dlca va ktkph upadated 10_2013-2

B mn H thng in

Vin in

l o lng cao pvv

Th nghim khng ph hyg g p y

department of power systems H A N O I U N I V E R S I T Y O F S C I E N C E A N D T E C H N O L O G Y

Phm Hng Thnh, Bi ging dnh cho hc vin cao hc

Ni dung

H thng pht in p cao v dng in ln

Cc thit b o lng in p cao v dng g p gin ln

Cc phng php th nghim gim st Cc phng php th nghim, gim st v chn on cch in


o lng cao p & Th nghim khng ph hy

1. H thng pht in p cao & Dng in ln

1.1. PHT IN P MT CHIU



1.1.1. in p mt chiu

ng dng: My photocopy, ng phng, lc bi, tuyn qung, my gia tc ht, my X-quang

Th nghim TB: Cp (khng cn dng in dung)

nh ngha v in p mt chiu:

IEEE 4-1978:IEEE 4 1978: nhp nh (ripple):

H s nhp nh (ripple factor): V/Vd 5% cho th nghim, p ( pp ) d ghoc tnh hung c th (tiu chun, loi thit b, loi th nghim)


Phn I: H thng pht in p cao v dng in ln

1.1.2. Mch chnh lu na chu k (1)

a. S nguyn l

b. in p chnh lu khng c t

c. in p chnh lu c t C

RL : ti

Dng qua ti trong mt chu k:

in p trn C thay i dV trong dt in tch x bi C: Q=C(Vmax-Vmin)=2VC

Nh vy:



Mch chnh lu na chu k (2)

gim nhp nh cho in p chnh lu: Chn t l (smoothing capacitor) tr s ln ( g p ) Tng f, tr s thng thng trong phng th nghim ln n 10kHz

Nu s dng b lc nhiu tng hoc b in t: V10-5

Nhc im ca mch chnh lu na chu k:K h th l U l t Kch thc ln nu cn Uoutput ln v trn

Mch t MBA b bo ha nu IL Im ca MBA Khng s dng c cho truyn ti HVDC: do I nh Khng s dng c cho truyn ti HVDC: do Ioutput nh



Mch bi p- Greinacher voltage double

N h k C h h h h k d Na chu k m C1 c np nh hnh v, na chu k dng cc tri C1 c in p Vmax cc bn phi C1 l 2Vmax V2 dn np cho C2 n 2Vmax Thng thng Voutput

Mch bi p ni tng-Cascade voltage multiplier (1)

Ch khng ti: in p trn t ct tri dao ng vi in p ngun (ct dao ng), ct phi gi nguyn (ct l-smoothing column), Voutput =2nVmax Ch c ti: nhp nh v in p ri



Ch c ti: nhp nh v in p ri.

Mch bi p ni tng (2)

nhp nh ph thuc ch yu vo Cn:

n gin chn C cc tng ging nhau in p ri trn ti ph thuc vo s tng: V d V =100kV f=50Hz C=7F I=500mA n=10 tng



V d Vmax 100kV, f 50Hz, C 7F, I 500mA n 10 tng

My pht tnh inN l N l t ti th h Nguyn l: Nng lng c trc tip thnh nng

lng in, in tch di chuyn ngc vi in trng tch ly th nng cao

ai cch in rng b, vn tc v, mt in tch , khong cch in cc d in tch trn mt n v di dq=bdx

Cng sut c Pc = Fv=Pin= UI

My pht van de Graaff: b t vi cm n vi m, v=1530m/s, HT phun in tch: in cc kim ni vi ngun DC thay i: 10100kV to p gia kim v ai. Bao bng c tt (e.g:SF6). in tch di chuyn ln trn v c thu liin tch di chuyn ln trn v c thu li bng cc nh ni vi HV terminal.



My pht tnh in van de Graaff(2)

Dng in np I=dq/dt=bv, my ti Oak Ridge National Laboratory: U=25MV u im: in p cao t mo d iu chnh u im: in p cao, t mo, d iu chnh

Nhc im: dng nh (ph thuc v) di mA, d b rung v ln

ng dng: gia tc ht, nghin cu tia X, sn tnh in, th cp cao p



H thng pht in p cao & Dng in ln

1.2. PHT IN P XOAY CHIU



1.2.1. in p cao p xoay chiu

Hu ht thit b in s dng in p xoay chiu

Cc thit b cn c th nghim U~ , 1 pha d vn hnh in p 3 pha

Ngun in p th nghim: My bin p (MBA) th nghim

MBA th nghim dng U cao, I nh P nh: k 1: h s nh hng ca in dung ph k 1: h s nh hng ca in dung ph Ct : in dung ca mu

I=Pn /Un =10mA1A, e.g: my ct, s xuyn: 0,1 0,5A; MBA lc: 0,5 1 A



in p th nghim xoay chiu

in p th nghim Vt thng l in p ln nht pha-pha Vm trong hthng in thi gian th nghim: 1 phtthng in, thi gian th nghim: 1 pht

Vt cho cc thit b khc nhau l khc nhau v ph thuc vo kiu phihp cch in trong h thng. i vi Vm< 300kV, t l Vt/Vm n 1,9 vc th gim vi in p Vc th gim vi in p Vm.

i vi cc thit b c cun dy v li thp, tn s ca in p thnghim phi c nng trnh hin tng t ha li thp.

