Thiet Ke TBA 220KV

7/28/2019 Thiet Ke TBA 220KV

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TONG QUAN CHNG 1

SVTH: TRN ANH TRUNG GVHD: L NH LNG4

LI CM N

Em chn thnh cm n Thy L nh Lng trc tip hng dn, cung cp

ti liu v to mi iu kin em hon thnh n mn hc ny.

Em cng xin gi li cm n n Thy- Trn Thanh Sn cng cc thy c trong

khoa in-in t ging dy, truyn t v trang b kin thc cho em trong sut

thi gian em hc Trng i Hc K Thut Cng Ngh Thnh Ph H Ch Minh

hon thnh n mn hc ny.

Trong qu trnh lm n mn hc, do thi gian hn ch nn ti em hon

thnh s khng trnh khi nhng thiu st, mong cc Thy-C thng cm b qua v

ch dn thm cho em. Em xin lng nghe v tip thu nhng kin ng gp t Thy-

C.

Ngi thc hin

Trn Anh Trung


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TONG QUAN CHNG 1


MC LC

LI CM N trang 01

CHNG 1: TNG QUAN trang 04

CHNG 2: TNG HP TH PH TI trang 09

CHNG 3:CHN S CU TRC V S NI IN trang 15

CHNG 4: CHN MY BIN P V TNH TN THT IN NNG trang 24

CHNG 5: TNH TON NGN MCH V TDNG trang 36

CHNG 6: CHN KH CIN V CC PHN DN IN trang 43

PHN PHLC trang 67

- S NGUYN L CA TRM BIN P

- S MT BNG TRM

Ti liu tham kho:

- Thit k nh my in v trm bin p Tc gi: HYNH NHN

- Thit k nh my in v trm bin p Tc gi: NGUYN HU KHI

- Hng dn thit k n Cung cp in Tc gi: PHAN TH THU VN


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TONG QUAN CHNG 1


NHAN XET CUA GIAO VIEN


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TONG QUAN

1.1 GII THIEU TONG QUAN VE TRAM BIEN AP

1.1.1 Khai niem:

Tram bien ap la mot trong nhng phan t quan trong nhat trong he thong ien.No co nhiem vu chnh la bien ien ap en mot cap thch hp nham phuc vu choviec truyen tai va cung cap ien en phu tai tieu thu. Tram bien ap tang ap nangien ap len cao e truyen tai i xa, ngc lai tram bien ap ha ap giam ien ap

xuong thap thch hp e cap cho cac phu tai tieu thu.

1.1.2 Phan loai:

Tram bien ap c phan loai theo ien ap, quy mo va cau truc xay dng cuatram.

a. Theo ien ap th co hai loai:- Tram tang ap: thng at nhng nha may ien co nhiem vu nang ien ap

au cc may phat len cao e truyen tai i xa.

- Tram ha ap: thng at nhng tram phan phoi, no nhan ien t he thongtruyen tai roi giam ien ap xuong cap thch hp e cung cap ien cho cac phu taitieu thu.

b. Theo mc o quy mo cua tram bien ap, ngi ta chia thanh hai loai:- Tram bien ap trung gian hay con goi la tram bien ap khu vc: thng co

ien ap s cap ln, cung cap ien cho mot khu vc phu tai ln cac vung mien,tnh thanh, khu cong nghiep ln, ien ap pha s cap thng la 500; 220; 110kV, ien ap pha th cap thng la 110; 66; 35; 22; 15 kV.

- Tram bien ap phan phoi hay con goi la tram bien ap a phng: nhan ient cac tram bien ap trung gian (tram bien ap khu vc) e cung cap trc tiep cho cacphu tai nh x nghiep, khu dan c, qua cac ng day phan phoi.

c. Theo cau truc xay dng th co hai loai sau:- Tram bien ap ngoai tri: Phu hp vi cac tram khu vc va tram a phng

co cong suat ln.


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- Tram bien ap trong nha: Phu hp vi cac tram a phng va cac nha mayco cong suat nho.

1.1.3 Cac thanh phan chnh cua tram bien ap:

- May bien ap trung tam.- He thong thanh cai, dao cach ly.- He thong relay bao ve.- He thong noi at, he thong chong set.- He thong ien t dung.- Khu vc phong ieu hanh.- Khu vc phong phan phoi.

1.2 NHNG VAN E CHNH KHI THIET KE TRAM BIEN AP1.2.1 Nhng van e can lu y khi thiet ke tram bien ap:

- Tram bien ap nen at gan cac phu tai.- Thuan tien giao thong e de dang chuyen ch cac thiet b xay dng tram.- Khong nen at cac trung tam thanh pho v se lam tang chi ph au t cung

nh lam mat my quan o th.

- Nen at tram nhng ni kho rao, tranh nhng khu vc am t hoac mcnc ngam cao hn ay mong.

- Tranh at tram cac vung at de sat l.- Tranh xa cac khu vc de chay no.

Tom lai: Viec chon v tr co nh at tram bien ap la kha quan trong v nose quyet nh ve chi ph, tnh an toan va thuan tien khi van hanh.

1.2.2 Yeu cau khi thiet ke tram bien ap:

- Tram bien ap cung cap ien cho ho tieu thu la phai am bao u ien nangvi chat lng nam trong pham vi cho phep. Ngoai ra phai am bao ve mat kinh te,an toan, mot phng an c xem la hp ly khi thoa man cac yeu cau sau:

o am bao chat lng ien nang.o am bao o tin cay cao (tuy theo tnh chat loai phu tai).o Von au t thap.o An toan cho ngi va thiet b.


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o Thuan tien sa cha, van hanh.o Co tnh kha thi.

- Tuy nhien nhng yeu cau tren thng mau thuan vi nhau do o khi thiet kecan ket hp hai hoa tng yeu cau e tao ra phng an toi u.1.3 GII THIEU CHUNG VE TRAM BIEN AP SE THIET KE

Thiet ke tram bien ap 220/110/22 kV co cac thong so nh sau:

a. He thong:

Tram bien ap c noi vi he thong co cac thong so nh sau:

- Cong suat he thong: SHT = 2000 MVA.- ien khang he thong: xHT = 0,35-

Cung cap ien cho tram bang hai ng day dai = 35 kmb. Phu tai khu dn c220 kV:

Phu tai khu dn c 220 kV co cac thong so nh sau:

- Cong suat: Smax = 80 MVA- He so cong suat: cos = 0,85- So ng day: 4- o th phu tai cap 220 kV nh sau:

c. Phu tai khu nh my 110 kV:

S%

0

20

40

60

80

100

h

4 8

14

12 16 20 24


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TONG QUAN CHNG 1


Phu tai khu nh my 110 kV co cac thong so nh sau:

- Cong suat: Smax = 50 MW- He so cong suat: cos = 0,80- So ng day: 2- o th phu tai cap 110 kV nh sau:

d. Phu tai khu nng nghip 22 kV:

Phu tai khu nng nghip 22 kV co cac thong so nh sau:

- Cong suat: Smax = 30 MW- He so cong suat: cos = 0,80- So ng day: 4- o th phu tai cap 22 kV nh sau:

S%

0

20

40

60

80

100

h

4 8

14

12 16 20 24


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TONG QUAN CHNG 1


e. T dung cua tram bien ap:T dung cua tram co cac thong so nh sau:

- Cong suat: Smax = 0,5 MVA- He so cong suat: cos = 0,80

S%

0

20

40

60

80

100

h

4 8

14

12 16 20 24


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TONG QUAN CHNG 1


CHNG 2

TONG HP O TH PHU TAI

Tong hp o th phu tai la cong hai hay nhieu o th phu tai cac cap ienap do tram bien ap cung cap ien. Phu tai nay bao gom ca phan ton hao trongtruyen tai (qua may bien ap) va phan t dung phuc vu cho viec san xuat va truyentai ien nang.

T dung cua tram bien ap khong phu thuoc hoan toan vao cong suat cua

tram bien ap ma chu yeu phu thuoc vao tram bien ap co hay khong co ngi trcthng xuyen va vao he thong lam mat cua may bien ap (lam mat t nhien, quatgio, he thong bm dau, nc tuan hoan cng bc, ).

e tong hp o th phu tai co the dung phng phap ve tong hp cac o thphu tai a cho hay thanh lap bang tong hp o th phu tai theo phng phap lapbang cho P va Q tnh S neu cos khac nhau.

2.1 O TH PHU TAI CUA CAP 220 kV

Thntg s cp 220 kV:Smax = 80 (MVA) cos = 0.85 tg = 0.62So ng day: 4 x 10 km Um = 220 KV

S%

0

20

40

60

80

100

h

4 8

14

12 16 20 24


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P = S x cos = 80 x 0.85 = 68 (MW) Q = P x tg = 68 x 0.62 = 42.16 (MVar)

- T thong so cua cap 220 kV ta tnh c cac gia tr sau:STT Thi gian (h) S% S (MVA ) P (MW) Q (MVAR)

1 0 (h) -> 4 (h) 60 48 40.80 25.302 4 (h) -> 8 (h) 80 64 54.4 33.733 8(h) ->12(h) 80 64 54.4 33.734 12(h) ->14(h) 80 64 54.4 33.735 14(h) ->16(h) 80 64 54.4 33.736 16(h) ->20(h) 100 80 68 42.167 20(h) ->24(h) 80 64 54.4 33.73

Vi S = 100

%max iSS

; P = Si x cos ; Q = Pi x tg

2.2 O TH PHU TAI CUA CAP 110 kV


P = S x cos = 50 x 0.80 = 40 (MW) Q = P x tg = 40 x 0.75 = 30 (MVar)


1 0 (h) -> 4 (h) 60 30 24 18

S%

0

20

40

60

80

100

h

4 8

14

12 16 20 24


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2 4 (h) -> 8 (h) 80 40 32 243 8(h) ->12(h) 100 50 40 304 12(h) ->14(h) 80 40 32 245 14(h) ->16(h) 80 40 32 24

6 16(h) ->20(h) 100 50 40 307 20(h) ->24(h) 80 40 32 24

Vi S =100

%max iSS ; P = Si x cos ; Q = Pi x tg

2.3O TH PHU TAI CUA CAP 22 kV


P = S x cos = 30 x 0.80 = 24 (MW) Q = P x tg = 24 x 0.75 = 18 (MVar)


1 0 (h) -> 4 (h) 60 18 14.4 10.8

24 (h) -> 8 (h) 80 24 19.2 14.4

3 8(h) ->12(h) 100 30 24 184 12(h) ->14(h) 100 30 24 185 14(h) ->16(h) 100 30 24 186 16(h) ->20(h) 100 30 24 187 20(h) ->24(h) 80 24 19.2 14.4

S%

0

20

40

60

80100

h

4 8

14

12 16 20 24


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Vi S =100

%max iSS ; P = Si x cos ; Q = Pi x tg

2.4 O TH PHU TAI CUA TRAM

- e tong hp o th phu tai co the dung phng phap thanh lap bang tonghp o th phu tai theo phng phap lap bang cho P va Q tnh S, nh sau:

- Ta c bang thong so cua tram nh sau:Thi gian P(110

kV)P(22k

V)P(MW)

Q(110kV)

Q(22kV) Q(MVAR)

S(MVA)

S%

0 -> 4 (h) 24 14.4 38.4 18 10.8 28.8 48 60

4 -> 8 (h) 32 19.2 51.2 24 14.4 38.4 64 808 ->12(h) 40 24 64 30 18 48 80 10012->14(h) 32 24 56 24 18 42 70 87.514->16(h) 32 24 56 24 18 42 70 87.516->20(h) 40 24 64 30 18 48 80 10020->24(h) 32 19.2 51.2 24 14.4 38.4 64 80Vi P = Pi Q = Qi

S = Si S% = %100max

xS

Sj

Pi : Cong suat tac dung cap ien ap th i (110 KV, 22 KV).Qi : Cong suat phan khang cap ien ap th i (110 KV, 22 KV).Si : Cong suat bieu kien cap ien ap th i (110 KV, 22 KV).Sj : Cong suat bieu kien toan tram khoang thi gian th j


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Thong thng, tram bien ap con co he so t dung. T dung cua tram bienap khong phu thuoc hoan toan vao cong suat cua tram bien ap ma chu yeu phuthuoc vao tram bien ap co hay khong co ngi trc thng xuyen va phu thuoc vaohe thong lanh cua may bien ap (co quat, co he thong bm dau, nc cng bc). Vthe, bang tong hp o th phu tai cua toan tram bien ap nh sau:

Phu tai cap ien ap (S theo tng cap ien ap)Tht

Thi gianU=110 KV U=22 KV T dung Tong %S

1 0 (h) -> 4 (h) 30 18 0.5 48.5 60.22 4 (h) -> 8 (h) 40 24 0.5 64.5 80.13 8(h) ->12(h) 50 30 0.5 80.5 1004 12(h) ->14(h) 40 30 0.5 70.5 87.65 14(h) ->16(h) 40 30 0.5 70.5 87.66 16(h) ->20(h) 50 30 0.5 80.5 1007 20(h) ->24(h) 40 24 0.5 64.5 80.1

Tong = S110KV + S22KV + St dung

Vi: %S = %100max xSSi

Si: Cong suat bieu kien thi gian th i.Smax = 80.5 (MVA).


