Unlocktai Lieu Chuyen de HCác điều kiện hòa đồng bộ MFĐ vào lưới1. Cùng tần số...

8/10/2019 Unlocktai Lieu Chuyen de HCc iu kin ha ng b MF vo li1. Cng tn s 2. Cng in p3 .Cng t t

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Ti liu o to chuyn Hthng rle bo vtrong trm bin p - Phn nng cao

MC LC

Trang

Mc lc 1

Danh mc cc chvit tt 5

Chng I. Tng quan vrle kthut sdo hng Siemens chto 6

I.1. c im ca rle kthut sdo hang SIEMENS chto 6

I.1.1. c im ca rle kthut sdo hng SIEMENS ch

to

6

I.1.2 Gii thiu phn mm DIGSI 9I.2. Gii thiu vrle bo vso lch my bin p 7UT6xx 9

I.2.1. Gii thiu chung v r le so lch my bin p h

7UT6xx

9

I.2.2. Phm vi sdng 10

I.2.3. Cc btham sci t 11

I.2.4. Chc nng bo vso lch 12

I.2.5. Chc nng bo v chng chm t hn ch 87N

(Restricted Earth Fault-REF)

23

I.2.6. Chc nng bo vqua dng pha/ qu dng chm t 24

I.2.7. Bo v chng qu ti nhit (Thermal Overload

Protection - 49)

27

I.2.8. Bo v chng qu t thng li thp

(OverexcitationProtection- 24)

29

I.2.9. Bo v chng hin tng my ct t chi tc ng

(Circuit Breaker Failure Protection - 50BF)

30

I.2.10. Chc nng gim st trong rle 31

I.3. Gii thiu vrle bo vmy pht in 7UM62x 37

I.3.1. Gii thiu chung vbo vmy pht in 37

Thc hin ti: Cng tyin lc Du kh C Mau - Nm: 2011Bin son: Cng ty P&3T Email: [email protected] Homepage: http://www.p-3t.com

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I.4.3. Chc nng pht hin dao ng in (21 & 21N) 69

I.4.4. Chc nng pht hin ngun yu hoc mmy ct u

i din (Weak Infeed or Breaker open condition)

70

I.4.5. Chc nng bo v qu dng (D phng hoc bo v

khn cp)

71

I.4.6. Chc nng chng ng vo im sc(SOTF - Switch

on to Fault)

71

I.4.7. Chc nng nh vsc 72

I.5. Gii thiu vrle bo vqu dng 7SJ62x 73

I.5.1. Gii thiu vrle kthut sh7SJ62 73I.5.2. Chc nng bo vqu dng 73

I.5.3. Chc nng bo vchng scchm t thong qua lp

li (Intermittent ground fault protection)

74

I.5.4. Chc nng nh vsc(Fault Location) 74

I.6. Gii thiu vrle bo vso lch thanh ci 7SS52x 75

I.6.1. Gii thiu vrle kthut sh7SS52x 75

I.6.2. Gii thut lm vic vi gi trtc thi ca dng in 77

I.6.3. Check Zone (Vng kim tra) 80

Chng II. Tnh ton cc thng sbo v 82

II.1. Tnh ton thng sci t cho rle qu dng in (I0>

hay 50& 51; 50N & 51N)

82

II.2. Tnh ton thng sci t cho rle khong cch (Z< hay

21)

85

II.3. Tnh ton thng sci t cho rle so lch (I hay 87) 97

Chng III. Ci t r le ca Siemens ch off line trn my

tnh101

III.1. Cc yu cu chung 101

III.2. Cc bc thc hin 102

III.3. Thay i cc gi trchnh nh ca rle 105


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DANH MC CC CHVIT TT

Di y l mt schvit tt thng hay sdng trong ti liu:

- CT: My bin dng in (Current Transformer)

- DT: c tnh c lp (Definite Time)

- EI: Cc kdc (Extremely Inverse)

- IT: c tnh thi gian phthuc (Inverse Time)

U ban K thut in Quc t (- IEC: International Electrotechnical

Commission)

- MBA: My bin p

- MF: My pht

- REF: Bo vchng chm t hn ch

- SI: Dc tiu chun (Standard Inverse)

- TTK: Thnh phn thtkhng

- TTN: Thnh phn thtnghch

- TTT: Thnh phn thtthun

- VI: Rt dc (Very Inverse)

- VT: My bin in p (Voltage Transformer)


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CHNG I. TNG QUAN VRLE KTHUT S

DO HNG SIEMENS CHTO

I.1. c im ca rle kthut sdo hang SIEMENS chto

I.1.1.c im ca rle kthut sdo hng SIEMENS chto

Cc rle kthut sca hng SIEMENS mang tn gi chung SIPROTEC p

ng ton din cc nhu cu bo vtrong hthng in. Cc thit bbo vlm vic

tin cy, giao din v phng thc truy cp thun tin ddng hn hu ht cc rle

ca cc hng khc. Phn mm DIGSI 4 l cng cmnh trgip cc kstrong

vic qun l, ci t v phn tch sc. Phn mm ny tng thch vi mi loi r

le ca SIEMENS.

Hnh 1.1. Trle ca hng SIEMENS

- Cc rle SIEMENS cn c cc c im ni bt sau:

+ Tch hp gia cc chc nng bo v, iu khin v o lng

+ C thla chn cc chun truyn thng theo tiu chun nhIEC 61850; IEC

60870-5-103; DNP 3, MODBUS v PROFIBUS.

+ C sn cc modul thit b truyn thng chuyn i nng cp ln chun

IEC 61850.+ SIEMENS l mt trong nhng nh sn xut tch cc trong vic htrchun

truyn thng quc tIEC 61850 v l nh sn xut u tin a ra cc thit bbo

vv tng ha trm tun ththeo chun ny. Ti cui nm 2007, khong 30,000

thit bbo vv tng ha trm ca SIEMENS trong gn 300 trm bin p

vn hnh da trn chun IEC 61850.

- Qu trnh pht trin ca cc thhrle SIEMENS:

SIEMENS l mt trong nhng nh sn xut hng u thgii trong lnh vc

thit bbo vrle, cc cng nghmi ca SIEMENS ng gp ng ksphttrin ca cc thhrle ni chung.


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+ Nm 1976: Cc rle da trn nn tng ca hthng my tnh mini c

SIEMENS chuyn giao cho khch hng v vn vn hnh ti tn thi im hin ti.

+ Tnm 1985: L nh sn xut u tin gii thiu cc dng rle kthut s

vi giao thc truyn tin c chun ha. Hin nay SIEMENS c khnng cung cp

rle bo vcho ton bcc thit btrong hthng in tbo vmy pht, thanh

gp cho ti cc ng c ca khch hng. Ti thi im hin ti khong 600,000

thit brle c chuyn giao cho khch hng.

- Cc c im cng nghu vit ca rle SIEMENS

+ Thit knhgn, tch hp nhiu chc nng trong mt thit bgim gi

thnh.

+ Khnng sn sng v tin cy cao do c khnng tgim st bn thn

trong qu trnh vn hnh ca thit bbo vrle.+ c tnh lm vic n nh, trnh c hin tng tri tham s, c tnh.

+ chnh xc o lng cao do p dng cc thut ton xl ti u v lc tn

hiu s.

+ Tch hp thm rt nhiu chc nng phkhc nhgim st ti, gim st mc

pht nng/gi ha, chc nng ghi sc, rle so lch vi chc nng nh vs

c, ...

+ Hthng bn phm v giao din trn rle c thit kti u cho ngi vn

hnh sdng.+ Ddng truy cp cc dliu trong rle bng my tnh thng qua cng ni

tip. C thtruy nhp txa hoc ti chty theo yu cu.

Hnh 0.2. Cc nhm ci t trong rle

+ Khnng tng thch cao vi cc trng thi vn hnh ca hthng: C th

ci t nhiu bs liu vo r le, qu trnh chuyn i gia cc bgi trci t

ny c thc thc hin do bn thn rle hoc thng qua cc tn hiu iu khintbn ngoi.


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- Phn loi cc rle SIEMENS

+ Hrle SIPROTEC 4: Bao gm cc r le bo vcho cp trung p ti ti

cp siu cao p (Bo vqu dng, so lch, khong cch, ...). Cc rle u l loi a

chc nng ddng ph hp vi cc iu kin cth.

Hnh 0.3. Mt rle thuc hSIPROTEC Compact

+ H r le SIPROTEC Compact: L loi c kch thc nhgn, chc nng

ca rle gn tng tnhcc rle thuc hSIPROTEC 4. Rle c thtruy nhp

qua cng USB pha trc mt, cc khi tn hiu vo dng v p l loi c ththo

lp c.


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+ Hrle SIPROTEC 600: Cc rle thuc hny c gi thnh hp l hn,

thch hp s dng trong cng nghip hoc cc cng ty in lc. Cc r le ny

thng khng tch hp nhiu chc nng nhcc hrle khc.

+ Hrle SIPROTEC Easy: Dng cho cc ng dng n gin, gi thnh hp

l. Qu trnh ci t thc hin bng cch gt cc cng tc la chn, khng yu cu

my tnh.

I.1.2 Gii thiu phn mm DIGSI

Vic truy cp r le c th thc hin thng qua phn mm DIGSI ca

SIEMENS, phn mm ny cho php ngi sdng c cc bn ghi, chnh sa v

chun bcc bgi trci t chon/off line. Ngoi ra phn mm cn c chc

nng xut cc gi trchnh nh sang nh dng ph hp vi thit bthnghim ca

hng Omicron.I.2. Gii thiu vrle bo vso lch my bin p 7UT6xx

I.2.1. Gii thiu chung vrle so lch my bin p h7UT6xx

Cu trc phn cng ca rle 7UT613/63x c minh ha trn hnh v1.4.

Hnh 1.4. Cu trc phn cng rle 7UT613/63x


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Rle c cc u vo tn hiu dng in IL1M1 IM3L3 dng cho mc ch

bo vso lch (o lng ti 3 vtr, mi vtr c 3 pha). Ngoi ra cn c thm 3

u vo tn hiu dng in ph, c thdng cho mc ch o dng in trn dy

trung tnh ca cun u sao, hoc dng cho cc bo vqu dng c nhy cao:

Pht hin dng r rt nh tvmy bin p xung t. Cc r le 7UT613/63x c

tht hng ring thm cc u vo in p phc vcho cc mc ch khc nh

pht hin hng tng qu tthng li tmy bin p (Bo vV/f).

u vo/ra nh phn (Binary input): Nhn tn hiu iu khin t bn ngoi/

xut tn hiu ct my ct, tn hiu lin ng ti u i din, ...

Giao din mt trc rle: Hin thcc thng tin o lng, cc thng tin cnh

bo v skin xy ra, trng thi ca thit b, ... Bn phm cho php truy cp cc

thng tin lu tr: Cc bn ghi sc, cc nhm ci t, thng svn hnh. Vi ccrle h7UT6 th c thcho php iu khin ng/ct my ct trc tip trle. R

le 7UT613 c mn hnh hin th4 dng, cn 7UT633 cho php hin thcsv

c kha iu khin mt trc.

Cc cng giao tip: Giao tip vi my tnh trc tip qua cng ni tip mt

trc rle thay i cc chnh nh (Dng phn mm DIGSI). Tt cdliu c

th truyn ti h thng iu khin trung tm qua cng SYSTEM INTERFACE.

Cng SERVICE INTERFACE cho php kt ni ti my tnh (Dng DIGSI) qua

modem hoc kt ni ti thit bo nhit (RTD box hay thermal box). Cng cnli dng cho vic ng bthi gian bng ng hGPS.

