Note: Descriptions are shown in the official language in which they were submitted.
9~9 ~N T~ A`P~ $`13~ 3
.~ ~T~TRANSLA-rlO3~1
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:~;' Method and arrangement for detecting fault~ in pow~r
converter in~tallations
.~ The invention relates to a method and an arrange-
~i. 5 ment for detecting fault~, in particular di~charge
:;;
.. j faults, in a converter arrangement.
.j, In power converter in~ allation~, in particular
;~ high-voltage direct current transmi~ion ~ystem~, partial
.~ or glow discharge~, ~lowing and sparking~ right up to
'~ 10 rapidly extingui~hing arc flashover~, can oecur a~ a
result of in~ulation, linP or contact faults. ~h~ fault
~ite~ heat up ther~by, which can re~ult in the in3talla-
ion catching fire~
The mekhod~ hitherto known for preventing fire~
.~ 15 in in tallation~ of thi~ typ~ ar~ ba-~ed on mLnimizing the
damage by dete~ting a fire or heat ~ource and
~ubs~quently shutting down the in~tallation. Smoke gas
and heat sen~ox~ ar~ u~e a~ detectors, but their
re3pon~e behavior and sen~itivity are not ~ufficient to
20 pexmit clear and preci~e fault detection7 It has there
fore alr~ady b~en propo~ed that light-e~ltting fault~ be
detected by means of opto~lectronic light ~n~or~, which
.~ mu~t be di~tributed in large rlumbers throuyhout the
; installationr or by mean~ oiE highly 3l3ni~itiv~ video
25 8y~tem8. With arlother method, the confii~terlcy o~ the air
. ri3ing abc)ve thQ installation i~ monitcsred with the aid
of la~3er ~y~tems ila order to det~c:t fir~ or h~at source~O
:~ Owing to the pr~ent-day compac:t design of power
.~ . converter in~tallation~ a~nd 1:heir arrarlgem~nt in a
~ 30 building, however, the~e known ~y~tem3 constitute a
:i , dir~ct intenrention in th~ insulation coordination and
j ! :
;j~, can considerably ln~lu~3nce poten~ial pro:Eiles of the
. ~ in~tallat ion in a n~gative ma~mer D
The object of the invention i~ to provid~ ault
35 detection in convert~r axran~m~nt~ which i~3 suitable for
'3 th~ early detection of faultY that ~:ould le!ad to a fire.
Thi~ object i~ achieved accordinq l~o the i~aven-
tion hy the f~3~ture~ of claim 1. Simple, reliable deltec-
tion of fire= causing fault~ 18 po~ible in thi~ way.
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Already existing elec~rical measuring point~ and trans-
ducers can be used with this method. Since there is no
optical fault detection, erroneou3 triggering a3 a re~ult
~, of ou~side light and contamination is precluded. With
^! 5 this method it i~ possible to det~ct even ~mall partial
di~charges in the converter arrangement before there i9
any ri~k of fire at all.
During frequency analy3i9 ~ an increa8e of non
I characteristic harmonic ~ignal components in the fre-
quency spec~rum and~or an increase in interhanmonic
signal componentR in the frequency spectrum are advan-
tageously observed. In this way improved fault detection
.is possible. The inventor ha namely rPcognized that in
particular ~aid signal components are increase~ in the
case of fault~ in co~verter arrangement~ and are there-
, fore particularly well-suited for fault analy9i~.
The ~onverter arr~ngement may compri~e two
converter3 here, th~ signal being picked up betwee~ the
: converters. In this ca~e, the pick o~f for the signal can
, ~0 be preferably arranged on a direct current link of th~
converter arrangement. The converter arrangement
preferably designed here as a high voltage direct current
transmi3sion system. In accordance with claims 4, 5 and
6 to 8, a ~pecific fault analysis and evaluatio~ can be
2 5 advantageou~ly perf ormed, thereby providing an improv~-
ment in operation with re3pect to early fault det~ction.
In addition, a weighting of co~bination~ of frequency
componen~ advantageou~ly po~3ible.
~he object i9 further achiev~d according to the
,1 30 features of claim~ 12 to 20 which relate to a protective
~ ! Ideyice ~rving for the execu~ion o~ the abovementioned
q method. In co~trast to optical prot2ctive devic2s, no
al~eration i~ required to the de~ign and con~truction of
th~ converter arrangement when this prstective device i~
used ~ince the protectiv~ device i~ ~Lmply connected ~o
the converter arrangement via electrical conn~ction~. The
;, prokective device preferably ha~ an evalllation devi~e
with fuæzy logic.
