cac bo dkh

7/26/2019 Cac bo dkh

1/46

09/2007

Cc thut ton iu khin tiu biu

iu khin phn hi Feedback Controliu khin ni tng Cascade Control

iu khin TlRatio Controliu khin Feedforward

PID v chnh nh PID


2/46

09/2007

iu khin phn hi (Feedback Control)

Khi nim:L khi nim iu khin da trn nguyn tc lintc o (hoc quan st) gi tr bin c iu

khin v phn hi thng tin v b iu khin tnh ton li gi tr ca bin iu khin.-> Haycnc gi liu khin vng kn.

Cu trciu khin:w:u vo qu trnhz:u ra qu trnh

y:u vo b iu khinu: Cc tn hiuiu khin

M hnh qu

trnh

Biukhin

zw

u y


3/46

09/2007


V d: iu khin qu trnh trao i nhit iu chnh lu lng hi nng (biniu khin) da trn

sai lch gia nhit du ra (binc iu khin) vgi tr t (SP)


4/46

09/2007


nh gi : u im: C kh nng n nh cao,loi b

nhiu bt nh, Bn vng vi sai lch mhnh. Nhc im: Tc ng chm, nh hng ca

nhiu, cn sdng thm cm bin..ng dng :

c ng dng rng ri trong thc t, vthng kt hp vi iu khin truyn thng b nhiu, ci thin tc


5/46

09/2007

iu khin ni tng (Cascade)

Khi nim :

L dng m rng ca cu trc iukhin vng n, gip loi b mt phnnh hng ca nhiu, ci thin tc

p ng v thng kt hp nhiuchin lc iu khin khc nhau nhiu khin phn hi,iu khin t l

.


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09/2007


Cu trc : Cu trc ni tip (cu trc truyn thng)

Cu trc song song (khng ch u vo)


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09/2007


V d :iu khin bung traoi nhit trit tiu sm nh hng ca nhiu ta s dng

mt vngiuchnh lu lng phatrong trong, sdng

thm mti lngo lu lng


8/46

09/2007


nh gi:

u im :Ci thin kh nng loi bnhiu,gim qu iu chnh,ci thin

tnhnnh v nng cao tnh bn vngca h kn Nhcim: Chi ph tn km


9/46

09/2007


ng dng : Vng iu khin phn hi n khng p ng c

yu cu cht lng. C th d dng o c v iu khin c mt

bin qu trnh th hai (c lin quan ti bin thnht)

Bin c iu khin th hai th hin r rt nhhng ca nhiu khoc

C mt quan h nhn qu gia bin iu khin vbinciu khin thhai

c tnh ng hc ca bin th hai phi nhanh hnc tnhng hc ca bin thnht


10/46

09/2007

iu khin Tl(Ratio Control)

Khi nim:iu khin tll duy tr quan hgia

hai bin nhm iu khin gin tip mtbin thba => thc cht l mt dng

iu khin truyn thng.


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09/2007


Cu trc:


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09/2007


V d: iu khin qu trnh trao i nhit


13/46

09/2007


nh gi : u im: gip n gin ha cc bi ton phi

tuyn Nhc im: tnh phi tuyn ca m hnh(1), gi

tr t thng thay i lin tc khng bittrc(2)

ng dng: Gii quyt cc bi ton phi tuyn, thay v phi

tuyn tnh ha xp x m hnh hoc s dng cc

b diu khin phi tuyn phc tp. Thit k cu trc n bin cho qu trnh a bin

c n gin, gim thiu tng tc cho giacc vngiu khin.


14/46

09/2007

iu khin Feed-forward

Khi nim:L qu trnh iu khin trong s bin nhiu qu trnhco va ti b iu khin hoc tn hiu gia cc qutrnh tcng trc tip qua li ln nhau. Da vo gi tr oc cng vi gi tr t, b iu khin tnh ton va ragi tr cho bin iu khin. Chnh v th phng php nycho php b nhiu nu nhiu bit trc.

Cu trciu khin:

Biu khintruyn thng

Qu trnhBin iu

khinBin cn

iu khin

Bin cho(gi trt)

Nhiuqu trnh

Tn hiu tqutrnh tng tc


15/46

09/2007

iu khin Feed-forward

V d: iu khin p sut chn khngbung t hay p sut bao hi:

PT

K

TA A

K

FTFT

Yu cu nhin liu

(b)(a)

(d)

(c)im t

Tng lu lnghi ca cc l

p sut hi Lu lng hi l 1 Lu lng hi l 2


16/46

09/2007

iu khin Feedforward

nh gi : uim:

Bc cc nhiuc tnh ton

png nhanh hn v chnh xc hn Thch hp iu khin tc ng qua li ln nhau, iuchnhi tng cn gi mt gi tr nnh.

