This document analyzes the modeling of overhead transmission lines for lightning studies. It summarizes guidelines for modeling transmission line components like towers, grounding impedance, and insulator strings. It then models a 400kV transmission line in Albania using these guidelines. Simulation results show that towers with higher characteristic impedance and grounding resistance experience lower peak lightning currents. Accurately modeling transmission line components is important for evaluating lightning performance and maintenance.
Modelling Optical Waveguide Bends by the Method of LinesTELKOMNIKA JOURNAL
A rigorous analytical and semi analytical method of lines has been used to calculate the
transverse-electric field attenuation coefficient of guided mode as it travels in waveguide bends structure.
Both approaches then were compared to get a better understanding on how the attenuation behaves along
single curve waveguides with constant radius of curvature. The Helmholtz Equation in polar coordinate
was transformed into a curvalinier coordinate to simulate the waveguide bends using the method of line
analysis. The simple absorption boundary conditions are used into the method of lines to demonstrate
evanescent field of the guided mode nature as its travels in waveguide bends structures. The results show
that a reasonable agreement between both theoretical approaches.
Polarization insensitive switchable metamaterial absorber/reflector for X-ban...journalBEEI
A unit cell of squared shaped polarization-insensitive switchable metamaterial absorber/reflector is presented. The structure operates at 10.20 GHz under both absorber mode and reflector mode configurations. Copper wire bridging the gaps to form a circular shape structure were used as switches for operation mode selections. The structure was designed on an FR4 substrate, and the incidental wave angles were varied from 0 to 50 degrees. The structure demonstrated almost 100% absorption at resonance, 3.314 GHz percentage bandwidth at 80% as an absorber. On the other hand, as reflector, it demonstrated almost a 90% reflection and a usable bandwidth of 3.327 GHz.
Power system is the transfer of electricity from generation to the point of user location. Power system is composed of generation of power, its transmission and distribution. Transmission system is the main part out of these three in which mostly losses occur. The unchanging factors of the transmission line on which these losses depend are inductance, resistance and capacitance. These constants or unchanging factors play a vital role in the performance of transmission line. For example the capacitance effect will be more and its performance will be affected if the height of transmission line is less from the ground. On the other hand its capacitance will be less but tension will be high if the height of the transmission is high. For this reason a transmission line is connected in a curved or catenary shape known as sag. To minimize tension sag is provided in a transmission line. Sag and tension must be adjusted in safe limits. This immediate paper gives a simulation structure to calculate sag and tension of AAAC (All Aluminum Alloy Conductors of overhead transmission lines with same span length for minimum operating temperature. Three different cases are presented with different towers height and are explained in detail for unequal level span. The results show that the tension and sag increased with height. So great the height difference, higher tensions upon higher towers.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
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Modelling Optical Waveguide Bends by the Method of LinesTELKOMNIKA JOURNAL
A rigorous analytical and semi analytical method of lines has been used to calculate the
transverse-electric field attenuation coefficient of guided mode as it travels in waveguide bends structure.
Both approaches then were compared to get a better understanding on how the attenuation behaves along
single curve waveguides with constant radius of curvature. The Helmholtz Equation in polar coordinate
was transformed into a curvalinier coordinate to simulate the waveguide bends using the method of line
analysis. The simple absorption boundary conditions are used into the method of lines to demonstrate
evanescent field of the guided mode nature as its travels in waveguide bends structures. The results show
that a reasonable agreement between both theoretical approaches.
Polarization insensitive switchable metamaterial absorber/reflector for X-ban...journalBEEI
A unit cell of squared shaped polarization-insensitive switchable metamaterial absorber/reflector is presented. The structure operates at 10.20 GHz under both absorber mode and reflector mode configurations. Copper wire bridging the gaps to form a circular shape structure were used as switches for operation mode selections. The structure was designed on an FR4 substrate, and the incidental wave angles were varied from 0 to 50 degrees. The structure demonstrated almost 100% absorption at resonance, 3.314 GHz percentage bandwidth at 80% as an absorber. On the other hand, as reflector, it demonstrated almost a 90% reflection and a usable bandwidth of 3.327 GHz.