Hnh 1.5. Thit bRTD-box TR1200

Ngun cp cho rle c thl in p mt chiu hoc xoay chiu ty theo t

hng (24V 48V DC hoc 110250V AC).

I.2.2. Phm vi sdng

Hrle 7UT613/63x c thsdng bo vcho:


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- My bin p cc cp in p: Phm vi bo vc gii hn bi v tr cc

my bin dng, rle c trang bthut ton hiu chnh sdch pha do tu

dy my bin p gy ra. R le 7UT612 dng cho my bin p hai cun dy,

7UT613/633 dng cho cc my bin p ti 3 cun dy v 7UT635 dng cho my

bin p ti 5 cun dy.

- Cc ng c: Rle so snh dng in trung tnh cun dy u sao v dng

cc pha.

- Cun khng b ngang hoc b dc.

- Cc ng dy ngn v cc hthng thnh gp (T2-5 ngn l).

- Vi cc r le c trang bthm u vo in p: Phc vchc nng bo v

chng hin tng qu tthng ca li t(My bin p, cun khng).

- Chng nng bo v chng hin tng my ct t chi tc ng c th pdng cho 2 my ct, ngi dng c th ty la chn my ct no cn p dng

chc nng ny.

I.2.3. Cc btham sci t

Cc tham sci c thc chun bbng my tnh vi phn mm DIGSI sau

supload vo rle, thay i tham sci t trong rle bt buc phi vo mt

khu, y l mt chc nng m bo slm vic an ton ca rle.

Parameter Group Changeover Function: Tham sny cho php chuyn i

qua li gia cc nhm gi trci t (Ti a ti 4 nhm) lu trsn trong rle.a chci t 0103 Grp Chge OPTION vi hai ch: Enable (Disable): Cho

php (Khng cho php) chuyn i qua li kctrong qu trnh ang vn hnh.

Protected Object: y l mc m tvi tng c bo vbi chc nng

bo vso lch (Mt r le c thdng bo vso lch mt thit bchnh nhng

cng c th bo v thm cc phn t khc). a ch ci t 0105 PROT.

OBJECT vi cc la chn:

- PROT. OBJECT = 3 phase transf: i tng bo vl my bin p ba cun

dy.

- PROT. OBJECT = 1 phase transf: i tng bo v l my bin p mt

pha.

- PROT. OBJECT = Auto transf: i tng bo vl my bin p tngu,

chc nng ny cng p dng vi khng b ngang. Nu sdng 3 my bin p t

ngu loi mt pha ghp thnh hthng ba pha c ththc hin vic bo vso

lch cho tng my mt pha ring bit, khi gi trci t slPROT. OBJECT =

Aut tr.node.


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- PROT. OBJECT = Generator/Motor: Khi i tng bo v l my pht

hoc ng c.

- PROT. OBJECT = Busbar: Dng khi i tng bo v l cc h thng

thanh gp vi slng ngn lt hoc khi i tng l ng dy ngn (Khi nim

ng dy ngn y c hiu l ng vi di ca dy dn phkt ni tbin

dng hai u ng dy ti rle m khng gy qu ti cho bin dng).

I.2.4. Chc nng bo vso lch

y l chc nng bo vchnh ca rle, do

Bng 1.1. Bt/tt chc nng Bo vso lch

a ch Tham s Gi tr Din gii

0112 DIFF. PROT Enabled Bt chc nng bo vso lch

I.2.4.1. Nguyn l bo vso lch trong rle 7UT613/7UT63x

Bo vso lch so snh dng in i vo v i ra ca i tng c bo v.

Trong chvn hnh bnh thng hoc khi scngoi: Dng in chy vo v ra

khi i tng bng nhau bo vkhng tc ng. Khi xy ra sc trong vng

bo vth xy ra smt cn bng gia dng vo/ra khi i tng

bo vstcng.

Hnh 1.6. Nguyn l bo vso lch vi MBA hai/ba cun dy


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Bo vso lch c hm: Khi xy ra scngoi vng vi dng scln, do s

sai khc vc tnh tca cc BI cc pha ca i tng c bo v(Hnh 1.6)

nn khi xy ra hin tng bo ha li tBI c thgy ra dng khng cn bng ln

chy qua rle bo v, nu dng ny ln th rle c thtc ng mc d sc

khng xy ra trong vng bo v. khc phc hin tng ny, rle sdng thut

ton bo v so lch c hm (Xem thm phn din gii chi tit trong ti liu ca

chuyn Hthng rle bo vtrong trm bin p - Phn cbn).

Ty theo tng hng chto rle m cch la chn dng in hm c thkhc

nhau (Tuy nhin, ngha ca vic sdng dng in hm l khng thay i). Dng

hm c tc dng m bo s lm vic n nh tin cy ca r le chng li cc tc

ng khng mong mun, do cn c tn gi l dng n nh (IstabilityhayIstab). Vi

r le ca SIEMENS th dng so lch l tng vec tca cc dng in vo/ra itng trong khi dng hm c ly l 100% tng lnca cc dng ny, c

th 1 2diffI I I= +r r

v 1stab 2I I I= +r r

(V di vi bo vmy bin p hai cun dy).

iu kin rle tc ngl khi dng so lch ln hn mt slng phn

trm no ca dng hm: (diff restrain stab )I k I> trong krestrainl hshm, h

shm ny tng ng vi dc ca c tnh tc ng ca rle (Tham sSLOPE

trong bgi trci t). (V l do ny cc bo vso lch cn c tn gi ting Anh l

Percentage current differential protection)Xt slm vic ca rle (Tham kho h

Hnh 1.6. ):

- Chvn hnh bnh thng hoc khi scngoi:

Dng inI1i vo (Mang du dng), dng inI2i ra khi i tng (Qui

c mang du m), mt khc I1=I2, do : 1 2 1 2 0diffI I I I I= + = =r r

v

1 2 1 2 2stabI I I I I= + = + =

r r

1I Dng hm gp hai ln dng chy qua i tng,dng so lch xp xbng 0, do rle skhng tc ng.

- Chsctrong vng, githit dng scthai pha cp ti bng nhau:

Hai dng in scI1v I2bng nhau v cng hng vi i tng bo v

(u mang du dng), do 1 2 1 2 2diffI I I I I 1I= + = + = r r

v

1 2 1 2 2stabI I I I I= + = + = r r

1I dng so lch v dng hm bng nhau diff stabI I=

v bng tng dng ti im sc.- Chsctrong vng, ngun cp chtmt pha (Pha 1): Khi I2=0


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1 2 1 0diffI I I I= + = + =r r

1I v 1 2 1 0stabI I I I 1I= + = + =r r

dng so lch v

dng hm bng nhau diff stabI I= .

Nhvy, nu sdng thvi mt trc l dng hm ( stabI ) v mt trc l

dng so lch ( diffI ) th ta ca cc im ng vi sc trong vng snm trn

mt ng thng gc 450nhtrn hnh 1.7.

Hnh 1.7.c tnh tc ng ca rle v c tnh sc

Cn lu rng cc gi trci t vo r le l gi trtng iso vi dng

nh mc ca i tng c bo v(Tham sIN Obj).

I.2.4.2. c tnh tc ng ca rle

c tnh lm vic ca rle chia ra hai vng: Vng tc ng (Pha trn ng

c tnh tc ng) & vng kha (Pha di c tnh tc ng). Rle slin tc gim

st cc gi trIdiff&IStab, ng vi mi trng thi lm vic ca i tng sc mt

cp gi tr(Idiff;IStab) tng ng, nu ta ca im lm vic ny ri vo vng tc

ng th rle stc ng v ngc li nu ri vo vng kha.

L do c tnh tc ng ca rle c chia ra nhiu on: c tnh cchia ra nhiu on vi dc khc nhau vi mc ch m bo cho rle lm vic

chnh xc vi mi trng thi vn hnh ca i tng c bo v: Hm tt vi cc

scngoi vng v m bo nhy tc ng cao vi cc sctrong vng. Vi

cc rle cv rle tnh th vic chto c tnh vi nhiu on l rt kh khn, tuy

nhin vi rle sdo thc hin bng thut ton nn vic ny hon ton khthi.

Cc on c tnh ca r le c xc nh bng ta im u

(BASEPOINT) v dc tng ng (SLOPE - dc ca c tnh lm vic chnh

l i lng hshm krestrain trnh by phn gii thiu khi nim bo vsolch). Nh vy khi c tnh lm vic cng dc hn h s hm cng ln


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vng c tnh tc ng thu hp li, vng c tnh hm (Kha) mrng ra c th

hiu rng: khi rle sm bo tc ng hm tt hn chng li cc trng hp s

cngoi, tuy nhin vng tc ng thu hp cng c ngha l nhy tc ng ca r

le bgim i. Vn t ra l lm sao la chn c hshm thch hp m

boc chai yu t: {Hm tt&vn m bo nhy tc ng}. Thc tth

vic la chn hshm ny phi ty thuc vo i tng cthang c bo v.

rng: Vi cch xc nh dng hm bng tng i s dng vo/ra i

tng 1stab 2I I I= +r r

th khi dng ny tng ln sbiu thdng qua i tng cng

ang tng ln.

Hnh 1.8.c tnh tc ng ca rle 7UT6xx vi 4 phn on a, b, c & d

- Trng hp i tng bo vl my bin p(Tham kho thm phn cc yu

t nh hng n s lm vic ca bo v so lch my bin p trong ti liu ca

chuyn Hthng rle bo vtrong trm bin p - Phn cbn):

+ chlm vic bnh thng (Dng in cha vt qu dng nh mc):

Lun c mt dng so lch nh tn ti do sai sca cc BI, gi trkhi ng ca

on a phi t cao hn tng cc dng so lch ny, gi trkhi ng ny cn c tn

gi l dng so lch ngng thp I-DIFF> (a ch1221) tng ng vi on a ca

c tnh trn hnh 1.8. Khng cn thit phi hm trong vng ny tng nhy tc

ng, do hshm bng 0 (c tnh nm ngang, khng dc). Vi cc my bin

p c iu chnh u phn p th c thc thm dng so lch gy ra do vic chuyn

i u phn p. Nh sn xut khuyn co nn tng 10% gi trci t cho mi 10%


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ca phm vi iu chnh u phn p. V d, gi trci t l 0,2, nu my bin p c

di iu chnh phn p khong 10% th gi trci t cui cng l 0,22:

0 2 0 1 0 20 1IF

(%), ,

,D F

phamvi dieu chinh dau phan apI > = + ,

+ Khi dng qua i tng tng ln tip qu dng nh mc (Theo chiu tng

ca trcISTAB): Tng ng vi vic my bin p ang bqu ti, khi sai sca

cc BI bt u tng ln v dng so lch khi ny c thvt qu gi trci t ca

dng so lch ngng thp (I-DIFF>), rle c thtc ng nhm. Trng hp ny

phi s dng n dng hm hm bo v, on b ca c tnh tng ng vi

trng thi lm vic ny. on b c dc ngha l bt u c tc ng hm

mt mc no ty theo dc ci t.

on b xc nh theo:++ on ko di ca on b si qua gc ta (BASE POINT1)

++ dc ca on c tnh ny ny thng c ly theo kinh nghim ca

nh sn xut (Mc nh SLOPE1 = 0,25) - Tuy nhin trong qu trnh vn hnh nu

r le hay b tc ng nhm th c th t tng h s hm ( dc SLOPE1) ca

on c tnh ny.

