Addressing control applications using wireless hart devices

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Many WirelessHART transmitter applications require that the measurement valve be used in closed loop Control. The PIDPlus capability introduced in DeltaV v11.3 enables robust control using WirelessHART measurements. A PIDPlus enhancement in DeltaV v12.3 further improves the response for setpoint changes. Details of the PIDPlus and field results using WirelessHART transmitters and PIDPlus are presented in the workshop.

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Addressing control applications using wireless hart devices

  1. 1. Addressing Control Applications Using WirelessHART DevicesMarty Zielinski - Director of HART and Fieldbus Technology Mark Nixon – Director, ResearchTerry Blevins – Principal Technologist
  2. 2. Presenters  Marty Zielinski  Terry Blevins  Mark Nixon
  3. 3. Introduction The PIDPlus capability in DeltaV may be used to implement closed loop control using WirelessHART devices. In this workshop we address  Wireless Impact on Control  PIDPlus for Control Using Wireless Measurements  Performance Comparison to Wired Transmitter  Addressing Lost Communications  Test results – Field Installations The PIDPlus may be used with slow and variable communication updates
  4. 4. Challenge – Control Using WirelessHART  Transmitter power consumption may be minimized by reducing the number of times the measurement value is communicated.  Conventional PID execution synchronizes the measurement value with control action, by over-sampling the measurement by a factor of 2-10X.  The rule of thumb to minimize control variation is to have feedback control executed 4X to 10X times faster than the process response time (process time constant plus process delay).  The conventional PID design (i.e., difference equation and z- transform) assumes that a new measurement value is available at each execution and that control is executed on a fixed periodic basis.
  5. 5. Conventional Approach – OverSampling of Measurement Process Output 63% of Change O Time Constant ( ) Deadtime (TD ) Process Input I Control Execution New Measurement Available
  6. 6. Conventional PID - Impact of Wireless  The underlying assumption in traditional control design is that the PID is executed on a periodic basis 4X-10X times over the process response time .  When the measurement update is variable or updated less frequently, the calculated reset action may not be appropriate.  If control action is only executed when a new measurement is communicated, this could result in a delayed control response to setpoint changes and feedforward action on measured disturbances. Conventional PID Design
  7. 7. Emerson’s WirelessHART Solution Power consumption of the wireless device is reduced by transmitting the measurement value only as often as required to allow control action to correct for unmeasured disturbances. The PID may be configured to execute much faster than the measurement value is communicated. The PIDPlus is designed to automatically compensate for the slower measurement update and any variation in measurement update rates. Tuning of the PIDPlus is based strictly on the process dynamics independent of the measurement update rate and is not impacted by variations in measurement update.
  8. 8. Conventional PID - Impact of Wireless  The underlying assumption in traditional control design is that the PID is executed on a periodic basis 4X-10X times over the process response time .  When the measurement update is variable or updated less frequently, the calculated reset action may not be appropriate.  If control action is only executed when a new measurement is communicated, this could result in a delayed control response to setpoint changes and feedforward action on measured disturbances. Conventional PID Design
  9. 9. PIDPlus for WirelessHART Communications  To provide the best control for slow or variable measurement update rates, the PID must be modified to reflect the reset contribution for the expected process response since the last measurement update.  Control execution is set faster than measurement update. This permits immediate action on setpoint change and update in the faceplate.  PIDPlus is a standard feature of DeltaV v11.3 (released 2010) PIDPlus Design in DeltaV v11.3
  10. 10. PIDPlus Reset (Integral) CalculationThe filter output used in the positive feedback network is calculated in thefollowing manner when a new measurement is received.PIDPlus tuning is based on the process dynamic (e.g. RESET= processtime constant plus deadtime); PIDPlus reset automatically compensatesfor slow updates and variations in the measurement update rate. Nochange in GAIN is required for varying update rate.