Dng in p phi l dng sin chun, gi tr hiu dng ca sng hikhng c vt qu 5% tr s hiu dng ca sng c bn



MBA th nghim vs MBA lc

MBA th nghim c cng sut nh

MBA th nghim c d tr cch in (insulation margin) nh hnMBA l d kh h QA t h tMBA lc do khng chu QA st hoc ng ct

MBA th nghim lm vic ngn hn (

My bin p th nghim n tngKi (kh d ) h n tng c im gia cun cao ni t cun Kiu c (khng dng s xuyn) nh

hn kiu b, nhng tn nhit km hnn tng c im gia cun cao ni t, cun

h 2 qun xung quanh cun 3a, 4a&b: cun b gim in khng r gia 3b v 2. in p u ra ln hn n tng thng thng

1- Li thp, 2- cun h, 3- cun cao, 4- vng san in trng (field grading shield), 5- v ni t v , 6- s

7 h i 8 i 1- Li thp, 2- cun h, 3 a v b- cun cao, 4a&b cun b 5 cun kch thch



xuyn, 7- v cch in, 8- in cc cao p 4a&b- cun b, 5- cun kch thch

MBA th nghim ni tng (cascaded)S d h U 400kV S dng cho Uoutput 400kV

Mi tng 3 cun (tr tng cui), cun thcp T1 ni tip vi cun th cp T2, cunk h th h ( 3) i i kch thch (cun 3) ni vi cun s cp caT2

Tng cui (ch) dng hai cun dy

u im: cc tng c th s dng ringbit, nh v d vn chuyn

Nhc im: Cun s cp ca tng u p gtin mang ton b ti,tng tr trong khngphi cng i s cc tng, vd: mi tng cin khng ngn mch 2,5% th 2 tng: 8%, ba tng:23% Khi chu qu in p in pba tng:23%. Khi chu qu in p, in pt ln cc tng khc nhau l khc nhau

Vit Nam, phng th nghim trng im: Ngun xoay chiu 3400 kV= 1 2 MV



Ngun xoay chiu 3400 kV= 1,2 MV

Hin tng in p tng khi th vi ti in dung

yes dung

Th nghim cch in ca thit b ti l in dung Qu in p c th sinh ra do cng hng gia in cm ca MBA th nghim vin dung ca thit b, hoc qu in p phc hi xut hin trn thit b sau khi xy rasau khi ct dng ngn mch do phng in trn thit b

MBA th nghim thng c bo v qu in p bng khe h cu phng in vthit b ngt in t

MBA th nghim c bo v bng in tr cao p: hn ch dng in khi phngin l (damp) in p cng hng v in p phc hi



in, l (damp) in p cng hng v in p phc hi

MBA cng hng (resonance transformer)

L: bin in khng, 0:li thp, 1&2: Cun cao v h, C: vt th nghim

in p t ln mu C:

L c iu chnh xy ra cng hng: XL =XC UC/U =L/R=Q, h s cht lng (quality factor)

Q h 40 100 i h 10kV h 00kV I Q c th t 40100 in p u vo nh 10kV c th to ra 500kV u ra, I c th n 30A

u: in p sin hon ton (hi khng b khuych i) in p phng in chnh t 1/Q t ti (P ) d h h (khi b kdxc; cng sut ngun =1/Q cng sut ti (PC); dng ngn mch nh (khi breakdown

th mt cng hng), nh gn

Nhc: cn thm L chu Umax,Imax; in p u ra ph thuc vo k cng hng; h d h ti C t l khi PD ti



ch s dng cho ti C; st p ln khi c PD ti

MBA cng hng (2) Cc mun in khng (12 n v) ca mtca mt MBA cng hng c f thay i

i vi trm GIS, my in quay ln hoc cp ngoi thc a: yu cu thit b th nghim nh, C thay i trong di rng

MBA cng hng s dng L khng i (nh), f iu chnh t cng hng:

Q t 50150; f=501000Hz, nh gn v d chuyn ch MBA ni tng: 1020kg/kVA; MBA cng hng: 36kg/kVA; cng hng bintn: 0 5kg/kVA



tn: 0,5kg/kVA


1 3 MY PHT IN P XUNG1.3. MY PHT IN P XUNG



nh ngha xung in p

in p xung: st v ng ct

Theo IEC, xung st tiu chun: T1=1,2s30%; T2=50s20%; xung ng ct: T1=250s20%; T2=2500s60%



My pht xung n tng

in p t ln ti (1, 2 tnh t R1,R2,C1,C2):

H s hiu qu in p =Vp/V0 100%

Thi gian nh tmax :

Nhc im: khi pht xung ln phi Nhc im: khi pht xung ln phitng kch thc ca khe h, C, R vvng quang pht sinh. Ch dng cho U n 200kV



My pht xung a tng Marx

Rc in tr np cho C, Rf kim sot thi gian u sng, Rq kimqsot thi gian ui sng, Rc>>Rq>>Rf Ban u tt c cc bn cc A c np n in th U0, B c inth t (0). Hiu in th trn C l U0. Thi gian t vi s n 1/

Khe E1 phng trc (nh hn cc khe cn li) A2, A3 cnp n 2U0, 3U0 C c ni tip vi nhau C v C2 cnp Rf ni tip, sau c phng qua Rq v Rf in p ln n hng chc MV (mi tng vi trm kV), HVLab(Vin nng lng): 3,6MV; 18 tng; 180kJ

Nng lng:



Nng lng:

My pht xung dng

ng dng: Kim tra kh nng lm vic ca in tr phi tuyn, h quangin, plasma

Dng sng cho th nghim R phi tuyn (IEC): 4/10s v 8/20s Cu to: Nhiu C np song song vi nhau, sau phng qua R-L ni tip

Khi G phng in p V, dng qua ti im:

Vi nng lng cho trc, L cng nh th Im cng ln



Phn II:Phn II:

