TaiLieuTongHop.com---Bu Cong Suat Phan Khang Va Thi Truong Dien Nang Phan Khang

7/29/2019 TaiLieuTongHop.com---Bu Cong Suat Phan Khang Va Thi Truong Dien Nang Phan Khang

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B gio dc v o to

i hc thi nguynTRNG i hc k thut cng nghip

DNG ha an

Vn cos, b cng sut phn khng v thTRNG in nng phn khng

Chuyn ngnh: thit b mng v h thng in

Lun vn thc s khoa hc k thut

Thi nguyn nm 2008


2/88

B gio dc v o toi hc thi nguyn

TRNG i hc k thut cng nghip

DNG ha an

Vn cos, b cng sut phn khng vth TRNG in nng phn khng

Chuyn ngnh: thit b mng v nh my in

Lun vn thc s khoa hc k thut

Ngi hng dn khoa hc: PGS.TS. Phm Vn Ha

Thi nguyn nm 2008


3/88

S ha bi Trung tm Hc liu i hc Thi Nguyn http://www.lrc-tnu.edu.vn

2

LI NI U

Cng vi qu trnh pht trin kinh t x hi ca t nc, ngnh in lun phi i

trc mt bc trong cng cuc cng nghip ha v hin i ha. Cc nh my x

nghip, cc khu cng nghip ngy cng pht trin nhanh chng i hi tiu th cn g

sut phn khng cng tng, iu ny lm gim h s cos , gim cht lng in

nng, tng tn tht.V vy cc h tiu th in b p dng bng gi pht i khi c h

s cos thp.

Ni dung ca lun vn gm hai vn chnh :

- i nghin cu phng php xc nh dung lng t thit b b, v tr tb, nhm em li hiu qu ti u c v kinh t v k thut.

- Nghin cu th trngin nng phn khng.

ti Vn cos , b cng sut phn khng v th trng in nng phn

khng gm bn phn nh sau:

1. Tng quan .

2. Chng trnh tnh ton b ti u cng sut phn khng, c xt n cht lng

in nng v phn tch kinh t ti chnh.

3. Tnh ton p dng:

4. Th trng in nng phn khng.

5. Kt lun v kin ngh.

Trong sut qu trnh thc hin lun vn, ti nhn c s gip v ch bo

tn tnh ca PGS.TS Phm Vn Ha, ti xin chn thnh cm n nhng ng gp ca

thy gio hng dn, cc thy c gio trngi hc bch khoa H Ni, v cc thyc gio trngi hc Cng nghip Thi Nguyn. Ti cng xin chn thnh cm n

nhng ng gp qu bu ca cc bn ng nghip, ngi thn v gia nh ng

vin v gip ti trong qu trnh thc hin. Xin gi li chn thnh cm n n cc c


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3

quan x nghip, gip ti kho st tm hiu thc t v ly s liu phc v cho lun

vn.

Mc d bn thn c nhiu c gng, song bn lun vn ny vn cn nhiu hn ch,

ti rt mong c s ch bo, gp ca cc thy c v cc bn ng nghip lun

vn ny c hon thin hn.

Xin chn thnh cm n.

Thi Nguyn ngy thng nm 2008


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4

Mc lc

Li Cam oan.....1

Li ni u:....2Mc Lc:....4Chng I: TNG QUAN.......7

1.1Vn b cng sut phn khng trong h thng in:....7

1.2 Ngun cng sut phn khng:... 8

1.3.B kinh t cng sut phn khng:...9

1.4. Phn tch nh hng ca t b n tn tht cng sut tc dng v tn tht

in nng li phn phi:..........10

1.4.1 li phn phi mt ph ti:.10

1.4.2 Li phn phi c ph ti phn b u trn trc chnh.14

1.5 Mt S phng php tnh b cng sut phn khng: .......16

1.5.1 Phng php xc nh dung lng t b theo biu cng sut phn

khng ca ph ti :

1.5.2 B cng sut phn khng nng cao h s cos :....19

1.5.3 M hnh b cng sut phn khng theo iu kin cc tiu tn tht cngsut:..20

1.5.4 M hnh b cng sut phn khng da trn ch tiu ti a ha cc tit

kim..23

1.5.5 M hnh tnh b theo iu kin chnh in p..24

1.5.6 M hnh b cng sut phn khng da trn ch tiu cc tiu hm chi ph

tnh ton..26

1.5.7 Phng php xt n nhy ca chi tiu n nh in p, lch in

p v tn tht cng sut tc dng i vi s bin i cng sut phn khng

nt.......28

1.5.8 M hnh quy hoch hn hp..... ..31

1.6. Tm hiu cos v b cos ti mt s nh my x nghip...32


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5

1.6.1 Cc ph ti tin hnh iu tra..33

1.6.2.Mt s nhn xt t kt qu thc t.33

1.6.3 Tm tt v kin ngh ........................................................................38

Chng II: -CHNG TRNH TNH TON B TI U CNG SUT PHN

KHNG, C XT N CHT LNG IN NNG V PHN TCH KINH T

TI CHNH................................................................39

2.1. Phng php lun v s khi thut ton..39

2.1.1 M hnh tng qut bi ton b cng sut phn khng trong li phn

phi:.39

2.1.2. Hm mc tiu....402.1.3 Cc rng buc...... 42

2.1.4 M hnh bi ton b cng sut phn khng khi c xt n my bin p:

..43

2.1.5 Mt s gi thit khi tnh ton ti u cng sut b:..44

2.2 Phng php gii bi ton b cng sut phn khng.44

2.2.1 Tng quan44

2.2.2. Thut ton gii bi ton b cng sut phn khng bng phng php quy

hoch ng:.45

2.2.3 Xt n rng buc v in p:.48

2.2.4.Hnh thc ho thut ton v s khi.48

2.2.6 Cc s liu cn a vo tnh ton:.50

2.2.7 V d p dng .51

2.3. Chng trnh my tnh v s dng chng trnh ....53

Chng III- TNH TON P DNG:.......58

3.1 S l 677: ..........................................................................................583.2 Cc S liu Tnh ton:............................................................................59

3.3 Kt qu tnh ton ng vi ch ph ti cc i:..61


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6

3.4 Phn tch kinh t ti chnh v nh gi hiu qu kinh t b cng sut phn

khng...............................................................................................................65

Chng 4: TH TRNG IN NNG PHN KHNG.................... ...........69

4.1Th trng in nng phn khng vit Nam:..........................................69

4.1.1 Phn tch m hnh kinh doanh in nng phn khng hin ti

Vit Nam:................................................................................................69

4.1.2 Phng php xc nh tin mua cng sut phn khng:.................. 70

4.2 Cc m hnh kinh doanh in nng c th c p dng:......................74

4.3V d p dng:.............80

Chng V : KT LUN V KIN NGH...............845.1 Kt lun : ...............................................................................................84

5.2 Kin ngh:...............................................................................................84

Ti liu tham kho.............................................................................................86


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7

CHNG I ;

TNG QUAN

1. VN B CNG SUT PHN KHNG TRONG LI IN:1.1 Vn b cng sut phn khng trong h thng in:

Trong h thng in lun c phn t tiu th v ngun pht cng sut phn

khng. Phn t tiu th l my bin p, ng c khng ng b, trn ng dy in

v mi ni c t trng. Yu cu cng sut phn khng ch c th gim ti thiu ch

khng trit tiuc v n cn thit to ra t trng, yu t trung gian trong qu

trnh chuyn ha in nng. yu cu cng sut phn khng c phn chia nh sau:

- ng c khng ng b tiu th khong 70-80%.

- My bin p tiu th 25-15%.

- ng dy ti in v cc ph ti khc 5%.

Kh nng pht cng sut phn khng ca cc nh my in rt hn ch,

cos = 0,8-0,85. Cc my pht ch m ng mt phn yu cu cng sut phn

khng ca ph ti. Phn cn li trng vo cc ngun cng sut phn khng t thm

tc l ngun cng sut b.

C 2 con ng m bo cn bng cng sut phn khng trong h thng in :

(1) - Cng bc ph ti m ch yu l cc x nghip cng nghip phi m

bo cos ca h mc cho php. Cch ny nhm gim yu cu cng sut phn

khng.

(2)- t b cng sut phn khng trong h thng in gii quyt phn thiu

cn li.

Tm li trong h thng in phi b cng bc hay b k thut mt lng cng sut

phn khng nht nh m bo cn bng cng sut phn khng trong h thng

in.

H thng in thiu cng sut phn khng th vic b k thut l bt buc, gi l b

cng bc.


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8

Sau khi b cng bc, mt lng cng sut phn khng ng k vn lu thng qua

li phn phi trung p gy ra tn tht cng sut tc dng v tn tht in nng kh

ln.

gim tn tht ny c th thc hin b kinh t.

B kinh t ch c thc hin khi n thc s mang li li ch, ngha l li ch kinh t

m n mang li phi ln hn chi ph vn hnh v lp t trm b.

Trong cc x nghip cng nghip lng cng sut phn khng phi b cng bc

m bo cos cng c phn phi hp l nhm gim ti a tn tht in nng.

1.2 Ngun cng sut phn khng:V ngun cng sut phn khng thy rng: Kh nng pht cng sut phn

khng ca my pht rt hn ch. V l do kinh t ngi ta khng lm cc my pht

c kh nng pht nhiu cng sut phn khng cho ph ti, c bit l ch

max. Cc my pht ch m ng mt phn yu cu cng sut phn khng ca ph

ti, ch yu lm nhim v iu chnh cng sut phn khng trong h thng in p

ng nhanh chng cc yu cu lun thay i ca ph ti. Phn cn li trng vo cc

ngun cng sut b.

C hai loi ngun cng sut phn khng l my b ng b v t in.

-T in c s dng rng ri b cng sut phn khng trong mng in, n c

th mc trn thanh ci ca cc trm bin p, hoc ti cc im nt ca mng in. T

in c th mc c lp hoc mc thnh tng nhm theo yu s u Y, hoc u

tam gic.

Hnh 1.1 S mc t b tnh

i vi li in hin nay ch yu s dng t in tnh do cc u im sau:

S=P+jQQC

~


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9

- Chi ph theo 1 Var theo t l r hn so vi my b ng b.

- Lm vic m, tin cy do kt cu n gin.

- Tui th cao.

- Tiu th tn sut tc dng t.

- Lp t v vn hnh n gin .

Tuy vy t in cng c nhc im so vi my b ng b :

- My b ng b c th iu chnh trn cng sut phn khng cn t in iu

chnh theo tng cp.

- My b ng b c th pht ra hay tiu th cng sut phn khng cn t in

ch c th pht cng sut phn khng .- Cng sut phn khng do t in pht ra ph thuc vo in p vn hnh, d

h hng ngn mch.

bo v qu in p v kt hp iu chnh t b theo in p, ngi ta thng lp

t cc b iu khin ng ct t theo in p. T cc u im trn ngy nay

thng dng t in tnh b cng sut phn khng.

1.3.B kinh t cng sut phn khng:

1.3.1 Tn tht cng sut v tn tht in nng:

B kinh t l phng php gim tn tht cng sut v tn tht in nng hiu

qu. Tn tht gm hai loi :

+ Tn tht k thut l tn tht sinh ra do tnh cht vt l ca qu trnh ti in, tn

tht ny ph thuc vo tnh cht ca dy dn v vt liu cch in, iu kin mi

trng, dng in v in p.

Tn tht k thut chia lm 2 loi :- Tn tht ph thuc vo dng in: Sinhra do s pht nng trn in tr ca my

pht, my bin p v dy dn. Thnh phn ny l tn tht chnh.

-Tn tht ph thuc vo in p gm c: tn tht trong li thp ca my bin p, tn

tht do r in, do vng quang.

Tn tht k thut khng trit tiu c m ch c th hn ch mc cho php.


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+ Tn tht kinh doanh : L tn tht trong khu kinh doanh in nng do: in nng

tiu dng khng o c, in nng o c nhng khng vo ha n, in nng

vo ha n nhng khng c tr tin hoc tr chm.

1.3.2 Phng thc b kinh t cng sut phn khng trong li phn phi v bi

ton b kinh t:

Li ch khi t b :

- Gim c cng sut tc dng yu cu ch d max ca h thng in do gim

c d tr cng sut tc dng hoc tng tin cy ca h thng.

- Gim c tn tht in nng.

