134 Ad ances in Elec ical and Elec onic Enginee ing
HIGH-FREQUENCY ANALYSIS OF THREE-WINDING
AUTOTRANSFORMERS 400/121/34 kV
M. Gu en, M. B and
1)
, R. Polanský, P. P os
2)
1) Dep o Measu emen s and Applied Elec ical Enginee ing, Uni e si y o Žilina,
Uni e zi ná 1, 010 26 Žilina, Slo ak Republic, E-mail: [email p o ec ed]iza.sk
2) Facul y o Elec ical Enginee ing, ZU Plze,
Uni e zi ní 26, 306 14 Plze, Czech Republic, E-mail: [email p o ec ed].cz
Summa y This a icle deals wi h a desc ip ion o me hods o an expe imen al analysis conce ning he ac ual condi ion o
windings and magne ic ci cui o he au o ans o me , which is equi ed in powe ansmission companies all o e he wo ld.
1. INTRODUCTION
Conside ing a signi icance o powe h ee-
winding au o ans o me s (see Fig.1) in he elec ic
sys em, hei p ice and possible damages a ising in
acciden s, i is necessa y o pay a en ion o highe
p e en ion o hese de ices. Windings o he au o-
ans o me s should be designed o a oid a ious
mechanical o he mal de e io a ions caused by
sho -ci cui cu en s occu ing in ope a ion.
Besides he pe manen de o ma ion e ec s o
sho -ci cui cu en , he e is also g adual aging
p ocess o he elec ical de ice, which can wo sen i s
mechanical p ope ies. Hea shocks can cause de-
c ease o mechanical s eng h o ans o me and
consequen unexpec ed damage o ans o me du -
ing he ope a ion.
To p e en a damage s a e o ans o me s, we
pe o m di e en ypes o he measu emen s ha
should illus a e an ac ual condi ion o he measu ed
equipmen . I is he e o e impo an o choose a
sui able diagnos ics o he igh p edic ion o such
condi ions.
Fig.1 The au o ans o me 400/121/34 kV
This a icle deals wi h a desc ip ion o me hods
o an expe imen al analysis conce ning he ac ual
condi ion o windings and magne ic ci cui o he
ans o me , which is equi ed in powe ansmission
and powe dis ibu ion companies all o e he wo ld.
2. THEORY OF SFRA METHOD AND ITS
IMPORTANCE IN TRANSFORMER
DIAGNOSTICS
SFRA me hod belongs o cu en mos e ec i e
analyses and allows o de ec he in luences o sho -
ci cui cu en s, o e cu en s and o he e ec s dam-
aging ei he winding o magne ic ci cui o he ans-
o me . This all can be pe o med wi hou a neces-
si y o decomposi ion o de ice and subsequen
winding damage de e mina ion, which is e y ime
consuming.
The me hod o he high- equency analysis
(Sweep F equency Response Analyze – SFRA [3])
is also one o he me hods o undisassembling diag-
nos ics o ans o me s. No in e en ion o he con-
s uc ion o es ed de ice is demanded, he whole
measu emen is pe o med on de ached de ice (no
unde he ol age). This me hod is applicable mainly
o de e mina ion and measu ing immedia ely a e
he manu ac u ing o de ice, i.e. o measu ing o
e e ence alues. These pa ame e s a e consequen ly
compa ed o he o he measu emen s pe o med on
he ans o me , which is decommissioned, a e he
damages o e isions o ans o me e c.
The e is possible o de ec by SFRA:
 a de o ma ion o winding and i s mo e-
men s,
 a sho -ci cui ed u n o opened winding,
 a loose swi ching sys em,
 a damaged swi ching sys em,
 a co e connec ion p oblem
 a pa ial b eakdown o winding,
 a co e mo emen o i s w ong g ounding.
Resul s measu ed on he new ans o me can be
used as he e e ence pa ame e s o u he com-
pa ison wi h alues measu ed la e a e ce ain
ope a ion ime o he ans o me . They can be also
compa ed wi h he es esul s pe o med a e he
ans o me b eakdown (o a e he n-sho -ci cui s)
o epai o i can be used as a diagnos ic es , when
ib a ion senso s indica e some po en ial p oblem in
ans o me .
High- equency analysis o h ee winding au o ans o me s 400/121/34 kV… 135
SFRA as a one o he mos p edic able me hods
is based on unc ional high- equency gene a o and
spec al eco ding analyze p inciple, which a e se
up and con olled by compu e . This me hod is used
also by M5100 measu ing sys em (see Fig.2) con-
s uc ed by Ame ican DOBLE company [3].
Fig.2 DOBLE M5100 measu ing sys em
Acco ding o [2] SFRA me hod de e mines he
ans o me esponses in a ime o equency a ea.
The ime esponse measu emen p o ides cu e
de e mina ion o he ime esponse o he speci ic
ol age impulse applied o winding inpu connec-
ion. The equency esponse measu emen consis s
in de e mina ion o ampli ude e en ually phase e-
sponse o he ha monic ol age o a iable equency
applied o winding inpu . While he ime esponse is
he eco d o ime beha iou o ol age, equency
esponse is he ampli ude esponse dependence on
equency.
A ela ion be ween he esponse and he winding
condi ion is de ini e, o he wise i is complica ed. I
is impossible o expec he assessmen o conc e e
damage o winding om di e ences in esponse
beha iou s. The measu emen esul s lead us only o
a s a emen o he ac ha some change o winding
condi ion eally occu ed. Such es esul s a e e y
help ul o decide, whe he i is una oidable o open
and e ise he ans o me o no .
