Two Man Ip Control

7/30/2019 Two Man Ip Control

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©2006Fisher-Rosemount Systems, Inc.

Slide 1- 1Control Using Two Manipulated Parameters

Control Using Two Control Using Two

Manipulated Parameters Manipulated Parameters




Slide 1- 2

Process Control

Introduction – Historic Perspective

Introduction Introduction Æ Overview – Typical Examples

Æ Split-Range Control

– Concept, variations in implementation

– Setup in field vs. Splitter Block and IO for each valve.

– Using Splitter Block, Example.

Æ Valve Position Control

– Concept and typical implementation

– Setup of I-only control in implementation

– Impact of mode/status, Example.

Æ Combining Split Range and Valve Position Control

– How to implement in DeltaV

– Example

Æ Summary




Slide 1- 3

Process Control


Control Using Two Manipulated Parameters Control Using Two Manipulated Parameters Control Using Two Manipulated Parameters Æ Under specified problem

that has multiplesolutions for unlimitedoperation.

Æ Extra degree of freedomis used to achieveunique solution thatsatisfied specific controlobjective.

Æ Most commontechniques are: splitrange, valve positioncontrol.

Æ Combination of thesetechniques offer newcapability to address thisclass of problems

Controller Process

SP

Unmeasured

Disturbance

One(1) Controlled

Parameter

Two(2) Manipulated

Parameters




Slide 1- 4

Process Control


Split Range – Traditional Implementation Split Range Split Range – – Traditional Implementation Traditional Implementation Æ Sequencing of valve accomplished

through calibration of positioner,selection of actuator (A/O or A/C)

Æ Pro – Less expensive installation (1pair of wires to field and 1 I/P)

Æ Con -Difficult to initially calibrateand continuously improve to getbest gap and most constant gain.

Æ Con -Individual valves notaccessible for trouble shooting loopand actuator/valve problem.

Æ Con – The actuator, pneumaticpositioner, and I/P performanceshift with time and field conditions

Æ Con – I/P failure disables 2 valves.Replacements in the night may nothave the special settings

IP

101

TT101

TIC

101

Process

Temperature Example

4-20ma

Heating

Cooling

3-15PSI

ValvePosition(% of Span)

IP Output ( PSI )153

0

100

Cooling

Heating

A/C

A/O




Slide 1- 5

Process Control


Split Range – Traditional Implementation Split Range Split Range – – Traditional Implementation Traditional Implementation Æ Sequencing of fine and coarse

valve requires pressure switch,two solenoid valves andassociated wiring and tubing

Æ Con – Complex installation

Æ Con -Difficult to initially calibrateand continuously improve to getbest gap and most constant gain.

Æ Con -Individual valves notaccessible for trouble shootingloop and actuator/valve problem.

Æ Con – The switch, actuator,pneumatic positioner, and I/Pperformance shift with time andfield conditions

Æ Con – I/P failure disables 2valves. Replacements in thenight may not have the specialsettings

IP

102

AT102

AIC

102

Process

pH Example

4-20ma

Coarse Valve

Fine Valve

3-15PSI

A/O

pH

ValvePosition(% of Span)

I/P Output ( PSI )1530

100

Fine Valve

Coarse Valve

A/O

PS102




Slide 1- 6

Process Control


Split Range – DeltaV Implementation Split Range Split Range – – DeltaV Implementation DeltaV Implementation Æ Splitter bock is used

to implement split

range control.

Æ When using

traditional valves,

split range control

may implemented in

DeltaV Controller

using two(2) current

outputs

Æ

Split range controlmay be partially or

fully assigned to

fieldbus devices.

AI PID SPLT

AO

AO

AI PID SPLT

AO

AO




Slide 1- 7

Process Control


Split Range Control in DeltaV Split Range Control in DeltaV Split Range Control in DeltaV




Slide 1- 8

Process Control


Splitter Block Calculation Splitter Block Calculation Splitter Block Calculation




Slide 1- 9

Process Control


IN_ARRAY Parameter IN_ARRAY Parameter IN_ARRAY Parameter Æ The SP range

associated witheach output isdefined by

IN_ARRAY.Æ SP range of

outputs may bedefined to overlap

Æ The SP upper end

of range must begreater that lower end of range for each output

SP range

associatedwith OUT1

SP range

associated

with OUT2




Slide 1- 10

Process Control


OUT_ARRAY Parameter OUT_ARRAY Parameter OUT_ARRAY Parameter Æ When SP is outside

defined range, thenthe value at the end

of range is used todetermine theoutput.

Æ LOCKVALdetermines if OUT1value is held if SP isgreater that theupper end of rangedefined for OUT1.

Æ No restrictions areplaced on the outputrange.

