重慶大學(xué)-過程控制-process-control-中文-翻譯-第十章

會(huì)計(jì)學(xué)1Multiloop

SystemsOutlineImproving

（disturbance

rejection干擾抑制)performancecascade

control級(jí)聯(lián)控制feedforward

control,前饋控制ratio

control,and比例控制

time

delay

compensation時(shí)間延遲補(bǔ)償with

Smith

predictor.smith預(yù)估補(bǔ)償2第1頁/共47頁Multiloop

SystemsImproving

the

DR

PerformanceCascade

Control■Control

of

afurnace

temperature；爐溫DR:

Disturbance

Rejection第2頁/共47頁3TT

TCTspMultiloop

SystemsImproving

the

DR干擾抑制

performanceS-loop

control

solution單環(huán)開環(huán)控制1.

measure

T

by

TT,compute

p

by

TC,send

the

p

to

the

valve第3頁/共47頁4Multiloop

SystemsCascade

ControlMotivation

of動(dòng)機(jī)Cascade

ControlIf

fluctuation波動(dòng)in

the

fuel

gas

flow

rate燃?xì)饬魉賢he

system

will

not

counter計(jì)數(shù)the

disturbance

unthe

controller

senses

that感知the

temperature

hasdeviated

From偏離the

set

point

(Tsp)5第4頁/共47頁Multiloop

SystemsCascade

ControlCascade

control

solutionIt

consisting

of包含:master

(primary)

loop

slave

(secondary)loopTT:

temperature

transducer溫度傳感器FT:flow

transducerTC:

temperature

controllerFC:

fuel

gas

controllerTwo

measured

variablesdisturbance

is

now

in

slave

loop副回路第5頁/共47頁6Multiloop

SystemsCascade

ControlCascade

control

solutionTC

in

master-loop

sends

its

signal

to

slave-loop副in

terms

of依據(jù)the

desired

flow

rate(casual

relation)the

signal

is

the

set

point

of

the

secondary

flow

controlleFC

in

slave

loop

adjusts

the

regulating

valve調(diào)節(jié)閥FC

compares

the

desired

and

measured

fuel

gas

flow

ratesresponding

immed第i6頁at/共e4l7y頁to

fluctuations

in

the

fuel

gas

flo 立即對(duì)波動(dòng)的燃?xì)馑俾首龀龇磻?yīng)7to

ensure

that

the

proper

amount

of數(shù)量的fuel

is

delivered.Multiloop

SystemsCascade

ControlCascade

Design

Criteria設(shè)計(jì)標(biāo)準(zhǔn)Cascade

is

desired

whensingle-loop

performance

unacceptablea

measured

variable

is

available測(cè)量值可用A

secondary

variable次要變量mustIndicate指出the

occurrence

of發(fā)生的an

important

disturbancehave

a

causal

relationship因果關(guān)系from

primary

to

secondary(cause

→

effect)第7頁/共47頁have

a

faster

response

than

the

primary8Multiloop

SystemsCascade

ControlCascade

Control

SolutionReducing

the

block

diagram方塊圖Setting

G

=m1G

=1m2where9第8頁/共47頁Multiloop

SystemsCascade

ControlReducing

the

block

diagramFrom

the

reducedblock

diagramE=R-C第9頁/共47頁10Multiloop

Systemsop

charaCascade

ControlCascade

control

solutionThe

closed-lo cteristic

polynomial特征多Comments

on

the

slave-loopreducing

disturbance

in

the

manipulated

variable被控變量減少來自被控變量的干擾.accomplish

a

faster

response

in

the

valve,make

the

system

more

stable第10頁/共47頁11Multiloop

SystemsCascade

ControlExample

1:

the

furnace

temperature

controlthe

master

loop

uses

a

PI

controller,the

slave

loop

uses

a

p-controller,with

the

first

order

functions第11頁/共47頁12Multiloop

Systemswheresubstituting

GL

=

KL/(Ls+1)

into

GCascade

ControlExample

1.

the

furnace

temperature

controlProblem

(a):

choosing

Kc2

properly

for

better

performanceSolution:Substituting取代

Gc2

=

Kc2

and

Gv

=

Kv/(

vs+1)

into

G*v13第12頁/共47頁Multiloop

Systems1.K*v1,

more

effective

change

inmanipulated

variable,2K*L0,

manipulated

variable

is

less

sensitive

tochanges

in

load,操縱變量對(duì)負(fù)載的變化敏感度降低3*vsmaller,

faster

response

ofthe

regulating

valve調(diào)節(jié)閥Cascade

ControlExample

1.

the

furnace

temperature

controlProblem

(a):

choosing

Kc2

properly

for

better

performanceas

the

proportional

gain

Kc2

becomes

larger第13頁/共47頁14Multiloop

SystemsCascade

ControlExample

1.

the

furnace

temperature

control*Problem

(b):

find

Kc2

while

v

=

0.1v*v=0.1

s,

we

havethusSolutio

n?with

Kv=0.5,參考方程v=1

s,

and15slave

loop

has

a

10%offset

with

respective

to

the

desired

set

point

changes

in

thesecondary

controller.次循環(huán)在二級(jí)控制器的設(shè)定點(diǎn)有10％的偏移變化第14頁/共47頁Multiloop

SystemsCascade

ControlExample

1.

