|
Electric
power quality disturbance detection using wavelet transform analysis |
|
Santoso,
S.; Powers, E.J.; Grady, W.M. |
|
Time-Frequency
and Time-Scale Analysis, 1994., Proceedings of the IEEE-SP |
|
International
Symposium on , 1994 |
|
The
objective of the paper is to present a novel approach to detect and
localize various |
|
electric
power quality disturbances using wavelet transform analysis. Unlike other |
|
approaches
where the detection is performed directly in the time domain, detection
using |
|
wavelet
transform analysis approach is carried out in the time-scale domain. As
far as |
|
detection
in power quality disturbance is concerned, one- or two-scale signal |
|
decomposition
is adequate to discriminate disturbances from their background. This |
|
approach
is robust in detecting and localizing a wide range of power disturbances
such as |
|
fast
voltage fluctuations, short and long duration voltage variations, and
harmonic |
|
Analysing
time-varying power system harmonics using wavelet transform |
|
Driesen,
J.; Van Craenenbroeck, T.; Reekmans, R.; Van Dommelen, D. |
|
Instrumentation
and Measurement Technology Conference, 1996. IMTC-96. Conference |
|
Proceeedings.IEEE
, Volume: 1 , 1996 |
|
This
paper presents the possibilities offered by the dyadic-orthonormal wavelet
transform |
|
used
in the multiresolution analysis of voltage- and current-signals. This
transform proves |
|
to
have some advantages over the classical FFT-based algorithms, when used in
electric |
|
power
quality assessment and the analysis of waveforms. Practical examples using |
|
waveforms
generated by energy saving lighting equipment, remote-control signals and
an |
|
adjustable
speed drive, are presented.
|
|
Application
of wavelets to model short-term power system disturbances |
|
Pillay,
P.; Bhattacharjee, A. |
|
Power
Systems, IEEE Transactions on , Volume: 11 Issue: 4 , Nov. 1996 |
|
This
paper presents an advanced mathematical tool for the analysis of power
system |
|
disturbances.
Disturbances that are nonperiodic require a more powerful mathematical |
|
technique
than the Fourier series. The "wavelet transformation" is one
such tool that can |
|
be
used. The wavelet transform translates the time-domain function into a
representation |
|
localized
not only in frequency but also in time. In this paper, the theory is
applied to |
|
model
several short term events like a capacitor switching transient, an
autoreclosure, and |
|
Power
quality assessment via wavelet transform analysis |
|
Santoso,
S.; Powers, E.J.; Grady, W.M.; Hofmann, P. |
|
Power
Delivery, IEEE Transactions on , Volume: 11 Issue: 2 , April 1996 |
|
In
this paper we present a new approach to detect, localize, and investigate
the feasibility |
|
of
classifying various types of power quality disturbances. The approach is
based on |
|
wavelet
transform analysis, particularly the dyadic-orthonormal wavelet transform.
The |
|
key
idea underlying the approach is to decompose a given disturbance signal
into other |
|
signals
which represent a smoothed version and a detailed version of the original
signal. |
|
The
decomposition is performed using multiresolution signal decomposition
techniques. |
|
We
demonstrate and test our proposed technique to detect and localize
disturbances with |
|
actual
power line disturbances. In order to enhance the detection outcomes, we
utilize the |
|
squared
wavelet transform coefficients of the analyzed power line signal. Based on
the |
|
results
of the detection and localization, we carry out an initial investigation
of the ability to |
|
uniquely
characterize various types of power quality disturbances. This
investigation is |
|
based
on characterizing the uniqueness of the squared wavelet transform
coefficients for |
|
each
power quality disturbance.
|
|
Feature
vector extraction for the automatic classification of power quality |
|
Lee,
C.H.; Lee, J.S.; Kim, J.O.; Nam, S.W. |
|
Circuits
and Systems, 1997. ISCAS '97., Proceedings of 1997 IEEE International |
|
Symposium
on , Volume: 4 , 1997 |
|
Page(s):
2681 -2684 vol.4 |
|
The
objective of this paper is to present a systematic approach to feature
vector |
|
extraction
for the automatic classification of power quality (PQ) disturbances, where |
|
discrete
wavelet transform (DWT), signal power estimation and data compression |
|
methods
are utilized to improve the classification performance and reduce
computational |
|
complexity.
To demonstrate the performance and applicability of the proposed method, |
|
some
test results obtained by analyzing 7-class power quality disturbances,
generated by |
|
the
EMTP, with white Gaussian noise are also provided.
|
|
Power
quality disturbance data compression using wavelet transform methods |
|
Santoso,
S.; Powers, E.J.; Grady, W.M. |
|
Power
Delivery, IEEE Transactions on , Volume: 12 Issue: 3 , July 1997 |
|
In
this paper we present a wavelet compression technique for power quality
disturbance |
|
data.
The compression technique is performed through signal decomposition,
thresholding |
|
of
wavelet transform coefficient and signal reconstruction. Threshold values
are |
|
determined
by weighing the maximun value at ech scale. Wavelet transform coefficients |
|
whose
values are below the threshold are discarded, while those that areare
above the |
|
threshold
are kept along with temporal locations. Whe show the efficacy of the
technique |
|
by
compressing actual disturbance data. The file size of the compressed data
is only |
|
one-sixth
to one-third thathat of the original data. Therefore, the cost related to
storing |
|
and
transmitting the data is significantly reduced.
|
|
A
measurement method based on the wavelet transform for power quality |
|
Angrisani,
L.; Daponte, P.; D'Apuzzo, M.; Testa, A. |
|
Power
Delivery, IEEE Transactions on , Volume: 13 Issue: 4 , Oct. 1998 |
|
The
paper presents a measurement method for power quality analysis in
electrical power |
|
systems.
The method is the evolution of an iterative procedure already set up by
the |
|
authors
and allows the most relevant disturbances in electrical power systems to
be |
|
detected,
localized and estimated automatically. The detection of the disturbance
and its |
|
duration
are attained by a proper application, on the sampled signal, of the
continuous |
|
wavelet
transform (CWT). Disturbance amplitude is estimated by decomposing, in an |
|
optimized
way, the signal in frequency subbands by means of the discrete time
wavelet |
|
transform
(DTWT). The proposed method is characterized by high rejection to noise, |
|
introduced
by both measurement chain and system under test, and it is designed for an |
|
agile
disturbance classification. Moreover, it is also conceived for future
implementation |
|
both
in a real-time measurement equipment and in an off-line analysis tool. In
the paper |
|
firstly
the theoretical background is reported and briefly discussed. Then, the
proposed |
|
method
is described in detail. Finally, some case-studies are examined in order
to highlight |
|
the
performance of the method.
