1. Thiết kế nhà máy Nhiệt Điện Ngưng Hơi

7/24/2019 1. Thit k nh my Nhit in Ngng H i

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1.2.1. Phutai cp in ap may phat (10,5 kV):Cng sut cc ai PUFmax= 64 MWHscosUF= 0,8th phu tai hnh H:1.1:Cng sut phu tai cp in ap may

phat c tnh theo cng thc sau:

UF

maxUFUF

cosP%.P)t(S

Trong o:SUF(t) la cng sut phu tai cp in

ap may phat tai thi im t.P% la phn trm cng sut phu tai

cp in ap may phat theo thi gian.PUFmax, cosUF la cng sut cc ai

va h s cng sut phu tai cp in ap

may phat.Ap dung cng thc (1.1) kt hp vi (H:1.1), ta cobang phn bcng sut phutaicp in ap may phat nh bang 1.2:

Bang 1.2t (h) 04 48 816 1618 1822 2224

SUF(t), MVA 72 64 80 64 56 72

1.2.2. Phutai cp in ap trung (110 kV):Cng sut cc ai PUTmax= 80 MWHscosUT= 0,85th phu tai hnh H:1.2:Cng sut phu tai cp in ap trung

c tnh theo cng thc sau:

UT

maxUT

UTcos

P%.P)t(S

Trong o:SUT(t) la cng sut phu tai cp in

ap trung tai thi im t.P% la phn trm cng sut phu tai

cp in ap trung theo thi gian.PUTmax, cosUTla cng sut cc ai va

hscng sut phutai cp in ap trung.

100

P%

80

60

40

20

0 4 8 12 16 20 24 t(h)H:1.1

(1.1)

(1.2)

100

P%

80

60

40

20

0 4 8 12 16 20 24 t(h)H:1.2


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Ap dung cng thc (1.2) kt hp vi (H:1.2), ta cobang phn bcng sut phutaicp in ap trung nh bang 1.3:

Bang 1.3t (h) 08 816 1620 2022 2224

SUT (t), MVA 75,294 94,118 84,706 75,294 65,882

1.2.3. Phutai cp in ap cao (220 kV):Cng sut cc ai PUCmax= 60 MWHscosUC = 0,85th phu tai hnh H:1.3:Cng sut phu tai cp in ap cao

c tnh theo cng thc sau:

UC

maxUC

UCcos

P%.P)t(S

Trong o:SUC(t) la cng sut phu tai cp in

ap cao tai thi im t.P% la phn trm cng sut phu tai

cp in ap cao theo thi gian.PUCmax, cosUC la cng sut cc ai

vahscng sut phutai cp in ap cao.Ap dung cng thc (1.3) kt hp vi (H:1.3), ta cobang phn bcng sut phutai

cp in ap cao nh bang 1.4:Bang 1.4

t (h) 04 412 1216 1624SUC (t), MVA 63,529 70,588 56,471 49,412

1.2.4. Cng sut tdung trong nhamay:Phutai tdung cua nha may c xac nh theo cng thc sau:

NM

FNMtd

S

)t(S.6,04,0.S.)t(S

Trong o:Std(t) lacng sut tdung cua nhamay tai thi im t.lahstdung cho nhamay, = 7%SF(t) lacng sut phat cua nhamay tai thi im t.SNMlacng sut t toan nhamay, SNM= 275 MVAV nhamay phat lun ht cng sut nn cng sut phat cua nhatai moi thi im t

la: SF(t) = SNM = 275 MVAAp dung cng thc (1.4) ta cocng sut tdung cua nhamay tai moi thi im t

u cc ai:

MVA25,19275

275.6,04,0.275%.7S)t(S maxtdtd

(1.3)

100

P

80

60

40

20

0 4 8 12 16 20 24 t(h)H:1.3

(1.4)


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1.2.5. Cng sut dtrquay cua hthng ni vi pha cao ap:Cng sut dtrquay cua hthng c xac nh theo cng thc sau:

SdtHT= Sdt% . SHT= 8% 2000= 160 MVA

1.2.6. Bang tng hp phn bcng sut trong toan nhamay:Nhamay ta lin hvi hthng valun phat ht cng sut. Vi phu tai lun Tin

ng theo thi gian v vy gia nhamay vahthng colin h vi nhau 1 lng cngsut vac xac nh nh sau:

Sth= SNM- [SUF(t)+ SUT(t) + SUC(t) + Std(t) ] = SNM- S(t)Qua tnh toan trn, ta lp c bang sliu cn bng cng sut cua toan nhamay

theo thi gian trong mt ngay nh bang 1.5.Bang 1.5

t (h) 04 48 812 1216 1618 1820 2022 2224SUF (t) 72 64 80 80 64 56 56 72SUT (t) 75,294 75,294 94,118 94,118 84,706 84,706 75,294 65,882SUC (t) 63,529 70,588 70,588 56,471 49,412 49,412 49,412 49,412Std (t) 19,25 19,25 19,25 19,25 19,25 19,25 19,25 19,25S(t) 230,073 229,132 263,956 249,839 217,368 209,368 199,956 206,544

SNM (t) 275 275 275 275 275 275 275 275Sth (t) 44,927 45,868 11,044 25,161 57,632 65,632 75,044 68,456

Tbang 1.5, ta thy trong iu kin lam vic bnh thng nha may in phat ucng sut cho phutai cac cp in ap vacon tha mt lng cng sut cotha lnhthng trong tt cacac thi im trong ngay. Do onha may cokhanng phat trinphutai cac cp in ap.

(1.5)


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th phu tai tng cua nhamay nh hnh H:1.4 sau:

0 t(h)244 8 12 16 20

20

80

240

280

40

60

100

260

220

200

180

160

140

120

S

SUT

SUF

Std

H:1.4

S (MVA)

SUC

275

230,073

75,29472

63,529

19,25


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1.3. XUT PHNG AN TNH TOAN.Chon s ni in chnh cua nha may lamt khu quan trong trong qua trnh

tnh toan thit k nhamay in. V vy cn nghin cu ky nhim vu thit k, nm vngcac sliu ban u. Da vao bang 1.5 vacac nhn xet tng quat, ta tin hanh xutcac png an ni dy coth. Cac phng an a ra phai am bao cung cp in lintuc cho cac phutai, phai khac nhau vcach ghep ni cac may bin ap vi cac cp in

ap, vslng vadung lng cua may bin ap, vslng may phat in, ... S ni in gia cac cp in ap phai am bao cac yu cu kythut sau:

- Smay phat ni vao thanh gop cp in ap may phat phai thoa man iu kinkhi ngng mt may phat ln nht th cac may phat con lai vn am bao cung cp ucho phutai cp in ap may phat vaphutai cp in ap trung.

- Cng sut bmay phat may - bin ap khng c ln hn dtrquay cua hthng SdtHT=8% . 2000= 160 MVA.

- Ch ni bmay phat may bin ap hai cun dy vao thanh gop in ap nao maphutai cc tiu o ln hn cng sut cua b nay; conh vy mi tranh c trng

hp luc phutai cc tiu, bnay khng phat ht cng sut hoc cng sut phai chuynqua hai ln bin ap lam tng tn tht vagy quatai cho may bin ap ba cun dy. ivi may bin ap tngu lin lac th khng cn iu kin nay.

- Khi phu tai cp in ap may phat nho cothly re nhanh tb may phat maybin ap nhng cng sut ly renhanh khng c vc qua15% cua b.

- May bin ap ba cun dy ch sdung khi cng sut truyn tai qua cun dy naykhng nhohn 15% cng sut truyn tai qua cun dy kia. ay khng phai laiu quinh mach laiu cn chuykhi ng dung may bin ap ba cun dy. Nh ta abit,tyscng sut cac cun dy cua may bin ap nay la100/100/100; 100/66,7/66,7 hay

100/100/66,7, ngha lacun dy co cng sut thp nht cung bng 66,7% cng sutnh mc. Do onu cng sut truyn tai qua mt cun dy nao oquanhosekhngtn dung c khanng tai cua no.

- Khng nn dung quahai may bin ap ba cun dy hoc tngu lin lac haytai in gia cac cp in ap.

- May bin ap t ngu ch s dung khi ca hai pha in ap cao va trung ap cotrung tnh trc tip ni t (U 110 kV).

- Khi cng sut tai ln in ap cao ln hn dtrquay cua h thng th phai t tnht hai may bin ap.

- Khng nn ni song song hai may bin ap hai cun dy vi may bin ap bacun dy v thng khng chon c hai may bin ap co tham sphu hp vi iu

kin vn hanh song song.

Thanh phn phn trm cng sut phutai cp in ap may phat so vi cng sut cuatoan nhamay:

%1,29100275

80100.

S

S%S

NM

maxUFUF


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Ta nhn thy rng, phutai cp in ap may phat ln hn 15% tng cng sut cuatoan nhamay nn cung cp cho nota phai xy dng thanh gop cp in ap mayphat.

Tyu cu kythut trn, ta xut ra mt sphng an ni in chnh cho nhamay nh sau:

1.3.1. Phng an I:1.3.1.1.

M taphng an:

- S gm 4 may phat F1, F2, F3, F4ni vao thanh gop cp in ap may phat.- Dung hai may bin ap tngu B1, B2lin lac gia cac cp in ap vagia

nhamay vi hthng.

1.3.1.2.u im:

- S am bao slin lac gia cac cp in ap vagia nhamay vi hthng.Nu hong mt may th cac tmay khac vn lam vic song song.

- Slng may bin ap tng t nn giathanh khng cao, n gian trong vic lpt, mt bng lp t ngoai tri nho.

1.3.1.3.Nhc im:

- V nhiu tmay c ni vao thanh gop nn phai btr mach vong do o hthng thanh gop cp in ap may phat rt phc tap.

- Thanh gop cp in ap may phat ni vong nn tnh toan Bao VRLe phc tap.

220 kV

110 kV

B1 B2

F4F3F1 F2

10,5 kV

HT

H:1.5


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1.3.2. Phng an II:1.3.2.1.M taphng an:

- S gm 3 may phat F1, F2, F3 ni vao thanh gop cp in ap may phat.- Dung hai may bin ap tngu B1, B2lin lac gia cac cp in ap vagia

nhamay vi hthng.- Mt bmay phat F4 - may bin ap hai cun dy B3ni vathanh gop cp in ap

trung.

1.3.2.2.u im:

- S am bao slin lac gia cac cp in ap vagia nha may vi hthng.- May bin ap ni vao thanh gop cp in ap trung nn giathanh may bin ap va

cac thit b t tn kem hn so vi bn cao ap.- Slng may phat ni vao thanh gop cp in ap may phat t nn thanh gop

n gian.1.3.2.3.Nhc im:

- Slng may bin ap nhiu dn n vn u t tng, mt bng phn bthit bngoai tri ln.

1.3.3.

Phng an III:1.3.3.1.M taphng an:- S gm 2 may phat F1, F2 ni vao thanh gop cp in ap may phat.- Dung hai may bin ap tngu B1, B2lin lac gia cac cp in ap vagia

nhamay vi hthng.- Hai bmay phat F3 - B3, F4 - B4tng ng ni vathanh gop cp in ap trung

vacp in ap cao.

220 kV 110 kV

B1 B2

F4F3F1 F2

10,5

HT

H:1.6

B3


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1.3.3.2.u im:

- S am bao yu cu cung cp in, tin cy cung nh slin lac gia caccp in ap vi nhau vagia nhamay vi hthng.

- May bin ap tngu c chon cocng sut nhodo cothm bmay phat - maybin ap ni bn cao.

- Slng may phat ni vao thanh gop cp in ap may phat t nn thanh gopn gian.

1.3.3.3.

Nhc im:- Slng may bin ap nhiu dn n mt bng phn bthit b ngoai tri ln va

sekhokhn hn cho vic bao dng nh kyMBA lin lac- V cobmay phat - may bin ap hai cun dy ni pha cao nn tn kem v

phai dung thit b cocach in cao.- Slng may bin ap hai cun dy nhiu nn tn km.

1.3.4. Phng an IV:1.3.4.1.M taphng an:

- S gm 3 may phat F1, F2, F3 ni vao thanh gop cp in ap may phat.- Dung hai may bin ap tngu B1, B2lin lac gia cac cp in ap vagia

nhamay vi hthng.- Hai bmay phat F4 - B3ni vathanh gop cp in ap cao.

220 110

B1 B2

F3F2F1

10,5

HT

H:1.7

B3

F4

B4


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1.3.4.2.u im:

- S am bao slin lac gia cac cp in ap vagia nha may vi hthng.- Slng may phat ni vao thanh gop cp in ap may phat t nn thanh gop

n gian.1.3.4.3.Nhc im:

- V b may phat - may bin ap hai cun dy ni pha cao nn tn kem v phaidung thit b cocach in cao.