- Ci thin c cht lng in p.- Gim nh ti cho my bin p trung gian v ng trc trung p gim c yu cu

cng sut phn khng, tng tui th cho thit b.

Chi ph khi t b:

- Vn u t v chi ph vn hnh cho trm b.

- Tn tht in nng trong t b.

Gii bi ton b cng sut phn khng l xc nh : S lng trm b, v tr t ca

chng trn li phn phi, cng sut b v ch lm vic ca t b sao cho t

hiu qu kinh t cao nht.


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1.4. Phn tch nh hng ca t b n tn tht cng sut tc dng v tn tht

in nng li phn phi :

1.4.1 li phn phi mt ph ti:

Xt li phn phi theo hnh 1.2 a cng sut phn khng yu cu max l Q max

, Cng sut b l Qb th ko di ca cng sut phn khng yu cu l q(t), th

ko di ca cng sut phn khng sau khi b l : qb(t)= q(t)- Qb

-Trn hnh 2.1 b : qb1(t) ng vi Qb=Qmin.

-Trn hnh 2.1 c : qb2(t) ng vi Qb=Qtb.

-Trn hnh 2.1 d : qb1(t) ng vi Qb=Qmax.

T cc th ko di ca cng sut phn khng ta thy: khi t t b th ko dicng sut phn khng mi c th nm trn, nm di hoc ct trc honh ty thuc

vo ln ca cng sut b. Cng sut phn khng dng c ngha l n i t

ngun n ph ti cn m c ngha l i ngc t ph ti v ngun. D i theo

hng no cng sut phn khng u gy ra tn tht cng sut tc dng nh nhau

nu ln nh nhau.

Trong trng hp Qb=Qmin(hnh 1.2 b) th trong cc ch tr ch min

ph ti phi nhn cng sut t ngun, cn trong ch max ch gim c lng

cng sut phn khng Q=Qmax- Qb=Qmax-Qmin.

Trong trng hp Qb=Qmax ( hnh 1.2 d) th trong cc ch tr ch max, cng

sut b tha cho ph ti v i ngc v ngun. Cng sut phn khng yu cu ch

max c trit tiu hon ton, cho li ch ln nht v gim yu cu cng sut

phn khng v tn tht cng sut tc dng.


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a)

Hnh 1.2

V mt tn tht in nng hai trng trng hp ny ging nha u hon ton, ta

thy th cng sut phn khng ca chng c dng ging nhau ch ngc du mthi.

Trong trng hp Qb=Qtb(hnh 1.2 c), trong 1 na thi gian cng sut phn khng i

t ngun n ph ti cn trong na thi gian cn li cng sut phn khng i t t b

i ngc v ngun. Yu cu cng sut phn khng khng gim c nhiu nhng

Qmax Qmaxqb1(t) Qb=Qmax Qb=Qtb

Qtb+

0 0 -

b) T c) qb2(t) TQmin

QmaxQb=Qmax

Qmin

d) 0

qb3(t) - T

+ cng sut phn khngn ti.- cng sut phn khng iv ngun.

R Qmax [KVAr]

Qb[KVAr]


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th ny cho tn tht in nng nh nht c ngha l gim tn tht in nng ln

nht. Bi v tn tht in nng ph thuc vo bng phng ca th cng sut

phn khng, th cng bng phng th tn tht in nng cng nh (theo nguyn tc

bnh phng cc tiu).

Tm li nu cho php b khng hn ch th :

-Qb=Qmax cho gim tn tht cng sut tc dng v gim yu cu cng sut

phn khng ch max ln nht.

-Qb=Qtbcho gim tn tht in nng ln nht. Kt lun ny l tng qut ng cho

mi cu trc li phn phi.

Nu xt ng thi cho c hai yu t th cng sut b ti u s phi nm u giaQmin v Qtb.

Cc nhn xt trc quan trn y s c lng ha chnh xc di y phc v

gii bi ton b sau ny.

Tn tht cng sut tc dng do cng sut phn khng q(t) gy ra l:

RU

tqP

2

2)(

[ KW, MVAr, ,KV] U l in p nh mc ca li in.

Sau khi b:

RU

QQtqtqR

U

QtqP bbbb

22

2

2)(.2)())((

L ch v tn tht cng sut tc dng sau khi b chnh l gim tn tht cng suttc dng do b:

22

2))(.2(.).(.2

)(U

QtqQRR

U

QQtqPPtDP bbbbb (1.1)

Li ch do gim tn tht cng sut tc dng ch c ngha ch max ca h

thng khi m ngun cng sut tc dng b cng thng, lc q(t)=Qmax v:

RU

QQtQDP bb

2

2

max ).(.2 (1.2)

Ta d thy DP s ln nht khi Qb=Qmax.

RU

QDP

2

max2

max


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14

gim tn tht in nng trong thi gian xt T l tch phn ca DP(t) trongkhong thi gian xt T:

2

max

22

2

2

0

2

).2(..].2[.....2..]).(.2[

U

QQKQRT

U

QQQRT

U

QTQTQ

U

dtRQQtq

DAbsdqbbtbbbbb

T

bb

(1.3)

V tbQdttqT)(

1v Ksdq=Qtb/Qmax.

Ly o hm ring ca 1.3 theo Qb, t =0 ri gii ta c gi tr ca Qbcho gim

tn tht in nng ln nht:

02.22

RU

QTQ

Q

DA btb

b

rt ra Qbopt=Qtb Khi

2

2

maxUQRTDA tb

Cn lu rng c th gii bi ton b, trc ht phi tin hnh o c th cng

sut phn khng trn li phn phi d nh t b m bo b em li hiu qu

thc s.

1.4.2 Li phn phi c ph ti phn b u trn trc chnh :

Xt li phn phi trn hnh di y :

a)

b)

Hnh 1.3

QN

0 B C AL

0 r0[ /km] 0[KVAr/km]

Qblb


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15

Trong trng hp ny c vn l a im t b nn u c hiu qu

b l ln nht. Cn vn gi tr cng sut b c gii quyt phn trn v vn

ng cho trng hp ny.

Gi thit rng ch t b ti 1 im v phi tm im t ti u sao cho vi cng sut

b nh nht t hiu qu ln nht.

Ta xt ch max :

Tn tht cng sut trc khi b l :

).3/(..232

001ULqrP

Ta t b sao cho cng sut phn khng QNt ngun cp cho on lx(on 0B) cn

t b cung cp cng sut phn khng Qbcho on L-lx(on BA )QN=lx.q0

Qb=(L-lx).q0

D rng nhn thy rng mun tn tht cng sut tc dng v tn tht in nng sau

khi b l nh nht th trm b phi t chnh gia on c, cng sut phn khng

ca t s chia u v 2 pha c di (L-lx)/2 v cng sut phn khng Qb/2. V tr

b s l:

lb= lx+ (L-lx)/2=(L+lx)/2

Tn tht cng sut tc dng trn on lx l:

2

0

2

0

3

2

0

2

0

.3

..

.3

..).(

U

rql

U

rlqlP xxxN

Tn tht cng sut tc dng trn on L-lx l:

2

0

2

0

3

2

02

0.12

..)(

.6

).(.]2/)..[2

U

rqlL

U

rlLqlLP xxxb

Tn tht cng sut tc dng sau khi b l:

..3].4/)([.12

)().3/(..2332

002

2

03

0

2

0

23

2UlLlqr

U

qlLrUrqlPPP xxxoxbN

gim tn tht cng sut tc dng do b l:

]4/)([.3

.

.3

. 332

0

2

03

2

0

2

021 xx lLl

U

rqL

U

rqPPDP (1.4)


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16

Ly o hm ca DP theo lxri t =0 v gii ta c lxop.

0]4/)(3.3[.3

. 222

0

2

0

xx

x

lLlU

rq

l

DP

3

Llbop

T y ta c v tr b ti u3

2Llxop

Nh vy mun gim tn tht cng sut tc dng do b ln nht ngun in phi

cung cp cng sut phn khng cho 1/3 di li in, t b cung cp cng sut

phn khng cho 2/3 cn li v t v tr cc u li in 2/3L. Ty cng tnh

c cng sut b ti u l 2/3 cng sut phn khng yu cu.

D dng chng minh c rng c gim tn tht in nng ln nht vn

phi t b ti 2/3 L nhng cs b ti u l 2/3 cng sut phn khng trung bnh.

Trong li in phc tp v tr b ti u c th x dch mt cht so vi li in n

gin xt y.

Hai trng hp n gin trn cho thy r v cc khi nim nh :

gim tn tht cng sut tc dng, gim tn tht in nng do b, cng

sut b ti u theo cc iu kin gim tn tht cng sut tc dng, Gim tn

tht in nng, v tr t b cng nh iu kin cn gii bi ton b.

1.5 Mt S phng php tnh b cng sut phn khng :

1.5.1 Phng php xc nh dung lng t b theo biu cng sut phn

khng ca ph ti:

Dung lng t b c nh :Q

bc=Q

min(KVAr) (1.5)

Dung lng t b ng ct xc nh :

7.0max

)(

Q

Q ngctcib(1.6)

Hoc tng dung lng (T c nh +t ng ct) l dung lng cn thit nng

in p im nhn n cc i ch 50% ti nh.

*Kim tra iu kin in p:


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17

in p t c khng vt qu ch ti cc tiu.

Khi c biu cng sut phn khng ca ph ti c th xc nh d dng dung

lng t b theo phng php ny. y cng l phng php n gin xc nh

dung lng t ng ct trn li nhm m bo cho iu kin v chnh lch in

p ti h dng in. Tuy nhin phng php ny ch cho php xc nh khong thi

gian cm t ng vo hoc ct ra khi li do chnh xc khng cao, n ph

thuc vovic ly s liu ban u trong yu cu chnh xc l tng i cao.

Hnh di y cho cch xc nh dung lng t b p ng nhu cu cng sut phn

khng .

*u im: n gin, d p dng.

*Nhc im:


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18

- Phi c biu cng sut phn khng ca ph ti, y l iu kh khn bi cc

trm phn phi chim ti trng ln trong tng s trm bin p m li cha c cc

ng h in t, cc ng h cm ng khng p ng c cc yu cu s liu,

khng c ngi trc tip ghi thng s theo gi, do cn phi c thi gian di

theo di nm quy lut dn n chnh xc khng cao.

-Ph ti phi c quy lut tng i n nh, cc ph ti trong mng li tng i

ng nht, iu ny kh xy ra trong thc t.

-Cha tnh n kh nng iu p ca cc MBA c iu p di ti nn c th gy

qu p cc gi thp im (non ti).

-Cha xt n hiu qu kinh t ca vic b cng sut phn khng. 1.5.2 B cng sut phn khng nng cao h s cos :

Bng cch t cc thit b b ti cc h dng in cung cp cng sut phn khng

cho chng, ta gim c lng cng sut phn khng phi truyn ti trn ng dy

do nng cao c h s cos ca mng. Nhng bin php b cng sut phn

khng khng lm gim lng cng sut phn khng tiu th ca cc h ph ti m

ch gim c lng cng sut phn khng truyn ti trn ng dy m thi. V

th ch sau khi thc hin cc bin php nng cao cos t nhin m vn khng t

yu cu th chng ta mi xt n phng b nay.

Dung lng b c xc nh theo cng thc:

Qb= .P.(tg 1- tg 2) [KVAr] (1.7)

Trong :

-P l ph ti tnh ton ca h tiu th in KW.

- 1 l gc ng vi h s trung bnh (cos 1) trc khi b.- 2 l gc ng vi h s cng sut mong mun (cos 2) sau khi b.

- = 0.9 1 l h s xt ti kh nng nng cao cos bng nhng phng php

khng i hi t thit b b.


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19

ng v mt tn tht cng sut tc dng ca h dng in th dung lng b c th

xc nh theo quan im ti u.

Do b c th tit kim c mt lng cng sut tc dng:

DP=(Kkt-kb). Qb [KW] (1.8)

Trong :

Kkt ng lng kinh t ca cng sut phn khng, KW/KVAr (l lng

cng sut tc dng (KW) tit kim c khi b 1 KVAr.

)2(2 Q

Q

U

QR

Q

DPK b

b

p

kt (1.9)

DPp lng gim tn tht cng sut tc dng do cng sut phn khng gy ra khit mt n v cng sut b.

KW/KVAr.

Q- Cng sut phn khng h tiu th, KVAr.

