Control Yokogawa

Level 1

Fundamentals Training

1

Contents

2

Topics: Slide No: • Process Control Terminology • Control Principles • Basic Control Loop

11 - 18 1 - !3

• "d#ance "d#ance Control Loop Loop !$ - 31 • Control "lgorit%m 3! - $& • Cont Contro roll Sys Syste tem m $' - ($ ($ • )*ercise (( - (

3 - 10

Process Control Terminology

3

,%at is a P.C)SS /  Any operation or sequence of operations involving involv ing a change in the substance being treated. Examples: " c%ange o+ o+ en energy state " c%ange o+ o+ co composition " c%ange o+ dimension

-

hot to cold, liquid to a chemical reaction grinding coal 

Types o+ P.C)SS ""BL): Pres Pressu sure re Spec Specif ific ic Gr Grav avit ity y of of liq liqui uid  d  F lo w Density   evel !ass "emperature #onductivity   iq iquid $nterface #omp omposi osition !oles

gas

Process Control Terminology

4

,%at is a CL.S)2 L..P /  A combination of instruments or or functions that are interconnected to measure and control a process variable with feedback.

input

PROCESS

FINALCONTROL ELEMENT

output

MEASUREMENT

CONTROLLER 

Process Control Terminology

5

,%at is a T"NS2C) •  A device that registers a non-electrical non-ele ctrical parameter (eg. (eg . process variable) and outputs a corresponding useable electrical electrical signal.  – Pressure to #apacitance  – Pressure to %esistance or m&   – "emperature to %esistance  – "emperature to m& 

• Example:  – #apacitance pressure sensor module  – Pie'o(resistive pressure sensor module  – %"D  – "hermocouple

Process Control Terminology

6

,%at is a T"NS4TT) •  A device that will translate the transducers interpretation of the measured variable into a standard transmission signal.  – ) ( *+ psi pneumatic signal   – (- mA dc electrical signal  – *(+ & dc electrical signal 

Process Control Terminology "2"NT"9) .F $-!0m" C)NT S9N"L • Lo5er installation cost  – simple6 t5isted pair 5iring

• Better noise immunity  – current #s7 #oltage

• nsensiti#e to 5ire resistance  – current #s7 #oltage

• Better suited +or %aardous locations  – intrinsic sa+ety

7

Process Control Terminology ,%at is a C.NT.LL) / • Used to keep a process variable at a desired value (set point).  – Closed loop #s7 .pen loop control

• ifference: !pen loop control has no feedback  – Control 4odes

• !"#!$$ (%inar&) • 'roportional (') • 'roportionalplusnte*ral (') • 'roportionalplusnte*ralpluserivative (')

8

Process Control Terminology

9

,%at is a S9N"L / •  An event that conve&s data from one point to another.

,%at is an N2C"T. / •  An instrument which visuall& shows the value of the variable. Example : U+,,-U+/0-U+00-U+-0-

,%at is a )C.2) / •  An instrument that makes and displa&s a continuous *raphic acoustic or ma*netic record of a measured variable. Example : 'aperless 1ecorder 2 3oko*awa  $2 3oko*awa

,%at is a 2CS / •

istributed 4ontrol 5&stem consistin* of functional inte*rated subs&stems. 6he subs&stems are connected b& a communication linka*e (e*) data busdata hi*hwa&.

Process Control Terminology ,%at is a FN"L C.NT.L )L)4)NT/ • 6he last control element in the process control loop that manipulates the process variable.  – Control al#es 7 modulates flow rate 7 operated b& actuator   – Lou#ers and 2ampers 7 operated b& pneumatic actuators  – ariale Speed 2ri#es 7 operated b& electronic control si*nals ♦

4 - 2 mA

1 0

Control Principle

1 1

Control Principle !EE"

#$%"&'

P.C)SS C.)CTN9 NT

1 2

4)"SN9 NT

O/P

PV SP

C.NT.LLN9 NT

.P)"T.

Control t%eory can be encapsulated as the matchin* of a measured variable ('8) to the plant re9uirement (5'). A controller implements a Control Algorithm so that an output signal (O/! acti"ates a correcting unit# $he ratio o% output signal (O! to input signals (&! is 'ain (!# Proportional and 1 ; < =

100 ; 9ain

<

 .

* 100;

 

Control Principle • Process ariale >P?  – the actual measurement of the state of the process

• Set Point >SP?  – the desired state of the process variable

• Control "lgorit%m  – the predefined response of the controller to '85'

• Controller .utput >.@P?  – a si*nal determined b& the control al*orithm

• .++set  – the value of '85' when the s&stem is in e9uilibrium

• 2irect "cting Controllers  – as the value of the measured variable increases the output of the controller increases.

• e#erse "cting Controllers  – as the value of the measured variable increases the output of the controller decreases.