- Slng may bin ap nhiu dn n mt bng phn phi thit b ngoai tri ln.

1.3.5. Nhn xet chung:Qua phn tch u, nhc im cua tng phng an, ta nhn thy phng an I am

bao v mt kythut nht vaconhiu u im hn nn ta chon phng an I tnh toancho cac phn tip theo.

220 kV 110 kV

B1 B2

F3F1

10,5 kV

HT

H:1.8

F4

B3

F2


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Chng 2: TNH CHON MAY BIN AP, TNH TN THT INNNG, CHON KHANG IN PHN OAN

2.1. CHON MAY BIN AP.May bin ap lamt thit b chnh trong nhamay in, vn u t cua nochim

mt phn rt quan trong trong tng svn u t cua nha may. V vy vic chon s

lng vacng sut nh mc cua chung lart quan trong. Cng sut cua may bin apc chon phai bao am u cung cp in theo yu cu phu tai khng nhng trongiu kin lam vic bnh thng mangay caluc sc. Chnh mc cua may binap phuthuc vao nhit mi trng nhng do t hang theo iu kin kh hu tai nilp t nn khng cn hiu chnh theo nhit .

2.1.1. Chon may bin ap cho phng an I:

2.1.1.1.Chon may bin ap lin lac B1, B2.2.1.1.1.1. Chon cng sut may bin ap lin lac B1, B2:

May bin ap lin lac lamay bin ap tngu, cng sut c chon theo iu kintai ht cng sut tha tthanh gop cp in ap may phat:

SHmB1 = SHmB2= Smu= Kcl. SmB1 2

1 . Sthmax

Trong o:

Sthmax=4

1

SmFi-4

1

StdFimax- SUFmin=4.68,75 - 19,25 - 56 = 199,75 MVA

Vi: 4

1

SmFilatng cng sut nh mc cua may phat F1, F2, F3, F4

(2.1)

220 kV

110 kV

B1 B2

F4F3F1 F2

10,5 kV

HT

H:2.1


13/77 13

4

1

StdFimaxlacng sut tdung ln nht cua may phat F1, F2, F3, F4

SUFminlacng sut cc tiu cua phu tai cp in ap may phat.Kcl: Lahscoli cua may bin ap tngu.

5,0220

110220

U

UUK

C

TC

cl

Nh vy, cng sut cua may bin ap ln lac B1 vaB2laSmB1 = SmB2 75,199

5,0

75,199.

2

1 (MVA)

Tra sach Thit k phn in trong nha may in va tram bin ap cua PGSNguyn Hu Khai, ta cothng smay bin ap B1 vaB2 nh bang 2.1.

Bang 2.1

LoaiMBA

SmMVA

in ap cundy, kV

PokW

PN, kW UN% Io%

C T H C-T C-H T-H C-T C-H T-HATTH 200 230 121 11 105 430 11 32 20 0,5

2.1.1.1.2. Kim tra may bin ap:

a. Kim tra quatai bnh thng:V cng sut nh mc cua may bin ap B1, B2c chon ln hn cng sut tnh

toan nn khng cn kim tra quatai bnh thng.b. Kim tra quatai sc:

Giasscmay bin ap B1th may bin ap B2con lai vi khanng quatai sccho phep phai cung cp u cng sut phu tai cp in ap trung, cao luc cc ai. Ngha

la:sc

qtK. Kcl.SmB2 [SUTmax+ (SUCmax- SdtHT)]V: SUCmax- SdtHT = 70,588 - 160 = -89,412< 0 tc lahthng ucung cp cho

phutai cp in ap cao. Do oiu kin (2.2) trthanh:sc

qtK. Kcl.SmB2 SUTmax

Vtrai: scqt

K. Kcl.SmB2= 1,2.0,5.200 = 120 MVAVphai: SUTmax= 94,118 MVAVy (2.3) athoa man.

2.1.1.2.Kt lun:Cac may bin ap achon thoa man iu kin lam vic bnh thng vasc.

2.2. TNH TN THT IN NNG TRONG MAY BIN AP.Tn tht in nng trong may bin ap gm 2 phn:- Tn tht khng tai khng phuthuc vao th phutai.- Tn tht tai phuthuc vao th phutai.

(2.2)

(2.3)


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2.2.1. Phng an I:

2.2.1.1.Tn tht in nng qua may bin ap lin lac B1, B2:

V hai may bin ap B1, B2 lahai may bin ap tngu ging nhau vn hanh song songvath phutai cua ta lath bc thang nn ta sdung cng thc (2.9) sau:

Trong o:n lasmay bin ap lam vic song songSCi, STi, SHilacng sut qua cun cao, cun trung, cun haap cua n may bin

ap bin ap tngu.PNC, PNT, PNHlatn tht ngn mach trong cun dy in ap cao, trung, ha

cua may bin ap tngu.Polatn tht khng tai cua may bin ap.

Ch coPNC-T= 430 kW, do ocothxem:

PNC-H = PNT-H=2

1 .PNC-T=2

1 .430 =215 kW

=Kcl= 0,5

V nhamay lun phat ht cng sut cung cp cho cac phu tai vacon tha tai moithi im trong ngay nn cng sut qua cac cun dy may bin ap t ngu:

STi(t) = SUT(t)

SHi(t)= 4

1SmFi-

4

1StdFi max- SUF(t)

SCi(t) = SHi(t) - STi(t)

iNH

2

1mB

Hi

iNT

2

1mB

Ti

iNC

2

1mB

Ci

o2B,1B t.P.

S

St.P.

S

St.P.

S

S

n

1t.P.nA

Vy: kW

kW

kW645430)5,0(

215

)5,0(

215.5,0P

215)5,0(

215

)5,0(

215430.5,0P

215)5,0(

215)5,0(

215430.5,0P

22NH

22NT

22NC

TNCHNTHNC

NH

HNCHNTTNCNT

HNTHNC

TNCNC

PPPP

PPPP

PP

PP

22

22

22

.5,0

.5,0

.5,0

(2.10)

(2.9)


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Bang 2.4t (h) 04 48 816 1618 1820 2022 2224

SUF(t) 72 64 80 64 56 56 72SH(t) 183,75 191,75 175,75 191,75 199,75 199,75 183,75ST(t) 75,294 75,294 94,118 84,706 84,706 75,294 65,882SC(t) 108,456 116,456 81,632 107,044 115,044 124,456 117,868

Tn tht in nng cua may bin ap B1, B2trong mt ngay:

Ang = 2.105.24+ 2200.21 .(215.262,760 + 215.211,292 + 645.829,898).103

Tn tht in nng cua may bin ap B1, B2trong mt nm:AB1,B2 = Ang.365 = 13005.365 = 4746,825.103kWh = 4746,625 MWh

Tn tht in nng hang nm:A = AB1,B2= 4746,625 MWh

2.3. TNH CHON KHANG IN PHN OAN.Khang in lamt cun dy khng coloi thep, in khang Xkln hn in trrk

rt nhiu. Khang in phn oan nhm muc ch han chdong ngn mach khi ngnmach trn cac phn oan vatao in ap d trn phn oan kkhi ngn mach trn phnoan o. Tuy nhin khang in vn conhc im lagy ra tn tht in ap khi lamvic bnh thng vacng bc.

Khi phn bphutai cp in ap may phat ta cn phn bphutai vao phn oankhng ni trc tip vi may bin ap nhiu hn phn oan coni trc tip vi may binap. Muc ch khi lam vic dong qua khang valch pha gia cac phn oan lanhonht. Tuy nhin phn oan co nhiu phutai ni vao b scth slng tai b mtin seln.

=13005 kWh

i2Ti t.S(MVA)2.h3

2222

10.292,211

2.)882,165(4.)706,84(8.)118,94(10.)294,75(

(MVA)2.h32222222

10.760,2622.)868,117(2.)456,124(

2.)044,115(2.)044,107(8.)632,81(4.)456,116(4.)456,108(

i2

Ci t.S

i2

Hi t.S

(MVA)2.h32222

10.898,829

4.)75,199(8.)75,175(6.)75,191(6.)75,183(


16/77 16

2.3.1. Chon khang in phn oan cho phng an I:

2.3.1.1.Xac nh dong in lam vic tnh toan:

2.3.1.1.1. Phn bphutai cp in ap may phat cho cac phn oan:

Theo hnh H:2.3, ta co

SP1max= SP3max= 5,128,0

10

Cos

P max1P

MVA

SP2max= SP4max= 5,278,0

22

Cos

P max2P

MVA

SP1min= SP3min= 70%.SP1max= 8,75 MVA

SP2min= SP4min= 70%.SP2max= 19,25 MVA2.3.1.1.2. Dong in lam vic bnh thng qua khang:

2.3.1.1.3.

Dong in lam vic cng bc qua khang:a.Khi mt tmay phat F1(hoc F3) ngh lam vic:

SK1= SK4=2

1 .(SBA+ SP1)

H:2.3

MVA

3442225194

125197568

2

1

2

1222

,,.,,

SSS maxtdFminPmF

bt4K

bt

3K

bt

2K

bt

1K SSSS

bt

4K

bt

3K

bt

2K

bt

1K IIII 2291

5103

34422

3

1 ,,.

,U

S

F

btK kA


17/77 17

-Khi phutai cp in ap may phat cc ai:

-Khi phutai cp in ap may phat cc tiu:

b. Khi ngng mt tmay phat F2(F4):

c. Khi ngng lam vic mt may bin ap tngu B1(hoc B2):

3mFmax3tdFmax3PBA4K3K

SSSS.2

1SS

Trong o:SBA= min {Sthmax, SHmax}

Vi: SHmax= scqtK .Smu = scqtK .Kcl.SmB2 = 1,2.0,5.200 = 120 MVA

d. Khi scK2hoc K3 (c mach vong):

SK3=SmF2- StdF2max- SP2min= 68,75 -4

1 .19,25 -19,25 = 44,688 MVA

Vy cng sut cng bc ln nht chay qua khang K1, K2, K3, K4:

2.3.1.2.Chon khang in:

Tra sach Thit k phn in trong nha may in va tram bin ap cua PGSNguyn Hu Khai, ta cothng skhang in K1, K2 , K3, K4 nh bang 2.6.

MVA906,6725,19.4

35675,68.3

2

1

SSS.2

1 3

1

maxtdminUF

3

1

mFi

)2(BAS

MVA906,5525,19.4

38075,68.3

2

1

SSS.2

1 3

1

maxtdmaxUF

3

1

mFi

)1(BAS

MVA 055,345,12609,55.2

1SS.

2

1max1P

)1(

BA )1(

4K

)1(

1K SS

MVA 18,3875,8609,67.2

1SS.

2

1min1P

)2(

BA )2(

4K

)2(

1K SS

MVA 156,1625,19.415,27.

21SS.

21

max2tdFmax2P

2K1K SS

MVA281,3475,6825,19.4

15,12120.

2

1

4K3K SS

MVA

Sthmax

75,19925,195675,68.4

SSS4

1

tdFiminUFmFi

4

1

kAcb

K

cb

K

cb

K

cb

K IIII 4321 457,25,10.3

688,44

3

max

F

cb

U

SMVA688,44Scb

max


18/77 18

Bang 2.6

Loai khang inUmkA

ImkA

XK

Pm1pha, kW

IokA

IonhkA

PbA-10-3000 10 3 0,23 25,7 53 42

2.3.1.3.Kim tra tn tht in ap:

2.3.1.3.1.

iu kin lam vic bnh thng:Chon %XK =12%:

%2%95,26,0.3

229,1%.12sin.%.

mK

btK

KbtK I

IXU (khng thoa)

(Vi:cos= 0,8 sin =0,6)Chon %XK =10%:

%2%458,26,0.3

229,1%.10sin.%.

mK

btK

KbtK I

IXU (khng thoa)

Chon %XK =8%:

%2%966,16,0.3

229,1%.8sin.%.

mK

btK

KbtK I

IXU (thoa)

2.3.1.3.2. iu kin lam vic cng bc:

%5%931,36,0.3

457,2%.8sin.%.

mK

cbK

KcbK I

IXU (thoa)

Vy chon khang in co %XK =8% thoa man yu cu vtn tht in ap.


19/77 19

Chng 3: TNH TOAN NGN MACH

3.1. MU.Ngn mach lamt loai scxay ra trong hthng in do hin tng cham chp

gia cac pha, khng thuc chlam vic bnh thng. Chung ta cn phai dbao cactnh trang ngn mach co thxay ra vaxac nh dong in ngn mach tnh toan tng

ng.Muc ch tnh dong ngn mach lachon cac kh cuin, cac thanh phn co dongin chay qua va kim tra cac phn t o am bao n nh ng va n nh nhit.