Cc thit b o lng cao pCc thit b o lng cao p



Thit b o in p cao & Dng in ln

o in p cao o dng in ln


Phn II: Thit b o in p cao v dng in ln

Khe h phng in- Khe h cu

ng dng: phng php tiu chun o Upeak (AC, DC, xung), kim tra ccng dng: phng php tiu chun o Upeak (AC, DC, xung), kim tra ccthit b o lng cao p

Yu cu: tf >1s, tt > 5s (xung), khong cch

Vn mt tnh in Nguyn tc: Da trn hiu ng lc tnh in Coulomb (o Uhi d ):Nguyn tc: Da trn hiu ng lc tnh in Coulomb (o Uhiu dng):

in p xoay chiu: S: khong cch A: din tch

Cu to: mt c nh, mt di chuyn (50V n 1000kV, di tr s ny lc ht qu nh nn khng chnh xc

i t t t u im: tng tr u vo rt cao (Rinput>1012 , C~10pF) nn khng tiu th cng sut ngun

D AC DC


Dng o AC v DC


1 O IN P MT CHIU1. O IN P MT CHIU



in tr cao+in ki t i i A k R i t in tr cao ni vi mA k: R c vi trm

M, in p ri trn in k khng ng k (R in k ch vi ) U=IR. Thit b bo v in k chng qu pThit b bo v in k chng qu p (phng in hoc R hng): diode Zener hoc khe h giy

in tr qun t cc in tr con ni tip t h h i b t trnh phng in b mt v vng quang

Hn ch: Tn tht cng sut do dng i qua in tr, c tnh ph thuc ca R vo nhit , c tnh R ph thuc vo in p

c ch to o in p n 500kV


Phn II: Cc thit b o lng cao p

Vn mt quay (generating volmeter) Thng thng o in p mt chiu bng cch niThng thng o in p mt chiu bng cch nitip vn k vi mt R cao hn ch dng qua vn k1000kV.

i DC d h i in p DC cao, dng phn p in tr + vn mttnh in, nhng vn c vn v dng r.

S dng vn mt quay loi b c nhc im do dng r, dng o in p cao trong trng hpdng r, dng o in p cao trong trng hpkhng cn ni vo in cc cao p

Nguyn tc: dng in qua in dung l o hm cain tch theo thi gian

in p mt chiu ta c: Nu in dung thay i theo hm sin:

Tr s hiu dng:Tr s hiu dng:

Nh vy dng in chy qua in dung t l thun vi in p t vo in dung.


Vn mt quay (2) Mt vn k quay c cu to t mt hnh tr in cc cao p D3 in cc cMt vn k quay c cu to t mt hnh tr, in cc cao p D3, in cc cnh D1 v D2, in cc quay D0 c quay bi ng c ng b.

Hnh dng v s cnh ca D0 v D1 to ra in dung gia D2 v D3 thay idng sin

Dng in c chnh lu v o bi mpe k cun dy di ng (moving coil), cth c khuych i nu cn thit.

u im: Khng ni trc tip vi thit b cao p, khng tiu th dng ti, thang o tuyn tnh. C th s dng o AC nu vn tc quay ca ng c =1/2 vn tc bin thin ca tn hiu cn o, e.g: ng c 4 cc o 50Hz cn c vn tc 1500 rpm

Nhc im: Phi chnh nh b phn quay sn xut phc tp do c b phnquay, sn xut phc tp do c b phn quay


Cc thit b o lng cao p

2. O IN P XOAY CHIU &

IN P XUNG



in k ni tip in dung T dng in qua in k tnh c in p cn o; I=jCUT dng in qua in k tnh c in p cn o; I jCU Nu c cc sng hi, tr s tng tr ng vi C s thay i, in p hiu dng o c s l tng ca cc in p thnh phn:

D i i t th h h hi Dng in ng vi tng thnh phn hi:

Dng in hiu dng c tnh theo cng thc:

Nh vy vi 10% sng hi bc 5 th dng o c ln hn dng tn s cn o l 11,2%, tng ng vi sai s 11,2% in p cn o. V vy khng s dng phng php ny nu in p cha cc thnh phn sng hi Thit b loi ny s dng o in p n 100kV mpe k c di o t 0 n 100AThit b loi ny s dng o in p n 100kV, mpe k c di o t 0 n 100A


Mch Chubb-Fortescue Dng o in p nh l do: i khi cn bit tr s in p nh hn l tr sDng o in p nh, l do: i khi cn bit tr s in p nh hn l tr s hiu dng (tr s bn in)

Nguyn tc: Khi 1 in dung c ni vi ngun xoay chiu, dng in np ca in dung c tnh bi:

Dng in trung bnh:

T dng in o c, in dung v tn s xc nh c in p nh Mi diode chnh lu mt na chu k (back to back) Phng php ny khng(back-to-back). Phng php ny khng s dng c nu in p nh hai na chu k khng i xng, hoc c nhiu hn mt nh mi na chu knhiu hn mt nh mi na chu k.