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- T bang thong so tren ta xay dng c o th phu tai cua tram nh sau:

He so cong suat trung bnh toan tram la:

costb

=max2max1

2max21max1 cos*cos*

SS

SS

+

+ =

80

8.0*308.0*50 += 0.8

Tong cong suat cua toan tram la:

Stram = TDKVKV SSS ++ 22max110max = 50 + 30 + 0.5 = 80.5 (MVA)Cong suat tac dung cua toan tram la:

Ptram = Stram * cos tb = 80.5 * 0.8 = 64.4 (MW)

Cong suat cua he thong:PHT = SHT * cos HT = 2000 * 0.8 = 1600 (MW)

T o ta thay cong suat cua he thong u kha nang ap ng yeu cau cua phutai ke ca trong trng hp phu tai cc ai.

2.5 NHAN XET

Tren o th phu tai cua tram ta thay phu tai tieu thu khong eu, o th khongbang phang, thi gian phu tai tieu thu ien nang nhieu nhat vao luc t 08 gi en12 gi v t 16 gin 20 gi. Cong suat tieu thu cc ai la 80.5 MVA va cc tieula 48.5 MVA o chenh lech gia hai gia tr nay la tng oi cao. Do o, khi chonla may bien ap can chu y en kha nang qua tai va tuoi tho cua may bien ap.

8 12 16 20 24144

64.5

80.580.5

64.5

70.5

48.5

0

60.2

80.1

100


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CHNG 3

CHON S O CAU TRUC

3.1 GII THIEU S O CAU TRUC

- S o cau truc cua tram bien ap la s o dien ta s lien quan gia nguon, taiva he thong ien.

- oi vi tram bien ap nguon thng la cac ng day cung cap t he thongen tram bien ap, co nhiem vu am bao cung cap cho cac phu tai ma tram bien apam nhan.

- Khi thiet ke tram bien ap, s o cau truc la phan quan trong co anh hngquyet nh en toan thiet ke. Cac yeu cau chnh khi chon s o:

o Co tnh kha thi tc la co the chon c cac thiet b chnh nh maybien ap, may cat, cung nh co kha nang thi cong xay lap van hanh.

o am bao lien he chat che gia cac cap ien ap ac biet vi he thongkhi bnh thng cung nh cng bc.

o Ton hao qua may bien ap be, tranh trng hp cung cap cho phu taiqua hai lan bien ap khong can thiet.

o Von au t hp ly, chiem dien tch cang be cang tot.o Co kha nang phat trien trong tng lai gan, khong can thay the cau

truc a chon.

- Trong thc te rat kho am bao cac yeu cau v cac ieu kien co s mau thuanvi nhau. V vay trong tng trng hp cu the ta chon s o thch ng e am baotnh ky thuat, kinh te.

- Khi thiet ke tram bien ap ta a ra nhieu phng an kha thi tren c s phantch u khuyet iem cua tng phng an; so sanh ieu kien ky thuat kinh te roichon phng an toi u.

3.2 CHON SO LNG MAY BIEN APChon so lng may bien ap cho cho tng cap ien ap cua tram phai can c

vao nhng ieu kien: o tin cay cung cap ien, cong suat cua phu tai can cung capva tnh kinh te.

Do o, ta co cac phng an chon la so lng may bien ap nh sau:


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3.2.1 Mot may bien ap:

- c dung trong trng hp phu tai khong quan trong, tram c cung capbang mot ng day t he thong.

- Tram bien ap khi xay dng thng chia lam hai giai oan, giai oan au atmot may, sau nay khi phu tai phat trien th ta lap at them may th hai.- Thiet ke nh vay von au t ban au nho, tan dung von au t ban au tot

hn. Tuy nhien, tnh lien tuc trong cung cap ien trong trng hp nay la khongcao.

3.2.2 Hai may bien ap:

- La phng an c s dung nhieu nhat v tnh am bao lien tuc cung capien cao. Phng an thng c thiet ke khi:

oCo hai ng day cung cap t he thong.

o Khi khong co mot may bien ap ln phu hp vi phu tai.o Khong co kha nang chuyen ch va xay lap mot may bien ap ln.

3.2.3 Ba may bien ap:

- Phng an nay ch c s dung khi khong co hai may bien ap phu hp hoactram a xay dng ma phu tai phat trien khong co kha nang thay the hai may miphai at them may th ba.

- at ba may bien ap ngay t au thng t c s dung v von au t cao,dien tch xay lap ln, phc tap, 3.3 CAC PHNG AN LA CHON

3.3.1 Nhan nh chung:

Tram bien ap se thiet ke gom cap ien ap 220 kV (cap he thong), 110 kV va22 kV (cap phu tai). Trong o cap 110 kV la phu tai loai 1 va 22 kV la phu tai loai1 va loai 3 nen khong the dung mot may bien ap lam may bien ap chnh v khi sco se mat ien hoan toan. Do o ta can dung 2 may bien ap lam may bien apchnh e am bao cap ien lien tuc cho phu tai loai 1 va cung khong the dungnhieu hn v chi ph se cao.

3.3.2 Ta xem xet mot so phng an sau:

3.3.2.1 Phng an 1: Dung 2 may bien ap t ngau 220/110/22 kV.

- Phu tai cap ien ap 110 kV va 22 kV c lay t cuon trung va cuon ha maybien ap.


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TONG QUAN CHNG 1


- Cac cap ien ap cao, trung eu co trung tnh noi at trc tiep nen dung maybien ap t ngau se co nhieu u iem hn so vi may bien ap ba cuon day.

- u iem:o o tin cay cao.o am bao cung cap ien lien tuc.o S o cau truc ro rang.o So lng may bien ap t.o Ton that ien nang be.o Von au t thap.


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TONG QUAN CHNG 1


o ieu chnh ien ap de dang do ien khang cuon cao, cuon trung eunho.

o Trong lng, kch thc be hn dung may bien ap ba cuon day.-

Khuyet iem:o Kho chon may bien ap co cong suat phu hp.o Cong suat ln keo theo kch thc va trong lng may bien ap ln co

the gap kho khan khi van chuyen va lap at.

o Do mang cao ap va trung ap trc tiep noi at va co s lien he ve iengia cuon cao va cuon trung trong may bien ap nen phai co chong set van botr au vao ra may bien ap.

3.3.2.2 Phng an 2: Dung 2 may bien ap hai cuon day 220/110 kV va 2 may

bien ap hai cuon day 110/22 kV.


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TONG QUAN CHNG 1


- u iem:o o tin cay cao.o am bao cung cap ien lien tuc.o Cau truc ro rang.o Phu hp vi nhng ni van chuyen kho khan.

- Khuyet iem:o So lng may bien ap nhieu.o Gia thanh cao.o Ton that ien nang ln v cap 22 kV phai qua hai lan bien ap.

3.3.2.3 Phng an 3: Dung 2 may bien ap hai cuon day 220/110 kV

2 may bien ap hai cuon day 220/22 kV


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TONG QUAN CHNG 1


- u iem:o o tin cay cao.o am bao cung cap ien lien tuc.o Cau truc ro rang.o Phu tai moi cap ch qua mot lan may bien ap.

- Khuyet iem:o So lng may bien ap nhieu.o Von au t ln.o Ton that ien nang ln.o Kho chon c may bien ap 220/22 kV.

3.3.2.4 Phng an 4: Dung 2 may bien ap ba cuon day 220/110/22 kV:

HE THONG

220 kV

110 kV

22 kV

Hnh 3.4: S o cau truc dung 2 may bien ap ba cuon day


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TONG QUAN CHNG 1


- u iem:o o tin cay cao.o am bao cung cap ien lien tuc.o S o cau truc ro rang.o So lng may bien ap t.o Ton that ien nang be.o Von au t thap.

- Khuyet iem:o Kho chon may bien ap co cong suat phu hp.o Cong suat ln keo theo kch thc va trong lng may bien ap ln co

the gap kho khan khi van chuyen.3.3.3 NHAN XET

- Phng an 1 va 4 n gian v ch s dung hai may bien ap nen nhn s bo seton hao ien nang nho hn 2 phng an con lai, hn na khi s dung t may bien apth so lng may cat se t va dien tch tram se nho.

- Phng an 2 s dung bon may bien ap nen se ton nhieu dien tch tram, chiph cao. Mat khac, phu tai 22 kV phai chu ton that qua hai lan may bien ap nenhieu suat truyen tai giam, chi ph tang.

- Phng an 3 ngoai viec phai s dung bon may bien ap no con co nhciem ln nhat la o lech ien ap gia s cap va th cap ln (220/22 kV) lam tnhkha thi cua phng an giam v hau nh khong chon c may bien ap thch hp.Neu at hang th se lam tang chi ph va kho thay the ve sau nay.

Nhn xt: trong 4 phng n trn ta chn phng n 1 v c nhiu u im v phhp vi yu cu thit k trm bin p, p ng thc t ca ngnh in nc ta vphng din k thut cng nh cc yu cu v kinh t.

3.4 CHON S O NOI IEN

S o noi ien la mot hnh ve bieu dien quan he gia cac thiet b, kh cu

ien co nhiem vu nhan ien t cac nguon ien e cung cap phan phoi cho cac phutai cung mot cap ien ap.

o Nguon ien co the la may phat ien, may bien ap, ng day cungcap,

o Phu tai co the la may bien ap, ng day,


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TONG QUAN CHNG 1


o Moi nguon hay tai goi la mot phan t cua s o noi ien.o Thanh gop la ni tap trung cac nguon ien va phan phoi cho cac phu

tai.

-

S o noi ien co nhieu dang khac nhau phu thuoc vao cap ien ap, so phant nguon va tai, cong suat tong, tnh chat quan trong cua cac phu tai,

Yeu cau cua s o noi ien:

- Tnh am bao cung cap ien: theo yeu cau hay s quan trong cua phu tai mamc o am bao tng ng. Tnh am bao cua s o noi ien co the anh gia quao tin cay cung cap ien, thi gian ngng cung cap ien, ien nang khong cung capu cho cac ho tieu thu hay la s thiet hai cua phu tai do khong am bao cung capien.

- Tnh linh hoat: the hien s thch ng vi cac che o lam viec khac nhau.V du: khi phai ngng mot phan t nguon hay tai (che o lam viec cng bc).

- Tnh phat trien: s o noi ien phai ap ng khong nhng hien tai ma catrong tng lai gan khi tang them nguon hay tai. Khi phat trien khong gap kho khanhay phai pha bo thay oi cau truc s o hien hu.