Ngoai ra, cac sliu vdong in ngn mach lacn cqua trong thit khthngbao vrle van nh phng thc vn hanh hthng.

Phng phap tnh toan ngn mach y, ta chon phng phap ng cong tnhtoan. im ngn mach tnh toan laim makhi xay ra ngn mach tai oth dong ngnmach i qua kh cuin laln nht. V vy vic lp s tnh toan dong in ngnmach i vi mi kh cuin cn chon mt ch lam vic nng nnht nhng phai

phuhp vi iu kin thc t.3.2. TNH TOAN NGN MACH CHO PHNG AN I.

3.2.1. S thay thnhamay in vacac im ngn mach tnh toan:3.2.1.1.S tnh toan:

H:3.1F2

B1 B2

F3 F4F1

N3

HT

N4

N5

N5~ ~ ~ ~

K1 K2 K3 K4

N1 N2

N6

N6

N4

N8N7


20/77 20

3.2.1.2.Cac im ngn mach:

3.2.1.2.1. im N1:

- Muc ch:chon vakim tra kh cuin cac mach pha cao ap.- Trang thai s : Tt cacac may phat, may bin ap vahthng ang vn hanh

bnh thng.3.2.1.2.2. im N2:

- Muc ch:chon vakim tra kh cuin cac mach pha trung ap.- Trang thai s : Tt cacac may phat, may bin ap vahthng ang vn hanh

bnh thng.3.2.1.2.3. im N3:

- Muc ch:chon vakim tra kh cuin mach haap may bin ap.- Trang thai s : Tt cacac may phat vahthng ang vn hanh bnh thng

ch comay bin ap B1ngh.3.2.1.2.4. im N4, N4:

- Muc ch:chon vakim tra kh cuin cho mach phn oan.- Trang thai s :

+im N4: Tt cacac may phat vahthng ang vn hanh bnh thng, mayphat F1vamaybin ap B1ngh.

+im N4: Tt cacac may phat vahthng ang vn hanh bnh thng,mayphat F2vaK2(hoc K3) ngh.

3.2.1.2.5. im N5, N5, N6, N6:

- Muc ch:chon vakim tra kh cuin cho mach may phat.- Trang thai s :

+im N5: Ch co may phat F1lam vic.+im N5: Tt cau lam vic bnh thng, tr may phat F1ngh.+im N6: Ch co may phat F2lam vic.+im N6: Tt cau lam vic bnh thng, tr may phat F2ngh.3.2.1.2.6. im N7, N8:

- Muc ch:chon vakim tra kh cuin cho mach tdung vamach phu taicp in ap may phat.

- Trang thai s : Tt cacac may phat, may bin ap vahthng ang vn hanhbnh thng.

Ts hnh H:3.1 va giathit tnh toan ngn mach ta co:


21/77 21

'

'

668

557

543

NNN

NNN

NNN

IIIIIIIII

3.2.1.3.S thay th: Vi E1= E2= E3= E4= E (cac may phat nh nhau)

3.2.2. Tnh toan cac thng scua s thay th:3.2.2.1.Cac ai lng c ban:

Chon cac ai lng c ban:Scb= 100 MVAUcb= Utbcac cp in ap

5,10cbU = 10,5 kV kA,

,.U.SI

,cb

cb,cb 4995

5103

100

3 510510

110cbU = 115 kV kA,.U.SI

cb

cbcb 5020

1153

100

3 110110

220cbU = 230 kV kAUSI

cb

cbcb 251,0

230.3

100

.3220

220

3.2.2.2.

Cac thng scua s thay th:3.2.2.2.1. in khang cua may phat F1, F2, F3, F4:

cbF *X =X1= X2= X3= X4= 1978,075,68

100.136,0.

" mF

cbd S

SX

3.2.2.2.2. in khang cua khang in phn oan:

cbK *X = X5= X6= X7= X8= 1466,03

499,5.

100

8.

100

% 5,10 mK

cbK

IIX

H

E

E E EH:3.2

002,0

16X

0567,0

15X

0575,0

14X0575,0

13X

0

11X0

12X

1025,0

9X1025,0

10X

1466,0

5X1466,0

8X

1466,0

6X1466,0

7X

1978,0

1X1978,0

2X1978,0

3X

1978,0

4X

(Theo Nguyn lyxp chng)


22/77 22

3.2.2.2.3. in khang cua may bin ap lin lac B1,B2:

- in khang cua cun ha:

- in khang cua cun trung:

- in khang cua cun cao:

3.2.2.2.4. in khang cua ng dy lin lac vi hthng:

cbD*X = X15= 0567,0

230

100.

2

150.4,0

U

S.

2

l.X22

220cb

cb0

3.2.2.2.5. in khang cua hthng:

HT

cbmHTcbHT S

S.*XX*X 16

Ta co: 15100

2500

S

S*S

cb

N

N

04025

11 ,*S*I

*U*XNHT

HTmHT (V *IHT = *SN )

00202000

10004016 ,.,S

S.*XX*XHT

cbmHTcbHT

109cbH XX*X

1025,0200

100.112032.

200

1

.%%%.200

1

mB

cbTNCHNTHNC S

SUUU

1211cbT XX*X

0200

100322011

200

1

200

1

..

SS.%U%U%U.

mB

cbHNCHNTTNC

0575,0200

100.203211.

200

1

.%%%.200

1

mB

cbHNTHNCTNC S

SUUU1413cbC XX*X


23/77 23

3.2.3. Tnh toan dong ngn mach:3.2.3.1.im ngn mach N1:

3.2.3.1.1. S bin i:

Ts (H:3.3a), ta co:X17= X15+ X16= 0,0567 + 0,002 = 0,0587

V s (H:3.3a) i xng nhau qua im ngn mach N1nn ta cos (H:3.3b)vagiatr in khang nh sau:

X18=2

X1 =

2

1978,0 =0,0989 ; X21=2

9X =2

1025,0 =0,0513.

X19= X20=2

X6 =

2

1466,0 =0,0733 (X5= X6= X7= X8)

H:3.3

E

HT

E E E

N1

0587,0

17X

0575,0

14X0575,0

13X

1025,0

9X

1466,0

5X1466,0

8X

1466,0

6X1466,0

7X

1978,0

1X

1978,0

2X 1978,03X

1978,0

4X1025,0

10XE

E E

HT

H:3.3b

N1

0587,0

17X

0288,0

22X

0513,0

21X

0733,0

20X

0733,0

19X

0989,0

18X1978,0

2X

1978,0

4X

E

E

HT

E

H:3.3c

N1

0587,0

17X

271,0

24X

271,0

25X0989,0

18X

08,0

23X

E

HT

E

H:3.3d

N1

0587,0

17X

08,023X

271,0

24X

0725,0

26X

E

HT

H:3.3e

N1

0587,0

17X

137,0

27X


24/77 24

X22=2

X13 =

2

0575,0 =0,0288

Ts (H:3.3c), ta co:X23= X22+ X21= 0,0288 + 0,0513 = 0,08X24= X4+ X20= 0,1978 + 0,0733 = 0,271X25= X2+ X19= 0,1978 + 0,0733 = 0,271

Ts (H:3.3d), ta co:X26=

1825

1825

XX

X.X

=

0989,0271,0

0989,0.271,0

=0,0725

Ts (H:3.3e), ta co:

X27= X23+2624

2624

XX

X.X

=0,08 +

0725,0271,0

0725,0.271,0

=0,137

3.2.3.1.2. Tnh dong ngn mach:

s dung ng cong tnh toan, ta qui i in khang tnh toan v h n vtng i nh mc ( mtt *X )

mtt *X =X27.cb

mFi

SS =0,137.

100

275 =0,377

Tra ng cong tnh toan (hnh 3.5 trang 46 sach Thit kphn in trong nhamay in va tram bin ap cua PGS Nguyn Hu Khai), ta c bi scua thanh phnkhng chu kydong in ngn mach:

"K0 =2,7 ;"K =2,07

Dong siu quaban u do cac may phat in cung cp:"I0 =

"K0 . mFI ="K0 .

220.3 cb

mFi

U

S =2,7.2303

275

.=1,864 kA

Dong ngn mach duy tr cac do may phat in cung cp:"I =

"K . mFI = "K .2203 cb

mFi

U.S =2,07.

2303

275

.=1,429 kA

Dong ngn mach do h thng cung cp:

HI =H

cb

XI 220 =

17

220

XIcb =

05870

2510

,, =4,276 kA

Tr sdong ngn mach tai im N1:"

NI 10 ="I0 + IH=1,864 + 4,276 = 6,14 kA

"NI 1 = "I + IH=1,429 + 4,276 = 5,705 kADong ngn mach xung kch tai N1:

kAIKi NxkxkN 63,1514,6.8,1.2..2 "

0 11

Trong oKxklahsxung kch, phuthuc vao chngn mach, c tra bang3.3 trang 44 sach Thit kphn in trong nhamay in vatram bin ap cua PGS

Nguyn Hu Khai.Giatr hiu dung cua dong ngn mach xung kch tai N1:

kAKII xkNxkN 271,9)18,1.(21.14,6)1.(21. 22"

0 11


25/77


26/77 26



mtt *X =X29.cb

mFi

SS =0,1085.

100

275 =0,298


"K0 =3,4 ;"K =2,27


"K0 . mFI ="K0 .

1103 cb

mFi

U.S =3,4.

1153

275

.=4,694 kA


"K . mFI = "K .1103 cb

mFi

U.

S =2,27.1153

275

.

=3,134 kA


HI =H

cb

XI

110 =28

110

XIcb =

08750

5020

,, =5,737 kA


NI 20 ="I0 + IH=4,694 + 5,737 = 10,431 kA

"NI 2 =

"I + IH=3,134 + 5,737 = 8,871 kADong ngn mach xung kch tai N2:

kAIKi NxkxkN 553,26431,10.8,1.2..2 "

0 22

Giatr hiu dung cua dong ngn mach xung kch tai N2:kAKII xkNxkN 75,15)18,1.(21.431,10)1.(21.

22"

0 22


27/77 27

3.2.3.3.im ngn mach N4:

3.2.3.3.1. S bin i:

Ts (H:3.5a), ta co:X17= 0,0587 (atnh trn)

Ts (H:3.5b), ta co:X30= X10+ X14 + X17=0,1025 + 0,0575 + 0,0587 = 0,2187

0535,01466,01978,01978,0

1466,0.1978,0.

732

72

31

XXXXXX

0722,01466,01978,01978,0

1978,0.1978,0.732

3232 XXX XXX

05350146601978019780

1466019780

732

73

33,

,,,,.,

XXXX.XX

Ts (H:3.5c), ta co:

34X

H:3.5a

HT

N

E

E E

0575,0

14X

0587,0

17X

1025,0

10X

1978,0

4X

1978,0

2X1978,0

3X1466,07X

1466,0

8X1466,0

5X

1466,0

6X H:3.5b

HT

E

E

N4

1466,0

6X

1466,0

5X1978,0

4X

1466,0

8X2187,0

30X

0535,0

31X0722,0

32X

0535,0

33X

H:3.5c

HTE

E

N4

E

2187,0

30X

542,0

34X 402,0

35X

402,0

38X5422,0

37X5422,036X

N4

H:3.5d

HT

E E

2187,0

30X

201,0

39X

271,0

40X5422,0

37X

H:3.5e

E

HT

N45,0

41X

242,1

42X

271,0

40X

E

HT

H:3.5f

N4

5,0

41X

222,0

43X

542,0

0535,0

0535,0.0535,01466,00722,00535,01466,0

.

33

32316

32316

XXXXXXX


28/77 28

5422014660

146601978014660197808

545436 ,, ,.,,,XX.XXXX

5422014660

14660197801466019780

5

84

8437 ,,,.,,,

XX.XXXX

402019780

14660146601466014660

4

85

8538,

,,.,,,

XX.XXXX

Ts (H:3.5d), ta co:

201,0402,0402,0

402,0.402,0.

3835

383539

XX

XXX

271,0542,05422,0

542,0.5422,0.

3436

343640

XX XXX

Ts (H:3.5e), ta co:

5,05422,0

201,0.2187,0201,02187,0

.

37

3930393041

X

XXXXX

242,12187,0

201,0.5422,0201,05422,0

.

30

3937

393742

XXXXXX

Ts (H:3.5e), ta co:

222,0242,1271,0

242,1.271,0.

4240

4240

43

XX

XXX



mtt *X =X43.cb

mFi

SS =0,222.

100

25,206 =0,458


"K0 =2,22 ;"K =1,91


"K0 . mFI ="K0 .