Phn p in tr-nhnh cao p Nguyn tc ging nh o in p mt chiu: in tr nhnh cao p bao gm mtNguyn tc ging nh o in p mt chiu: in tr nhnh cao p bao gm mt nhm cc in tr c lp, in tr thng s dng l loi mng kim loi hoc carbon c t cm thp v in dung k sinh nh. in tr c dng phi l loi t ph thuc vo nhit v in p

T b khi i h h d h h h h Ton b khi in tr cao p thng t trong thng du hnh tr trnh phng in vng quang

Mi MV ca phn p in tr c di khong 4m, v th ch dng cho in p di 1MV, in dung k sinh nh hng ng k ln kt qu o nu di lndi 1MV, in dung k sinh nh hng ng k ln kt qu o nu di ln

Khi c in dung k sinh, hm truyn c dng:

Tr s C2 c th thay i bng cch iu chnh in dung ni song song sao cho g g gR1C1=R2C2, khi t s phn p khng ph thuc vo tn s:


Phn p in tr-nhnh h p m bo an ton dng c hin th (oscilloscope) c t cch phn p mt m bo an ton, dng c hin th (oscilloscope) c t cch phn p mt khong cch nht nh. i vi o AC v DC th khng c vn g, tuy nhin i vi in p xung th tng tr sng Z ca cp ni nh hng quan trng n tn hiu o

Cp ng trc thng c Z t 5070, phi phi hp tr khng (match) bng mt i R Z kh hin tr R=Z khng c sng phn x

R==Z


Phn p in dung (1) loi b sai s do sng hi ngi ta thng s dng phn p in dung loi b sai s do sng hi, ngi ta thng s dng phn p in dung

Phn p in dung l tng dng o in p c dc ln hoc xung, t s phn p khng ph thuc vo tn s nu in tr r nh

T s phn p: Mn chnT s phn p:

C2 bao gm in dung ca phn p v C2 bao g du g ca p p ph kin (cp ni, in dung u vo oscilloscope, in dung k sinh ..). C1thng bao gm nhiu in dung thnh phn ni tip nhauphn ni tip nhau Cc in dung c ch to vi t cm nh, khng c PD, thng l t khng kh hoc kh nn. T l phn p c th l 1000:1 vi in p n 350kV v c gii hn tn s n 100MHz


Phn p in dung (2) in dung lun tn ti cc in cm k sinh L c vi H cng vi in dung kin dung lun tn ti cc in cm k sinh Ls c vi H, cng vi in dung k sinh vi t to thnh ng dy di dn ti hin tng truyn sng to ra dao ng: mt xung i vo ng dy ny to ra hin tng dao ng c suy gim t.

loi b dao ng ny, ngi ta ni tip vo C cc in tr hp th R

Nhnh h p c ni vo oscilloscope qua mt in tr u vo tr s Z-R v cp ni tng tr sng Z. Khi in p xung ini tng tr sng Z. Khi in p xung i vo nhnh h p, n s c chia ra trn in tr u vo v tng tr sng. Tn hiu xung i vo cp v tng gp i v tr h mch ca oscilloscope. Sng phn x b c ca osc oscope S g p bhp th bi in tr u vo Z-R ni tip vi in tr hp th R, do vy tng tr tng cng ca h ni tip ny chnh bng Z


My bin in p in dung (CVT) M rng ca phn p in dung bng cch sM rng ca phn p in dung bng cch s dng thm mt tr khng L v mt my bin p (Capacitance voltage transformer)

Thng c dng cp tn hiu cho cc r le boThng c dng cp tn hiu cho cc r le bo v trong ng dy cao p hoc dng km vi vn mt tnh inC2 ly in p trung, t 1030kV gim gi

thnh nu s dng trc tip my bin p ni trc tip vo ng dy, my bin p h t in p ny xung t 100500V o lng L1 phi hp vi in cm tng ng ca myL1 phi hp vi in cm tng ng ca my bin p loi b in dung phn p tn s cng nghip lm cho my bin p h p cn thun tr khng c lch pha gia in p s cp v th cp MBAca MBA



3. O DNG IN LN



3. o dng in (xung) ln Nguyn nhn: ngn mch ng ct dng stNguyn nhn: ngn mch, ng ct, dng st

Mc ch: Xc nh nhit pht nng, cc gii hn v nhit cho thit b (my ct, dy dn) i vi dng ngn mch; i vi dng st: xc nh mc nguy him ca dng st ( ln, dc, thi gian tn ti)ca dng st ( ln, dc, thi gian tn ti)

Cc c trng ca dng in xung: i vi xung st (4/10s-n 100kA hoc 8/20s-n 40kA). Xung dng in vung ng vi x (discharge) ca ng dy di vi Td ng vi khong thi gian I=0,9Imax i vi chng st (surge diverter) ni d g g g , max. g ( g )chung, ngi ta thng th nghim vi Td 2000s (n 4kA). Xung do ngn mch ca dng 50Hz c th nghim vi dng xp chng dng sin vi thnh phn DC


Dng hiu ng cm ng- Cun Rogowski Nguyn tc: Khi hai mch gn nhau, hin tng h cm gia hai mch lm choin p u ra ca li: U2(t)=-i2R2-L2di2/dt+Mdi1/dtNu h thng o c tng tr trong v cng lnth i =0 v:th i2 =0, v:U2(t)=Mdi1/dt vi M=n0rA/L, n: s vng dy;A: din tch mt vng dy, L: chiu di cun Rogowski

Rogowski l loi li khng kh (air coil) khc vi my Rogowski l loi li khng kh (air-coil), khc vi my

bin dng dng li st (iron-coil) khng c hintng bo ha t. Cc dy c qun trn khung

bng vt liu non-magnetic

in p U2 t l vi vi phn ca dng cn o theo thi

gian, v th tnh c dng cn o phi qua khug g p q

tch phn

Dng o dng in xung, bin i nhanh v tr s ln,

di tn n 100MHz


di tn n 100MHz

4. o dng mt chiu dng in tr shunt tr s thp

ng dng: o dng DC hoc AC c tn s thpng dng: o dng DC hoc AC c tn s thp

in tr thay i t 1 n 100m, tr s in tr thp lm cho in dung k sinh v t cm nh lm cho cc tr s ny (L,C) c th b qua cho tn s n 100Hz lm cho in p o ch vi Vin p o ch vi V

Khi tn s cao, in p o c bao gm:

U=iR+Ldi/dt+d/dtNu t trng k sinh c th loi b bng

cch screening th t cm L gy sai s ln

Thng s dng in tr lm t mng carbon ni song song hoc dy in tr Thng s dng in tr lm t mng carbon ni song song hoc dy in tr (wire resistor) c t cm thp.