- Tnh kinh te: the hien von au t ban au va cac chi ph hang nam. Tnhkinh te cua s o c quyet nh bi hnh thc thanh gop, kh cu va so lng thietb dung cho s o.

V du: ton that ien nang qua may bien ap.

- Tnh hien ai: can quan tam en tnh hien ai cua s o cung nh xu thechung, ac biet s tien bo trong che tao, cau truc cua cac kh cu ien nh may catien.

- Cac dang s o noi ien c ban:o S o he thong mot thanh gop.o S o he thong mot thanh gop co phan oan.o S o he thong mot thanh gop co thanh gop vong.o

S o he thong hai thanh gop.o S o he thong hai thanh gop co phan oan.o S o he thong hai thanh gop co thanh gop vong.o S o a giac.


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TONG QUAN CHNG 1


220 KV

22 KV

0,4 KV

110 KV

May bien apt dung

HE THONG

May cat hp bo

Dao cach li hp bo

Dao cach li


24/67

TONG QUAN CHNG 1


CHNG 4

CHON MAY BIEN AP VA TNH TON THATTRONG MAY BIEN AP

4.1KHAI NIEM CHUNG

- May bien ap la thiet b truyen tai ien nang t ien ap nay en ien apkhac. ien nang san xuat t nha may ien c truyen tai en cac ho tieu thu xaphai qua ng day cao the 110, 220, 500 kV, thng qua may bien ap tang aplen ien ap tng ng.

- cuoi ng day cao ap lai can may bien ap giam ve ien ap thch hp vimang phan phoi, v du 22, 15, 0,4 kV,

- Trong he thong ln thng phai qua nhieu lan tang, giam mi a ien nangt cac may phat ien en ho tieu thu. V vay tong cong suat may bien ap trong hethong ien co the bang 4 en 5 lan tong cong suat cua cac may phat ien.

- Mac du hieu suat cua cac may bien ap tng oi cao nhng ton that qua maybien ap hang nam van rat ln.

4.1.1 Khi s dung may bien ap can lu y cac ac iem sau ay:

- May bien ap la thiet b khong phat ra ien nang ma ch truyen tai ien nang.Trong he thong ien ch co may phat ien mi phat ra cong suat tac dung P vacong suat phan khang Q.

- May bien ap thng che tao thanh mot khoi tai nha may, phan co the thaori ra trong khi chuyen ch chiem t le rat nho (khoang 10%), cho nen trong lng,kch thc chuyen ch rat ln. V vay khi thiet ke can chu y en phng tien vakha nang chuyen ch khi xay lap.

- Tien bo khoa hoc ve che tao (chu yeu ve vat lieu cach ien, thep t) tien borat nhanh, cho nen cac may bien ap che tao cang ve sau kch thc, trong lng,ton hao va ca gia thanh eu be hn. Do o, khi chon cong suat may bien ap cantnh en kha nang tan dung toi a (xet kha nang qua tai cho phep) tranh s vanhanh non tai may bien ap a en ton hao khong tai ln, keo dai thi gian s dungkhong can thiet.


25/67

TONG QUAN CHNG 1


- Tuoi tho va kha nang tai cua may bien ap chu yeu phu thuoc vao nhiet okhi van hanh. Nhiet o cac phan cua may bien ap khong ch phu thuoc vao congsuat qua may bien ap ma con phu thuoc vao nhiet o moi trng xung quanh vaphng phap lam mat.

- Cong suat nh mc cua may bien ap c che tao theo thang tieu chuan cuamoi nc, thng cach nhau ln, nhat la khi cong suat cang ln. ieu nay a enneu tnh toan khong chnh xac co the phai chon may bien ap ln khong can thiet.

- Khi chon cong suat cua may bien ap phai chu y en kha nang phat trien phutai, tranh trng hp va xay dng xong tram bien ap lai phai thay oi hay atthem may bien ap v phu tai tang. ieu nay can can nhac rat khoa hoc va thc temi co the chon cong suat toi u thoa man tat ca cac ieu kien a neu tren.

- May bien ap hien nay co nhieu loai:o May bien ap mot pha, ba pha.o May bien ap hai cuon day, ba cuon day.o May bien ap co cuon day phan chia.o May bien ap t ngau mot pha, ba pha.o May bien ap tang ap, ha ap.o May bien ap co va khong co ieu ap di tai.

- May bien ap lai do nhieu nc che tao theo tieu chuan khac nhau, ieu kienlam viec cung co the khac nhau khi thiet ke cung can chu y kha canh nay.4.1.2 He thong lam mat may bien ap:

- Co nhieu phng phap, moi phng phap lam mat yeu cau ieu kien vanhanh nhat nh, khi khong thc hien ung quy nh co the lam tang nhiet o maybien ap a en giam tuoi tho, tham ch a en chay may bien ap. Lam mat maybien ap co cac phng phap sau:

o Lam mat may bien ap theo quy luat t nhien.o Lam mat may bien ap bang dau co them quat e tang cng kha nang

trao oi nhiet va tan nhiet.

o Lam mat bang phng phap tuan hoan cng bc dau va co tangthem quat.

o Lam mat dau bang nc.


26/67

TONG QUAN CHNG 1


o Lam mat kieu kho.4.2TNH TOAN CHON CONG SUAT MAY BIEN AP

- e am bao cung cap ien 100% cho phu tai, ta chon may bien ap theo ieukien qua tai s co v cac tram theo phng an a chon eu co hai may bien ap macsong song nen khi mot may gap s co th may con lai co the lam viec qua tai them40% trong 5 ngay em, moi ngay khong qua 6 gi. Khi phu tai cua may bien aptrc khi qua tai khong vt qua 0.93 so vi cong suat danh nh, ta chon theo ieukien:

Theo o th phu tai ang tr ve hai bac, trong o K1 < 0,93; K2 < 1,4 oi vimay bien ap at ngoai tri va K2 < 1,3 neu may bien ap at trong nha, T2 < 6 gi,chu y theo doi nhiet o cuon day khong c vt qua 1400C va tot nhat la tangcng toi a cac bien phap lam mat may bien ap.

- Che o qua tai s co la che o cho phep lam viec cua may bien ap trongieu kien s co nen ta chon may bien ap theo ieu kien qua tai s co:

Kqtsc.Sm> Smax Sm>qtscK

Smax , vi:

o Kqtsc = 1,4 (may bien ap at ngoai tri)o Kqtsc = 1.3 (may bien ap at trong nha)o Sm la cong suat nh mc may bien ap.o Smax la cong suat cc ai cua tai qua may bien ap.

- Can c vao SmB a chon tnh he so tai Ki cua cac bac o th phu tai:Ki =

mB

i

SS

Ki >1: Qua tai

Ki 1 theo cong thc:

K2t =i

i2i

T)T*K(

Neu K2t > 0.9*Kmax th K2 = Kt va T2 = iT .

Neu K2t < 0.9*Kmax th K2 = 0.9*Kmaxva T2 c xac nh theo cong thc:

T2 = 2max

i2i

)K*9.0()T*K(


27/67

TONG QUAN CHNG 1


Trng hp neu co nhieu vung khong lien tuc co Ki >1 th lay vung nao co

tong i2i T*K ln nhat e tnh K2 nh tren, cac vung con lai e xem xet khi xacnh K1.

- Xac nh K1 ch can ang tr o th phu tai trong khoang thi gian 10 gitrc vung a tnh K2 (ke ca phan co K1>1 khong xet trong trng hp trentrong khoang 10 gi) theo cong thc:

K1t =10

)T*K( i2i

Neu chon may bien ap theo ieu kien qua tai s co, th K1 < 0.93; K2 < 1.4;T2 < 6 gi. Chu y theo doi nhiet o cua cuon day khong vt qua 140oC va tot nhat

la tang cng toi a cac bien phap lam lanh may bien ap e may bien ap van hanhat hieu qua cao nhat.Chon so lng may bien ap:

So lng va cong suat cua may bien ap c xac nh theo cac tieuchuan ky thuat sau:

- An toan, lien tuc cung cap ien.- Von au t be nhat.- Chi ph van hanh hang nam thap nhat.- Ngoai ra con chu y en viec tieu ton kim loai mau t nhat, cac kh cu va thiet

b ien phai co the thay the mot cach de dang, dung lng may bien aptrong mot tram nen ong nhat

Tnh toan chon cng sut my bin p may bien ap:Chn 2 my bin p tngu:

o th phu tai cua toan tram:


28/67

TONG QUAN CHNG 1


T o th phu tai, ta co:

Smin SmMBA Smax 48.5 (MVA) SmB 80.5 (MVA)

va SmB qtsc

max

KS

=4.15.80 = 57.5 (MVA)

vi Kqtsc = 1.4 (do may bien ap at ngoai tri)

V the cac loai may bien ap t ngu co the chon: 63 MVA, 90 MVA

Vi may bien ap t ngau co S = 63 MVA, ta tien hanh kiem tra qua tai s cocua may bien ap ta co bang gia tr sau:

Thi gian 0->4h 4->8h 8->12h 12->14h 14->16h 16->20h 20->24hSi (MVA) 48.5 64.5 80.5 70.5 70.5 80.5 64.5

Ki = Si/SB 0.77 < 1 1.02 1.28 1.12 1.12 1.28 1.02(Ki)2 0.59 1.04 1.64 1.25 1.25 1.64 1.04

Ti (gi) 4 4 4 2 2 4 4(Ki)2*Ti 2.36 4.16 6.56 2.5 2.5 6.56 4.16

8 12 16 20 24144

64.5

80.580.5

64.5

70.5

48.5

100

60.2

0

80.1


29/67

TONG QUAN CHNG 1


K2t =i

i2i

T)T*K(

=

20

16.456.65.25.256.616.4 +++++ = 1.15

max

t2

K

K

= 28.115.1

= 0.898 < 0.9 nn K2 = 0.9*Kmax = 0.9*1.28 = 1.152

Vy K2 = 1.152 < 1.4

T2 = 2max

i2i

)K*9.0()T*K(

=2)28.1*9.0(

16.456.65.25.256.616.4 +++++ =4.46

Vy T2 = 4.46 (gi) < 6 (gi).

V the ta tnh K1 bang cach:

K1t =10

)T*K( i2i =10

28.316.436.2 ++ = 0.99

K1 =max

1

K

Kdt =

28.1

99.0 = 0.77

Vy K1 = 0.77 < 0.93

Vy my bin p t ngu c Sm = 63 MVA tha cc iu kin qu ti s c.