1 3

Control Principle n%erent egulation •  A plant possesses inherent re*ulation when in the absence of a controller e9uilibrium is reestablished after a disturbance.  – For e*ample6 a tanA 5it% constant in+lo5 is in euilirium7  – T%e out+lo5 #al#e is t%en opened a little more7  – T%e out+lo5 pressure decreases as t%e tanA le#el +alls until in+lo5 again euals out+lo57  – 4anipulation o+ t%e out+lo5 #al#e result in di++erent6 uniue euilirium states7

1 4

Control Principle

1 5

nstrument Symols )*ample nstruments TT

@P 4urrentto'ressure 6ransducer 

6emperature 6ransmitter 

FC $low ndicatin* 4ontroller 

PT 'ressure 6ransmitter 

T) 6emperature Element (6hermocouple 16)

P@P

'ressureto'ressure 6ransducer 

nstrument Location ocal +ountin*

'anel $ront +ountin*

'anel 1ear or 1ack +ountin*

Control Principle

1 6

nstrument Symols Letter 2esignations

" C 2 F  L P   T 

First Letter 4easured or  4odi+ier nitiating ariale  Anal&sis User;s 4hoice User;s 4hoice ifferential $low 1ate 1atio ($raction) 4urrent (Electrical) evel 'ressure 8acuum "oise? in +easurement 5i*nal • +a& 1e9uire $ilterin* 7 +a& 1e9uire $ast1espondin* E9uipment  – Typically euires Temperature Compensation @P

FC

FT

TT

Basic Control Loop

2 2

Le#el Control Loop >n+lo5? @P

LC

T3(1 T$(1

• evel oop ssues:  – Control "t n+lo5 or .ut+lo5  – Non-Sel+ egulating

LT

Basic Control Loop

2 3

Le#el Control Loop >.ut+lo5?

LC

LT

@P

"d#ance Control Loop

2 4

,%at is C"SC"2) C.NT.L / 4onsist of one controller (primar& or master) controllin* the variable that is to be kept at a constant value and a second controller (secondar& or slave) controllin* another variable that can cause fluctuations in the first variable. 6he primar& controller positions the set point of the secondar& and it in turn manipulates the control valve.

#rimar* controller 

r -

$%4

c-

Multi-Variable Control

econdar* controller 

r @

$%4

c@

m

"isturbance 5econdar& 'rocess

'rimar& 'rocess

"d#ance Control Loop

2 5

)*ample o+ C"SC"2) C.NT.L 6he temperature of the li9uid in the vessel is controlled b& re*ulatin* the steam pressure in the acket around the vessel. 6emperature transmitter  "

6emperature controller 

+easurement !utput !easurement  Backet

!U6

8alve

SINGLE-LOOP CONTROL

Pressure transmitter 

Pressure controller 

5team

Cascade Control Loop

"d#ance Control Loop mplementing Cascade Control

2 6

"d#ance Control Loop

2 7

,%at is F))2 F.,"2 C.NT.L /  Applies to a s&stem in which a balance between suppl& and demand is achieved b& measurin* both demand potential and demand load and usin* this data to *overn suppl&. t *ives a smoother and stable control than feedback control.

Multi-Variable Control

team

!eedwater  $6 6

$6

$low controller  #, %#

+oiler   

SP

evel indicatin* controller 

SP

Feed forward

"d#ance Control Loop mplementing Feed+or5ard Control

2 8

"d#ance Control Loop

2 9

,%at is "T. C.NT.L /

 An uncontrolled flow determines a second flow so that a desired ratio is maintained between them. 6he ratio factor is set b& a ratio rela& or multipl&in* unit which would be located between the wild flow transmitter and the flow controller set point. $low % is controlled in a preset ratio to flow A.

Multi-Variable Control 'ontrolled flow/ + ild flow/ A

1atio %utput 0 A x ratio rela&

SP

1emote  set controller 

%utput 

'ontrolled flow/ + 1atio controller 

ild flow/ A

SP

%utput 

"d#ance Control Loop

3 0

)*ample o+ "T. C.NT.L PicAling Process

 Acid suppl*  5et

anual water regulator  at er 

$6 !low transmitter 

$low A

+easurement

$4 agnetic flowmeter  $low %

'ontrol valve

#ic3le tan3  /ther Application 0 !uelair ratio control s*stem on combustion e1uipment/ e.g. boilers.

"d#ance Control Loop

3 1

,%at is S)L)CT) C.NT.L / 6he more important condition between two or more candidates is selected. 6he& are used mainl& to provide protection to a piece of e9uipment which could suffer dama*e as a result of abnormal operatin* conditions.