|
|
A
New Criterion Based on the Wavelet Transform for Power Quality Studies and |
|
Waveform
Feature Localization |
|
Alexander
Domijan, Jr., Ph.D.; Muhammad Shaiq |
|
The
characteristics of power system transients seen today present a problem
for the |
|
classical
Fourier analysis technique because it fails to effectively and accurately
localize |
|
and
quantify power system effects. This paper looks into the application of
the technique |
|
of
multi-resolution analysis, based on the wavelet transforms, on voltage
waveforms |
|
obtained
from a pulse width modulation (PWM) induction motor drive during work on |
|
ASHRAE
Research Project 770. The technique is introduced and applied to |
|
mathematically
generated waveforms simulating the constant and transient speed |
|
operations
of a PWM induction motor. It is then applied to waveforms obtained during |
|
constant
speed operation of an actual induction motor. |
|
A new
power quality criterion based on the wavelet transform coefficients also
is |
|
presented
and compared to total harmonic distortion (THD). It is seen that since THD
is |
|
based
only on the root mean squared (RMS) value of the harmonics present in the |
|
waveforms,
it fails to quantify the effects of phases of these harmonics. In addition,
all |
|
harmonics
are weighted equally when calculating the THD, which leads to loss of |
|
information
regarding the individual harmonic number and magnitude. The new method |
|
presents
a number that takes into account all the above mentioned effects.
|
|
A
study on the application of wavelet analysis to power quality |
|
Kopparapu,
C.; Chandrasekaran, A. |
|
System
Theory, 1998. Proceedings of the Thietieth Southeastern Symposium on ,
1998 |
|
The
quality of electric power is a major concern, since poor electric power
quality results |
|
in
malfunctions, instabilities and shorter lifetime of the load. The poor
quality of electric |
|
power
can be attributed to power line disturbances such as waveshape faults, |
|
overvoltages,
capacitor switching transients, harmonic distortion and impulse transients. |
|
For
diagnosing power quality problems, the causes of the disturbances should
be |
|
understood
before appropriate actions can be taken. Monitoring the voltages and
currents |
|
is the
first requirement in this process. In order to determine the causes, one
should be |
|
able
to classify the type of disturbances from the monitored data. Several
approaches |
|
such
as point-to-point comparison of adjacent systems, neural networks and
expert |
|
systems
have been proposed and implemented in the past. Wavelet analysis is
gaining |
|
greater
importance for the recognition of disturbances. A study about the
performance of |
|
wavelets
in detecting and classifying the power quality disturbances is reported in
this |
|
Advanced
techniques for power quality analysis: a real case study |
|
Poisson,
O.; Rioual, P.; Assef, Y.; Bastard, P. |
|
Harmonics
and Quality of Power Proceedings, 1998. Proceedings. 8th International |
|
Conference
On , Volume: 1 , 1998 |
|
This
paper presents a real case study relating to power quality. An industrial
customer |
|
power
system is investigated in order to analyze misoperation linked with the
switching of |
|
harmonic
compensation filters. First, overvoltage transients are recorded on the
main set |
|
of
busbar. Then, the whole power system and the switching of the harmonic
filters are |
|
simulated
with EMTP. Results are compared with real records. Furthermore, the
wavelet |
|
theory
is used for the analysis of currents and voltages during switching. A
comparison |
|
between
simulations and measurements shows the accuracy of the method presented in |
|
the
analysis of transient events. Finally, an analytical study of the
switching transient has |
|
confirmed
results about the main frequencies measured. The whole method (EMTP |
|
simulation
and wavelet analysis) is a useful way to investigate industrial customers'
power |
|
systems
from a power quality point of view.
|
|
Application
of wavelets to classify power system disturbances |
|
Shyh-Jier
Huang, Cheng-Tao Hsieh and Ching-Lien Huang |
|
Electric
Power Systems Research, Volume 47, Issue 2, 15 October 1998, Pages 87-93 |
|
The
wavelet transform approach is proposed in this paper to classify various
power |
|
system
disturbances. On encountering various disturbances, the proposed method is
useful |
|
to
categorize these shortfalls into different groups so that operators can
decide on |
|
strategies
to suppress or eliminate them effectively. Different from those Fourier-based |
|
transforms,
the wavelet transform approach is more efficient in tracking signal
dynamics |
|
as
time varies. The method has been tested through the classification of
various simulated |
|
disturbances,
including voltage sag, voltage swell, momentary interruption, oscillatory |
|
transients
and flat-tops. Testing results showed the feasibility and practicality of
the |
|
method
for the applications.
|
|
Data
reduction of power quality disturbances a wavelet transform approach |
|
Cheng-Tao
Hsieh, Shyh-Jier Huang and Ching-Lien Huang |
|
Electric
Power Systems Research, Volume 47, Issue 2, 15 October 1998, Pages 79-86 |
|
In
this paper, application of a wavelet transform approach for the data
reduction of power |
|
quality
disturbances is proposed. In this approach, we extracted the difference
signals |
|
between
the original signal and the reference waveform by a subtractor. These
extracted |
|
signals
were then compressed through wavelet transform methods. In this way, the |
|
amount
of data was shown significantly reduced. The data transmission and storage |
|
capability
can be also enhanced. We have investigated towards the reduction of
various |
|
power
quality disturbance data by the proposed method. Test results demonstrated
the |
|
effectiveness
of the method for the applications.
|
|
Daubechies
wavelets in quality of electrical power |
|
Brito,
N.S.D.; Souza, B.A.; Pires, F.A.C. |
|
Harmonics
and Quality of Power Proceedings, 1998. Proceedings. 8th International |
|
Conference
On , Volume: 1 , 1998 |
|
Wavelet
analysis is a new method for electrical power quality analysis. A brief
theoretical |
|
background
on the wavelet theory and suggestions of some applications in the area of |
|
power
quality are presented. Investigations on the use of some Daubechies
wavelets, |
|
namely
Daub4, Daub12 and Daub20, are carried out.
|
|
Fourier
transform, wavelets, Prony analysis: tools for harmonics and quality of |
|
Harmonics
and Quality of Power Proceedings, 1998. Proceedings. 8th International |
|
Conference
On , Volume: 1 , 1998 |
|
The
Fourier transform is a very useful tool for signal studies. Nevertheless
there are |
|
many
problems in using it; but these problems are very well known and correctly |
|
explained
in literature. Wavelets are not usual in power network analysis. However,
they |
|
are
easy to use and give good results; the edge effects are transient and the
computation |
|
time
may be reasonable. Prony analysis is only found in a few papers about
power |
|
networks.
There are few high-performance decomposition programs. The best ones |
|
remain
sensitive to noise. They require a long observation time with many samples.