  11. 11. PIDPlus Modification for Setpoint Change Automatic compensation for setpoint change; measurement update rate. No need to modify tuning as sample rate changes No Yes PIDPlus –DeltaV v12.3 release in 2012
  12. 12. PIDPlus Using Wireless Transmitter vs.Conventional PID and Wired Transmitter Lambda Tuning ʎ = 1.0 Variable communication Update Rate Control Setpoint PIDPlus Measurement PID PIDPlus Control Output PID Unmeasured Disturbance
  13. 13. CONTROL PERFORMANCE DIFFERENCE  Communications transmissions are reduced by over 96 % using slower communication update rates.  The impact of slower updates and variations in measurement updates on control performance as measured by Integral of Absolute Error (IAE) is minimized through the use of PIDPlus for wireless communication. Communications/Control Number of IAE Communications Periodic/standard PI Controller 692 123 Update Using Wireless 25 159 communication/ PI Control
  14. 14. PIDPlus - Modified Derivative Action No Yes
  15. 15. PID Performance for Lost Communications  The Conventional PID provides poor dynamic response when wireless communications are lost.  The PIDPlus improves the dynamic response under these conditions
  16. 16. Wireless Communication Loss –During Setpoint Change Setpoint PIDPlus Control Measurement PID PIDPlus Control Output PID Communication Loss
  17. 17. Wireless Communication Loss –During Process Disturbance PIDPlus Setpoint Control Measurement PID PIDPlus Control Output PID Communication Loss
  18. 18. Testing PIDPlus –Communication’s Setup For testing purposes, the WirelessHART communications and the process can be dynamically simulated in a DeltaV module for PID and PIDPlus control. Communication setup is defined by the “Transmission” composite block.
  19. 19. Installation at Broadley James  Portable Hyclone 100 liter disposable bioreactor  Rosemount WirelessHART gateway and transmitters for measurement and control of pH and temperature. Pressure monitored  BioNet is based on the DeltaV Control system.
  20. 20. Installation at Broadley James (Cont)  Detail view of Rosemount pH WirelessHART Transmitter.  Battery powered – 3 to 5 year battery life expected for this application.
  21. 21. Broadley James Bioreactor Setup VSD VSD Media 37 oC VSD Inoculums TC TT 41-7 41-7 VSD Glutamine VSD VSD Bicarbonate Glucose Heater 7.0 pH AY AC AT AT Splitter AC 41-1 41-1 41-1 41-4s1 41-4s1 0.002 g/L pH Glucose 2.0 g/L AC AT AT AC 41-2 41-2 41-4s2 41-4s2 DO Glutamine 2.0 g/L AT AT AT 41-5x1 41-5x2 Bioreactor 41-6 Viable Dead Product Cells Cells CO2 MFC LT 41-14 AY Level Splitter VSD 41-2 O2 MFC Drain Air MFC
  22. 22. Example - Automatically Identified TemperatureDynamics Using DeltaV Insight DeltaV Insight – Standard Since DeltaV v9.3
  23. 23. Wireless Temperature Loop Test Results
  24. 24. Wireless pH Loop Test Results
  25. 25. Elimination of Ground Noise Spikes Requirement: Tight pH control via 0.001 pH wireless resolution setting Temperature compensated wireless pH controlling at 6.9 pH set point Wired pH ground noise spike
  26. 26. Separations Research Program,University of Texas at Austin  The Separations Research Program was established at the J.J. Pickle Research Campus in 1984  This cooperative industry/university program performs fundamental research of interest to chemical, biotechnological, petroleum refining, gas processing, pharmaceutical, and food companies.  CO2 removal from stack gas is a focus project for which WirelessHART transmitters were installed for pressure and steam flow control
  27. 27. WirelessHART Transmitter  Standard WirelessHART pressure and flow transmitters were installed to demonstrate and test control using WirelessHART.  Standard WirelessHART pH transmitters are used to support studies associated with CO2 removal from stack gases.  Standard WirelessHART multi- element temperature transmitters are used to monitor absorber and stripper temperatures.