Multi-Variable Control ow select  %#  '4 #, 

$ 5peed 4ontrol %#  #ump

%#  '4 #, 

Control "lgorit%m

• !n#!ff • +ultistep • 'roportional • nte*ral • erivative

3 2

Control "lgorit%m

3 3

.n-.++ Control t is a twoposition control merel& a switch arran*ed to be o++  (or on as re9uired) when the error is positive and on (or off as re9uired) when the error is ne*ative. Ex.. %ven 5 Alarm control.

4easured #ariale

di++erential

Controller output Time

Control "lgorit%m

3 4

4ulti-Step "ction  A controller action that ma& initiate more than two positionin* of the control valve with respect to the respective predetermined input values.                   t                u                p                                   1     n

8 ( 8 0 ' (

Time

       n                                        it     o                     i               s                o                p                    e                               l     #               a                     0

$ 3 ! 1

4ulti-step action

Time

Control "lgorit%m

3 5

Proportional "ction >P? t is the basis for the ,mode controller. 6he controller output (!#') is proportional to the difference between 'rocess 8ariable ('8) and the 5et 'oint (5'). Process oad  SP  P&  #ontroller  /utput 

.pen-loop response o+ proportional mode

Control "lgorit%m

3 6

/1P 2 6 

Proportional Proportional "ction >P? 6he Al*orithm is :

- (PV - SP) O/P ! Proportional Band

" Contant

 ('onstant is normall* 78 )

an θ

7 

θ

S ( P&  D ain D -FF # 'roportional %and

Chen a disturbance alters the process awa& from the setpoint the controller acts to restore initial conditions. n e9uilibrium o++set ('8 5' D constant) results. P&  an* controllers have a 9manual reset. his enables the operators to manipulate the 9constant term of the algorithm to eliminate offset.

"ime %ecovery time

/ffset 

SP  "ime

Control "lgorit%m Lo5 Proportional 9ain: >Closed Loop?

3 7

Control "lgorit%m Dig% Proportional 9ain: >Closed Loop?

3 8

Control "lgorit%m

3 9

ntegral "ction >?

Chilst '8 ≠ 5' the controller operates to restore e9ualit&.  As lon* as the measurement remains at the set point there is no chan*e in the output due to the inte*ral mode in the controller. 6he output of the controller chan*es at a rate proportional to the offset. 6he inte*ral time *ives indication of the stren*th of this action. t is the time taken for inte*ral action to counter the GoffsetH induced b& 'roportional Action alone.

8 easurement 

et #oint 

et #oint 

$   aI

8 %utput  ime

ntegral mode

Open-loop repone

bI

$   0 $eset ime min.rpt  a0b

ime

Proportional plus ntegral mode

Control "lgorit%m

4 0

ntegral "ction: >Closed Loop? -FF MF 5'

LF KF JF

'8 N

0F 'roportional 'lus nte*ral !utput

/F ,F @F

'roportional 1esponse

-F

F

-

@

,

/ 6ime

0

J

K

L

M

Control "lgorit%m

4 1

2eri#ati#e "ction >2?

 As the '8 chan*es the controller resists the chan*e. 6he controllers output is proportional to the rate at which the difference between the measured and desired value chan*es. 6he derivative time is an indication of this action. t is the time that the openloop PE2 response is ahead of the response due to P onl&.

8 easurement 

et #oint 

et #oint 

"  0 "erivative ime (min) "  #roportional onl* 

8 %utput (;") ime

2eri#ati#e mode

Open-loop repone

ime #roportional < "erivative

Proportional plus 2eri#ati#e mode

Control "lgorit%m

4 2

P2 "ction: >Closed Loop? -FF MF 5'

LF KF JF '8

N 0F

' !utput

/F ,F @F -F

F

-

@

,

/ 0 6ime

J

K

L

M

Control "lgorit%m

4 3

P2 Control   e=    g   n   a>     $   e    l   a4    c    )    8 2 

easurement   A

   t   u   n   p   o    t   u    i    t    i    %   s   r   r   o   e    #    l    l   o   e   o   r    l   v    t   n   a   o    ,    '

#roportional  #roportional < ;ntegral  + #roportional < ;ntegral < "erivative ime - minutes

.pen-loop response o+ t%ree-mode controller 

Control "lgorit%m P  2 Piping  nstrumentation 2ra5ing #ompressed Air Pipe #onverter  P$D I"P PIC #ontroller 

Pneumatic  #ontrol  &alve

P

PT Pressure "ransmitter  Process &essel 

Fluid Pump

4 4

Control "lgorit%m

4 5

Controller Selection 5tart tep change in valve travel 

4an offset be 3es tolerated O

Use '

Use 'onl&

4o

>?.2  8

3es s dead time excessive O

4o

s noise present O

3es

Use 'P

$eaction curve of measured variable

'  'apacit*  "ead ime

4o

ime (sec)

Control "lgorit%m

4 6

Controller "dGustment   e    l    b   a    i   r   a    8    d   e    l    l   o   r    t   n   o    4

#eriod  #-onl*  #;"

#; 

6ime Control loop )lo* .e"el $emperature Analtical ressure

Proportional band +igh (250,! .o* .o* +igh .o*

Time constant )ast (1 to 15 sec! Capacit epenent Capacit epenent suall slo* suall %ast

Derivative -e"er   arel suall ometimes ometimes

Control System "dapti#e Control

4 7

 An automatic control scheme in which the controller is pro*rammed to evaluate its own effectiveness and modif& its own control parameters to respond to d&namic conditions occurrin* in or to the process which affect the controlled variables.

