Post on 11-Oct-2015
Chng 6: Chnh nh b iu khin PID
iu khin qu trnh
2Chng 6: Chnh nh b iu khin PID 2006 - HMS
Ni dung chng 6
6.1 Nhng vn c bn6.2 Cc phng php da trn c tnh6.3 Cc phng php da trn m hnh mu6.4 B tr s dng b d bo Smith
3Chng 6: Chnh nh b iu khin PID 2006 - HMS
Mc ch bi ging
Nm c nhng vn c bn v chnh nh cc tham s P/PI/PID
Nm c nhng phng php chnh nh tham s b iu khin PID thng dng nht trong iu khin qutrnh
C kh nng la chn v p dng phng php phhp vi mt qu trnh thc t
4Chng 6: Chnh nh b iu khin PID 2006 - HMS
1. Nhng vn c bn
Cc phng php tip cn (tng quan phng php chnh nh)
Vn m hnh i tng s dng Vn la chn kiu b iu khin c tnh cc vng iu khin s dng b iu khin
P/PI/PID ngha ca vic thay i, hiu chnh cc tham s
5Chng 6: Chnh nh b iu khin PID 2006 - HMS
Cc phng php tip cn
Da trn c tnh ca qu trnh (c tnh thi gian hoc tn s): ZieglerNichols (I v II), phn hi r-le (strm v Hgglund),
Da trn m hnh qu trnh: Tng hp theo m hnh mu (h kn hoc h h): tng hp trc
tip (Chen v Seborg), chnh nh lam-da (Dahlin), IMC (Morari v Zafiriou), xp x c tnh tn,
Nn c tnh tn s (h kn hoc h h): ti u m-un (Kessler), d tr bin-pha (strm v Hgglund,...),...
Ti u ha tham s (theo cc ch tiu IAE, ISE, H,...) Da trn kinh nghim: Chnh nh m, h chuyn gia
6Chng 6: Chnh nh b iu khin PID 2006 - HMS
Cc m hnh qu trnh thng dng
Bc nht:
Bc hai:
1( ) 1skeG s s
=+
5 2( ) 2 1
skeG ss s
=+ +
'5
1 2( ) ( 1)( 1)
skeG s s s
=+ +
2( )skeG s s
=
4( ) ( 1)skeG s s s
=+
6 2( 1)( )
2 1
sak s eG s
s s
+=+ +
'6
1 2
( 1)( ) ( 1)( 1)s
ak s eG s s s
+=
+ +
7 2( 1)( )
2 1
sak s eG s
s s
+=+ +
'7
1 2
( 1)( ) ( 1)( 1)s
ak s eG s s s
+=
+ +
3( ) 1skeG s s
=
81 2
( ) ( 1)( 1)skeG s s s
= + 9 1 2( ) ( 1)( 1)skeG s s s
=
7Chng 6: Chnh nh b iu khin PID 2006 - HMS
Qu trnh c ng hc bc cao?
Ba cch tip cn:1. Nhn dng xp x v m hnh bc thp2. Nhn dng v m hnh bc cao, sau xp x v m
hnh bc thp (xp x gim bc)3. Thit k b iu khin bc cao, sau xp x v cu
trc P/PI/PID
8Chng 6: Chnh nh b iu khin PID 2006 - HMS
Xp x theo phng php Skogestad -Lut chia i (half-rule)
Khi ct b cc thnh phn qun tnh bc cao ca i tng, cc hng s thi gian qun tnh b ct b c cng vo hng s thi gian tr.
Ring hng s thi gian b ct b ln nht c chia i mt na cng vo hng s thi gian tr, mt na cng vo hng s thi gian qun tnh c gi li nhnht.
i vi thnh phn p ng ngc b ct b, hng sthi gian p ng ngc cng c cng vo hng sthi gian tr.
9Chng 6: Chnh nh b iu khin PID 2006 - HMS
Cng thc xp x
( )( )
( )01
1
1
1
m
in
pjj
zis
k sG s e
s
=
=
+
=+
p1 > p2 > p3
( )1skeG s s
=+
21 2
pp
= +
20
3 12n m
ppj zi
j i
= =
= + + +
( )( )( )1 21 1
skeG s s s
=+ +
31 1 2 2, 2
pp p
= = +
30
4 12n m
ppj zi
j i
= =
= + + +
10Chng 6: Chnh nh b iu khin PID 2006 - HMS
Cn c chn kiu b iu khin?
c im ca qu trnh v thit b ng hc ca qu trnh ng hc ca thit b o c im ca nhiu o ...