+ Khi dng in qua i tng tip tc tng ln: Tng ng vi trng thi xy

ra scngoi vng bo v. Do dng scln, cc BI c thbbo ha vi mc

khc nhau kt qul dng so lch tng mnh - Tuy nhin do l scngoi nn

rle khng c php tc ng. m bo rle khng tc ng trong trng hp

ny bt buc phi tng tc ng hm on cca c tnh c sdng p

ng yu cu trong trng hp ny. dc ca on c ln hn ca on b tng

ng vi tc ng hm c tng ln. on c c xc nh theo ta im ko

di BASE POINT2 v dc SLOPE2, cc gi trny thng ly theo mc nh

ca nh sn xut.

+ on d: Xc nh vng lm vic ca r le trong trng hp s c trong

vng. Khi c sctrong vng th rle phi tc ng, tng nhy ca bo v

vi trng hp sctrong vng th khng cn phi c tc ng hm on d c

dc bng 0 (nm ngang). Do khng c tc ng hm nn on d chsdng vi


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sctrong vng bt buc phi xc nh chnh xc khi no th scc coi l

trong vng. Xt sn gin sau (Hnh 1.9) gm mt h thng (Qui i tng

ng vtrc my bin p) v mt my bin p:

Hnh 1.9. Stnh ton xc nh sctrong vng

Dng in sckhi xy ra ngn mch ba pha trong vng c thxc nh theo:

3 1( )N

hethong bienap

IX X

=+

. Trng hp cc oan nht vmt ln dng ngn mch l

khi my bin p c ni ti hthng c cng sut v cng ln Xhethong = 0,

khi : 31( )

N

bienap

I

X

= .

Trong hn vtng i vi cng sut cbn chn bng cng sut my bin

p th do %bienap k X U=&3 1( )

%N

k

IU

= . T cc tnh ton trn c th thy rng khi

dng in chy qua i tng c bo vln hn 31( )

%N

k

IU

= th chc chn sc

lc trong vng gi tr1

%k

Uny chnh l gi trci t vo rle xc

nh on dca c tnh.

Trong cc ti liu th gi tr ny c gi l dng so lch ngng cao I-

DIFF>>, gi trmc nh ca nh sn xut l 7,5 tng ng vi cc my bin p c

Uk% nhnht khong 13%, tuy nhin gi trny nn c tnh ton li cththeo

i tng c bo v, khng nn dng gi trmc nh.


17


19/131


- Trng hp i tng bo vl ng dy hay thanh gp

oi c thrt ln,

kh

y bin p

th tng

cao (

Bng 1.2. Chc nng ttng dng khi khi ng in cho i tng c bo v

Vi cc ng dy hoc thanh gp th dng ngn mch ng

xc nh c ln dng in khi bt u sctrong vng, trong trng

hp ny gi tr dng so lch ngng cao I-DIFF>> c tht ti v cng (Lun

lun sdng tc ng hm). Vi mt srle so lch chuyn bo vcho ng dy

th a phn c tnh tc ng thng c t phn on hn (Thng dng 2 phn

on tng tphn on a & b ca c tnh trnh by trn y).

- Trng hp c bit khc:ng choc hng c- m

Khi i tng c bo vc cp in, dng in khi ng c

c bit vi ng c) v trong mt strng hp c lm cho bo vso lch

tc ng nhm. khc phc hin tng ny th r le 7UT6xx c trang b thm

chc nng t ng tng dng khi ng ca r le khi bt u cp in cho itng. pht hin khi no cn kch hot chc nng ny vic gim st dng dng

hm. Bnh thng dng hm l tng ln ca dng vo/ra i tng dng hm

ln gp 2 ln dng bnh thng ca i tng (ng c), nu gi trdng hm o

c m nhhn gi trbnh thng ny th c thcoi l i tng cha c cp

in v khi chc nng tng dng khi ng sc kch hot. Khi chc nng

ny kch hot th ton bcc gi trci t ca cc on ca c tnh tc ng s

c tng ln theo mt tlty t START-FACTOR.

ng

a Gi tr/(McTham s Din gii

ch nh)

1205 INC.CHAR.START ON/OFF Bt/tt chc nng t ng

tng dng khi ng ca bo v

1251 I-REST. STARTUP0.002.00

Ngng pht hin ch

cha ng in (Do dng hm l

tng ln ca dng vo/ra

gi tr t 0,1 tng ng vi

ngng l 0,1/2=0,05 dng danh

nh ca i tng c bo

v).

I/InO/(0.1)

1252 START-FACTOR 1.0 2.0/(1) H s tng gi tr khi

ng cho mi on ca c tnh.


18


20/131


Lu : Dng khi ng ngng

cao khng b nh hng bi h

snhn ny. Vi cc ng ch

s ny c th t bng 2

(Khuyn co ca nh sn xut)

Thi gian chc nng tng

gi trkhi ng c hiu lc1253 T START MAX 0.0 180.0/(5 sec)

I.2.4.3. Xl dng in thtkhng khi thc hin b

Dng in thtkhng (TTK) c th gy ra tc ng nhm ca bo vi vi

c tnh) th dng

tht

I o dng in chy qua trung tnh cun dy u Y0hay khng. Xt

cc tr

h phn dng TTK chy vo bt ccun dy no khi c sc

chm

- My bin p c cun u sao, trung tnh ni t (Y ) v c sn BI trung tnh:

o vso lch

cc scchm t ngoi vng bo v. Vi cc thhrle c(Ho

khng c loi trbng cch sdng bin dng trung gian vi tu dy

thch hp: Nu cun dy my bin p u Y0th bin dng trung gian ca cun dy

c u theo stam gic loi thnh phn dng TTK chy vo pha nh

thvo rle. Tuy nhin khi sdng phng php ny th kcvi scchm t

trong vng th dng TTK vn bloi trv lm gim nhy ca bo v(C th

gim ti 1/3 do dng TTK c thchim 1/3 ln dng ngn mch khi chm t

mt pha N(1)).

Vi loi rle s7UT6xx th vic ny c xl linh hot hn rt nhiu tytheo vic c B

ng hp sau:

- My bin p c tu dy Y/; / hoc Y/Y (Trung tnh hai pha cch

in): Khng c thn

t ngoi vng rle khng cn phi thc hin thut ton xl dng TTK.

Hnh 1.10. My bin p c tu dy sao/tam gic

0


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Hnh 1.11. Phn bdng khi c scchm t ngoi

(BI trung tnh c sn)

vng

Khi xy ra scchm t in c thi vo trong cun Y0,

do c t BI trung tnh cun dy nn dng TTK qua trung tnh ny stcn bng

vi d

E1 DIFFw.IE5-MEAS = YES}

ton nhy ca bo vc thgim

~ 30%

n u lun c t u dy Y(N)y0, do vic c/khng loi tr dng TTK ty

thuc

2.4.4. Hm bsung

ngoi vng, dng

ng TTK trn cc pha bo v s khng tc ng nhm (Hnh 1.11.). u

im ca vic c BI trung tnh l dng TTK sc tloi trvi scngoi vkhi c sctrong vng bo vskhng phi loi trdng TTK sc nhy

cao hn.

s dng tnh nng ny cc a ch t 12111215 t l YES

{DIFFw.I

- My bin p c cun u Y0, khng c BI trung tnh:Trong trng hp ny

bt buc phi loi trdng TTK bng thut

do dng TTK c thm chim ti 1/3 dng sc(Khi scmt pha chm t

N(1)).- Cc kt lun trn hon ton tng tcho my bin p tngu:My bin p

t g

vo vic c t BI trung tinh hay khng.

Hnh 1.12. Vng hm bsung trn rle 7UT6xx

I. (Add-on Stabilization)


20


22/131


Vi cc hthng c dng in ngn mch ln mc bo ha ca cc BI

khc

c xc nh bi ngng dng hm I-ADD ON STAB

(a

Nguyn tc hot ng ca chc nng hm b sung: Khi xy ra s c ngn

mch

scxy ra (Chu ku tin): Dng sctng vt dng th

cp c

m xung n dng ngn mch

n

nhau dng so lch ln c thlm bo vtc ng nhm. Rle 7UT6xx s

dng sdng chc nng hm bsung ngn nga stc ng nhm ca bo v

khi xy ra scngoi vng.

Vng hm b sung

ch1261 - gi trmc nh l 4) v dc bng vi dc ca on c tnh b

(SLOPE1).

Hnh 1.13. Dng in thcp khi BI bbo ha

ngoi vng vi dng ngn mch ln, gi thit trng hp xu nht (Trnghp sgy ra dng so lch ln nht) l mt BI gn im ngn mch sbbo ha,

BI cn li hot ng tt. Din bin ca dng in pha thcp ca cc BI thhin

trn Hnh 1.13..

- Ngay khi

a hai BI tng tltheo. Sau BI pha thcp ca my bin p (Gn im

sc) bbo ha: dng in thcp do BI ny sinh ra bmo, nhn u (ng

mu vng cam), vi BI khng bbo ha dng in do n sinh ra vn l hnh sin

(ng mu hng m). Do c ssai lch vdng thcp gia hai BI xut hin

dng so lch vi bin ln (ng mu xanh l).

- Sau giai on qu ban u, dng scgi

nh (I ), khi cc BI c thkhng bbo ha na v dng so lch cng gim

dn.

- Theo phn tch trn, im lm vic ca r le s di chuyn theo qu o

ABC nhbiu din trn hnh 1.14. Ban u cha sc, dng so lch nh, dng

hm ln im lm vic l im A. Ngay khi scxy ra: dng hm tng, dngso lch cha tng, im lm vic di chuyn tAB, ri vo vng hm b sung.


21


23/131


Sau BI bbo ha: dng so lch tng vt ln im lm vic di chuyn tBC

v c thri vo vng tc ng ca rle.

Rle c trang bvng hm bsung skha stc ng ca rle khi im

lm v

vi tng pha, tuy nhin lnh kha

(Bloc

g hi khi ng xung kch my bin p (Harmonic Restraint)

my

h theo cc thnh phn sng hi c ththy

rng

so lch gm c:

Hnh 1.14. Sdi chuyn ca im lm vic khi c scngoi v bo ha BI

ic ri vo vng ny ngn chn slm vic sai. Ngc li, vi trng hp

s c trong vng xy ra th im lm vic lun di chuyn t A v ri lun vo

ng c tnh s c (Khng i qua vng hm b sung), r le s lun tc ng,

khng bkha. Thi gian hm bsung c hiu lc kha rle thng c ci ttnh theo chu kdng in tn s50Hz. Chc nng ny stng c gii trnu

im lm vic ri vo gn ng c tnh scv khng di chuyn trong khong

thi gian ln hn 1 chu k(im lm vic ri vo hoc gn c tnh sc& khng

di chuyn chng t c sctrong vng, cn phi v hiu chc nng hm b

sung rle c thhot ng bnh thng).

Chc nng hm b sung hot ng

king) rle c tha ra vi c3 pha, y l chc nng hm cho (CROSSB.

ADD ON) ca rle.

I.2.4.5. Hm theo sn

Chc nng hm theo sng hi chsdng c khi i tng c bo vl

bin p. Chc nng ny c sdng ngn chn vic tc ng nhm ca

bo vkhi ng xung kch my bin p. Chc nng ny khng c tc dng i vi

bo vso lch ngng cao (I-DIFF>>).