Nu Qb


21/88


20

T cng thc 1.9 rt ra thnh phn U2/(2R) v thay vo cng thc trn ta c:

)1(kt

b

boptk

kQQ [KVAr] (1.12)

Qboptkhng nht thit trng vi Qbc tnh theo cng thc 1.7, ng v

pha cc h tiu th th nn b mt lng bng Qboptl kinh t hn c, song do li

ch chung ca ton h thng in, thng nh nc quy nh h s cng sut tiu

chun m cc h tiu th nht thit phi t c, mc d i vi tng h dng in

c th cos tiu chun cha phi l tt nht.

V vy, trong thc t ngi ta thng tnh dung lng b theo cng thc (1.7)

Phng ny c bit n gin, d p dng nn c s dng rng di, bit cng sut

P, h s cos 1ca ph ti, h s cos 2yu cu ta c th tnh nhanh c lng cng

sut phn khng cn b. Vn t ra l phn phi dung lng b ra sao cho t

hiu qu kinh t nht, thng cc bi ton ny tin hnh theo nguyn tc m bo

tn tht cng sut tc dng P do cng sut phn khng gy ra l nh nht. Trong

cc x nghip cng nghip, mng in thng l hnh tia hoc phn nhnh v vy

vic phn phi dung lng b theo nguyn tc trn c th thc hin d dng.* u im: n gin, d p dng, d ly s liu.

* Nhc im : M hnh ny ch thch hp vi li in x nghip cng nghip l

li c ph ti phn khng cao, h s cos thp.

1.5.3 M hnh b cng sut phn khng theo iu kin cc tiu tn tht cng

sut:

Bng vic gii tch mng in, tnh ton phn b cng sut, ng vi mi ch xc

lp, ta tnh c in p ti cc nt v tn tht P, Q ca h thng. Trong tn

tht cngsut ca nhnh i ca mng in c xc nh theo cng thc:

3

2

22

10.. ii

iii R

U

QPP [KW] (1.13)


22/88


21

3

2

22

1 10.. ii

ii XU

QPQ [KVAr] (1.14)

Vi Si=Pi+jQil cng sut i vo nt i trn nhnh i, KVA. Zi=Ri+jXil tng tr ca nhnh, .

Khi t mt gi tr b Qivo nt i, cc biu thc(1.13) (1.14) tr thnh

3

2

22

1 10..)(

i

i

biii RU

QQPP (1.15)

3

2

22

110..

)(i

i

biii XU

QQPQ (1.16)

Xem Pi v Qil cc hm mc tiu vi bin Qbibi ton b ti u cng sut phn

khng theo cc tiu tn tht cng sut tc dng nhm mc tiu gim tn tht in

nng c pht biu nh sau:

Tnh chn cc gi tr Qbiti cc nt i sao cho P (Qbi) min vi cc rng buc

in p ti cc nt m bo t gi tr ln cn gi tr nh mc v vi cc iu kin

bin Qb min Qb Qb max .

Vi bi ton gii tch mng in c n nt, cc hm F(Qbi)= P(Qbi) tr thnh

hm a bin vi i=1 n.

Bi ton b ti u cng sut phn khng theo iu kin cc tiu tn tht cng

sut tc dng c pht biu nh sau:

Cn xc nh cc gi tr Qb1,Qb2,.Qbn sao cho:

F(Qb1,Qb2,.Qbn)= P(Qb1,Qb2,.Qbni) min

Vi cc iu kin bin: Qb min Qb Qb max . (1.17)Trong Qbi - Gi tr b ti u ti nt i.

Qb min, Qb max _- Cc gi tr gii hn b min v b max ti nt i.

F(Qbi)tn tht cng sut ng vi gi tr Qbit ti nt i.


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22

12

1

2

1

2

1 .)(

)()( RU

QQPQPQF biibi (1.18)

Cc rng buc trong bi ton ti u l nh lut Kirchof 1 cho cng sut phn khngti cc nt c yu cu b v cng.

11

bnb2b1 ).Q,Q,Q(m

I

jj Ig (1.19)

T y thnh lp hm lagrange:m

i

jin gFL1

bnb2b1bnb2b1321bnb2b1).Q,Q,Q().Q,Q,Q()....,;.Q,Q,Q(

Trong jvi j=1,2,3,m l nhng hng s khng xc nh Lagrange. y l mt trng hp ca bi ton quy hoch phi tuyn, trong cc rng buc c

quan h tuyn tnh, hm mc tiu l tng ca cc hm c quan h tuyn tnh v quan

h bc 2. p dngphng php Lagrange gii bi ton trn, tm nghim ca

phng trnh L(Qbi, j).

Xem xt cc hng s jLagrange l bin, ly o hm ring phn biu thc

trn ln lt theo cc bin Qbi v jta c h phng trnh:

bi

m

j j

i

j

bi

j

m

j bi

i

bi

bi

bi

Q

L

gQPL

Q

g

Q

QP

Q

L

2

2

1

1

)(

)(

Vi i=1 n; j=1 n. (1.20)

Gii h (m+n) phng trnh trn kt hp vi iu kin bin ta tm c n nghimQbiv nghim j.

Nhn xt phng php:

u im: Bi ton hi t nhanh, li gii vi mng c s nt, nhnh khng ln lm

tm c kh d dng, c th m rng thnh m hnh ph thuc in p nng cao

chnh xc ca kt qu.


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* Nhc im: Cha nhn xt n iu kin v in p cc nt; vi mng in c

nhiu nt, nhiu nhnh th khi lng tnh ton ln, vic ly o hm dng gii tch

rt kh khn.

1.5.4 M hnh b cng sut phn khng da trn ch tiu ti a ha cc tit

kim:

Theo yu cu l ti u dung lng v v tr lp t ca n t b trn mt xut tuyn

phn phi ba pha hnh tia nhm ti thiu ha tn tht cng sut v tn tht in nng.

C th hn l chng ta tm cc v tr h i (i=1,2,n) v cc kch c Qbi(i=1,2n) ca

cc t b ngang theo hnh 1-5 cc i ha cc tit kim rng bng tin t c

cho chng trnh lp t t.

Hnh 1.5 V tr lpt v kch ctin

Cc tit kim rng tc t gim tn tht cng sut v tn tht in nng :

S= CpDP +C .DA-Kc Qbi (1.21)

Vi Cp, C , Kcl cc h s kinh t, gi ca mi n v tn tht cng sut, tn tht

in nng v dung lng t b.

DP, DA- gim cng sut nh, gim tn tht in nng do tc dng ca

n t b ngang.M hnh ny c th gii bng phng php lp cho tng bi ton nh, tm bin

ti u cc b (v tr, kch thc, thi gian ng ct ti u) t xc nh li gii ti

u ton cc.

Pi+jQi QbPn+jQn Qbn


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24

* u im: Tnh c tng i cc li ch do thit b b mang li, c

bit c ngha vi mng li lm vic tng i y ti, do gim c lng cng

sut tc dng gi cao im.

* Nhc im: chnh xc ca m hnh ph thuc rt nhiu vo cc h s

kinh t.

- Vic xc nh cc h s Cp, C , Kcl rt kh khn, ngoi ra trong thc t gi tr t

b l hm khng tuyn tnh i vi dung lng ca n.

-Cha kim tra c iu kin v lch in p.

M hnh kh phc tp nn trong thc t phi ty theo iu kin c th ngi

ta c th a ra cc gi thit lm n gin m hnh. V d: Nu mc ch ca chngtrnh lp t t l gim ti a tn tht cng sut nh th C ,=0, ( cng thc 1.21

), cn nu mc ch l tit kim in nng (gim tn tht in nng), khng

n tn tht cng sut hay tnh kinh t th c h s Cp=0, , Kc=0,

1.5.5 M hnh tnh b theo iu kin chnh in p:

Trc khi b tn tht in p trong mng l:

)(100

12 iiii

nXQRPUU (1.22)

ly cho ton ng dy.

Sau khi tn tht in p gim i mt lng l:

i

n

b XU

U2

100

1(1.23)

ly im t b.

Sau khi b: U= U- Ub

Bn cht vn khng thay i nu ta coi tn tht U ca li vn gi

nguyn nhng a thm vo u ngun mt tng in p Ek:

ib

n

bk XQU

UE2

100

1(1.24)


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25

Nu bit Ekta tnh c Qb, vi ng dy cng tit din:

XEUQ knb /.102

[KVAr] (1.25)

X- l in khng ca ng dy tnh n im b, .Nu cng sut cn b qu ln th c th chia ra lm nhiu im t b (hnh 1.6). Ta

c phng trnh: knbb EUXQXQ2

2211.10...... (1.26)

Hnh 1.6 Phn phi cng sut t b trong mngin

Trn c s phn tch, so snh cc phng n ta s la chn c a im t dung

lng b hp l.

*u im: n gin, c th d dng xc nh c dung lng t khi bit dung

lng tng thm in p.

- Do t b theo iu kin in p nn c th b su c, lm gim ng k

tn tht trong mng.

-

C th kt hp vi chn nc iu chnh my bin p c dung lng bl b nht.

*Nhc im: im t b kh phn tn gy kh khn cho vic vn hnh v iu

chnh dung lng.

- Vi lng in bao gm nhiu nt, nhnh, s phng n t b s ln, vic tm ra

li gii v im t b v dung lng ti u tng i phc tp.

Xi

Qb1 QbiQbn

X1


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26

- Khng xt ti yu t kinh t ca vic lp t t.

1.5.6 M hnh b cng sut phn khng da trn ch tiu cc tiu hm chi ph

tnh ton:

Xt mng in gm n nt (khng k nt ngun cung cp), i vi mi nt i,

k hiu cng sut cc i ca ph ti S ti=Pti+jQti cng sut b Qbi , i vi mi

nhnh i tng tr Zi=Ri+jXi, cng sut truyn ti n cui ng dy: S i=Pi+jQi (v

mng c s h nn lun c th k hiu th t nhnh theo s hiu nt ca n).

Tn tht cng sut tc dng trn nhnh th i xc nh theo cng thc:

23

2

22

32.10.10...3 iiii

i

iiii QBAR

U

QPRIP [KW] (1.27)

Vi Pi, Qi, Uiu c tnh cui nhnh; Khi tnh gn ng c th ly U i Un (in

p nh mc ti nt i). Tn tht cng sut trong ton mng s l:

n

i

iii QBAP1

2).( [KW] (1.28)

Ai,Bi l nhng hng s.

Gi l thi gian tn tht cng sut ln nht, C l gi tr tn tht ly bng gi bn

in trung bnh, ta tnh c chi ph tn tht hng nm:

P. . C [ng/nm] (1.29)

Vn u t cho thit b b ti nt i:

Vi=koi+KiQbi[ng] (1.30)

Trong : Kil sut vn u t tnh cho mt n vcng sut b, /KVAr.

koil phn vn ph thuc vo dung lng b ng/trm.

Vn u t cho thit b b:n

i

biii

n

i

i QkkVV1

0

1

)( (1.31)

Dng hm mc tiu l cc tiu chi ph tnh ton ta c :


28/88


27

min)].(.)..([.1

2

0

n

i

iiibiiitctc QBACQkykaCVaZ (1.32)

Cn ch koi 0 ch khi Qbi 0, ngc li koi=0. th hin iu ny trong hm mc

tiu c th s dng cc bin nguyn yivi :

01

00

bi

bi

ikhiQ

khiQy (1.33)

atch s tiu chun thu hi vn u t ban u.

y l trng hp ring ca hm phi tuyn, c cha cc im ri rc ti gc

ta . H rng buc cn thit lp bao gm :

- Mi nt c phng trnh cn bng cng sut phn khng dng :

0).(2

k

kkkktibi QDCQQQQ (1.34)

Vi i=1,2n.

Tng k ly ng vi cc nhnh xc nh theo thng s nhnh :

k

n

kk X

U

PC

2

2

2n

kk

U

XD (1.35)

-Gii hn dung lng b ti cc nt c th vit di dng:

Qbi min Qbi Qbi maxvi i=1,2..n. (1.36)

- Gii hn v tng vn u t cho thit b b :n

i

biii VQkk1

0 )( (1.37)

-Gii hn v thi gian thu hi vn :V-(C-C0). T th 0 (1.38)

Trong : C0chi ph tn tht hnh nm khi cha tnh b.