But, |
|
when
the analysis succeed, this method is the most powerful to explain what
happens in a |
|
power
network transient. This paper explains as simply as possible the wavelet
and the |
|
Prony
analyses and shows, qualitatively, their performances and their limits.
|
|
Power
quality disturbance detection and classification using wavelets and |
|
artificial
neural networks |
|
Perunicic,
B.; Mallini, M.; Wang, Z.; Liu, Y. |
|
Harmonics
and Quality of Power Proceedings, 1998. Proceedings. 8th International |
|
Conference
On , Volume: 1 , 1998 |
|
This
article develops a method to detect and classify power quality problems
using a novel |
|
combination
of digital filtering, wavelets and artificial neural networks. The method
is |
|
developed
for voltage waveforms of arbitrary sampling rate and number of cycles,
using a |
|
large
variety of power quality events simulated with MATLAB(R) software, in
addition |
|
to
sampled waveforms from utility monitoring and EMTP(R) simulations. Power
system |
|
monitoring,
augmented by the ability to automatically characterize disturbed signals,
is a |
|
powerful
tool for the power system engineer to use in addressing power quality
issues. |
|
This
is a step toward the goal of automating the real-time monitoring,
detection and |
|
classification
of power signals.
|
|
Short
time Fourier transforms and other transforms applied to the calibration of |
|
Precision
Electromagnetic Measurements Digest, 1998 Conference on , 1998 |
|
This
paper is concerned with the measurement of nonsinusoidal waveforms, in
particular |
|
the
use of waveform transforms in the calibration of power analyser
instruments designed |
|
to
make harmonic measurements to the requirements of the IEC standards on
harmonics. |
|
The
consequences of harmonics to electricity supply companies and users are |
|
considered.
The paper then reviews the IEC standards regarding steady-state harmonics |
|
and
fluctuating harmonics.
|
|
The
application of wavelet theory in analysis and compensation of harmonics in |
|
Energy
Management and Power Delivery, 1998. Proceedings of EMPD '98. 1998 |
|
International
Conference on , Volume: 1 , 1998 |
|
A
novel approach to visualise singular signals in faulted power systems is
proposed. The |
|
wavelet
transformation technique is applied to help monitor singular signals in
the time |
|
dimension.
Using the proposed scheme, singular signals in faulted power systems can
be |
|
closely
observed. The proposed method has been tested for the inspection of
singular |
|
signals
in faulted DC power systems and of the arc signals in grounding faults.
The results |
|
demonstrate
the merits of the proposed method for application.
|
|
Time-varying
transient harmonics measurement based on wavelet transform |
|
Wang
Jianze; Ran Qiwen; Wang Fei; Ji Yanchao |
|
Power
System Technology, 1998. Proceedings. POWERCON '98. 1998 International |
|
Conference
on , Volume: 2 , 1998 |
|
Page(s):
1556 -1559 vol.2 |
|
This
paper presents a new time-varying harmonics measurement scheme based on
the |
|
wavelet
transform. By projecting the amplitude of harmonics onto the subspace
spanned |
|
by the
wavelet and scaling functions, the proposed method transforms the time-varying |
|
amplitude
estimation into constant coefficient estimation and achieves the time-varying |
|
harmonics
measurement using the least mean squares algorithm (LMS). Meanwhile, the |
|
recursive
algorithm (RLS) realizes the online tracking for harmonics.
|
|
Wavelet
representation of voltage flicker |
|
Tongxin
Zheng and Elham B. Makram |
|
Electric
Power Systems Research, Volume 48, Issue 2, 15 December 1998, Pages |
|
Voltage
flicker can be considered as a voltage magnitude modulated signal with a |
|
frequency
ranging from 0.5 to 30 Hz. Wavelet transform is a powerful tool to analyze
this |
|
kind
of nonstationary, wide-range frequency signal. The wavelet representation
of |
|
voltage
flicker signal is presented in this paper. The proposed scheme is
implemented in |
|
three
steps. Firstly, a low-pass demodulation filter is designed to find the
magnitude of 60 |
|
Hz
component. Accordingly, a high degree of accuracy may be achieved and the
effect |
|
of the
transient, harmonics and white noise may be eliminated. Secondly, a
multiresolution |
|
analysis
(MRA) scheme that is an orthonormal wavelet transform, can then be applied
to |
|
decompose
the demodulated signal into several components according to the scales. |
|
Components
at high scale can be considered as white noise, while components at the
low |
|
scale
represent the voltage fluctuation. The smooth version left by the MRA
scheme |
|
represents
the DC component. Finally, the voltage flicker level can be estimated by
the |
|
wavelet
coefficients at different scales, which give the time and frequency
information. |
|
Numerical
examples are also presented in this paper to show the efficiency of the |
|
A
fuzzy Petri-net expert system for power quality classification using
wavelet |
|
Hong-Tzer
Yang; Chiung-Chou Liao; Jian-Fu Chen; Wen-Yeau Chang |
|
Electric
Power Engineering, 1999. PowerTech Budapest 99. International Conference
on |
|
This
paper proposes a fuzzy Petri-net (FPNs) expert system for classification
of the |
|
power
quality (PQ) problems. Based on the wavelet transform, the proposed expert |
|
system
detects and localizes in time the transients of the signals due to various
fault |
|
events.
By calculating related indices to the PQ, the FPNs inference-module draws |
|
possible
causes of the disturbances as well as its credibility values from its
knowledge |
|
base.
Attributed to the FPNs structure, the knowledge expression and inference
process |
|
can be
achieved systematically and graphically. To verify the performance of the |
|
proposed
FPNs expert system, a wide variety of disturbance signals simulated by |
|
Electromagnetic
Transients Program (EMTP) package were employed. The development |
|
and
the effectiveness of the proposed system as well as the testing results
are presented |
|
A
noise suppression method for improvement of power quality using wavelet |
|
Kim,
C.H.; Park, S.W.; Aggarwal, R.K.; Johns, A.T. |
|
Power
Engineering Society Summer Meeting, 1999. IEEE , Volume: 1 , 1999 |
|
Electric
power quality has become an important issue in power systems. This is due
to the |
|
fact
that the usage of power electronic equipment and electronic-based loads,
which are |
|
sensitive
to power quality disturbances, has increased, and thus normal operations
in |
|
industrial
and commercial environments are becoming more vulnerable to the electric |
|
power
quality disturbances. In order to improve the quality of power, this paper
presents a |
|
new
noise suppression method to remove the noise associated with various types
of |
|
electric
power disturbances using the discrete wavelet transform. Power system |
|
disturbances
such as those due to voltage sag, voltage swell, outage, waveshape |
|
fault-impulse,
harmonic distortion, capacitor energisation transients and arc furnace are |
|
simulated
using the well known Electromagnetic Transients Program (EMTP). The |
|
wavelet
transform, which has received considerable interest in many other areas
such as |
|
acoustics,
communications, etc., is proposed as a fast and effective means of
analysing |
|
voltage
and current waveforms generated during power system disturbances; this
method |
|
hinges
upon realising a given noise-ridden signal into a number of other signals
which |
|
represent
detailed components of the original signal. The decomposition is performed |
|
using
multi-resolution signal decomposition techniques. The simulation results
clearly |
|
demonstrate
the superiority and effectiveness of the wavelet transform in both voltage |
|
and
current signal noise reduction.