Mc ch, yu cu ca bi ton iu khin Vai tr, c im ca tng lut iu khin
Vai tr n nh h thng? Vai tr trit tiu sai lch tnh? Vai tr ci thin c tnh ng hc? Tnh nhy cm vi nhiu o? ...
11Chng 6: Chnh nh b iu khin PID 2006 - HMS
c tnh vng iu khin PI(khi tng kc)
12Chng 6: Chnh nh b iu khin PID 2006 - HMS
c tnh vng iu khin PI(khi tng i)
13Chng 6: Chnh nh b iu khin PID 2006 - HMS
c tnh vng iu khin PID(so snh vi PI)
14Chng 6: Chnh nh b iu khin PID 2006 - HMS
nh hng ca thay i tham s PID
15Chng 6: Chnh nh b iu khin PID 2006 - HMS
Chn lut iu khin cho cc bi ton tiu biu Vng iu khin lu lng: ng hc ca i tng ph
thuc ch yu vo van iu khin, nhiu o cao tn => hu nh ch cn s dng lut PI.
Vng iu khin mc: Qu trnh c c tnh tch phn, php o mc thng rt b nh hng ca nhiu => lut P cho iu khin lng v lut PI cho iu khin cht.
Vng iu khin p sut cht kh: ng hc ca i tng ph thuc ch yu vo thit b chp hnh, qu trnh cng c c tnh tch phn tng t nh bi ton iu khin mc nhng cao hn v chnh xc => Lut PI l ch yu.
Vng iu khin nhit : ng hc chm, php o t chu nh hng ca nhiu cao tn => s dng lut PID.
Vng iu khin thnh phn: Tng t nh vng iu khin nhit => thng s dng PID.
16Chng 6: Chnh nh b iu khin PID 2006 - HMS
2. Cc phng php da trn c tnh
Ziegler-Nichols 1 (ZN-1): Da trn th p ng qu , cho h s tt dn 1/4, qu iu chnh 25%
Ziegler-Nichols 2 (ZN-2): Da trn c tnh dao ng ti hn (c tnh tn s), cho cht lng tng ng ZN-1
strm-Hgglund (AH) Phn hi r-le: Ci tin cch nhn dng c tnh dao ng ti hn ca ZN-2 (chp nhn km chnh xc hn)
Tyreus-Luyben (TL): Ci tin ZN-2, gim h s khuch i, tng thi gian vi phn v thi gian tch phn => b tham s thn trng hn