the

furnace

temperature

control Problem(c):Now

that既然

certainly

an

offset偏移

in

the

inner

loop,why

do

we

stay

with繼續(xù)做

p-control

here?Solutionslave

loop

with

10%

offset

is

acceptable

in

most

casesmaster

loop

has

integral

action積分作用,TC

adjust調(diào)整

its

output

to

ensure

thatthere

is

no

steady

state

error

in

the

controlled

variable受控變量第15頁/共47頁16Multiloop

SystemsCascade

ControlExample

1.

the

furnace

temperature

controlProblem

(d):

Choose

the

proper

integral

time

constant

amongthe

given

values

of

0.05,

0.5,

and

5

s,

such

thatguaranteeing保證

the

system

stable,

allowing

a

slightly稍微的

underdampedresponsemaking

system

response

as

fast

as17possible第16頁/共47頁Multiloop

SystemsCascade

ControlExample

1.

the

furnace

temperature

controlSolution

of解決

problem

(d):with

PI

master

controller,

the

entire

closed-loop

system

is第17頁/共47頁18Multiloop

SystemsCascade

ControlExample

1.

the

furnace

temperature

controlProblem

(e):

determine

Kc

of

PI

controller

that

guaranteessystem

stable

when

I=0.5

without

cascadeSolution:system

is

a

single-loop

system

when

no

cascadecharacteristic

equation

of

its

closed-loop

equation

isSystem

is

stable

if

and

only

if

Kc<7.5第18頁/共47頁19Multiloop

SystemsCascade

ControlExample

1

(cont.)

the

furnace

temperature

contrSolution

of

problem

(e):compared

with與……相比較

cascadecontrolcascade

control

is

always

stable

when

I

=0.5,

from

(d)the

system

is

stable

by

Routh-Hurwitz勞氏判據(jù)analysi

s第19頁/共47頁20Multiloop

SystemsCascade

ControlSummary

of總結(jié)

cascade

control

based

on基于example

121the

system

becomes

more

stable,

andallowing

to

use

a

larger

Kc

in

master

controllermuch

faster

response

of

the

actuator

in

the

inner

loopSingle

loop

controlCascadecontrol第20頁/共47頁Multiloop

SystemsImproving

the

DR

PerformanceFeedforward

Control■Control

of

afurnace

temperature

againDR:

Disturbance

Rejection第21頁/共47頁22Multiloop

SystemsFsImproving

the

DR

PerformanceMotivation

of

feedforward(FF)control前饋控制的動(dòng)機(jī)Temperature

T

can

also

be

effected

bythe

cold

process

stream

flow

rate

FsOur

ideas

are

Measure

the

disturbancein

Fs

測(cè)量Fs中的干擾Adjust

the

valve

before the

change

of

Fs

has

no chance

to

affect

TReminder:thestreamtemperaturearepresumedbeing假定為constant第22頁/共47頁23Multiloop

Systemsalance平衡Feedforward

ControlDerive導(dǎo)出process

modelusing

heat-mass

b熱質(zhì)量where?C:

the

controlled

variable,

(i.e.,

T)GL:

the

heat

transfer

function,Gp:

the

mass

transfer

functionsto

track

R

precisely,為了精確地跟蹤Rwe

ideally理想的

setR=C第23頁/共47頁24Multiloop

SystemsFeedforward

ControlDynamic

feedforward

control

modelTells

how

to

adjust

the

manipulated

variablewhen

changing

R,thus

1/Gp

called

setpoint

tracking設(shè)定追蹤when

changing

L,

thus

GL/Gp

called

the

FF

controllerIs

dynamical

because

C=GLL+GpM

is

derivedin源至于

a

time-domain

(a

transient瞬態(tài)

model)第24頁/共47頁25nthe

FF

controller

can

be

added

on

each

onee

tMultiloop

SystemsFeedforward

ControlImplementing實(shí)現(xiàn)the

FF

controller,

-TheGLe/lGepments基本原理

in

the

FF

systemGmL

is

load

measurement

functioGFF

is

the

FF

controllerfeedback

loop

is

omittedIf

there

are

two

more

load

variables,load負(fù)載，omitted省略，be

added

on被添加在26第25頁/共47頁Multiloop

SystemsFeedforward

ControlImplementing實(shí)現(xiàn)the

FF

controller,

G/GL

p

supposing

the

set

point

R

has

no

changes,thus

the

FF

loop

is

of

supposing

that

FF

controller

can

perfectlyreject很好的抑制

the

load

change,thus

C=0C=0第26頁/共47頁27Multiloop

SystemsFeedforward

ControlImplementing

the

FF

controller,

G

/GL

p

supposin

andgSubstitute代替

them

into

theFurther

implement

above以上進(jìn)一步實(shí)現(xiàn)

asiscalled

steady

state

compensator穩(wěn)態(tài)補(bǔ)償器FLD=andFLG=p

is

called

dynamic

compensator動(dòng)態(tài)補(bǔ)償器第27頁/共47頁28Multiloop

SystemsFeedforward

ControlTuning

the

FF

Controller

Parametersbest

practice最優(yōu)方法(1)FLD

=m+*(2)

