Fieldbus Foundation India Committee. Control In the Field

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Moses Riley
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Fieldbus Foundation India Committee Control In the Field Date : 9 December 2011 Time : 9.00 to 17.

1 Fieldbus Foundation India Committee Control In the Field Date : 9 December 2011 Time : 9.00 to hrs Venue : Hotel Express Residency Jamnagar, India Presented by : Jigish Jepal ID : jigish.jepal@in.yokogawa.com 1

2 Outline Trend observed Process Integrity and control in the field Some of the installations where control in the field is implemented Significant aspects of control in the field MRPL projects Concerns of Control in Host System and Control in the Field Few applications using function blocks in field devices Pointes to watch out Further references 2

3 Trend Observed Started with monitoring loops only Subsequently simple control (only PID block execution in field) taken in the field Gaining confidence on FF technology, simple calculations such as ratio, multiplication etc, are also executed in the field. Users have transferred control from host to the field, but not from field to DCS

4 Process Integrity and Control in the Field Control in the field enables truly distributed control and maintains Single Loop Integrity Network Management and Link Active Schedule maintains high network availability 4

5 Control in the field concept All function blocks control logic are implemented in the field devices This control concept would be ideal as - it minimizes communication traffic - control is not affected even in case of H1 card failure - Host control system execution time and I/O scan rate do not affect control performance. 5

6 Some installations where Control in the Field is implemented Shell Sakhalin (Simple loops) Shell Malampaya MRPL (ISOM) Mangalore, India BORL Bina, India MRPL (GOHDS) Mangalore, India HMEL Bhatinda, India MRPL-Phase-III Mangalore, India (under commissioning) BCPL Assam, India (Under execution) so on.the list is big and growing. Going back in the history, we find two customers, one in Brazil and one in Japan implemented control in the field in

7 MRPL projects Project : ISOM Year of commissioning : 2006 No. of FF devices : ~ 600 No. of FF close loops : ~ 130 Control assignment : Every control is important. PID executed in the field devices as long as possible, including cascade loops. For loops requiring complex calculations or many function blocks, PID executed in the DCS. Key point-1 : Control in the field helped achieving desired control cycle without significant reduction in devices per segment. Key point-2 : Being first FF project, though the implemented design was able to avoid loading on DCS system on account of execution of control cycle of 500 msec and less, the DCS was designed to take care of control. 7

8 MRPL projects Contd. Project : GOHDS Year of commissioning : 2010 No. of FF devices : ~ 100 No. of FF close loops : ~ 10 Control assignment : PID executed in the field devices as long as possible, including cascade loops. For loops requiring complex calculations or many function blocks, PID executed in the DCS. Key point : Though control cycle was not very important in this case, because of good experience of ISOM project, implemented control in the field. 8

9 MRPL projects Contd. Project : Phase-II expansion Year of commissioning : Under execution No. of FF devices : ~ No. of FF close loops : ~ 2900 Control assignment : All FF control loops shall have control in the field as long as possible, except for interactive loops with other segments. Simple calculation such as ratio, multiplication involving one arithmetic function shall be executed in fieldbus segment. For single cascade/ split control loops the master control shall be executed at transmitters and slave control at Positioner. 9

10 MRPL projects Contd. More than 90% of the control is in the field. No significant difference observed in performance between control in the field and control in the DCS. 10

11 Concerns of Control in Host System and Control in the Field (Compiled after discussions with various users and PMCs) 11

12 Flexibility Control in the Host Control in the Field Remarks Large number of blocks in DCS gives flexibility of implementing control strategy. Function blocks available in new generation field devices can implement most of the control logics. Next few slides mention various function blocks defined by Fieldbus Foundation and availability in market. 12

13 Standard Function Blocks Analog Input Analog Output Bias Flexibility- Contd. Control Selector Discrete Input Discrete Output Manual Loader Proportional/Derivative Control Proportional/Integral/Derivative Control Ratio Function Blocks defined by Fieldbus Foundation Advanced Function Blocks Pulse Input Complex AO Complex DO Step Output PID Device Control Set Point Ramp Splitter Input Selector Signal Characterizer Dead Time Calculate Lead/Lag Arithmetic Integrator Timer Analog Alarm Discrete Alarm Analog Human Interface Discrete Human Interface Additional Function Blocks Multiple Analog Input Multiple Analog Output Multiple Discrete Input Multiple Discrete Output Flexible Function Blocks IEC1131 logic SIF Function Blocks SIF Analog Input SIF Digital Output Not all of these Function Blocks are available for use in all field devices, and some are not available and/or do not yet have interoperability tests Check for registered function blocks. 13

14 Flexibility- Contd. Availability of function blocks Positioners (desired- as many as required in implementation or as desired to supplement field device) Manufacturer / Function block PID AO DI DO AR IT IS OS Fisher Dresser Flow server Metso Samsung Siemens 1 1 Tyco 1 1 Yokogawa Note : Above is indicative. Refer latest specifications of each manufacturer 14

15 Flexibility- Contd. Availability of function blocks - Pressure Transmitters (desired- PID,AR (e.g. for compensation, ratio), IT(for flow), SC(e.g. for volume of spherical tank)) Manufacturer / Function block PID DI DO AR IT IS SC Yokogawa Emerson Honeywell 1 ABB Fuji E+H Note : Above is indicative. Refer latest specifications of each manufacturer 15

16 Flexibility- Contd. Availability of function blocks Flow meters (desired- PID, AR (e.g. for compensation, ratio), IT) Manufacturer / Function block PID DI DO AR IT IS SC Yokogawa-Vortex Yokogawa-Coriolis 1 2 Yokogawa-Mag Emerson-Vortex Emerson-Coriolis 1 1 Emerson-Mag E+H-Vortex 1 E+H-Coriolis E+H-Mag Krohne-Coriolis 1 3 Krohne-Mag 1 2 Note : Above is indicative. Refer latest specifications of each manufacturer 16