Ex)

2igital Controller   ensors are run to the computers input. - ervomechanisms are connected to the computers output. - !uture changes dont re1uire re-wiring. - 'hanging control functions (#/;/ and ") and configurations (between cascade mode and feedforward mode) will be made on the computers program and not necessaril* to an* hardware.

Control System

4 8

Super#isory Control  A control strate*& where the process control computer performs s&stem control calculations and provides its output to the setpoints inputs of conventional analo* controllers. 6hese analo* controllers actuall& control the process actuators not the maincontrol computer. S SP1

477S

Super#isory Control

Controller 

"

S SP!

Controller 

"

S SP3

Controller 

"

Control System

4 9

TodayHs 2CS System  Coa*

 @. acA

 Controller   Tools +or Process "nalysis6 2iagnostics7

D, and So+t5are Filtering  4easurement

Sampled alue @. acA

 Controller 

 Tools +or Process "nalysis6 2iagnostics7

Control System

5 0

,%at is a F)L2BS / 2e+inition777  A di*ital twowa& multidrop communication link amon* intelli*ent field devices and automation s&stems. Fieldus

>.nly 2igital Signals?

P 6

Control room operator stations 

Control systems >2CS or PLC? $

Control System

5 1

Fieldus Control System ,orA Systems

Total o+ appro*imately 3(6000 de#ices >due to address limits? 7 DS)

9ate5ay Controller  D1 D1 D1

1!$

D! Bridge

2e#ices D1

D1 3! 2e#ices

D1 - 317!( =it@s DS) - 100 4 it@s >Fast )t%ernet?

D1 3! 2e#ices

Control System

5 2

Proprietary Bus

AD#ANCED CONTROL

P2 P2

P2 P2

" "

" "

 

2CS

OPTIMI$ATION

". ". $ -!0 m"

$ -!0 m"

$ -!0 m"

Control in the control room  Control

Control System

5 3

Foundation Fieldus 2e#ices CENTUM CS%&&

 Built-In Fun!tion (lo!)s

Control An*here #al'e

Transmitter CA.&O$

AI

&-

O$

PID

 

CA.O$ CA&-

AO

Control in the field with fieldbus  Control

FIELD#UE

LooA at %o5 t%e C.NT.L migrate #entral #ontrol oop

ocal #ontrol oop D#S 

#ontrol in the field 

5 4

F#S 

DD#  Digital  P$D P$D  Analog 

oop *

oop -  

 Analog 

oop *

oop -  

Digital 

P$D

P$D

oop *

oop -  

#ontrol in the device itself 

)*ercise hich defined term is closest to the description or encompasses the example given@  A.

'ontroller

!.

#rimar* element 

+.

'onverter

.

ignal  

'.

;nstrument

B.

ransducer  

".

#oint of measurement

E.

#rocess

-.

'rocess temperature increases the measurable

;.

ransmitter  

resistance in a monitored electrical circuit.

Q

R

@.

'ulsed output from a turbine meter.

Q

R

,.

Seatinected plastic moldin*.

R

Q

5 5

)*ercise /.

6emperature transmitter.

Q

0.

evice which adusts the measured value of the

5 6

R

process to the re9uirements of the operator. Q

R

J.

Element flow transmitter controller and correctin* unit. Q

K.

A pipe piece is tapped for a sample fluid.

Q

L. A device chan*es an industr& standard pneumatic standard h&draulic si*nal. Q R

R

R si*nal to an industr&

)*ercise M. dentif& the components indicated b& the Arrows.

5 7

)*ercise

5 8

hich defined term is closest to the description or encompasses the example given.  A. +. '. ". E.

'ascade control 'ontrol algorithm 'ontrol valve !eed-forward control !oundation !ieldbus

!. . B. ;.

ain %ffset   #roprietar* +us mart "evice

-F. 6he predefined response of the controller to '85'.

Q

R

--. 6he value of '85' when the s&stem is in e9uilibrium.

Q

R

Q

R

-@. 6he ratio of controllerHs output to input. Q

R

-,. t is a final control element operated b& an actuator.