May bien ap t ngu ba pha 63 MVA co cac thong so sau:

Sm(MVA)

in p (kV) UN% I0% P0(kW)

PN (kW)

Cao Trung H C/T C/H T/H C/T C/H T/H63

230 121 38.5 11 35 220.5 45

400 220 240


30/67

TONG QUAN CHNG 1


Chn 2 my bin p 3 pha 2 cun dy:

Thi gian S22 (MVA) STD (MVA) S22TD (MVA)0 (h) -> 4 (h) 18 0.5 18.54 (h) -> 8 (h) 24 0.5 24.58(h) ->12(h) 30 0.5 30.5

12(h) ->14(h) 30 0.5 30.514(h) ->16(h) 30 0.5 30.516(h) ->20(h) 30 0.5 30.520(h) ->24(h) 24 0.5 24.5

T bng ph ti 22 kV v t dung ta c Smax = 30.5 (MVA). Cng sut mybin p chn theo iu kin 1 my bin p ngh, my bin p cn li vi kh nng quti s c c kh nng cung cp Smax = 30.5 (MVA)

Ta c: Smin SmMBA Smax 18.5 (MVA) SmB 30.5 (MVA)

va SmB qtsc

maxKS = 4.1 5.30 = 21.8 (MVA)

vi Kqtsc = 1.4 (do may bien ap at ngoai tri)V th may bien ap 3 pha 2 cun dy co the chon: 30 MVATa tien hanh kiem tra qua tai s co cua may bien ap ta co bang gia tr sau:

8 12 16 20 24144

64.5

80.580.5

64.5

70.5

48.5

100

60.2

0

80.1

SB = 63MVA


31/67

TONG QUAN CHNG 1


Thi gian 0->4h 4->8h 8->12h 12->14h 14->16h 16->20h 20->24hSi (MVA) 18.5 24.5 30.5 30.5 30.5 30.5 24.5Ki = Si/SB 0.62 < 1 0.81< 1 1.02 1.02 1.02 1.02 0.81< 1

(Ki)2 0.38 0.66 1.04 1.04 1.04 1.04 0.66

Ti (gi) 4 4 4 2 2 4 4(Ki)2*Ti 1.52 2.64 4.16 2.08 2.08 4.16 2.64

K2t =i

i2i

T)T*K(

=12

16.408.208.216.4 +++ = 1.02

max

t2

KK

=02.1

02.1 = 1 > 0.9 nn K2 = K2t= 1.02

Vy K2 = 1.02 < 1.4

V T2 = 12 (gi) > 6 (gi) (khng tha)

Vy ta chn nng cng sut my bin p ln Sm = 31.5 MVAV my bin p 31.5 MVA > Smax = 30.5 MVA nn khng cn kim tra qu ti

cho my bin p nyCc thng s ca my bin p 3 pha 2 cun dy 31.5 MVA:

Sm (MVA) in p (kV) UN% I0% P0 (kW) PN (kW)

Cao H31.5115 38.5

10.5 2.7 36 200

4.3 TNH TOAN TON THAT TRONG MAY BIEN AP4.3.1 Gii thieu s lc ve ton that trong may bien ap va he

thong ien:

- Nh chung ta a biet ton that ien nang trong he thong ien, noi chung gaythiet hai khong nho ve chi ph van hanh. Trong o co rat nhieu ton that nh: tonthat trong may bien ap, ton that tren day dan khi truyen tai, ton that vang quang(oi vi ien ap cao), trong o ton that trong may bien ap la ton that chu yeu.Ton that nay gom hai thanh phan:

o Ton that sat, no khong phu thuoc vao phu tai va no chnh la ton thatkhong tai cua may bien ap.

o Ton that ong phu thuoc vao phu tai. Khi phu tai bang cong suat nhmc cua may bien ap th ton hao nay chnh la ton hao ngan mach .


32/67

TONG QUAN CHNG 1


- Co rat nhieu loai may bien ap nh: may bien ap ba pha hai cuon day, ba phaba cuon day, t ngau ba pha, Moi loai may eu co cach tnh khac nhau. Tuynhien v cac may bien ap trong ba phng an ta s dung la may bien ap ba pha haicuon day, ba pha ba cuon day, t ngau ba pha nen ta ch a ra cac cong thc e

tnh ton that cho ba loai may nay.4.3.1.1 Ton that ien nang trong may bien ap t ngau:

- He so co li cua may bien ap t ngau: = 1

C

T

U

U = 1 220

110 = 0,5

PN.C = 0,5.

+

2.

2.

.

THNCHNCTN

PPP

PN.T = 0,5.

+

2.

2.

.

CHNTHNCTN

PPP

PN.H = 0,5.

+

CTN

THNCHN

P

PP.2

.2.

- Khi co o th phu tai ton that ien nang qua may bien ap la:

A = n.P0.t +n

1 .

++

idm

iH

HNdm

iT

TNdm

iC

CNt

S

SP

S

SP

S

SP .... 2

2

.2

2

.2

2

.

Trong o:o A la ton that ien nang trong may bien ap tnh trong mot ngay

em.o n la so may bien ap van hanh song song.o P0 la ton that khong tai.o t la thi gian van hanh trong mot ngay em.o PN.C la ton that ngan mach trong cuon cao.o PN.T la ton that ngan mach trong cuon trung.o PN.H la ton that ngan mach trong cuon ha.o SiC la cong suat truyen qua cuon cao tng ng vi thi gian ti.o SiT la cong suat truyen qua cuon trung tng ng vi thi gian ti.o SiH la cong suat truyen qua cuon ha tng ng vi thi gian ti.o Sm la cong suat nh mc cua may bien ap.

4.3.1.2 Ton that ien nang trong may bien ap ba pha hai cuon day:-

Khi co o th phu tai ton that ien nang qua may bien ap la:A = n.P0.t +

n

1 .PN. iidm

tSS

..1 22


em.


33/67

TONG QUAN CHNG 1


o n la so may bien ap van hanh song song.o P0 la ton that khong tai.o t la thi gian van hanh trong mot ngay em.o PN la ton that ngan mach trong may bien ap.o Si la cong suat truyen qua may bien ap tng ng vi thi gian ti.o Sm la cong suat nh mc cua may bien ap.

4.3.1.3 Ton that ien nang trong may bien ap ba pha ba cuon day:- Coi nh ty le cong suat cua may bien ap la 100/100/100, ton that ngan mach

trong tng cuon day may bien ap c xac nh nh sau:PN.C = 0,5.(PN.CT + PN.CH - PN.TH)PN.T = 0,5.(PN.CT + PN.TH - PN.CH)PN.H = 0,5.(PN.CH + PN.TH - PN.CT)

- Chu y: Mot so may bien ap nha che tao ch cho mot thong soPN.CH co thexem ton that ngan mach gia cac cuon day bang nhau va ng nhien khi o:PN.C = PN.T = PN.H = 0,5.PN.CH

- Khi co o th phu tai ton that ien nang qua may bien ap la:A = n.P0.t +

dmSn2.

1 . ( ) ++ iHiHHNiTiTTNiCiCCN tSPtSPtSP ... 2.2.2.


em.o n la so may bien ap van hanh song song.o P0 la ton that khong tai.o

t la thi gian van hanh trong mot ngay em.o Sm la cong suat nh mc cua may bien ap.o PN.C la ton that ngan mach trong cuon cao.o PN.T la ton that ngan mach trong cuon trung.o PN.H la ton that ngan mach trong cuon ha.o SiC la cong suat truyen qua cuon cao tng ng vi thi gian tiC.o SiT la cong suat truyen qua cuon trung tng ng vi thi gian tiT.o SiH la cong suat truyen qua cuon ha tng ng vi thi gian tiH.

TNH TOAN TON THAT IEN NANG MAY BIEN AP TNGU)P( B goi la ton that qua may bien ap

BP = OP +2

mB

tN

S

SP

May bien ap t ngau cap 220 kV / 110 kV / 22 kV vi cac thong so sau:


34/67

TONG QUAN CHNG 1


T so cong suat cac cuon cao, trung, ha la 100 / 100 / (viC

T

U

U=1 = 0.5).

Sm

(MVA)

in p (kV) UN% I0% P0

(kW)

PN (kW)


230 121 38.5 11 35 220.5 45

400 220 240

PN.C = 0.5

+

2.

2.

.

THNCHNCTN

PPP = 0.5

+

22 5.0

240

5.0

220400 = 160 (kW)

PN.T = 0.5

+

2.

2.

.

CHNTHNCTN

PPP = 0.5

+

22 5.0

220

5.0

240400 = 240 (kW)

PN.H = 0.5

+

CTNTHNCHN P

PP.2.2. = 0.5

+ 4005.0

240

5.0

22022 = 720 (kW)

Ta c: ngayA = 2 0P t + 0.5

++ I2

mB

2IH

NH2mB

2IT

NT2mB

2IC

NC t.SS

.PSS

.PSS

.P

vi I2IC T.S = 48.5

2.4 + 64.52.4 + 80.52.4 + 70.52.2 + 70.52.2 + 80.52.4 +64.52.4

= 114414 (MVA)2.h.

I2IT T.S = 30

2.4 + 402.4 + 502.4 + 402.2 + 402.2 + 502.4 +402.4= 42800 (MVA)2.h.

I

2

IH T.S = 18.52

.4 + 24.52

.4 + 30.52

.4 + 30.52

.2 + 30.52

.2 + 30.52

.4 + 24.52

.4= 17334 (MVA)2.h.Suy ra ton that ien nang trong mot ngy m la:

ngayA = 2 45 24 + 26321

(160114414 + 24042800 + 72017334)

= 7332.4 kWhVay ton that ien nang trong mot nam la:

namA = 7332.4 365 = 2676326 (kWh).

Phan tram ton that:vi: Tong ien nang tieu thu trong mot ngay:

ngayA = Pi Ti = 38.44 + 51.24 + 644 + 562+562+644+51.24= 1299.2 (MWh).

ien nang tieu thu trong mot nam la:

namA = ngayA 365 = 1299.2 365 = 474208 (MWh).

Ton that phan tram ien nang trong mot nam:


35/67

TONG QUAN CHNG 1


%A = %100*A

A nam

= %100*

474208000

2676326 = 0.56% < 5%

TNH TOAN TON THAT IEN NANG MAY BIEN 3 PHA 2 CUN DY

Khi co o th phu tai

ii

m

N tSSn

PtPnA

+= 220

1

Ta c: II TS .2 = 304 + 404 + 504 + 402+402+504 + 404

= 1000 (MVA)2h

10005.31

1

2

20024362

2+= ngyA = 1828.8 (kWh)

Vay ton that ien nang trong mot nam la:

namA = 1828.8 365 = 667512 (kWh)


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TONG QUAN CHNG 1


CHNG 5

TNH TOAN NGAN MACH

5.1LY THUYET TNH TOAN NGAN MACH

Khi anh gia va la chon nha may ien, he thong cung nh tram bien apkhong nhng can phai quan tam en dong ien va ien ap bnh thng ma con phaiquan tam en van e ngan mach. Dong ien khi ngan mach ln hn nhieu lan so

vi dong ien nh mc nen co the gay ra ng suat nhiet va ng suat ong rat ln.Trong trng hp ngan mach cham at co the sinh ra ien ap tiep xuc khong chophep va xay ra hien tng nhieu trong he thong ien.

Neu dong ien ngan mach khong c tnh en trong giai oan thiet ke, thnhng hau qua cua no co the lam h hong thiet b cung nh cac kh cu ien vanguy hiem cho ca con ngi. Dong ien ngan mach nho nhat co the cung can phaixac nh v no co y ngha quan trong trong viec la chon thong so ky thuat cho cacthiet b bao ve.

5.1.1 Khi tnh toan dong ien ngan mach can quan tam cac gia thiet sau:

- Ch tnh ngan mach ba pha N(3), v thng dong ngan mach ba pha ln hndong ngan mach hai pha N(2) va mot pha N(1).

- Nguon cung cap cho dong ngan mach la he thong cac may phat nhiet vathuy ien. May bu ong bo, ong c ien ch xet khi ngan mach tren cc cua no vkhi ngan mach qua ien khang ln, cac dong ngan mach nay nho va a tat.

- Sc ien ong cua cac nguon khi ngan mach xa qua ien khang ln (x*m >3) c coi la khong oi.

- Khi tnh toan ngan mach trong he thong U > 1000V co the bo qua thanhphan ien tr R ma ch xet ien khang X, v R thng nho hn X nhieu. Khi tnhngan mach trong mang U < 1000V mi xet en R.

22 XRz +=

- Thi gian ton tai ngan mach bang thi gian bao ve relay (tbv) va thi gianmay cat lam viec (tMC): tN = tbv + tMC


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TONG QUAN CHNG 1


- Co the xem dong ngan mach khong oi trong thi gian ton tai ngan mach, doo:

I = It = Io

trong o:o I- la dong ien ngan mach sieu qua oo It la dong ngan mach tai thi iem to Io la dong ngan mach on nh.