Trong bi ton c gii theo phng php quy hoch phi tuyn xp x hoc

phng php tuyn tnh ha, sai s ca php xp x c th khng ch c theo yu

cu .

*u im:


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28

-Do tnh tng quan ca m hnh nn c th p dng hiu qu xy dng gii bi

ton b kinh t ti u i vi h thng phn phi in.

- Cc rng buc kh ton din, c xt n kh nng u t v mc thu hi vn bt

buc (t hiu qu kinh t cao).

-Phng php cho php u t hiu qu: Vn u t thp nhng c kh nng gim

tn tht vi t l cao.

* Nhc im:

- Khi lng tnh ton ln. S dng rng buc cn bng cng sut phn nt i vi

lng phn phi c nhiu ph ti c tnh cht hn hp l kh thc hin.

- Cha thy r hiu qu ci thin cht lng in (cha c phn kim tra li iukin in p cc nt ph ti).

-Rt kh xc nh cc h s kinh t (v chng ph thuc nhiu vo cc yu t kinh t

x hi khc).

-Khi gi thnh lp t thit b b cao c th tnh n vic tnh dung lng b theo

phng php ny khng t hiu qu ti u.

1.5.7 Phng php xt n nhy ca chi tiu n nh in p, lch in p

v tn tht cng sut tc dng i vi s bin i cng sut phn khng nt:

Cc bc tnh:

- Sp xp cc nt theo th t tin theo nh hng ca s bin i cng sut

phn khng nt n n nh in p, lch in p v tn tht cng

sut tc dng.

- Lp ba vct gi c thch hp cho tng nt, cho tng s bin i cho in p,

cng sut phng khng v du phn p.- Lp hm Lagrangev gii nt ny tm ra nt cn b v cng st b ti

thiu.

Khi gii tch li in bng phng php Newton-Raphson ta c h phng trnh:


30/88


29

U

QQU

PP

Q

P U (1.39)

Nu coi P/ U=0, Q/ =0, ta c :

[ Q]= P/ U=0. [ Q]=[JQ]. [ U] (1.40)

Trong ma trn Jacobi J ch bao gm cc nt ti ;

n nh in p c nh gi theo tiu chun: Hiu ng iu chnh in p

theo cng sut phn khng ca cc nt ti i : Q/ U. Tnh Q/ U cho tng nt ti

sau sp xp nt ti theo tng ca Q/ U . Nu b cc nt c Q/ U thp, v

kh nng n nh in p cc nt ny thp. Q/ U l thnh phn nm trn ng

cho ca ma trn Jacobi JQ.

Ch tiu lch in p c st theo nh hng ca bin i cng sut phn

khng nt n mun in p nt v cc nt ln cn. Khi c cng sut phn khng

mt nt no bin i th s nh hng n mun in p ca tt c cc nt, nh

hng ny th hin trn ct ca ma trn Jacobi J, do phi lp ra tiu chun

nh gi nh hng ny. Nn b cc nt m s bin i cng sut phn khng

nt nh hng nhiu n mc in p ca h thng, do nt c sp xp theo

iu kin ny .

Tn tht cng sut tc dng ph thuc bin i Q nh sau :

[ P]= [ P/ Q][ Q] (1.41)

P/ Q cng ln th nh hng ca Q n tn tht cng sut tc dng cng ln,

do cng nn b, nt c sp xp theo iu kin ny. S sp xp trn thc hinbng cch gn cho mi nt ba h s trng theo ba tiu chun trn. Sau ba h s

ny c t hp li cho mi nt mt h s u tin t b duy nht. Nu c nt

khng th t b do mt iu kin no th h s u tin ca nt bng 0.

Tip theo, la chn s nt b t nht v dung lng b nh nht. Nt b c

chn theo th t u tin lp, u tin chn n0nt b, dng tnh ton ch c xt


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30

n mi kh nng iu chnh ca cc ngun cng sut phn khng c v va thm

vo, cng vi iu p di ti kim tra xem in p v cc hn ch khc c b

vt khung hay khng, nu khng th dng, nu c th tng s nt b ln n1=n0+1,

ri tnh li.

Sau khi c c s nt b th dng m hnh tuyn tnh ti u ha dung

lng b cc nt b bng cch gim dn dung lng b la chn ban u. Tnh

cho mi ch ri tng hp li cho kt qu chung.

M hnh tuyn tnh c dng:

F=CIT. UG+ QL+C3T. T min (1.42)

Vi cc rng buc :Theo iu chnh in p ngun in :

UG min UG UG max (1.43)

-Theo iu chnh cng sut phn khng nt ti :

QL min QL QL max (1.44)

-Theo iu chnh in p di ti :

T min T T max (1.45)

Ngoi ra cn hn ch QG nt ngun v UL nt ti, cc hn ch ny ph thuc

vo cu trc ca li. Nu gi thit P=0, ta c h phng trnh li in :

T

U

U

J

J

J

J

J

J

Q

QL

G

LT

QT

LL

QL

LG

QG

L

G. (1.46)

Bin i ta c :

T

U

U

J

J

J

J

J

J

Q

QL

G

LT

QT

LL

QL

LG

QG

L

G.'

'

'

'

'

'(1.47)

H phng trnh ny cho php tnh c QG v UL .

C1T, C2T,C3Tl cc vc t gi c, T trong ma trn l k hiu chuyn v.


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31

*u im :

-Vic xc nh th t u tin cc nt t b kh ton din, ch tiu kinh t k thut

ng thi c quan tm.

*Nhc im :

-i vi mt mng li in gm nhiu nt, nhnh vic xt th t t b cc nt

theo cc ch tiu trn l phc tp.

-M hnh ph hp vi h thng ph ti ln, bin thin cng sut lin tc.

1.5.8 M hnh quy hoch hn hp:M hnh quy hoch hn hp gm quy hoch phi tuyn v quy hoch tuyn

tnh nguyn. M hnh ca bi ton nh sau:

Cc tiu ha hmn

i

biiii

n

i

i QkykVVZ1

0

1

)..(

Bc 1: Cho b ti mi nt ti, gii m hnh phi tuyn tm c cng sut b mi

nt.

Bc 2: Tuyn tnh ha h phng trnh ti gi tr b tnh bc 1, gii m hnh

tuyn tnh nguyn gim bt n nh nht s nt b. Trong bc ny cng phi

tnh n h s nhy cm ca ch tiu n nh in p, lch in p v tn tht

cng sut tc dng i vi s bin i cng sut phn khng nt nh m hnh trn.

Do m hnh ch quan tm n ttng vn u t nn khi gi t b cao s nh hng

ln n dung lng b, dn n hiu qu b khng cao.

- Trong iu kin thc t hin nay, khi ngi u t quan tm n li ch kinh t th

m hnh tr nn khng cn ph hp.


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32

1.6. TM HIU COS V B COS TI MT S NH MY X NGHIP:1.6.1 Cc ph ti tin hnh iu tra : tin hnh phn tch v nh gi c im tiu th cng sut phn khng v t l

tn tht in nng mng in ph ti hn hp cn tin hnh iu tra kho st thuthp cc s liu tp trung vo cc ph ti cng nghip, C th nh sau:Ti Thi Nguyn:

1. Cng ty vn dm Thi nguyn 2. Cng ty gch p lt Vit 3. Cng ty in phn km sng Cng4. Cng ty c phn thp Thi nguyn trm s II (Sng Cng) 5. Cng ty c phn thp Thi nguyn trm s I (Sng Cng) 6. Cng ty Diesel sng Cng ( L 675)7. Cng ty Diesel sng Cng ( L 673)

8. Cng ty ph tng ma s 1 sng Cng9. Cng ty xi mng Lu x10. Cng ty thp Hin Sn

Qu trnh kho st c tin hnh o trc tip hay t cng t in t. S liuthu thp c l in nng hu cng v in nng v cng trong tng thng hay cac mt khong thi gian. T tnh ton gi tr h s cng sut Cos theo cngthc sau:

22

QP

P

AA

ACos (1.48)

Trong : AP- in nng hu cng; AQ-in nn v cng.

Ti mt s a phng s liu thu c li l cng sut tc dng, in p v dng.Khi gi tr h s cng sut Cos theo cng thc sau:

IU

P

S

PCos

*(1.49)

Ti mt s im qua cng t in t ghi c ch s cng sut tc dng v

cng sut phn khng theo gi ( chnh l in nng tiu th trong tng gi). 1.6.2.Mt s nhn xt t kt qu thc t:

1.6.2.1. i vi ph ti cng nghip

- Cc ph ti cng nghip ni chung c gi tr Cos thp v u c lp t t b khng b pht Cos thp.


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33

* Cng ty xi mng Lu x, Thi nguyn c th ph ti ngy nh trn bng 2,hnh 1.7. Cng ty ny t b 600 kVar, trong c 420 kVar tp trung trm binp, cn lit ri rc cc phn xng-c nh dung lng, khng c iu chnhdung lng b ( ch c ng hay ct ton b)

Bng 2. th ph ti nh my xi mng Lu x Thi nguyn

Gi P;kW

Q ph tikVar

Q b;kVar

Q sau khib;kVar

Cos Truoc bu

Cos Sau bu

1-2 1484 1042.00 600 442 0.82 0.962-3 1344 1086.00 600 486 0.78 0.94

3-4 1319 961.00 600 361 0.81 0.964-5 1187 1018.00 600 418 0.76 0.945-6 1338 1078.00 600 478 0.78 0.946-7 1260 958.00 600 358 0.80 0.967-8 1230 1040.00 600 440 0.76 0.948-9 1147 1014.00 600 414 0.75 0.949-10 1361 1055.00 600 455 0.79 0.9510-11 1387 1080.00 600 480 0.79 0.9511-12 1337 1081.00 600 481 0.78 0.9412-13 1346 1010.00 600 410 0.80 0.9613-14 1134 1079.00 600 479 0.72 0.9214-15 1294 1007.00 600 407 0.79 0.9515-16 1321 1054.00 600 454 0.78 0.9516-17 1325 1078.00 600 478 0.78 0.9417-18 1186 1075.00 600 475 0.74 0.9318-19 1320 1248.00 600 648 0.73 0.9019-20 1135 1040.00 600 440 0.74 0.93

20-21 1092 907.00 600 307 0.77 0.9621-22 1104 920.00 600 320 0.77 0.9622-23 1106 881.00 600 281 0.78 0.9723-24 1313 1079.00 600 479 0.77 0.94


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Hnh 1.7 th Cos Cng ty xi mng Lu x Thi nguyn - ng bn di : trc khi b- ng bn trn : Sau khi b

COS TRUOC VA SAU BU

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1 3 5 7 9 11 13 15 17 19 21 23

GIO


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* Mt s ph ti khc trong khu cng nghip Thi nguyn, kt qu tnh ton ghi trn

bng 3.Bng 3. Gi tr Cos cc ph ti khu cng nghip Thi nguyn

( tnh t thng 1 n ht thng 11 nm 2007)

TT Ph ti in nng hiudng; AP;kWh

in nng vcng; AQ;kVarh

Cos

1 CT Vn dm TN 32 922 936 15 342 061 0,906

2 CT Gch p lt Vit 7 912 541 3 565 217 0,912

3 CT in phn km sng

Cng

32 182 884 14 743 344 0,909

4 CTCP Thp TN Tram I 3 178 244 1 277 213 0,928

5 CTCP Thp TN Tram II 3 077 142 1 296 620 0,922

6 CT Diesel sng Cng 6 622 560 2 801 242 0,921

7 CT Ph tng my s 1 7 040 412 2 112 536 0,958

8 CT Thp Hin Sn 5 613 1527 0,978

- Cc t b tnh c dung lng c nh, rt t ng ct mc d tiu th cng sutphn khng c thay i. Do vy khi ph ti c nhu cu cng sut phn khng nh,cng sut phn khng t t b s chy ngc v h thng, gy tn tht trong li.Nh vy t b phn tc dng.