Khi phn tch dng tha xung kc

thnh phn sng hi bc 2 lun tn ti trong cc dng sng ca dng thaxung kch. Cc l do sdng thnh phn sng hi bc 2 (Bc chn) hm bo v


22


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- Dng tha xung kch (Qu ) lun cha thnh phn sng hi bc 2

- Dng sckhng cha thnh phn sng hi bc 2 v cc sng hi bc chn

nhin

dng

ny tng hm

bo v

ca my bin p c hnh dng khng ging nhau, rle c thtc ng nhm.Cc p

I.2.5.

i vi cc s c chm t c tn gi l bo v chng chm t hn ch

(Hnh

I.2.5.1. Nguyn l ho) Chbnh thng

- Dng tha chxc lp c thbmo sng do li tbo ha, tuy

ny cng khng cha cc thnh phn sng hi bc chn.

T c ththy rng, thnh phn sng hi bc 2 l c trng ring bit ca

dng tha xung kch sdng thnh phn sng hi bc 2

so lch khi ng khng ti my bin p. Hon ton tng tvi chc nng

hm bsung, c thsdng tnh nng hm cho vi chc nng hm theo sng hi.

I.2.4.6. Hm theo sng hi khi xy ra hin tng qu kch tli thp ca my bin

p.

Khi li t ca my bin p b qu kch t (Over-excitation), dng in cc

phahn tch cho thy rng, khi xy ra qu kch t, dng in bmo dng sng

th thnh phn sng hi tn ti chyu trong dng in lc ny l thnh phn bc l

3 & 5. Thnh phn sng hi bc 3 thng bloi tr trong my bin p (Do cun

u tam gic), nn thnh phn sng hi bc 5 thng c sdng.

Cc r le 7UT6xx c trang bchc nng hm theo ln ca thnh phn

sng hi bc 3 & 5 ny (a ch1207 RESTR. n.HARM).

Chc nng bo vchng chm t hn ch 87N (Restricted Earth Fault-

REF)

Chc nng ny p dng chbo vcc cun dy c trung tnh ni t trc

tip

1.15. ). iu kin bt buc l phi c BI o dng chy qua dy trung tnh ni

t ca cun dy, chc nng ny khng p dng i vi bo vthanh gp.

Hnh 1.15. Chc nng bo vchng chm t hn ch

t nga


23


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Khng c dng chy qua dy trung tnh v tng dng ba pha bng 0 dng

so lc ng 0 rle khng tc ng.

p, ty theo chni

t c K chy qua cc BI pha (ng nt t

trn h

c) Chs

ng in c gi trbng

nhau tng dng a vo rle bng 0 v rle skhng tc ng (Hnh 1.17. ).

I.2.5.

hng cn bng tpha

cc B

. Gii thiu

h TTK a vo rle b

b) Chscchm t trong vng

Sc dng TTK chy qua BI pha trung tnh my bin

a hthng c thc/khng c dng TT

nh 1.16). Dng in chy qua rle 87N l tng vector ca hai dng in ny,

mt khc hai dng in (Dng qua trung tnh v dng pha) c gc pha c thxp x

nhau dng qua rle c gi trln rle stc ng.

Hnh 1.16. Phn bdng khi c scchm t trong vng

cchm t ngoi vng

Hnh 1.17. Phn bdng khi c scchm t ngoi vng

D chy qua dy trung tnh v dng TTK trn ba pha

2. Nguyn l hm trong bo vchng chm t hn ch

Khi scpha-pha (Khng chm t xy ra), cc BI trn pha scc thb

bo ha khc vi BI trn pha cn li xut hin dng in k

I pha hin tng ny phn no tng tnhtrng hp sctrong vng.

Nu khng c bin php hm thch hp th rle c thtc ng nhm. Nguyn l

hm p dng trong bo vchng chm t hn chhon ton khc vi phng php

p dung trong bo vso lch 87T: vic hm sdng clnv gc phaca dng

in.I.2.6. Chc nng bo vqua dng pha/ qu dng chm t

I.2.6.1


24


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Chc nng bo v qu dng trong r le 7UT6xx l chc nng bo v d

i gian tc ng c thla chn l c tnh c lp DT, thi gian

tc

(SI): c tnh dc tiu chun c thsdng trong hu ht

cc tr y khng p ng c v

mt p

dc ng dy (Cn c bo v) thay i mnh khi im scgithit di

chuy

in. c tnh ny thch hp s dng vi cc

n

nh do cng sut ngn mch ca ngun thay i.

I.2.6.

Khi ng my ct bng tay, nu gp scth nn thc hin ct i tng cng

hanh cng tt. Ch ng tc bo vqu

dng

I.2.6.3. Kha bo vkhi ngxung kch my bin p

phng. c tnh th

ng khng phthuc vo ln dng sc(Definite Time) hoc c tnh ph

thuc IT (Inverse Time). c tnh thi gian ph thuc c th la chn theo tiu

chun IEC hay ANSI hoc ngi sdng c thtt c tnh tc ng theo yu

cu ca i tng c th(xem thm phn ti liu ca lp cbn vphng trnh

ca cc dng c tnh).

Phm vi khuyn co sdng ca cc loi c tnh:

- Standard Inverse

ng hp cn phi gia cc bo v, nu c tnh n

hi hp gia cc bo vth phi xem xt n cc c tnh tip theo nhVI hay

EI.- Very Inverse (VI): c tnh rt dc thch hp sdng khi ln dng in

sc

n tu ti cui ng dy.

- Extremely Inverse (EI): c tnh cc k dc c thi gian tc ng t l

nghch vi bnh phng ca dng

g dy mang cc ti c dng khi ng t bin thi im u v dnht

lnh, my bm, ng cln...c tnh ny cng thch hp phi hp vi cc cu

ch hoc cc thit btng li- Definite Time (DT): c tnh c lp thch hp sdng bo vcc ng

dy m dng ngn mch thay i m

2. Chc nng bo vkhi ng my ct bng tay

Hnh 1.18. Chc nng BV khi ng my ct bng tay

n c nng bo vkhi ng my ct bng tay t

bng cch tm thi t thi gian tc ng ca bo v qu dng v 0 giy.

Chc nng ny c kch hot da trn tn hiu tkha iu khin my ct a ti

u vo nhphn ca rle hoc khi c tn hiu ng my ct tbn thn rle pht

ra. Shnh 1.18 m tlogic hot ng ca chc nng ny.


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Hon ton tng tvi chc nng bo vso lch, nu bo vqu dng c

sdng pha ngun cp ti my bin p th cn phi c bin php kha bo v

kch ny c th tng ln gp

nhiu

i phti c cp in trli, tt ccc ti u khi ng, nu trong thnh

ng nhm. R le 7UT6xx c chc nng Dynamic Cold-load

Picku

ime, nu thi gian ngng cp in qu ngn th khng

cn t

ny khi ng xung kch my bin p do dng xung

ln dng danh nh. Chc nng hm bo vkhi ng xung kch my bin p

cng da trn t lca thnh phn sng hi bc 2 trong thnh phn dng in o

c.

I.2.6.4. Chc nng bo vkhi xy ra hin tng ti khi ng ng thi (Dynamic

Cold-load Pickup)

Kh

phn ti c cc ng cth dng in khi ng c thtng cao cc bo vqu

dng c th tc

p ngn nga tnh trng ny, chc nng ny p dng cho c bo v qudng pha & qu dng TTK.

Cchhot ng ca chc nng ny nhsau: khi pht hin ra ti (My ct)

bct ra th chc nng ny stng c kch hot (Sau khong thi gian ngng

cp in di CB Open T

hit phi kch hot chc nng ny do cc ti vn cn ang quay do qun tnh

nn dng mmy trli khng ln). Khi chc nng ny c kch hot n st

ng tng dng khi ng ca bo vln trnh hin tng tc ng nhm. Chc

nng ny stng c gii trsau mt khong thi gian nht nh, khi ccgi trkhi ng ca bo vstrvbnh thng. Thi gian gii trchc nng ny

c th tng c rt ngn nu dng o c gim di gi trkhi ng bnh

thng ca bo v.

Hnh 1.19. Chc nng Cold Load Pickup


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Hnh 1.19m tphng thc hot ng ca chc nng ny.

t im quan trng i vi chc nng ny l nguyn l pht hin khi no

ti b t in, c hai phng php c sdng trong rle 7UT6xx:

o nhphn ca r

le.

ct in.

I.2.6.

c 46)

tng u sai cc tnh my bin dng.

ng lm bo vdphng cho cc

bo v

ng scnhhn cdng khi ng ca bo v

qu d

ao. Chc nng ny c th p dng bo v cho bt c

n nht).

i

trn

bnh phng dng in

chy

M

c

- Sdng tip im phca my ct, a tn hin ti u v

- Gim st dng in chy qua i tng xc inh khi no ti b

5. Chc nng bo vqu dng thtnghch (Unbalaced Load Protection I2>

ho

Chc nng bo vny pht hin hng tng mt cn bng ti. Chc nng

ny cng c sdng pht hin tng mt pha ti ti, sc khng i xng

hoc hin

Dng thtnghch cn c sdng bo vchng qu ti (ng c) khixy ra hin tng mt cn bng.

Chc nng bo vqu dng TTN cn c d

qu dng pha, c bit vi trng hp s c hai pha. Khi s c hai pha

(N(2)), c thxy ra trng hp d

ng thng thng, khi cc bo vny skhng khi ng c, tuy nhin

do bo vqu dng TTN c dng khi ng rt b nn hon ton c nhy

pht hin cc scny.

I.2.7. Bo vchng qu ti nhit (Thermal Overload Protection - 49)Chc nng ny sdng bo vcc phn tca hthng in khi bqu

nhit khi dng ti tng c

cun dy no ca my bin p (Thng scho cun dy c cng sut l

Nguyn l hot ng: C 3 phng php c sdng trong r le 7UT6xx,

ngi sdng c thchn mt trong cc phng php ny.

a) Phng php hnh nh nhit khng tnh ti nh hng ca nhit m

g bn ngoi: Phng php ny coi cmy bin p l mt i tng ng nht,

dng in chy qua sgy ra mt nhit lng tng tlvi

qua i tng. Nhit lng ny s chia ra hai phn: mt phn ta nhit vo

mi trng, mt phn lm tng nhit ca bn thn i tng, tphn ca hai nhit

lng ny ph thuc vo phng thc lm mt, hnh dng, vt liu..ca i tng

c bo v. V d: vi cc my bin p nh, lm mt tnhin th phn nhit lng

ta ra mi trng schim phn nh, cn li sgy pht nng v ngc li vi my

bin p c h thng lm mt cng bc. Nh vy, nhit ca i tng tng

nhanh hay chm cng phthuc vo kt cu, hnh dng, lm mt, ... v n c ctrng bi mt hsgi l hng squn tnh nhit th (Hng sny c thtnh ton


27


29/131


c - qui trnh tnh ton c th hin chi tit trong hng dn s dng r le).

Trnh t tnh ton nhit s l: Bit dng in chy qua i tng tnh c

nhit lng ta ra bit th tnh c nhit c i tng.

Thc tdo khng bit nhit cthca i tng nn rle chc thtnhc tng nhitca i tng so vi nhit chun. Nhit chun y

c rle coi l nhit l nht cho phpng vi ti cho php

a

lin tc ln nht

ca m

n

y bin p. Phng trnh vi phn tnh ton tng nhit nhsau:2

1 1 1

th th Nobj

d

dt k I

+ =

Trong : - mc tng nhit so vi nhit chun ca i tng (Bao

nhiu % ca nhit cho php cui cng)k- hsthhin dng in ln lin tc ln nht cho php ca i tng, nu

khn

: cp cnh bo ng vi gi tr

g c thng s th c thly k=1,1.

tng nhit ca i tng tnh theo phng trnh trn s l mt hm m.