|
|
A
wavelet based power quality monitoring system considering noise effects |
|
Hong-Tzer
Yang; Chiung-Chou Liao; Pai-Chuan Yang; Kun-Yuan Huang |
|
Electric
Power Engineering, 1999. PowerTech Budapest 99. International Conference
on |
|
Based
on the discrete wavelet transform (DWT), a power quality (PQ) monitoring
system |
|
could
easily and correctly detect and localize the disturbances in power systems. |
|
However,
once the signal under investigation is corrupted by noise, the performance
of |
|
the
DWT on detecting the disturbance would greatly degrade, due to the
difficulty in |
|
giving
appropriate thresholds to eliminate the noises. To enhance the capability
of the |
|
wavelet-based
PQ monitoring system, this paper proposes a denoising approach for the |
|
detection
of transient disturbance events in noisy environment. In the proposed
denoising |
|
approach,
the thresholds to eliminate the noises are adaptively determined according
to |
|
the
background noises. The abilities of the DWT in detecting and localizing
the |
|
disturbances
can hence be restored.
|
|
Application
of Morlet wavelets to supervise power system disturbances |
|
Shyh-Jier
Huang; Cheng-Tao Hsieh; Ching-Lien Huang |
|
Power
Delivery, IEEE Transactions on , Volume: 14 Issue: 1 , Jan. 1999 |
|
A
wavelet transform approach using a Morlet basis function is proposed to
supervise |
|
power
system disturbances in this paper. With the time-frequency localization |
|
characteristics
embedded in wavelets, the time and frequency information of a waveform |
|
can be
presented as a visualized scheme. Different from the fast Fourier
transform, the |
|
wavelet
transform approach is more efficient in monitoring various disturbances as
time |
|
varies.
The method has been tested on the detection of various simulated
disturbances |
|
including
voltage sag, voltage swell, momentary interruption and oscillatory
transients and |
|
on the
harmonic analysis of the arc furnace from the field test data. Testing
results |
|
demonstrated
the practicality and advantages of the proposed method for the
applications.
|
|
New
robust voltage sag disturbance detector using an adaptive prediction error |
|
Chung,
J.; Powers, E.J.; Grady, W.M.; Bhatt, S.C. |
|
Power
Engineering Society Summer Meeting, 1999. IEEE , Volume: 1 , 1999 |
|
This
paper presents a robust power disturbance detection algorithm. The power
line |
|
disturbance
is extracted from the steady-state 60 Hz and harmonics background using an |
|
adaptive
prediction error filter. In order to detect the disturbance, a stop-and-go
CA |
|
CFAR
detector algorithm is utilized. The algorithm is demonstrated via
simulations, and |
|
actual
power transmission line data are utilized to demonstrate its performance
and to |
|
compare
the performance to wavelet-based detectors.
|
|
New
signal processing tools applied to power quality analysis |
|
Poisson,
O.; Rioual, P.; Meunier, M. |
|
Power
Delivery, IEEE Transactions on , Volume: 14 Issue: 2 , April 1999 |
|
This
paper deals with the comparison of new signal processing tools for power
quality |
|
analysis.
Three new signal processing techniques are considered: the continuous
wavelet |
|
transform,
the multiresolution analysis and the quadratic transform. Their
theoretical |
|
behaviours
are investigated using the basic theory of the Fourier transform. Then, |
|
examples
of the four most frequent disturbances met in the power system are chosen. |
|
Finally,
each kind of electrical disturbance is analyzed with example representing
each |
|
tool.
A qualitative comparison of results shows the advantages and drawbacks of
each |
|
new
signal processing technique applied to voltage disturbance analysis. The
continuous |
|
wavelet
transform appears to be a reliable method for detecting and measuring
voltage |
|
sags,
flicker and transients in power quality analysis.
|
|
Power
quality detection and classification using wavelet-multiresolution signal |
|
Gaouda,
A.M.; Salama, M.M.A.; Sultan, M.R.; Chikhani, A.Y. |
|
Power
Delivery, IEEE Transactions on , Volume: 14 Issue: 4 , Oct. 1999 |
|
The
wavelet transform is introduced as a powerful tool for monitoring power
quality |
|
problems
generated due to the dynamic performance of industrial plants. The paper |
|
presents
a multiresolution signal decomposition technique as an efficient method in |
|
analyzing
transient events. The multiresolution signal decomposition has the ability
to |
|
detect
and localize transient events and furthermore classify different power
quality |
|
disturbances.
It can also be used to distinguish among similar disturbances.
|
|
Power
system transient and harmonic studies using wavelet transform |
|
Tongxin
Zheng; Makram, E.B.; Girgis, A.A. |
|
Power
Delivery, IEEE Transactions on , Volume: 14 Issue: 4 , Oct. 1999 |
|
This
paper presents the application of wavelet transforms in power system
transient and |
|
harmonic
analyses. Based on the discrete time domain approximation, the system |
|
components
such as resistors, inductors and capacitor are modeled respectively in the |
|
discrete
wavelet domain for the purpose of transient and steady state analyses.
Since the |
|
power
system is described by a set of ordinary differential equations, an
initial value of the |
|
state
variable is considered for the transient analysis, while a periodic
condition is applied |
|
to the
state variable for the steady state analysis. The wavelet domain impedance
is set |
|
up,
and the equivalent circuit is thus built for system simulation. This
method can be |
|
implemented
by any kind of orthogonal wavelet transform. Numerical results from an arc |
|
furnace
system are also presented for the transient, harmonic and time-frequency |
|
Short-time
Fourier transforms and Wigner-Ville distributions applied to the |
|
calibration
of power frequency harmonic analyzers |
|
Instrumentation
and Measurement, IEEE Transactions on , Volume: 48 Issue: 2 , April |
|
This
paper is concerned with the measurement of nonsinusoidal waveforms, in
particular |
|
the
use of waveform transforms in the calibration of power frequency harmonic
analyzer |
|
instruments
designed to make harmonic measurements under nonstationary conditions. |
|
The
suitability of the Fourier transform (FT) for the analysis of
nonstationary waveforms |
|
is
discussed. A method involving windowing of the waveform data known as the |
|
short-time
Fourier transform (STFT) and its application to harmonic amplitude |
|
measurements
is considered. Limitations in time and frequency resolution inherent in
the |
|
STFT
lead to the development and investigation of the Wigner-Ville Distribution
for use in |
|
this
application. The performance of the various transforms are compared by
simulation. |
|
Results
using a test signal, typical of a practical signal encountered by harmonic
analyzers, |
|
are
presented for each transform.
|
|
Wavelet
analysis. An application in power quality |
|
Dias,
G.A.D.; Tamagna, A. |
|
Electric
Power Engineering, 1999. PowerTech Budapest 99. International Conference
on |
|
This
paper presents some studies about the application of the wavelet transform
(WT) in |
|
typical
waveforms related with power quality (PQ). Several mother wavelets were
used |
|
in
signal treatment and results are partially shown in the paper. The authors
show what |
|
can be
done with the WT in signal process analysis.