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Ly v d : Cng ty thp Hin Sn, trm bin p s 1 ti Thi nguyn.

th ph ti ngy ghi trn bng 4, hnh 1.8

Bng 4. th ph ti ngy CT thp Hin Sn

Gi P;kW Q ph ti Cos 1-2 452.63 125.45 0.962-3 450.00 121.00 0.973-4 445.00 126.00 0.964-5 447.00 127.00 0.965-6 445.00 129.00 0.966-7 447.00 119.00 0.977-8 460.00 125.00 0.978-9 5.50 0.30 1.009-10 5.00 0.50 1.0010-11 4.60 0.40 1.0011-12 4.60 0.40 1.0012-13 4.70 0.13 1.0013-14 4.70 0.40 1.0014-15 5.50 0.30 1.0015-16 5.50 0.50 1.0016-17 5.70 0.60 1.00

17-18 5.70 0.50 1.0018-19 7.00 0.40 1.0019-20 550.00 145.00 0.9720-21 500.00 121.00 0.9721-22 450.00 126.00 0.9622-23 457.00 128.00 0.9623-24 451.00 130.00 0.96


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Hnh 1.8. h ph ti ngy Cng ty thp Hin sn TBA s 1

T bng 4, hnh 1.8 thy rng Cng ty thp Hin Sn khng b pht do Cos thp.Nhng thc t t b ch c cng dng t 20 gi m n 8 gi sng ngy hm sau,cn t 8 gi sng n 20 gi ti cng sut phn khng t t b li ngc v li, gyra tn tht trn li. Nh vy vn pht do thi cng sut phn khng t t b dtkhot phi c cp n.

-Cc cng ty c h sCos khng qu thp ( t 0,75 n 0,85) ni chung khng ct t b v s tin pht do Cos thp khng nhiu hoc so vi tng tin in lkhng ng k.

1.6.2.2. Cc c quan hnh chnh s nghip:

Cc c quan hnh chnh s nghip nh cc trng i hc, cc c quan hnhchnh,.... khng trong din b pht Cos . Thc t trong cc c quan ny ngy dngcng nhiu cc thit b in c h s cng sut Cos thp nh n Neon(Cos =0,44), cc my iu ho v cc thit b c c cu ng c (Cos ch vokhong 0,65 n 0,7),.....Do vy ti cc trm in ny khng c cng t v cng.Hn na ti y ngi ta t khi ni v tiu th cng sut phn khng v h s Cos .


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1.6.3 Tm tt v kin ngh:* Cc ph ti cng nghip nh cng ty thp, cng ty t, cng ty xi mng, cng ty

iesel, bn thn phn ln cc thit b dng in c gi tr Cos khng cao ( khong

t 0,65 n 0,75), nhng u c lp t cc b t b c nh khng b phtCos . Nhng vn y l dung lng b t kh cao ( Cos trn 0,95) m cct b li l c nh khng th iu chnh dung lng cng sut b phn khng. iu dn n khi ph ti tiu th cng sut phn khng t vo nhng gi thp im,dung lng cng sut phn khng b dng khng ht li chy ngc v li, gy tntht trn li; Khi bi ton b li b phn tc dng gy nh hng xu. Chnh vvy khi la chn dung lng cng sut phn khng b cn phi tnh ton thn trngv tt nht l s dng cc t b c th iu chnh c dung lng b theo thi iml tu thuc nhu cu tiu th cng sut phn khng ca ph ti. Mt khc nu t bkhng th t iu chnh dung lng b th phi chu pht Cos ti nhng thi im

cng sut phn khng b pht ngc v li. * Cc cng ty c h s Cos khng qu thp ( t 0,75 n 0,85) ni chung khng

c t t b v s tin pht do Cos thp khng nhiu hoc so vi tng tin in lkhng ng k. Vn y l cn xem xt li quy nh gi tr Cos ti thiu vkinh doanh (th trng) cng sut phn khng.

*i vi cc ph ti tng hp cp in t cc l ti in lc tnh bao gm cccm cng nghip nh, cn li l ph ti thp sng, sinh hot gia nh; trong cccm cng nghip u c lp t t b trnh pht Cos nn gi tr Cos ca tonl l khng thp ( u trn 0,85). Do vy bi ton v b cng sut phn khng nng

cao Cos i vi cc l ny khng thnh vn ln. Vn cn li l nn t t bpha h th 0,4kV c t ng iu chnh dung lng b cho cm ph ti hay cmdn c, trm bm l . iu ny khng c g kh khn v t b h th 0,4 kV c tng iu chnh dung lng b rt sn trn th trng m gi thnh r.

* c bit lu tm n vn Cos ti cc ph ti l c quan hnh chnh snghip :trng hc, bnh vin, c quan hnh chnh, cng s, i vi ph ti loiny theo quy nh ca ngnh in l khng b pht Cos . Trong khi gi tr Cos ca cc ph ti loi ny l rt thp. Do vy vn Cos i vi cc ph ti ny lc vn cn phi c chnh sch c th v li ch chung ca h thng in ton quc.


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CHNG II:

CHNG TRNH TNH TON B CNG SUT PHN

KHNG, C XT N CHT LNG IN NNG V

PHN TCH TI CHNH.

2.1. PHNG PHP LUN V S KHI THUT TON

2.1.1 M hnh tng qut bi ton b cng sut phn khng trong li phn

phi:

Xt li in phn phi gm n+1 nt nh s 0,1,2,,n. Cc nt u c ph ti

Pi+jQiv c th t b cng sut phn khng QBi.

Cc ngun pht ra cng sut phn khng t ti cc nt ph ti l cc t in tnh

khng iu khin v c thang cng sut ri rc. Gi s ti cc nt ca li in c

t t in tnh b cng sut phn khng, cng sut t b cc nt l QBi;

i=1..N. Khi y tn tht cng sut trn ton li s l:

i

n

i

Jj

Bjii

RU

QQP

Pi

123

2

2

10(2.1)

Ji: theo chiu cng sut tc dng, tp nhng nt j nm sau nt i ang xt.

Biu thc trn chng t rng sau khi t t in tnh b cng sut phn khng

ti cc nt ph ti th tn tht cng sut trn li in gim, chi ph cho tn tht cng

sut gim. Nhng thay vo cn u t cho xy dng trm b, gi tin mua t in

tnh, chi ph cho tn tht cng sut trn t in tnh.

Vn t ra l cn so snh gia hai chi ph: trckhi b v sau khi b tm ra

mt phng n ti u vi tng chi ph l t nht m vn m bo cc yu cu k

thut. tm c li gii ti u th trc ht phi xy dng c hm mc tiu ca

bi ton. Hm mc tiu y l hm tng chi ph tnh ton, s c trnh by trong


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phn sau. Gii bi ton b kinh t cng sut phn khng tc l i tm li gii hm

tng chi ph tnh ton l cc tiu vi cc rng buc v mt k thut.

Sau y s thnh lp m hnh bi ton b cng sut phn khng trong li i n

phn phi gm hm mc tiu v cc rng buc.

2.1.2. Hm mc tiu

Hm mc tiu l hm tng chi ph tnh ton bao gm chi ph do tn tht in

nng trn ng dy, chi ph do tn tht trong t b v chi ph lp t thit b b. C

th:

MinZZZZ 321 (2.2)

Trong :

ZTng chi ph tnh ton quy v mt nm(ng);

Z1Vn u t quy i mt nm cho thit b b;

Z2Chi ph tn tht in nng trong thit b b;

Z3Chi ph tn tht in nng trong ng dy.

- Vn u t quy i mt nm ca thit b b:

N

iiBiBtcvh QKKZ

1

01 .. (2.3)

Trong : KBi - vn u t cho mt n v cng sut thit b b ti nt i,

(ng/kVAr)

K0Chi ph c nh lp t thit b b (ng)

QBi- dung lng thit b b ti nt i, kVAr;

vh- h s chi ph vn hnh hng nm;

tc - h s khu hao;

- Chi ph tn tht in nng trong thit b b:

Bi

N

i

B QPZ1

02 ... (2.4)


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41

Trong :

p0 tn hao cng sut tc dng cho mt n v dung lng

b,kW/kVAr;

B - thi gian tn tht cng sut cc i ca thit b b, gi/nm; (c

th ly bng thi gian lm vic ca thit b b)

- gi thnh in nng, /kWh.

- Chi ph tn tht in nng trn ng dy:

N

i

nhii QRU

Z1

2

233..

.10.3

.(2.5)

Trong :

- thi gian tn tht cng sut cc i ca li, gi/nm;

( cn lu l B )

Ri - in tr ca dy dn nhnh i, ;

U - in p nh mc ca li, kV;

Qnhi- cng sut phn khng ti trn nhnh i khi c b cng sut phn

khng ti cc nt.Cng sut phn khng ti cc nhnh khi xt n c cc cng sut b ti cc nt

c tnh tng t nh tnh dng cc nhnh, c th l :

B

nh QQAQ . (2.6)

Trong : Qnh - ma trn ct cng sut phn khng truyn trn nhnh;

A = Z . C - ma trn h s, ma trn vung NxN;

Q - QB - ma trn ct hiu cng sut phn khng ph ti v cngsut b.

Hay vit di dng i s:

N

j

Bjjijnhi QQAQ1

. (2.7)


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42

Trong :

Qjnh - cng sut phn khng truyn ti trn nhnh j;

Aij - phn t ca ma trn A (Nu nt i khng ni vi nt j th

Aij = 0);

Qj - cng sut phn khng ph ti ti nt j;

QBi - cng sut b ti nt i.

Ghi ch: trong Z3nu tnh y phi c thnh phn tn tht cng sut do cng

sut tc dng P gy ra, nhng bi ton xt Min hm chi ph tnh ton b phn tn

tht ny i vn khng nh hng g v chng l hng s khng ph thuc vo Q B.

T(2.3), (2.4) v (2.5) ta thy cc tr s Z 1, Z2, Z3u ph thuc vo tr s QBi.Nh vy yu cu ca bi ton l xc nh cc gi tr cng sut phn khng thit b b

(QBi) t ti cc nt ca li in sao cho tng chi ph tnh ton Z l nh nht.

2.1.3 Cc rng buc

- Tng cng sut b ti cc nt khng vt qu gi tr b tng ton li:

B

N

i

Bi QQ1

(2.8)

- Cng sut b ti mt nt khng vt khi phm vi cho php:

NiQQQMax

BiBi

Min

Bi 1; (2.9)

- B sao cho h s cng sut Cos ti cc nt pha cao p nm trong phm vi

cho php:

niCosCosCos MaxiMin 1; (2.10)

Trong :22

Biii

ii

QQP

PCos (2.11)

Sau y xt mt s phng php gii bi ton b hin c.


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2.1.4 M hnh bi ton b cng sut phn khng khi c xt n my bin p:

Trong phn trn cp n m hnh bi ton b i vi li phn phi hnh

tia, mt cp in p v cha xt n my bin p. Tuy nhin, tn tht trong my bin

p cng rt ng k. Do , nu b qua my bin p th li gii bi ton s thiu

chnh xc. Sau y s trnh by m hnh bi ton b khi c xt n my bin p.

Xt li in phn phi gm n+1 nt nh s 0,1,2,,N v M nt c my bin

p nh s N+1,N+2,,N = N+M. Cc nt u c ph ti P i+jQiv c th t b

cng sut phn khng QBi.

Nt MBA tng qut c c ph ti pha cao (gp c tn tht khng ti), ph ti

pha h v c hai cp in p u c th t b cng sut phn khng. Ni tm li,ti nt c my MBA s c xem l hai nt ph ti (c trng cho ph ti pha cao

v h ca MBA), m nhnh ni gia hai nt c tng tr bng (RMBA + jXMBA). Trong

RMBA v XMBAtheo th t l in tr v in khng ca my bin p.

2.1.5 Mt s gi thit khi tnh ton ti u cng sut b: M hnh bi ton b ti u cng sut phn khng bng t in trn li phn

phi l mt bi ton phc tp c nhiu yu t tc ng v vy n gin ha bi

ton cn mt s gi thit nh sau:

-Gi tr in p li c coi l khng i.

QBC

PC+jQC

QBHPH+jQH

QBC

PC+jQC

QBHPH+jQH

RMBA+jXMBAMBA

Hnh 2.1- M hnh nt c my bi n p


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-Tnh cht ca ti coi l nh nhau ti cc nt (gi tr = const).

-Gi tr ca thit b b c coi nh l t l thun vi cng sut ca chng v khng

xt n cc nh hng khi c s thay i v gi (khng ph thuc vo cc yu t

kinh t x hi).

-Gi tr cos l gi tr trung bnh khng i.

-Vi li phn phi c nhiu trc chnh, vic thay i cng sut phn khng ti mt

nt bt k trn trc chnh nh hng khng ng k n vic thay i cng sut phn

khng ti cc nt khc trn trc chnh.

