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Signal
processing techniques for partial discharge site location in shielded
cables |
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Knapp,
C.H.; Bansal, R.; Mashikian, M.S.; Northrop, R.B. |
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Power
Delivery, IEEE Transactions on , Volume: 5 Issue: 2 , April 1990 |
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An
instrumentation package capable of locating partial discharge sites in
cables has been |
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developed.
The digitized partial discharge (PD) signals recorded from one cable end |
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consist
of a sequence of pulses whose separations contain information on the
relative |
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location
of the PD site. The signals are often contaminated by noise and undergo |
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substantial
attenuation and phase change as they travel though the cable and the
detection |
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system.
Moreover, overlap of two successive pulses is possible if the PD site is
close to |
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a
cable end. The authors describe and illustrate two techniques-maximum
likelihood (ML) |
|
estimation
and deconvolution-for extracting pulse separation from such a time series
of |
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noisy
and ambiguous signals. Both real and simulated measurements are used to |
|
demonstrate
the potential of these methods. A procedure whereby knowledge of the |
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combined
cable-instrumentation transfer function can be incorporated into the
maximum |
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likelihood
technique is also discussed. The ML method appears to be much more
effective |
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in the
presence of cable noise. The main disadvantage of the ML method is that
the |
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approximate
width of the wavelet or basic PD pulse should be known to give the best |
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compromise
between noise smoothing and peak resolution. This width can be determined |
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by an
impulse response test or by knowledge of cable length and parameters.
|
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Wavelet
analysis used in UHF partial discharge detection in GIS [gas insulated |
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Li,
Z.M.; Feng, Y.P.; Chen, J.Q.; Zheng, X.G. |
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Power
System Technology, 1998. Proceedings. POWERCON '98. 1998 International |
|
Conference
on , Volume: 1 , 1998 |
|
One of
the most important subjects in monitoring GIS is PD detection. The issue
is that |
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the PD
signal is weak and sensitive to external noise. In this paper, the
experiments of |
|
detection
PD in GIS using UHF technique is described. The results show that UHF |
|
method
is effective in detecting PD in GIS and avoiding the disturbance of
corona. |
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Nevertheless
very large corona, fluorescent tube or radio frequency noise nearby can
still |
|
disturb
the measurement. A method of signal processing by software is presented in
this |
|
paper.
Through the procedure of signal wavelet transform, signal noise extraction
and |
|
signal
reconstruction the signal is analyzed to determine the magnitude of PD in
GIS and |
|
Partial
discharge mapping in high voltage (HV) cable networks |
|
Shim,
I.; Soraghan, J.J.; Siew, W.H.; McPherson, F.; Sludden, K.; Gale, P.F. |
|
Electrical
Insulation Conference and Electrical Manufacturing & Coil Winding |
|
Conference,
1999. Proceedings , 1999 |
|
This
paper presents a new technique for locating partial discharges in HV
cables. The |
|
method
has been developed and used for on-line measurement of HV cable networks. |
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When
there is more than one PD site, the PD location procedure becomes
intricate. The |
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PD
patterns are processed to detect the individual PD locations. An analogue
model was |
|
built
to verify and test the technique proposed. The results of the PD generated
from the |
|
model
are presented and discussed. Real data from the field are later compared
to the |
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results
obtained from the model.
|
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Defect
classification based on Weibull statistic of partial discharge height |
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distribution
with wavelet preprocessing |
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Power
System Technology, 2000. Proceedings. PowerCon 2000. International |
|
Conference
on , Volume: 2 , 2000 |
|
Page(s):
1035 -1040 vol.2 |
|
The
paper describes a stochastic analysis performed using two-parameter
Weibull |
|
statistics
involving a scheme whereby the PD signals are decomposed using discrete |
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wavelet
transform. In a high voltage experimental setup, artificial cylindrical
voids were |
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made
in a Perspex column of 40 mm in length. The signals obtained from a corona |
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detector
were collected via an 8 bit oscilloscope with data storage capabilities.
The signals |
|
were
analyzed using PD height distribution (PDHD). The scheme presents itself
as a |
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multi-level
Weibull analysis to identify and quantify voids in solid dielectric
insulations |
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based
on nonultra wide band detection and wavelet aided signal processing.
|
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Detection
of wide-band E-M signals emitted from partial discharge occurring in |
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GIS
using wavelet transform |
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Kawada,
M.; Tungkanawanich, A.; Kawasaki, Z.-I.; Matsu-Ura, K. |
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Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 2 , April 2000 |
|
Recently,
diagnostic techniques have been investigated to detect a partial discharge
(PD) |
|
associated
with a dielectric material defect in a high-voltage electrical apparatus.
Gas |
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insulated
switchgear (GIS) is an important equipment in a substation, it is highly
desirable |
|
to
measure a partial discharge (PD) occurring in GIS which is a symptom of an
insulation |
|
breakdown.
As it is important to develop a noncontact method for detecting the
insulation |
|
fault,
this paper proposes a new method to detect the wide-band electromagnetic
(E-M) |
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wave
emitted from PD using the Wavelet transform. The Wavelet transform
provides a |
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direct
quantitative measure of spectral content, "dynamic spectrum", in
the time-frequency |
|
domain.
This paper experimentally shows the "dynamic spectrum" of the
wide-band E-M |
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wave
emitted from PD in the time-frequency domain. This method is shown to be
useful |
|
for
detecting the symptom of the insulation breakdown occurring in GIS.
|
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Robust
partial discharge measurement in MV cable networks using discrete |
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Shim,
I.; Soragan, J.J.; Siew, W.H.; Sludden, K.; Gale, P.F. |
|
Power
Engineering Society Winter Meeting, 2000. IEEE , Volume: 1 , 2000 |
|
This
paper describes the application of discrete wavelet transforms to partial
discharge |
|
(PD)
measurements. Real field data measured from an 11 kV cable online has been
used |
|
to
test the algorithm. When taking measurements online, inaccuracy occurs
when the |
|
measurements
are affected by internal low frequency disturbances. Results demonstrate |
|
that
the use of this technique leads to accurate location of partial discharge.
|
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Analysis
of VHF-wideband electromagnetic noises from partial discharge using |
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discrete
wavelet transform |
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Tungkanawanich,
A.; Hamid, E.Y.; Kawasaki, Z.-I.; Matsuura, K. |
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Power
Engineering Society Winter Meeting, 2001 IEEE , Volume: 1 , 2001 |
|
In
this paper, a new application of discrete wavelet transform to analyze the
wide-band |
|
electromagnetic
waves from partial discharge (PD) is introduced. The discrete wavelet |
|
transform
has a special feature to perform the signal decomposition and
reconstruction by |
|
multi-resolution
analysis. Using this method, we can decompose the detected signal into |
|
various
frequency subband signals, and then estimate the true shape of PD signal
by |
|
mixing
the appropriately-selected decomposed signals. The threshold processing of |
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sub-band
signals is applied to reduce the interference of broadcasting signals. It
is shown |
|
that
the pro-posed method is advantageous to obtain almost the true shape of PD
signal, |
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whose
characteristics can be used for the purpose of PD classification.
Experimental |
|
results
obtained by applying high voltage on faulty insulators are used to show
the |
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effectiveness
of the proposed method. |
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