TRNG I HC BCH KHOA H NI KHOA IN - B MN H THNG IN

*****

HNG DN S DNG

CHNG TRNH TNH TON PHN TCH

CH XC LP CA H THNG IN

CONUS

H NI - 2010

customerStamp

LI GII THIU

Chng trnh CONUS c cc gio vin b mn H thng in, trng

HBK H Ni xy dng ln u tin theo ngn ng FORTRAN IV chy trn my

tnh c nhn (th h XT) t nm 1990. M hnh HT c thit lp trong chng

trnh tng thch tnh ton cho s phc tp bt k, c xt n cc yu t gii

hn vn hnh my pht v tc ng iu chnh iu khin*). Chng trnh c

pht trin nhiu (vi ngn ng BASIC, PASCAL) vo nhng nm 1991-1992,

phc v kp thi cho vic tnh ton thit k ng dy siu cao p (DSCA) 500

KV Bc - Trung - Nam. Cc chc nng m phng DSCA, tnh gii hn truyn

ti cng sut theo iu kin n nh tnh l th mnh ca chng trnh. Sau nm

2004 chng trnh c thay i c bn, tch hp nhiu tnh nng mi v chy

trong mi trng Windows, c bit cc chc nng phn tch n nh v hiu qu

thit b FACTS. Chng trnh rt thch hp s dng cho cc NCS, hc vin cao

hc khi thc hin ti.

Ngoi phn "Hng dn chy chng trnh", ti liu cn bao gm phn

"Hng dn ng dng chng trnh" nhm gip ngi s dng khai thc hiu qu

cc chc nng ca chng trnh phc v cc mc ch nghin cu khc nhau.

Chng trnh vn thng xuyn c cp nht, sa cha. Cc tc gi lun

mong mun nhn c nhng gp , xut nhm hon thin v pht trin

chng trnh.

GS TS L Vn t

--------------------------------------- *) Cu trc chng trnh v m hnh ton c thit lp phng theo mt chng

trnh cng tn do GS TSKH . . (Nga) xut, chy trn my tnh

vn nng EC-BM 1020. Mc d c nhng thay i c bn theo thi gian, chng

trnh vn gi tn Conus ghi nh ngun gc ca chng trnh.

MC LC

Trang

Phn mt. HNG DN CHY CHNG TRNH...............................1 1.1 SON THO S LIU..................................................................................1

1.1.1 Son tho s liu mi (File>New)..........................................................1

1. Bng "S liu nt"..................................................................................1

2. Bng "Nt MBA /c di ti"................................................................2

3. Bng "ng dy".................................................................................2

4. Bng "DSCA".....................................................................................3

5. Bng "Nhnh MBA"..............................................................................4

6. Bng "Thng s MBA".........................................................................5

7. Bng "Nhnh chun".............................................................................5

8. Bng "c tnh ph ti"........................................................................6

9. Bng "Kch bn bin thin ch ".......................................................7

10. Bng "SVC, Khng, T b"................................................................9

11. Bng "Cc la chn".........................................................................10

12. Cc bng "Thng s my pht v TT", "Kch t v TK"............12

13. Bng "Thng s b"..........................................................................12.

1.1.2 Lm vic vi file c (File>Open).........................................................12

1.2 LM VIC VI S ..............................................................................13

1.2.1 Tn file s ........................................................................................13

1.2.2 Son tho s ....................................................................................14

1- nh v v tr in kt qu.......................................................................15

2- Gn thuc tnh (Update Link).............................................................16

1.3 CC CHC NNG CHY CHNG TRNH (RUN) ...........................18

1.3.1 Tnh ch xc lp (Run > Calculate steady-state).............................18

1.3.2 Tnh ton n nh tnh (Estimate Stability).........................................19

1. Kho st n nh, tnh h s d tr n nh h thng..........................19

2. Xy dng min n nh trong khng gian cng sut nt.................21

3. Phn tch nhy ............................................................................22

1.3.3 Tnh ton b kinh t (Compensation)..............................................23

Phn hai. HNG DN NG DNG CHNG TRNH...............24 Chng 1. TNH TON CH XC LP............................................24

1.1 M HNH LI IN TRONG CHNG TRNH CONUS...............24

1.1.1. Nhnh chun....................................................................................24

1.1.2. Li chun.......................................................................................25

1.1.3. S thay th cc phn t c bn ca li in..........................26

1.2 M HNH NGUN TRONG TNH TON CXL.................................32

1.2.1. Cu trc ngun................................................................................32

1.2.2. M hnh TT...................................................................................33

1.2.3. M hnh TK................................................................................. .33

1.2.4. M hnh my pht...........................................................................34

1.3. H PHNG TRNH CN BNG DNG NT.................................35

1.4 H PHNG TRNH CN BNG CNG SUT NT.......................38

1.5. XC NH BIN S CA H PHNG TRNH CXL....................39

1.6 H PHNG TRNH TI GIN CXL HT.......................................41

1.6.1. Biu din h phng trnh theo c tnh cng sut......................41

1.6.2. H phng trnh ti gin.................................................................42

1.7 NH HNG CA M HNH MY PHT V TK N TNH

TON CH HT....................................................................................43

1.7.1. Xt n cc tr s gii hn trong m hnh my pht....................43

1.7.2. La chn m hnh my pht v cc iu kin gii hn

khi tnh CXL..............................................................................................44

1.7.3. La chn m hnh TK v cc iu kin gii hn khi tnh

ton n nh..................................................................................................45

1.7.4. Cch cho m m hnh my pht v TK....................................45

Chng 2. TNH TON PHN TCH N NH TNH

BNG CHNG TRNH CONUS...................................46 2.1 NH GI N NH TNH HT PHC TP THEO TIU

CHUN MT N NH PHI CHU K......................................................46

2.2 XC NH CH VN HNH GII HN THEO IU KIN

N NH TNH...........................................................................................48

2.3 CC CH TIU NH GI MC N NH CA

HT PHC TP.........................................................................................53

1. H s d tr n nh h thng tnh theo kch bn in hnh............53

2. H s d tr n nh tnh theo cc kch bn quan tm.....................53

3. H s st p cc nt (tnh theo kch bn in hnh)..........................54

4. H s nhy bin ng cng sut nhnh........................................54

5. Tc bin thin in p v gc lch pha cc nt.............................54

6. Min n nh nt ti trong khng gian cng sut nt.......................54

Chng 3. TNH TON B KINH T TRONG LI

IN PHN PHI.................................................................................55 3.1. SUT GIM CHI PH TN THT T THIT B B

TRONG LPP.............................................................................................55

3.2 TNH TON DUNG LNG B KINH T TRONG

LI PHN PHI.....................................................................................56

1. Tnh ton sut gim chi ph tn tht v thi gian thu hi vn.........56

2. Tnh ton dung lng b kinh t.......................................................56

1

Phn mt

HNG DN CHY CHNG TRNH

(Program Operation Manual)

1.1 SON THO S LIU

1.1.1 Son tho s liu mi (File>New)

Nhn phm "New" trong "File", cc bng s hin ln nhp s liu. C th

ghi file khi mi son tho c mt phn s liu. Cc ln son tho tip sau dng

chc nng "Open". Tn file s liu c dng *.abc, file hnh v (s ) c dng *.vec.

1. Bng "S liu nt"

Hnh 1.1

Bng c 13 ct, mi nt tng ng vi s liu cho trn 1 hng. Ni dung cc

ct nh sau:

- TT: S hiu c tnh tnh ph ti (c gi tr t 0 n 24). S 0 c mc nh cho

c tnh cng (P, Q khng ph thuc U v f). Cc gi tr khc 0 tng ng vi s

hiu TT thit lp trong bng "c tnh ph ti". c tnh tnh ph ti c thit lp

(vi s hiu khc 0) khi cn xt n nh hng ca s thay i ph ti theo tn s

v in p.

- Nt s: S hiu nt trn s . Cc s hiu nt cn khng trng nhau v cho y

trn s . Hn ch s hiu nt vi 5 ch s tr xung.

- Um (kV): in p nh mc nt (ly theo in p nh mc ca phn li c cha

nt).

2

- Tn nt (ti a 30 k t): phn bit cc nt bng tn gi (khng c ngha tnh

ton). C th b trng ny.

- Pti (MW), Qti (MVAr): Cng sut ph ti nhn t nt. Du dng theo hng

cng sut ly ra t nt (ph ti). Nt trung gian cn cho cc cng sut ny bng 0.

- Ppht (MW), Qpht (MVAr): Cng sut ngun ti nt, du dng tng ng vi

hng cng sut bm vo nt. Nu nt khng c my pht th cc ct ny cho gi tr

0. Nt c th ng thi c ti v ngun. My b l ngun thun khng.

- Umod (kV): in p gi ca ngun. Cn cho khi nt c ngun gi in p.

- Qmin (MVAr), Qmax(MVAr): phm vi iu chnh CSPK ca ngun.

Cn phn bit cc loi nt ngun khi cho s liu v chng (xem thm phn Hng

dn s dng chng trnh). C cc loi ngun sau:

+ Ngun pht PV, gi in p trong php vi c th pht ca CSPK: cn cho Ppht v

Umod. Khi cn cho thm gi tr Qmin, Qmax (vi Qmin < Qmax). S liu ct

Qpht khi khng c ngha tnh ton.

+ Ngun pht PQ, gi CSPK pht khng i: cn cho Ppht, Qpht. Khi ny cn cho

Qmin = Qmax = Qpht. S liu ct Umod khng c ngha tnh ton.

2. Bng "Nt MBA /c di ti": Cng l bng thng tin nt, nhm b sung thng

tin cho cc nt c MBA iu chnh di ti. l cc nt gi c in p thanh

ci h p ca trm khng thay i trong phm vi iu chnh in p (vng /c U)

ca MBA. Nu s liu nt c cho c bng "S liu nt" th thng tin bng

"Nt MBA /c di ti" c u tin s dng.

3. Bng "ng dy":

Hnh 1.2

3

Bng ny nhp thng tin cc ng dy ti in, tr cc ng dy siu cao p.

+ N: th hin trng thi ng dy (ang lm vic: "-", b ct : "x' ).

+ Nt u, Nt cui, l(km), Ro(Ohm/km), Xo(Ohm/km), Bo(S/km) ln lt l: s

hiu nt u, nt cui, chiu di, in tr, in khng, dung dn ca mt km ng

dy trong cc n v tng ng.

+ Tn nt u, Tn nt cui: khng cn cho, my s t ng chuyn thng tin (khi

c) t bng "S liu nt".

+ Dng cc i: nhp gii hn dng in theo iu kin pht nng. Mc ch

tnh h s mang ti v hin th mu trn s cho nhnh ng dy. S liu ny ch

nh hng n kh nng hin th mu trn th (khi quan tm).

4. Bng "DSCA":

Hnh 1.3

Bng ny nhp s liu ca cc ng dy siu cao p (DSCA). Cc s liu

c nhp hon ton tng t nh cc ng dy thng (cao v h p), tuy nhin

s c tnh ton theo m hnh cc ng dy di vi thng s ri (xem Hng dn

ng dng chng trnh).

Hai pha ca DSCA (nt 1 v nt 2) c th c khng in b ngang (Shunt

Reactor). Nu c, c th nhp s liu trc tip trong bng ny bng cch cho cng

sut (MVAr) v in p nh mc (kV) ca mi khng. Nu khng cho s liu trong

bng ny, cc khng cn c th cho ring trong bng SVC, khng, t b.