2.2 Phng php gii bi ton b cng sut phn khng

2.2.1 Tng quan

Hin nay c rt nhiu cch gii khc nhau gii bi ton b ti u cng sut

phn khng trong li in.

- Phng php tng ng lin tip, cho php gii bi ton b cng sut phn

khng trong li in rt n gin v thun tin m khng cn phi lp h phng

trnh;

- Phng php ma trn, y a vo ma trn in tr nt tnh ton in

nng trong li in. Phng php ny tnh ton b cng sut phn khng trn c s

cc biu thc ma trn tng minh lm gim kh nhiu khi ln g tnh ton. Pht

trin ca phng php ny ngi ta xy dng ma trn Tp, thit lp cc cng thc

tnh nh thc v phn ph i s ca ma trn in tr nt ca li in. S dng cc

phng php phn tch Tp xy dng cng thc tnh ma trn in trnt. Bng

phng php i s ma trn xy dng cc thut ton gii bi ton b;

- Phng php gii bi ton b ti u cng sut phn khng trong li in knda trn phng php quy hoch ton hc, chuyn bi ton phn b ti u cng sut

phn khng vbi ton quy hoch ton phng. Thut ton ny cng ch tin hnh

trong iu kin thang cng sut TT lin tc;

- Phng php quy hoch ng gii bi ton b c tnh n tnh ri rc ca

thang cng sut TT. Trn c s tin hnh qu trnh thun v ngc ca phng


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php quy hoch ng. Trong qu trnh thun tin hnh hp nht cc nhnh tm

quan h Z n (QB n) v QBn (QB n). Trong Z n, QBn, QB ntng ng l tng chi ph

tnh ton bc hp nht th n, cng sut TT t u cui th n, tng cng sut

TT t u cui cc nhnh trong bc hp nht th n. T quan h Q Bn(QB n) tm

c trong qu trnh thun tin hnh qu trnh ngc ca thut ton tm cc gi tr

cng sut TT t ti cc nt ca li in tng ng vi cc tiu hm tng chi ph

tnh ton;

- Ngoi ra cn rt nhiu phng php khc nh phng php t hp cc qu

trnh gin on, phng php din tch, phng php lp, phng php nh gi cht

lng in p, Cng cp n cch gii bi ton b ti u cng sut phn khngtrong nhng rng buc v hm mc tiu khc nhau.

Nh vy, hin nay c rt nhiu phng php khc nhau nghin cu v bi

ton b cng sut phn khng. iu cho thy b cng sut phn khng l mt vn

cp thit v vn hnh li in. Nhng kt qu nghin cu trong lnh vc ny rt

phong ph v a dng.

Tuy nhin, hng lot nhng kh khn trong gii quyt vn ny khi tnh ton

li in thc t vn cha c gii quyt trit (nh kh khn v khi lng tnh

ton, nh, hnh thc ho,...)

Sau y gii thiu thut ton quy hoch ng gii bi ton b cng sut phn

khng.

2.2.2. Thut ton gii bi ton b cng sut phn khng bng phng php

quy hoch ng:

Gii bi ton xc nh cng sut v ch t TT trn c s thut ton quy hochng bao gm 2 qu trnh thun v ngc.

Trong qu trnh thun thc hin cc bc hp nht cc nhnh bt u t ph ti

v ti ngun cung cp tm gi tr nh nht ca hm mc tiu.

Gi s lng cng sut TT cn t l BQ . Chia BQ ra lm m mc:


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0-BQ ; BQ - 2 BQ ... m BQ - BQ . Bc chia ny cng nh chnh xc

cng cao. Nhng do thang cng sut TT c sn xut theo tiu chun nn ta chn

sao cho mc trn ca mi bc l bi s ca thang cng sut TT.

* i vi li in ng dy chnh (hnh 2 -2a) trnh t bt u t ph ti cui

li in (nhnh 1).

0 n 2 1 0Hnh 2.2a

Hnh 2.2b

0

Hnh 2.2c

Hnh 2.2: Cc loi s li phn phi

Bc 1: Tnh gi tr hm )(11 B

Qf vi tt c cc gi tr c th ca1B

Q (nhnh 1 hnh

2.2a). Quan h ny c k hiu l )( 11 BQZ ; ngha l:

)( 11 BQZ = )( 11 BQf (2.12)

Bc 2: thc hin hp nht nhnh 1 vi nhnh 2 (hnh 2.2a). i vi mi mc k ca

BQ cn tm t hp ti u ca 1BQ v 2BQ tho mn iukin:

);()(min 22112 BBB QQfQfZ (2.13)

Thay )( 11 BQf ta c:

);()(min)( 2221122 BBBB QQfQZQZ


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Bc i: bc th i, i vi mc k caBQ , tm t hp ti u ca BiQ v tng

11...21 ii BBBB QQQQ

Phng trnh trung ton c dng:);()(min)( 1

0iBBiiBiiBi

QQiBi QQfQQZQZ

iBBi

(2.14)

Bc n: Sau khi thc hin (n - 1) bc hp nht, tin hnh hp nht nhnh th n.

bc ny tm c hm quan h gia tng chi ph tnh ton ca ton li in vi

tng cng sut TT t ti cc nt trong li. Phng trnh truy ton bc n c

dng:

);()(min)( 10

nBBnnBnnBnQQ

nBn QQfQQZQZnBBn

(2.15)

* i vi li in hnh tia (hnh 2.2b) vi cc nhnh ch c mt u nhnh

chung vi u cc nhnh khc trong li, trc khi thc hin cc bc hp nht phi

tin hnh tnh gi tr ca hm chi ph tnh ton vi tt c cc gi tr c th c ca

cng sut TT t u cui mi nhnh. Sau thc hin qu trnh hp nht

nhnh.

Trng hp ny phng trnh trung ton cho bc hp nht th i c dng:

)()(min)(1

0BiiBiiBi

QQiBi QfQQZQZ

iBBi

(2.16)

* i vi li phn phi h (hnh 2.2c) bao gm m ng dy chnh, dc mi

ng dy chnh c n nt, n nhnh ni tip nhau. Nh vy ng dy chnh c th

coi nh mt li in ng dy chnh. Thut ton gii i vi li in phn phi

(hnh 2.2c) l qu trnh hp nht nhnh bt u t cui mi ng dy chnh thc

hin theo thut ton i vi li in. Sau khi cc nhnh ca mi ng dy chnh

c hp nht thnh mt nhnh tng ng, li in mi c dng hnh tia.

C th thy rng i vi li in phn phi h thut ton gii l tp hp ca hai

thut ton gii i vi li in ng dy chnh v li in hnh tia nh trnh

by.


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Trong qu trnh ngc s xc nh chnh xc cng sut TT cn t ti cc nt

hm chi ph ti cc li l nh nht. Sau khi thc hin bc hp nht cui cng ta

tm c hm quan h gia tng chi ph tnh ton ca ton li in i vi tng

cng sut TT t ti cc nt trong li in, s xc nh c tng cng sut TT

t ti cc nt trong ton li l bao nhiu l ti u. T cn c vo cc quan h

)( iBi QZ xy dng trong qu trnh thun xc nh gi tr cng sut TT

cn t ti cc nt trong li.

2.2.3 Xt n rng buc v in p:

Cng vi qu trnh thun ca quy hoch ng s ng thi tnh n tn

tht in p trn cc nhnh ng vi gi tr cng sut chy trn nhnh . Ti mi

bc ca qu trnh quy hoch ng, ng vi tng cng sut b ca cc nt i l QBjis

ghi li cng sut b cc nt ng vi hm chi ph nh nht v ghi li tn tht in

p U cc i t nt i ti nt ta kim tra tn tht in p. Ngoi ra cn ghi li cc

phng n khc, tc l cc t hp khc mc d chi ph ln hn nhng tn tht in

p cc i t nt i ti cc nt cn kim tra li nh hn t hp c hm chi ph nh

nht.Khi hp nht hai nhnh thng i v i th tng tn tht inp l ( Ui+ Ui). Khi hp

nht hai nhnh hnh tia th tn tht in p s l gi tr max ( Ui; Ui).

Sau khi thc hin bc quy hoch cui cng xc nh c quan h Znopt(QB ; Ui)

s c li gii l hm chi ph thc s nh nht sao cho m bo iu kin v tn

tht in p.

2.2.4. Hnh thc ho thut ton v s khi.

Khi thc hin gii bi ton b cng sut phn khng bng phng php quy

hoch ng thc hin trn my tnh in t c mt s vn t ra l lm th no

hnh thc ho c qu trnh hp nht, cn phi lm th no my hp nht cc

nhnh ng th t.


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o Nh trnh by, qu trnh thun c thc hin bng cch hp nht cc

nhnh theo trnh t nht nh (t cc nhnh ct n cc nhnh u).

m hnh ha thnh s khi thut ton, trc ht ta nh ngha mt s nhn

sau:

o Nutcon[A]: l nt ni vi nt A nhng ng sau A tnh theo chiu dng cng

sut tc dng chy trn ng dy.

o Nutcha[A]: l nt ni vi nt A nhng ng trc A tnh theo chiu dng

cng sut tc dng chy trn ng dy.

o Anhem[A]: l nt c cng Nutcha vi nt A. V d: B = Anhem[A] th

Nutcha[B] = Nutcha[A]. Ni cch khc, B v A c cng Nutcha.a. S khi thut ton qu trnh thun: (Tnh hm chi ph tnh ton tng

ng vi tt c cc phng n b ti cc nt).

Stop = 0B = nut[0]

Stop = 1

Stop = 1

B c nt con

0

0

1

1

B = Nutcon[B]

B = nut[0]

Tnh b ti B

B c anh em

B =Anhem[B]

B = Nutcha[B]

1

STOP

0

Hnh 2.3: S khi thut ton qu trnh thun

BEGIN

10


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b. S khi qu trnh ngc: tm cng sut v v tr t b ti u (hm chi

ph tnh ton t cc tiu)

2.2.6 Cc s liu cn a vo tnh ton:

Vic gii bi ton b vi khi lng tnh ton ln thc hin nhiu vng lp do

phi thc hin trn my tnh.

tnh ton cn nhp vo cc thng s:

* in p nh mc ca li phn phi (KV).

* M hiu dy ni gia hai nt, chiu di dy dn (km).

* Thng s nt:

- Cng sut max Pmax(KW), Q(KVAr).

-in tr v in khng ca my bin p tng ng.

Stop = 0B = nut[0]

Stop = 1

Stop = 1

B c nt con

0

0

1

1

B = Nutcon[B]

B = nut[0]

B c anh em

B =

Anhem[B]

B = Nutcha[B]

1

0

Hnh 2.4: S khi thut ton qu trnh ngc

10

Tm Qb[B]

HIN TH KTQU


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2.2.7 V d p dng :

Xt li in n gin nh hnh sau:

Hnh 2.5 S liin

Khi thc hin gii bi ton b bng phng php quy hoch ng, qu trnh thun

thc hin hp nht cc nhnh theo th t (t cc nhnh ct cho n nhnh u). Vi

v d ny s hp nht nh sau:

Bc 1 Hp nht nhnh 5 v 6.

Bc 2 hp nht 5-6 v 4.

Bc 3 Hp nht 2 v 3.

Bc 4 Hp nht nhnh 2-3 vi 4.

Bc 5 Hp nht nhnh 4 -2 vo 1.

Dng phng php quy hoch ng xc nh v tr v cng sut t b ti cc nt

ca li in ny, cho cc gi tr:

0

1 4

6

5

2 3


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vh=0,1; tc=0,125; Un=10KV; Kb0=2.106ng. Kb=150.10

3/kVAr;

T=4500h; =3000h;C =750/kWh; Pb=0.0023kW/kVAr.