|
|
Wavelets
for the analysis and compression of power system disturbances |
|
Littler,
T.B.; Morrow, D.J. |
|
Power
Delivery, IEEE Transactions on , Volume: 14 Issue: 2 , April 1999 |
|
Wavelets
introduce new classes of basis functions for time-frequency signal
analysis and |
|
have
properties particularly suited to the transient components and
discontinuities evident |
|
in
power system disturbances. Wavelet analysis involves representing signals
in terms of |
|
simpler,
fixed building blocks at different scales and positions. This paper
examines the |
|
analysis
and subsequent compression properties of the discrete wavelet and wavelet |
|
packet
transforms and evaluates both transforms using an actual power system |
|
disturbance
from a digital fault recorder. The paper presents comparative compression |
|
results
using the wavelet and discrete cosine transforms and examines the
application of |
|
wavelet
compression in power monitoring to mitigate against data communications |
|
Wavelet-transform-based
algorithm for harmonic analysis of power system |
|
Generation,
Transmission and Distribution, IEE Proceedings- , Volume: 146 Issue: 3 ,
May |
|
The
paper develops an approach, based on the wavelet transform, for the
evaluation of |
|
harmonic
contents of power system waveforms. The new algorithm can simultaneously |
|
identify
all harmonics including integer, noninteger and subharmonics. In the first
step of |
|
the
approach, the frequency spectrum of the waveform is decomposed into
subbands |
|
using
discrete wavelet packet transform filter banks. In the second step, a
continuous |
|
wavelet
transform is applied to nonzero subbands to evaluate the harmonic contents.
In |
|
the
first step, there is the problem of images due to down samplings and up
samplings of |
|
the
waveform. A method for alleviating this image problem is developed in the
paper. |
|
Methods
are developed to accurately quantify harmonics frequency amplitude and
phase. |
|
The
approach is validated by its application to synthesised waveforms and to
power |
|
system
waveforms measured in the Western Australia system. It is found to be
powerful |
|
and
suitable for practical use.
|
|
A
case study of transformer saturation in distribution systems |
|
Dias,
G.A.D.; Tamagna, A. |
|
Harmonics
and Quality of Power, 2000. Proceedings. Ninth International Conference on
, |
|
The
aim of this paper is to indicate the adopted solutions to solve the
problem of power |
|
quality
due the 60 Hz power transformers saturation installed in the Brazilian
power |
|
distribution
system of Chui and Santa Vitoria do Palmar cities that operates at 50 Hz.
|
|
A
correlation-based noise suppression algorithm for power quality monitoring |
|
through
wavelet transform |
|
Hong-Tzer
Yang; Chiung-Chou Liao |
|
Power
System Technology, 2000. Proceedings. PowerCon 2000. International |
|
Conference
on , Volume: 3 , 2000 |
|
Page(s):
1311 -1316 vol.3 |
|
The
wavelet transform (WT) technique has been proposed for detecting and
localizing |
|
transient
disturbance in the power systems. The disturbance is detected by comparing
the |
|
transformed
signal with an empirically-given threshold. However, as the signal under |
|
analysis
contains noises, especially the white noise with flat spectrum, the
threshold is |
|
difficult
to give. Due to the nature of flat spectrum, a filter cannot just get rid
of the noise |
|
without
removing the significant disturbance signals together. To enhance the WT |
|
technique
in processing the noise-riding signals, this paper proposes a noise-suppression |
|
algorithm.
The abilities of the WT in detecting and localizing the disturbances can
hence |
|
be
restored. Finally, this paper employed the actual data obtained from the
practical |
|
power
systems of Taiwan Power Company (TPC) to test the effectiveness of the |
|
developed
de-noising scheme.
|
|
A
new method for power systems frequency tracking based on trapezoid wavelet |
|
Ren
Zhen; Huang Qungu; Guan Lin; Huang Wenying |
|
Advances
in Power System Control, Operation and Management, 2000. APSCOM-00. |
|
2000
International Conference on , Volume: 2 , 2000 |
|
In
this paper, a trapezoid complex wavelet function and associate trapezoid
wavelet |
|
transform
is presented. This complex wavelet function is possessed of better
localizability |
|
and
symmetry and so by means of trapezoid wavelet transform, amplitude and
phase |
|
information
in signal to be processed. By comparison with other wavelet functions, |
|
trapezoid
complex wavelet function has even frequency characteristic. Moreover, by |
|
using
trapezoid complex wavelet transform in this paper, frequencies of signals
in power |
|
systems
and in loss of field in generator are tracked. Obviously it is shown
trapezoid |
|
complex
wavelet transform is an effective method of making frequency tracing in
power |
|
systems
and is of important sociala and economic fruit.
|
|
Analysing
power system waveforms using wavelet-transform approach |
|
Kit Po
Wong; Van Long Pham |
|
Advances
in Power System Control, Operation and Management, 2000. APSCOM-00. |
|
2000
International Conference on , Volume: 2 , 2000 |
|
This
paper presents the application of wavelet transform-based algorithm to the
harmonic |
|
analysis
of non-stationary power system waveforms. The waveforms are first |
|
decomposed
into-sub-bands of smaller frecuency spectra using modified discrete
wavelet |
|
packet
transform filter banks. Harmonics trends are obtained from the decomposed |
|
outputs.
Continuos wavelet transform is then applied to sections of the decomposed |
|
sub-bands
to evaluate the harmonic frequencies, amplitudes and phases. The results
of |
|
analysis
of the fiefield-test capacitor bank switching waveforms show that the
approach is |
|
excellent
for harmimonic analysis of non-stationary power system waveform. It gives |
|
both
the harmonict rends and the harmonic anamplitude, phase and frequency
values.
|
|
Application
of continuous wavelet transform for study of voltage |
|
flicker-generated
signals |
|
Shyh-Jier
Huang; Cheng-Tao Hsieh |
|
Aerospace
and Electronic Systems, IEEE Transactions on , Volume: 36 Issue: 3 Part: 1
, |
|
An
application of continuous wavelet transform (CWT) for the analysis of
voltage |
|
flicker-generated
signals is proposed. With the time-frequency localization characteristics |
|
embedded
in wavelets, the time and frequency information of a waveform can be |
|
integrally
presented, thereby enhancing the monitoring of voltage flicker-generated
signals |
|
at
different time intervals. The Morlet wavelet has been selected as the
basis function for |
|
the
CWT in the proposed method. The merit of the method lies in that the
signal |
|
component
at any frequency of interest can be more easily monitored than by discrete |
|
wavelet
transform (DWT). The high frequency required in the voltage flicker study
can |
|
be
also comfortably accomplished. This approach has been applied to
investigate various |
|
simulated
voltage flicker-generated signals, and inspect the data recorded from the
actual |
|
are
furnace operation. Test results help solidify the practicality and
advantages of the |
|
proposed
method for the applications.