3. MEASURING PRINCIPLES
The beha iou o ans o me winding esponse
e lec s e.g. elec omagne ic couplings be ween he
winding and ans o me ank, also be ween he
p ima y and seconda y (e en ually e ia y) winding,
be ween he windings o pa icula phases o be-
ween u ns hemsel es o pa icula windings.
The powe ans o me measu emen equi es a
se ing up o he equency ange om 10 Hz o 2
MHz, whe eas he e is necessa y o ollow he igh
measu ing echnique o p e en a ious inaccu acies
and aul s. Acco ding o [2] and [3], measu ing
echnique o h ee-winding au o ans o me
400/121/34 kV (Fig.3) is as ollows (see Tab.1).
Fig.3 The
h ee-winding au o ans o me 400/121/34 kV
es ed by SFRA be o e i s ac i a ion
Tab. 1
1. OPEN CIRCUIT TESTS
400 kV 121 kV 34 kV
e ia y winding
Tes
1 Tes
2 Tes
3 Tes
4 Tes
5 Tes
6 Tes
7 Tes
8 Tes
9
A –
a B –
b C –
c a –
n b –
n c –
n 3 –
1 1 –
2 2 –
3
2. SHORT CIRCUIT TESTS
a-b-c
sho -ci cui ed 1- 2- 3
sho -ci cui ed 1- 2- 3
sho -ci cui ed
Tes
10 Tes
11 Tes
12 Tes
13 Tes
14 Tes
15 Tes
16 Tes
17 Tes
18
A –
n B –
n C –
n A –
n B –
n C –
n a –
n b –
n c –
n
Du ing he open ci cui es s a mechanical con-
di ion o es ed winding and e omagne ic co e is
de ec ed. The ollowing cu es ypical o his
measu emen p o ide us impo an in o ma ion
abou changes in he co e, which a e isible in low
equencies, while highe equencies e e o p ob-
lems such as winding mo emen s o u n- o- u n
aul .
Fig.4 illus a es a simula ion o g adual inc ease
o u n- o- u n aul s ia open ci cui es on au o-
ans o me 400/121/34 kV (see Fig.3) a ans-
o me aps o 1, 9, 13 and 17.
C
B
A
c b
a
1 1
2 1
2
3
N
Taps
400 kV
121 kV
34 kV
136 Ad ances in Elec ical and Elec onic Enginee ing
The applica ion o analysis o phase a enua ion
depending on equency is sui able o mo e com-
ple e e alua ion o winding condi ion. This analysis
enables o assess he p ocesses o winding mo e-
men s du ing he pa icula sho -ci cui s in luences.
Fig.4 Simula ion o u n- o- u n aul inc ease by
open ci cui es on au o ans o me a ans o me
aps o 1, 9, 13 and 17
P oblems wi h co e g ounding o sho ed lami-
na es in he co e will ypically change he shape o
he lowes sec ion o he cu e ( o 10 kHz). Mid
equencies ( om 10 kHz o 200 kHz) ep esen
axial o adial mo emen s in he windings and high
equencies indica e p oblems such as e. g. winding
knocking o p oblems wi h con ac s.
Du ing he sho ci cui es s only he winding
condi ion in p ima y o seconda y pa o ans-
o me is de ec ed. This measu emen no i ies elia-
bly o de o ma ion o inne winding and i s mo e-
men as a esul e ec s o sho -ci cui cu en s.
4. CONCLUSION
P oblem o he equency analysis o ans o m-
e s by SFRA me hod is e y comp ehensi e and i s
applica ion becomes in e es ing o many ans-
o me manu ac u e s and ope a o s. F om he long-
e m poin o iew he SFRA me hod is supposed o
be e y use ul and i p o ides enough in o ma ion
on es ed ans o me s. These ans o me s ha e
hei e e ence da a ob ained by he manu ac u e s,
sui able o he compa ison wi h u he da a o
pa icula ans o me .
SFRA es ing me hod ep esen s one o he mos
e ec i e al e na i e diagnos ic me hods compa ed o
isual check. This me hod allows o de ec he e -
ec s o he sho -ci cui cu en s, whe eas we a e
able o e alua e he mechanical s eng h ac ion on
he ans o me winding du ing p e ious ope a ion I
is also possible o iden i y he speci ic winding
phase, which has been mos ly in luenced by he
sho -ci cui cu en s, wi hou a necessi y o ans-
o me di iding, which would be e y ime consum-
ing.
The e is also possible o iden i y he size o pa-
ame e s o ans o me pa allel ci cui as well as
he posi ion o i s esonance equency om pa icu-
la cu es (see Fig.5).
Fig.5 Compa ison o ampli ude a enua ion [dB] and
phase cu e [°] in equency dependence (measu emen o
he same ans o me winding)
REFERENCES
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O o aní me ody ek enních cha ak e is ik
podmínkach oz oden penoso é sous a y
R, In Diagnos ika 05, Plze 2005
[2] Gu en, M., B and , M., Michalík, J.: Analýza
ans o má o o zhadom na úinky sk a-
o ých p údo , In Diago 07, Os a a, 2007
[3] h p://www.doble.com/p oduc s/sweep_ equen
cy_ esponse_analysis.h ml, 15. 1. 2007.
[4] Men lík, V., P os , P., Pihe a, J., Polanský, R.:
New Possibili ies o he Oil-pape Insula ing
Sys ems, In P oceedings o he 20 h No dic In-
sula ion Symposium. T ondheim: Tapi Aca-
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