Chc nng ny thng c hai cp bo v alarm v cp

thhai ng vi end sct ti ca my bin p trnh hhng.

h n

n, ng quanh sc

kt

o, tuy nhin,

chs

hng thc bo v ny cng c hai

ng

b) Phng php hnh nh nhit c kti nh hng ca nhit mi trng

bn ngoi: Phng php ny da trn nguyn l ca phng php hn h nhit

n thun ktr im khc bit y l nhit mi trng xu

i trong phng trnh tnh ton tng nhit. Nhit mi trng xung quanh

(Thc ra l nhit ca mi cht lm mt) sc o bi cc cm bin, c tht

ti 12 im o v thng qua bRTD kt ni chuyn gi trvo rle, ngi sdng

sla chn nhit ca mt trong cc im ny a vo tnh ton.

c) Phng php da theo nhit im nng v c tnh ton tc gi ha

cch in: Phng php ny da vo thng tin do cc cm bin nhit t itng c bo va v. Rle 7UT6xx c thqun l ti 12 im

dng gi trca mt im o tnh ton mc qu ti v gi ha ca i

tng. Thng nhit ca mi cht lm mt pha trn gn mt my c s

dng do y l khu vc c nhit cao nht.

Rle sda vo phng thc lm mt ca my bin p, nhit cao nht ca

mi cht lm mt (Du my bin p), dng in chy qua cun dy tnh ton

nhit cun dy (Nhit theo C), p

ng nhit : cnh bo v tc ng.


28


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Tui thca cch in c tnh ton da theo nhit chun 980C, khi nhit

ca cun dy khc vi nhit ny th tui thca cch in cng thay i: nu

nhit

pht hin

, bo v

ny

dn n qu p)

ng nh

mc)

n tng qu tthng xy ra, li tkhng thmang thm tthng t

thng bt buc phi mc vng, tn qua cc kt cu kim loi ln cn gy pht nng

qu m

ng thng bo vvi c tnh

cao hn 980C th tui thcch in gim i v ngc li. Hrle 7UT6xx

tnh ton tc gi ha cch in da theo nhit thc to c. Tc gi ha

y l tsgia mc gi ha ti nhit ang tnh c v ti 980C. Tc

gi ha trung bnh thng c tnh trong mt khong thi gian no .

I.2.8. Bo vchng qu tthng li thp (OverexcitationProtection- 24)

Chc nng bo vchng qu kch thay qu tthng c nhim v

hin tng qu t thng trong li tca my pht in hoc my bin p

c sdng phbin vi cc my bin p theo sni bmy pht-my

bin p. Hin tng qu tthng li tc thxy ra khi:

- in p hthng btng cao (V d: My pht bmt ti t ngt, biuchnh kch tkhng vn hnh hoc tc phn ng chm

- Tn shthng gim thp (V d: Trong qu trnh khi ng tmy, tc

my pht tng dn dn, bkch t hot ng giin p u cc ng

Hnh 1.20.

Khi hi

c. sdng chc nng ny bt buc phi c tn hiu in p a vo rle,

in p dy ln nht trong ba pha sc sdng.

Do cc hin tng qu t thng qu khng gy nguy him nn vi hin

tng ny c thsdng bo vc trbo v. Th


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thi g

- 50BF)

cbhng.

bm thi gian ca chc nng 50BF}. trng

thi b

i cc bo vkhng da trn tn hiu dng in (Bo vqu tthng, bo v

Bucholz) th vic da t ct hay cha l khng

tin

Snguyn l ca chc nng 50BF c thhin trn hnh 1.21.

ian phthuc c sdng, bo vskhi ng khi tsV/f vt ngng

ci t.

I.2.9. Bo vchng hin tng my ct tchi tc ng (Circuit Breaker Failure

Protection

Chc nng bo vny m bo lun loi trc scmc nhanh nht

d my ct ti chs

Nguyn tc hot ng: Khi bt cbo v no tc ng sng thi gi tn

hiu n {My ct tng ng &

nh thng, my ct sct sau khong thi gian qui nh v dng in chy

qua i tng s b ct b m thi gian ca 50BF s tr v. Nu sau mt

khong thi gian m my ct khng c ct, dng in khng gim i th bm

thi gian ca 50BF stip tc m ht thi gian ci t, sau gi lnh ct timy ct cp trn ln cn.

Hnh 1.21. Snguyn l chc nng 50BF

V

rn dng in xc nh my ct

cy, trong cc trng hp rle c thsdng trng thi tip im phca

my ct. Cc r le h7UT6xx c thsdng chai cch gim st ny (Gim st

dng in hoc trng thi tip im ph).


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I.2.10. Chc nng gim st trong rle

Chc nng gim st trong rle bao gm: Gim st trng thi phn cng, hot

ng in, in

I.2.10

ic ca bvi xl. Chc nng ny cn gim st in p ca pin trong rle,

phn mm trong rle cng lin

tc

n tng mt i xng dng in thng

ca phn mm trong rle & Gim st cc i lng o c (Dng

p).

.1. Gim st phn cng & phn mm ca rle

Chc nng ny sgim st in p ca ngun nui rle v gim st in p

lm v

gim st shot ng ca bnh. Shot ng ca

c gim st, nu c hin tng bt thng xy ra th ton brle c ths

khi ng li. Nu sau 3 ln khi ng li (Trong vng 30 giy) m li phn mm

vn khng c gii trth rle sbkha.

I.2.10.2. Gim st mc i xng ca dng in & in p vn hnhchhot ng bnh thng, dng in 3 pha thng tng i i xng.

Rle c chc nng gim st v pht hin hi

minI

, nu gi trny nhhn ngng cho php th tqua i lngmax

Ing ng vi

y k

ng t, rl

in in p. chbnh thng, cun tam gic h

a pha cng a ra gi trtng

t. N

mch

ti 0 hoc khng ghi nhn c thi im dng in qua 0 l chdu

ca s

trng thi dng in pha ln nht lch qu mc so vi dng in pha nh

nht. Chc nng n hi hot ng sa ra tn hiu cnh bo Fail I balance.

Hon ton t e c chc nng gim st mc mt cn bng in p vi

cnh bo Fail U balance.I.2.10.3. Gim st mch in p tmy bin in p

Nguyn l: Chc nng ny so snh tng in p ba pha vi in p o c ti

cun tam gic hca my b

cung cp thnh phn in p TTK cn tng in p b

u hai gi tro lng ny lch nhau c vn trong mch in tmy bin

in p. Thng bo do rle a ra ng vi trng thi ny l Fail U Ph-E.

I.2.10.4. Gim st hin tng hmch dng do t dy

Khi xy ra hin tng hmch dng, bo vso lch c thhot ng nhm,

mt khc hmch dng ca CT c thgy ra hin tng qu p nguy him

nhth.

Nguyn l hot ng: chc nng ny lin tc gim st gi trtc thi ca dng

in, nu dng in thay i khc vi gi trmong mun v khi dng in suy gim

tc thi

c t dy mch dng CT. Chc nng ny ch hot ng c khi c

dng in qua rle (Thit b), trng hp t mch dng ng thi im dng inqua 0 th rle c thcng khng pht hin c.

I.2.10.5. Pht hin hin tng hmch p ca my bin in p (VT) - t cu ch


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Khi mch p bngn mch hoc hmch in p cp ti rle bst gim

cc chc nng bo vc dng n tn hiu in p c thbtc ng nhm (V

cho r

dng in

c

2.10.6. Pht hin hin tng ngn mch ba pha mch p

Chc nng ny i mch p v gy st

im in p cp vo rle. C thphn bit hin tng ngn mch mch p (Nh

n tng ny th dng in

o

bin ca dng in o c (Hoc tc tng dng

in

d: Bo vthp p, bo vda theo chiu cng sut). Chc nng ny chp dng

le 7UT613 & 7UT633 (Rle 7UT635 khng c u vo in p)

Nguyn l hot ng: Hin tng t cu ch gy mt p mch p c thpht

hin theo logic: {in p mt i xng & dng in vn i xng}. Smt i

xng ca in p c pht hin da theo ln ca in p TTN (U2),

gi thit l i xng nu dng TTN v TTK (I2& I0) nm di ngng cho

php. Tuy nhin nu trong qu trnh cc chc nng bo vda theo in p ang b

kha m thnh phn dng (I2& I0) vt ngng cho php th l chbo ca s

ctht v rle sgii trcc tn hiu kha ny v hot ng nhbnh thng. Hnh

1.22. m tchc nng gim st cu ch mch p ca rle.

Hnh 1.22. Chc nng gim st cu ch mch p

I.

pht hin hin tng ngn mch ba pha t

g

th) vi ngn mch pha scp (Nht th): Khi xy ra hi

c khng tng t bin.

Nguyn l: Bo vstc ng kha chc nng bo vda theo in p khi

- Tt cin p ba pha nhhn mt ngng cho php

- Khng c s tng t

nhhn mt mc cho php)


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- Dng in trn 3 pha ang ln hn mt ngng nhnht cho php (Chc

nng bo vkhong cch chxc nh c tng tr nu dng in ln hn mt

ng

p im phmy ct, dy ni, hng kp, ... nn rt phc tp, kt

hp v

(Khi mt in tip im

s

52a ca my ct

ang ng, 52b ang m, tip im rle bo vang mdng in gim st tn

ti v

ng cho php ti thiu no )

I.2.10.7. Gim st mch ct (Trang b cho r le 7UT613/63x) (Trip Circuit

Supervision - 74)

Do mch ct my ct nm ngoi rle v i qua nhiu khu: Cu ch, cu ni,

tip im rle, ti

mc quan trng ca vic ct my ct nn cn sdng chc nng gim st

mch ct ny. Ni mt cch khc, chc nng ny gim st sthng mch cho mch

ct ca my ct. Nu mch ct thng, sc mt dng in rt nhchy qua n, nu

mch ct bt, dng in ny smt rle scnh bo vscmch ct. Dng

in chy qua mch ct ny c tnh ton nh(CmA, v d1,4mA vi loi rle 7PA30 ca SIEMENS) khng lm cun ct tc ng.

Nguyn l hot ng ca chc nng ny nhsau: R le gim st c thbao

gm mt hoc hai rle phloi thng ng, ng chm

ng). Khi hai r le ny u tc ng (Mt in) th chc nng gim st c

kch hot v sa ra cnh bo.

Hnh 1.23. Phn bdng gim st khi my ct ng

- Khi my c t trng thi ng(Hnh 1.23): Tip im

chy lin tc qua mch ct theo ng mu xanh v hng mi tn . Trng

thi cc rle v chc nng gim st thhin bng 1.3.


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Bng 1.3. Bng trng thi cc r le ca rle gim st mch ct

Rle ph C/khng in Tip imRle gim

Ghi ch

st

12 C 0

34 Khng 1

M

m

ch ct thng

ch (Tt)0

Khi mt in thao tc cp cho mch ct, chai r phu t tip

im le gim st ng cnh

Khi my ct ang trong qu trnh ct(Hnh 1.24): Khi rle bo vtc ng

(ng tip im trnh ct my ct

c th xy ra hin tng chuyn tip: Chai tip im 52a & 52b cng trng thi

nhb

le rv, ng

r stc bo.