Power system is the transfer of electricity from generation to the point of user location. Power system is composed of generation of power, its transmission and distribution. Transmission system is the main part out of these three in which mostly losses occur. The unchanging factors of the transmission line on which these losses depend are inductance, resistance and capacitance. These constants or unchanging factors play a vital role in the performance of transmission line. For example the capacitance effect will be more and its performance will be affected if the height of transmission line is less from the ground. On the other hand its capacitance will be less but tension will be high if the height of the transmission is high. For this reason a transmission line is connected in a curved or catenary shape known as sag. To minimize tension sag is provided in a transmission line. Sag and tension must be adjusted in safe limits. This immediate paper gives a simulation structure to calculate sag and tension of AAAC (All Aluminum Alloy Conductors of overhead transmission lines with same span length for minimum operating temperature. Three different cases are presented with different towers height and are explained in detail for unequal level span. The results show that the tension and sag increased with height. So great the height difference, higher tensions upon higher towers.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
We connect Students who have an understanding of course material with Students who need help.
Benefits:-
# Students can catch up on notes they missed because of an absence.
# Underachievers can find peer developed notes that break down lecture and study material in a way that they can understand
# Students can earn better grades, save time and study effectively
Our Vision & Mission – Simplifying Students Life
Our Belief – “The great breakthrough in your life comes when you realize it, that you can learn anything you need to learn; to accomplish any goal that you have set for yourself. This means there are no limits on what you can be, have or do.”
Like Us - https://www.facebook.com/FellowBuddycom
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Recently there is growing interest in a new technol
ogy, substrate integrated waveguide (SIW), it
has been applied successfully to the conception of
planar compact components for the
microwave and millimeter waves applications. In thi
s study, a V-band substrate integrated
waveguide power divider, circulator and coupler are
conceived and optimized by Ansoft HFSS
code. Thus, through this modeling, design considera
tions and results are discussed and
presented. Attractive features including compact si
ze and planar form make these devices
structure easily integrated in planar circuits.
Offset effect on the S-Bend structure losses and optimization of its size for...IJECEIAES
The S-Bend structures are heavily exploited to join optical components. Reducing the power loss caused by the curve is the main objective in the design step of these components. However integrated optical circuits require S-Bend waveguide to be low loss and compact sized. In this paper, we present a contribution to link the curved structure to the straight waveguide by using the simulated bend function available in the Beam propagation tool of the Rsoft commercial software package. Simulation results confirm that this approach allows a reduction of the size of the curved structure with offset with relatively minimum of losses for photonic field.
COUPLER, POWER DIVIDER AND CIRCULATOR IN V-BAND SUBSTRATE INTEGRATED WAVEGUID...ijcsa
In recent years substrate integrated waveguide technology (SIW) has been applied successfully to the conception of planar compact components for the microwave and millimeter waves applications. In this study, a V-band substrate integrated waveguide coupler, power divider and circulator are conceived and optimized by Ansoft HFSS code. Thus, through this modeling, design considerations and results are discussed and presented. Attractive features including compact size and planar form make these devices structure easily integrated in planar circuits
Substrate integrated waveguide power divider, circulator and coupler in [10 1...ijistjournal
The Substrate Integrated Waveguide (SIW) technology is an attractive approach for the design of high
performance microwave and millimeter wave components, as it combines the advantages of planar
technology, such as low fabrication costs, with the low loss inherent to the waveguide solution. In this
study, a substrate integrated waveguide power divider, circulator and coupler are conceived and optimized
in [10-15] GHz band by Ansoft HFSS code. Thus, results of this modeling are presented, discussed and
allow to integrate these devices in planar circuits.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Recently there is growing interest in a new technol
ogy, substrate integrated waveguide (SIW), it
has been applied successfully to the conception of
planar compact components for the
microwave and millimeter waves applications. In thi
s study, a V-band substrate integrated
waveguide power divider, circulator and coupler are
conceived and optimized by Ansoft HFSS
code. Thus, through this modeling, design considera
tions and results are discussed and
presented. Attractive features including compact si
ze and planar form make these devices
structure easily integrated in planar circuits.