S liu ph ti v ng dy cho trong bng sau:

Nt Ppt(KW) Q(KVAr) Qbmax(KVAr)

1 1000 1000 1000

2 600 600 600

3 500 500 500

4 400 400 400

5 300 300 300S liu ng dy:

TT Nt

u

Nt

Cui

Loi dy L(km) S

l

R0

( /km)

X0

( /km)

Icp(A)

1 0 1 AC-120 1 1 0.27 0.391 380

2 1 2 AC-70 1.2 1 0.46 0.408 2653 2 3 AC-50 1.5 1 0.656 0.418 210

4 1 4 AC-95 1 1 0.33 0.397 330

5 4 5 AC-50 1.2 1 0.656 0.418 210

6 4 6 AC-50 2 1 0.656 0.418 210

Kt qu tnh ton:

Kt qu tnh ch xc lp:

--------------------------------------

Tng cng sut yu cu u ngun: 3400.563 +j3423.566 kVA

Tng cng sut ph ti: 3300.000 +j3300.000 kVA

Tng tn tht cng sut : 100.563 +j123.566 kVA


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in p thanh ci tng: Udm = 10.00/_0 kV

Nt c in p thp nht: Umin = 9.555 /_-0.001(kV)

Tn tht in p cc i: deltaUmax = 4.4%

Kt qu tnh ton b:QB = 1630 KVAr. Li nhun thu c 45000000 ng/ nm.

2.3. Chng trnh my tnh v s dng chng trnh

2.3.1.Kin trc chng trnh:

Chng trnh c vit bi ngn ng lp trnh Dephi 7.0 c th chy tt trn mi

trng Window XP. Giao din s dng thn thin vi ngi dng.


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54

Menu chnh

D liu

Load Flow

B CSPK

To mi

__ M__ Lu__ Lu vi tn khc__ Nhp d liu

__ th ph ti__ Bn a l

__ Xut d liu__ Nt__ Nhnh__ My bin p

__ In n

__ Kt thc

Tnh ton

__ Thay i thng s__ Nt__ Nhnh__ Bin p 2 cun dy

__ Bin p 3 cun dy__ T__ Khng

Tnh ton

__ Thay i thng s__ Ccc h s__ Cc rng buc

TR GIP Hng dn s dng__ Gii thiu PSA

Hnh 2.6:Ki n trc chng trnh PSA


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2.3.2 S khi ch-ng trnh:

TNH TON

M file c sn

M phngli mi

To file mi

Thay i s cutrc li

Vo sliu mi

Thay is liu c

Tnh

Loadflow

Tnh B kinh tcng sut phnkhn

GHI VOFILE

M PHNG

VO S LIU

- S liu bi ton LF - S liu bi ton b- th ph ti

- th cos

XUT D LIU

- Bng- File- ha

- My in

FILE

Hnh 2.7: S khi tng qut chng trnh PSA


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2.3.3 Giao din chng trnh:

Hnh 3.14: Giao din chnh chng trnh PSA

2.3.4 Vo S liu : Vo s liu thng s ng dy

Cng c mphng li in

Hin th ktqu Load Flow

Cc modulTnh ton

Ca s chnhcachng trnh

Ca s m phng,hin th s li in


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Vo s liu nt:


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58

CHNG III. TNH TON P DNG:

kim chng cho phng php b ti u cng sut phn khng a ra chng III xt mt li in thuc khu vc Huyn ng H tnh Thi Nguyn tnh ton p dng.3.1 S l 677:


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3.2 Cc S liu Tnh ton:

Bng 3.1 S liu My Bin p trn l 677;

Stt Tn TBA Sm(KVA)Um1/Um2 (KV)

I0%

P 0%

PN(W)

U N(V)

Rn( ) Xn(

1 ng bm 2 180 6/0,4 1.03 500 2323 4.47 0.86 5.10

2 ng bm 3 250 6/0,4 3.83 1240 4850 3.53 0.93 2.79

3Cha hang4 320 6/0,4 3.83 900 4200 3.83 0.49 2.44

4 Lng ng180 6/0,4

3 850 2825 4 1.05 4.50

5 ng bm 1 250 6/0,4 3.68 960 3700 6.5 0.71 5.36

6 Gia By180 6/0,4

1.03 500 2323 4.47 0.86 5.10

7 Cha hang5 250 6/0,4 2.5 900 3650 3.8 0.70 3.08

8 Tm Lp 400 6/0,4 2.3 1080 5500 4.5 0.41 2.30

9 UB Huyn 180 6/0.4 1.6 620 2603 5.7 0.96 6.52

10Nc ngBm

75 6/0.4 1.67 300 1161 3.892.48 10.5

11Bu in 50 6/0.4

2.17 260 1073 4.07 5.15 16.14

12 x 250 6/0.4 3.68 960 3700 6.5 0.71 5.36


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60

Bng 3.2 S liu ng dy ca l 677:

Nt u NtCui LoiDy L(Km) S l R( ) X( ) Icp (A)

0 1 AC70 0.686 1 0.46 0.408 265

1 2 AC50 0.64 1 0.65 0.418 210

2 3 AC50 0.035 1 0.65 0.418 210

2 4 AC50 0.15 1 0.65 0.418 210

1 5 AC70 0.58 1 0.46 0.408 265

5 6 AC50 0.04 1 0.65 0.418 2105 7 AC70 0.116 1 0.46 0.408 265

7 8 AC50 0.45 1 0.65 0.418 210

8 9 AC50 0.08 1 0.65 0.418 210

8 10 AC50 0.24 1 0.65 0.418 210

8 11 AC50 0.025 1 0.65 0.418 210

7 12 AC70 0.14 1 0.46 0.408 265

12 13 AC50 0.055 1 0.65 0.418 21012 14 AC70 0.095 1 0.46 0.408 265

14 15 AC50 0.64 1 0.65 0.418 210

14 16 AC70 0.408 1 0.46 0.408 265

16 17 AC50 0.02 1 0.65 0.418 210

16 18 AC70 0.302 1 0.46 0.408 265

18 19 AC50 0.64 1 0.65 0.418 210

18 20 AC70 0.52 1 0.46 0.408 265

20 21 AC50 0.108 1 0.65 0.418 210

20 22 AC70 0.24 1 0.46 0.408 265


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61

Bng 3.3 S liu ph ti cc i trn l 677:

TT Tn nt Loi nt Pt(KW) Qt(KWAr)

1 677 0 0

2 ng Bm 1 PQ 211 134

3 ng Bm 2 PQ 146 105

4 ng Bm3 PQ 218 123

5 Cha Hang 4 PQ 273 167

6 Cha Hang 5 PQ 207 1397 Tm lp PQ 326 231

8 UB Huyn PQ 139 114

9 x PQ 207 140

10 Bu in PQ 41 29

11 Gia By PQ 146 106

12 Lng ng PQ 151 98

13 Nc ng Bm PQ 57 49

Qa trnh tnh ton thc hin bng chng trnh:

Vi cc s liu s dng :

vh=0,1; tc=0,125; Un=10KV; Kb0=2.106ng. Kb=150.10

3/kVAr;

T=4500h; =3000h;C =750/kWh; Pb=0.0023kW/kVAr.

3.3 Kt qu tnh ton ng vi ch ph ti cc i:

3.3.1 Kt qu trc khi b ti u:






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62

Nt c in p thp nht: Umin = 5.260 /_-2.663(kV)


Bng 3.4Tn tht in p trn l 677 khi cha b :

TT Tn nt U nt U(nt)% Pmax(KW) Q(max) Cos1 1 5.802 3.3 0 02 2 5.775 3.7 0 03 3 5.774 3.8 0 04 Cha Hang 5 5.672 5.5 207 139 0.83025 4 5.775 3.7 0 06 Bu in 5.653 5.8 41 29 0.81647 5 5.653 5.8 0 08 7 5.625 6.3 0 09 8 5.563 7.3 0 010 9 5.556 7.4 0 011 x 5.386 10.2 207 140 0.828312 11 5.553 7.5 0 013 Tm lp 5.429 9.5 326 231 0.815914 10 5.552 7.5 0 015 Cha Hang 4 5.452 9.1 273 167 0.8531

16 12 5.607 6.6 0 017 13 5.606 6.6 0 018 UB huyn 5.443 9.3 138.6 114 0.772319 14 5.505 8.3 0 020 16 5.473 8.8 0 021 18 5.452 9.1 0 022 20 5.431 9.5 0 023 21 5.428 9.5 0 0

24 Lng ng 5.314 11.4 151 98 0.838825 22 5.426 9.6 0 026 Gia By 5.299 11.7 146 106 0.809227 19 5.428 9.5 0 028 ng Bm 1 5.26 12.3 210 134 0.84329 17 5.473 8.8 0 030 bm B 5.351 10.8 57 48 0.7649


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63

31 15 5.482 8.6 0 032 ng Bm 3 5.38 10.3 218 123 0.870933 6 5.652 5.8 0 0

34 ng Bm 2 5.531 7.8 146 105 0.8119

3.3.2 Kt qu tnh b cng sut phn khng:

Bng 3.5 Gi tr Q b ti cc nt

TT Tn nt Qb Cos( ) trc b Cos( ) sau b

1 ng Bm 1 130 0.843 1

2 ng Bm3 110 0.871 0.998

3 Cha Hang 4 150 0.853 0.998

4 Cha Hang 5 70 0.813 0.949

5 Tm lp 210 0.816 0.998

6 UB Huyn 90 0.772 0.985

7 x 120 0.828 0.995

8 Gia By 100 0.809 0.999

9 Lng ng 90 0.839 0.99910 Nc ng Bm 40 0.765 0.99

Tng dung lng b l: 1110 KVAr.


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64

Bng 3.6 Tn thtin p trc v sau khi b

TT Tn nt Trc khi b Sau Khi BU nt U(nt)% U nt U(nt)%

1 1 5.802 3.3 5.861 2.322 2 5.775 3.7 5.838 2.703 3 5.774 3.8 5.837 2.724 Cha Hang 5 5.672 5.5 5.775 3.755 4 5.775 3.7 5.838 2.706 Bu in 5.653 5.8 5.717 4.727 5 5.653 5.8 5.76 4.008 7 5.625 6.3 5.742 4.30

9 8 5.563 7.3 5.698 5.0310 9 5.556 7.4 5.693 5.1211 x 5.386 10.2 5.644 5.9312 11 5.553 7.5 5.691 5.1513 Tm lp 5.429 9.5 5.657 5.7214 10 5.552 7.5 5.69 5.1715 Cha Hang 4 5.452 9.1 5.658 5.7016 12 5.607 6.6 5.73 4.5017

13 5.606 6.6 5.73 4.5018 UB huyn 5.443 9.3 5.676 5.4019 14 5.505 8.3 5.665 5.5820 16 5.473 8.8 5.645 5.9221 18 5.452 9.1 5.631 6.1522 20 5.431 9.5 5.618 6.3723 21 5.428 9.5 5.616 6.4024 Lng ng 5.314 11.4 5.58 7.0025 22 5.426 9.6 5.615 6.42

26 Gia By 5.299 11.7 5.586 6.9027 19 5.428 9.5 5.615 6.4228 ng Bm 1 5.26 12.3 5.581 6.9829 17 5.473 8.8 5.645 5.9230 bm B 5.351 10.8 5.6 6.6731 15 5.482 8.6 5.648 5.87


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65

32 ng Bm 3 5.38 10.3 5.604 6.6033 6 5.652 5.8 5.759 4.0234 ng Bm 2 5.531 7.8 5.641 5.98

Kt qu tnh ch xc lp sau khi b:

--------------------------------------





Nt c in p thp nht:Umin = 5.580 /_-3.724(kV)


3.3.3 Hiu qu sau khi b:

Kt qu tnh ton thy c:

+ Tn tht in p gim ng k: tn tht in p cc i gim 5%.

+ Tn tht cng sut gim:

Tng tn tht cng sut trc khi b: 177.050 +j223.791 kVA Tng tntht cng sut sau khi b : 114.394 +j145.614 kVA

+Cng huy ng u ngun gim: (ch yu cng sut phn khng)

Tng cng sut yu cu u ngun trc khi b:2296.910 +j1657.791 kVA

Tng cng sut yu cu u ngun sau khi b: 2234.254 +j470.614 kVA

+ Tng li nhun thu c l: 66.366.000 ng/ nm.

3.4 Phn tch kinh t ti chnh v nh gi hiu qu kinh t b cng sut phn

khng.3.4.1 Cc chi ph v li ch khi t b:

lp t c cu b cn phi c mt lng chi ph vn u t mua sm v

xy dng. Doanh thu ca d n bao gm li ch do gim tn tht, li ch do nng cao

cht lng in.