  28. 28. Steam Flow To Stripper Heater
  29. 29. Column Pressure Control
  30. 30. PC215 On-line Column Pressure Control  The same dynamic control Wired Measurement response was Used in Control observed for SP changes  Original plant PID tuning was used for both wired and wireless control GAIN=2.5 RESET=4 RATE=1 Wireless Measurement Used in Control
  31. 31. Control Performance – Wired vs Wireless  Comparable control as measured by IAE LOOP FIC202 PC215 FIC202 PC215 was achieved using Selected Input Wired Wired Wireless Wireless WirelessHART Measurements and IAE 9134 145 10645 198 PIDPlus vs. control with wired Number of 13655 6649 1184 912 measurements and Communication PID. Test Time (sec) 6830 6829 5926 5925  The number of Test 1 Test 2 measurement samples with WirelessHART vs Wired transmitter was reduced by a factor of 10X for flow control and 6X for pressure control – accounting for differences in test duration.
  32. 32. Separations Research Program,University of Texas at Austin  The Separations Research Program was established at the J.J. Pickle Research Campus in 1984  This cooperative industry/university program performs fundamental research of interest to chemical, biotechnological, petroleum refining, gas processing, pharmaceutical, and food companies.  CO2 removal from stack gas is a focus project for which WirelessHART transmitters were installed for pressure and steam flow control
  33. 33. Current Product: Discrete Control Video
  34. 34. Future Product:4300 Series Wireless On/Off Control Release planned for the end of 2012 Currently in 7 End User Field Trials Sites  7 different applications  6 industrial market segments
  35. 35. Business Results Achieved  The PIDPlus allows WirelessHART devices to be used for closed loop control of quality parameters that currently may not be available in the control system.  The reduction in process variability achieved through closed loop control may lead to improved process operation e.g. reduction in product quality variation, improved efficiency.  Field installations have documented robust control performance using the PIDPlus with WirelessHART transmitters. The results were shown for control of liquid flow, gas pressure, pH and temperature.
  36. 36. Summary WirelessHART measurements may be used in closed loop control applications. – Slower reporting minimizes power consumption PIDPlus is a standard feature of DeltaV and works with standard WirelessHART devices. – Standard DeltaV Tools support Simulation and Tuning The performance of PIDPlus in a wireless control network is comparable to PID with wired inputs – PIDPlus handles lost communications better than conventional PID. PIDPlus tuning depends only upon process dynamics, not on wireless update rate
  37. 37. Where To Get More Information  PID Advances in Industrial Control, IFAC Conference on Advances in PID Control PID12, Brescia, Italy, 28-30 March 2012 http://pid12.ing.unibs.it/sp_blevins.html  DeltaV v11 PID Enhancements for Wireless, DeltaV Whitepaper, August, 2010 http://www2.emersonprocess.com/siteadmincenter/PM%20DeltaV%20Documents/Whitepap ers/WP_DeltaV%20PID%20Enhancements%20for%20Wireless.pdf  WirelessHART Successfully Handles Control, Chemical Processing, January, 2011 http://www2.emersonprocess.com/siteadmincenter/PM%20Articles/WirelessHART%20Succ essfully%20Handles%20Control.pdf  Wireless – Overcoming Challenges of PID Control& Analyzer Applications, InTech, July/August, 2010 http://www.isa.org/InTechTemplate.cfm?template=/ContentManagement/ContentDisplay.cfm &ContentID=83041  PIDPlus An Enhanced PID Control Algorithm for Wireless Automation, AS-74.3199 Wireless Automation, Aalto University, Finland http://autsys.tkk.fi/intranet/as-0.3200/attach/S09- 19/loppuraportti.pdf  Incorporating Wireless Devices into Single-Use Disposable Bioreactor Design, 2009 Dhirubhai Ambani Life Sciences Symposium http://www.modelingandcontrol.com/Wireless- Devices-in-Single-Use-Bioreactors.pdf  Improving PID Control with Unreliable Communications, ISA EXPO Technical Conference, 2006. http://www.automation.com/pdf_articles/10_improving_pid.pdf  Similarity-based Traffic Reduction to Increase Battery Life in a Wireless Process Control Network, ISA EXPO2005, Houston, TX www.cs.utexas.edu/~sjp/publications/isa06.doc

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