Nhc im: tnh phi tuyn ca m hnh(1), tnh tonhm feedforward kh phc tp.

ng dng: Gii quyt cc bi ton phi tuyn, thay v phi tuyn tnh

ha xp x m hnh hoc s dng cc b diu khin phituyn phc tp.

Thit k cu trc n bin cho qu trnh a bin c ngin, gii quyt vn tng tc cho gia cc vng iukhin.

Thng ng dng nhiu vo iu khin gi n nh lu

lng, nhit, p sut cho qu trnh.


17/46

09/2007

iu khin PID

y l thut iu khin phbin nhthin nay


18/46

09/2007

iu khin PID

Thut ton PID tnh ton lin tc tc ngiu chnh u(t) nhm mc ch t c sai

lch e(t) = 0

3 thnh phn c lp vi nhau:P (Proportional) : tl

I (Integral) : tch phn

D (Derivative) : vi phn

Biu khin thc hin di dng P, PI, PD, PID


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09/2007

NH HNG CC THNH PHN PID

Biu khin tl(P): Hm truyn: RP(s)=Kp

Tc ng tn hiu t v nhiu: i tng khu qun tnh c tr:

Tc ng ca tn hiu t

Tc ng ca nhiu

1+

= Ts

se.kdtW

k.K

k.K)s(Wlim)t(hlim

p

p

xyst +

==

10

k.K

k)s(Wlim)t(hlim

p

fyst +

== 10


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09/2007

CC BIU KHIN PHN HI PID

Biu khin tl(P): Tc ng tn hiu t v nhiu:

Xt i tng l khu qun tnh tch phn c tr

Tc ng ca tn hiu t

Tc ng ca nhiu

10

=== k.K

k.K)s(Wlim)t(hlim

p

p

xyst

pp

fyst Kk.K

k)s(Wlim)t(hlim 1

0===

)Ts(s

e.kW

s

dt 1+=


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09/2007

Thnh phn P

Sai lch tnh

phthuc SP

u = Kc.eC sai lch tnh (offset)

Kc ln:

_____Kc nh

_____


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09/2007


Biu khin tl(P):

nh gi: u im : n gin, tc ng nhanh

Hthng c tnh n nh cao Nhc im:

C sai lch tnh chxc lp-> Tng Kp gim

sai lch tnh->>Ph hp nht vi cc i tng qun tnh-tch phn.


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09/2007


Biu khin tch phn (I): Hm truyn: RI(s)=1/sTi Tc ng tn hiu t v nhiu:

i tng khu qun tnh tch phn c tr:

Tc ng ca tn hiu t

Tc ng ca nhiu

)Ts(s

se.kdtW 1+

=

10

=== k.K

k.K)s(Wlim)t(hlim

i

i

xyst

00

0===

k.K

)s(Wlim)t(hlim

i

fyst


24/46

09/2007


Biu khin tch phn (I):

nh gi: u im : Kh c sai lch tnh

*Nhc im: p ng chm do U(t) chm pha so vi e(t) Tnh n nh ca hthng thp(dmt n nh)

->>Ph hp nht vi cc i tng qun tnh,thng dng vi thnh phn tlP to

thnh bPI


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09/2007


Biu khin vi phn (D): Hm truyn: RP(s)=Kds (l tng)

(Thc t)

Tc ng tn hiu t v nhiu:

i tng khu qun tnh c tr:

Tc ng ca tn hiu t

Tc ng ca nhiu

1+

= Ts se.kdtW

01

0

0

===

)s(Wlim)t(hlimxy

st

kk

)s(Wlim)t(hlimfy

st===

10

1+=

sTsK)s(R

d

dD


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09/2007


Biu khin tl(D): Tc ng tn hiu t v nhiu:

Xt i tng l khu qun tnh tch phn c tr

Tc ng ca tn hiu t

Tc ng ca nhiu

k.K

k.K)s(Wlim)t(hlim

d

d

xyst +

== 10

=== 00

k)s(Wlim)t(hlim

fyst

)Ts(s

e.kW

s

dt 1+=


27/46

09/2007


Biu khin tl(D):

nh gi: u im :

U(t) sm pha so vi e(t)-> Tcng nhanh

*Nhc im: Khuych i nhiu lon Cht lng iu chnh km, dgy mt n nh Khng thsdng n c


28/46

09/2007

iu khin PI

Phng trnh

I: thi gian tch phn (giy, pht)