4

5. Bng "Nhnh MBA" : nhp s liu cc nhnh MBA.

Hnh 1.4

+ MBA: la chn loi (2 cun dy, 3 cun dy-hoc t ngu).

+ N: trng thi hin hnh (lm vic: "-", b ct ra: "x").

+ Nt cao, Nt trung, Nt h: s hiu nt thanh ci cc pha ca MBA.

+ Nt gia: s hiu nt cn c nh s thm trong m hnh MBA 3 cun dy

hoc t ngu, thc cht l nh s cho im tm ca s thay th hnh sao ca cc

MBA 3 cun dy (t ngu). Ch , in p nh mc ca nt ny c ly theo pha

cao p.

+ u phn p: nhp in p iu chnh (lch khi nh mc) tnh bng % khi vn

hnh cc u phn p khc nh mc. V d MBA c cc nc iu chnh tng

ng 2,5%, ang t thp 2 nc so vi nh mc th "u phn p" cn c cho

bng % l : -5% = -2 x 2,5%.

+ S hiu MBA: l thng tin quan trng nhn thng s MBA a vo tnh ton.

Khi cho mt s nguyn vo ct ny tng ng vi vic xc nh my bin p

nhnh ang xt c thng s nh MBA cho trong bng "Thng s my bin p" vi

s hiu tng ng.

+ Tn nt cao, Tn nt trung, Tn nt h: khng cn cho, s c chuyn sang t

cc bng thng tin nt.

5

6. Bng "Thng s MBA": nhp thng s ca cc MBA c trong s .

Hnh 1.5

Mi MBA c cc thng s nm trn mt hng.

+ MBA: la chn MBA (2 cun dy, 3 cun dy-hoc t ngu).

+ S hiu MBA: cn nhp khng trng nhau. Cc s hiu ny s c chn khi thit

lp bng thng tin "Nhnh MBA" do cn gi c nh. Mi khi sa cha s hiu

MBA trong bng ny s nh hng n thng tin cc nhnh MBA.

+ Cc ct cn li: tng ng vi cc k hiu quen bit v thng s MBA.

7. Bng "Nhnh chun":

Hnh 1.6

Nhnh chun l khi nim nhnh c bn dng trong m hnh li in (xem Hng

dn ng dng chng trnh). Mi phn t u c th m t bi mt hay mt s

nhnh chun trong s thay th tnh ton v nhp s liu theo bng ny. Tuy

nhin, thun tin cho ngi s dng cc ng dy, DSCA, cc MBA c m

6

t trong cc bng ring, my s t ng tnh thng s cho cc nhnh v s thay

th. Cc phn t cn li cn tnh v nhp s liu theo nhnh chun (v d t b dc).

+ N: trng thi ca nhnh (lm vic: "-", b ct ra: "x").

+ Nt u, Nt cui: S hiu nt u nt cui ca nhnh. Khng phn bit th t

u, cui. Vi nhnh ni t, nt "t" cn ly s hiu 0.

+ R(G) v X(B): l phn thc v phn o ca tng tr (dn) ca nhnh chun. Cc

nhnh chun khng ni t cn c cho theo in tr R, in khng X vi n v

tnh l . Mi nhnh chun ni t u phi c cho bng tng dn. n v tnh

tng dn lun phi l S (10-6 1/). Tng dn cm khng ni t mang du dng,

dung dn ni t mang du m.

+ K1 v K2: l phn thc v phn o ca h s bin p phc. Vi nhnh khng bin

p c th cho K1 = 1; K2 = 0 hay cho K1=0; K2 =0 (nh nhau i vi chng

trnh).

+ Tn nt: khng cn cho, s c chuyn sang t bng "S liu nt".

8. Bng "c tnh ph ti"

H

nh 1.7

Bng ny cho php thit lp 24 dng c tnh tnh khc nhau ca ph ti nt.

Cc c tnh tnh c tim cn theo cng biu thc, ch khc nhau bi cc h s.

Biu thc chung:

7

.f

fff;U

UUU

);f.dd](U.bU.bb[Q)f,U(Q);f.cc](U.aU.aa[P)f,U(P

0

0*

0

0*

*102*2*100

*102*2*100

==+++=

+++=

Cc tr s P0, Q0 - l cng sut cho tng ng vi in p v tn s U0, f0.

Cc h s cn tha mn iu kin: a0+a1+a2=1; b0+b1+b2=1; c0+c1=1; d0+d1=1.

+ Dng c tnh: nh s hiu cho c tnh (t 1 n 24). S hiu ny s c chn

cho ct TT trong cc bng thng tin nt. S hiu 0, c mc nh cho c tnh

cng (khng thit lp trong bng), tng ng vi: a0 =1; b0=1; c0 =1; d0 =1, trong

khi cc h s cn li u bng 0.

V c0+c1=1; d0+d1=1 nn trong bng ch cn cho c1 v d1.

9. Bng "Kch bn bin thin ch "

Chng trnh c chc nng tnh lin tip nhiu ch theo nhng kch bn khc

nhau v bin thin thng s. Bng ny cho php thit lp cc kch bn theo mun.

Bng cn c s dng trong cc chc nng phn tch n nh (xem Hng dn ng

dng chng trnh).

Cc thng s bin thin c phn bit theo m (code), bao gm cc thng s ca

nt nh trong hnh 1.8. nhn bng ny cn nhp p (chut tri) trang ang

son tho (bng Kch bn bin thin ch ).

+ Nt: s hiu nt c thng s lm bin thin.

+ code: nhp m thng s. C th nhp trc tip m s theo bng hoc nhp p vo

hng trong bng m. M s t ng gn vo v tr con tr bng ngoi.

+ Xmin, Xmax: gii hn 2 pha ca phm vi lm bin thin thng s. Ch , tr s

thng s ch u cn nm gia 2 gi tr trn.

+ Delta X: bc thay i thng s, c th m (li) hoc dng (tin).

C th to cc "kch bn" vi s bin thin ca mt hay ng thi nhiu thng s

nhiu nt khc nhau. Khi c nhiu thng s bin thin ch cn nhp s liu lin tip

theo cc hng. Bc bin thin thng s (DeltaX) c th hon ton khc nhau. Gii

hn lm bin thin mi thng s cng c th ty .

8

Kt thc cc hng (tng ng vi 1 kch bn) cn cho thm mt hng ton s 0, tr

ct u tin ca hng ny (ng vi ct "nt") cho gi tr yu cu v chnh xc khi

tm gii hn n nh. Tr s ny cho di dng thp phn nh hn 1, biu th sai s

cho php gia thng s bc cui cng so vi gii hn mt n nh. Nu cho gia

tr 0 ct ny tng ng vi ly sai s mc nh l 0,25DeltaX. Nu cho 0,5 tng

ng chn sai s cho php bng na bc DeltaX.

Hnh 1.8

Ch thch v kch bn lm bin thin thng s ch :

- Khi phn tch n nh, rt hay s dng "kch bn in hnh" bin thin ch h

thng. l kch bn tng ng thi cng sut cc nt ti (gi nguyn cos) ln

cng t l (bc tng 1%) v cng sut cc t my pht (tr nt cn bng). Kch bn

ny c th to nhanh bng cch nhn phm "Typical Scenario" pha trn bng.

9

- xa mi kch bn to trn mn hnh nhn phm "Remove Scenario".

- Khi c kch bn chng trnh s tnh ton nhiu ln vi thng s thay i, nu n

gii hn mt n nh, qu trnh tnh ton s dng v in kt qu.

- Nu cha n gii hn mt n nh nhng ht gii hn ca mt thng s no th

thng s ly gi tr cui cng lm thng s tnh ton bc tip theo. Cc thng

s cn li tip tc thay i. Qu trnh ch dng li khi tt c cc thng s n gii

hn.

- Kt qu tnh ton ch c in y cc bc hoc in tm tt (chn lc) ty

thuc la chn trong bng "Ty chn".

- C th thc hin lin tip 2 hay nhiu kch bn. Khi cc kch bn c phn

bit bng cch cho thm 1 hng ton s 0 (sau bc cho sai s).

10. Bng "SVC, Khng, T b":

Hnh 1.9

Bng ny dnh ring cho thng s SVC, khng in b ngang, t b tnh.

+ Vi SVC: Nhp tn nt c thanh ci ni vi SVC. Tr s Qmin, Qmax l gii hn

iu chnh c du bt k nhng cn tha mn Qmin < Qmax . Cn nhp thm 3 s

hiu nt (Nut-F, Nt-C, Nut-X) gip cho m hnh ni b SVC (chn s bt k, ch

cn khng trng vi s hiu cc nt khc).

+ Vi khng b ngang c nh: cn nhp Qmin = Qmax = QKm (cng sut nh

mc) v U0 = Um ca khng. Khng cn nhp thm s hiu Nut-F, Nt-C, Nut-X.

10

+ Vi T b tnh: nhp Qmin = Qmax = QCm (cng sut nh mc) v U0 = Um ca

t. Khng cn nhp thm s hiu Nut-F, Nt-C, Nut-X.

11. Bng "Cc la chn":

Hnh 1.10

+ Tn s: mc nh 50 (vi li 50 hez). Gi tr ny c s dng gi tn s h

thng khi la chn tnh CXL v CQ vi tn s cho (c nh my iu tn).

Khi tnh vi tn s h thng thay i, tr s cho trong ny c s dng lm tr s

t f0 ca c tnh tnh.

+ Nt cn bng: l s hiu nt thanh ci ca h thng cng sut v cng ln hoc

ca nh my iu tn (khi tnh ch vi tn s cho). Khi tnh vi ch tn s

thay i, nt cn bng c ngha l "nt c s" (c gc pha bng 0) tnh gc pha

tng i ca cc nt. Khi c th chn nt bt k (xem Hng dn ng dng

chng trnh).

+ chnh xc yu cu: l sai s cho php, tnh theo lch (khng cn bng) cng

sut nt.

11

+ Nt xc nh CS ng b: s hiu nt cn in tr s dP/d. Khi tnh n nh c th

cn quan tm n tr s ny mt nt no . Khi khng cn in, s 0.

+ Di iu khin in theo U v theo P: gip in chn lc (trong kt qu tnh) cc nt c

lch in p hoc cng sut vt qu mt gii hn no so vi nh mc. Kt

qu ch c in cho cc nt c thng s U hoc P lch qu gi tr cho trong ny

(theo n v tng i). Nu gi tr 0, tt c cc nt u c in kt qu. Nu cho

tr s ny rt ln (kt qu cc nt u khng c in tr cc nt ngun v nt cn

bng). Khi cn in thm cho nt no th a vo bng "Nt in kt qu".

+ Cc la chn khc:

- In d liu u: c in, khng in.

- Tnh xp x u: c tnh, khng tnh, c tnh v in. "Tnh v in xp x u" thng

c la chn phn tch kt qu khi php tnh khng hi t. La chn "khng

tnh xp x u" c th rt ngn thi gian tnh, nhng c th lm gim kh nng hi

t (ni chung, khng nn la chn).

- Tnh ch vi tn s : cho hoc thay i. Ch chn "thay i" khi kho st h

thng khng gi c tn s bng iu tn (ch thiu cng sut tc dng).