5103 ,cb

mFi

U.S =2,22.

5,10.3

25,206 =25,177 kA

35X

402,0

0722,0

0535,0.0535,01466,00535,00535,01466,0

.

32

33316

33316

XXXXXXX


29/77 29


"K . mFI = "K .510

3 ,cb

mFi

U.S =1,91.

5,10.3

25,206 =21,661 kA


HI =H

,cb

XI 510 =

41

510

XI ,cb =

5,0

499,5 =11 kA


NI 40 ="I0 + IH=25,177 + 11 = 36,177 kA

"NI 4 =

"I + IH=21,661 + 11 = 32,661 kADong ngn mach xung kch tai N4:

kAIKi NxkxkN 092,92177,36.8,1.2..2 "

0 44


22"

04 4


3.2.3.4.1. S bin i:HT

E E

H:3.6a

E

N4

0587,0

17X

0575,0

14X0575,0

13X

1025,0

9X

1466,0

5X1466,0

8X

1466,0

7X

1978,0

1X1978,0

3X

1978,0

4X1025,0

10X

H:3.6b

HT

N4

1025,0

9X

0535,0

46X

1466,0

8X

1466,0

7X0722,047X

1978,0

3X

0535,0

45X 1025,010X

E

E

0875,0

44X


30/77 30


Ts (H:3.6b), ta co:

X44= X17+2

14X =0,0587 +2

0575,0 = 0,0875

0535,01466,01978,01978,0

1466,0.1978,0.

541

54

45

XXXXXX

0535,01466,01978,01978,0

1466,0.1978,0.

541

51

46

XXXXXX

0722,01466,01978,01978,0

1978,0.1978,0.

541

41

47

XXXXXX

Ts (H:3.6c), ta co:X48= X9+ X46= 0,1025 + 0,0535 = 0,156

X49= X45+ X8= 0,0535 + 0,1466 = 0,2Ts (H:3.6d), ta co:

0304,02,00722,01978,0

0722,0.1978,0.

49473

47350

XXX

XXX

0307,02,00722,01978,0

2,0.0722,0.

49473

494751

XXX

XXX

E

HT

H:3.6g

N4

638,0

59X

329,0

60X

H:3.6c

HT

N4

0875,0

44X

156,0

48X

1466,0

7X

0722,0

47X

1978,0

3X

2,0

49X 1025,010X

E

E

HT

N4E

1388,0

57X

0716,0

58X1697,0

56X

HT

H:3.6f

H:3.6d

N41466,0

7X

0304,0

50X

1025,0

10X

E

0842,0

52X

0307,0

51X

0875,0

44X

156,0

48X

N4

1466,0

7X

E

0513,0

53X

0412,054X

0231,0

55X

HT

H:3.6e

0875,0

44X

0304,0

50X


31/77 31

0842,02,00722,01978,0

2,0.1978,0.

49473

49352

XXX

XXX

Ts (H:3.6e), ta co:

0513,00842,00307,0156,01025,0

1025,0.0307,0156,0.

52514810

10514853

XXXX

XXXX

0421,0

0842,00307,0156,01025,0

0842,0.0307,0156,0.

52514810

525148

54

XXXX

XXXX

0231,00842,00307,0156,01025,0

0842,0.1025,0.

52514810

521055

XXXX

XXX

Ts (H:3.6f), ta co:X56= X7+ X55= 0,1466 + 0,0231 = 0,1697X57= X44+ X53= 0,0875 + 0,0513 = 0,1388X58= X50+ X54= 0,0304 + 0,0412 = 0,0716

Ts (H:3.6g), ta co:

638,0

0716,0

1388,0.1697,01388,01697,0

.

58

5756575659

X

XXXXX

329,01388,0

0716,0.1697,00716,01697,0

.

57

5856585660

X

XXXXX


s dung ng cong tnh toan, ta qui i in khang tnh toan v h n vtng i nh mc ( mttX * )

mttX * =X60.cb

mFi

SS =0,329.

100

25,206 =0,679


"K0 =1,47 ;"K =1,52


"K0 . mFI ="K0 .

5103 ,cb

mFi

U.S =1,47.

5,10.3

25,206 =16,671 kA


"K . mFI = "K .5103 ,cb

mFi

U.

S =1,52.5,10.3

25,206 =17,238 kA


HI =H

,cb

XI 510 =

59

5,10

XIcb =

638,0

499,5 =8,619 kA


'0 4NI = "I0 + IH=16,671 + 8,619 = 25,29 kA

"

'4NI =

"I + IH=17,238 + 8,619 = 25,857 kA


32/77 32

Dong ngn mach xung kch tai N4:kAIKi NxkxkN 378,6429,25.8,1.2..2

"

'0' 44


22"

'0' 44

3.2.3.5.im ngn mach N5, N6 (V cac may phat nh nhau):

3.2.3.5.1.

S bin i:



mttX * =X1.cb

mFi

SS =0,1978.

100

75,68 =0,134


"K0 =7,5 ;"K =2,7

Tr sdong ngn mach tai im N5, N6:"

0 5NI = "

0 6NI = "K0 . mFI =

"K 0 .5103 ,cb

mFi

U.S =7,5.

5,10.3

75,68 =28,352 kA

"

5NI =

"

6NI =

"K . mFI = "K .5103 ,cb

mFi

U.

S =2,7.5,10.3

75,68 =10,206 kA

Dong ngn mach xung kch tai N5, N6:kAIKii NxkxkNxkN 583,76352,28.91,1.2..2

"

0 565

Giatr hiu dung cua dong ngn mach xung kch tai N5, N6:kAKIII xkNxkNxkN 208,46)191,1.(21.352,28)1.(21.

22"

0 565

E N51978,0

1X


33/77 33


3.2.3.6.1. S bin i:


Ts (H:3.8b), ta co:- Cac giatr atnh trn:

X44= 0,0875 ; X36= 0,5422

H:3.8a

E

HT

E E

N5

0587,0

17X

0575,014X0575,0

13X

1025,0

9X

1466,0

5X1466,0

8X

1466,0

6X1466,0

7X

1978,0

2X 1978,03X

1978,0

4X1025,0

10X

H:3.8b

E

HT

H:3.8f

N5

199,0

71X

14,0

72X

H:3.8e

199,0

71XHT

N5

EE289,0

70X

271,0

64X

0507,0

68X

H:3.8d

HT

N5 EE

0507,0

69X0259,0

67X

114,0

66X271,0

64X

0875,0

44X

E

0875,0

44X

5422,0

36X5422,0

37X

5422,0

63X5422,0

61X 402,062X

402,0

38X

1025,0

9X1025,0

10X

1978,0

3X

HT

E E

EE

N5

E

0875,0

44X

271,0

64X201,0

65X

1025,0

9X1025,0

10X

HT

E

N5H:3.8c

114,0

66X


34/77 34

X37= 0,5422; X38= 0,402- Cac giatr con lai:

5422,01466,0

1466,0.1978,01466,01978,0

.

7

62

6261

XXXXXX

402,01978,0

1466,0.1466,01466,01466,0

.

2

767662

X

XXXXX

5422,01466,0

1466,0.1978,01466,01978,0.

6

72

7263 XXXXXX

Ts (H:3.8c), ta co:

271,02

5422,0

2

36

64

XX

201,02

402,0

2

38

65

XX

114,0

1978,02

5422,0

1978,0.2

5422,0

2

.2

3

37

3

37

66

XX

XX

X

Ts (H:3.8d), ta co:

0259,0201,01025,01025,0

1025,0.1025,0.

65109

10967

XXX

XXX

0507,0201,01025,01025,0

201,0.1025,0.

65109

6510

68

XXXXXX

0507,0201,01025,01025,0

201,0.1025,0.

65109

65969

XXX

XXX

Ts (H:3.8e), ta co:

Ts (H:3.8f), ta co:

14,0289,0271,0

289,0.271,0.

7064

7064

72

XXXXX

70X

289,0

0259,00875,0

0507,0.0507,0114,00507,00507,0114,0

.

6744

696866

696866

XXXXXXXX

199,00507,0114,0

0507,0.0259,00875,00507,00259,00875,0

.

6866

696744

696744

XX

XXXXXX71X


35/77 35



mttX * =X72.cb

mFi

SS =0,14.

100

25,206 =0,289


"K0 =3,4 ;"K =2,28


"K0 . mFI ="K0 .

5103 ,cb

mFi

U.S =3,4.

5,10.3

25,206 =38,559 kA


"K . mFI = "K .5103 ,cb

mFi

U.

S =2,28.5,10.3

25,206 =25,857 kA


HI =H

,cb

XI 510 =

71

5,10

XIcb =

199,0

499,5 =27,633 kA


'0 5NI = "I0 + IH=38,559 + 27,633 = 66,192 kA

"

'5NI =

"I + IH=25,857 + 27,633 = 53,49 kA

Dong ngn mach xung kch tai N5:

kAIKi NxkxkN 497,168192,66.8,1.2..2 "

'0' 55 Giatr hiu dung cua dong ngn mach xung kch tai N5:kAKII xkNxkN 948,99)18,1.(21.192,66)1.(21.

22"

'0' 55


36/77 36


3.2.3.7.1. S bin i:

Tng tnh ngn mach tai N1,s (H:3.9a) i xng nhau qua im ngn machN6 nn ta cos (H:3.4b) vagia tr in khang nh sau:

X17= 0,0587 ; X18= 0,0989 ; X21= 0,0513X19= X20= 0,0733 ; X24= 0,271 ; X22= 0,0288 ;

Ts (H:3.9c), ta co:X73= X22+ X17+ X21= 0,0288 + 0,0587 +0,0513= 0,1388

Ts (H:3.9d), ta co:X74=

1824

1824 .

XXXX

=

0989,0271,0

0989,0.271,0

=0,0725

Ts (H:3.9e), ta co:

352,00725,0

1388,0.0733,01388,00733,0

.

74

7319731975 X

XXXXX

184,01388,0

0725,0.0733,00725,00733,0

.

73

7419741976 X

XXXXX

HT

H:3.9a

E

E E

N6

0587,0

17X

0575,0

14X0575,0

13X

1025,0

9X

1466,0

5X1466,0

8X

1466,0

6X1466,0

7X

1978,01X

1978,0

3X

1978,0

4X1025,0

10X

E

E

HT

H:3.9b

0587,0

17X

0288,0

22X

0513,0

21X

0733,0

20X

0733,0

19X0989,0

18X

1978,0

4X

N6

N6E

E

HT

H:3.9c

1388,0

73X

271,0

24X

0989,0

18X0733,0

19X

E

HT

H:3.9e

N60725,0

75X

0725,0

76X

E

H

H:3.9d

1388,0

73X

0725,0

74X N60733,0

19X


37/77 37



mttX * =X76.cb

mFi

SS =0,184.

100

25,206 =0,38


"K0 =2,6 ;"K =2,05


"K0 . mFI ="K0 .

5103 ,cb

mFi

U.S =2,6.