I cng nh, ng gp ca thnh phn tch phntrong tng tc ng cng ln


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09/2007

iu khin PI


30/46

09/2007

iu khin PI


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09/2007

iu khin PI


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09/2007

iu khin PI

Tc ng ca tng thnh phn P, I

0 20 40 60 80 100 120 140 160 180 200-2

0

2

4

6

8

10

12

P-action steps

controller initially

I-action continues to increase

controller output

process response

controller output


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09/2007

iu khin PI

u im: Loi trc sai lch tnh

Nhc im Tng tc gia 2 tham siu chnh

Thnh phn I gy ra dao ng, gim n nh

y l loi biu chnh c dng rng rinht trong hPID


34/46

09/2007

iu khin PI

Tng tc gia 2 thnh phn P v I

Trng hpcbn


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09/2007

CC PHNG PHP CHNH NH PID

Phng php Ziegler nichols 1(Phng php c tnh p ng bc

thang )ng dng :

Cc i tng c c tnh qun tnh hocc tnh qun tnh tch phn vi thi giantrtng i nh.

p dng i vi hh, c thtch ri ccbiu khin khi hthng


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09/2007


Phng php Ziegler nichols 1 Cch tin hnh : Cho tc ng tn hiu vo la xung step Xc nh tn hiu ra c dng gn vi khu

qun tnh bc 1 c tr

Xc nh cc tham sT v bng cch ktip tuyn ti im un Tnh ton cc tham sca bPID theo

bng

.( )1

s

DT

K eW s

Ts

=+


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09/2007


Phng php Ziegler nichols 1

Lut K Ti

Td

P T/k

PI 0.9T/k 0.33

PID 1.2T/k 2 0.5


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09/2007


Phng php Ziegler nichols 1(Phng php c tnh p ng bc thang )

ng dng :

p dng cho mt di rng qu trnh cngnghip, kcmt squ trnh khng nnh.

p dng cho hkn khng thtch ri biu khin ra khi h thng.


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09/2007


Phng php Ziegler nichols 2 Cch tin hnh : Thit lp khng cho cc thnh phn ID tc

ng (Td=0, Ti=)

Thay i thnh phn Kp sao cho hthngtrn bin gii n nh Xc nh cc tham sTth v Kmax bng thc

nghim Tnh ton cc tham sca bPID theo

bng


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09/2007


Phng php Ziegler nichols 1

Lut K Ti

Td

P 0.50Kmax

PI 0.45Kmax 0.85Tth

PID 0.60Kmax 0.5Tth 0.125Tth


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09/2007

CC NH HNG CHNH NH PID

Chtiu cht lng Thay i tham s

Tng Kc Gim Ti Tng Td

Thi gian p ng Gim Gim t Gim tThi gian qu Thay i t Gim Thay i tqu iu chnh Tng Tng Gim t

Hstt dn Thay i t Tng GimSai lch tnh Gim Trit tiu Thay i tTn hiu iu khin Tng Tng Tng

dtrn nh Gim Gim TngBn vng vi nhiuo

Gim Thay i t Gim


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09/2007

NG DNG PID TRONG MT SVNG IU KHIN

iu khin lu lngQu trnh v cc cm bin lu lng u p ng

nhanh, c tnh ng hc ca vng kn c quytnh bi c tnh ca van iu khin(ccu chphnh)

->Thng sdng biu khin PI

FT

FC FlowSetpoint


43/46

09/2007


iu khin mcc tnh ng hc ca cm bin v c cu chp hnh

nhanh hn s o vi qu trnh, qu trnh c tnh tch phn (I)->S dng b iu khin P (hoc PI nu c yu cu cao v chnh xc)

Fin

FC

LT

RSP

FT

Fout

Lsp

LC


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09/2007


iu khin p sut khc tnh ng hc ca qu trnh v cm bin nhanh hn sovi c cu chp hnh, qu trnh c tnh tch phn , yu cucao v chnh xc v tnh an ton

->Sdng b iu khin PI (hng sthi gian tch phn nh).

PT

PC

Vent

Psp

C.W.


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09/2007


iu khin nhit c tnh ng hc ca qu trnh v cm bin chm

hn so v

i c

c

u ch

p hnh, qu trnh c dao

ng,bin i chm, t chu nh hng ca nhiu qu trnh

->Sdng biu khin PI (hoc PID nu i hi png nhanh)

RSP

TT

FC

Gas

FT

TC Tsp

Process

Stream


46/46


iu khin thnh phnTng tvi iu khin nhit , Qu trnh bin i

chm hn so vi cm bin v ccu chp hnh->Sdng biu khin PI hoc PID hoc c thccthut ton cao cp.

cac bo dkh

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