17Chng 6: Chnh nh b iu khin PID 2006 - HMS
Ziegler-Nichols 1
18Chng 6: Chnh nh b iu khin PID 2006 - HMS
Ziegler-Nichols 21. t h thng ch iu khin bng tay v a dn h
thng ti im lm vic, ch h thng n nh ti im lm vic
2. Chuyn h thng sang ch iu khin t ng vi b iu khin P. t h s khuch i kc tng i b.
3. Tng dn kc cho ti trng thi dao ng iu ha => h skhuch i ti hn (ku) v chu k dao ng ti hn (Tu).
19Chng 6: Chnh nh b iu khin PID 2006 - HMS
strm-Hgglund (phn hi r-le)
4 /uk d a=
20Chng 6: Chnh nh b iu khin PID 2006 - HMS
Tyreus-Luyben
21Chng 6: Chnh nh b iu khin PID 2006 - HMS
V d iu khin thit b trao i nhit1.210.75( ) (30 1)(5 1)(2 1)
seG s s s s
=+ + +
Xp x v m hnh FOPDT theo lut chia i:5.710.75( ) 32.5 1
seG s s
=+
22Chng 6: Chnh nh b iu khin PID 2006 - HMS
PI
PID
23Chng 6: Chnh nh b iu khin PID 2006 - HMS
c ti liu (sch v ti liu in t) v cc phng php: Phng php Haalman Phng php Dahlin (chnh nh lamda) Phng php DS (Direct Synthesis) Phng php DS-d (Direct Synthesis with disturbance
rejection preference) Phng php IMC (Internal Model Control) Phng php xp x c tnh tn s (xem thm tp ch
K thut iu khin, 6/2006 v K yu Hi ngh KH 50 nm thnh lp trng HBKHN, phn ban in)
3. Cc phng php m hnh mu
24Chng 6: Chnh nh b iu khin PID 2006 - HMS
3. Cc phng php m hnh mu
( )( ) ( )L sK s G s =
( ) ( )( ) 1 ( ) ( )K s G sT s K s G s= +
Cho m hnh mu (m hnh mong mun) ca h h/h kn:
( ) ( ) ( )L s K s G s=
( )( ) ( )(1 ( ))T sK s G s T s =
( )( ) ( )L sK s G s
( )( ) ( )(1 ( ))T sK s G s T s
hoc:
25Chng 6: Chnh nh b iu khin PID 2006 - HMS
Cc vn cn gii quyt Hm truyn t nhn c khng c cu trc PI/PID: Xp
x b iu khin hoc chn m hnh mu v m hnh i tng ph hp
H kn c th khng n nh ni: Chn m hnh mu thch hp, m hnh i tng thng thng khng c im cc hoc im khng nm bn phi trc o
H d nhy cm vi sai lch m hnh: Chn m hnh mu theo hng thn trng
Tm li: Hai vn then cht l chn m hnh mu phhp v phng php xp x m hnh!
Cc dng m hnh mu thng c la chn:
1( ) so
L s es
= ( ) 1
s
c
eT s s
=+ 2
( )2 1
s
c c
eT ss s
=+ +
26Chng 6: Chnh nh b iu khin PID 2006 - HMS
V d iu khin thit b trao i nhit1.210.75( ) (30 1)(5 1)(2 1)
seG s s s s
=+ + +
Xp x v m hnh SOPDT theo lut chia i:
2.210.75( ) (30 1)(6 1)seG s s s
=
+ +
27Chng 6: Chnh nh b iu khin PID 2006 - HMS
Kt qu m phng vi lut PID
28Chng 6: Chnh nh b iu khin PID 2006 - HMS
Ci thin cht lng bng b lc gi tr t(cho trng hp s dng DS-d)
29Chng 6: Chnh nh b iu khin PID 2006 - HMS
4. B tr vi b d bo Smith
M hnh l tng ca i tng:
Vn : u ra o c b chm tr, nh hng ln ti cht lng iu khin
tng khc phc: D bo u ra khng c tr da trn m hnh
0( ) ( ) sG s G s e =
0( ) ( ) sG s G s e =
30Chng 6: Chnh nh b iu khin PID 2006 - HMS
4. B tr vi b d bo Smith
0 0 0
0 0 0
0 0 0
0
( )( )
s
s
y y y y ey y y ey y yy
= + + + =
Gi s u ra thc khng c tr l y0:
31Chng 6: Chnh nh b iu khin PID 2006 - HMS
V d m phng
Chnh nh b PID theo phng php xp x p ng tn s
10
3( ) ( 1)
seG ss
=
+
32Chng 6: Chnh nh b iu khin PID 2006 - HMS
Nhim v luyn tp nh
S dng SIMULINK v m phng, th nghim cc phng php da trn c tnh
c ti liu v cc phng php da trn m hnh mu, th nghim m phng trn MATLAB
c ti liu i km v s dng 3 chng trnh phn mm nhn c tm hiu luyn tp cc phng php chnh nh khc
Chng 6: Chnh nh b iu khin PIDNi dung chng 6Mc ch bi ging1. Nhng vn c bnCc phng php tip cnCc m hnh qu trnh thng dngQu trnh c ng hc bc cao?Xp x theo phng php Skogestad -Lut chia i (half-rule)Cng thc xp xCn c chn kiu b iu khin?c tnh vng iu khin PI(khi tng kc)c tnh vng iu khin PI(khi tng ti)c tnh vng iu khin PID(so snh vi PI)nh hng ca thay i tham s PIDChn lut iu khin cho cc bi ton tiu biu2. Cc phng php da trn c tnhZiegler-Nichols 1Ziegler-Nichols 2strm-Hgglund (phn hi r-le)Tyreus-LuybenV d iu khin thit b trao i nhit3. Cc phng php m hnh muCc vn cn gii quytV d iu khin thit b trao i nhitKt qu m phng vi lut PIDCi thin cht lng bng b lc gi tr t(cho trng hp s dng DS-d)4. B tr vi b d bo Smith4. B tr vi b d bo SmithV d m phngNhim v luyn tp nh