|
|
Characterization
of distribution power quality events with Fourier and wavelet |
|
Santoso,
S.; Grady, W.M.; Powers, E.J.; Lamoree, J.; Bhatt, S.C. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 1 , Jan. 2000 |
|
It is
the objective of this paper to present unique features that characterize
power quality |
|
events
and methodologies to extract them from recorded voltage and/or current |
|
waveforms
using Fourier and wavelet transforms. Examples of unique features include |
|
peak
amplitudes, RMS, frequency, and statistics of wavelet transform
coefficients. These |
|
features
are derived from well documented theories, power engineers' heuristics
gained |
|
through
long years of experience, and power quality data collected in recent years. |
|
Converter
operation, transformer energization, and capacitor energization (which
includes |
|
normal,
back-to-back, and re-strike on opening energization), representing three
common |
|
power
quality events at the distribution level, are presented. These examples
provide the |
|
basis
for further characterization of other power quality events.
|
|
Computation
of continuous wavelet transform via a new wavelet function for |
|
visualization
of power system disturbances |
|
Shyh-Jier
Huang; Cheng-Tao Hsieh |
|
Power
Engineering Society Summer Meeting, 2000. IEEE , Volume: 2 , 2000 |
|
In
this paper, a computation of continuous wavelet transform via a new
wavelet function |
|
is
proposed for the visualization of electric power system disturbances. The
proposed |
|
wavelet
function is derived from the B-spline function. In the employment of the
method, |
|
the
ratio of the frequency bandwidth to the center frequency depends only on
the |
|
parameter
settings, which can be easily adjusted for different resolution needs.
Because |
|
this
new function is a piecewise polynomial, the wavelet transform can be less |
|
computation-intensive.
Besides, it is seen compactly supported, the integration process |
|
can be
thus faster along with a higher accuracy. In the paper, this proposed
wavelet |
|
function
is embedded into the wavelet transform scheme, and applied to investigate
the |
|
disturbances
recorded in a steel plant located at southern Taiwan. Computation results |
|
reveal
that the proposed approach can be a useful aid in the monitoring of power
system |
|
disturbances.
It is also suitable to extend this approach to other industry applications |
|
where
electric power quality is crucially required.
|
|
Detection
and measurement of power quality disturbances using wavelet |
|
Poisson,
O.; Rioual, P.; Meunier, M. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 3 , July 2000 |
|
This
paper deals with the use of a continuous wavelet transform to detect and
analyze |
|
voltage
sags and transients. A recursive algorithm is used and improved to compute
the |
|
time-frequency
plane of these electrical disturbances. Characteristics of investigated |
|
signals
are measured on a time-frequency plane. A comparison between measured |
|
characteristics
and benchmark values detects the presence of disturbances in analyzed |
|
signals
and characterizes the type of disturbances. Duration and magnitude of
voltage |
|
sags
are measured, transients are located in the width of the signal.
Furthermore, |
|
meaningful
time and frequency components of transients are measured. The whole |
|
method
is implemented and tested over a sample representing recorded disturbances. |
|
Detection
and measurement results are compared using classical methods.
|
|
Discussion
of "Characterization of distribution power quality events with
Fourier |
|
Funabashi,
T.; Santoso, S.; Grady, W.M.; Powers, E.J.; Lamoree, J.; Bhatt, S.C. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 4 , Oct. 2000 |
|
The
author discusses the original paper ("Characterization of
distribution power quality |
|
events
with Fourier and wavelet transforms", S. Santoso et al., see ibid.,
vol. 15, no. 1, p. |
|
247-54,
2000) and presents his observations. The original authors' response to the |
|
discussion is
also included.
|
|
Discussion
of "Power quality disturbance waveform recognition using |
|
wavelet-based
neural classifier-Part 1: theoretical foundation" |
|
Negnevitsky,
M.; Faybisovich, V.; Santoso, S.; Powers, E.J.; Grady, W.M.; Parsons, |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 4 , Oct. 2000 |
|
The
authors discuss the original paper ("Power quality disturbance
waveform recognition |
|
using
wavelet-based neural classifier-Part 1: theoretical foundation", S.
Santoso et al., see |
|
ibid.,
vol. 15, no. 1, p. 222-8, 2000) and present their observations. The
original authors' |
|
response
to the discussions are included.
|
|
Discussion
on "Power quality disturbance waveform recognition using |
|
wavelet-based
neural classifier. 2. Application" |
|
Negnevitsky,
M.; Faybisovich, V. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 4 , Oct. 2000 |
|
M.
Negnevitsky and V. Faybisovich comment separately on the paper by S.
Santoso et al. |
|
(see
ibid., vol.15, no.1, p.229-35, 2000). Negnevitsky asks questions regarding
the |
|
wavelet
based neural classifier. Faybisovich asks questions regarding the type of
wavelet |
|
chosen
and the learning scheme. The original authors reply to the comments.
|
|
Power
quality assessment and load identification |
|
Cano
Plata, E.A.; Tacca, H.E. |
|
Harmonics
and Quality of Power, 2000. Proceedings. Ninth International Conference on
, |
|
The
number and power of loads that pollute, from an electric point of view,
the electric |
|
network
are constantly increasing. For this reason, this study aims to define a
parameter |
|
to
assess, in terms of distortion and unbalance, the quality of an electric
network. Taking, |
|
as a
starting point, the advantages and limitations of wavelets methods
proposed in the |
|
literature,
a new index useful for quantifying the load characteristic, is introduced.
The |
|
efficiency
of this index has been verified by computer simulations to assess the
method |
|
applicability
to three-wire measurements of instantaneous power theory, in many
realistic |
|
Power
quality disturbance waveform recognition using waveleet-based neural |
|
classifie.
I. Theoretical foundation. |
|
Santoso,
S.; Powers, E.J.; Grady, W.M.; Parsons, A.C. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 1 , Jan. 2000 |
|
Existing
techniques for recognizing and identifying power quality disturbance
waveforms |
|
are
primarily based on visual inspection of the waveform. It is the purpose of
this paper to |
|
bring
to bear recent advances, especially in wavelet transforms, artificial
neural |
|
networks,
and the mathematical theory of evidence, to the problem of automatic power |
|
quality
disturbance waveform recognition. Unlike past attempts to automatically
identify |
|
disturbance
waveforms where the identification is performed in the time domain using
an |
|
individual
artificial neural network, the proposed recognition scheme is carried out
in the |
|
wavelet
domain using a set of multiple neural networks. The outcomes of the
networks |
|
are
then integrated using decision making schemes such as a simple |
|
voting
scheme or the Dempster–Shafer theory of evidence. With such a
configuration, the |
|
classifier
is capable of providing a degree of belief for the identified disturbance |
|
Power
quality disturbance waveform recognition using wavelet-based neural |
|
classifier.