Offset effect on the S-Bend structure losses and optimization of its size for...IJECEIAES
The S-Bend structures are heavily exploited to join optical components. Reducing the power loss caused by the curve is the main objective in the design step of these components. However integrated optical circuits require S-Bend waveguide to be low loss and compact sized. In this paper, we present a contribution to link the curved structure to the straight waveguide by using the simulated bend function available in the Beam propagation tool of the Rsoft commercial software package. Simulation results confirm that this approach allows a reduction of the size of the curved structure with offset with relatively minimum of losses for photonic field.
COUPLER, POWER DIVIDER AND CIRCULATOR IN V-BAND SUBSTRATE INTEGRATED WAVEGUID...ijcsa
In recent years substrate integrated waveguide technology (SIW) has been applied successfully to the conception of planar compact components for the microwave and millimeter waves applications. In this study, a V-band substrate integrated waveguide coupler, power divider and circulator are conceived and optimized by Ansoft HFSS code. Thus, through this modeling, design considerations and results are discussed and presented. Attractive features including compact size and planar form make these devices structure easily integrated in planar circuits
Substrate integrated waveguide power divider, circulator and coupler in [10 1...ijistjournal
The Substrate Integrated Waveguide (SIW) technology is an attractive approach for the design of high
performance microwave and millimeter wave components, as it combines the advantages of planar
technology, such as low fabrication costs, with the low loss inherent to the waveguide solution. In this
study, a substrate integrated waveguide power divider, circulator and coupler are conceived and optimized
in [10-15] GHz band by Ansoft HFSS code. Thus, results of this modeling are presented, discussed and
allow to integrate these devices in planar circuits.
Prediction of Fault in Distribution Transformer using Adaptive Neural-Fuzzy I...ijsrd.com
In this paper, we present a new method for simultaneous diagnosis of fault in distribution transformer. It uses an adaptive neuro-fuzzy inference system (ANFIS), based on Dissolved Gas Analysis (DGA). The ANFIS is first “trained†in accordance with IEC 599, so that it acquires some fault determination ability. The CO2/CO ratios are then considered additional input data, enabling simultaneous diagnosis of the type and location of the fault. Diagnosis techniques based on the Dissolved Gas Analysis (DGA) have been developed to detect incipient faults in distribution transformers. The quantity of the dissolved gas depends fundamentally on the types of faults occurring within distribution transformers. By considering these characteristics, Dissolved Gas Analysis (DGA) methods make it possible to detect the abnormality of the transformers. This can be done by comparing the Dissolved Gas Analysis (DGA) of the transformer under surveillance with the standard one. This idea provides the use of adaptive neural fuzzy technique in order to better predict oil conditions of a transformer. The proposed method can forecast the possible faults which can be occurred in the transformer. This idea can be used for maintenance purpose in the technology where distributed transformer plays a significant role such as when the energy is to be distributed in a large region.
ANALYSIS OF LIGHTNING STRIKE WITH CORONA ON OHTL NEAR THE SUBSTATION BY EMTP ADEIJ Journal
Lightning protection and insulation coordination of transmission lines and substations require an accurate
knowledge of the magnitudes and waveforms of lightning overvoltage. To simulate the lightning
overvoltage precisely near the substation, this study has shown how to consider the lightning impulse
corona for distortion effect of this overvoltage.