OUT1 Range for associated SP range




Slide 1- 11

Process Control


Splitter Block Splitter Block Splitter Block

SP

0 100

0

100

0

100

0

100

100

100

0

0

OUT_1

OUT_2

LOCK_VAL “holds ”

LOCK_VAL “is zero ”

OUT_ARRAY

0 100 0 100

IN_ARRAY

0 100 0 100

OUT_ARRAY

100 0 0 100

IN_ARRAY

0 40 35 100

OUT_ARRAY

0 100 0 100

IN_ARRAY

0 40 35 100HYSTVAL




Slide 1- 12

Process Control


AI PID SPLT

AO

AO

IP

103A IP103B TT

103

FY103

TIC

103

COOLERHEATER

TT103 TIC103 FY103 IP103A

IP103B

Slaker – Heating/Cooing Example Slaker Slaker – – Heating/Cooing Example Heating/Cooing Example




Slide 1- 13

Process Control


ValvePosition

(% of Span)

TIC103 Output (% of Span)1000

0

100

Cooling (IP103B)

Heating (IP103A)

Split Range Output (FY103) Split Range Output (FY103) Split Range Output (FY103)




Slide 1- 14

Process Control


AI PID SPLT

AO

AO

IP104A

IP104B

PT104

FY104

PIC104

PT104PIC104 FY104 IP104A

IP104B

Steam Header Example Steam Header Example Steam Header Example

400# Header

1475# Header Boiler

Turbo

Generator




Slide 1- 15

Process Control


ValvePosition

(% of Span)

PIC104 Output (% of Span)1000

0

100

Valve 104A

Valve 104B

Split Range Output (FY104) - Capacity Split Range Output (FY104) Split Range Output (FY104) - - Capacity Capacity




Slide 1- 16

Process Control


Calculating Splitter SP Ranges Calculating Splitter SP Ranges Calculating Splitter SP Ranges Æ A 1% change in controller

output to the splitter shouldhave the same impact oncontrol parameter whenoperating with either valve.

Æ When manipulating thesame or similar materiale.g. steam flow to header,

then the range may becalculated based on valverating.

Æ Tests may be performed to

determine impact of eachvalve on the controlledparameter.

Example: Steam flow to Header, splitter

interfacing directly to PRV’s, no overlap

Valve 1 rating = 50kph

Valve2 rating = 150kph

Desired Splitter Span valve 1 =100*(50/(150+50)) = 25%

SP range for valve 1 = 0-25%

SP range for valve 2 = 25-100%




Slide 1- 17

Process Control


Testing Process to Determine

Splitter SP Ranges

Testing Process to Determine Testing Process to Determine

Splitter SP Ranges Splitter SP Ranges Æ With the process

at steady stateand AO’s in Automode, determinethe magnitude of change in thecontrolledparameter for a 1percent change

in each valve.Æ Calculate the

splitter SP spanand range for

each outputbased on theobservedresponse

Time

Cooling

Heating 1%

1%

1.1degF 2.2degF

Desired Splitter Span cooling valve =

100*(2.2/(1.1+2.2)) = 66%

SP range for cooling valve = 0-66%

SP range for heating valve = 66-100%

Controlled

Temperature

Example: Slaker feed temperature controlled

using heating and cooling valves




Slide 1- 18

Process Control


Example – Split Range Example Example – – Split Range Split Range




Slide 1- 19

Process Control


Response to SP Change – Split Range

Output To Large Valve/Small Valve

Response to SP Change Response to SP Change – – Split Range Split Range

Output To Large Valve/Small Valve Output To Large Valve/Small Valve

SmallValve

LargeValve

PID OUT

SP

PV




Slide 1- 20

Process Control


Split Range – Strengths and Weaknesses Split Range Split Range – – Strengths and Weaknesses Strengths and Weaknesses Æ Pro - Process operation in simplified since two actuators

are treated as one control manipulated parameter.

Æ

Pro – immediate change in target actuator position can beachieved over the entire operating range independent of the size of change in the splitter SP

Æ Con – To achieve stable control over the entire operating

range, controller tuning must be established based on theslower responding manipulated parameter.

Æ Con- Does not take advantage of difference in resolutionof actuator e.g. fine vs. coarse valve.

Æ Valve position control may be used in place of split rangecontrol when there are differences in dynamic response or resolution in actuators.




Slide 1- 21

Process Control


Valve Position Control – Traditional

Implementation

Valve Position Control Valve Position Control – – Traditional Traditional

Implementation Implementation

IP106A

AT106

AIC106

Process

Æ PID control isimplemented using theactuator with finer resolution or fastest

impact on controlledparameter

Æ The actuator withcoarse resolution or slower impact on the

controlled parameter isadjusted by an I-onlycontroller to maintainthe long term output of the PID controller at agiven target

Æ I-Only controller must bedisabled when the PIDcontroller is not in an

Automatic mode.

pH Example

Fine Valve

A/O

ZC106

IP106B

Coarse

Valve

I-Only

Controller

Mode

Target

Valve

Position

Time

pH

Fine Valve

Coarse Valve

Target Valve

Position





©2006Fisher-Rosemount Systems, Inc.Slide 1- 23

Process Control


Valve Position Control in DeltaV Valve Position Control in DeltaV Valve Position Control in DeltaV Æ Actuator with fastest

impact or highestresolution is used to

maintain thecontrolled parameter at setpoint.