II. Application |
|
Santoso,
S.; Powers, E.J.; Grady, W.M.; Parsons, A.C. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 1 , Jan. 2000 |
|
A
wavelet-based neural classifier is constructed and thoroughly tested under
various |
|
conditions,
The classifier is able to provide a degree of belief for the identified
waveform. |
|
The
degree of belief gives an indication about the goodness of the decision
made. It is |
|
also
equipped with an acceptance threshold so that it can reject ambiguous
disturbance |
|
waveforms.
The classifier is able to achieve the accuracy rate of more than 90% by |
|
rejecting
less than 10% of the waveforms as ambiguous.
|
|
Sub-harmonic
state estimation in power systems |
|
Van
Long Pham; Kit Po Wong; Watson, N.; Arrillaga, J. |
|
Power
Engineering Society Winter Meeting, 2000. IEEE , Volume: 2 , 2000 |
|
Page(s):
1168 -1173 vol.2 |
|
This
paper presents an approach for system-wide sub-harmonic estimation using
state |
|
estimation
(SE) algorithm together with the wavelet-transform (WT)-based algorithm. |
|
The WT-based
algorithm is used to identify sub-harmonics in the measured power system |
|
waveforms.
SE is then performed to estimate the sub-harmonic levels for the whole |
|
system
based on a few selected measurements. Symbolic observability analysis (OA) |
|
method
is applied to determine the system solvability for the SE algorithm from a
set of |
|
measurements.
Location and type of sub-harmonic sources are then determined from the |
|
estimated
results. The approach is illustrated using a real power system and real
field-test |
|
waveforms.
The results show the accuracy of the method and its potential for analysis
of |
|
Time-frequency
and time-scale domain analysis of voltage disturbances |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 4 , Oct. 2000 |
|
This
paper discusses the analysis of voltage disturbance recordings in the
time-frequency |
|
domain
and in the time-scale domain. The discrete short-time Fourier transform (STFT)
is |
|
used
for the time-frequency domain; dyadic and binary-tree wavelet filters for
the |
|
time-scale
domain. The theory is explained with special emphases on the analysis of |
|
voltage
disturbance data. Dyadic wavelet filters are not suitable for the harmonic
analysis |
|
of
disturbance data. Filter center frequencies and bandwidths are inflexible,
and the |
|
results
do not give easy insight in the time behavior of the harmonics. On the
other hand, |
|
band-pass
filter outputs from discrete STFT are well associated with harmonics and
are |
|
thus
more useful for power system analysis. With a properly chosen window size,
the |
|
discrete
STFT is also able to detect and analyze transients in a voltage
disturbance. |
|
Overall,
the STFT is more suitable than wavelet filters for the analysis of power
system |
|
voltage
disturbance data.
|
|
TRANSIENTMETER:
a distributed measurement system for power quality |
|
Daponte,
P.; Di Penta, M.; Mercurio, G. |
|
Harmonics
and Quality of Power, 2000. Proceedings. Ninth International Conference on
, |
|
Page(s):
1017 -1022 vol.3 |
|
The
paper deals with the design and implementation of TRANSIENTMETER, a |
|
monitoring
system for the detection, classification and measurement of disturbances
on |
|
electrical
power systems. TRANSIENTMETER uses a CORBA architecture as |
|
communication
interface, wavelet-based methods for automatic signal classification and |
|
characterization,
and a smart trigger circuit for the detection of disturbances.
|
|
Wavelet
based on-line disturbance detection for power quality applications |
|
Karimi,
M.; Mokhtari, H.; Iravani, M.R. |
|
Power
Delivery, IEEE Transactions on , Volume: 15 Issue: 4 , Oct. 2000 |
|
This
paper introduces a new online voltage disturbance detection approach based
on the |
|
wavelet
transform. The proposed approach: (1) identifies voltage disturbances; and
(2) |
|
discriminates
the type of event which has resulted in the voltage disturbance, e.g.
either a |
|
fault
or a capacitor-switching incident. The proposed approach is: (1)
significantly faster; |
|
and
(2) more precise in discriminating the type of transient event than
conventional |
|
voltage-based
disturbance detection approaches. The feasibility of the proposed |
|
disturbance
detection approach is demonstrated based on digital time-domain simulation
of |
|
a
power distribution system using the PSCAD/EMTDC software package.
|
|
Wavelet
feature vectors for neural network based harmonies load recognition |
|
Chan,
W.L.; So, A.T.P.; Lai, L.L. |
|
Advances
in Power System Control, Operation and Management, 2000. APSCOM-00. |
|
2000
International Conference on , Volume: 2 , 2000 |
|
Power
quality embraces problems caused by harmonis, over or under-voltages, or
supply |
|
discontinuities.
Harmonics are caused for all non-linear loads. In order to fully
understand |
|
the
problems, and effective means of identifying sources of power harmonics is |
|
important.
In this paper we make use of new developments in wavelet so that each type |
|
of
current waveform polluted with power harmonics can well be represented by
a |
|
normalised
energy vector consisting of five elements. Furthermore, a mixture of |
|
harmonics
load can also be represented byby a corresponding vector. This paper |
|
describes
the mathematics and algorithms for arriving at ththe vectors, forming a s
a |
|
strong
foundation for real-time harmonics signature recognition, in particular,
useful to the |
|
re-structuring
of the whole electric power industry. The system performs exceptionally |
|
well
with the aid of an artificial neural network.
|
|
Wavelet-based
algorithm for voltage flicker analysis |
|
Ming-Tang
Chen; Sakis Meliopoulos, A.P. |
|
Harmonics
and Quality of Power, 2000. Proceedings. Ninth International Conference on
, |
|
Fourier
transform-based algorithms have been popular for voltage flicker analysis; |
|
however,
their accuracy is unfavorably influenced by the leakage effect. This paper |
|
presents
a wavelet-based algorithm for voltage flicker analysis. The algorithm can |
|
accurately
extract the voltage flicker components by the direct demodulation of the |
|
voltage
signal. The performance characteristics of the algorithm are evaluated
with |
|
examples
of appropriate simulated and field data. The results illustrate the
proposed |
|
algorithm
is free of leakage effect problems.
|
|
A
de-noising scheme for enhancing wavelet-based power quality monitoring |
|
Hong-Tzer
Yang; Chiung-Chou Liao |
|
Power
Delivery, IEEE Transactions on , Volume: 16 Issue: 3 , July 2001 |
|
By
means of the wavelet transform (WT), a power quality (PQ) monitoring
system could |
|
easily
and correctly detect and localize the disturbances in the power systems.
However, |
|
the
signal under investigation is often corrupted by noises, especially the
ones with |
|
overlapping
high-frequency spectrum of the transient signals. The performance of the
WT |
|
in
detecting the disturbance would be greatly degraded, due to the difficulty
of |
|
distinguishing
the noises and the disturbances. To enhance the capability of the WT-based |
|
PQ
monitoring system, this paper proposes a de-noising approach to detection
of |
|
transient
disturbances in a noisy environment. In the proposed de-noising approach,
a |
|
threshold
of eliminating the influences of noises is determined adaptively according
to the |
|
background
noises. The abilities of the WT in detecting and localizing the
disturbances |
|
can
hence be restored. To test the effectiveness of the developed de-noising
scheme, |
|
employed
were diverse data obtained from the EMTP/ATP programs for the main |
|
transient
disturbances in the power systems as well as from actual field tests.