3.4.1. Dng thu


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66

Tng thu trong mt nm ca d n l gi tr sn phm tnh bng tin ca d

n, c xc nh bng tng s tin li nhun trong nm ca d n

Tng doanh thu tng thm nm th t

B t=B t+Bclt (3.1)B t- Gim chi ph tn tht nm th t so vi nm gc

t

mttt

A

gAAAB1)( 0 (3.2)

A0, At- tn tht in nng tng i trc v sau khi t b;

At- tng in nng truyn ti qua li tnh ton, kWh;

gm- gi mua in nng, /kWh;

Bcl- Hiu qu tng thm do cht lng in tt hn Bcl=Acl.t.gcl (3.3)

Acl.tin nng cht lng tng thm do t c cu b:

Acl.t=(pcl.t-pcl0)At

pcl.t, pcl0xc xut cht lng in nng nm th t v nm trc khi t b;

pclxc sut cht lng innng;

gcl- gi thnh in nng cht lng /kWh.

3.4.2. Dng chi ca d n

Dng chi ca d n c tnh bng cc chi ph do mua sm xy dng, vn

hnh v tr li do vay vn

Tng chi ph nm th t:

C t= Kt + CO&M + Ctra lai (3.4)

Kt - Tng chi ph cho vic mua sm, lp t thit b b nm th t;

CO&Mt- Chi ph bo dng v vn hnh nm th t

CO&Mt=kO&MKt (3.5)

kO&Mh s vn hnh v bo dng li in; Ctra laichi ph tr li vn vay ngn hng

Ctra lai = Vvayllai

Vvay- vn vay ngn hng;

llaili sut ngn hng.


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67

3.4.3. Dng tin ca d n

Dng tin ca d n l hiu gia tt c cc khon doanh thu v tt c cc chi

ph cn thit cho mt d n. Thng th dng tin khng th xc nh trc c m

phi d bo, v vy i hi nh ut phi c s phn tch, tnh ton mt cch khoahc trn c s cc d liu tin cy ban u. Gi tr dng li nm th t c xc nh

theo biu thc

Lt= B t - C t (3.6)

Trong :

B tdng thu;

C tdng chi.

Do gi tr tin t c gi tr thay i theo thi gian, c th nh gi chnhxc gi tr ca dng tin, ngi ta phi qui i cc gi tr ca ng tin cc thiim v thi im hin ti t0=0 theo h s quy i .

t

tt

tqd L

i

LL

)1( (3.7)

Trong :

- tha s quy ii1

1

i -H s chit khu3.4.2. Cc ch tiu c bn ca d n

1). Gi tr li sut thun quy v hin ti

Nh bit, li sut l hiu gia doanh thu v chi ph. Nhng phng n c

doanh thu ln hn chi ph l nhng phng n mang li hiu qu kinh t. Gi tr tng

li sut trong sut i sng d n quy v thi im hin ti k hiu l NPV (Net

Present Value) s l mt trong nhng ch tiu c bn nh gi cc d n.

NPV =n

t

t

tt iCB0

)1)(( =n

t

t

t iL0

)1( ; (3.8)

2). T s gia doanh thu v chi ph

C th da vo hiu qu ca mt ng vn chi ph cho d n m c biu th bi t

s


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68

R =C

B= n

t

t

t

n

t

t

t

iC

iB

0

0

)1(

)1(

; (3.9)

3) H s hon vn ni ti k hiu l IRR (Internal Rate of Return) l h s chit

khu ng vi gi tr tng li sut hin ti NPV = 0 .

NPV =n

t

t

tt IRRCB0

)1)(( = 0; (3.10)

Phng trnh ny c th gii theo phng php gn ng

IRR = i1 + (i2 - i1)21

1

NPVNPV

NPV; (3.11)

i1, i2- cc gi tr chit khu gn nhau nht m gi tr NPV bt u i du.

NPV1 , NPV2 - cc gi tr tng li sut ng vi i1 v i1.

4). Thi gian hon vn T

Thi gian hon vn l thi gian m tng doanh thu bng tng chi ph, hay ni

cch khc l thi gian m tng li sut b p c chi ph ca d n.

NPV =T

t

t

tt iCB0

)1)(( = 0 ; (3.12)

Phng trnh trn c th gii gn ng.

T = tn+21

1

NPVNPV

NPV; (3.13)

tn - s nm trn ngay trc khi t c gi tr NPV=0;

NPV1, NPV2 - cc gi tr ng vi thi gian tnv nm sau , tc l nm tn+1.

Kt qu tnh ton phn tch kinh tti chnh d n b cng sut phn khng i

vi mng in 677. Cc ch tiu hiu qu b cng sut phn khng mng in 677:

NPV=139,112 triu VN;

IRR=20%;T = 3,59 nm; B/C=2,945.


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69

CHNG IV:

TH TRNG IN NNG PHN KHNG:

4.1 Th trng in nng phn khng vit nam:4.1.1 Phn tch m hnh kinh doanh in nng phn khng hin ti Vit Nam:

Hin ti nc ta vic kinh doanh in nng phn khng c thc hin trn

c s pht h s cos thp. Thc hin theo thng t lin tch ca b cng nghip .

Nhm m bo cho s dng in tin cy, hiu qu v an ton.

4.1.1.1 Cch xc nh h s cng sut trung bnh:

a) H s cng sut trung bnh c xc nh nh sau:

22)cos(

qp

p

AA

A hoc )cos(cos

Ap

Aqartg (4.1)

Trong : Ap: in nng tc dng trong mt chu k ghi ch s cng t (kWWh).

Aq: in nng phn khng trong mt chu k ghi ch s cng t tng ng (kWArh).

b) Trng hp bn mua in k mt hp ng kinh t cho nhiu cng t ti mt a

im c cp chung cng mt ng dy trung th, cao th th h s cng sut

trung bnh c xc nh bng cch cng sn lng in nng tc dng v in nng

phn khng ca cng t tnh cos trung bnh.

c) Trng hp bn mua in c s dng in ngoi mc ch sn xut, kinh doanh,

dch v th vic xc nh h s cng sut nh sau:

-Khi c cng t o m phn in nng s dng sn xut, kinh doanh, dch v th

ch p dng mua cng sut phn khng i vi phn in nng s dng cho mc

ch ny.

-Khi khng tch ring c phn in nng s dng sn xut, kinh doanh, dch v

m ch c cng t o m in nng chung, nu h s cng sut cos


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70

4.1.2 Phng php xc nhtin mua cng sut phn khng:

Tin mua cng sut phn khng (cha bao gm thu GTGT) c tnh theo

cng thc: Tq = Ta x k % (4.2)

Trong : -Tq: Tin mua cng sut phn khng(cha c thu GTGT)

-Ta: Tin mua in nngtc dng (cha c thu GTGT)

- k: H s b p chi ph do bn mua in s dng qu lng cng sut

phn khng quy nh (%)

H s k c tnh theo bng sau :

Bng 4.1

TT H s cng sut(cos )

k (%) STT H s cng sut(cos )

k (%)

1 0,85 0 15 0,71 19,72

2 0,84 1,19 16 0,70 21,43

3 0,83 2,41 17 0,69 23,19

4 0,82 3,66 18 0,68 25,00

5 0,81 4,94 19 0,67 26,87

6 0,80 6,25 20 0,66 28,79

7 0,79 7,59 21 0,65 30,77

8 0,78 8,97 22 0,64 32,81

9 0,77 10,39 23 0,63 34,92

10 0,76 11,84 24 0,62 37,10

11 0,75 13,33 25 0,61 39,34

12 0,74 14,86 26 0,60 41,67

13 0,73 16,44 27 Di 0,60 44,07

14 0,72 18,06


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71

Mt s nhn xt:

Phng php tnh ton dung lng chi tr cho in nng phn khng cha thc s

hp l do:

-Trn c s no nh ra mc cos ti thiu phi np tin pht cos l 0,85.

- Cn c vo u xc nh mi quan h gia gi tr ca h s b k v h s cos .

Nh vy c th thy l phng php kinh doanh in nng phn khng hin ti cha

da trn c s phn tch kinh t k thut hp l. iu dn ti vic mt cng bng

gia cc nh kinh doanh in v khch hng, v gia cc khch hnh vi nhau.

Phng php kinh doanh ny ch n thun p t khch hng phi mua in nng

phn khng m khng khuyn khch h tham gia vo qu trnh iu tit ci thin ch lm vic ca h thng in.

4.2 Cc m hnh kinh doanh in nng c th c p dng:

4.2.1 Phng n I: Vn p dng phng php kinh doanh cng sut phn khng

nh hin nay nhng thay i gi tr cc h s cos v t l tin pht cho hp l:

Xc nh h s cos ti thiu:

H s cos ti thiu c xc nh ph thuc vo ch s dng in ca cc

doanh nghip, c th l ph thuc vo h s in kn th ph ti (Kk) v h s

tham gia vo ph ti cci ca h thng (KtM). Gi tr ca h s cos ti thiu c

th xc nh theo :

cos kt=cos(artg kt) (4.3)

QtMdk

cb

ktkkk

tgtg

).1((4.4)

Trong :

tg cb- h s cng sut phn khng c bn, trn thanh ci th cp trm bin p trung

gian.

Gi tr h s cng sut phn khng tg trn thanh ci h thng c xc nh trn c

s h s cos ca cc ngun in c xt n in dung ca ng dy.


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72

Bng 4.2H s cng sut phn khng c bn, ph thuc vo s cp in phn phi:

S cp in p

phn phi

2 cp

110/35/10

1 cp

110/(10-35)

Trc tip t my

pht

tg cb 0,4 0,425 0,55

cos cb 0,93 0,92 0,88

KtMh s tham gia vo cc i ca doanh nghip, c th tnh gn ng bng biu

thc:M

tMtM

P

Pk (4.5)

PtM- cng sut tiu th trung bnh trong thi gian cao im ca h thng.

PM- cng sut cc i ca doanh nghip.KQ- h s ng lng tiu chun b cng sut phn khng (kVAr/KW).

GQ- Gi thnh in nng phn khng, ng/kVArh.

H s ng lng kinh t cng sut phn khng c xc nh trn c s phn tch

hiu qu b ti u trn mng in phn phi. Nh bit, gi tr ng lng kinh

t b cng sut phn khng c xc nh theo biu thc:

dl

Qk

k1

(4.6)

Vi kld l t l cng sut tc dng c c do t b tnh trn mt n v cng sut

ca thit b b:

)2(2

Q

Q

U

QRk bdl (4.7)

Trong :

Q- Ph ti phn khng, kVAr.

R- in tr tnh t ngun n im t b.

Qb- cng sut ca thit b t b KVAr.


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73

U- in p nh mc ca mng in KV.

*Kt qu phn tch, tnh ton ng vi c im ca cc mng in cung cp cho cc

ph ti c trng cho thy c th ly gi tr trung bnh thng ca h s kQtheo bng

sau:

Bng 4.3 Gi tr trung bnh ca h s kQi vi cc ngnh sn xut:

Ch ph ti Cng nghip Nng nghip Thng mi v thnh phn

khc

KQ 0,55 0,5 0,45

Gi tr h s in kn th ph ti c xc nh trn c s s liu thng k v o

m ti cc x nghip c trng. Nhn chung gi tr h s in kn th ph ti thay

i ph thuc kh nhiu vo nhn t ca, kp lm vic, ma v, iu kin thi tit.

Bng 4.4Gi tr h s in kn th ph ti v h s tham gia cc i ca cc loi

ph ti c trng:

Loi ph ti c trng H s in kn ca ph ti H s tham gia vo cc iMt ca hai ca ba ca Mt ca hai ca ba ca

Cng nghip 0,35 0,65 0,75 0,65 0,75 0,75

Nng nghip 0,25 0,5 0,65 0,5 0,65 0,65

Thng nghip 0,35 0,55 0,7 0,65 0,85 0,85


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74

Bng 4.5 Gi tr h s cng sut ti thiu cos kti vi cc ph ti c trng ph

thuc vo ch lm vic theo ca:

S cp in p phnloi ph ti

Cos kt

phi Mt ca hai ca ba ca

hai cp

Cng nghip 0,92 0,9 0,88

Nng nghip 0,91 0,9 0,88

Thng nghip 0,91 0,9 0,87

Mt cp

Cng nghip 0,92 0,89 0,87

Nng nghip 0,9 0,89 0,86

Thng nghip 0,9 0,89 0,86

Phn tch cc kt qu tnh ton, ta nhn thy h s cos ti thiu ca cc loi ph ti

c trng khc so vi gi tr h s cos ti thiu hin ti ang p dng cho vic tnh

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