Hnh 1.24. Phn bdng gim st khi my ct ang ct

-

u ra) sgi tn hiu n ct my ct, trong qu

iu din trn shnh 1.24. Khi ctip im u ra ca rle bo vv tip

im phca my ct u ng th khng c dng gim st chy qua rle gim st,

nu r le gim st l loi tc ng tc thi sa ra cnh bo (Sai). trnh

cnh bo nhm khi ct my ct th cc loi rle gim st ny thng hot ng c

thi gian trln hn thi gian ct my ct tng ng.

- Khi my ct trong trng thi m(Hnh 1.25): Dng gim st vn tn ti

nhng i qua c hai r le ph hai r le ph u c in r le gim st s

khng tc ng.


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37/131


Hnh 1.27. Logic ca chc nng gim st mch ct

- Sd

Bng 1.4. Bng trng thi

Bng trng thi cho thy, ch bnh thng ch c duy nht mt trng

hp s (3) l chai u vo u mc thp khi my ct ang trong qu trnh ct v

r le c th bo ng nhm. khc phc th r le 7UT6xx s lin tc kim tra

trng hi hai u vo ny (Cch nhau khong 500ms, c lm trln hn thi gianct my ct) v nu sau 3 ln kim tra lin tc pht hin li th r le mi pht tn

hiu nh bo.

hi c scxy ra (Mt ngun in thao tc, hmch ct, ...) chai u vo

u

thhin logic hot ng ca chc nng gim st mch ct trong r

le 7U

ng mt tn hiu u vo

Sny sdng khi rle chcn mt cng vo dnh cho chc nng gim

t mch ct. Tip im phmy ct c ni tt bi mt in trR c gi trln

nhmiu ttrong hnh 1.28.

t

c

K

trng thi thp (0V) duy tr rle scnh bo vskhng thng mch ct

ny.

Sny sdng chai tn hiu u vo(Trle bo v& my ct) nn

c u im l c thgim st mch ct kckhi my ct ang trng thi ct

hoc ng.Hnh 1.27

T6xx

s


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Nguyn l hot ng ca snhsau: Chbnh thng, mch gim st

lun c thng bng in trR hoc tip im phmy ct. Tuy nhin khi rle

o vtc ng, tip im u ra (TR) ang ng th khng c dng gim st chy

ua r le v chc nng ny c th tc ng nhm, trnh iu ny th qu trnh

kim tra mch ct din ra cch nhau khong 500ms hoc thm ch lu hn (30 giy),

nh cnh bo cha ra sau 3 ln kim tra lin tip khng thnh cng.

I.3. Gii thiu vI.3.1. Gii thiu chung vbo vmy pht in

y pht in ty thuc vovi chi ph cho h thng bo v.

Khn

Hnh 1.28. Sgim st mch ct sdng mt tn hiu

b

q

l

rle bo vmy pht in 7UM62x

Cc thng tin cn thit thit kmt hthng bo vcho my pht in c

thbao gm: Smt si ca nh my, vtr ca cc bin p o lng (U & I),

thng sca cc thit bny (Cng sut danh nh, cp chnh xc, hsgii hn,

khong cch ti tbng, thng sthit bng ct. Thm vo , phc vchc

nng bo vchng chm t cn cung cp thng tin vcc hthng cng u ni

vo thanh gp in p my pht (Nu c).

La chn sphng thc cthbo vcho mmc quan trng ca nh my & tng quan

g c tiu chun cthvsphng thc bo v, tuy nhin c cc khuyn

co vcc chc nng bo v ti thiu nn trang bnh trnh by trong bng 1.5,

nhn chung cc chc nng bo vc tng cng khi cng sut my pht in

tng ln.


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Bng 1.5. Cc chc nng bo vnn sdng (O: Ty chn, X: Nn dng, Y: Thy in tch nng)

Khi thit k h thng bo v, mt yu t quan trng cn tnh ti l tnh d

phng. Nguyn tc n-1 thng c sdng, ngha l hthng phi c thit k

sao cho shng hc ca mt phn tkhng gy dng shot ng ca ton bh

th g bo v. Vi cc nh my in, thng cu trc dphng c sdng phbin.

- Phng thc dphng mt phn: Cn sdng t nht hai hthng rle bo

v m bo hhng ca mt hthng khng lm mt ton bhthng bo v.

Cc bo vc thsdng chung cc bin p o lng, chung ngun nui v cc

m t c thchc mt cun ct (Hnh 1.29).

n

y c

Hnh 1.29. Dphng mt phn


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- Phng thc d phng y : Tt c cc phn t quan trng u c d

phng, v d: S dng cc bin p o lng ring bit, hai h thng bo v ton

ph , ngun nui r le ring bit, cc tn hiu ct cng i theo cc h thng khc

nha (Hnh 1.30). Chc nng ca hai h thng r le c thging nhau hoc thm

ch khc nhau vnguyn l bo v(V d: Mt rle c thda theo in p trung

tnh bo v90% cun dy stato khi xy ra chm t, r le cn li c thhot

ng da trn nguyn l bm dng tn sthp thc hin cng chc nng bo v

ny hoc tng tsdng nguyn l tng trthp v so lch dng in bo v

cho c

Khi hthng bo vhot ng, ty theo scm tn hiu ct sc gi n

cc my ct khc nhau (My ct u cc, my ct kch t, hthng van dng khn

cp, my ct pha cao p, my ct h thng t dng, ph ti a phng, cc h

th g hm dng, ...). Do tnh cht phc tp ca hthng ny nn thng sdng r

le ma trn ct nhn tn hiu v gi n cc my ct tng ng. Hnh 1.31 gii

thi rle thc hin tnh nng ma trn ct 7UW50 ca SIEMENS.

n

u

un dy stato).

Hnh 1.30. Dphng y

n

u

Hnh 1.31. Rle ma trn ct 7UW50


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42/131


- Bo vchng chm t 90% cun dy stato

- Bo vchng chm t nhy cao

n dy roto

t khng mong mun (Inadvertent

Energ

c chc nng

bo v .

I.3.3. nh c lp (I> hoc F50, F51)

phng cho i tng c

bo v n k.ca u cc, khi xy ra ngn mch

gn t

ng ca cc bo vqu dng thng thng. rle c

nh

p (U< hay F27). Chc nng

g Anh:

Volta

ca scngn mch) thrle

ng t, vi cc my pht ly in p kch ttu cc, khi xy

ra s in p cp cho hthng kch t

d ot

ng

7UM6xx c sdng hai gii php:

- Bo vchng chm t 100% cun dy stato

- Bo vchng chm chp gia cc vng dy

- Bo vchng chm t cu

- Bo v chng ng in my ph

izing Protection)

Trong cc phn tip theo s khng gii thiu ton bm ch c

tng i c trng v phc tp ca rle ny

Chc nng bo vqu dng vi c t

Chc nng bo vqu dng dng lm bo vd

hoc cc ng dy, my bin p cp di liVi cc my pht in ly in p kch t

h in p u cc st gim dng in ngn mch bgim i, thm ch gim

thp di ngng khi

y thng phi t gi trkhi ng thp xung v trnh rle tc ng khi

ti nng th sdng kt hp thm vi kha in p th

ny c gi l bo v qu dng kt hp vi kha in p thp (Tn tin

ge Controlled Overcurrent Protection). Nguyn l ca chc nng ny nhsau:

chkhi in p gim thp di ngng cho php (chboin p thp mi cho php phn tqu dng tc ng. Trong rle 7UM6xx,

chc nng kha in p thp c thsdng c lp hoc cng vi chc nng bo

vqu dng.

Gi trci t khuyn co i vi my pht:

- Dng khi ng ca phn tqu dng: cao hn 20 30 dng ti ln nht

- Kha in p thp: thng t di ngng in p lm vic thp nht cho

php (80% in p nh mc).

I.3.4. Chc nng bo vqu dng vi c tnh phthuc (51V)

Thng dng lm bo vchnh cho cc my pht nhv cp in p thp, lm

bo vdphng cho cc ma pht c cng sut ln.

Hon ton t

cgn th in p u cc suy gim gim

ng in ngn mch gim nhanh v bo v c th trv khng tip tc h

.

xl vn ny, rle


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- Bo v qu dng kt hp vi kha in p thp (51 & 27= Voltage-

Controlled Overcurrent): Khi in p gim di ngng cho php th rle in p

thp

ng ny stng iu chnh gi trkhi ng v c tnh tc ng ty theo

in khi ng ca

phn

Chc nng ny sbkha trnh cho rle hot ng nhm khi xy ra hin

t t p tmy bin in p (Do t cu ch, do maptomat nhthca VT).

Vi pht hin mt p c thda theo trng thi tip im phca VT hoc da

theo logic gm st in p bn trong r le (Tng t nh trnh by phn

I.2.10.5).Chc nng bo v ng dng tnh nng hm,

kha in p ty theo ci t.

I.3.5.

hiu quay ca roto, do qut qua roto vi tn sgp 2 ln tn slm

vict nng cun cn ca my pht. Chc nng ny ng

hot ng, cho php chc nng qu dng tc ng. Gi trkhi ng ca bo

vqu dng c tht thp hn so vi khi khng c kha in p thp

- Bo vqu dng kt hp vi hm in p (Voltage-Restraint Overcurrent):

Chc n

p h thng theo qui lut: khi in p gim xung th gi tr

tqu dng cng tng c gim i. Hnh 1.33 biu din quan hgia gi

trdng khi ng v in p (Trong hn vtng i), theo quan hny th gi

trkhi ng gim tuyn tnh khi in p nm trong ngng 25% 100% v khi

in p 25% th chcn bng 25% ca gi trci t ban u.

Hnh 1.33. Hsphthuc theo in

ng m

c

qu dng c th dng hoc kh

Chc nng bo v qu dng th t nghch (I2> hoc 46) - Unbalanced

Load

Chc nng pht hin ti khng cn bng da theo ln ca thnh phn dng

th t nghch o c. Dng th t nghch to ra mt t trng quay vi chiu

ngc li c

bnh thng gy ra cc dng xoy ti b mt roto pht nng cc b.Ngoi ra dng TTN cn gy ph


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thi cng pht hin c cc hin tng mt pha, ngc cc tnh CT hoc cc sc

khng i xng vi dng ngn mch nhhn ngng khi ng ca rle qu dng

pha t

Do cc tc hi ca dng TTN chyu th hin vic gy pht nng do

thng cc bo vqu dng TTN l loi hot ng c trda theo m hnh nhit

ca i tng c bo v. c tnh c sdng l loi c tnh thi gian ph

thu c, tuy nhin trnh trng hp khi xy ra ngn mch, dng TTN tng caonh o vvn hot ng c trth c tnh phthuc ca bo vc trang b

thm mt phn c trn hnh 1.34.

I.3.6. Chc nng bo v qu dng khi khi ng tmy (Startup Overcurrent

Prote

hng thng. Chc nng ny tng tnh trnh by trong mc I.2.6.5.

Hnh 1.34.c tnh thi gian tc ng ca bo vI2>

ng b

tnh c lp vi thi gian tc ng rt ngn nh

ction)

Hnh 1.35. Phm vi hot ng ca cc bo vkhi khi ng tmy (IST: Istartup prot.)