5,10.3

25,206 =29,486 kA

Dong ngn mach duy tr cac do may phat in cung cp:

"I = "K . mFI = "K .5,10

.3 cb

mFi

US =2,05. 5,10.325,206 =23,249 kA


HI =H

,cb

XI

510 =75

5,10

XIcb =

352,0

499,5 =15,622 kA


'0 6NI = "I0 + IH=29,486 + 15,622 = 45,108 kA

"

'6NI =

"I + IH=23,249 + 15,622 = 38,871 kA

Dong ngn mach xung kch tai N6: kAIKi NxkxkN 826,114108,45.8,1.2..2 "

'0' 66


22"

'0' 66


Theo nguyn tc xp chng ta co:543 NNN

III

Vy, tr sdong ngn mach tai im N3:"

0 3NI = "

0 4NI + "

0 5NI =36,177 + 28,352 = 64,529 kA

"3NI =

"4NI +

"5NI =32,661 + 10,206= 42,867 kA

Dong ngn mach xung kch tai N3:kAiii xkNxkNxkN 675,168583,76092,92543

Giatr hiu dung cua dong ngn mach xung kch tai N3:kAIII xkNxkNxkN 834,100208,46626,54543


38/77 38


Theo nguyn tc xp chng ta co:'557 NNN

III

Vy, tr sdong ngn mach tai im N7:"

0 7NI = "

0 5NI + "

'0 5NI =28,352 +66,192 = 94,544 kA

"

7NI =

"

5NI +

"

'5NI =10,206+53,49 = 63,969 kA

Dong ngn mach xung kch tai N7: kAiii xkNxkNxkN 08,245497,168583,76'557

Giatr hiu dung cua dong ngn mach xung kch tai N7:kAIII xkNxkNxkN 156,146948,99208,46'557

3.2.3.10. im ngn mach N8

Theo nguyn tc xp chng ta co: '668 NNN III Vy, tr sdong ngn mach tai im N8:

"

0 8NI = "

0 6NI + "

'0 6NI =28,352 +45,108 = 73,46 kA

"

7NI = "

6NI +"

'6NI =10,206+38,871= 49,077 kADong ngn mach xung kch tai N8:

kAiii xkNxkNxkN 409,191826,114583,76'668

Giatr hiu dung cua dong ngn mach xung kch tai N8:kAIII xkNxkNxkN 32,114112,68208,46'668

Bang 3.1: BANG KT QUATNH TOAN NGN MACH

PA

im

NM Mach in

Um

(kV)

"

0I

(kA)

"

I

(kA)

ixk

(kA)

Ixk

(kA)

I

N1 Cao ap 220 6,14 5,705 63,15 27,9 N2 Trung ap 110 10,431 8,871 553,26 75,15 N3 Haap MBA 10,5 64,529 42,867 675,168 834,100 N4 Phn oan 10,5 36,177 32,661 092,92 626,54 N4 Phn oan 10,5 25,29 25,857 378,64 187,38 N5 May phat 10,5 28,352 10,206 583,76 208,46 N5 May phat 10,5 66,192 53,49 497,168 948,99 N6 May phat 10,5 28,352 10,206 583,76 208,46 N6 May phat 10,5 45,108 38,871 826,114 112,68 N7 Tdung 10,5 94,544 63,969 08,245 156,146 N8 Tdung 10,5 73,46 49,077 409,191 32,114

3.3. XAC NH XUNG LNG NHIT CUA DONG NGN MACHXung lng nhit dc trng cho lng nhit toa ra trong khi cuin ng vi thi

gian tac ng cua dong ngn mach. Xung lng nhit cua dong ngn mach xac nhtheo biu thc sau:


39/77 39

` BN= dtit

N0

2 . BNCK+ BNKCK

Trong o:- BNCKlaxung lng nhit cua dong ngn mach thanh phn chu ky.

BNCK= 2"NI .ttd

Vi: "NI ladong in ngn mach n nhttdlathi gian tng ng thanh phn chu kycua dong ngn mach

` ttd= f(, t)

Ma: = "

"

0

N

N

II

t lathi gian tn tai ngn mach. Trong tnh toan gn ung cothly t = 0,12 s.

- BNKCKlaxung lng nhit cua dong ngn mach thanh phn khng chu ky.

BNKCK= 2"

0NI .Ta. aTte /2

1 Vi:

Ta lahng sthi gian tng ng cua li in. Khi t 0,1 s th xemaTte /2 0, nn:

BNKCK= 2"0NI .TaVi: U >1000 V th Ta= 0,05 s

3.3.1. Phng an I:Bang 3. 2

imNM

Mach in"

0I kA

"

I kA

ttds

BNCK(kA)2.s

BNKCK(kA)2.s

BN

N1 Cao ap 6,14 5,705 1,076 0,08 2,604 1,885 4,489N2 Trung ap 10,431 8,871 1,176 0,083 6,532 5,440 11,972N3 Haap 64,529 42,867 1,505 0,18 330,764 208,200 538,964N4 Phn oan 36,177 32,661 1,108 0,082 87,473 65,439 152,912N5 May phat 66,192 53,49 1,237 0,085 243,200 219,069 462,269N7 Tdung 94,544 63,969 1,478 0,15 613,805 446,928 1060,733


40/77 40

Chng 4: CHON KH CUIN VATHIT B CODONG INCHAY QUA

4.1. IU KIN CHUNG CHON CAC KH CUIN VACAC PHN TCODONG IN CHAY QUA:

-Chon kiu.

-in ap nh mc.-Dong in lam vic nh mc.

Ngoai ra, ring mi kh cuin con coiu kin ring cua no.Sau khi athoa man cac iu kin chon, chung ta cn kim tra lai n nh in

ng van nh nhit cua cac kh cuin, nu khng thoa man ta phai tnh lai.

4.1.1. Kh cuin:Vic chon loai kh cuin phai phuhp vi iu kin ring cua nonh kh hu, v

tr lp c... ngoai ra ta con cn nhc vmt kythut, kinh tchon cho phuhp.

4.1.2. in ap:in ap nh mc cua cac kh cuin chuyu lado cach in cua noquyt nh.

Cach in cua chung phai chu c khi lam vic lu dai vi in ap nh mc vachuc khi co sc. iu kin:

UmKCUmang.Trong o:

UmKC : in ap nh mc cac kh cuin.Umang : in ap nh mc cua mang ni t kh cuin.

4.1.3. Dong in lam vic:

Cac kh cuin c c chon phai am bao phat nong khi codong in chayqua. am bao iu kin nay th cac kh cuin phai chon theo dong cng bc.

ImKC Imang.i vi thanh dn va cap th codong Icp ladong in lu dai cho phep nn iu

kin la:Icp Ilvcb.

4.1.4. Kim tra n nh nhit:Nhit kh cu in vady dn quacao cothlam cho chung b hong. V vy kh

cuin vady dn c chon phai am bao iu kin n nh nhit , khng vtquatr scho phep.

iu kin kim tra:BN BNtt.

Trong o:BN : Xung lng nhit cua thit b chon, BN= (Inh)2.tnh.BNtt : Xung lng nhit cua dong ngn mach tnh toan.


41/77 41

4.1.5. Kim tra n nh ng:Khi codong ngn mach chay qua cac phn t dn in cua kh cuin th sephat

sinh lc in ng ln selam hong kh cu in nn ta cn kim ta lai n ng.iu kin kim tra:

i ixk.Trong o:

i : Dong n nh ng cua thit b chon.ixk : Dong ngn mach xung kch.

4.2. TNH DONG IN CNG BC:

4.2.1. Phng an I:4.2.1.1.Cac mach pha cao ap 220 kV:

4.2.1.1.1. ng dy lin lac vi hthng:

0985,0220.3.2

044,75

.3.2

max mC

thbt U

SI kA

Trong o:Sth maxlacng sut tha ln nht nhamay phat vhthng.Icb= 2.Ibt= 2.0,0985 = 0,197 kA

4.2.1.1.2. ng dy kep cua phutai:

0463,0220.3.85,0.2

30

.3.cos.2.3.2

maxmax

mCUC

pt

mC

pt

bt UP

US

I kA

Icb= 2.Ibt= 2.0,0463 = 0,0926 kA4.2.1.1.3. Mach cao ap may bin ap lin lac B1, B2:

Dong cng bc c tnh theo khanng quatai cua may bin ap.

63,0220.3200.2,1

3.

mC

mB

sc

qtcb USKI kA

T1, 2, 3 ta suy ra, Icb=0,63 kA c chon lam c scho vic chon kh cuin mach cao ap.

4.2.1.1.4. Thanh gop cp in ap cao:

63,0220.3

200.2,1

.3

.

mC

mBscqt

cb USK

I kA

4.2.1.2.Cac mach pha trung ap 110 kV:

4.2.1.2.1.

ng dy n cua phutai:062,0

110.3.85,0

10

.3.cos.3

maxmax

mTUT

pt

mT

pt

bt UP

US

I kA

4.2.1.2.2. ng dy kep cua phutai:

062,0110.3.2.85,0

20

.3.2.cos.3.2

maxmax

mTUT

Kpt

mT

Kpt

bt UP

US

I kA

Trong o:Sth maxlacng sut ln nht nha may truyn sang pha cao ap.Icb= 2.Ibt= 2.0,062 = 0,124 kA.


42/77 42

4.2.1.2.3. Mach trung ap may bin ap lin lac B1, B2:Dong cng bc c tnh sc mt may bin ap lin lac vaphu tai pha

trung laln nht.

494,0110.3

118,94

.3

max mT

Tcb U

SI kA

T1, 2, 3 ta suy ra, Icb=0,494 kA c chon lam c scho vic chon kh cuin mach trung ap.4.2.1.2.4. Thanh gop cp in ap trung:

26,1110.3

200.2,1

.3

.

mC

mBscqt

cb USK

I kA

4.2.1.3.Cac mach pha haap 10,5 kV:

4.2.1.3.1. Mach haap may bin ap lin lac B1, B2:

492,55,10.3.2

75,199

.3.2

max

mH

Hbt U

SI kA

6,65,10.3

120

.3

1 mH

Bcb U

SI kA

Trong o:1B

S = min { SHmax,1

.. mBclscqt SKK }

1.. mBcl

scqt SKK = 1,2.0,5.200 =120 MVA

SHmax= 199,75 MVA4.2.1.3.2. Mach u cc may phat:

78,35,10.3

75,68

.3

mH

mFbt U

SI kA

Icb= 1,05.Ibt=1,05.3,78 = 3,969 kA4.2.1.3.3. Mach phn oan:

Ibt= btKI = 1,229 kAIcb= cbKI = 2,457 kA

4.2.1.3.4. Mach tdung:

265,05,10.3

75,68%.7

.3

max mH

Ftdbt U

SI i kA

Icb= 1,05.Ibt=1,05.0,265 = 0,278 kA

4.3. CHON MAY CT VADAO CACH LY:

4.3.1. iu kin chon may ct (MC): Loai may ct:

- Vi cp in ap cao vatrung do t ngoai tri nn chon cung mt loai mayct khng kh cho tt cacac mach tn dung kh nen.


43/77 43

- Vi sthit b phn phi trong nha, cp in ap may phat cothchon mt sloai khac nhau.

iu kin chon:- in ap nh mc: UmMCUmmang.- Dong in nh mc: ImMC Icb.- Dong ct nh mc: Icm"

ioNI

Kim tra:- Kim tra n nh ng: I

ixkNI

- Kim tra n nh nhit: I2nh.tnh BN

4.3.2. iu kin chon dao cach ly: iu kin chon:

- in ap nh mc: UmDCLUmmang.

- Dong in nh mc: ImDCL Icb.

Kim tra:- Kim tra n nh ng: IixkN

I - Kim tra n nh nhit: I2nh.tnh BN

Tiu kin chon may ct vadao cach ly cung vi giatr cac dong ngn mach atnh bang 3.1 kt hp vi giatr dong cng bc, cac loai may ct dao cach ly dcchon vi cac thng ssau:


44/77 44

Bang

4.1:LOA

IVA

TH

NGS

MAYC

T

CCHO

N

Thn

gs

cua

mayct

Gia

Inh/

tnh

kA/s

70/10

64/4

70/10

I

kA 175

64 175

Icm

kA 90 63 105

Im A

9000

5600

5000

U

kV 10 10 10

Loaimay

ct

M-10-90

00/1800

M-10-5000-63Y3

M-10-50

00/1800

Thn

gstn

hto

anIxk kA

100,834

54,6

26

99,9

48

I0

kA

64,529

36,177

66,192

Icb kA 6,6

2,457

3,969

Um kV 10

,510,5

10,5

i

mNM

N

3N

4N

5

Mach

in

Haa

p

Phn

oan

Mayp

hat

PA I


45/77 45

Bang

4.2:LOA

IVA

TH

NGS

DAOCAC

HLY

CCHO

N

Thn

gs

cua

daoca

chly

Gia

tnh s 10 10 10

Inh

kA 75 60 65

I kA 25

0200

200

Im A

7000

3000

4000

Um kV 20 10 10

Loai

daoca

chly

PBK-20/7000

PBK-10/3000

PBK-10/4000

Thn

gst

nhto

anIx

kkA

100,834

54,6

26

99,9

48

I0 kA64,5

29

36,1

77

66,1

92

Icb kA 6,6

2,457

3,969

Um kV 10

,510,5

10,5

i

mNM

N

3N

4N

5

Mach

i

nHa

ap

Phno

an

Mayphat

PA I


46/77 46

4.4. CHON THANH GOP, THANH DN, CAP IN LC:Thanh gop, thanh dn, cap in lc, c dung rt nhiu trong cac nhamay in

vatrap bin ap. Thanh dn c dung lam thanh gop, ni cac thit b in vi nhautheo mt s nht nh. Tuy theo nhim vu, v tr t vamt siu kin khac, ngita cothdung thanh dn mm hoc thanh dn cng, thanh dn trn hoc covoboc vihnh dang vakch thc rt khac nhau. Yu cu chung i vi chung ladn in tt, co

bn c hoc vanhit cao, cu tao dn gian... i vi thit b trong nha, giamkch thc cua thit b phn phi, ngi ta dung thanh dn cng. Khi khng coshanchnhiu vkich thc cua thit b phn phi, nht lathit b phn phi in ngoaitri, ngi ta thng dung nhiu cac dy dn mm nhiu si kiu vn xoan bng nghoc nhm loi thep.