- Tnh ngan mach trong he tng oi vi cbS va cbU ; khi ch co mot hoac haicap ien ap mi tnh trong he co ten:

cb

cb

cbU

SI

3=

5.1.2 Trnh t tnh toan ngan mach ba pha:

- Ve s o he thong can tnh toan ngan mach va xac nh cac iem can tnhtoan ngan mach Ni.

- T s o nguyen ly thay the cac phan t bang mo hnh hoa cua no, ghi vaanh so th t xi cua cac ien khang.

- Chon cac thong so trong he c ban: Scb, Ucb suy ra Icb cac cap can tnh dongngan mach.

- Tnh tr so c ban tng oi cua cac ien khang xi.- Lan lt bien oi s o ve s o ang tr ch co mot nguon va ien khang

tong tng ng cho tng iem ngan mach xi.

- Tnh dong ngan mach cua tng iem ngan mach theo bieu thci

cb

cbNikANi

i

Nix

IIII

xI

=== .;1 *

)(*

o Trong o: Icb la tr c ban cua dong ngan mach tng ng vi ienap tai iem ngan mach.

5.2TNH TOAN NGAN MACH- Tram bien ap ang thiet ke c noi vi he thong bang hai ng day vi

chieu dai 35 km.

5.2.1 Tnh toan ngan mach trong he tng oi c ban:

5.2.1.1 Cac cong thc can thiet e xac nh ien khang:


38/67

TONG QUAN CHNG 1


- ien khang may bien ap:o May bien ap t ngau:

%.CNU =

2

1

+

%.

%.%

.THNCHN

CTN

UUU xC =

100

%.CNU .

dm

cb

S

S

%.TNU = 2

1

+

%.

%.%

.CHNTHN

CTN

UUU xT =

100

%.TNU .

dm

cb

S

S

%.HNU = 2

1

+

%.

%.

%.

CTNCHNTHN U

UU

xH =

100

%.HNU .

dm

cb

S

S

- ien khang ng day: xd = x0.l.cb

cb

U

S2

vi: x0 = 0.4(/km) la ien khang cua 1 km day dan; l la chieu dai day dan.

- ien khang cua he thong: xHT = *HTx . cbHT

SS

5.2.1.2 Cac ai lng c ban:

Cong suat c ban: Scb =2000 MVA.

- ien ap c ban: Ucb1 = 230 kV; Ucb2 = 121 kV; Ucb3 = 38.5 kV.- T o suy ra dong ien c ban:

Icb1 = 1.3 cbcb

U

S

= 230.3

2000

= 5.02 kA; Icb2 = 2.3 cbcb

U

S

= 121.3

2000

= 9.54 kA.

Icb3 =3.3 cb

cb

U

S =5.38.3

2000 = 29.99 kA

- Ta co:o ien khang cua he thong: xHT = *HTx cb

HT

S

S= 0.35

2000

2000 = 0,35 vt

o ien khang ng day: xd = x0 l1

2cb

cb

U

S = 0.435 2230

2000 = 0.53 vt

Cac thong so cua may bien ap t ngau 63 MVA:

Sm(MVA)

in p (kV) UN% I0% P0(kW)

PN (kW)


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TONG QUAN CHNG 1



230 121 38.5 11 35 220.5 45

400 220 240

- S o thay the ien khang:

- Ta co:o ien khang cuon cao cua may bien ap t ngau:

%.CNU = 2

1

+

%.

%.%

.THNCHN

CTN

UUU =

21

+

5,0

22

5,0

3511 = 18.5%

xC =100

%.CNU .

dm

cb

S

S =100

5.18 .63

2000 = 5.87 vt

o ien khang cuon trung cua may bien ap t ngau:%

.TNU = 21

+

%.

%.%

.CHNTHN

CTN

UUU =

21

+

5,0

35

5,0

2211 = 0

xT =100

%.TNU .

dm

cb

S

S =100

0 .63

2000 = 0

220KV

HTX =0,35

CX =5.87

TX =0

110KV

HX =16.35

22KV

dX =0.53dX =0.53

CX =5.87

TX =0

HX =16.35

1N

2N

3N


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TONG QUAN CHNG 1


XHT

Xd Xd

N1

o ien khang cuon ha cua may bien ap t ngau:%

.HNU = 21

+ %.

%.

%.

CTNCHNTHN U

UU

=

21

+ 11

5,035

5,022 = 51.5 %

xH =100

%.HNU .

dm

cb

SS =

1005.51 .

632000 = 16.35 vt

- Ngan mach tai N1:o ien khang tng ng tnh en iem ngan mach:

1Nx = xHT +

2

1 .xd = 0.35 +2

10.53 = 0.615 vt

o Dong ien ngan mach sieu qua o:cbNI

1

=1

1

Nx

=615.0

1 = 1.626

1NI = cbNI 1 .Icb1 = 1.626 5.02 = 8.16 kA

o Dong xung kch:ixk1 = 2 kxk 1NI , vi kxk = 1.8 la he so xung kch.

ixk1 = 2 1.8 8.16 = 20.77 kA.

- Ngan mach tai N2:o ien khang tng ng tnh en iem ngan mach:

2Nx = xHT +

21 .xd +

21 .(xC + xT)

= 0.35 +2

10.53 +

2

1(5.87 + 0) = 3.550 vt

o Dong ien ngan mach sieu qua o:cbNI 2 =

2

1

Nx=

550.31 = 0.282

2NI = cbNI 2 .Icb2 = 0.2829.54 = 2.69 kA

o Dong xung kch:ixk2 = 2 kxk 2NI , vi kxk = 1.8 la he so xung kch.

ixk2 = 2 1.82.69 = 6.85 kA.

- Ngan mach tai N3:

XHT

XC XC

XT XT

Xd Xd

N2


41/67

TONG QUAN CHNG 1


o ien khang tng ng tnh en iem ngan mach:3N

x = xHT +2

1 .xd +2

1 .(xC + xH)

= 0.35 + 210.53 + 2

1(5.87 + 16.35) = 11.73 vt

o Dong ien ngan mach sieu qua o:cbNI 3

=3

1

Nx

=73.11

1 = 0.085

3NI = cbNI 3 .Icb3 = 0.085 29.99 = 2.55 kA

o Dong xung kch:ixk3 = 2 kxk. 3NI , vi kxk = 1.8 la he so xung kch.

ixk3 = 2 1.8 2.55 = 6.49 kA.

Tnh toan ngan mach cap ien ap 0.4 KV:

Do Smax.td = 500 kVA, nen ta chon may bien ap TG5844 G co thong so:

Sm(kVA)

Um.C(kV)

U m.H(kV)

UN(%)

P0(W)

PN(W)

Trnglng(kg)

630 24 0.4 6 1600 6300 2440

- ien tr RB cua may bien ap t dung:RB =

)(

10)()(2m

32

KVAS

KVUWP

B

mN =

2

32

630104.06300 = 2.54 (m ).

- ien khang XB cua may bien ap t dung:

Ta c XB =mB

mx

SUU

32

10%10

Vi Ux% = 2R2

N %)U(%)U( =22 16 = 5.92

UR% =)(10

)(

KVAS

WP

mB

N

=63010

6300

= 1

XHT

XC XC

XH XH

Xd Xd

N3


42/67

TONG QUAN CHNG 1


XB =mB

mx

S

UU32 10%10 =

630

104.092.510 32 = 15.03 (m ).

Zt = 2B2B )X()R( + = 22 03.1554.2 + = 15.24 (m ).Tong tr hai may bien ap t dung:

Z =2

Z t =2

24.15 = 7.62 (m ).

- Dong ien ngan mach tai ien ap 0.4 (kV):

IN(0.4 KV) =Z

Um

3=

62.73

400

= 30.31 (kA).

- Dong ien xung kch tai cap 0.4 KV:IXK = 2 KXK IN(0.4 KV) = 2 1.8 30.31 = 77.16 (kA)

Bang tong hp tnh toan dong ien ngan mach:

iem nganmach

Um (KV) IN (KA) IXK (KA)

N1 220 8.16 20.77N2 110 2.69 6.85N3 22 2.55 6.49

Cap 0.4 KV 0.4 30.31 77.16


43/67

TONG QUAN CHNG 1


CHNG 6

CHON KH CU IEN VA PHAN DAN IEN

6.1KHAI NIEM CHUNG

e van hanh c tram bien ap, ngoai thiet b chnh la may bien ap con can cocac kh cu ien va cac phan dan ien. Can c vao nhiem vu, chc nang cua cac khcu ien co the phan thanh cac loai sau ay:

6.1.1 Cac kh cu ien:6.1.1.1 Cac kh cu ien ong m:

1.May cat: la kh cu ien dung e ong cat mot phan t cua he thong ien nhmay bien ap, ng day v.v trong luc lam viec bnh thng cung nh khi co s co(ngan mach).

2.Dao cach ly: la kh cu ien co nhiem vu tao mot khoang cach trong thayc e am bao an toan khi sa cha may bien ap, may cat, ng day, Daocach ly ch ong cat khi khong co dong hoac co dong nho, ien ap khong cao lam.

3.May cat tai: la kh cu ien ch ong cat c dong ien trong che o lamviec bnh thng, khong co kha nang ong cat c dong ngan mach, s dung cap 24 kV tr lai.

4.Cau ch: la kh cu ien e cat mach ien khi ngan mach va khi qua tai, sdung cap 35 kV tr lai, mach n gian, khong quan trong.

5.Cau ch t ri: thc chat la cau ch nhng co cau tao ac biet, khi no catmach se cat luon dao cach ly (tren phan ong cua dao cach ly co gan ch).

6.Dao cach ly t ong:thc chat la dao cach ly nhng co the ong cat t ong.7.Dao ngan mach (dao at): la kh cu ien khong phai e ong cat mach ien

ma e noi mach ien xuong at, tao thanh ngan mach nhan tao khi can thiet.

6.1.1.2 Cac kh cu ien phuc vu cho o lng, t ong, bao ve relay:


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TONG QUAN CHNG 1


1. Bien dong: bien oi dong ien ln trong mach ien co ien ap cao ve dongien tng ng vi thiet b o lng, t ong, bao ve relay va cach ly vimang cao ap e am bao an toan cho ngi s dung, tieu chuan hoa cthiet b o lng,

2. Bien ien ap: bien oi ien ap cao ve ien ap thap tng ng, dung cho olng, t ong, bao ve relay,

6.1.1.3 Cac kh cu ien han che dong ien ngan mach (khang ien):

1. Khang ien n: thng at tren thanh gop va ng day.2. Khang ien kep: at tren ng day.

6.1.2 Phan dan ien:

Can c vao cau truc, phan dan ien c phan thanh:1. Day dan: la day mem, tiet dien tron co the dung mot hay nhieu si phu

thuoc vao dong ien, dung s treo, s e cach ly vi cac phan noi at.

2. Thanh dan: la thanh cng, tiet dien hnh ch nhat, hnh tru rong, hnh mang, co the dung mot hoac hai thanh ghep chat nhau phu thuoc vao dong ien,dung s e cach ly vi at.

3. Cap lc: la day dan mem c boc cach ien theo ien ap nh mc. Khilap at co the chon di at hoac at trong ranh (ham cap) khong can s

cach ien.6.2NHNG VAN E CHUNG CO LIEN QUAN EN TNH TOAN E CHON

CAC KH CU IEN VA PHAN DAN IEN

Khi van hanh, cac kh cu ien va phan dan ien eu phai chu c ien apcua mang ien, dong lam viec ln nhat chay qua lau dai, dong ngan mach chayqua trong thi gian ngan mach (ngan han). Cho nen khi tnh toan phai xet va kiemtra cac che o tren.

6.2.1 Cac che o lam viec cua mang ien:

6.2.1.1 Che o lau dai:

1. Che o bnh thng: la khi cac thiet b eu lam viec vi phu tai khong vtqua Smax.


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TONG QUAN CHNG 1


2. Che o qua tai: mot so kh cu ien va phan dan ien cho phep qua tai trongthi gian nhat nh, ac trng bi he so qua tai.

3. Che o cng bc: che o nay, neu trong s o co mot phan t phai nghcng bc th dong ien se phan phoi qua cac mach khac khi bnh thng.