4. o dng 1 chiu dng cm bin Hall ng dng: o dng in mt chiu

Nguyn tc: Khi dng in chy trong tm kim loi t trong t trng, cc in tch (e) sb lc Lorentz ko theo hng vung gc vi t trng v dng in (quy tc bn tay phi)

in p Hall:

Khi dng mt chiu tr s ln, dy dn xuyn qua mch t v t trng to ra gy hiung Hall trn phn t Hall (Hall element)


5. Cm bin in quang (electro-optic sensors) u im: o trc tip in trng trong khng gian; khng c mch in t v khng cngun cp; p ng vi in trng t DC n GHz; phn b in trng ch b mo bicm bin nn c chnh xc cao hn, nh gn d di chuyn

ng dng: dng nhiu trong cc b chuyn i tch hp in quang v in t gim stcch in trong my bin p my ct GIScch in trong my bin p, my ct, GIS

Hai loi chnh: hiu ng Pockels v hiu ng Kerr

Hiu ng in quang: Hin tng lng chit (tia sng i qua vt liu b tch lm hai, ngvi hai vn tc khc nhau hay ch s khc x khc nhau) xy ra trong mt s vt liu khi vtvi hai vn tc khc nhau hay ch s khc x khc nhau) xy ra trong mt s vt liu khi vtliu t trong in trng. Ch s khc x (chit xut) i vi mi thnh phn trc giaoca phn cc quang ph thuc vo in trng theo:

n=n0 +aE+bE2 + Cc thnh phn bc cao E3 t nh hng n n nn khng xt

Chit xut khi kh

Chit xut ph thuc tuyn tnh vo bnh phng E (hiu ngkhi khng

c EH s ca hiu ng in quang

Chit xut ph thuc tuyn tnh vo E (hiu ng Pockels

phng E (hiu ng Kerr)


(hiu ng Pockels

Cm bin Pockels Nguyn tc: Khi mt ngun sng phn cc tuyn tnh (c hai thnh phn trc giao ex v ey) x ylan truyn theo trc z qua mt tinh th Pockels (c hin tng lng chit do tc dng ca E). Vi vn tc lan truyn khc nhau lm cho hai thnh phn lch pha nhau mt gc:

= 0 +AE H s nhy ca tinh th Pockels

Gc lch pha khi E=0, thng thng =0

tinh th Pockels (ph thuc vt liu)

Cng sng khi ra khi h Pockels P0 (gm tinh th+cc phn cc vo v ra):

P0 = Pi/2(1+sin())Do nh nn sin()~ P0 ph thuc tuyn tnh vo E

ng dng: Cm bin in p Pockels tch hp trong cc ng dng: Cm bin in p Pockels tch hp trong cc thit b ca trm GIS, c th dng o in p DC, AC, xung st, PD trong cch in kh hoc in tch khng gian


Cm bin Kerr Nguyn tc: Tng t nh cm bin Pockels, gc lch pha t l vi bnh phng intrng (b qua hiu ng Pockels):

= 0+2rkLE2=BE2; rk: hng s Kerr, L: ng i hiu dng ca nh snh; B: h s nhycu tinh th

H s nhy caGc lch pha khiE=0, thngthng 0=0

H s nhy cat bo Kerr (phthuc vt liu)

Sau khi i qua phn cc th hai cng sng u ra t l vi cng sng u vo Sau khi i qua phn cc th hai, cng sng u ra t l vi cng sng u vo theo quan h:

P0 = Pisin2(/2)= Pisin2(LrkV2/d2)

in mi lng thng c s dng trong cc t bo Kerr (Kerr cell): Nitrobenzen (rk=20.10-12 m/V2), nc tinh khit (rk=3.4.10-14), du my bin p (rk=3.5.10-15)


Cm bin t quang (magneto-optic sensors) ng dng: Dng o cng dng in (th nghim, o m v bo v trong HT) hoc cng t trng (kim tra nh hng n sc khe con ngi ca HT)

u im: c tch hp d dng vo thit b, cch in, chng n mn, nh gn, khng gy nhiu in t

Hiu ng Faraday: Khi mt nh sng b phn cc i qua mi trng t quang t trong t trng ngoi, mt phng phn cc b quay (rotate) mt gc t l vi t trng ngoi, gc quay (rad) t l thun vi cng dng in:

= K N I C d i

t thm t i H V d t S vng ca ng

= KvNtI Cng dng in

tng i Hng s Verdet (ph thuc vo vt liu, bc sng nh sng..)

S vng ca ng i nh sng xung quanh dy dn (dn dng in)

Nhc im: Nhy vi nhit mi trng do hng s Verdet ph thuc vo nhit



4. O CNG IN TRNG


o cng in trng (u o) Mc ch: E l mt trong nhng thng s quan trng nht trong thit k TB cao p (khng xy ra phng in, vng quang, cc b), l thng s nh gi tc ng ca HT cao p vi sc khe (quy phm Vit Nam: E

Phn III:

Cc phng php th nghim, gim st v chn

on cch inon cch in



Ti sao cn gim st & chn on cch in?

in p nh thng ca cch in ph thuc vo thi gian lm vic:


Cc phng php th nghim, chn on v gim st cch in

1. c tnh ng ca in mi


Hin tng phn cc in mi Khi t trong in trng cc lng cc trong in miKhi t trong in trng, cc lng cc trong in mi c hnh thnh (hin tng phn cc)