- Tnh n nh vi tn s: cho hoc thay i. Ch chn "thay i" khi cn xt n

nh hng tn s trong qu trnh lm bin thin ch .

- Xc nh n nh: mc nh "c". Ch chn "khng" trong trng hp mun

nghin cu tm kim cc im cn bng khng n nh.

- Hiu chnh phng php lp: mc nh chn "bc 2". Ch chn khc i khi cn th

thay i nhm tm kim hi t.

- Kim tra thng tin vo: chn "c" pht hin sai st s liu vo. Chng trnh c

chc nng t pht hin sai st s liu vo da theo cc iu kin thc t HT:

. Nhnh ni t bt k: /g/ -105 S.

. H s bin p nhnh ni nt i vi nt j:

ijijdmi

dmjij K25,0KU

UK25,0 &&&

12

. Cng sut ph ti: Qt < Pt Open)

S dng chc nng "Open" trong "File" m file s liu c.

Cc thao tc c bn:

+ Thm mt hng: son tho tip nh ln u.

+ Xa mt hng: t con tr vo hng cn xa v nhn phm "Delete".

+ Chn 1 hng vo trc hng no : t con tr vo hng ny, nhn "Insert".

Mt s ch :

13

- Khng cc hng ton s khng cui bng. Cn xa ht trc khi ghi file hoc

tnh ton.

- S dng chc nng "save" ghi ln file c. Ghi vo file mi dng chc nng

"save as". Khi c file s liu v file hnh v u cng c ghi.

1.2 LM VIC VI S

S ch c ngha trc quan, c kh nng cp nht kt qu tnh ton sau

mi ln thnh. Hnh v (s ) c thit lp hon ton c lp vi qu trnh nhp

s liu. C th v y s hay ch mt phn cn quan tm. Nu khng v s

chng trnh vn tnh ton bnh thng v in kt qu ra di dng text.

S c nhng ngha ng dng sau:

- In kt qu ra di dng s . Bn cnh cc nt c th in ra cc s liu quan tm

nh: in p nt, gc pha, cng sut ti v ngun. Bn cnh nhnh ng dy c th

in ra cng sut chy u v cui nhnh, tn tht cng sut tc dng v phn khng,

dng in chy trn ng dy, cng sut in dung. C th xut s vi kt qu

tnh ton km theo ra giy.

- Gip ngi nghin cu phn tch ch c cch nhn trc quan, d so snh. c

bit c chc nng hin th mu cc nhnh theo h s mang ti gip nhn ra cc phn

t non ti, qu ti.

1.2.1 Tn file s

Tn file s ni chung c s dng cng tn vi file s liu, ch khc ui: .abc

cho file s liu, .vec cho file s .

- Khi mt file mi ln u c son tho, dng lnh "save as" ghi s liu vo

file vi tn t chn th ng thi file s cng t ng c ghi. Nu s cha

v th mt file hnh v trng cng tn vn c ghi.

- Khi m file, file s liu c chn m trc, tip n chn m file hnh v. File s

liu v file hnh v trong trng hp ny c th cng tn hoc khc tn. Ni chung

cn m 2 file cng tn v mc nh l tng thch. Nu c sa cha v dng lnh

"save" th mi thay i trong 2 file cng tn u c ghi li. Ch nu khng ghi

14

m thot khi chng trnh th cc file vn khng thay i (chng trnh khng

nhc). Nu file s c kt qu, lnh "save" s ghi s c kt qu ln file

c. Nn lu mt file hnh v khng c kt qu (ton s 0) c vo li khi cn thit

(vi tn khc). Mi thay i trn s t sau lc m file, k c kt qu tnh s c

xa ht bng cch nhn phm "reset".

M 2 file khc tn thng ch gp trong trng hp mun sao chp file s

(ging hoc gn ging vi file s liu) nhm to cc file theo tn mi, sau sa

cha. Trng hp ny, sau khi m xong 2 file (c tn khc nhau) cn dng lnh

"save as" ghi theo tn mi. Nu c sa cha nhng dng lnh "save" th mi thay

i vn c ghi vo 2 file c.

1.2.2 Son tho s

Nu ang "Data" (son tho s liu), chuyn sang lm vic vi s cn

nhn phm "Diagram" (v ngc li). Cc cng c v cch thc hin v s ni

chung ging nh cc phn mm khc (tng t AutoCad). C mt s ni dung khc

bit ng ch nh sau:

- C cc s chun cho My pht, MBA, Khng in, T in.

Hnh 2.1

Nhp chut vo biu tng (s ni ln bng chn), chn tn trong "name", nhn

"OK" s nhn c hnh mu. Dng chc nng thay i t l xch (scale) v di

chuyn (move) c ln hnh v v t ng v tr mong mun.

15

- c kt qu trn s cn nh v v tr TEXT in kt qu v UpdateLink thuc

tnh cho TEXT.

Hnh 2.2

C th nh sau:

1- nh v v tr in kt qu:

i vi cc nt, kt qu c th in ra bao gm: Pt, Qt, PF, QF, U, . Chng c

th c chn in cnh nt (in tt c hoc ch vi thng s). Thng s dng text l

mt dy cc s 0 nh v v tr in. V d nt 5 trn hnh 2.2 c 4 dy s 0 c to

v a vo cc v tr cnh thanh ci ( in U v ) v pha di mi tn ( in Pt v

Qt). Sau khi gn thuc tnh th mi ln chy chng trnh chng s c cp nht

bng cc kt qu. (Nu nhn phm "Reset" chng tr thnh cc s 0 ban u, kt qu

c xa ht).

Tng t, cc nhnh ng dy c th c cc loi s liu kt qu: P1, Q1, P2,

Q2, I, P, Q, QC - tng ng l cng sut tc dng, phn khng pha nt u v nt

cui ca nhnh, dng in I, tn tht cng sut tc dng, phn khng, cng sut in

16

dung do ng dy sinh ra. Chng cng c nh v vo cc v tr mong mun bn

cnh nhnh theo cch tng t nh trn.

S lng kt qu in trn s ty theo mc ch ca ngi s dng. Khng

nht thit phi nh v ht trn s .

2- Gn thuc tnh (Update Link):

chng trnh nhn bit c dy s 0 l ca s liu kt qu no, sau khi

nh v xong cn tin hnh gn thuc tnh cho tng dy s. bt u gn cc thuc

tnh cn nhp vo phm "Update Link" (s s chuyn sang ch gn thuc tnh).

Gn xong cn nhn phm "Stop" chuyn v trang thi lm vic ca s . Ch

l nu ang ch "Diagram", sau khi nhn nhn " Update Link", mn hnh Data

s hin ra, cho php bt u gn thuc tnh.

gn thuc tnh s liu nt, chn bng "s liu nt". Nhp p chut tri

vo hng tng ng vi s hiu nt nh, mn hnh s li t ng chuyn sang s

, nhng lc ny cc thng tin nt sn sng trong b nh. a con tr n text

cn Update Link, nhp chut tri, mt bng thng s v s liu nt c hin ra.

Chn loi s liu mong mun bng cch nhp chut vo v tr trong bng. Bng n

i, cng l lc kt thc qu trnh update cho text chn. C th update lin tip cho

cc text ca nt ny (cho n ht) bng cc nhp vo text v chn thuc tnh. Mi

ln nhp vo mt text, bng thuc tnh li xut hin mt ln v n i sau khi la

chn. Khi khng cn text no ca cng nt ang thc hin th chuyn sang update

nt khc. Cch chuyn: nhp n chut phi. (Ch , nu cha update ht, c th

thc hin ln sau. Cng c th update li nu ln trc lm sai).

Sau khi nhp n chut phi chuyn nt, mn hnh li chuyn sang ch

Data vi bng s liu nt. Nhp p vo hng khc (tng ng vi nt mi) v tin

hnh qu trnh update tng t nh trn.

Tip theo c th tin hnh cho cc nhnh ng dy v cc nhnh chun.

Cch lm hon ton tng t, ch khc s dng bng "ng dy" hoc "Nhnh

chun". i vi cc ng dy, cn c thuc tnh hin th mu. Cc lm: chn nt

v ng dy cng trong qu trnh update link cho cc text. Thng thuc tnh hin

17

th mu c thc hin cui cng sau khi gn ht thuc tnh cho cc text. Ch mu

ch c hin th khi c cho tr s "dng cc i" trong bng ng dy ( tnh h

s mang ti k). Mu c hin th nh sau:

k > 1,05 - ta (qu ti nhiu);

1,0 < k < 1,05 - nht (qu ti);

0,8 < k < 1,0 - vng (bnh thng);

0,5 < k < 0,8 - xanh nht (non ti);

k < 0,5 - xanh m (qu non ti).

RB XB

R0

X0

KC-H

Cao p H p

P1 Q1

P2 Q2

I

Hnh 2.3,a

P2 Q2

Cao p H p

P1 Q1

Hnh 2.3,b

P1 Q1

Cao p H p

Trung p

RC

R0

X0

KC-H

Cao p

H p

P1 Q1

P2 Q2

I

KC-T

Trung p XC

XT

XH

RT

RH

18

Vi cc my bin p, chc nng update link ch c th cho php thc hin vi mt

nhnh trong s thay th. C th vi MBA 2 cun dy, trong trng hp chung s

thay th c dng nh trn hnh 2.3,a. Tuy nhin, ch c nhnh chnh c th xut

kt qu ra s (nhnh ngang). Dng in c tnh pha cao p. Vi MBA 3

cun dy (hnh 2.3,b), cng ch c th xut cng sut v dng in nhnh cao p

sang s (tng ng vi cng sut i vo pha cun cao p trn s .

Kt thc Update Link cn nhn nm "Stop" tr li mn hnh lm vic.

Update link c th thc hin nhiu ln ( b sung sa cha).

1.3 CC CHC NNG CHY CHNG TRNH (RUN)

1.3.1 Tnh ch xc lp (Run > Calculate steady-state)

C th thc hin sau khi son tho xong s liu hoc m file s liu c, cc

thng tin c np trong b nh. Chc nng ny cho php tnh CXL vi thng

s cho hoc hng lot ch theo kch bn bin thin thng s.

Khi tnh mt ch , kt qu c th in ra di dng s hoc di dng s . Khi

tnh CXL bng chng trnh CONUS, c tnh n nh ca h thng lun lun

c kim tra (theo tiu chun mt n nh phi chu k). V th, cui bng kt qu

c thng bo: "h thng n nh tnh" hoc "h thng khng n nh tnh".

Khi c s liu kch bn trong bng "Kch bn bin thin ch " chng trnh

s thc hin tnh ton lin tip CXL theo tng bc thay i thng s v in ra kt

qu. Cch thc in ra trong trng hp ny ty thuc la chn "Ch in cc bc

lm nng v ch gii hn" bng trong bng "Cc la chn". C cc la chn sau:

- In y kt qu cc bc, khng in y ch gii hn.

- In y kt qu cc bc, in y ch gii hn.

- Khng in y kt qu cc bc, in y ch gii hn.

- Khng in y kt qu cc bc, khng in y ch gii hn.

Ty theo mc ch nghin cu, c th la chn ph hp nhm gim bt khi lng

in.

Khi tnh vi thng s bin thin, trn s khng c kt qu no c cp nht.