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Cc my pht tuabine kh c thc khi ng bng dng in tbbin

tn. Khi bt u qu trnh khi ng, bbin tn sbm dng vo my pht vi tn

st ng dn (Tng tphng php khi ng mm ng cin) to ra ttrng

qua vi tc tng dn. Ttrng ny sko roto v tuabine quay vi tc tng

dn tng ng, khi tc t khong 70% nh mc th tuabine c khi ng

(nh la, t kh sinh cng) v s t ko roto ti ng b, b bin tn c t

ng c

y

t ra. Trong qu trnh khi ng ny, my ct u cc trng thi m, tuy

nhin cng vn c khnng xy ra scngn mch trong lc khi ng. Do tc

quay tng dn dng in trong stato c tn scng tng dn, ngng tn s

thp (Di 10 11Hz) th cc bo vso lch v bo vqu dng ct nhanh khng

hot ng cn c mt bo vhot ng di tn thp (2 10Hz) bo vtrong

lc khi ng.Rle 7UM6xx c chc nng bo vqu dng hot ng di tn thp, mc

ch bo v trong qu trnh khi ng tmy. Do tn s thp nn xc nh

nhanh c gi trtc thi ln nht ca dng in cn sdng thut ton c bit

trong rle. Thhin phm vi hot ng ca cc bo vty theo tn sca my pht

trong qu trnh khi ng.

I.3.7. Chc nng bo vso lch cho my bin p (87T)

Hon ton tng tnh trnh by trong mc I.2.4; I.2.5 & I.2.6.4.

I.3.8. Chc nng bo vso lch my pht in (87)Nguyn tc thc hin bo vso lch dc cho my pht c thhin trn hnh

1.36, v phng thc bo vso lch ngang cho cc my pht c cun dy phn chia

thhin hnh 1.37.

Hnh 1.36. Bo vso lch dc my pht

Hnh 1.37. Bo vso lch ngang my pht


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Hnh 1.38.c tnh lm vic ca bo vso lch MF

c tnh tc ng ca chc nng so lch cho my pht in hon ton tng t

nhi vi bo vso lch cho my bin p (7UT6xx), tuy nhin cc gi trci t

l khc nhau. Gi trdng so lch ngng cao c xc nh theo in khng qu

ca my pht theo cng thc1

D F

d

I >> =IF 'dx' vi gi tr do

nht

I.3.9.

p kch tbgim thp, lin kt byu i v c thgy ra hin tng mt ng b

n Chc nn mt kch tc

7UM6xx c t in khng ri vo tnh trng lm

g gip

0 15 0 35d

x = ' , ,

3 7D FI >> = IF hhin trn hnh 1.38.

Chc nng bo vmt kch t(Underexcitation - Loss-of-Field) (40)Cng Lin kt gia roto my pht c quay bi tuabine v ttrng

quay ca stato phthuc vo ln ca ttrng to bi hthng kch t, khi in

gia roto v ttr g ca cun stato. g bo vkhi a rle

nhim vbo v cc my ph

vic mt ng bkhi xy ra hhng trong hthng kch tv mt khc cn

trnh c cc nh hng xu ti n nh ca hthng.

Lin quan ti chc nng bo vny, cn tm hiu vbiu gii hn cng

sut pht ca my pht (Generator Capability Curve): My pht c th lm vic

trong cc chpht (Qu kch t) hoc tiu thcng sut phn khng (Thiu kch

t), tuy nhin lng cng sut phn khng ny bgii hn bi mt syu tnh

sau:

- Cng sut tc dng pht ra: Bgii hn bi cng sut ca tuabine

- Cng sut phn khng bgii hn bi:

1. Dng in trong cun dy stato (Amature Current Heating Limit): khngc vt qu mc pht nng cho php


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2. Gii hn dng in trong cun kch t(Field Current Heating Limit): gii

hn bi pht nng trong cun dy roto

ing Limit):

gii ng sut phn khng ca my pht

ch

n trn hnh 1.39.

Cc gii hn trn y c xc nh da trn kt cu, cng sut ca my pht.

Tuy nhin khi my pht lm vic kt ni vi hthng th c thm cc gii hn khc

v nh tnh v n nh ng. Do cc gii hn vn nh ny nn c tnh cng

sut ca my pht thc tc dng nhtrong hnh 1.40. Nhvy, gii hn dng kch

tcho php nhnht t ht, da theo c tnh

ny c thci t cc gi trcho rle.

3. Gii hn pht nng li thp ti cnh ca stato(End Region Heat

hn ny nh hng n khnng nhn c

thiu kch t.

Cc gii hn ny c trnh by v biu di

Hnh 1.39. Biu gii hn cng sut MF

n

y theo c tnh cng sut ca my p


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Hnh 1.40. Gii hn cng sut ca MFc tnh ti n nh

Trong thc tc hai phng n thc hin bo vchng mt kch t:

1) Da theo tng tro c: Dng mt r le tng trt ti u cc my

pht vi vng bo vnhn vo pha trong my mt. chbnh th ng, my pht

spht cng sut phn khng tng ng vi gi trin khng o c X > 0,

khi hiu kich t c X < 0. Vy

sthay i gi trin khng o c sl mt tiu ch dng bo vchng mt

(Th p) kch t

biu

) Ring hng SIEMENS thc hin theo phng n khc: Dng gi tr tng

dn c thay v gi trtng tr. u im ca phng n dng gi trtng dn l

c th i trc tip tbiu cng sut pht ca my pht biu tng dn

my pht nhn cng sut phn khng v gi tro t

. thc hin c vic ny cn qui i biu cng sut pht sang

theo tng trgm hai thnh phn R & X v rle tng trchlm vic vihai gi trny. y l mt gii php c sdng rng ri.

Hnh 1.41. Qui i tbiu cng sut sang mt phng tng tr

2

o

qui


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(G & B) v trong hn vtng i cc gi trtng dn ny khng phthuc vo

in p ca my pht.

Cthvchc nng bo vtrong r le 7UM6xx: Cn cvo thcng

sut pht ca my pht, c tht ra 3 c tnh gii hn bo vnhtrn hnh 1.43.

Cc c tnh ny c xc nh bi vtr cc im gc v gc nghing tng ng.

Khi im lm vic ca my pht vt qu c tnh 1 & 2: Bo vskhi ng

v sau khong Thi gian trm bo hthng tng iu chnh kch tc thhot ng nng in p kch

tt

n

tc

Hnh 1.42. Qui i biu cng sut pht sang biu tng dn

thi gian tr(Khong 10 giy) sa tn hiu tc ng.

i mc cn thit. m bo bo vstc ng nhanh (Thi gian trrt ngn)

khi hng hthng iu chnh kch t, rle c chc nng gim st in p kch t

(Chc nng Uexcit.


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Khi im lm vic vt qu c tnh 3: Th bo vstc ng tc thi

t my pht do lc ny khng thm bo s lm n nh ca my pht vi h

ng.

.3.10. Chc nng bo v chng lung cng sut ngc (Reverse Power

rotection) (32R)

Khi ngun nng lng s cp sinh cng quay tuabin b mt th my pht

chuy

. Chng cgy nguy him cho tuabin, lm pht nng qu mc cnh

do cc hp s ny khng c thit k ch quay ngc.

Nguy

c rle in da vo dng cng sut ngc chy vo my pht, ln dng

cng sut ngc ny ty thuc vo ma st, tn hao do tuabin hot ng nhmy

nn v tn hao in trong my pht. Cng sut ngc ny phthuc vo thit kv

chng loi tuabin (Tuabin nc, hi, kh, diesel) v c thchchim mt vi phn

trm a cng su y in) hoc c

thln ti 100% vi mt sloi tuabin hi. pht hin c cc lung cng sut

ng

c

th

I

P

n sang hot ng chng c, nu h thng kch tvn hot ng th

my pht hot ng nhng ckhng ng bv ngc li nhng ckhng

ng b

tuabin hi do hi khng lu chuyn c lm mt, gy nguy him cho hp s

ca cc tuabin kh

n nhn gy ra chny c thdo li vn hnh, do trc trc my ct u cckhng ct khi ngng t my hoc do hng hc c kh. Trong cc nh my in

thng c chthng bo vckh v rle in pht hin hin tng ny.

Hnh 1.44. Chc nng bo vchng lung cng sut ngc

C

c t tc dng nh mc ca my pht (My pht th

c rt nhth php o ca rle phi chnh xc, rle 7UM6xx chsdng cc

i lng thtthun ca dng & p, mt khc sai sgc ca VT & CT cng gy

sai sca php o v do d cng c rle tnh n trong qu trnh tnh ton. Rlethng t c thi gian trtrnh hot ng sai do cc bin ng ngn hn. Mt


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khc trong chha ng bhoc dao ng in c thxy ra hin tng lung

cng sut ngc v do cn phi lm tr bo v trnh r le tc ng trong

trng hp ny. Tuy nhin khi van dng khn cp ca tuabin tc ng

(Emergency stop valve) th chc nng 32R nn c rt ngn thi gian tr, r le

thc hin logic ny bng cch nhn tn hiu tvan khn cp qua u vo nhphn

v kch hot rt ngn thi gian. Nguyn l hot ng ca chc nng 32R trong rle

7UM6xx thhin trn hnh 1.44

I.3.11. Chc nng bo vchng trt cc t(Out of Step) (78)

H thng in l h thng vn hnh trong thi gian thc, m bo cn bng

gia tng cng sut pht & tiu th. Khi trng thi ny c duy tr th tn ssgi

mc n nh, theo qui nh tn sc thcho php nm trong khong 500,2 Hz.

Bt cthay i no vngun pht hoc ti u dn ti thay i ca tn s, cc thayi ny xy ra lin tc trong hthng, tuy nhin do c cc h thng tng iu

ng hp xy ra cc

bin

in tng dao ng in c coi l n nh nu sau mt khong thi gianhth iu chnh vn hnh ti mt trng thi n nh xc lp mi. Hthng

chnh nn tn sc duy tr trong phm vi cho php. Trong tr

ng ln: Scgn nh my, mt cc ng truyn ti quan trng, ng ct

cc phti ln sgy ra smt cn bng t ngt gia cng sut in v cng sut

c ca tuabin (c coi l khng i). Smt cn bng cng sut trn trc roto

my pht lm cho tc roto sthay i, dao ng gc tng i gia roto cc

my pht ang hot ng cng sbdao ng, mt khc dng cng sut tc dng

phthuc chyu vo gc lch tng i ca roto cc my pht dng cng suttc dng cng bdao ng hin tng dao ng in.

Hnh 1.45. uo tn tro c

Hng t


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bcoi l mt n nh nu gc lch gia cc roto my pht tip tc tng ln (Trt so

vi nhau) v khng t c trng thi cn bng mi. Nhvy dao ng cng sut

l n trn bnh din hthng, cn trt cc tl hin tng dao ng mt n nh

khi nhn vo my pht.

nh (Trt cc ti vi my pht) th sphi c phn t

pht

i

Gii php bo v: Khi xy ra hin tng dao ng in, gi tr tng tr o

c ti u cc my pht c thri vo vng tc ng v r le s tc ng mt

cch cha cn thit. ngn chn hin tng ny phi c phn t pht hin dao

ng in v kha rle khng tc ng nhm - Chc nng ny l chc nng kha

khi c dao ng in (Power Swing Blocking - PSB). Tuy nhin khi dao ng in

pht trin thnh mt n

hin v tng thc hin cc thao tc cn thit tch my pht khi hthng

- Chc nng bo vny gi l bo vchng hin tng trt cc t(Out of Step -78). Chai chc nng bo vny u da trn vic o tng trv tc bin thin

ca tng tro c ( dZdt

), khi xy ra dao ng in th tng tro c sbin

thin chm (tc bin thin l hu hn) do roto cc my pht in c qun tnh

ln, khi xy ra scth tc bin thin ca tng trny gn nhl tc thi.

