggressive Controller Tuning and Oscillatory ExternalDisturbance Industrial Case Studies ControlLoop ControlLoop ControlLoop SummaryandConclusions Comparative Study of Valve-stiction-detection Methods Mohieddine Jelali and Claudio Scali 13.1 Introduction Selected Methods Industrial Control Loops Involved in the Study ApplicationResultsandDiscussion ApplicationResults SynthesisandDiscussion Efficiency of the Techniques, Problems and Countermeasures Comparison on 20 Loops with Known Problems SelectedExamples GraphicalUserInterface Suggestions SummaryandConclusions Appendix: Tables of Results of the Comparative Study Conclusions and Future Research Challenges Biao Huang, Mohieddine Jelali and Alexander Horch 14.1 SummaryoftheBook FutureResearchChallenges Stiction Modelling Oscillation Detection StictionDetectionandEstimation StictionControl...365

8 xxiv Contents Appendix A Evaluated Industrial Control Loops Appendix B Review of Some Non-linearity and Stiction-detection Techniques B.1 BicoherenceMethod B.1.1 Non-Gaussianity Index B.1.2 Non-linearity Index B.1.3 Total Non-linearity Index B.1.4 Ellipse Fitting B.2 SurrogatesAnalysis B.2.1 SurrogateDataGeneration B.2.2 Non-linear Predictability Index References Contributor Biographies Index...389

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