19

Chc nng tnh ton CXL vi kch bn bin thin ch cng c dng

tnh ton phn tch n nh bi n cho php kho st s thay i mi thng s

trong qu trnh bin thin ch (theo kch bn) cho n trc khi mt n nh.

1.3.2 Tnh ton n nh tnh (Run > Estimate Stability)

1. Kho st n nh, tnh h s d tr n nh h thng

Sau khi thit lp kch bn bin thin ch , nhp chut vo "Estimate

Stability" trong "Run" phn tch n nh. V bn cht, chc nng ny cng ch l

tnh ton lin tip cc CXL theo kch bn. Tuy nhin, gii hn bin thin thng s

(Xmin, Xmax) c cho rng tm thy gii hn n nh. Khi "tm thy" gii

hn n nh th chng trnh s dng li v thc hin mt s tnh ton b sung (h

s d tr n nh, h s st p, v ng cong sp in p ...) v in kt qu.

Cc kch bn khc nhau s c cc kt qu nh gi khc nhau. Thng thng kch

bn c quan tm nht l kch bn c h s d tr n nh b nht (xem Hng dn

ng dng chng trnh).

Hnh 2.4

Hnh 2.4 th hin mn hnh trc khi chy chc nng phn tch n nh theo kch

bn in hnh (ca VIDU1). Cn nhp chut vo "Estimate Stability". Kt qu di

dng text c hin trn mn hnh bi WordPad vi file GHOD.dat trn a (hnh

20

2.5). File GHOD.dat b thay theo tng ln tnh, v th cn ghi vo tn file mi nu

mun lu kt qu.

H

nh 2.5

21

Hnh 2.6

Ngoi file kt qu c hin th di dng text, trn mn hnh cn c khung th

(nhp tn chng trnh "Chart" trn thanh bar bn di ni ln trn) cho php

kho st cc ng cong bin thin in p, gc lch v tc bin thin ca chng

(hnh 2.6). C th xem xt ng thi 4 ng cong ca 4 nt ty chn.

2. Xy dng min n nh trong khng gian cng sut nt

S dng bng "Kch bn bin thin ch " thc hin chc nng ny. Hnh

2.7 l mn hnh s liu trong bng "Kch bn bin thin ch " xy dng min

n nh nt ti 5 ca HT n gin (Hnh 2.2). S liu c cho vo ging nh mt

kch bn lm bin thin cng sut tc dng v phn khng ca nt 5. Tuy nhin, nh

s liu trong ct cui (N1-to-N2) m cc kch bn khc nhau c thit lp. Gi tr

trong ct X0 l ta im xut pht qu trnh lm bin thin thng s: chnh l v

tr Pt, Qt CXL u (khng cn nhp vo, chng trnh t in vo theo gi tr

c). C th cho li ta im xut pht ny bng cch cho s liu vo ct X0'.

Trng hp ny vn s dng chc nng "Run > Calculate steady-state" tnh

ton. Kt qu tnh ton c t ng ghi vo file ..\StAr.rtf. Nhn phm ChartA hoc

Excel v ng cong gii hn.

Hnh 2.7

22

Kt qu xy dng min n nh nt 5 cho v d trn nhn c nh hnh 2.8 (v

bng Excel) hoc hnh 2.9 (v bng ChartA).

Hnh 2.8

Thc cht cch xy dng min n nh l tm gii hn theo cc hng khc

nhau. Mi hng xc nh c mt im gii hn. Ct N1-to-N2 cho gii hn gc

ca cc ng ch hng lm bin thin thng s. Cc gc s c tnh l:

t 10

).5,01N( + n 10

).5,02N( +

Ngha l, kch bn u tin i theo ng c gc (N1+0,5)./10 so vi phng

ngang. Sau tng dn cho n (N2+0,5)./10. Trong v d trn l t gc -2,5/10

n 6,5/10. Thay i N1 v N2 c s im cho ng cong mong mun. C

khi phi thay i c X0 thnh X0' (v d, lc X0 qu gn bin gii).

23

Hnh 2.9

3. Phn tch nhy

ang c kch bn phn tch n nh, thc hin chc nng "Run > Calculate steady-

state" to thng tin bin thin thng s h thng. Tip nhn "Sensitivity

analysis" s nhn c cc kt qu phn tch nhy bin thin cng sut nhnh v

h s st p cc nt.

1.3.3 Tnh ton b kinh t (Compensation)

L chc nng h tr tnh ton b kinh t trong LPP (hnh tia). C cc ni dung :

1- Phn tch hiu qu t b (Compensation>Effect analysis): tr gip tm kim cc

nt t b c hiu qu (c thi gian thu hi vn ngn) v so snh hiu qu t b

cc nt rong li. Kt qu in ra l sut gim chi ph tn tht v thi gian thu hi vn

u t ca dung lng b t thm vo mi nt. Hiu qu b ch c xem xt cho

24

nhng nt c la chn. Nt la chn cn c "nh du" bng cch gn tr s "-

1" vo ct TT ca bng "S liu nt".

2- Xc nh dung lng b ti u cho cc nt chn (Compensation>Economic

Capacity). Dung lng b ch c in ra khi tha mn cc iu kin sau:

+ C nh du "-1" vo cc nt d kin t b;

+ Tt c cc nt nh du u phi c thi gian thu hi vn u t nh hn tr s

mong mun cho trong bng "S liu b kinh t".

+ Nt b c hiu qu kinh t khi dung lng b ti u ln hn mt bc tng dung

lng b khi tnh ton. Bc tng dung lng b tng ng vi "Bc tng dung

lng b" cho trong bng "S liu b kinh t ".

+ Cho cc s liu trong bng "S liu b kinh t ".

25

Phn hai

HNG DN NG DNG CHNG TRNH

(Program Application Guide)

Chng 1. TNH TON CH XC LP *)

Tnh ton ch xc lp (CXL) l chc nng chnh ca chng trnh

CONUS. Chng trnh c thit lp tng thch tnh ton ch HT c s

phc tp bt k, xt n nh hng ca cc phng tin iu chnh, iu khin

(TK, TT, /c u phn p cc MBA, cc thit b FACTS ...).

1.1 M HNH LI IN TRONG CHNG TRNH CONUS

1.1.1. Nhnh chun

Khi nim nhnh chun c s dng trong m hnh li in. Mt nhnh

ni gia 2 nt i v j bt k bao gm mt tng tr Zij (hay tng dn Yij) ni tip vi

mt my bin p l tng c h s bin p phc: ijijijijij k2jK1KK =+=& .

Nhnh chun c nh chiu ty thuc vo th t ca MBA l tng v tng tr Zij

trn nhnh ij vi v tr nt i v nt j chn. Khi , chiu tnh h s bin p lun

lun c quy c thng nht, khng ph thuc chiu ca nhnh. V d, trn hnh

1.1,a tnh i'iij U/UK &&& = th vi hnh 1.1,b phi c tnh j'jij U/UK &&& = . Ngha l ly theo hng t im gia nhnh n nt pha bn kia ca MBA trong mi trng

ijK& Zij j i

ijI& iU&

jU& 'iU&

Hnh 1-1,a. Nhnh chun

'ijI&

26

hp. Cng c th c xc nh thng nht theo hng ngc li (trong chng

trnh Conus).

Tng dn nhnh c th nhn gi tr Yij = 0 (hay Zij = ). Khi , tng ng gia

nt i v nt j khng tn ti nhnh. H s bin p c tr s kij = 1 gc pha ij = 0 khi

thc t nhnh khng c my bin p.

1.1.2. Li chun

Hnh 1-2. S li chun

i jJi

Jj

k

l

JkJl

0

Kij Zij

KklZkl

ijK& Zij j i

ijI& iU&

jU& 'jU&

Hnh 1-1,b

'ijI&

27

Li chun bao gm cc nhnh chun ni vi nhau ti cc nt v cc ngun

(hnh 1.2). Gia 2 nt bt k u c nhnh chun nu k c nhnh c Yij = 0 (thc t

khng c nhnh). Mi nt u c ngun bm vo nu k c ngun c tr s dng

bng 0 (khng ngun). Ngun c in p cho trc, dng in ngun bm vo nt

ph thuc trng thi ca li, khi ngun c coi l ngun p. Nu cho trc

dng in, in p nt ngun thay i theo trng thi ca li, ngun tr thnh

ngun dng. Nt trung gian (khng c my pht cng nh ph ti) c th coi l nt

c ngun dng bng 0. Nt ph ti l nt c ngun dng vi gi tr cng sut m (v

tnh theo hng bm vo nt). Cc my pht thc t c th lm vic c 2 ch

ngun p v ngun dng. Li chun c th c cc nhnh ni t. Nt "t" c s

hiu l 0.

p dng m hnh trn, mi phn t thc ca li in cn phi c m t

bng cc nhnh chun v thit lp s li chun.

1.1.3. S thay th cc phn t c bn ca li in

1. Cc ng dy ti in

- ng dy trn khng, in p U 35 kV: S thay th hnh 1.3.

Thng s tnh ton:

ZD = RD+jXD = (r0+jx0)l

- ng dy trn khng in p cao v cc ng dy cp:

S thay th hnh (hnh 1.4), cn xt n in dung t nhin.

l (km)

r0 , x0 (/km)

i j ZD i j

Hnh 1.3

28

Thng s tnh ton cho s hnh 1.4:

ZD = RD+jXD = (r0+jx0)l ; B = b0l .

- Cc ng dy di siu cao p:

C 2 cch m hnh: bng chui cc mt xch hnh , hoc mt s hnh tng hp

vi thng s tnh theo mng 2 ca ca ng dy c thng s ri.

+ M hnh bng chui cc mt xch hnh (hnh 1.5)

Thng s tnh ton cho mi mt xch hnh : Z = (r0+jx0)l; B = b0l m bo chnh xc cn chn l 100 km.

i jl (km) i j

r0 , x0 (/km)

b0 (1/ .km)

ZD

jB/2 jB/2

Hnh 1.4

Z Z Z jB/2 jB/2 j B/2 j B/2

l l l r0 , x0 ( /Km ) b0 (1/km )

l (km)i j

Hnh 1.5

29

+ M hnh theo s hnh tng hp (hnh 1.6).

Cc thng s tnh ton cho s hnh 1.6:

Trong : Z = (r0 + jx0).l ; Y = (g0 + jb0).l .

2. Cc my bin p in lc

+ My bin p 2 cun dy:

Thng s tnh ton (trong h n v c tn):

i jl (km) i j Z

r0 , x0 ( /Km ) b0 (1/ Km ) Y/2 Y/2

Hnh 1.6

+== 6YZ1Z

ZYZYshZZYsh

YZZ

6YZ1

12Y

2/YZ)2/YZ(th

2Y

2Y

+=

Cao p H p

i j

RB XB K

X0

R0

Nt cao p

i j

Hnh 1.7

Nt h p

Nt t

30

;XZR

;SU.

%I100Z;

QUX

SU.

100%UX;

SU.PR

20

200

dm

2dm

00

Fe

2dm

0

dm

2dmN

B

2

dm

dmcuB

=

==

=

=

+ My bin p 3 cun dy:

S thay th hnh 1.8.

Thng s s MBA 3 cun dy c tnh theo cc cng thc hon ton tng

t MBA 2 cun dy (cn tnh UN% v Pcu cho tng cun dy trc).