~xemplary embodiment~ and ~dvantaye~ of the
t
invention are explained in greater detail below with
reference to the drawing by way of example, in which:
FIG 1 ~how~ a circuit arrangement for detecting faults
~:, in a converter arrangement,
5 FI& 2 show~ a further circuit arrangement with detailed
illustration of a prote~tive device, and
~' FIG 3 show~ an evaluation logic diagram.
.. . ,i
:'l The circuit arrangement in FIG l 3hows a protec-
tive device l which i~ connected to a converter arrange-
10 ment 2. The converter arxangement 2 illu~trated by way of
example conneets two network~ 3a, 3b to one another. The
converter arr~ngement 2 has, for example, two converter~
4a, 4b, which each contain an associated control device
6a, 6b. The two converter~ 4a, 4b are connected to one
15 another via an intermediate circui 8. A signal S of the
converter arrangement 2, pxeferably the ignal of the
-i~ int rmediate circuit 8, is picked up via a signal trans-
mitter 10 and ~ed to the protective device 1.
The protective devicP 1 contain~ a frequency
I 20 analyzer 12, ~o which the ~ignal S i~ fed. The frequ~ncy
a~alyzer 12 i~ coupled to an evaluatio~ device 14 which
~ permit~ evaluation of the ~requency 3pectrum me~sured by
,. the frequency analyzer 12.
~he signal S has a characteristic frequency
, 25 spectrum during ~tationary operation of the converter
,.!,' arrangement 2. However, if ault~ occur during operation,
, or example a8 a re~ult of glowing or sparking, then
the~e fault~ are expre3sed as a change in the frequency
spectrum of the ~ignal S. The prot~ctive device 1 recog
'.!!; 30 nizes the~ie change~ a~ being caui~ed by a fault and
, laon~squently generat~ a fault ~ig~al F5 which iQ output
at an output 16. Freque~cia~ i~ th~ k~z range are prefer-
ably analyzed here and u~ed a~ aul~ ~riteria. ~lterna~
.~ tively, or in addition, the fault ~ignal may al~o be fed
:3 35 to an indicating device 18, which then ~ignal~ithe ault.
;~
: The fault ~ig~al FS can ~hen b2 fed ~o fur~her elec~rical
'~ d~vice~ in order to initiate elimination of the fault
3 that h~ oc~urr~d, for example initiat~ r~s~ricted
operation. In FI~ 1, for example, the output~ 16 are
, ;l
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connected to the control device~ 6a, 6b of the converter~
4a and 4b. In thiR way, for ex~mple, a ~hutdown of the
converter arrangement 2 or else a voltage-lLmiting
measure, which in turn re~ults in faul~ ~uppre~sion, can
be initiated.
~, Mea~urement ~ignal~ from line-commutated con-
verter arrangement~ employing valve technology (for
~ example thyri~tor~ u~ually have a frequency ~pectrum
j3 which preferably exhibits multiple~ of its pul~e number
I. On the alternating voltage ~ide, in this ca~e charac-
, teristic frequencies of (~Ixn) ~ 1) multiple~ occur (for
example in a 12-pul~e circuit. 11, 13., ~3., 25.~ 35.,
. ... etc.), wherea~ on the direct voltage side (Ixn)
multiple~ occur t12, 24, 36, etc.~.
In additionl non-characteri3tic frequencies ox
~o-called interharmonics occur in the freguency spectrum,
these being produced as a re~ult of asym~letrles withi~
the converter arrangement and being negligibly small
during normal operation.
If the~e uncharacteristic operating ~requencies
in the frequency spectrum occur during operation, then
thi~ is an indication that there i~ a fault in the
converter arrangement. In particular in the case of
di~harg2 fault~ of any kind, a broadband frequency
spectrum namely occurs, whi~h i8 detected and evaluated
with the pre~ent method and the prot~ctive device 1
operating in accordance there~ith. In this way it i~
po~sible to detect even very 3mall discharge~ and take
mea~ure~ to pxevent fire.