6.2.1.2 Che o lam viec ngan han:

Dong ien rat ln nhng thi gian khong dai, tnh bang phut, giay. Nhiet phatnong cua cac phan t co dong chay qua cha at gia tr on nh. ac trng cua cheo nay la ngan mach, dong chay qua bang dong ngan mach IN va thi gian bangthi gian ton tai dong ngan mach tN (tN = tBV + tMC).

6.2.2 Tnh toan xung nhiet cua dong ngan mach:

Trong mot so kh cu ien co the cho kha nang chu ng ve mat phat nong khi

ngan mach bang tr so:

- Dong ien nhiet Inh vi thi gian cho phep tnh.- Xung nhiet cua dong ien ngan mach BN:Co 3 phng phap tnh xung nhiet BN phu thuoc vao phng phap tnh dong

ngan mach. Neu xac nh c dong ngan mach theo thi gian IN(t) th:

BN = t

NdtI

0

2 va tnh gan ung la: BN =

+ +i

iiT

II.

2

2)1(

2

, trong o:

o Ii la dong ien ngan mach tai thi iem ti.o Ti la thi oan t i en (i + 1)

Neu ngan mach xa th xem: IN = It = Io va thi gian tN < 0,02 sec

BN = I2(tN + TKCK), trong o:

o TKCK la thi gian ton tai cua thanh phan khong chu ky (thng la0,05 sec). Neu xet theo thi gian tng ng:

Tt = f

= N

od

tII ,'''' ; BN = I2o.Tt

* Cac ieu kien chung e chon kh cu va phan dan ien:

1. Ve ien ap:


46/67

TONG QUAN CHNG 1


Um.kc UHT

Trong o:

o Um.kc la ien ap nh mc cua kh cu ien.o UHT la ien ap ni at kh cu ien (rieng bien ien ap bat buoc

Um.kc= UHT).

Chon Um.kc> UHT noi chung la khong can thiet v nh vay se tang von au t,tr trng hp khong co thiet b cung cap ien ap.

2. Ve dong ien:Im.kc Icb.max

Trong o:

o Im.kc la dong ien nh mc cua kh cu ien.o Icb.max la dong cng bc i qua kh cu ien.

May bien ap va bien dong cho phep qua tai nen ieu kien tren se la:

Im.BI.kqt Icb.max, vi kqt la he so qua tai cho phep.

3. Kiem tra ve on nh nhiet:I2nh.tnh BN hoac BN.m BN

Trong o:

o BN la xung nhiet tnh toan.o Inh, tnh, BN.m la kha nang chu nhiet cua kh cu ien.

4. Kiem tra ve o on nh ong:Il.m.kc Ixkhoac il.m.kc ixk

Trong o: Il.m.kc, il.m.kc la kha nang chu ng ve lc ong ien theo trso hieu dung va tr so bien o.

Rieng oi vi vi thanh dan, ieu kien nay se la: ttcp

Trong o:

o tt la ng suat tnh toan khi co ngan mach.


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TONG QUAN CHNG 1


o cp la ng suat cho phep cua vat lieu che tao.Vi kh cu ien con co cac ieu kien rieng, nh may cat con them ieu kien

kha nang cat.

Icat.m.MC IVi bien dong, bien ien ap co them ieu kien cap chnh xac cua chung phai

tng ng vi cap chnh xac yeu cau cua phu tai:

Sm (cap chnh xac) Smax = dcS + Sd

Trong o:

o Sm (cap chnh xac) la cong suat nh mc tng ng vi cap chnh xac donha che tao cho.

o dcS - la tong cong suat cac dung cu noi vao bien dong, bien ienap.

o Sd la cong suat tieu thu tren day dan noi t bien dong hay bien ienap en dung cu o.

8.4CHON MAY CAT, DAO CACH LY CHO PHNG AN TOI U

6.3.1 May cat:

Phng an toi u c chon la phng an 1 (Dung 2 may bien ap t ngau

220/110/22 kV).May cat la kh cu ien dung e ong cat mot phan t cua he thong ien nh

may bien ap, ng day v.v trong luc lam viec bnh thng cung nh khi co s co(ngan mach).

Khi may cat ket hp vi thiet b relay bao ve se am bao cho he thong vanhanh tot, an toan cho ngi van hanh cung nh cho thiet b cua tram.

Yeu cau oi vi may cat:

- Cat nhanh, am bao khi ong cat khong gay chay no.- Co the ieu khien tai cho va t xa.- Co kha nang ong cat nhieu lan vi dong ien bnh thng va vi mot so lan

nhat nh vi dong ngan mach (do nha che tao quy nh).

- Co kha nang ong cat lap lai vi chu ky theo yeu cau.


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TONG QUAN CHNG 1


- Kch thc gon nhe.- Gia thanh ha.Ngoai cac thong so chung a neu tren trong thong so ky thuat cua may cat con

co dong ien cat nh mc Icat.m la dong ln nhat ma may cat co the cat machien.

oi vi may cat: qua trnh cat, phng phap, thi gian va kha nang dap tat hoquang khi cat dong ngan mach rat quan trong. Can c vao phng phap dap tat hoquang ta phan loai may cat ien nh sau:

- May cat nhieu dau.- May cat t dau.- May cat khong kh.- May cat kh.- May cat t sinh kh.- May cat chan khong.- May cat phu tai.

6.3.1.1 C s chon may cat:

1. ien ap nh mc cua may cat: Um UHT2. Dong ien nh mc cua may cat: Im Icb.max3. Dong ien cat nh mc: Icat.m IN (IN ladong ien ngan mach).4. Kiem tra on nh lc ong ien khi ngan mach: il.m ixk5. Kiem tra on nh nhiet: (Inh.m)2.tnh BN, trong o:

o Inh.m la dong ien on nh nhiet nh mc.o tnh la thi gian on nh nhiet nh mc.o BN la xung nhiet lng cua dong ien ngan mach.

- Thng th cung mot cap ien ap ta nen chon cung loai may cat, nhat lathiet b phan phoi vi cap ien ap t 35 kV tr len. Pha thiet b phan phoicap phu tai th ta nen chon may cat hp bo.

6.3.1.2 Chon may cat 220 kV:

La chon may cat theo cac ieu kien sau:

- ien ap nh mc cua may cat: Um 220 kV


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TONG QUAN CHNG 1


- Dong ien nh mc cua may cat: Im Icb.maxVi: Icb.max =

dm

tram

U

S

.3max. =

220.3

80.5 =0.21kA Im0.21 kA.

- Dong ien cat nh mc: Icat.m IN1 = 8.16 kA Icat.m 8.16 kA.- Kiem tra on nh lc ong ien: il.m ixk1 = 20.77 kA il.m 20.77 kA.

Khi may cat co Icat.m 1000A th khong can kiem tra on nh nhiet

Vay ta co the chon may cat sau:

Loai may catUm

(kV)

Im

(A)

Icat.m

(kA)

Il

(kA)

Inh

(kA)

tnh

(sec)

220-11-74 220 1250 40 50 50 3



- ien ap nh mc cua may cat: Um 110 kV- Dong ien nh mc cua may cat: Im Icb.max

Vi: Icb.max =dm

U

S

.3max110 =

110.3

50 = 0.26 kA Im 0.26 kA.

- Dong ien cat nh mc: Icat.m IN2 = 2.69 kA Icat.m 2.69 kA- Kiem tra on nh lc ong ien: il.m ixk2 = 6.85 kA il.m 6.85 kA


Loai may catUm

(kV)

Im

(A)

Icat.m

(kA)

Il

(kA)

Inh

(kA)

tnh

(sec)

110-23 110 1250 40 50 50 3



- ien ap nh mc cua may cat: Um 22 kV- Dong ien nh mc cua may cat: Im Icb.max


50/67

TONG QUAN CHNG 1


Vi: Icb.max =dm

U

S

.3max110 =

22.3

30 = 0.79 kA Im 0.79 kA.

- Dong ien cat nh mc: Icat.m IN3 = 2.55 kA Icat.m 2.55 kA- Kiem tra on nh lc ong ien: il.m ixk3 = 6.49 kA il.m 6.49 kA


Loai may catUm

(kV)

Im

(A)

Icat.m

(kA)

Il

(kA)

Inh

(kA)

tnh

(sec)

BMK-35 35 1000 16 45 16.5 4

6.3.2 Chon dao cach ly:

Dao cach ly la kh cu ien co nhiem vu tao mot khoang cach trong thay ce am bao an toan khi sa cha may bien ap, may cat, ng day... Trong khanang, dao cach ly cung co the ong cat mach ien trong mot so trng hp co giihan, nhng noi chung la ong cat khi khong co dong hoac dong nho, ien ap khongcao lam, sau khi may cat a cat mach ien

Dao cach ly co cau tao n gian khong co buong dap ho quang, chu yeu truyenong bang tay. Ta co cac loai dao cach ly sau:

- Dao cach ly at trong nha.- Dao cach ly at ngoai tri.- Dao cach ly khong co dao at.- Dao cach ly co mot hoac hai dao at.- Dao cach ly trong mat phang ngang, trong mat phang ng.- Dao cach ly kieu mot s (kieu treo), kieu thong thng.

6.3.2.1 Cac ieu kien chon dao cach ly:

1. ien ap nh mc cua dao cach ly: Um UHT2. Dong ien nh mc cua dao cach ly: Im Icb.max3. Kiem tra on nh lc ong ien khi ngan mach: il.m ixk4. Kiem tra on nh nhiet: (Inh.m)2.tnh BN, trong o:

o Inh.m la dong ien on nh nhiet nh mc.o tnh la thi gian on nh nhiet nh mc.


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TONG QUAN CHNG 1


o BN la xung nhiet lng cua dong ien ngan mach.Thng th cung mot cap ien ap ta nen chon cung loai dao cach ly, nhat

la thiet b phan phoi vi cap ien ap t 35 kV tr len. Pha thiet b phan phoi capphu tai th ta nen chon may cat hop bo, dang xe ay chang han, khi cat may catxong, keo may cat ra la tng ng cat dao cach ly.

6.3.2.2 Chon dao cach ly 220 kV:

La chon dao cach ly co cac thong so nh sau:

- ien ap nh mc cua dao cach ly: Um 220 kV- Dong ien nh mc cua dao cach ly: Im Icb.max

Vi: Icb.max =dm

tram

U

S

.3max. =

220.3

80.5 = 0.21 kA Im 0.21 kA.

- Kiem tra on nh lc ong ien: il.m ixk1 = 20.77 kA il.m 20.77 kA.Vay ta co the chon dao cach ly sau:

Loai Um

(kV)

Im

(A)

Inh

(kA)

tnh

(sec)

Il

(kA)

PH31,2 220 630 40 3 100

6.3.2.3 Chon dao cach ly 110 kV:La chon dao cach ly co cac thong so nh sau:


Vi: Icb.max =dm

U

S

.3max110 =

110.3

50 = 0.26 kA Im 0.26 kA.


Loai Um

(kV)

Im

(A)

Inh

(kA)

tnh

(sec)

Il

(kA)


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TONG QUAN CHNG 1


PH31,2 110 630 31,5 4 80

6.3.2.4 Chon dao cach ly 22 kV:

La chon dao cach ly co cac thong so nh sau:


Vi: Icb.max =dm

U

S

.3max110 =

22.3

30 = 0.79 kA Im 0.79 kA.