Hnh 1.46. Hthng n gin gm hai my pht

phn bit gia dao ng in n nh v mt n nh (Gy trt cc t) th

i xt ti quo bin thin ca tng tro c. Hnh 1.46 m tmt hthng

n gin gm hai my pht hot ng song song. Gi tr tng tro c v qu

o bin thin khi xy ra dao ng in c thhin trn hnh 1.45. Quo tng

trty thuc vo gc sin p ca haiu in p hai pha bng nhau th tng tr sdi chuyn theo ng thng

k=1).

rt cc t: im lm vic i vo c tnh mt pha v ci ra khi c

tnh pha i din.

ph

lch tng i ca roto hai my pht v tpha (N

Chc nng bo v chng trt cc t trong r le SIEMENS: cc r le ca

SIEMENS hon ton da trn nguyn l gim st quo tng trpht hin hin

tng dao ng in hoc trt cc t. mt tc tnh tc ng tiu chun ca rle

h7UM6xx.

- Quo chuyn ng theo ng 1 hoc 2 xy ra khi c hin tng mt n

nh, t


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- Quo 3 & 4: Din bin khi c hin tng dao ng in n nh.

Da theo c tnh ny th logic pht hin trt cc ttrong rle 7UM6xx nh

sau:

- Dao ng in l hin tng 3 pha i xng: Thnh phn dng in TTN

phi

ong mt

kho

hng thhi phc, dn ti trt cc tphi ct my pht.

I.3.12

Cc my pht in thng c trung tnh cch in hoc ni t qua tng tr

hn chdng chm t. Hin tng chm t cun dy stato c th l tcun

dy thng qua chcch in bha than ti li thp hoc thng qua hquang ti li

thp. Cc th nghim cho thy rng khi chm t c pht si quang th ch

cn vi dng in 5A c th gy ph hy cch in ca cc l thp stato, t

gy ra cc sctip o nhng gi trdng

in chm t c thgy nguy him thng c gii hn trong khong 5 15A.

nhhn ngng cho php.

- C ghi nhn sct c tnh chai pha (i vo v i ra pha i din) ca

vecto tng tr.

- Khi s ln ct c tnh c ghi nhn t ti ngng ci t tr

ng thi gian cho php th rle stc ng v nhn nh y l xy ra dao ng

in k

. Bo vchng chm t 90% cun dy stato (59N, 64G, 67G)

Hnh 1.47.c tnh a gic chng trt cc t

nh h

theo. Khng c mt tiu chun cthn


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Nguyn l bo v chng chm t 90% cun dy stato s dng trong r le

7UM6xx da trn nguyn l:

- Da theo in p trung tnh: khi xy ra chm t, vecto in p 3 pha bmt

cn bng in p im trung tnh s tng ln. in p trung tnh c th nhn

c thng qua:

- My bin in p ni ti trung tnh cun dy vi t hoc tmy bin p

trung tnh (Nu sdng my bin p ni t trung tnh).

Sdng my bin in p c cun tam gic hhoc ly tmy bin p to

trung tnh.

- Da theo ln dng chm t: nu my pht u theo sni b, c ph

ti a phng th dng chm t c thln (Dng in dung) v ln dng chm

t ny cng l mt yu t xc nh hin tng chm t. Do dng chm tthng c gi trnhnn gii php s dng BI th tkhng (BI0) thng c u

i hn, tuy nhin s ng vn c th s

dng.

Hnh 1.48. Bin php o in p im trung tnh

-

m u BI trung tnh hoc dng 3BI c

Hnh 1.49. Bin php ng chm to d


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- Trong mt strng hp, phn bit gia sctrong hay ngoi my pht

cn sdng thm bphn nh hng cng sut thtkhng.

Vy, chc nng bo vchng chm t 90% cun dy stato skhi ng khi:

- in p im trung tnh vt qu ngng ci t

- Dng in chm t o c vt qu ngng ci t v hng vo trong

my pht (nh hng).

pha.

hot

I.3.13. Bo vchng chm t 100% cun dy stato

I.3.13.1. Sdng sng hi bc 3 (27/59TN 3rd Harm.)

hc nng ny sdng c tnh l tt ccc my pht in u sinh ra khng

nhng thnh phn in p tn scbn m cthnh phn in p tn scao (Hi

in p). Trong cc thnh phn sng hi th thnh phn hi in p bc 3 chim

chyu khnga thnh phn in p ny lc

Phng php ny chbo vc 9095% cun dy stato tnh tu cc do:

- Gi trkhi ng ca rle in p im trung tnh phi ln hn gi trc th

xut hin trong lc vn hnh (Do ti khng i xng) thng t 510% in p

- in p im trung tnh sgim dn khi im chm t xut hin gn trung

tnh hn: Khi im chm t cch trung tnh 5 10% svng dy th in p imtrung tnh c th thp hn ngng khi ng chc nng bo v ny s khng

ng khng bo vc 100% cun dy stato. Tuy nhin vi 5% cn li

ca cun dy stato th xc sut xy ra schng cch in l rt nhdo in p

thp, v vy vi cc my pht nhc thchsdng chc nng ny l , vi cc

my pht cng sut ln th cn phi c thm bo v100% cun dy stato.

Hnh 1.50.in p im trung tnh & dng in chm t theo vtr im sc

C

, thnh phn sng hi bc 3 c tnh cht tng tthnh phn thtv phn bty theo sthay thTTK. Sphn bc


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bnh thng v khi c scchm t ti trung tnh & u cc thhin trn hnh

1.51.

Da trn sphn bca hi in p bc 3 c ththy rng khi scchm t

gn trung tnh (Cc bo vtrc khng pht hin c) th:

- Gi trhi in p bc 3 o c ti u cc sl ln nht sdng s

vi rle in p cao u ti u cc (Hnh 1.52).

Hnh 1.51. Phn bthnh phn hi in p bc 3

Hnh 1.52. Svi rle in p cao 59T


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- Hoc chbnh thng gi trhi in p bc 3 ti trung tnh c gi tr

nht nh no , khi xy ra scgn trung tnh in p ny gim xung xp x

0 dng svi rle in p thp ti trung tnh

Sny lun sdng cng vi sbo v90% cun dy stato, hai bo v

ny phi c vng chng ln m bo lun bo v c 100% cun dy stato

(B vda trn hi in p bc 3 c mt vng cht ln cn im phn bin p

bng 0 c

ng

I.3.13.2. Sdng ngun phtn sthp

s

o

a hi bc 3 - hnh 1.51).

Do ln ca thnh phn hi in p bc 3 ny phthuc vo ti nn trong r

le 7UM6xx c chc nng tng thay i gi trchnh nh ca rle theo ln

d cng sut tng nhy cho bo v.

Hnh 1.53. Svi rle in p thp 27H

Hnh 1.54. Nguyn l bo vdng ngun ph


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Cc phng thc bo v chng chm t cun dy stato trn u ph thuc

vo c tnh ca my pht v phng thc kt ni, s lng ph ti, ... nu im

ch t gn trung tnh khng c pht hin th my pht hot ng chgn

tng t trung tnh ni t trc tip. Scchm t thhai nu xy ra ssinh ra

dng

chm

t th

bi cc hi bc cao c trong my pht

v h

m

scrt ln (Do my pht in c tng trTTK nh), c thln hn cdng

sc3 pha. V l do , cc my pht loi ln thng c trang bvi chc nng

bo vchng chm t cun stato da trn vic bm ngun phtn sthp.

Nguyn l hot ng: Pht mt in p tn s thp vo trung tnh ca my

pht, in p ny s sinh ra mt dng in tn s thp, ln dng in ny ty

thuc vo tng trngun pht, in dung ca cun stato so vi t. Mt rle qu

dng c sdng gim st dng in tn sthp ny. Khi xy ra sc

in dung cun stato bni tt v dng in tng ln, bo vskhi ng.Hnh 1.54 m tnguyn l hot ng ca chc nng ny.

Ngun phsdng vi tn sthp :

- Ti tn sthp th tng tr(Dung khng) ca cun dy stato c gi trln

dng in tn sthp chbnh thng snhgi trkhi ng c tht

thp hn tng nhy ca bo v.

- Tn hiu tn sthp skhng bnhiu

thng ddng lc c tn hiu mong mun.

Hnh 1.55. Cch u ni ngun ph20Hz


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ng dng trong rle 7UM6xx: Rle ca SIEMENS sdng ngun phtn

s20Hz vi in p khong 25V. in p ny c tha vo trong my pht theo 2

cch (Hnh 1.55):

in p (20Hz) bm vo VSEF v dng in (20Hz) thu c

iSEF n thhin trn hnh 1.56.

Tcc tn hiu dng & p ny r le s tnh ton ra gi trin trchm t

E), khi gi ng (C hai

trng thi: Bo ng & tc ng) nhthhin trn hnh 1.57. Ngoi ra dphng

cho c

- Thng qua my bin p to trung tnh gi

- Thng qua bin p ni t trung tnh cun stato

Cc tn hiu

a vo trong rle. Sthay thtnh to

Hnh 1.56. Sthay thtng ng tnh ton in trchm t

(R tr tnh ton c nhhn gi trci t th rle skhi

hc nng bo vbng ngun phth rle c sdng thm chc nng bo v

qu dng chm t vi dng in o c trong mch (Bao gm cdng in tns 50Hz v 20Hz), chc nng ny lm nhim v d phng v bo v khong

8090% cun dy. R le cng c chc nng gim st s thng mch ca mch

20Hz.

Hnh 1.57. Cc gi trci t cho chc nng chng chm t 100% cun stato


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Hnh 1.59. Bo v chn s c ia cc vn d

- Phng thc hi xy ra scgiacc vng dy th vecto in p ba pha mt i xng v bin in p vi cun tam

gic

c ni t qua my bin p.

Khi xy ra scchm t th in p o c tVT pha trung tnh v phau cc l nh ng.

tiu chun: Nhtrnh by trn hnh 1.59. K

hu ni ti u cc my pht so c lch in p r le s tc

ng. Tuy nhin khi xy ra scchm t th cun tam gic hny vn o c

in p v r le c th tc ng nhm, trnh trng hp ny th trung tnh ca

cun scp ca VT bt buc phi c ni ti trung tnh cun dy stato ca my

pht in. Do trung tnh cun stato c th c in p ln ti in p pha nn bt

buc phi sdng cp cao p. Phng thc bo vny c nhy cao, gi trci

t chphthuc vo in p sinh ra do skhng hon ton i xng trong vic btr cun dy trn stato.

- Phng thc u ni khc (Hnh 1.60): Phng thc ny c thsdng khi

trung tnh ca my pht

Hnh 1.60. Phn thc bo v khc chn s c ia cc vn d

nhau, do in p t vo rle sbng 0 v rle khng tc


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Hnh 1.62. Phng php bm ngun phxoay chiu

- Phng php

in p xoay chiu c bm vo mch roto cng vi mt rle qu dng uni ti khi c scchm t

v c

nh phn

ny c

m t xy ra th cc in dung ca cun dy roto bni tc

thng

o chni t ca cun dy roto. Thng thng dng in chy xung t

si

bm ngun phxoay chiu (Hnh 1.62)

p (Rle 64F). TC c tc dng hn chdng qua rle

ch ly gia mch roto in p mt chiu v mch bm ngun p xoay chiu.

chbnh th

Unlocktai Lieu Chuyen de HCác điều kiện hòa đồng bộ MFĐ vào lưới1. Cùng tần số...

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Transcript of Unlocktai Lieu Chuyen de HCác điều kiện hòa đồng bộ MFĐ vào lưới1. Cùng tần số...