Using the |
|
approach
proposed in this paper, remarkable efficiency of monitoring the PQ
problems |
|
and
high tolerance to the noises are approved.
|
|
Antidistortion
method for wavelet transform filter banks and nonstationary |
|
power
system waveform harmonic analysis |
|
Generation,
Transmission and Distribution, IEE Proceedings- , Volume: 148 Issue: 2 , |
|
A
method is presented for eliminating the effect of imperfect frequency
response of the |
|
filters
in wavelet transform (WT) filter banks, and a WT-based algorithm for
harmonic |
|
analysis
of nonstationary power system waveforms. The method recovers the signal |
|
magnitude,
which is distorted due to the imperfect response of filters. The WT-based |
|
algorithm
is then developed. The algorithm is incorporated with the above
antidistortion |
|
method
to give accurate harmonic magnitudes. The power and practicality of the |
|
algorithm
are illustrated through its application for the diagnosis of a motor-starting |
|
problem,
which occurred in the Western Australia power system.
|
|
Monitoring
HVDC systems using wavelet multi-resolution analysis |
|
Gaouda,
A.M.; El-Saadany, E.F.; Salama, M.M.A.; Sood, V.K.; Chikhani, A.Y. |
|
Power
Systems, IEEE Transactions on |
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The paper
presents a disturbance classification technique
based on wavelet multi-resolution
analysis. The waveletmulti-resolution
transform is introduced as a tool for providing
discriminative, translation-invariant
features with small dimen-sions
disturbances in an HVDC
transmission
monitored on both DC and AC sides
of the HVDC system. It is
promising features that can
classify different disturbances that may occur anywhere in the
HVDC system.
|
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On-line
disturbance classification using nearest neighbor rule |
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A. M.
Gaouda, S. H. Kanoun and M. M. A. Salama |
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Electric
Power Systems Research, Volume 57, Issue 1, 31 January 2001, Pages 1-8 |
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This
paper presents an automated on-line disturbance classification technique
for different |
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power
quality problems. This technique is based on wavelet multi-resolution
analysis and |
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nearest
neighbors pattern recognition method. The wavelet-multi-resolution
transform is |
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introduced
as a powerful tool for feature extraction. It has the ability to extract |
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discriminative,
translation invariant features with small dimensionality in order to
classify |
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different
disturbances. The nearest neighbor pattern recognition technique is then |
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implemented
to classify different disturbances and evaluate the efficiency of the
extracted |
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Proposed
wavelet-neurofuzzy combined system for power quality violations |
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Elmitwally,
A.; Farghal, S.; Kandil, M.; Abdelkader, S.; Elkateb, M. |
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Generation,
Transmission and Distribution, IEE Proceedings- , Volume: 148 Issue: 1 ,
Jan. |
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A
system for the identification of power quality violations is proposed. It
is a two-stage |
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system
that employs the potentials of the wavelet transform and the adaptive
neurofuzzy |
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networks.
For the first stage, the wavelet multiresolution signal analysis is
exploited to |
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denoise
and then decompose the monitored signals of the power quality events to
extract |
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its
detailed information. A new optimal feature-vector is suggested and
adopted in |
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learning
the neurofuzzy classifier. Thus, the amount of needed training data is
extensively |
|
reduced.
A modified organisation map of the neurofuzzy classifier has significantly |
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improved
the diagnosis efficiency. Simulation results confirm the aptness and the |
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capability
of the proposed system in power quality violations detection and automatic |
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Unified
power quality conditioner with a novel control algorithm based on |
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Elnady,
A.; Goauda, A.; Salama, M.M.A. |
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Electrical
and Computer Engineering, 2001. Canadian Conference on , Volume: 2 , 2001 |
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Power
quality problems have received a great attention nowadays because of their
bad |
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economical
impacts on both utilities and costumers. The current harmonics are the
most |
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common
power quality problem, and the voltage sag is the most severe one. This
paper |
|
introduces
a new control algorithm based on wavelet transform for Unified Quality |
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Conditioner
(UPQC) to supress current harmonics and voltage sags. The proposed |
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control
algorithm is verified by digital simulation results using PSCAD/EMTDC
|
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Visualizing
time-varying power system harmonics using a Morlet wavelet |
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Shyh-Jier
Huang and Cheng-Tao Hsieh |
|
Electric
Power Systems Research, Volume 58, Issue 2, 21 June 2001, Pages 81-88 |
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In
this paper, a Morlet wavelet transform approach for the study of time-varying
power |
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system
harmonics is proposed. By this method, because the time¯frequency
localization |
|
characteristics
are embedded in wavelets, the time and frequency information of a |
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waveform
can be simultaneously presented as a visualized scheme. Different from the |
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fast
Fourier transform, the wavelet transform approach is more efficient in
monitoring the |
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signals
of interest when time varies. The proposed method has been applied to
visualize |
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inrush
current harmonics of transformers and to investigate arc-furnace-generated |
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signals.
From the test results, the merits of the proposed method have been
demonstrated |
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Wavelet
and neural structure: a new tool for diagnostic of power system |
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Borras,
D.; Castilla, M.; Moreno, N.; Montano, J.C. |
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Industry
Applications, IEEE Transactions on , Volume: 37 Issue: 1 , Jan.-Feb. 2001 |
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The
Fourier transform can be used for the analysis of nonstationary signals,
but the |
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Fourier
spectrum does not provide any time-domain information about the signal.
When |
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the
time localization of the spectral components is needed, a wavelet
transform giving the |
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time-frequency
representation of the signal must be used. In this paper, using wavelet |
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analysis
and neural systems as a new tool for the analysis of power system
disturbances, |
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disturbances
are automatically detected, compacted and classified. An example showing |
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the
potential of these techniques for diagnosis of actual power system
disturbances is |
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Experimental
performance evaluation of a wavelet-based on-line voltage |
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detection
method for power quality applications |
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Mokhtari,
H.; Karimi-Ghartemani, M.; Iravani, M.R. |
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IEEE
Transactions on Power Delivery, Vvol. 17, No. 1 , Jan. 2002, pp.pp.
1161-172. |
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This
paper evaluates performance of a wavelet-based, on-line (real-time)
voltage |
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detection
scheme for power quality applications. The objectives are: 1) to
demonstrate |
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suitability
of the proposed method in detecting faults/disturbances in a power system
and |
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2) to
compare its performance with that of a con-ventional |
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scheme.
Two (STS) systems are chosen as frameworks for comparison; a low-voltage |
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laboratory
STS setup for which measured results are provided, and a medium-voltage |
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STS
system for which detection times are derived based on simulation, using
the |
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