Loai Um

(kV)

Im

(A)

Inh

(kA)

tnh

(sec)

Il

(kA)

PB-35 35 1000 31,5 4 80

6.4 CHON THANH DAN THANH GOP

Trong tram bien ap, may bien ap cung vi cac kh cu ien (may cat, dao cachly,...) c noi vi nhau bang thanh dan, thanh gop va cap ien lc. Thanh dan,

thanh gop co hai loai chnh:- Thanh dan cng: thng dung lam thanh gop di 35 kV cac tram bien ap,

oan t thiet b phan phoi en may bien ap t dung.

- Thanh dan mem (day dan): thng dung e lam thanh dan cho thiet b ngoaitri vi ien ap t 35 kV tr len.

1. Thanh dan - thanh gop n tiet dien hnh ch nhat:a. Kiem tra dong ien cho phep: Icp = Icp.K1.K2.K3 Icb.max

Trong o:

o Icp la dong cho phep khi nhiet o cho phep la 70 0C va nhiet o moitrng xung quanh la 250C, thanh dan at ng.

o K1 = 0.95 la he so hieu chnh khi thanh dan at nam ngang.o K2 = 0.88 la he so hieu chnh theo moi trng xung quanh.


53/67

TONG QUAN CHNG 1


o K3 = 1 l s thanh gpNhiet o moi trng xung quanh (0C) 10 15 20 25 30 35 40 45

K2 1,15 1,10 1,05 1 0,94 0,88 0,82 0,75

b. Kiem tra ieu kien on nh nhiet:- Khi a chon thanh dan theo ieu kien bnh thng co the kiem tra ieu kien

on nh nhiet theo bieu thc: Schon Smin =NB

C

Trong o:

o C la he so phu thuoc vao vat lieu thanh dan, CCu = 171; CAl = 88o BN la xung nhiet tnh toan: BN = I2N.tnm, IN tnh bang A.

c. Kiem tra ieu kien on nh lc ong ien:- Theo tieu chuan o ben c, ng suat cua vat lieu thanh dan khong c ln

hn ng suat cho phep cua no: ttcp

Trong o:

o cp la ng suat cho phep cua vat lieu thanh dan, cp Cu = 1400 KG/cm2; cp Al = 700 KG/cm2

o tt la ng suat tnh toan khi ngan mach, xac nh nh sau: Lc ong ien Ftt tac ong len thanh dan khi ngan mach oi vi

pha gia :

Ftt = 1,76.10-8.a

l . i2xk (KG)

Trong o:

ixk la dong ngan mach xung kch ba pha (A). l la khoang cach gia hai s thanh dan lien nhau

cua mot pha (cm).

a la khoang cach gia cac pha (cm). Moment uon M tac ong len thanh dan:

M = ttF .l

10(KG.cm)


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TONG QUAN CHNG 1


ng suat tnh toan tt xac nh theo bieu thc: tt =

M

W(KG/cm2)

Trong o: M la moment tac ong len thanh dan. W la moment chong uon cua thanh dan oi vi truc

thang goc vi phng cua lc tac dung (cm3), neu chon thanhdan n at thang ng th:

W = 0,17hb2

o Ghi chu: Neu phai xac nh khoang vt gia hai s thanh dan cothe kiem tra theo bieu thc: l lmax =

f

W cp10 (cm)

Trong o:

f la lc ong ien tren mot n v chieu dai 1 cm:f = 1,76.10-8.

a

1 . i2xk (KG/cm)

2. Chon day dan:- Day dan ien cho cac ho tieu thu xa phai c chon theo cac ieu kien:

a. Theo dong ien cho phep lau dai: Icp.K1.K2 Icb.maxTrong o:

o Icp la dong cho phep khi nhiet o cho phep la 70 0C va nhiet o moitrng xung quanh la 250C.

o K1, K2 la cac he so hieu chnh tng t khi chon thanh dan n.b. Theo mat o kinh te cua dong ien:

Skt =kt

bt

j

I max.

Trong o:o Ibt.max la dong ien bnh thng cc ai, (A).o jkt la mat o kinh te cua dong ien, (A/mm2).

c. Theo ieu kien vang quang: Uvq UHT


55/67

TONG QUAN CHNG 1


Trong o:

o UHT la ien ap nh mc ni at day dan.o Uvq la ien ap phat sinh vang quang, neu day dan ba pha c at

tren ba nh tam giac eu th co the tnh:Uvq = 84.m.r.lg

a

r(kV)

Trong o:

o m la he so xet en o xu x cua be mat day dan. m = 0.93 0.98: vi day dan ch co mot si. m = 0.83 0.87: vi day dan gom nhieu si ben lai .

o r la ban knh ngoai day dan (cm).o a la khoang cach gia cac truc day dan (cm).

Neu cac pha c bo tr trong mat phang ngang th co the xac nh theo bieuthc tren nhng giam i 4% oi vi pha gia va tang 6% oi vi pha ngoai.

Uvq.pha gia = 96%.Uvq; Uvq.pha ngoai = 106%. Uvq

e tranh hien tng vang quang, chon day dan pha cao ap sao cho:

Uvq > Um

d. Kiem tra day dan theo ieu kien on nh nhiet:- Khi a chon day dan theo ieu kien bnh thng co the kiem tra ieu kien

on nh nhiet theo bieu thc: Schon Smin =NB

C

Trong o:

o C la he so phu thuoc vao vat lieu day dan, CCu = 171; CAl = 88o BN la xung nhiet tnh toan: BN = I2N.tnm vi IN tnh bang A.

6.4.1 Chon thanh gop 220 kV:

-

Theo dong cho phep luc lam viec cng bc: Icp.K1.K2.K3 Icb.maxo Dong ien cng bc c tnh khi mot thanh gop 220 kV truyen tai

toan bo cong suat cua tram:

Icb.max =dm

tram

U

S

.3max. =

220.3

80,5 = 0.21 kA Icp321

max.

KKK

Icb =188.095.0

0.21

= 0.25 kA.


56/67

TONG QUAN CHNG 1


- Kiem tra on nh nhiet khi ngan mach: Schon Smin = NBC

BN = I2

N1. tnm = 8.162. 0.12 = 7.99 kA2s

Schon887.99 . 103 = 32.12 mm2

(Chon tnm = 0,12s; CAl = 88)

o Ta chon thanh gop la day nhom loi thep co cac thong so sau:

Tiet dien (mm2

) ng knh (mm)Utg(kV)

Tiet dienchuan Nhom Thep Day dan Loi thep

Icp(A)

220 300 204 298 204 29,2 18,6 690

- Kiem tra ieu kien vang quang:Uvq = 84mr lg

a

r= 840.851.46lg

46.1400 = 254.12 kV

(Chon: m = 0.85; a = 400 cm; vi r = 29.2/2 = 14.6 mm = 1.46 cm)

o Vi ba thanh gop at trong mat phang ngang th:Uvq pha gia = 96%Uvq = 0.96254.12 = 243.95 kV Um = 220 kV.

Nh vay thanh gop c chon nh tren la hp ly.

6.4.2 Chon thanh gop 110 kV:

- Theo dong cho phep luc lam viec cng bc: Icp.K1.K2.K3 Icb.maxo Dong ien cng bc c tnh khi mot thanh gop 110 kV truyen tai

toan bo cong suat cua cac phu tai 110 kV:

Icb.max =dm

U

S

.3max110 =

110.3

50 = 0.26 kA Icp321

max.

KKK

Icb =

188.095.00.26

= 0.31 kA.



57/67

TONG QUAN CHNG 1


BN = I2

N2tnm = 2.6920.12 = 0.87 kA2s Schon

880.87 .103 = 10.60 mm2

(Chon tnm = 0,12s; CAl = 88)

oTa chon thanh gop la day nhom loi thep co cac thong so sau:

Tiet dien (mm2) ng knh (mm)Utg

(kV)

Tiet dien

chuan Nhom Thep Day dan Loi thep

Icp

(A)

110 150 19 148.0 18.8 16.8 5.5 445

- Kiem tra ieu kien vang quang:Uvq = 84mr lg

a

r

= 840.850.84lg

84.0

400= 160.60 kV

(Chon: m = 0.85; a = 400 cm; vi r = 16.8/2=8.4 mm =0.84 cm)

o Vi ba thanh gop at trong mat phang ngang th:Uvq pha gia = 96%Uvq = 0.96 160.60 = 154.18 kV Um = 110 kV.

- Nh vay thanh gop c chon nh tren la hp ly.6.4.3 Chon thanh gop 22 kV:

- Theo dong cho phep luc lam viec cng bc: Icp.K1.K2.K3 Icb.maxo

Dong ien cng bc c tnh khi mot thanh gop 22 kV truyen taitoan bo cong suat cua cac phu tai 22 kV:

Icb.max =dm

U

S

.3max110 =

22.3

30 = 0.79 kA Icp321

max.

KKK

Icb =

188.095.00.79

= 0.94 kA.


BN = I2

N3 tnm = 2.5520.12 = 0.78 kA2s Schon

880.78 .103 = 10.04 mm2

(Chon tnm = 0,12s; CAl = 88)o Ta chon thanh gop la day nhom loi thep co cac thong so sau:

Tiet dien (mm2) ng knh (mm)Utg

(kV)

Tiet dien

chuan Nhom Thep Day dan Loi thep

Icp

(A)


58/67

TONG QUAN CHNG 1


22 500 27 481 26.6 29.4 6.6 945

- Kiem tra ieu kien vang quang:Uvq = 84mr lg ar = 84

0.851.47 lg 47.1400 = 255.55 kV

(Chon: m = 0.85; a = 400 cm; vi r = 29.4/2=14.7 mm =1.47 cm)

o Vi ba thanh gop at trong mat phang ngang th:Uvq pha gia = 96%Uvq = 0.96 255.55 = 245.33 kV Um = 22 kV.

- Nh vay thanh gop c chon nh tren la hp ly.6.5 CHON MAY BIEN IEN AP (BU)

6.5.1 Bien ien ap:

- Bien ien ap co nhiem vu bien oi ien ap co tr so cao U1 (ien ap s cap)ve ien ap thap U2 (ien ap th cap) tng ng vi thiet b o lng va s dungtrong mach bao ve.

- Cac loai bien ien ap:o Bien ien ap kieu ba pha nam tru.o Bien ien ap kieu bac cap.o Bien ien ap kieu phan chia ien dung.

- u iem:o Tieu chuan hoa c viec che tao thiet b o lng va bao ve.o An toan cho ngi va thiet b.

6.5.2 C s chon bien ien ap:

Bien ien ap c chon theo cac ieu kien:

- Cap chnh xac theo dung cu co yeu cau cao nhat.- Ve ien ap: Um.BU = UHT- Ve cong suat: tong phu tai noi vao BU be hn cong suat nh mc BU

(Sm.BU) tng ng vi cap chnh xac: 2S Sm.BU.

Trong o:


59/67

TONG QUAN CHNG 1


o 2S la tong phu tai cua BU tnh bang VA gom ca cong suat tacdung P va cong suat phan khang Q:

2S = ( ) ( )22

+ dcdc QP

- Chon day dan t BU en cac dung cu o theo hai yeu cau:o Ton that ien ap (U) tren day dan khong c ln hn 0,5% ien ap

nh mc th cap.

o sut ap phan tram:U% =

pU

U

2

.100 =p

pdd

U

IR

2

2. .100 =p

dd

U

SR

22

2

.3

. .100

Trong o: U2p la ien ap pha th cap cua BU. I2p la dong ien pha chay trong cuon th cap BU. Rdd la ien tr day dan t BU en cac dung cu o:

Rdd =dd

tt

F

l

vi: Fdd la tiet dien day dan (mm2); - ien tr suat vat lieu lam

day dan (mm2

/m), (Cu = 0,0188 mm2

/m; Al = 0,0315 mm2

/m) Thng tnh ngc lai e xac nh tiet dien day dan:

Rdd100

5,0 . 2

22.3S

U p ma Fdd=dd

tt

R

l.