3. Cc khng in, t in (b ngang, b dc)

Thay th bng cc nhnh c in khng v in dung tng ng.

4. M hnh ph ti

Ph ti in c hiu nh ngun cng sut m, tnh theo hng bm vo nt.

Trong trng hp chung, cng sut tc dng v phn khng ca ph ti ph thuc

in p nt v tn s h thng theo c tnh tnh (thng ch c th xc nh bng

thc nghim v tim cn theo cc hm gii tch).

Cc dng hm tim cn thng dng:

C

T

H

C

T

H

XC XT

XH

RC

RT

RH R0

X0

KC-T

KC-H

Hnh 1.8

Nt cao p

Nt trung p

Nt h p

Nt trung p

Nt h p

Nt cao p

Nt gia

31

P(U,f) = P0 (a0+a1U*+a2U*2)(0+1f*) ; Q(U,f) = Q0 (b0+b1U*+b2U*2)(0+1f*). Trong :

U* = (U-U0)/U0 ; f* = (f-f0)/f0 ;

P0, Q0 l tr s cng sut tc dng v phn khng ng vi lc U = U0 , f = f0.

a, b, , l cc h s tim cn, cn tho mn iu kin: a0 + a1 + a2 = b0 + b1 + b2 = 1 ; 0 + 1 = 0 + 1 = 1

Trng hp ring P = const; Q = const, tng ng vi a0=1, b0 =1, 0=1, 0=1, cc h s cn li bng 0.

5. TT ph ti nt c MBA iu p di ti

Cc my bin p iu p di ti c th iu chnh thng xuyn khi mang ti.

Trong phm vi iu chnh in p (pha cao): U0-U < U < U0+U in p pha h

c coi nh khng i.

P+jQ

U

Ph+jQh

P+jQ

U

U U

U0

U

P

P0

a) b)

Hnh 1.9. Nt c MBA iu p di ti (a)

s thay th nt cao p (b) v TT ph ti

Ph(U)

P(U)

32

Khi c tnh thay i ph ti (tnh pha cao p) c dng sau:

Ph(U+ U) khi U < U0- U P(U) = P0 khi U0 -U < U < U0+U Ph(U-U) khi U > U0+U Tng t cho cng sut phn khng.

Khi tnh vi nt ti pha cao p cn s dng c tnh tnh ph ti nh trn.

Chng trnh Conus xt n ph ti cc nt ny trong bng ring (xem Hng dn

chy chng trnh).

6. Thit b b c iu khin (SVC)

Trong chng trnh Conus, SVC c thay th tng ng bng mt ngun F v 2

ti thun phn khng Q1 v Q2 c cc my bin p iu p di ti (hnh 1.10,b).

Ngun c in p gi Umod = U0, gii hn pht CSPK tng ng vi Qmin, Qmax ca

SVC. Cc c tnh tnh ca ph ti Q1, Q2 nh sau:

Hnh 1-10. SVC (a), m hnh tng ng (b) v c tnh cng sut (c)

U

SVC Qmax

QminU U0

Q1=U2/XK

Q2= -U2/XC

Q

U ~

U

FQ1 Q2

U X

a) b) c)

=

0min

0C2

2 UUkhiQUUkhiX/UQ

~

H thng kch t TK

TT Tua bin

My pht

BU

BI

UFI

UF

IF PF + j QF

IfPT

a)

Eq

b)

PT PT .f

P

m

mF

PT0

Pmin

Pmax KU

KI

Ks

IF

UF

Eq

c)

Eq min

Eq max

Eq Eq0

34

1.2.2. M hnh TT

Tc ng ca TT trong CXL c m t theo c tnh iu chnh tnh n

gin ha vi h s dc: = .fP

km

mF , trong l h s iu chnh tnh ca TT.

C cc gii hn PFmin v PFmax ph thuc vo iu kin lm vic c th ca tua bin.

Quan h gia cng sut tua bin vi lch tn s quay c dng:

)1(PPP **mF0FT +

= (qui i v pha stator) (1.1)

PFmin < PT < PFmax

PF0 - l tr s t cng sut vn hnh ca my pht (iu chnh bng tay hoc theo

lnh t ngi vn hnh). Theo iu kin cn bng cng sut: PF = PT, cng ph

thuc lch tn s. Khi tnh vi tn s quay khng i th PF = PT = PF0.

Trong chng trnh Conus, m phng tc ng ca TT (khi xt n tn s h

thng thay i) cn cho cc s liu vo bng "Thng s my pht v TT" (xem

Hng dn chy chng trnh), bao gm: PFm, PFmin, PFmax, h s iu chnh tnh .

Ni chung ch cn xt n s thay i tn s khi nghin cu cc ch c bit, v

d ch sau s c, khng m bo cn bng cng sut.

1.2.3. M hnh TK

m phng tc ng ca TK, chng trnh s dng 3 dng m hnh khc

nhau: m hnh chi tit, m hnh gn ng TK tc ng mnh, m hnh gn ng

TK tc ng t l.

1) M hnh chi tit ca TK c 3 knh iu chnh theo lch: in p, dng in

o u cc my pht v tn s quay, so vi cc tr s t. Quan h iu chnh c

dng sau:

bK**sIFU0qq )1)](.KI.KU.KE[E ++++= (1.2) Eqmin < Eq < Eqmax

Trong : UF = UF - UF0; IF = IF-IF0; * = (-0)/0 , vi UF0, IF0, 0 l cc tr

s t ca in p, dng in v tn s quay ca my pht. Kb l h s ph thuc

35

loi h thng kch t, chng kh nh c th coi Kb 0. Eqmin v Eqmax l cc gii

hn s theo kh nng iu chnh kch t.

Khi tnh ton bng chng trnh Conus, xc nh TK theo m hnh trn

cn cho Eqmin, Eqmax trong bng "Thng s my pht v TT", cn cho cc h s KU,

Ki, Ks, Kb trong bng "Kch t v TK".

2) M hnh gn ng TK tc ng mnh: coi UF=const.

3) M hnh gn ng theo TK tc ng t l: E'q = const sau in khng X'd.

1.2.4. M hnh my pht

Bn thn my pht cng cn c m hnh, th hin quan h gia cng sut

tc dng v phn khng vi s Eq v in p u cc UF:

(1.3)

Trong cc phng trnh trn, s - l h s trt, cng chnh bng * ; Xq, Xd - l

cc in khng ng b ngang trc v dc trc. EQ - l s gi tng ca my pht,

ch c ngha tnh ton. Vi cc my pht in cc n (my pht nhit in), do Xd

= Xq nn EQ = Eq. Quan h gia Eq, EQ, UF v IF tng ng vi th vec t hnh

1.12. Bt phng trnh cui th hin gii hn cho php ca cng sut phn khng.

Cc gii hn ny c quan h vi dng in kch t gy pht nng cun dy roto,

nhng cn ph thuc c iu kin pht nng li thp gy ra bi tn tht t tr v

maxFFminF

F

d

q

d

qqQ

q

Fq

q

2F

F

Tq

FQF

QQQ

coss1

U)XX

1(XX

EE

;cosX

U.EX)s1(

UQ

;PsinX

U.EP

36

dng Foucault, v th cn c cho trong cc bng thng tin nt (c lp vi Eqmin

v Eqmax).

Cn ch rng, tng ng vi cc m hnh n gin ca TK cng c cc

m hnh n gin ha cho bn thn my pht. M hnh trn ch c s dng khi

TK c m t chi tit dng (1.2).

Khi TK c m t gn ng gi E'q khng i (tc ng t l), m hnh

my pht ch bao gm s E' E'q ni tip vi in khng qu X'd. Vi m hnh

ny, sc in ng E'q c quan h vi in p u cc my pht UF v cng sut

pht ca n theo cng thc:

2

F

'dF

2

F

'dF

F''

q UX.P

UX.Q

UEE

+

+= , (1.4)

Quan h ny c s dng trong tnh ton CXL u, cng nh cc ch tip sau

khi lm bin thin thng s.

Vi TK tc ng mnh, in p u cc my pht UF lun gi c khng

i. V th trong tnh ton CXL u, cng nh tnh ton cc ch vi thng s

bin thin, my pht c coi n gin nh mt nt bit in p, c cng sut

trc tip bm vo.

1.3. H PHNG TRNH CN BNG DNG NT

Gi thit s gm ton cc nhnh chun vi N+1 nt (k c nt t). Nt t

c s th t l 0.

Trc ht, xt nt i gm ton cc nhnh ni vi j nh trn hnh 2.1,a (nt i lin

k vi my bin p l tng). Ngun dng (t my pht) bm vo nt, k hiu l

iJ& . T s bin p c tnh theo hng t gia nhnh v nt i, ngha l h s bin p

'ij

ij

i

'i

ij II

UUK == &&& .

Phng trnh cn bng dng i vi nt i theo nh lut Kic-khp I:

37

=

=N

ij0j

iij JI &&

Chuyn sang tnh theo dng 'ijI& , ta c: =

=N

ij0j

i'ijij JIK &&

p dng nh lut m cho cc nhnh:

=

=N

ij0j

iij

jiij JZ

U'UK &

&&

hay =

=N

ij0j

iij

jiijij JZ

UUKK &

&&&

=

=

=N

ij0j

ij

N

ij0j ij

iji

ij

2ij JU

ZK

UZK &&&

t =

=N

ij0j ij

2ij

ii ZK

Y - tng dn ring ca nt i ;

ij

ijij Z

KY = - tng dn tng h nhnh ij ;

Ta c phng trnh cn bng dng cho nt i:

=

=+N

ij0j

ijijiii JUYUY &&&

Nu xt nt i ni vi cc nhnh theo hng nh trn hnh 2.1,b (nt i lin k vi

tng tr Zij) ta cng c: =

=N

ij0j

iij JI &&

38

=

=N

ij0j

iij

ji JZ

'UU &&&

=

=N

ij0j

iij

jiji JZ

UKU &&&&

=

=

=N

ij0j

ij

N

ij0j ij

iji

ijJU

ZK

UZ1 &&&&

Nu t :

=

=N

ij0j ij

ii Z1Y ;

ij

ijij Z

KY

&=

ta cng nhn c phng trnh cn bng dng dng tng t:

=

=+N

ij0j

ijijiii JUYUY &&&

Tuy nhin, c s khc nhau biu thc tnh tng dn ring Yii v tng dn tng h

Yij . D nhn thy trong trng hp chung, nt i ni vi nhnh theo c 2 hng, biu

thc tnh tng dn ring c dng : +=l ijk ij

ij2

ii Z1

ZKY ;

Trong biu thc ny, tng u tnh cho k nhnh c my bin p l tng ni trc

tip vi i , cn tng th 2 tng ng vi l nhnh c tng tr ni trc tip vi nt i.

T vit c dng chung h phng trnh cho ton li:

;JUY...UYUY....................................

;JUY...UYUY;JUY...UYUY

NNNN22N11N

2NN2222121

1NN1212111

&&&&

&&&&&&&&

=+++

=+++=+++

(1.4)

Phng trnh ca nt t (i=0) c b qua do chn U0 = 0.

39

1.4 H PHNG TRNH CN BNG CNG SUT NT

Nhn hai v ca (1-4) vi tr s lin hp in p ca nt tng ng. H nhn

c s c dng:

;QjPUY...UUYUUY..........................................