FLG

=

0.1v

,FLD,mGm=KmLif

smallGFF=

KFFif

small*vwith

cascade

controla

=

0,

b

=0.5,

c

=

1.0,

d=

1.5,

e=

2.029第28頁/共47頁Multiloop

SystemsImproving

the

DR

PerformanceFeedforward-Feedback（FB）

Control順饋控制combine

FF

with

FB

Control—Feedback

trim反饋微調(diào)the

feedback

loop

in

FF-FB

system

handlesthe

measurement

errorserrors

in

the

feedforward

functionchanges

in

unmeasured

load

variablesset

point

changes第29頁/共47頁30Multiloop

SystemsFeedforward-Feedback

(FF-FB)

ControlFinding

the

closed-loop

transfer

functionmove

G*vGp

to

form

Fig.

bwrite

down

the

final

resultwhererearrange

the

equation

above31?he第30頁/共47頁Multiloop

Systems(1)

the

cascade

control?Usingaflowcontroller(FC)inaslaveloop次環(huán)tohandlethefuelgasflowdisturbanceFC

has

the

transfer

function

Gc2Slave

loopFeedforward-Feedback

(FF-FB)

ControlExample

2.Solution:Entire

transfer

function33第32頁/共47頁Multiloop

SystemsFeedforward-Feedback

(FF-FB)

ControlExample

2(cont.):Solution:(2)

The

FF

ControlFT

sends

the

signals

to

FFC

A

summer

( )

combines

signals

from

FFC

andTCits

output

becomes

the

set

point

for

FC第33頁/共47頁34Multiloop

Systems.):Feedforward-Feedback

(FF-FB)

ControlExample

2(contSolution:(3)

The

master

looptemperature

T

is

measured

by

(TT)T

is

sent

to

TCTT

acts

to

reduce

the

deviation偏差in

the

furnace

temperature第34頁/共47頁35Multiloop

SystemsImproving

the

DR

PerformanceRatio

Control比例控制FuelgasAirDR:

Disturbance

Rejecftlioown36第35頁/共47頁Multiloop

SystemsRatio

ControlConsidering

air

flow

rate

in

the

furnace

controlMotivation動(dòng)機(jī):maintaining

FFG

at

a

defined

proportion

R

relative

to

FA,Benefit:好處Ensuring

sufficient

air

flow

for

efficient

combustion有效燃燒Regulating

air

flow

for

the

reduction

of

air

pollutant污染Application

of

interests:gases,

liquids,

powders,

slurries

or

melts氣體、液體、粉劑、漿液或熔化物■第36頁/共47頁37Multiloop

SystemsRatio

ControlConsidering

air

flow

rate

in

the

furnace

controSimple

implementation實(shí)現(xiàn)measuring

the

fuel

gas

flow

rate

FFGmultiplying

the

value

by

R

in

ratio

station38FFG在比值操作器中值增大R倍3. send

the

signal

as

the

set

point

to

the

airflow

controller.Notice

?Computation計(jì)算conductsonactualvariableratherthandeviationvariable第37頁/共47頁Multiloop

SystemsspFCRatio

ControlConsidering

air

flow

rate

in

the

furnace

controFull

metering計(jì)量

implementationSending

the

signalsfrom

the

fuel

gas

FC

and

air

FTto

the

ratio

controller

(RC)RC

takes

the

desired

R

as

set

pointand

calculate

the

proper

air

rate

FA.Taking

FA.sp

as

the

set

point

for

airand

calculate

the

control

signal第38頁/共47頁39Multiloop

SystemsImproving

the

DR

PerformanceSmith

predictor

for

time

delay

compensationSmith預(yù)估的時(shí)間延遲補(bǔ)償40DR:

Disturbance

Rejection第39頁/共47頁Multiloop

SystemsTime

Delay

Compensation:

Smith

PredictorSuppose

A

feedback

system

with

time

delayTime

lag

causes

the

deficits不足:Introducing引入

extra

phaselag相位滯后,reducing

the

gain

margin增益裕度,不穩(wěn)定的一個(gè)重要來源The

characteristic

equation

2.3. a

significant

source

of

instability.Motivation動(dòng)機(jī):How

to

cancel

the

impacts

of

the

time

lag

of

a

process?41第40頁/共47頁Multiloop

SystemsTime

Delay

Compensation:

Smith

PredictorInterpretation

of闡釋the

transfer

functionassuming

that

the

process

model

is

known,Construct構(gòu)造theblockdiagram（asfollow依下列各項(xiàng)）.PredictorActualtime

delayprediction

loopExponential

terms

are

canceled

out!!第指4數(shù)1頁部/共分47被頁抵消42Multiloop

SystemsTime

Delay

Compensation:

Smith

PredictorInterpretation

of闡釋the

transfer

functionThe

time

delay

effect

is

canceled

out

due

tosystem

with

Smith

predicatorsystem

without

Smith

predicator第42頁/共47頁43Multiloop

SystemsTime

Delay

Com