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# The Fundamentals of Model Predictive Control (MPC)

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What control problems are ideal for deploying MPC and how does MPC deliver higher performance when deployed against these appropriate control challenges? Since deploying a more advanced controller costs additional money, how can you pre-qualify value and estimate if a solution seems cost justified? In this presentation, you'll learn about basic MPC Solution design and value estimation methods.

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### The Fundamentals of Model Predictive Control (MPC)

2. 2. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. • What is MPC • Is my control problem a MPC problem? And how? • What is the value of using MPC on my problem? 2 The Fundamentals of MPC
3. 3. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. A Simple MPC Problem  Goals:  Get everything wet  Keep the temperature OK  MV: Manipulated Variables  Hot water valve  Cold water valve  Constraints:  Clean by 9:00  Don’t burn (T < 100° F)  Don’t freeze (T > 70° F)  CV: Controlled Variables  Water temperature  Water flow Help ! Handle Disturbances
4. 4. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. 4 ClO2 Generation Example  Multi-variable control with disturbance rejection  Leveraging mathematical dynamic process models H2O2 Flow H2SO4 Flow NaClO3 Flow Reboiler Steam Flow Saltcake Filter Speed Production Rate G eneratorSolids H 2SO 4 Conc NaClO 3 Conc. G eneratorLevel Steam /Production Ratio G eneratorPressure Controller% O P
5. 5. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Why Use- Model Predictive Control  Plant equipment constraints are always shifting so it is difficult for plant operators to optimize a plant all the time.  MPC uses a dynamic process model to proactively control a process and optimize its performance. Heater Tube metal temperature limits Product(s) Quality Constraints Distillation hydraulic constraints Pump Constraints Pressure Limits Heating fuel Availability Constraints MPC - Good for Multiple variables, long time constants, quality control Feed quality disturbances
6. 6. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Where does MPC fit in IA MPCMPC MPC = Pavilion8 sw Advanced Process Control fitting Rockwell Automation Integrated Architecture & Logix controllers 6
7. 7. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. MPC Requirements/ Basics  Material Balance is maintained: What comes in must balance what goes out. Level or Pressure control, discharge constraints (shower drain), balance of plant.  Energy Balance is maintained: the heat that is added must balance with the heat that is removed. Temperature control, reactor duty balancing, (frequently) quality control.  Quality targets are maintained: the product being produced must be sellable, dischargeable or rejected/recycled. This includes primary products, co-products, by- products and residuals sent to the drain/utility plant. Residence time, feedstock chemistry/ratios, temp/pressure conrol.  Environmental and Safety constraints must be maintained.
8. 8. Copyright © 2014 Rockwell Automation, Inc. All Rights Reserved. Multivariable control  Decouple multivariable interactions  Handle sensitivity issues (RGA - relative gain analysis)  Maintain constraints dynamically and stably  Handle complex dynamics (inverse response)  Feed forward disturbances