Cc loi phn cc: phn cc in t, phn cc ion, phn cc lng cc, phn cc lp tip gip. Mi loi ng i h h i i i vi mt ng gp cho hng s in mi tng i v tn

hao in mi cc tn s khc nhau

Tng cc vc t phn cc thnh phn to thnh vc t phn cc tng cng Pphn cc tng cng P

Trong min thi gian, mt in cm lin h vi in trng ngoi E v vc t phn cc P theo:


p ng in mi trong min thi gian Quan h gia vc t phn cc tng cng P inQuan h gia vc t phn cc tng cng P, in trng E, kh nng phn cc , hm p ng in mi f(t):

Mt dng in theo phng trnh Maxwell:

N i t kh i E0 (th i thi i t 0) Nu in trng khng i E0 (thay i thi im t=0):


ng dng p ng in mi trong min thi gian Ch s phn cc (polarisation index): PI=I1/I10Ch s phn cc (polarisation index): PI I1/I10PI>2: good; PI=1,252: fair; PI=1,11,25: questionable; PI=1 1,1: poor; PI

ng dng PDC trong chn on my bin p* (1)

*Supatra Bhumiwat, 2004 Weidmann-ACTI Annual Technical Conference


Supatra Bhumiwat, 2004 Weidmann ACTI Annual Technical Conference

ng dng PDC trong chn on my bin p (2) Cch in gia cc cun dy (U=100V)Cch in gia cc cun dy (U 100V)

My mi


p ng in mi trong min tn s Phng trnh Maxwell chuyn qua min tn sPhng trnh Maxwell chuyn qua min tn s

Nu cch in l tng (khng c in tch t do): J()=i0() E() Trn thc t lun tn ti in tch t do v cc hiu ng tng ng (pht nng) Trn thc t lun tn ti in tch t do v cc hiu ng tng ng (pht nng)

So snh vi J() trn:

Gc tn hao in mi tan=JR/JC=/ hay l:


Gc tn hao in mi tan JR/JC / hay l:

Gc tn hao in mi

nh ngha gc tn hao in mi (tip): Gc gia U v I trong trng hp l tng l 90o

Mch tng ng song song (c s dng nhiu hn):

Mch tng ng ni tip:

Trong c hai mch tng ng, mi tr s tan o c ng vi mt tn s


Ngun gc ca tn hao1 Tn hao do in dn (hoc R) tng khi tn1. Tn hao do in dn (hoc R), tng khi tn

s gim

tan 2. Tn hao do lng cc, do cc lng cc xoay gy ra ma st vi phn t bn cnh, khi tn s tng th

Tn s

p , gma st tng v tn hao t max. Khi tn s tng qu cao cc lng cc khng th theo kp chiu in trng tn hao gim

3 Tn hao do hin tng tip gip gia mt cch in3. Tn hao do hin tng tip gip gia mt cch in l tng v cch in c tn hao (e.g: cch in kh ni tip vi cch in rn)

tan trng hp ny c khi =0 v =, tan =0. Hnh

T

dng t nhn hn trng hp 2


Tn s

Ngun gc ca tn hao (2)4 Tn hao do phng in cc b: bt u xy ra khi U>U (in4. Tn hao do phng in cc b: bt u xy ra khi U>U0 (in

p bt u hnh thnh PD)

tan

U0 U

Phn tch tn hao: Tn s v in p nh hng rt ln n tr s tn hao, ngoi ra nhit cng nh hng quan trng

n tan (lng cc ly thm nng lng t nhit v lm gim nht ca cht lng)


Cu ScheringMc ch: o tn hao v in dung trong min tn s Mc ch: o tn hao v in dung trong min tn s

Nguyn tc: Cu cn bng khi Z1/Z3=Z2/Z4 Nhnh cao p: Vt cn o (x), t mu CN, (t kh SF6

t t h kh k th h ip sut cao, tn hao khng ng k, c th chu in p n MV, PD free)

Nhnh h p: in p ri vi trm V, R3 v C4 c iu chnh t cn bngiu chnh t cn bng

Gi thit: mu l mch Rx ni tip Cx, iu kin cn bng thit lp t gi nh ny, ngha l:

iu kin cn bng: kim in k G ch 0:u c b g G c 0

Cn bng phn thc v o: Tan c tnh:


Cu Schering (2)Thng thng R t trong hp c tr s gii hn Thng thng R3 t trong hp, c tr s gii hn di 10 000 hn ch C k sinh

R4 thng l bi s ca 1000/ c trc tip tanNhc im: in dung k sinh im b v d vi Nhc im: in dung k sinh im b v d vi t (nhnh h p) v chiu di y ni vi nhnh HV iu kin cn bng b nh hng s dng vi thit b ni t Wagner (Wagner earthing device)device).

Nguyn tc ca WED: a in th ca v cp ni vi nhnh HV v in th ti im b cp t t bv d bng nhau in dung k sinh ca cc im ny b loi b. Khuch i c h s K=1 khng c dng in dung gia b v d vi mn chn

Phm vi: ng dng n 100kHz, in dung o c t 1pF n 1000F ( chnh xc 0,1%), tan t 10-4 n 0,1 ( chnh xc 10 4)


n 10-4)

Dng cu Schering trn thit b thtThit b tht c mt cc c ni t cng (v thit b) nh MBA cp Trng hp Thit b tht c mt cc c ni t cng (v thit b) nh MBA, cp Trng hp ny s dng cu Schering ngc (inverted Schering bridge): nhnh cao p c ni t

Nhnh h p (cc phn t bin i) ni vi in p cao v t trong lng Faraday cng vi ngi vn hnh, hoc c iu khin t xag ,