Fdd 22p

2

1,5.U

.100. Sltt

o am bao o ben ve c nh vi day dan BI (FCu 1,5 mm2; FAl 2,5mm

2

).- Chu y: Khac vi BI, tren moi thanh gop hoac moi phan oan cua thanh gop

ch at mot BU chung, cho nen phu tai cua no la tat ca dung cu o cua tat ca cacmach noi vao thanh gop hoac phan oan o tr mach may ien (neu co) co at BUrieng.


60/67

TONG QUAN CHNG 1


6.5.3 Chon bien ien ap cap 220 kV:

- ien ap nh mc: Um.BU = 220 kV.- Phu tai th cap BU:

STT Dung cu o Kieu Solng

Cong suat(VA)

Cos P(W) Q (Var)

1 Volt ke 762 1 9 1 92 Walt ke 722 1 10 1 103 Var ke 722/1 1 10 1 104 Watt ke t ghi 4377 1 10 0.8 8 65 Var ke t ghi 4377 1 10 0.8 8 66 Cong t tac dung CA3Y 1 1.75 1 1.757 Cong t phan

khang

CR3Y 1 1.75 1 1.75

8 Tan so ke 762 1 8 1 8Tong 60.5 56.5 12

- Tong phu tai th cap BU: 2S = 22 125.56 + = 57.76 VA S2m.BU 57.76 VA

- Ta chon BU co cac thong so sau:

ien ap nh mcKieu

U1m (kV) U2m (V)Cap chnh

xac

Cong suatnh mc

(VA)

VCU-245 220/ 3 100/ 3 0.5 150

- Chon day dan bang ong co chieu dai t BU en ong ho o la l = 100 mo Da vao ieu kien o sut ap < 0,5% chon tiet dien day:

Rdd100

5.0

. 22

2.3

S

U p

= 100

5.0

.

( )76.57

3100.32

Rdd 0.87

Ta chon day ong co Cu = 0.0175 (/km).

ma Sdd=dd

tt

R

l. Sdd0.87

1000175.0 = 2.01 mm2


61/67

TONG QUAN CHNG 1


o e am bao o ben c, chon day dan co tiet dien FCu 1.5 (mm2)Vay ta chon day ong

Tit din(mm2) ng knh (mm) in tr khi 200C

(r0) (/km)Khi lng (kg/km)

3.94 2.2 4.520 35

6.5.4 Chon may bien ien ap cap 110 kV:

- ien ap nh mc: Um.BU = 110 kV.- Phu tai th cap BU:

STT Dung cu o Kieu Solng

Cong suat(VA)

Cos P(W) Q (Var)

1 Volt ke 762 1 9 1 9

2 Walt ke 722 1 10 1 103 Var ke 722/1 1 10 1 104 Watt ke t ghi 4377 1 10 0.8 8 65 Var ke t ghi 4377 1 10 0.8 8 66 Cong t tac dung CA3Y 1 1.75 1 1.757 Cong t phan

khangCR3Y 1 1.75 1 1.75

8 Tan so ke 762 1 8 1 8Tong 60.5 56.5 12

- Tong phu tai th cap BU: 2S = 22 125.56 + = 57.76 VA S2m.BU57.76 VA

- Ta chon BU co cac thong so sau:ien ap nh mc

KieuU1m (kV) U2m (V)

Cap chnhxac

Cong suatnh mc

(VA)

VCU-123 110/ 3 100/ 3 0,5 150

- Chon day dan bang ong co chieu dai t BU en ong ho o la l = 100 mo Da vao ieu kien o sut ap < 0,5% chon tiet dien day:


62/67

TONG QUAN CHNG 1


Rdd100

5,0 . 2

22.3S

U p =100

5,0 . ( )76.57

3100.32

Rdd 0.87

ma Sdd=dd

tt

R

l. Sdd0.87

1000175.0 = 2.01 mm2

o e am bao o ben c, chon day dan co tiet dien FCu 1.5 (mm2)Vay ta chon day ong

Tit din(mm2) ng knh (mm) in tr khi 200C

(r0) (/km)Khi lng (kg/km)

3.94 2.2 4.520 35

6.5.5 Chon may bien ien ap cap 22 kV:

- Do tram 22 kV ta chon thiet b phan phoi hp bo (nha may che tao san tngmach bao gom ca thanh gop, may cat, dao cach ly, thiet b bao ve, o lng) nen takhong can chon bien ien ap cho cap ien ap nay.

6.6CHON BIEN DONG IEN (BI)

6.6.1 Bien dong ien:

- Bien dong la thiet b co nhiem vu bien oi dong ien co tr so cao I 1 (dongien s cap) trong mach ien co ien ap cao ve dong ien I2 (dong ien th cap) cotr so thch hp nh 1A, 5A, 10A e cung cap cho cac thiet b o lng hoac dung

trong t ong bao ve relay.- Cac loai bien dong ac biet:

o Bien dong kieu mot vong quan.o Bien dong kieu bac cap.o Bien dong th t khong.o Bien dong kieu bu.o

Bien dong kieu lap san.- u iem:

o Tieu chuan hoa c viec che tao thiet b o lng va bao ve.o An toan cho ngi va thiet b.


63/67

TONG QUAN CHNG 1


- ac iem: lam viec gan giong tnh trang ngan mach. Cam bien dong lamviec khong tai, noi tat cuon th cap trc khi thao tai ra khoi cuon th cap cua biendong e tranh hien tng qua ien ap.

6.6.2 C s chon bien dong:- Bien dong c chon theo cac ieu kien (rieng tng mach):

Um.BI UHT; Im.BI Icb.max; Z2m.BI Z2 R2

2 .kl.I1m ixk; (knh.Im)2.tnh BN; cap chnh xac

Trong o:

o Z2m.BI la phu tai nh mc theo tong tr tng ng vi cap chnh xaccao nhat cua tai noi vao BI. Phu tai nh mc cua BI co the theo VA hay

tng ng vi cap chnh xac, cap chnh xac cang cao, phu tai cang nho.

o kl la boi so on nh lc ong ien: kl =dm

ldd

I

I

1

o knh la boi so on nh nhiet: knh =dm

nh

I

I

1

- Neu khi bnh thng dong ien cc ai (Ibt.max) be hn 0,7Im th khi cngbc co the at en 1,2Im.

- Tong tr cua BI cung cap cho cac dung cu o xac nh theo pha ln nhat.Gom co tong tr cac dung cu o noi tiep va tong tr day dan t ni at BI en cacdung cu o.

Z2 = dcZ2 + Rdd Z2m.BI

Trong o:

o Zdd la tong tr day dan (thng ch tnh Rdd): Rdd =dd

tt

F

l , vi: Fdd

la tiet dien day dan (mm2); - ien tr suat vat lieu lam day dan (mm2/m).

(Cu = 0.0175 mm2/m)

o ltt la chieu dai tnh toan (m), phu thuoc vao cach noi day BI.- Thng tnh ngc e xac nh tiet dien day dan:


64/67

TONG QUAN CHNG 1


Rdd Z2m.BI - dcZ2 ma Fdd=dd

tt

R

l.

Fdd dcBIdmtt

ZZ

l

2.2

.

- e am bao o ben c, tiet dien cua day dan chon phai khong nho hn tr sosau:

o Day ong: FCu1,5 mm2o Day nhom: FAl2,5 mm2

- Neu co dung cu o ien nang (cong t), e am bao sai so ve ien ap ri(U) th dung:

o Day ong: FCu2,5 mm2o Day nhom: FAl4 mm2

- Cap chnh xac cua BI dung cho bao ve relay co yeu cau rieng va phu tai baove relay khong dung chung vi cuon th cap cua ong ho o.

6.6.3 Chon bien dong cap ien ap 220 kV:

Chon bien dong mac hnh Y, at tren ca 3 pha.

- ien ap nh mc cua BI: Um.BI 220 kV.- Dong ien nh mc s cap: Im.BI Icb.max

Vi: Icb.max =dm

tram

U

S

.3max. =

220.3

80.5 = 0.21 kA Im.BI 210 A

- Xac nh phu tai th cap BI:Phu tai (VA)Ten dung cu

Pha A Pha B Pha CAmpe ke 3 3 3Walt ke 5 0 5Var ke 5 0 5Walt ke t ghi 10 0 10Cong t Wh 0.525 0 0.525Var ke 0.275 0.55 0.275


65/67

TONG QUAN CHNG 1


Tong cong 23.8 3.55 23.8

- Pha A va C mang tai nhieu nhat S = 23.8 VA nen chon lam phu tai tnh toan.- Tong tr cac dung cu o lng: dcZ2 =

BIdmI

S

.2

2 = 25

23.8 = 0.95

- V: Rdd + dcZ2 Z2m.BI nen toi thieu Z2m.BI phai ln hn 0.95 - T nhng yeu cau tren, ta chon bien dong co cac thong so nh sau:

Im (A)Kieu BI

Um(kV)

S cap Th cap

Capchnh xac

Z2m( )

Il(kA)

Inh/tnh

(kA/s)

T3M220B- 220 300 5 0.5 1.2 25 9.8/3

- Chon day dan bang ong co chieu dai t BI en ong ho o la l = 100 mo Rdd Z2m.BI - dcZ2 = 1,2 0.95 = 0.25

ma Fdd=dd

tt

R

l. Fdd25.0

1000175,0 = 7 mm2.

- Kiem tra on nh lc ong ien: 2 Il = 2 25 =35.36 kA > ixk = 20.77 kA.- Kiem tra on nh nhiet: I2nh.tnh BN

I2nh.tnh = 9.823 =288.12 kA2s > BN = 8.16

2 0.12 = 7.99 kA2s

Vay bien dong ta chon la hp ly.6.6.4 Chon bien dong cap ien ap 110 kV:

- ien ap nh mc cua BI: Um.BI 110 kV.- Dong ien nh mc s cap: Im.BI Icb.max

Vi: Icb.max =dm

U

S

.3max110 =

110.3

50 = 0.26 A Im.BI 260 A

- Xac nh phu tai th cap BI:Phu tai (VA)Ten dung cu Pha A Pha B Pha C

Ampe ke 3 3 3Walt ke 5 0 5Var ke 5 0 5


66/67

TONG QUAN CHNG 1


Walt ke t ghi 10 0 10Cong t Wh 0.525 0 0.525Var ke 0.275 0.55 0.275Tong cong 23.8 3.55 23.8

- Pha A va C mang tai nhieu nhat S = 23.8 VA nen chon lam phu tai tnh toan.- Tong tr cac dung cu o lng: dcZ2 =

BIdmI

S

.22 = 25

23.8 = 0.95

- V: Rdd + dcZ2 Z2m.BI nen toi thieu Z2m.BI phai ln hn 0.95 - T nhng yeu cau tren, ta chon bien dong co cac thong so nh sau:

Im (A)Kieu BI

Um(kV)

S cap Th cap

Capchnh xac

Z2m( )

Il(kA)

Inh/tnh

(kA/s)

T3M110B- 110 400 5 0.5 1.2 84 16/3

- Chon day dan bang ong co chieu dai t BI en ong ho o la l = 100 mo Rdd Z2m.BI - dcZ2 = 1.2 0.95 = 0.25

ma Fdd=dd

tt

R

l. Fdd25.0

1000175,0 = 7 mm2.

- Kiem tra on nh lc ong ien: 2 Il = 2 84 =118.79 kA> ixk = 6.85 kA.- Kiem tra on nh nhiet: I2nh.tnh BN

I2nh.tnh = 1623 = 768 kA2s > BN = 2.69

2 0.12 = 0.87 kA2s

Vay bien dong ta chon la hp ly.

6.6.5 Chon bien dong cap ien ap 22 kV:

- Do tram 22 kV ta chon thiet b phan phoi hp bo (nha may che tao san tngmach bao gom ca thanh gop, may cat, dao cach ly, thiet b bao ve, o lng) nen takhong can chon bien dong cho cap ien ap nay.


67/67

TONG QUAN CHNG 1

-

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