FIG 2 ~irst of all ~how~ a co~verter arrangement
i , 1 2a whi h i~ desi~ned a~ a hi~h-voltage direct current
tran3mis~ion ~ystem ~back to-back link or long-di~tance
transmission). I~ connects two network~ 3c; 3d designed
as three~pha~e ~ystem~, in which, for example, in the
ca~ of pow~r being tran~ported ~rom network 3c to
network 3d the conv~rter 4c i3 design~d as a rectifi~r
. and the converter 4d i~ de3igned a3 an inv~rter. The
intermediate circuit 8a carriea a direct current signalO
At lea~t one ~moothing reactor 20 i8 additionally
,~
~, ~ s
. inserted in the intermediate circuit 8a. The ~ignal S of
`~:"f the intermediate circuit 8a i~ fed a5 mea3urement 3ignal
.; Sl, S2 to ~he protective device la via 3ignal transmltter
lOa, lOb.
i 5A fa~t Fourier transformation element (FFT),
which perform~ the actual analy~is of the frequency
~ spectrum of the ~ignal S, i~ an e~sential function
.~f element of the protective devic~ la. A design which
provides for a possible measurement value conditioning
for the FFT element 22 i~ shown here by way of example.
Accordingly, the measurement ~ignals Sl~ S2 are first fed
to ~ multiplexer 24. This i~ favorable i~ only one
,.~f analog-digi~al conver~er i~ to he provided for the
¦ processing of a plurality of measurement values. The
~ignal output by the multiplexer 24 i8 then fed to a
high-pa~s filter 26 for ~uppres3ion of a direct component
,~ and i~ sub~equently amplified by an amplifier 280 An
~'~ anti-aliasing filter 30 matched to a sampling frequency
of the analog-digital ~onverter can b~ provided f or
2 0bandwidth limitation .
, Thi~ is followed by the analsg-digital converter
32 which i~ u~ed for digitlzing the ~ignal S. It may al50
contain a ~o~ Plled ~ample and hold element. The
digitized measurement data are stored in a high~peed
25memory 34 which i~s marlaged by a proce~or 36 a~signed to
the FFT element 22.
Depending orl the sampling increment, window width
and arrangement selected, the FF~ analysis in the FFT
el~ent 22 ~uppli~ a frequency ~p~ctrum which can then
. 30 be evaluated frequency~electively by the evaluation
I ~evice 14. In this case the non-characteri~tic and
,`~ interharmo~ic current component~ cf th2 ~ignal S can be
used as a fault criterion either 3eparately or as a
i weighted 3um. A monitor 38, a plotter 40 or a data memory
42 can be provided for signaling or for ~utputo Further-
more, the fault si~nal FS may al~o be forwarded directly
, to a higher-ranking protection ~y~te~ for further fault
handling or else to the control device~ 6c, 6d of the
converter3 4c, 4do
,~.~
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A program controller 44 may be provided for
~ higher-ranking open-loop or closed-loop control, thi~
:j b~ing synchronized with a higher-ranking installation
~ controller and coordinati.ng the entire mea~urement value
``3 5 recording and evaluation. Additional input~ or evalu-
ation~ can be performed by means of an operator panel 46.
~`~ The program controller 44 can also be used to generate
. assigned fault signal~ dep~nding on the respectiv~
selected changes in the frequency ~pectrum, so that
., 10 depending on the type of fault which i8 reflected in
different chanqe~ in the fre~uency ~pectrum, different
reactions of the converter arrangement ar~ poY~ible.
The method i8 not dependent on the type of
~ converter arrangement (for ~xample, monopole, bipole,
:.~, 15 multi-tenminal, hack to-back link, long-distance tran~-
:~. mission), Yince it only evaluates a common ~ignal. The
follswing advantages emerqe in practice:
- the existing mea~uring point~ and transducers can be
~ used for spen~loop a~d closed-loop control of the
.~ 20 converter arrangement;
~ no alteration i5 made to the design and con~truction of
,~
`~ valve towers or operating rooms; and
erroneou~ triygering as a re~ult of out~ide light,
contamination or the like i8 precluded~ in contra~t to
optical devices for example.
, The frequency analysis may also be performed with
. the aid of fuzzy logi~. For thi~, for example, the
evaluation d~vice 14 may contai~ fuæzy logic which i8
; uqed to welght the ~ignal cvmponent~ in the frequency
~pectrum~ In thi way it i~ possible to recogni2e
~ I ~ critical frequency 3pectra a~ being causad by a fault.
.~ ~his applies in particular to ~ignal combination~ where
the re~pective individually oc~urring frequencie~ do no~
them~elves indicat~ a fault, but a fault ca~ be detected
from the weighted ~um. A diagram o~ thi~ i~ shown in
,t FIG 3, which how~ a w~ighting of ~ignal component5 by
way of example. The frequency f and ths weighting G are
plotted on tha diagram axe~. ~he curve ~ ~hows th~ cas~
during normal operation. a and c repre~en~ a ma30r a~d a
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:~ minor fault respectively, for exiample. The weighting mu3t
be matched to the specific applicatiorl.
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