;QjPUUY...UYUUY

;QjPUUY...UUYUY

NN2NNNN22NN11N

222NN222222121

111NN112122111

=+++

=+++=+++

&&

&&&&

Hay vit gn hn :

=

=+N

ij1j

iiijij2iii jQPUUYUY & ; i=1, 2, ... N

Chuyn v dng s thc vi k hiu (dng i s):

iU& = U'i+jU'i

Yij = gij + jbij

Thay vo v bin i, ta c h:

=

=+++N

ijj

iijijiijjiiiijiii fUPUUUUbUUUUgUg1

2 ),()]"''"()""''([ ;

=

=++N

ijj

iijijiijjiiiijiii fUQUUUUbUUUUgUb1

2 ),()]""''()"''"([ .

i=1,2,....,N (1.5,a)

Nu t cc i lng di dng lng gic:

.)sinj(cosyyY

;)sinj(cosUUU

ijijijijijij

iiiiii

+==+==&

40

ta c th nhn c h 2n phng trnh dng sau:

=

=+N

ij1j

iiijjiijjiiiii2i )f,U(P)cos(yUUcosyU

=

=+N

ij1j

iiijjiijiiiiii2i )f,U(Q)sin(yUUsinyU (1.5,b)

i=1,2...N

Cc cng sut v phi ph thuc in p nt v tn s th hin c tnh tnh ca

ph ti v c tnh iu chnh tnh TT ca my pht.

Cc h phng trnh (1.5) m t trng thi xc lp ca li in. Chng c gii

trong chng trnh Conus theo thut ton Newton-Raphson.

1.5. XC NH BIN S CA H PHNG TRNH CXL

H (1.5) c 2N phng trnh nn cn xc nh 2N bin s cn tm. C nhiu

phng n khc nhau, nhng li gii phn nh c ch lm vic thc ca

HT cn phi xut pht t iu kin c th ca h thng. Hn na chng c nhng

hn ch nht nh khi t hp cc bin.

Hy nhn xt t h phng trnh dng lng gic 1.6,b. Gi thit chn cc bin l

N mdun v N gc pha in p cc nt (nm hon ton v tri ca h). D chng

minh c l khi h phng trnh bt nh (ngha l c v s nghim). Tht vy,

gi s tm c nghim l N modun in p U*1, U*2, ... ,U*N v N gc pha l *1, *2, ... ,*N. Khi nu cng tt c cc gi tr nghim l gc pha vi cng mt lng khng i th cc gi tr gc pha mi i = *i+ cng tho mn h. V l tu nn h phng trnh c v s nghim. Nh vy, mt iu kin gii hn l khng

c chn tt c cc gc pha lm bin. Tht ra, nu cng tt c cc gc pha vi cng

mt tr s, v mt ton hc ch tng ng vi thay i trc chun tnh gc pha cc

s v in p nn nghim khng thay i. cc gc xc nh duy nht cn cho

trc mt gc pha bng 0 (gc trng vi trc tnh ton). Nt c gc pha c chn

41

trc ny cn c ch ra trn s khi tnh ton v gi l nt c s. V nguyn

tc, nt c s c th c chn l nt bt k (nt ngun, nt ti, nt trung gian) v

n ch c ngha tnh ton.

Nh vy v l thuyt ch c th chn ti a N-1 gc pha in p nt lm n s.

n s cn thiu phi nm trong s cc thng s ch cn li thuc h phng

trnh. C 2 trng hp cn xt:

a) H thng c 1 nh my iu tn lun gi c tn s xp x nh mc. Trong

trng hp ny d thy bin cn c a vo xc nh (bin cn tm) chnh l

cng sut tc dng ca nh my iu tn. Trng thi xc lp (c tn s nh mc)

tng ng vi mt tr s no ca cng sut NM iu tn (cn tm) lm cn bng

cng sut tc dng cho ton h thng. Cng chnh v vy nt c nh my iu tn

cn c gi l nt cn bng (b tr mi thiu tha cng sut cc ngun so vi

tng ph ti v cc tn tht). Trong trng hp ny bin tn s f nm trong cc biu

thc cng sut (v phi cc phng trnh) cn cho bng gi tr tn s nh mc (50

hez) - khng th nhn lm bin s. Nh vy khc vi khi nim nt c s, nt cn

bng c ngha vt l v phi c xc nh ng l nh my iu tn. Nt c s v

nt cn bng v nguyn tc l 2 nt khc nhau. Tuy nhin trong cc chng trnh

tnh ton, ngi ta lun mc nh nu h thng c nt cn bng th cng ng

thi chn nt cn bng lm nt c s. (Kt qu nhn c gc pha in p nt thanh

ci nh my iu tn bng 0).

b) H thng c tn s khc nh mc. l cc trng hp cn tnh ton sai lch

iu chnh tn s ca NM iu tn, hoc lch tn s cc ch sau s c (nng

n) khng m bo c cn bng CSTD tn s nh mc (cc nh my iu tn

ht gii hn iu chnh). Trong trng hp ny, bin cn chn thm chnh l tn s f

(nm trong biu thc cc c tnh cng sut). Lc ny ch c khi nim nt c s v

c th chn bt k trong h thng.

Ngoi cc iu kin bt buc nh va nu cc bin cn tm (n s) cn cn c

la chn ph hp vi tnh hung vn hnh. C th nh sau:

42

+ Mi nt c 4 thng s nm trong h phng trnh (P,Q,U,) th 2 thng s cn cho trc, 2 thng s cn li l n s.

+ Chn cc bin theo loi nt v ch vn hnh h thng nh bng sau:

Loi nt Thng s cho trc

Thng s cn xc nh (n s)

Nt ti P, Q U, Nt trung gian P = 0 ; Q = 0 U, Nt ngun PV (pht CSTD theo yu cu,

gi in p thanh ci)

P, U Q,

Nt ngun PQ (pht CSTD v CSPK theo

yu cu)

P, Q U,

Nt cn bng (nh my iu tn) U, = 0 P, Q Nt b, gi in p P = 0, U Q, Nt b, pht CSPK theo yu cu P = 0, Q U,

1.6 H PHNG TRNH TI GIN CXL HT

1.6.1. Biu din h phng trnh theo c tnh cng sut

V tri h phng trnh 1.6,b l cc hm ph thuc bin trng thi h thng.

Cc hm ny cn c gi l c tnh cng sut nt. Theo 1.6,b ta c biu thc xc

nh c tnh cng sut tc dng v phn khng mi nt nh sau:

=

=

=

+=

N

ij1j

jijiijjiii2iiijii

N

ij1j

jijiijjiii2iiijii

;)cos(YUUcosUY...)...,...U(...Q

;)sin(YUUsinUY...)...,...U(...P

(1.7)

Khi nim c tnh cng sut nt c s dng nhiu trong l thuyt phn tch n

nh. Trong mc ny, s dng khi nim c tnh cng sut vit gn h phng

trnh trng thi xc lp ca HT.

43

Xt trng hp HT c NM iu tn (gi tn s khng i f=50hez). Gi thit h

thng c N+1 nt (khng k nt t) trong c m my pht, khng k NM iu

tn (nt cn bng). Nt cn bng c chn vi s hiu N+1 khng nm trong m

my pht cn li. Trong m my pht ta li phn chia ra: c s my pht kiu PV (lm

vic ch gi in p) v (m-s) my pht kiu PQ (pht CSPK c nh). Vi cc

quy c ny ta c h phng trnh CXL:

;0),...,,,...,(;0),...,,,...,(

),...,2,1(;0),...,,,...,(),...,2,1(;0),...,,,...,(

),...,2,1(;0),...,,,...,(),...,2,1(;0),...,,,...,(

),...,2,1(;0),...,,,...,(

1111

1111

11

11

11

11

11

==

++==++==

==++==

==

+++

+++

+

+

+

+

+

FNNNsN

FNNNsN

tiNNsi

FiNNsi

FiNNsi

tiNNsi

FiNNsi

QUUQPUUP

NmmiQUUQmssiQUUQ

siQUUQNmmiPUUP

miPUUP

(1.8)

Nh vy h gm 2x(N+1) phng trnh vi cc bin nh sau:

- N bin gc lch (tnh khi gc pha ca nt cn bng N+1= 0): 1,...,N;

- s bin cng sut phn khng cc nt ngun PV: Q1, ...,Qs;

- (m-s) bin m un in p cc nt ngun PQ: Us+1,...,Um;

- (N-m) bin m un in p nt ti v nt trung gian: Um+1,...,UN;

- 2 bin cng sut nt cn bng PN+1, QN+1 .

1.6.2. H phng trnh ti gin

D nhn thy rng 2 phng trnh ca nt cn bng v s phng trnh ng vi

s bin cng sut phn khng cc nt ngun PV c tnh c lp vi cc phng trnh

cn li. Tch ring cc phng trnh ny tng ng vi loi b ton b s bin l

cng sut nt ch nm trong mi phng trnh. Nh vy c th gii ring cc phng

trnh cn li (to thnh h ti gin) tm tt cc cc bin trng thi h thng (bao

gm m un in p Ui v cc gc lch pha i cc nt). Sau khi c li gii, cc

phng trnh b loi b tr thnh cc biu thc xc nh cng sut tc dng (ca nt

cn bng) v cc cng sut phn khng cha bit.

44

Ta c h ti gin (2N-s phng trnh) nh sau:

)N,...,2m,1mi(;0Q),...,,U,...,U(Q)m,...,2s,1si(;0Q),...,,U,...,U(Q

)N,...,2m,1mi(;0P),...,,U,...,U(P)m,...,2,1i(;0P),...,,U,...,U(P

tiN1N1si

FiN1N1si

tiN1N1si

FiN1N1si

++==++==++==

==

++++

(1.9)

Vi N bin gc pha v (N-s) bin m un in p.

Cc biu thc c th ca c tnh cng sut nh trong h 1.7.

Dng (1.9) rt thun tin s dng trong cc nghin cu l thuyt v n nh

cng nh tnh ton CXL. nh thc Jacobi ca (1.9) trng hon ton vi gi tr s

hng t do phng trnh c trng chuyn ng qu h thng. Chng trnh

Conus s dng c im ny nh gi n nh tnh HT theo tiu chun mt n

nh phi chu k.

1.7 NH HNG CA M HNH MY PHT V TK N TNH TON

CH HT

1.7.1. Xt n cc tr s gii hn trong m hnh my pht

Khi tnh ton CXL cc dng m hnh my pht v TK c nh hng gin

tip n kt qu tnh ton thng qua cc tr s gii hn.

1. M hnh chi tit my pht v TK

Vi m hnh ny, c th xt n y cc loi gii hn: gii hn pht CSTD

theo cng sut tua-bin (PFmax, PFmin), gii hn iu chnh kch t v pht nng cun

dy roto (Eqmax, Eqmin), gii hn pht cng sut phn khng theo iu kin pht nng

li thp (QFmax, QFmin).

Nu la chn tnh ton vi tn s thay i, cc phng trnh v bt phng

trnh (1.1) c a vo tnh ton cng vi h phng trnh cn bng cng sut li.

Tn s f c xem nh mt n s. Nu la chn tnh vi tn s cho (c nt cn

bng), h (1.1) s b b qua.

i vi TK, ty theo la chn ch lm vic ca my pht, nt thanh ci

my pht c xc nh l nt PV hay nt PQ. Vi la chn ny, chng trnh thc

45

hin tnh CXL ln u theo h phng trnh cn bng cng sut li. Sau da

vo cc h (1.2) v (1.3) kim tra cc iu kin gii hn.