Gi tr ca tan trong thc tTr s tuyt i: Cc thit b in c tr s tan nm 3 mc: Tr s tuyt i: Cc thit b in c tr s tan nm 3 mc:

1. Cp PE tn hao thp v my ct kh: 1.10-4 10.10-4 . Chi ph ca tn hao khng ng k

2 M bi h i b i t d h i ( bb )2. My bin p cch in bng giy tm du, cp cch in cao su (rubber), ph kin cp, cch in xuyn: 20.10-4 50.10-4. Khng c nguy c phng in nhit, chi ph tn hao ch ng k in p 400kV. Hin tng lo ha xy ra nu tan > tr s ny

3. tan> 100.10-4 , tr s ny c coi l qu cao vi thit b cao p. Thng xy ra cch in PVC vi in p n 6kV. tr s in p >6kV, tn hao c gi tr ny c th gy ra phng in nhit v khng chp nhn c

nh hng ca in p: gc tn hao thng c kim tra cc tr s in p khc nhau v tnh tan, iu kin: tan< 5.10-4 vi u=1/2U0 v 2U0. Ln hn tr s ny c coi l cch in cn phi thay th


Phn tch ph in miCc hin tng phn cc dn in ng gp khc nhau vo tr s (in dung) v tn Cc hin tng phn cc, dn in ng gp khc nhau vo tr s (in dung) v tn hao cc tn s khc nhau

Nguyn tc: t U ( cc tn s khc nhau), o I, tnh in dung phc

Di tn: t 10-4 Hz1GHz, in p n 30kV (dng vi khuch i)


Phn tch ph in mi (2) Nhn dng cc c ch gy ra tn hao tng tn sNhn dng cc c ch gy ra tn hao tng tn s


Cc phng php th nghim, chn on v gim st cch in

Phng in cc b


Cc loi phng in cc b

Phng in bn trong: Phng in bntrong cc bc kh ca cch in rn, bckh gia in cc v cch in (do incc b bong) do hin tng cy incc b bong), do hin tng cy inetc.

Phng in b mt: Phng in dctrn b mt cch din, v d phng dcgb mt cc foil trong s xuyn kiu t

Phng in vng quang: Phng inxy ra cc im nhn kim loi (c phat v cao p) Gy ra nhiu khi tht v cao p). Gy ra nhiu khi thnghim PD ca thit b

Tc hi: e v cc ion c nng lngcao gy chuyn ha vt liu, c bit AC. PD trong PE c th gy phng inchc thng trong vi ngy


Cc phng php o PD

D t t D i (d PD) t b i t ( h Da trn cc nguyn tc: Dng in xung (dng PD), o tan, bc x in t (nhsng), m thanh (sng m), tng p sut kh, phn ng ha hc

Cc hn ch: tan : ionisation knee kh pht hin do ln vi cc dng tn hao do phncc, nh sng: ch mi trng trong sut; p sut kh (relay Buchholtz): nhy km;cc, nh sng: ch mi trng trong sut; p sut kh (relay Buchholtz): nhy km; o m thanh ( n): lm vic tn s >30kHz. tn s ny ting n mi trng b loib nhng suy gim m thanh trong khng kh li rt ln.

Phng php ph bin nht: phng php o in (in tch, dng in)


Mch tng ng ca PD

Kch thc vt l:

Gi thit mu np ti Va v khng ni vo ngun na, kha S ng ng ngha vi Ccphng in v dng ic(t) s gii phng qc=CcVc. St p trn AB sau khi phng:

Tr s ny khng c thng tin v qc, nhng t l thun vi CbVc, Cb tng nu kch thcbc kh tng


Va o c nhng rt nh do Cb/Ca khng xc nh khng s dng i lng ny

Phng php o trc tip (straight detection)

Z: tng tr t nhin ca cp ni, Ck: in dung tng h vi PD free HV; gi cho U trnmu khng i trong thi gian PD

Khi PD trong mu, Va c b hon ton v in tch dch t Ck sang Ct bi i(t) (nuCk>Ct):

in tch biu kin (v khng bngin tch trong C )in tch trong Cc)


Phng php o trc tip (2)


Phng php o trc tip (3)


Phng php time resolved detection o c xung thc ca PD, thi gian c ns, xung c khuch i vi di tn t 100

MHz n 500 MHz. Xung c hin th trn oscilloscope nhn dng c PD (phng inbn trong, b mt hay vng quang)

Dng vi mch o trc tip nhng c khuch i: i=f(t) Dng vi mch o trc tip nhng c khuch i: i=f(t)


Gi tr PD cho php ca mt s thit b


Mu phng in (discharge pattern) Mi thit b, hnh dng ni b PD, qu trnh vt l, ha hc km theo PD u c mt dng

phng in khc nhau. Cn thit lp mu phng in i vi tng loi, tng thi im o so snh v chn on tnh trng cch in

Cc thng s quan trng thit lp mu: ln tng (rate of rise) Cc thng s quan trng thit lp mu: ln, tng (rate of rise)


Hiu chnh o PD (calibration) Rt kh o chnh xc PD do nh hng ca nhiu yu t:

Hiu chnh bng cch bm in tch (in p) chun vo b o PD


o PD cho cp

Cp phi c ct in (de-energized), in p t vo c tn s thp vo mt u cp(cng vi b pht hin PD), mt u h mch

Chnh lch thi gian gia hai sng ti b pht hin s xc nh v tr c PD

C th chn on chnh xc cho di t vi m n vi km


o lng s dng k thutquang trong thit b cao p


Phn IV: Th nghim thitb in cao p


Th nghim thit b in cao p

Th nghim trn mu thit k (type test): Kim tra cht lng sn phm ang trong khuthit k (hoc thit k li) v pht trin (trn prototype)