Æ The OUT of the PIDused for control is

wired to IN on thePID block used for I-Only regulation of slower responding or coarse resolution.

PID configured for I-

Only control




Process Control


Configuring PID for I-Only Control Configuring PID for I Configuring PID for I - - Only Control Only Control Æ The STRUCTURE

parameter should beconfigured for “I actionon Error, D action on

PV”Æ The GAIN should be

set to 1 to allow normaltuning of RESET (eventhough proportional

action is notimplemented.

Æ RESET should be setsignificantly slower than that the product of

the PID gain and resettime used for controle.g. 5X slower




Process ControlIntroduction – Historic Perspective

AI PIDAO

IP107A

IP

107B

FT107

FIC107

FT107FIC107

IP107A

Precise Flow Using Big/Small Valve Precise Flow Using Big/Small Valve Precise Flow Using Big/Small Valve

ZC107

I-Only AOIP107B

ZC

107





Example -Boiler BTU Demand Example Example - - Boiler BTU Demand Boiler BTU Demand

AI PID AOFT109B

FIC109IP109A

ZC109

I-Only AOIP109B

ZC109

FT109A

IP109B

FIC109

FT109B

IP109A

FY109

Low BTU – Waste Fuel

HI BTU Fuel Boiler

BTU Demand

AIFT109A

SUM

FY109





Example –Reformer Air Demand Example Example – – Reformer Air Demand Reformer Air Demand

ZC110

AI PID AOFT110

FIC110IP110

ZC110

I-Only AOSC110

FIC110

FT110

SC110

Air

Machine

Secondary

Reformer

Total Air

Demand

IP110





Example – Valve Position Control Example Example – – Valve Position Control Valve Position Control





Response to SP Change - Valve Position

Control with Large Valve/Small Valve

Response to SP Change Response to SP Change - - Valve Position Valve Position

Control with Large Valve/Small Valve Control with Large Valve/Small Valve Æ Target

position for fine valve is

30%.

Æ When thefine valvesaturates,

thenresponse islimited to bereset of theI-Only

control

Fine Valve

Coarse Valve

SP

PV

Limited





Valve Position Control – Strengths and

Weaknesses

Valve Position Control Valve Position Control – – Strengths and Strengths and

Weaknesses Weaknesses Æ Pro – Immediate control response is based on actuator with finest

resolution and/or faster impact on controlled parameter.

Æ Pro – Actuator with coarse resolution or slower impact on controlled

parameter is automatically adjusted to maintain the output of thecontroller output long term at a specified operating point.

Æ Con – The controller output may become limited in response to alarge disturbance or setpoint change. For this case, the dynamic

response becomes limited by the slower tuning of the I-onlycontroller.

Æ The features of split range control and valve position control may becombined to provide immediate response to large changes indemand while retaining the features of valve position control for normal changes.





Combining the Best Features of

Split Range and Valve Position Control

Combining the Best Features of Combining the Best Features of

Split Range and Valve Position Control Split Range and Valve Position Control Æ A composite

Block can becreated that

combines thefeatures of splitrange and valveposition control

Æ Support for BKCAL_IN andBKCAL_OUTcan beimplemented to

providebumplesstransfer





Composite Algorithm Composite Algorithm Composite Algorithm

Filter

CAS_IN

MODE

SP

x +

x

x

T

ScalingRANGESPAN

NORMAL

OUT_1

OUT_2

BKCAL_OUT

BKCAL_IN1

BKCAL_IN2Balance Calculation

-

-FILTER_TC





Composite Implementation Composite Implementation Composite Implementation Æ Parameters that

must be configureare: FILTER_TC,SPAN (of SP),

RANGE (of OUT1), andNORMAL(desired position )

Æ The FILTER_TC

should beconfigured similar to the reset timeof the I-OnlyController that

would be used for valve positioncontrol.





Demo – Composite Combining Valve

Position and Split Range Control

Demo Demo – – Composite Combining Valve Composite Combining Valve

Position and Split Range Control Position and Split Range Control





Example: Response to SP Change Example: Response to SP Change Example: Response to SP Change Æ For small

changes in SP or load disturbance,the response is

similar to thatprovided byvalve positioncontrol

Æ For largechanges in SP or load disturbance,the immediateresponse is

similar to splitrange control

SP, PV

OUT of

PID

Fine

Valve

Coarse

Valve

Small change Large change





Summary Summary Summary Æ Split range control allows fully dynamic

response to major setpoint of load

disturbance changes.Æ Valve position control may be used to takes

advantage of any difference in controlresponse or resolution in the manipulated

parameters.

Æ A composite block has been demonstratedthat combines the best features of split range

and valve position control.

Documents

Two Man Ip Control