4.4.1. Cac mach cp in ap may phat:4.4.1.1.Thanh gop cp in ap may phat:

4.4.1.1.1. iu kin chon:

Ta chon thanh dn cng bng ng, tit din hnh mang. Thanh dn c chontheo iu kin phat nong lu dai cho phep:Icp Icb.

Trong o:Icpladong in cho phep cua thanh dn sau khi aqui i v iu kin lam vic

thc t.Icp= K1.K2.Icp.

Vi:K1 lahshiu chnh theo nhit mi trng, tra sach Thit k phn in

trong nha may in va tram bin ap cua PGS Nguyn Hu Khai, vi nhit mitrng 350C th K1= 0,9.

K2lahshiu ng gn, chon thanh dn cng hnh mang nn K2=0,95.

Icp= K1.K2.IcpIcbIcp21.KK

Icb .

Icp

21.KK

ITGMFcb = 719,795,0.9,0

6,6 kA = 7719 A.

Vy ta chon thanh gop cocac thng ssau:

Kch thc, mmTitdinmtcc,mm2

Mmen trkhang, cm3Mmem quan tnh, cm4Dong chophep cahai

thanh,A

h b c rMt thanh Hai thanh Mt thanh Hai thanh

Wx-x Wy-y Wyo-yo Jx-x Jy-y Jyo-yo

175 80 8 12 2440 122 25 250 1070 114 2190 8550


47/77 47

4.4.1.1.2. Kim tra n nh nhit:

Kim tra n nh nhit theo iu kin tit din cho phep:

Schon Smin=C

BN .

Trong o:Schonlatit din dy dn cn kim tra n nh nhit.Sminlatit din nhonht mathanh dn coth chu ng c khi xay ra ngn

ngn mach trn thanh dn.

C lahsphuthuc vao vt liu lam thanh dn, ta chon thanh dn lam bng vtliu ng nn C = 171 A2.s/mm2

Smin= 46,19010.171

1060,733 37 CBN mm2.

Schon= 2.2440 = 4880mm2> 190,46 mm2.Vy thanh dn achon thoa man iu kin n nh nhit.

4.4.1.1.3. Kim tra n nh ng:

Kim ta n nh ng bng phng phap n gian hoa. Theo phng phap nay, tacoi mi nhp thanh dn (phn thanh dn gia hai sgn nht) cochiu dai

1 lamtdm tnh, khi ngn mach thanh dn chu tac ng cua mt lc khng i F1vabng lccc ai khi ngn mach ba pha tnh vi pha gia. Mi thanh dn hnh mang gm haithanh hnh chU ghep lai vi nhau, nn ng sut trong thanh dn gm hai phn 1 va

2 . Ta co:

tt = 1 + 2 (kG/cm2)Trong o:

1 lang sut do dong in gia cac pha tac ng vi nhau sinh ra.

2 la ng sut do dong in trong hai thanh dn cung pha tac ng vi nhau

sinh ra.


48/77 48

-Xac nh 1 :

Lc in ng gia cac pha sinh ra:

F1= 1,8.10-2.a

1 . 2)3(xki

Trong o:)3(

xki ladong in xung kch khi ngn mach ba pha (tai im N7), kA.

a lakhoang cach gia cac thanh dn, chon a = 40 cm.1 lachiu dai cua mt nhp thanh dn, chon 1 = 100 cm.

F1= 1,8.10-2.40

100 . 2245,08 = 2702,89 kG.

Mmem un cua thanh dn khi snhp ln hn hai:

M1=10

. 11F =10

.1002702,89 = 27028,9 kG.cm.

Mmen chng un cua thanh dn:W1= Wyo-yo=250 cm3

ng sut trong thanh dn 1 di tac dung cua mmen un M1:1

=1

1

WM =

250

27028,9 = 108,116 kG/cm2

-Xac nh 2 :

Lc tac ng trn mt n v chiu dai cua thanh dn (1 cm)

f2=0,51.10-2.h1 . 2)3(xki

Trong o:

h lachiu cao thanh dn, h = 175 mm =17,5 cm f2= 0,51.10-2.

5,17

1 . 2245,08 = 17,504 kG/cm.

giam ng sut trn thanh dn ngi ta dt thm cac ming m cach nhau mtkhoang

2 trong khoang gia hai s lin nhau cua mt pha. Lc tac ng ln oanthanh dn gia hai ming slin tip cochiu dai 2 :

F2= f2. 2 Mmen un tac ng ln thanh dn:

M2= 12.

22

F= 12

. 2

22

fkG.cm.

Mmen chng un cua tit din ngang thanh dn:W2= Wy-y= 25 cm3

ng sut trong vt liu dy dn do f2sinh ra:

2 =

2

2

WM =

2

2

22

.12

.

Wf kG/cm2

-iu kin n nh ng cua thanh dn:

tt = 1 + 2 cp


49/77 49

Trong o:

cp lang sut cho phep cua vt liu lam thanh dn, i vi thanh dn ng

cp = 1400 KG/cm2

2 cp - 1

2

2

22

.12

.

Wf cp - 1 2

2

21 .12).(

fWcp

= max2

max2 =

504,17

25.12).108,1161400( = 148,8 cm

Ta thymax2 = 148,8 cm > 1 = 100 cm

Do okhng cn t thm ming m vao gia hai smavn am bao iu kinn nh ng.

4.4.1.1.4. Kim tra n nh ng cua thanh dn khi coxet n dao ng:

Tn scua thanh dn cohnh dang bc kyc xac nh nh sau:

.S.J.E.,fr

6

2

10563

Hz.

Trong o:lachiu dai cua mt nhp thanh dn.E lamodul an hi cua vt liu lam thanh dn, thanh dn ng:

E =1,1.102kG/cm2.J lammen quatnh cua thanh dn i vi truc thng goc vi phng un

J = Jyo-yo= 2190 cm4. lakhi lng ring cua vt liu lam thanh dn

cu

= 8,93 g/cm2.S latit din ngang cua thanh dn, s = 2.2440 = 4880 mm2= 48,8 cm2.

837938848

1021901011

100

563 66

2

,.,...,.,fr Hz.

Ta thy, tn sdao ng fr= 837 Hz nm ngoai khoang (45 - 55) Hz va(90 - 110)nn iu kin n nh ng khi coxet n dao ng ring c thoa man.

Vy: Thanh gop a chon thoa man cac iu kin kim tra.4.4.1.2.Thanh dn tu cc may phat n thanh gop cp in ap may phat:

4.4.1.2.1. iu kin chon:

Ta chon thanh dn cng bng ng, tit din hnh mang. Thanh dn c chontheo iu kin phat nong lu dai cho phep:

Icp21.KK

Icb .

Icp21.KK

IMFcb = 642,495,0.9,0

969,3 kA = 4642 A.


50/77 50




thanh,Ah b c r

Mt thanh Hai thanh Mt thanh Hai thanh


125 55 6,5 10 1370 50 9,5 100 290,3 36,7 625 5500

4.4.1.2.2. Kim tra n nh nhit:


Schon Smin=CBN

.

Smin= 73,12510.171

462,269 3'5 CBN mm2.

Schon= 2.1370 = 2740mm2> 125,73mm2.Vy thanh dn achon thoa man iu kin n nh nhit.


Mi thanh dn hnh mang gm hai thanh hnh chU ghep lai vi nhau, nn ngsut trong thanh dn gm hai phn 1 va 2 . Ta co:

tt = 1 + 2 (kG/cm2)-Xac nh 1 :

Lc in ng gia cac pha sinh ra:F1= 1,8.10-2.

a1 . 2)3(xki

Trong o:)3(

xki ladong in xung kch khi ngn mach ba pha (tai im N5), kA.a lakhoang cach gia cac thanh dn, chon a = 40 cm.

1 lachiu dai cua mt nhp thanh dn, chon 1 = 100 cm.

F1= 1,8.10-2.40

100 . 2168,479 = 1135,407 kG.

Mmem un cua thanh dn khi snhp ln hn hai:M1=

10

. 11F =10

.1001135,407 = 11354,07 kG.cm.

Mmen chng un cua thanh dn:W1= Wyo-yo=100 cm3

ng sut trong thanh dn 1 di tac dung cua mmen un M1:

1 =

1

1

WM =

100

11354,07 = 113,54 kG/cm2.


51/77 51

-Xac nh 2 :


f2=0,51.10-2.h1 . 2)3(xki

Trong o:

H lachiu cao thanh dn, h = 125 mm =12,5 cm. f2= 0,51.10-2.

5,12

1 . 2168,479 = 11,581 kG/cm.

Lc tac ng ln oan thanh dn gia hai ming slin tip cochiu dai2 :

F2= f2. 2 Mmem un tac ng ln thanh dn:

M2=12

. 22 F =12

. 2

22 f kG.cm.

Mmen chng un cua tit din ngang thanh dn:

W2= Wy-y= 9,5 cm3ng sut trong vt liu dy dn do f2sinh ra:

2 =2

2

WM =

2

2

22

.12

.

Wf kG/cm2


tt = 1 + 2 cp 2 cp - 1

2

2

22

.12

.

W

f cp - 1 2 2

21 .12).(

f

Wcp = max2

max2 =11,581

5,9.12).113,541400( = 112,53 cm

Ta thy max2 = 112,53 cm > 1 = 100 cmDo okhng cn t thm ming m vao gia hai smavn am bao iu kin

n nh ng.4.4.1.2.4. Kim tra n nh ng cua thanh dn khi coxet n dao ng:


.S.J.E.,fr6

2 10563 Hz.

Vi:E =1,1.102kG/cm2.J = Jyo-yo= 2190 cm4.

cu = 8,93 g/cm2.S = 2.1370 = 2740 mm2= 27,4 cm2.


52/77 52

7596938427

106251011

100

563 66

2,

,.,...,.,fr Hz.

Ta thy, tn sdao ng fr= 596,7 Hz nm ngoai khoang (45 - 55) Hz va(90 -110) nn iu kin n nh ng khi coxet n dao ng ring c thoa man.

Vy: Thanh dn achon thoa man cac iu kin kim tra.

4.4.1.3.

Thanh dn tthanh gop cp in ap may phat n haap may bin ap:

4.4.1.3.1. oan trong nha:

Tng tkhi chon thanh gop cp in ap may phat:a. iu kin chon:

Ta chon thanh dn cng bng ng, tit din hnh mang. Thanh dn c chontheo iu kin phat nong lu dai cho phep:

Icp21.KK

Icb .

Icp21.KK

IMBAcb = 719,7

95,0.9,06,6 kA = 7719 A




thanh,A

h b c rMt thanh Hai thanh Mt thanh Hai thanh


175 80 8 12 2440 122 25 250 1070 114 2190 8550

b. Kim tra n nh nhit:


Schon Smin=CBN .

Smin= 764,13510.171

538,964 33 CBN

mm2.

Schon= 2.2440 = 4880mm

2

> 135,764 mm2

.Vy thanh dn achon thoa man iu kin n nh nhit.c. Kim tra n nh ng:

Mi thanh dn hnh mang gm hai thanh hnh chU ghep lai vi nhau, nn ngsut trong thanh dn gm hai phn

1 va

2 . Ta co:

tt = 1 + 2 (kG/cm2)


53/77 53

-Xac nh 1 :

Lc in ng gia cac pha sinh ra:

F1= 1,8.10-2.a

1 . 2)3(xki

Trong o:)3(

xki ladong in xung kch khi ngn mach ba pha (tai im N3), kA.a lakhoang cach gia cac thanh dn, chon a = 40 cm.1 lachiu dai cua mt nhp thanh dn, chon 1 = 100 cm.

F1= 1,8.10-2.40

100 . 2168,675 = 1280,3 kG.

Mmem un cua thanh dn khi snhp ln hn hai:

M1=10

. 11F =10

.1001280,3 = 12803 kG.cm.

Mmen chng un cua thanh dn:

W1= Wyo-yo=100 cm3

ng sut trong thanh dn 1 di tac dung cua mmen un M1:

1 =1

1

WM =

100

12803 = 128,03 kG/cm2.

-Xac nh 2 :


f2=0,51.10-2.h1 . 2)3(xki

Trong o:

H lachiu cao thanh dn, h = 175 mm =17,5 cm.f2= 0,51.10-2.

5,17

1 . 2168,675 = 8,292 kG/cm.

Lc tac ng ln oan thanh dn gia hai ming slin tip cochiu dai 2 :F2= f2. 2

Mmem un tac ng ln thanh dn:

M2=12

. 22 F =12

. 2

22 f kG.cm.