17 Flexibility- Contd. Availability of function blocks Segment indicator (desired- add-on function blocks in a segment in addition to indication) Manufacturer / Function block PID DI DO AR IT IS SC Yokogawa Emerson E+H ABB Beka 2 Note : Above is indicative. Refer latest specifications of each manufacturer 17

18 DI-DO handling Control in the Host Control in the Field Remarks DI-DO in common sense and in case of Foundation Fieldbus are different. They are not mere switches. In Fieldbus they are also like any other function block having various attributes. Implementing DI-DO logic is easy in host system. DI-DO blocks are available from P&F, R.Stahl and Stonel. Use transmitters instead of switches. Switches are not reliable. Measuring devices are more reliable and offers flexibility. Infact many users have replaced switched with measuring devices. Number of physical DI- DO connection per block are limited. Hence, as of now complicated sequence of actions /logic need to be implemented in Hosts system. Such logics are primarily required in batch processes. Continuous running plant requirement can be met by available DI-DO blocks most of the times. Electrical control (Motor, VFD) remains a concern. 18

19 Complicated Calculations Control in the Host Control in the Field Remarks Calculations can be performed in HOST easily. Calculation blocks like AR, SC blocks are available in field devices. 19

20 Inconsistent Parameter Naming Control in the Host Control in the Field Remarks Parameter naming in DCS and Field device are not consistent, which might lead to confusion. Different naming helps in easy identification of control in field. No confusion. 20

21 Inconsistent Parameter Naming Control in the Host Control in the Field Remarks Control algorithm may differ from manufacturer to manufacturer. Field bus foundation has defined several function blocks. Input and outputs of these blocks are defined. Internal algorithm is left to manufacturers. As long as the block meets application requirement, internal algorithm would not matter. A block not meeting laid specification would not be registered. Check for registered function block. Replacing a device with same make, model and DD revisions, would not require PID tuning again. Art of tuning PID helps if device replaced with other make. 21

22 Asynchronous Host system execution w.r.t. macro cycle Control in the Host Control in the Field Remarks Asynchronous DCS and FF segment update leads to longer and variable latencies. In case of control in the field, since function blocks are executed in same macro cycle and execution of function blocks is precisely scheduled, there is no latency. Synchronous control has following two major advantages : - Much tighter control - Reduces loading on the Host controller. This has further following advantages - less number of host controllers, cabinets and power supplies. Small foot print and reduced HVAC load. (Reduced CAPEX.) - Flexibility of adding more loops in future without addition of host system controller, unless the 22 expansion quite big.

23 Asynchronous Host system execution w.r.t. macro cycle Control in the Host Control in the Field Remarks High reliability and availability of the process with control in the field can reduce unplanned incidents and provide tighter control. Reduced OPEX. 23

24 Asynchronous Host system execution w.r.t. macro cycle Control in the Host Control in the Field Remarks Continuous Control Functionality even if the H1 card fails. Operators can t monitor and control processes as per regular procedures. 24

25 Few applications using function blocks in field devices 25

26 Signal Characterizer- SC Convert the values of input signals according to a line-segment function. The line-segment function is created using 21 points of the X/Y coordinates specified by the user. Typical Application Spherical liquid tank volume content calculation from level measurement 26

27 Arithmatic (AR) function block Typically 10 different types of arithmatic calculations can be performed on three inputs. Typical Uses Numerous 27

28 Combination of Arithmatic (AR) and Signal Characterizer (SC) function blocks Typical Application Calorie flow compensation AI_1: Inlet temperature, AI_2: Outlet temperature, AI_3: Flow rate SC: Corrects the inlet and outlet temperatures. AR: Calculates a calorie flow rate on the basis of the difference between the corrected inlet and outlet temperatures. 28

Combination of Control (PID) and Signal Characterizer (SC) function blocks Typical Application Input Control for ph control It is very difficult to control ph.

29 Combination of Control (PID) and Signal Characterizer (SC) function blocks Typical Application Input Control for ph control It is very difficult to control ph. It requires low gain near 7 because of quickly changing reaction rate near that point and high gain towards ends. Above graph gives variable gain helping stable ph control. 29

30 Points to watch out Opt for fully loaded devices. Some of the function blocks might not be used every where. But opting for them would help reducing inventory. Additionally, it shall give flexibility in implementing various control philosophies. Check for enough VCRs availability in the field devices. Select appropriate faceplate updates so as to reduce bus traffic. Though not a concern most of the times, check for registered function blocks to have true interoperability. Recommend to have LM (link master) function in H1 card and positioner. Recommend to have PID block execution in positioner. In case of cascade control, both PIDs can be executed in positioner or one PID can be executed in positioner and other in field measuring device. Segment indicator can be used beyond its basic function of indication. It can provide add-on function blocks in field devices. 30

31 Further references ARC has published a white paper on Control in the field. It describes certain tests conducted, results of the tests and applications where control in field is very useful. The paper is available at es/documents/white_paper_control_inthe_field_arc.pdf. Section 4.3, and of AG-181 (System Engineering Guide) Rev

32 Thank you very much for your attention 32

Foundation Fieldbus Control in the Field (CIF)

Foundation Fieldbus Control in the Field (CIF) Name : Harendra G. Mistry Job Title : Chief Engineer Company : Tecnimont ICB FFIC : Automation 2011 Mumbai Foundation Fieldbus Technology Benefits Benefits