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Register a new userالتحميل غير المتزن لمراكز التحويل الكهربائية و طرق معالجته
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Added by
Damascus University ورقة بحثية
Publication date
2001
fields
Electrical Power Engineering
and research's language is
العربية
Created by
Shamra Editor
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يتلخص مضمون هذا البحث في دراسة التباين في أحمال محولات القوى في مراكز التحويل الكهربائية ، و ما ينجم عن هذا التوزيع غير المنتظم للأحمال من مخاطر و أضرار لمنتج و مستهلك القدرة الكهربائية من الناحيتين الفنية و الاقتصادية ، و لاسيَّما عندما يتحول إلى تحميل غير متزن للأطوار ، مما يؤدي بدوره إلى ارتفاع الضياعات و انخفاض الوثوقية .
No English abstract
References used
Fabrycky, W. J. & Thuesen, G .J. – Engineering Economy, 6th ed., Prentice-Hall, Englewood Cliffs, New Jersey, 1984
EL- Hawary, M. E. & Christensen, G. S. – Optimal economic operation of electrical power, California Institute of Technology, 1979
Weedy, B. M. – Electric Power Systems .Massachusets Institute of Technology, 1989
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There are tens of power transformers working in the Syrian high voltage network with rated voltage over 11 kV. and rated power over 10 MVA. These transformers have more than 15 years in service and since then only routine maintenance was carried on f
or this transformers.
IEC instructions and manufacturer instructions indicate that many tests, measurements and checking have to be done for transformers .But due to the fact that measuring apparatus and testing equipment are very sophisticated and very difficult to be found at sites where power transformers are mounted, the checking and the measuring of the transformer characteristics seem to be about impossible .
It is known that due to aging , the characteristics of electrical insulation materials used in high-voltage equipment are diminished and the probability that an electrical fault to appear is more evident .
To improve the running of power transformers in high-voltage network and to reset the characteristics of the insulation materials of power transformers to their nominal values, some new techniques are used to revitalize power transformers in their site at substations without moving them to specialized repair factory or workshop.
A digital watermark is a signal that is embedded into digital data
(text, image, audio, video) in a manner that allows it to be extracted
later. This is done by embedding a pattern which contains the
author's data into the digital data.
In this r
esearch, we propose a comparison between three types of
transformations for embedding a watermark in the frequency
domain into digital images in an efficient and secure method that
allows the watermarking any type of digital images with good
perceptibility.
Routing protocols play an essential role in meeting the quality of service
requirements in the network, but achieving these requirements may require frequent send
and receive operations to build and maintain routing tables, which consume sensors
r
esource If we take into consideration the limitations of wireless sensor networks in terms
of the amount of available energy and storage capacity.
In this research a performance comparison of the on-demand Distance Vector
Routing protocol AODV and Hierarchical Routing protocolHR was carried out in terms of
the packet delivery and loose rate, delay and jitter, and the amount of expended energy in
the Wireless sensor network operates according to IEEE802.15.4 standard in cases where
some of sensors get out of work for limited periods of time.
The results showed that the hierarchical routing protocols perform better in terms of
delay time and transfer rate and the amount of consumed energy than on-demand Distance
Vector Routing protocol routing protocol, but suffer larger packet loss due to routing path
corruption as a result of sensors crashes.
This research includes a numerical study using Finite Element Method aims to
evaluate the ability and accuracy of using Non-destructive Impact Response Method in the
assessment of length and cross-sections of intact concrete pile (not deformed) in
both time
and frequency domains. Therefore, an appropriate numerical model depends on the
modeling of both impact force (impulsive load) and distributing medium (pile + soil) and
insert them in computing software ABAQUS was carried out. The numerical model was
verified corresponding to field measures obtained from literature review and the results
showed good agreement between measures and numerical results. Furthermore, the model
was applied on a typical example in order to study vibration distribution in the pile due to
impulsive load applied on pile top. Mechanical response curve of intact pile was obtained.
Then, both of length and cross-section area of the pile were determined. Finally,
parametrical study of most important factors (stiffness of soil surrounding the pile and
length of pile embedded in the soil) effect on vibration distribution resulted from impulsive
load applied on pile top. The parametrical study was carried out in two domains; first one
was time domain depending on the direct analysis of particle displacement and velocity
and the second was frequency domain depending on analysis of pile mechanical response
curve. The results of this research enables to use the proposed numerical model to
numerically obtain the time history of particle displacement and velocity in addition to the
curve of mechanical response computed in the pile top and forms reference diagrams
which is used later to compare with similar diagrams resulted from field test of executed
piles. As a result, pile integrity test and detecting of defects in the piles if any. In addition,
the limits of the use of both analysis methods adapted in research and choose the best
between them according to the case study.
طريقة العناصر المنتهية
Finite element method
اختبار سلامة الأوتاد
تجارب الصدم غير المخربة
السجلات الزمنية للإهتزازات
تابع قابلية الحركة
منحني الإستجابة الميكانيكية للوتد
المجالين الزمني و الترددي
Pile Integrity Test
impulsive load
nondestructive impact tests
vibration time history
mobility function
pile mechanical response curve
time and frequency domains
ABAQUS
المزيد..
In this paper, we presents a solution for those problems by using (CAN)
protocol in ATM networks due to many features such as the priority of
access and lose-free bus arbitration. We designed a new application layer
for using (CAN) in ATM network.
Then we compared this proposal
pattern with the current ATM network by using MATLAB.
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