Mmen chng un cua tit din ngang thanh dn:

W2= Wy-y= 25 cm3ng sut trong vt liu dy dn do f2 sinh ra:

2 =

2

2

WM =

2

2

22

.12

.

Wf kG/cm2.


tt = 1 + 2 cp


54/77 54

2

cp - 1

2

2

22

.12

.

Wf cp - 1 2

2

21 .12).(

fWcp

= max2

max2 =8,292

25.12).128,031400( = 204,52 cm

Ta thymax2

= 204,52 cm >1

= 100 cmDo okhng cn t thm ming m vao gia hai smavn am bao iu kin

n nh ng.d. Kim tra n nh ng cua thanh dn khi coxet n dao ng:


.S.J.E.,fr

6

2

10563

Hz.

Vi:E =1,1.102kG/cm2.

J = Jyo-yo= 2190 cm4.cu = 8,93 g/cm2.

s = 2.2440 = 4880 mm2= 48,8 cm2.

837938848

1021901011

100

563 66

2

,.,...,.,fr Hz.

Ta thy, tn sdao ng fr= 837 Hz nm ngoai khoang (45 - 55) Hz va(90 - 110)nn iu kin n nh ng khi coxet n dao ng ring c thoa man.

Vy: Thanh dn achon thoa man cac iu kin kim tra.

4.4.1.3.2.

oan ngoai tri:a. iu kin chon:

Ta chon dy dn mm theo iu kin phat nong lu dai cho phep:

Icp21.KK

Icb .

Icp21

.KKIMBAcb = 33,7

1.9,0

6,6 kA = 7330 A

Ta chon mt body dn gm 7 dy AC-700/86 coIcp= 71220 = 8540 A ; d =36,2 mm.

b. Kim tra n nh nhit khi ngn mach:


Schon Smin=CBN .

Smin= 814,23610.88

538,964 33 CBN

mm2.

Schon= 700 mm2> 236,814 mm2.


55/77 55

Vy thanh dn achon thoa man iu kin n nh nhit.4.4.1.4.Chon cap cho phutai a phng:

y ta ch chon mt phn cap dn tthanh gop cp in ap may phat ra ngoainhamay (khoang 200 m). Ta chon cap cach in bng giy, loi ng.

4.4.1.4.1. iu kin chon:Tit din cua dy dn c chon theo mt dong in lam vic kinh t:

kt

btkt JIS .

Trong o:Ibtladong in lam vic bnh thng cua mach in.Jktlamt dong in kinh t, phuthuc vao Tmax.

Tmax=max

max.

PtP ii =

max

max.

StS ii = 56.480.864.672.6.

80

365 = 7665 h.

Tra sach Thit k phn in trong nha may in va tram bin ap cua PGSNguyn Hu Khai, i vi cap cach in bng giy, loi ng th Jkt= 2 A/cm2.

a. i vi ng dy kep:661,343

8,0.5,10.3.2

10.10

cos..3.2.3.2

3

m

K

m

KKbt U

PU

SI A.

831712

661343Skt ,

,JI

kt

KbtK mm2.

b. i vi ng dy n:

393,4128,0.5,10.3

10.6

cos..3.3

3

m

m

bt U

PU

SI A.

22062

393412

Skt ,

,

J

Ikt

bt

mm2

.Theo kinh nghim th khi Skt150 mm2th scap kinh tc xac nh bi:

146,1150

83,171

150

KktK

btSn .

3751150

2206

150,,Sn

kt

bt .

Vy i vi ng dy kep, chon 2 si cap ng lam vic song song; i ving dy n ta cung chon 2 si cap ng lam vic song song. Tra sach Thit k

phn in trong nhamay in vatram bin ap cua PGS Nguyn Hu Khai, cap ngtit din 150 mm2coIcp= 355 A.

4.4.1.4.2. Kim tra cap theo iu kin phat nong lu dai:

a. Kim tra iu kin phat nong cua cap khi lam vic bnh thng:

Icp= K1.K2.IcpIbt.Trong o:

Icpladong in cho phep cua thanh dn sau khi aqui i v iu kin lam victhc t.


56/77 56

K1lahshiu chnh theo nhit mi trng, chon K1= 1K2lahshiu chnh theo scap t song song vi nhau; vi khoang cach 300

mm nu 2 si cap th K2= 0,93.-i vi ng dy kep:

661343,IKbt AIcp= K1.K2.Icp= 1.0,93.2.355 = 660,3 661343,IKbt A.

-i vi ng dy n:393412,Ibt A

Icp= K1.K2.Icp= 1.0,93.2.355 = 660,3 393412,Ibt A.Vy cap achon thoa man iu kin phat nong khi lam vic bnh thng.

b. Kim tra iu kin phat nong cua cap khi lam vic cng bc:

Ta ch kim tra ng dy kep v khi scng dy n th ng dy n semt in nh sau:

scqtK .IcpIcb.

Trong o:scqtK la h smang tai cho phep cua cap khi s c, c xac nh theo h s

mang tai luc bnh thng cua cap Kbt= 'cp

bt

II .100 nh sau:

scqtK = 1,3 nu Kbt80%

scqtK = 1,0 nu Kbt>80%

Hsmang tai luc bnh thng cua cap:

Kbt= 'cp

Kbt

II .100 =

3660

661343

,, .100 = 52%

Do o: scqtK = 1,3.

scqtK .Icp= 1,3.660,3 = 858,39 A > Icb= 2.343,661 = 687,322 A.Vy cap achon thoa man iu kin phat nong khi lam vic cng bc.

c. Kim tra iu kin n nh nhit cua cap:

iu kin nay sec kim tra sau khi chon khang in ng dy.4.5. CHON S:

Slakh cuin dung gicac dy dn trn. Do vy, sphai chu c in apln nht cotht ln dy dn, phai chu dng c tac ng c hoc vanhit hoc cuadong in khi lam vic lu dai cung nh khi ngn mach, ng thi phai chu c tacng cua mi trng lam vic.

4.5.1. Chon scho cac thanh dn cng:Sc chon theo cac iu kin sau:-Loai s: Sc t trong nhahay ngoai tri.


57/77 57

-in ap: UmsUmHT.-Kim tra iu kin n nh ng:

FttFcp= 0,6.Fph.Trong o:

Fcp lalc cho phep tac dung ln u s, kG.Fph lalc phahoai nh mc cua s, kG.

Ftt

lalc tnh toan ng tr qui i vu s, kG.

H

hH.F

H'H.FFtt

2

11

Vi: F1lalc tnh toan trn khoang vt thanh dn, kG.H lachiu cao cua trong tm thanh dn.H lachiu cao cua s.h lachiu cao thanh dn.

4.5.1.1.Sthanh gop cp in ap may phat.

Ta co: F1= 2702,89 KG.h = 175 mm.Chon scocac thng ssau:

Loai sin ap, kV Lc phahoai

nhonht khiun tnh, kG

Chiu cao,mmnh mc

Duy tr trang thai kh

OP- 10 - 6000Y3 10 47 6000 300

Vy:

2333491300

2

175300

892702 ,.,Ftt

kG.

Fcp= 0,6Fph= 0,6.6000 = 3600 kG.Ta thy Ftt< Fcp. Vy sachon thoa man yu cu n nh ng.

4.5.1.2.Sthanh dn tu cc may phat n thanh gop 10,5 KV:

Ta co: F1= 1135,407 KG.h = 125 mm.

Chon scocac thng ssau:



Chiu cao,mmnh mc


OP- 10 - 3000Y3 10 47 3000 150


58/77 58

Vy:

51608150

2

125150

1135,407 ,.Ftt

kG.


4.5.1.3.

Sthanh dn tthanh gop cp in ap may phat n may bin ap linlac (phn trong nha):

Ta co: F1= 1280,3 KG.h = 175 mm.

Chon scocac thng ssau:



Chiu cao,mmnh mc


OP- 10 - 3000Y3 10 47 3000 300

Vy:

7211653300

2

175300

1280,3 ,.Ftt

kG.


4.5.2. Chon sxuyn tng:Vi sxuyn khi chon ta da vao cac iu kin:-in ap UmSUmg-Dong in ImSIlvcbTa co: Umg= 10,5 kV.

MBAlvcbI = 6,6 kA.

Vy ta chon sxuyn cho thanh dn loai:TA-10 Co UmS= 10,5 kV; Ims= 8000 A; Fph= 6000 kG.

4.6. CHON KHANG IN NG DY:Khang in ng dy cotac dung han chdong ngn mach hoc dong in khi

ng cua ng c trong cac mach cng sut ln nhm chon c kh cuin hang nhevanng cao in ap d trn thanh gop khi ngn mach trn ng dy.

4.6.1. iu kin chon vakim tra:i vi khang in ng dy khi chon ta da vao cac iu kin:-in ap : UmKUmg


59/77 59

-Dong in : ImKIlvcp-Kim tra U% khi lam vic bnh thng vacng bc.-Kim tra iu kin n nh ng: iixk.-Kim tra iu kin n nh nhit: 2nhI .tnhBN.

4.6.2. Lp bang phn bcng sut qua khang:

Trang thai K5, MW K6, MW K7, MW K8, MWBnh thng 10 22 10 22

ScK1 0 32 10 22ScK2 20 0 10 22ScK3 10 22 0 32ScK4 10 22 20 0

Dong in lam vic bnh thng qua khang:

687,08,0.5,10.3

10

cos..3.3

55

75

m

K

btm

K

btKbt

Kbt U

PU

SII kA.

512,18,0.5,10.3

22

cos..3.3

66

86

m

Kbt

m

KbtK

btKbt U

PU

SII kA.

Dong in cng bc qua khang:

375,18,0.5,10.3

20

cos..3.3

55

75

m

Kcb

m

KcbK

cbKcb U

PU

SII kA.

199,28,0.5,10.3

32

cos..3.3

66

86

m

Kbt

m

KbtK

btKbt U

PU

SII kA.

Tra sach Thit k phn in trong nha may in va tram bin ap cua PGSNguyn Hu Khai:

-Ta chon khang in K1, K3laPbA - 10 - 1500 - XK%.-Ta chon khang in K2, K4laPbA - 10 - 2500 - XK%.

4.6.3. Xac nh XK%:XK% c xac nh theo iu kin han chdong ngn mach n tr scho phep

nhm am bao n nh ng, n nh nhit vakhanng ct cua may ct sau khang


60/77 60

in ng dy va am bao in ap d trn thanh gop phn oan. ng thi phai baoam tn tht in ap trn khang in khng c vt quatr scho phep.4.6.3.1.Xac nh %

5KX , %

7KX :

Xet khang in K5(K7) ta cos ngn mach nh sau:

Ts , ta co:

tt

,cb"N X

II 5100 10 . (5.1)

Vi:

Xtt= XH+ XK.0580

94,544

4995

70

510 ,,II

X "N

,cbH .

am bao khanng ct cua may ct a phng vaiu kin n nh nhit chocap:

"NI 100 = min {Icm, InhC}

Trong o:

Icmladong in ct nh mc cua may ct a phng, Icm= 20 kA.InhCladong in n nh nhit cua cap a phng.

InhC=ct

C.S .

Vi: S latit din cua cap.C lahsphuthut vao vt liu lam cap, Ccu= 141 As1/2/mm2.Tclathi gian ct ngn mach cua may ct, tc= 1 s.

InhC= 3101

141150 .. = 21,15 kA > 20 kA.

Vy: "NI 100 = 20 kA.

T(5.1)Xtt="

010

5,10

IIcb =

20

4995, = 0,275.

XK=Xtt- XH= 0,275 - 0,058 = 0,217.

%X K1 = %XK3 = XK.510,cb

m

II .100=0,217.

4995

51

,, .100 = 5,92 %.

Vy ta chon %5K

X = %7K

X = 6%.


61/77 61

4.6.3.2.Xac nh %6K

X , %8K

X :

Xet khang in K6(K8) ta cos ngn mach nh sau:

Ts , ta co:

tt

cbN X

II 5,10"0 11 . (5.1)

Vi:Xtt= XH+ XK.

0749,073,46

499,5"

0

5,10

8

N

cbH I

IX .

am bao khanng ct cua may ct a phng vaiu kin n nh nhit chocap:

"

0 11NI = min {Icm, InhC} = 20 kA.

T(5.1)Xtt="

011

5,10

IIcb =

20

499,5 = 0,275.

XK=Xtt- XH= 0,275 - 0,0749 = 0,2.

%XK 2 = %XK 4 = XK.5,10cb

m

II .100=0,2. 499,55,2 .100 = 9,1 %.

Vy ta chon khang K5, K7lakhang in n vachon K6, K8lakhang in kep.