- Vi ch PQ, sau khi c UF v , h (1.3) cho php tnh c EQ v Eq. Kim tra

iu kin Eqmin < Eq < Eqmax. Nu iu kin tha mn, theo (1.2) tnh Eq0. Kt thc

tnh ton. Ngc li, QF c tnh li theo (1.3) vi tr s gii hn ca Eq. Lp li

php tnh CXL.

- Vi ch PV, sau khi c QF v , h (1.3) cho php tnh c EQ v Eq.

Kim ta iu kin QFmin < QF < QF max. Nu tha mn th kim tra tip iu kin Eqmin

< Eq < Eqmax. Nu cng tha mn, Eq0 s c xc nh theo (1.2), kt thc tnh ton.

Ngc li, php tnh CXL c lp li vi cc tr s gii hn. Lc ny cch tnh

ton s ging vi ch PQ. Thc t, trng hp ny my pht ht gii hn iu

chnh, in p u cc khng gi c gi tr Umod t.

2. M hnh n gin ha my pht vi TK tc ng t l

Trng hp ny ch c gii hn cng sut phn khng c kim tra.

- Vi ch PQ, khng c iu kin cn kim tra. Tr s E'q xc nh c theo UF

v da trn c s (1.4).

- Vi ch PV, sau khi tnh ln u nhn c QF v , thc hin kim tra iu

kin: QFmin < QF < QFmax. Nu khng tha mn cn tnh li CXL vi gi tr gii

hn. My pht chuyn sang ch PQ. Tr s E'q cng c tnh theo (1.4).

3. M hnh n gin ha my pht vi TK tc ng mnh

Cng ch c mt iu kin c kim tra l gii hn cng sut phn khng

cho ch PV. Nu khng tha mn, CXL s c tnh li vi tr s gii hn ca

CSPK (QFmin hoc QFmax). Thc cht my pht chuyn sang ch PQ.

1.7.2. La chn m hnh my pht v cc iu kin gii hn khi tnh CXL

p dng cc m hnh khc nhau, trong chng trnh Conus s dng m

m hnh v m cc gii hn (cho trong cc bng "Thng s my pht v TT" v

"Kch t v TK").

C 3 loi m hnh, c m ha bng s nh sau:

0 - m hnh n gin ha TK tc ng mnh, UF = const;

46

1 - m hnh chi tit TK vi 3 knh tn hiu iu chnh.

2 - m hnh n gin ha TK tc ng t l, E'q = const;

C 4 cch cho gii hn, c m ha nh sau:

0 - ch xt gii hn theo QF;

1 - xt gii hn theo c QF v Eq;

2 - ch xt gii hn theo Eq;

3 - b qua cc gii hn.

1.7.3. La chn m hnh TK v cc iu kin gii hn khi tnh ton n nh

tnh tm ch gii hn n nh, chng trnh Conus s dng kh nng

tnh ton vi thng s bin thin. Hot ng ca TK c xem xt theo nhng

cch khc nhau khi lm bin thin thng s h thng. C 3 kiu m hnh hot ng

ca TK (xc nh theo i lng c gi), vi cc m s nh sau:

0 - TK vi cc m hnh n gin ha: gi UF =const nu khi tnh CXL

chn m hnh my pht c TK tc ng mnh, gi E'q = const nu khi tnh CXL

m hnh my pht c TK tc ng t l.

1 - TK c m hnh chi tit, gi Eq0 = const;

2 - Khng c TK, Eq = const.

C 4 cch xt n gii hn khi lm thay i thng s h thng, vi cc m s sau:

0 - b qua cc gii hn;

1 - ch xt gii hn QF;

2 - xt c 2 gii hn QF v Eq;

3 - ch xt n gii hn Eq.

1.7.4. Cch cho m m hnh my pht v TK

Ct "code1234" trong cc bng "Thng s my pht v TT" v "Kch t v

TK" dng cho 4 ch s m lin tip. ngha cc m s theo th t t tri sang

phi nh sau:

- M s th nht: m hnh my pht v TK khi tnh CXL;

- M s th 2: cch xt n cc tr s gii hn khi tnh CXL;

- M s th 3: m hnh hot ng ca TK khi tnh ton n nh;

47

- M s th 4: cch xt n cc tr s gii hn khi tnh ton n nh.

Nh vy nu ct ny trng (tng ng cho 4 s 0) s c hiu l khi tnh

CXL my pht c m hnh TK tc ng mnh, ch xt gii hn QF. Khi tnh ton

n nh - TK tc ng mnh gi UF = const, b qua cc gii hn khi lm bin thin

thng s. Cn ch l nu thng s c cho c 2 bng th tr s trong bng

"Kch t v TK" s c u tin s dng.

Chng 2. TNH TON PHN TCH N NH TNH

BNG CHNG TRNH CONUS **) 2.1 NH GI N NH TNH HT PHC TP THEO TIU CHUN MT

N NH PHI CHU K

Tiu chun mt n nh phi chu k, ch p dng ring cho HT, ln u tin

c xut bi . . (nm 1948). C s xut pht ca tiu chun ny

chnh l phng php xp x bc nht ca Lyapunov. C th m t s lc nh sau.

Gi thit sau khi thit lp h phng trnh vi phn chuyn ng qu cho HT v

tuyn tnh ha xung quanh im cn bng, nhn c phng trnh c trng

(PTT) dng:

D(p) = a0pn + a1pn-1 +...+ an-1p + an = 0 (2.1)

Da trn (2.1) cc nh thc Hurwitz c th thit lp. K hiu n nh thc nhn c

l 1, 2, ..., n. Tiu chun Hurwitz pht biu nh sau: h thng s n nh nu tt

c cc h s ca PTT v cc nh thc Hurwitz u mang du dng.

V bn cht, khi tt c cc iu kin ca tiu chun Hurwitz c tha mn

th mi nghim ca PTT s c phn thc m. Khi h thng n nh tim cn.

Khi c t nht mt nghim c phn thc dng th h thng khng n nh. Hn na

nu nghim c phn thc dng l nghim thun thc th h thng s mt n nh

dng phi chu k, cn nu phn thc dng l ca cp nghim phc th h thng s

mt n nh dng chu k (dao ng vi bin tng trng v hn).

48

Gi thit HT ang ch lm vic n nh, khi theo tiu chun Hurwitz s

phi c: am > 0, k > 0 (vi nm ,0= , nk ,1= ). T t thay i cc thng s ch v hng lm mt n nh h thng. Lc h thng chuyn qua gii hn mt n nh th

mt bt ng thc no s phi i du, tng ng vi phn thc mt nghim no

ca PTT i du t m sang dng. Hurwitz chng minh c rng s i

du u tin xy ra tng ng vi du ca nh thc cp n. Theo cu trc ca ma

trn Hurwitz ta cn c 1nnn .a = . Nh vy n i du tng ng vi an hoc n-1 i du. Ni khc i khi h thng chuyn t n nh sang mt n nh c th xy ra i du u tin h s an hoc nh thc Hurwitz n-1. V ton hc cn c

th chng minh nu mt n nh xy ra do i du an th mt n nh c dng phi

chu k, cn nu do n-1 th s c dng dao ng vi bin tng ln v hn.

Mt khc, khi nghin cu cu trc h thng phng trnh vi phn chuyn

ng qu ca HT, nhn thy, mt n nh dng chu k v mt n

nh dng phi chu k trong HT, v c bn xy ra do cc nguyn nhn khc nhau.

Nu h thng b mt n nh do cc thng s ch th qu trnh din ra c dng phi

chu k. Cn nu do cc thng s ca thit b t ng iu chnh gy ra th mt n

nh c dng chu k (khi chnh nh sai, lm pht sinh dao ng t kch). Nh vy,

nu gi thit cc b t ng iu chnh ang lm vic ng (ng vi ch ang

vn hnh) th mt n nh xy ra i vi HT lun ch dng phi chu k v ch cn

theo di iu kin an > 0 l .

S dng tiu chun mt n nh phi chu k n gin hn rt nhiu so vi cc

tiu chun chung n nh theo Lyapunov. Hn na, HT c cu trc bt k u ch

cn s dng mt ch tiu di dng bt ng thc s rt thun li xc nh ch

gii hn (tng ng vi lc bt ng thc tr thnh ng thc). Mt u im khc

ca tiu chun an >0 l c th tnh ngay c gi tr an t h phng trnh CXL.

Nhiu cng trnh chng minh, tr s an chnh bng nh thc Jacobi ca h

phng trnh CXL lc vit dng ti gin (xem chng 1).

49

2.2 XC NH CH VN HNH GII HN THEO IU KIN N

NH TNH

Chng trnh Conus thit lp chc nng tnh ton ch vi thng s bin

thin (xem Hng dn chy chng trnh) ch yu phc v mc ch tnh ton xc

nh ch vn hnh gii hn theo iu kin n nh tnh. T trng thi ban u

(ang c n nh) cho cc thng s thay i theo mt cch no (cn gi l kch

bn bin thin thng s) h thng c th tin n ch gii hn, sau HT mt

n nh. Ch gii hn ny rt c quan tm trong thit k v vn hnh. V d,

thit k mt NMT ln ni vi h thng trung tm qua ng dy di, kh nng

pht cng sut c th b hn ch bi gii hn ti cng sut ca ng dy theo iu

kin n nh tnh. Ch gii hn c th xc nh c bng cch tng dn cng

sut tc dng pht ca nh my cho n lc HT mt n nh. Ch bc trc

khi mt n nh l ch gii hn, cn kch bn lm bin thin thng s trong

trng hp ny l tng CSTD ca my pht ln tng bc.

Bng "Kch bn bin thin ch " trong chng trnh cho php to ra kch

bn ty bng cch chn ng thi nhiu thng s, theo nhng bc tng (gim)

khc nhau (xem Hng dn chy chng trnh).

Hnh 2.1 biu th qu trnh lm bin thin thng s v sai s gia ch gii hn

tnh ton tm c v gii hn thc ca thng s. Khi "bc qua" gii hn mt n

nh, tng chnh xc, thng s c li 1/2 bc. Nu ch li n nh,

chng trnh li cho tin 1/4 bc, ngc li li tip 1/4 bc... Sai s mc nh

Gii hn thc

Gii hn tnh ton X

X X

X/2

X/4

Hnh 2.1

50

c la chn l 1/4 bc cho ban u. chnh xc c th cao hn bng cch

gim bc ban u hoc cho li sai s trong bng "Lm bin thin ch ".

V du: HT trn hnh 2.2

Nh my thy in c 4 t my, cng sut nh mc 260 MW. a cng

sut ln in p cao, nh my s dng 2 my bin p 500kV, cng sut nh mc

mi my 630 MVA. Bi ton c t ra l tm gii hn pht cng sut ti a cho

NMT v tm h s d tr n nh khi nh my vn hnh ht cng sut l 1000 MW

(khng k t dng). Xt 2 trng hp my pht c TK tc ng t l v TK tc

ng mnh.