Th nghim trn tng thit b (routine test): Kim tra cht lng trn tng sn phm saukhi ch tokhi ch to

C nhiu hng mc th nghim: Chu trnh nhit, in-c, c, in. Ch cp n cchng mc th nghim lin quan n in

CFO (U ) cho mt dng in p bt k BSL (Basic Switching Impulse Insulation Level) CFO (U50%) cho mt dng in p bt k, BSL (Basic Switching Impulse Insulation Level) v BIL (Basic Lightning Impulse Insulation Level): Statistical cho c t phc hi vConventional cho c khng t phc hi


Th nghim cch in ng dy

Cch in kiu pin

Cch in kiu postCch in kiu post

Chui no

Chui


Chui

Th nghim cch in ng dy

Th nghim in p xung:1. in p xung chu ng (Impulse withstand voltage test): t mt tr s in p

xung chun (1,2/50) ln cch in kh (c hai cc tnh). Nu khng c phng inb mt hoc chc thng (puncture) pass. Nu 2/5 c phng in fail. Nu 1/5 c

Th nghim in p xung:

phng in t ln 10 xung lin tip, nu pass OK tr s in p xung ny2. in p xung xy ra phng in b mt (flashover): Th nghim ging nh trn mt in p xc nh vi xung chun (1,2/50) xc nh tr s in p 40% v 60%, hoc 20% v 80% (Do 50% kh xc nh) Ly trung bnh ca cn trn v cn dihoc 20% v 80% (Do 50% kh xc nh). Ly trung bnh ca cn trn v cn di xc nh min. Tr s chnh xc xc nh theo phng php step and down (tnghoc gim 5% mi ln)

Th nghim in p tn s cng nghip:1. Th nghim kh v t: in p c gi tr xc nh (ng vi in p chu ng

kh v t) t ln cch in v duy tr trong vng 1 pht.

2. Nu cch in c th in p phng in b mt vi iu kin ma nhn to, ma cn c cc tnh cht : i)Tc phun 310% mm/pht; ii)hng ma 45o ;

iii)in dn 100S; iv) nhit nc: 15oC


Th nghim cch in xuyn (bushing)

Th nghim in p xung:1. Xung y (full wave): Mt trong hai cc

tnh. 5 xung t ln, nu 2 fail fail, nu 1 fail th tip 10 xung

Th nghim in p xung:

2. Xung ct (chopped wave) v xung ng ct: Ch th nghim cho in p 220kV tr ln. Cch th ging nh full wave

Th nghim in p tn s cng nghip:1. Th nghim kim tra in dung v tan : Bushing c t nh khi lm vic hoc

nhng trong du Phn cao p ni vi HV terminal ca cu Schering phn ni tnhng trong du. Phn cao p ni vi HV terminal ca cu Schering, phn ni thoc v (MBA, TU) ni vi phn cc pht hin (detector side) ca cu. C v tan c o nhiu mc in p v so snh vi quy nh

2. Th nghim PD

3. Th nghim in p chu ng 1 pht: kh v t


Th nghim cp

M th t 50 10 Mu th t 50 cm n 10m1. Th h s tn hao (Dng cu Schering): tan o cc

tr s 0,5; 1,0; 1,66 v 2Upha .

2. Routine test: Cp c t in p 2,5Upha trong 10 pht khng c h hng.

3. Type test: Th nghim c DC v xung. Th DC: in pth 1 8U h t h t 30 Th thth =1,8Upha, cc tnh m trong vng 30. Th xung: theoin p xung yu cu

4. Th PD: xc nh PD map v thi gian s dng

5 Th t i th (lif t t) E Kt 1/ K l h h th 5. Th tui th (life test): E=Kt-1/n ; K l hng s ph thucin trng v vt liu, n:ch s tui th, ph thuc vo vtliu (Thi gian th t 1h n 1000h)


Th nghim my ct

1 Th trc tip (direct test) s dng ngun l my1. Th trc tip (direct test) s dng ngun l mypht dng ngn mch. Make switch: ng dng ngnmch; backup breaker: ngt dng ngn mch. intr: thay i h s cng sut ca dng nm; inkhng: thay i dc ca thnh phn dc ca dngkhng: thay i dc ca thnh phn dc ca dngnm. in dung: thay i dc ca in p phc hi

2. Th trc tip dng in li: u im: Th viiu kin tht (dng ngn mch, ng ng dykh ti h CB hi hit khng ti, ngn mch gn CB, hiu ng nhit cadng nm). Nhc im: Ch th c vi kh nngc th ca li, ch tc ng iu kin ti thp..

3. Th hn hp trong phng th nghim: th c vi3. Th hn hp trong phng th nghim: th c vidng nm v in p phc hi c cung cp t haingun


Th nghim my bin p

1. Th PD: Th trn mi u ra ca MBA. in tch biu kin khng c vt qu104 pC

2. Th nghim in p xung, mc ch xc nh mc cch in xung hay in p phngin (breakdown) cho cc cch in: gia cc vng dy (cch in ph) gia cc cunin (breakdown) cho cc cch in: gia cc vng dy (cch in ph), gia cc cundy, gia cun dy v v (cch in chnh); v in p phng in b mt ca cchin xuyn. in p xung c th c vi full wave v chopped wave (t 3s 6 s). Cc cun khng th c ni ngn mch trnh in p cm ng dao ng.

3. Quy trnh th nghim in p xung: i) 75% ca BIL, full wave; ii)100% BIL; iii) 2 chopped wave ca 100% BIL; iv) full wave ca 100% BIL v v) 75% ca BIL


dlca va ktkph upadated 10_2013-2

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