62/77 62

*Phn blai cng sut qua khang:

Trang thai K5, MWK6, MW K7, MW

K8, MWNh1 Nh2 Nh1 Nh2

Bnh thng 10 11 11 10 11 11ScK1 0 16 16 10 11 11ScK2 20 0 0 10 11 11ScK3 10 11 11 0 16 16ScK4 10 11 11 20 0 0

Dong in lam vic bnh thng qua khang:

687,08,0.5,10.3

10

cos..3.3

55

75

m

Kbt

m

KbtK

btKbt U

PU

SII kA.

756,0

8,0.5,10.3

11

cos..3.3

66

8866 2121

m

Kbt

m

KbtKNh

btKNh

btKNh

btKNh

bt

U

P

U

SIIII kA.

Dong in cng bc qua khang:

375,18,0.5,10.3

20

cos..3.3

57

75

m

Kcb

m

KcbK

cbKcb U

PU

SII kA.

1,18,0.5,10.3

16

cos..3.3

66

8866 2121

m

Kbt

m

KbtKNh

cbKNh

cbKNh

cbKNh

cb UP

USIIII kA.

Tra sach Thit k phn in trong nha may in va tram bin ap cua PGS

Nguyn Hu Khai:-Ta chon khang in K5, K7laPbA - 10 - 1500 - XK%.-Ta chon khang in K6, K8laPbA - 10 - 21500 - XK%.*Xac nh %

5KX , %

7KX :

XK= 0,217.

%5K

X = %7K

X = XK.510,cb

m

II .100=0,217.

4995

51

,, .100 = 5,92 %.


63/77 63

Vy ta chon %5K

X = %7K

X = 6%.

Loai khang in Um, kV Im, A XK% PK, kW I, kA In, kAPbA - 10 - 1500 - 6% 10 1500 6 10,5 53 42

*Xac nh %6K

X , %8K

X :

XK= 0,2.

%6K

X = %8K

X = XK.510,cb

m

II .100=0,2.

499,5

5,1 .100 = 5,46%.

Vy ta chon %6K

X = %8K

X = 6%.

Loai khang in Um, kV Im, A HsK PK, kW I, kA In, kAPbAC - 10 - 21500 - 6 10 1500 0,62 20,6 53 42

4.6.3.3.Kim tra khang in achon:

4.6.3.3.1.

Kim khanng ct cua may ct a phng van nh nhit:Ta co:

5KX =

7KX = XK%.

mK

cb

II

5,10 = 6%.5,1

499,5 = 0,22.

78,1922,0058,0

499,55,10"0 10

KH

cbN XX

II kA.

6KX =

8KX = XK%.

mK

cb

II

5,10 = 6%.5,1

499,5 = 0,22.

65,1822,00749,0499,55,10"

0 11 KH

cbN XX

II kA.

Ta thy, "0 10N

I va"0 11N

I Icm, InhC.

Vy khang in achon thoa iu kin nay.4.6.3.3.2. Kim tra iu kin tn tht in ap UK%:

a. iu kin lam vic bnh thng: %2%% cpKbt UU

- Khang in n K5, K7:

2%%65,16,0.5,1

687,0%.6sin%.%%

5

5

5

75

mK

Kbt

KKbt

Kbt I

IXUU .

- Khang in kep K6, K8:

Vy %2%% cpKbt UU thoa man.

86 %% KbtKbt UU

2%%67,06,0.5,1

756,0.62,0756,0%.6

sin.

%.

6

66

6

21

mK

KNhbt

KNhbt

K IIKI

X


64/77 64

a. iu kin lam vic cng bc: %5%% cpKcb UU


5%%3,36,0.5,1

375,1%.6sin%.%%

5

5

5

75 mK

Kcb

KKcb

Kcb I

IXUU .


Vy %5%% cpKcb UU thoa man.

4.6.3.3.3. Kim tra iu kin tao in ap d trn thanh gop khi ngnmach sau may ct ng dy:


60%%12,795,178,19%.6%.%%

5

10

51

75

"

0 mK

NK

Kd

Kd I

IXUU .


60%%6,745,1

65,18%.6%.%%

6

11

6

86

"

0 mK

NK

Kd

Kd I

IXUU

Vy khang in dachon thoa man iu kin nay.


ixk i.- Khang in n K5, K7:

i= 53 kA.ixk= 35,5078,19.8,1.2..2

"

0 10Nxk IK kA < i.

- Khang in kep K6, K8:i= 53 kA.ixk= 48,4765,18.8,1.2..2

"

0 11Nxk IK kA < i.

Vy khang in dachon thoa man iu kin n nh ng.4.6.3.3.5. Kim tra n nh nhit:

V cac khang in achon coIm> 1000 A nn khng cn kim tra iu kin nnh nhit.

Vy khang in K5, K6, K7, K8achon thoa man tt cacac iu kin kim tra.

86 %% KcbKcb UU

5%%16,0.5,1

1,1.62,01,1%.6

sin.%.

6

66

6

21

mK

KNh

cb

KNh

cbK I IKIX


65/77 65

4.6.4. Kim tra n nh nhit cho cap phutai cp in ap may phat 10,5 kv:4.6.4.1.i vi ng dy ni vi khang in n K5, K7:

Chiu dai cua oan cap la200 m.in khang cua oan cap la:

2

5,10

...1

cb

cbOC U

SXn

X .

Trong o:XOlain khang trn 1 n v chiu dai, chon cap cotit din S = 150 mm2, U

= 10,5 kV Tra sach Thit kcac mang vahthng in cua Nguyn Vn am (trang262) th XO= 0,079/km.

n lassi cap lam vic song, n = 2.lachiu dai cap, = 200 m = 0,2 km.

0072,05,10

100.2,0.079,0.

2

12KCX .

Dong ngn mach tai cui oan cap:

28,190072,022,0058,0

499,55,10"

KCKH

cbN XXX

II kA.

Xung lng nhit tnh toan cua cap:BNtt= 2"NI (t + Ta) = 19,282(1 + 0,05) = 390,3 (kA)2s.

Tit din nhonht macap cothchu c khi cap xay ra ngn mach:

1,14010.141

3,390 3min

CB

S Ntt mm2.

Vy cap achon thoa man iu kin n nh nhit.

4.6.4.2.i vi ng dy ni vi khang in kep K6, K8:

Chiu dai cua oan cap la200 m.in khang cua oan cap la:

2

5,10

...1

cb

cbOC U

SXn

X .

Trong o:XOlain khang trn 1 n v chiu dai, chon cap cotit din S = 150 mm2, U

= 10,5 kV Tra sach Thit kcac mang vahthng in cua Nguyn Vn am (trang

262) th XO= 0,079/km.n lassi cap lam vic song, n = 2.lachiu dai cap, = 200 m = 0,2 km.

0072,05,10

100.2,0.079,0.

2

12CX .

Dong ngn mach tai cui oan cap:

2,180072,022,00749,0

499,55,10"

KCKH

cbN XXX

II kA.

Xung lng nhit tnh toan cua cap:


66/77 66

BNtt= 2"NI (t + Ta) = 18,22(1 + 0,05) = 347,8 (kA)2s.Tit din nhonht macap cothchu c khi cap xay ra ngn mach:

27,13210.141

347,8 3min

CB

S Ntt mm2.

Vy cap achon thoa man iu kin n nh nhit.

4.6.5. Chon may ct sau khang in ng dy:4.6.5.1.iu kin chon may ct:

-Loai may cat in.-in ap : UmMCUmg.-Dong in : ImMCIlvcb.-iu kin ct : Icm MC"0NI .-Kim tra iu kin n nh ng: iixk.-Kim tra iu kin n nh nhit: 2nhI .tnhBN.

4.6.5.2.i vi ng dy ni vi khang in n K5, K7:

Dong in lam vic cng bc la:5K

cbI = 1,375 kA.Tra sach Thit k phn in trong nha may in va tram bin ap cua PGS

Nguyn Hu Khai, ta chon may ct in co cac thng snh bang sau:

Loai may ct in Um, kV Im, A Icm, kA i, kA In/tnh, kA/sBM -10-1600-20 10 1600 20 52 20/4

4.6.5.3.i vi ng dy ni vi khang in kep K6, K8:

Dong in lam vic cng bc la: 6KcbI = 1,1 kA.Tra sach Thit k phn in trong nha may in va tram bin ap cua PGS

Nguyn Hu Khai, ta chon may ct in co cac thng snh bang sau:

Loai may ct in Um, kV Im, A Icm, kA i, kA In/tnh, kA/sBM -10-1250-20K 10 1250 20 64 20/8

4.6.5.4.

Kim tra may cat achon:


iixk.- i vi ng dy ni vi khang in n K1, K3:

i= 52 kA.ixk= 35,5078,19.8,1.2..2

"

0 10Nxk IK kA < i.

- i vi ng dy ni vi khang in kep K2, K4:i= 64 kA.


67/77 67

ixk= 48,4765,18.8,1.2..2 "

0 11Nxk IK kA < i.

Vy may ct achon thoa man iu kin n nh ng.4.6.5.4.2. Kim tra n nh nhit:

V cac may ct achon coIm> 1000 A nn khng cn kim tra iu kin n nhnhit.

4.7. CHON CUN DP HQUANG:Nhamay in cocp in ap may phat U = 10,5 kV lamang trung tnh canh ini vi t ch cho phep lam vic khi cocham t mt pha trong mang nu dong indung khng vt quatr scho phep (30 A i vi mang 10 kV, 10 A i vi mang35 kV), khi dong in dung ln hn, ngi ta thng dung cun dp hquang nivao im trung tnh cua mang cach t.

4.7.1. iu kin chon:Cun dp hquang c chon theo iu kin sau:

UmUph.

Q Qtt= n.Ic.Uph.Trong o:

Uphlain ap pha cua mang, kV.

n lahstnh dn sphat trin cua mang chon bng 1,25.ICladong in cham t mt pha va c xac nh thu cng thc kinh nghim

sau:- i vi ng dy trn khng:

Ic=350

. dU [A].

- i vi ng dy cap:

Ic=10

. dU [A].

Vi latng chiu dai cua ng dy.

4.7.2. Chon cun dp hquang cho mang cp in ap may phat 10,5 kV:Phutai cp in ap may phat gm:

- 4 ng dy kep x 10 MVA dai 13 km.- 4 ng dy n x 6 MVA dai 12 km.

Tng chiu dai ng dy: = 4.2.13 + 4.12 = 152 km.

Tng chiu dai cap: = 4.2.0,2 + 4.0,2 = 2,4 km.

Tng chiu dai ng dy trn khng:K = - = 152 - 2,4 = 149,6 km.

Dong dung dn cua n dy trn khng:


68/77 68

KcI =

350

. KdU =350

6,149.5,10 = 4,488 A.

Dong dung dn cua cap:CcI =

10

. CdU =10

4,2.5,10 = 2,52 A.

Dong dung dn cua ng dy phutai cp in ap may phat:

Ic=K

cI +C

cI = 4,488 + 2,52 = 7,008 A.Ta thy, Ic< 30A nn khng cn phai chon cun dy hquang mang 10,5 kV.

4.8. CHON MAY BIN DONG, MAY BIN IN AP:Cac phn ttrong hthng in thng coin ap cao vadong in lam vic ln,

khng tha trc tip cac ai lng nay vao cac dung cuo lng, cac rle, cac thitb tng ng hoa vakim tra. cung cp tn hiu cho cac thit b trn, ngi ta dungcac may bin dong in (BI) vacac may bin in ap (BU), goi chung lamay bin apo lng.

May bin dong in (BI) lacac may bin ap o lng, lam nhin vu bin i dong

in ln cn o I1xung dong in tiu chun I2vi tn hao vasai snho cung cpcho cac dung cuo lng, bao vrle vatng hoa trong hthng mt cach an toan.

May bin in ap (BU) lamay bin ap o lng dung bin i in ap tmt trsnao oU1(thng U1380 V) vmt tr sthch hp U2(100; 100/ 3 va100/3V) cung cp cho cac dung cu o lng, bao v rle, t ng hoa, kim tra cachin... trong mang in.

Ngoai ra nhcomay bin ap, may bin dong macac dung cuo lng, cac rlec cach ly vi mang in cao U1, am bao an toan cho nhn vin vn hanh.

y ta chon BI, BU cho mang may phat Um= 10,5 kV,MFcbI = 3,969 kA.

4.8.1. Chon may bin dong (BI):4.8.1.1.iu kin chon:

May bin dong BI c chon theo cac iu kin:-in ap : UmBIUmg=10,5 kV.

-Dong in : ImBI2,1

cbI = 308,32,1

969,3 kA.

-Phutai : Z2m BIZ2 = r2.-n nh ng : m IK 1..2 ixk.

-n nh nhit : 2

1. mnh Ik

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