Trc ht tnh CXL vi cng sut pht 1000 MW. in p u cc my pht c

gi l 15.75 kV. m bo in p nt ti gia ng dy, MBA 500 kV c

vn hnh u phn p tng cao thm 6,25%. M hnh my pht v cc iu kin

gii hn trong trng hp ny hon ton ph hp vi code mc nh (code1234 =

0000) nn khng cn sa li. Gii hn Qmax ca my pht c th tnh theo cos nh

mc, cho vo bng thng tin nt. Kt qu tnh ton cho thy phn b cng sut v

in p l hp l, h thng c n nh tnh (hnh 2.3).

~ ~ My pht: PFm = 4 x 260 MW

UFm = 15,75 kV

X'd = 0,42 ; cos = 0,85.

My bin p:

Sm = 2 x 630 MVA

Um = 500 kV;

UN% = 14,9 ; k=500/15,75

l1 = 400 km l2 = 250 km

3 x AC400 3 x AC330 St

ng dy l1: ng dy l2:

r0 = 0,024 /km r0 = 0,029 /km

x0 = 0,298 /km x0 = 0,299 /km

b0 = 3,76.10-6 1/km b0 = 3,74.10-6 1/km

Ph ti: St=(300+j23,6) MVA; H thng: U = 500 kV

Hnh 2.2

F B HT

1 4 3 2

51

tnh ch gii hn, cn thit lp kch bn v m hnh my pht v TK.

- Vi m hnh TK tc ng t l ta chn m hnh n gin ha E'q = const sau in

khng qu X'd.

Tn s h thng c gi khng i, nn khng cn cho cc s liu TT. Nu vn

cho s liu trong bng ny th cc tr s PFmax v PFmin s c nh hng n gii hn

lm bin thin thng s PF. Ta chn code1234 = 2300. (23 - m m hnh ca CXL:

2 - E'q = const; 3 - b qua gii hn khi lm bin thin ch . 00 - m m hnh ca

ch qu tnh n nh: 0 - E'q = const; 0 - b qua gii hn khi thng s bin

Hnh 2.3. Kt qu ch u ca HT hnh 2.2

52

thin). Trong bng "Thng s my v TT" cn b sung s liu X'd = 0,0851 (tnh

t tr s tng i cho), PFm =1260MW, Cos = 0,85. Trong bng "Kch t v

TK" khng cn thm thng s no v cc thng s trong bng ny u ng vi m

hnh chi tit.

Bng "Lm bin thin ch " cn to kch bn tng dn cng sut my pht nt 1

(code = 12, DeltaX = 10, Xmin = 0, Xmax =2000). khng b gii hn tng cng

sut, cn cho PFmax = PFmin = 0 trong bng "My pht v TT" (nu c).

T kt qu tnh c h s d tr n nh:

%5,11%1001000

10001115%Kdt ==

Hnh 2.4. Kt qu tnh ton ch gii hn

53

Theo tiu chun vn hnh h s ny khng m bo (yu cu >20%).

tnh vi trng hp TK tc ng mnh ch cn thay i code m hnh trong 2

bng "Thng s my v TT" v "Kch t v TK". Trong trng hp ny c th

chn code1234=0300 nu vn khng xt n cc gii hn (c th ch nhp 300). Nu

xt n gii hn QF s tng ng code1234=0000 (khng cn nhp g). Kt qu tnh

ton nh hnh 2.5.

H s d tr n nh:

%75,32%1001000

10005.1327%Kdt ==

Hnh 2.5

54

nghin cu theo m hnh chi tit c th s dng code1234=1310 (b qua gii

hn). Lc ny cn cho y cc thng s trong bng "Kch t v TK".

2.3 CC CH TIU NH GI MC N NH CA HT PHC TP

Chng trnh Conus c chc nng tnh ton cc ch tiu nh gi mc n

nh ca HT. C cc ch tiu sau:

1 - H s d tr n nh h thng tnh theo kch bn in hnh.

Kch bn in hnh (cn gi l kch bn t nhin) c xc nh l kch bn

lm tng ng thi cng sut tc dng v phn khng ca tt c cc nt ti trong h

thng theo cng mt t l cho n khi h thng mt n nh. H s d tr n nh

tnh theo kch bn in hnh c xc nh theo cng thc:

%.100P

PPK

0

0ghhdt

=

Trong : Pgh, P0 - l tng cng sut ph ti ch gii hn v ch ban u.

H s d tr n nh tnh theo kch bn in hnh l mt trong nhng ch tiu c

trng cho mc n nh chung ca h thng.

2. H s d tr n nh tnh theo cc kch bn quan tm.

Ngoi kch bn in hnh, ty theo cu trc v c im vn hnh, mc n

nh h thng cn cn c kim tra theo nhng kch bn khc gi l kch bn quan

tm (thit lp theo mc ch ngi nghin cu). Kch bn quan tm thng lin

quan n cc tnh hung chuyn i phng thc vn hnh. V d t ma ma

chuyn sang ma kh cn gim dn cng sut cc NMT v tng dn cng sut cc

NMN. Ch gii hn c quan tm nhm theo di h s d tr n nh. Ph

thuc vo cu trc s nhiu trng hp h s d tr theo kch bn quan tm

mang ngha quyt nh.

H s d tr n nh tnh theo cc kch bn quan tm c xc nh theo

cng thc sau:

%.100P

PPK

0qt

0qtghqtqtdt

=

55

Trong : Pqt gh v Pqt 0 l thng s quan tm trong kch bn (v d cng sut truyn

ti trn ng dy ti nng) ch gii hn v ch u.

Tng cng sut my pht ca NM tm gii hn n nh v h s d tr (nh v

d trn) cng l mt trng hp ca kch bn quan tm.

3. H s st p cc nt (tnh theo kch bn in hnh).

Vi kch bn in hnh tnh c in p cc nt ch u Ui0 v ch

gii hn Uigh. H s st p nt i c tnh theo cng thc:

%.100U

UUK

0i

0ighiiU

=

Nt c h s st p ln l nt yu, sm gy ra sp in p, ko theo mt n nh

ton h thng. Ci thin n nh cho cc nt ny thng nng cao d tr n nh

chung cho ton h thng.

4. H s nhy bin ng cng sut nhnh.

Vi kch bn quan tm tnh c cng sut nhnh ch ban u Pi0 v ch

gii hn Pigh. H s nhy bin ng cng sut nhnh c tnh theo cng thc:

%.100P

PPK

0i

0ighiiNh

=

Nhnh c nhy ln l nhnh nguy him (ct ra s nh hng nhiu n tnh n

nh).

6. Tc bin thin in p v gc lch pha cc nt.

Mc n nh h thng c lin qua n cc o hm dQ/dU v dP/d (tiu

chun thc dng ca Markovits). H thng s mt n nh khi cc o hm ny tin

ti 0. Chng trnh Conus c chc nng kho st s thay i cc h s nhy (tr

s nghch o ca cc i lng ny) trong qu trnh lm bin thin thng s (v

ng cong). Cc yu t gii hn thng c nh hng lm thay i t bin (nhy

bc) ng cong.

5. Min n nh nt ti trong khng gian cng sut nt.

56

Lm bin thin cng sut nt ti theo nhng hng khc nhau c th tm

c cc im nm trn gii hn n nh. ng cong ni cc im s phn chia ra

min n nh v khng n nh trong khng gian cng sut nt.

Min n nh c trng cho kh nng cung cp cng sut t nt (t l vi

rng ca min n nh).

Chng 3

TNH TON B KINH T TRONG LI IN PHN PHI *)

3.1. SUT GIM CHI PH TN THT T THIT B B TRONG LPP

Khi t mt dung lng b Qbj vo nt j trong li in, tn tht cng sut

tng c th thay i mt lng Pj = P1 - P2. Trong P1 v P2 tng ng l

tng tn tht trc v sau khi t b. Chi ph tn tht gim c trong mt nm c

th tnh theo biu thc: Cj = g..Pj [/nm].

Trong : g - gi bn in [/kWh]; - thi gian tn tht cng sut ln nht [h].

Tr s o hm: j = Cj/Qbj c gi l sut gim chi ph tn tht ca thit b b

khi t vo nt j. n v tnh ca l /kVar.nm. C th hiu l khi t mt n v

dung lng b vo nt j th mi nm chi ph tn tht gim c j ng.

Tr s > 0 th hin thit b b c hiu qu gim tn tht, ngc li tn tht b tng

thm. Sut gim chi ph tn tht ca mi nt khng phi l mt con s c nh bi

n ph thuc vo hin trng phn b CSPK trn cc nhnh. Tuy nhin, khi tnh c

sut gim chi ph tn tht cho mi nt s c c s nh gi v hiu qu b trong

li in ang xt:

- Nu mi nt u c m hoc ch c mt s t nt vi dng v nh th nhu cu

t b trong li ny khng c. Khng nn t vn b kinh t.

- Cc nt c tr s dng v cng ln th hiu qu t b cng cao;

- Nt b ch c hiu qu kinh t khi thi gian thu hi vn nh hn tr s chn (vi

thit b b thng chn Tm = 2-3 nm). C th tnh thi gian thu hi vn khi t

thit b b vo nt j theo cng thc: Tthj = k0/j [nm].

Trong k0 - l sut vn u t cho thit b b (tnh bng /kVar).

57

Khi t b nhiu nt, hiu qu b nh hng ln nhau bi phn b CSPK

thay i. Khi tng dung lng b ti mi nt, hiu qu b cng gim dn.

3.2 TNH TON DUNG LNG B KINH T TRONG LI PHN PHI

Bi ton chn dung lng b ti u theo hiu qu kinh t rt phc tp bi ngoi ph

thuc vo cu trc li, cng sut ph ti cc nt, hiu qu kinh t cn ph thuc s

thay i ph ti theo biu . Chng trnh Conus khng t vn tnh ton dung

lng b ti u cho li phn phi m ch to cng c ngi k s c th da

vo tnh ton la chn dung lng b kinh t mt cch hiu qu. C th c cc

kh nng tnh ton sau:

1. Tnh ton sut gim chi ph tn tht v thi gian thu hi vn khi t thm dung

lng b vo mi nt theo ngha nu trn.

Chc nng ny gip s b nh gi hiu qu b trong li cho. Li c

nhu cu b nu c nhiu nt vi ln v thi gian thu hi ngn hn tiu chun (Tth

< 2-3 nm). Ngc li khng nn t vn p dng gii php b.

2. Tnh ton dung lng b kinh t t ti cc nt chn theo ngha m bo thi

gian thu hi vn ca mi nt chn u ngn hn Tm= (2-3)nm.

Chc nng ny gip ngi s dng chn c v tr v dung lng b t hp l

nht. Thng c thc hin theo cc bc sau:

- Chn s b s lng nt s t b (sau khi tnh c v Tth ca mi nt). S nt

c th tng i nhiu nu c nhiu nt vi Tth nh.

- Tnh dung lng b "ti u" cho mi nt.

- Xem xt li tnh hp l ca cc dung lng b nhn c v loi b cc nt hiu

qu km (c dung lng b nh). Tnh li vi s lng nt mi.

quyt nh dung lng t b hp l cho li, c th phi tnh thm vi cc

mc ti khc nhau, xt n kh nng ng ct thit b b ...

-----------------------------------------

Trch t ti liu ngun:

*) "Tnh ton phn tch ch ca HT". Bi ging SH - GS TS L Vn t.

**) " Phn tch v iu khin n nh HT". Bi ging SH - GS TS L Vn t.

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