IRJET-Sensitivity Analysis of Maximum Overvoltage on Cables with Considering ...IRJET Journal
Hamed Touhidi ,Mehdi Shafiee, Behrooz Vahidi,Seyed Hossein Hosseinian, "Sensitivity Analysis of Maximum Overvoltage on Cables with Considering Forward and Backward Waves ", International Research Journal of Engineering and Technology (IRJET), Vol2,issue-01 April 2015. e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
lightning is known to be one of the primary sources of most surges in high keraunic areas. It is well-known fact that surge overvoltage is a significant contribution in cable failures. The other source of surge voltage is due to switching and it is pronounce on extra high voltage power transmission systems. The effect of both lightning and switching surges is weakening the cable insulation. The progressive weakening of such insulation will lead to cable deterioration and eventually its failure. Each surge impulse on the cable will contribute with other factors towards cable insulation strength deterioration and ultimately cable can fail by an overvoltage level below the cable basic impulse level (BIL). The maximum lightning overvoltage for a given cable depends on a large number of parameters. This paper presents the effect of model parameters (e.g., rise time and amplitude of surge, length of cable, resistivity of the core and sheath, tower footing resistance, number of sub conductors in the phase conductor (bundle), effect of surge arrester, length of lead, relative permittivity of the insulator material outside the core, power frequency voltage, stroke location, cable joints, shunt reactors, sheath thickness) on maximum cable voltage. The simulations show that the maximum overvoltage.
Analysis and optimization of wireless power transfer linkAjay Kumar Sah
In this paper, a high efficiency Gallium nitride (GaN), HEMT (High Electron Mobility Transistor) class-E power amplifier for the wireless power transfer link is designed and simulated on PSpice. A four-coil wireless power transfer link is modeled for maximum power transfer efficiency on ADS (Advanced Design System) and frequency splitting phenomenon is demonstrated, explained and analyzed. Two resonant coupling structures, series & mixed, are presented and compared. The efficiency performance of the link is studied using spiral and helical antennas of different wire make. In addition, techniques for improving efficiency of the wireless power transfer systems with changing coupling coefficient viz. frequency splitting phenomenon of the coils are proposed.
Fea of pcb multilayer stack up high voltage planar transformer for aerospace...elelijjournal
High voltage planar transformer is a technology which can replace conventional transformer with its distinct advantages of saturation and cost efficiency. This paper includes, study and solution methods for PCB winding configuration in planar magnetic elements with multilayer
stack up of PCB Cu-tracks, producing High voltage power supply for aerospace application.With finite element analysis (FEA) simulations, different simulation outcomes are discussed for inspecting flux intensity and current density distribution with computing Electric field strength
and Magnetic fields. In principal conclusion of study, complete analysis and some practical design guidelines for
multilayer PCB stack up are discussed in this paper.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Planar transmission line is one of the physical medium used to transmit high frequency signal. The signal flow through the transmission line depends on the important electrical parameter, the frequency. As the signal frequency increases in a conductor, current carriers start to move towards the edges of the conductor. Flow of carriers on the conductor synchronizes with the substrate to achieve better efficiency. The signal flow in the transmission line depends on the dielectric constant of the material and the loss tangent value. The paper shows the simulation studies on return loss and insertion loss of planar transmission lines with constant frequency of 10GHz. To design planar transmission lines different dielectric materials are being selected. In our design, parameters like input impedance, conductor (silver) thickness and conductor height are kept constant. The design and analysis is done using Applied Wave Research (AWR) tool. The obtained results shows unique response and it depends on the type of dielectric medium selected.
Towards An Accurate Modeling of Frequency-dependent Wind Farm Components Unde...IJAPEJOURNAL
Frequency dependence complete model is set up for describing the lightning transient behavior of the wind turbines (WTs).To get an appropriate wind turbine model, a high frequency models of surge arrester protecting the boost transformer, transformer and ground electrode soil ionization are implemented. The transient responses and Ground Potential Rise (GPR) can be obtained at different locations in the WTs and connected grid in the time domain as well as in the frequency domain using Fast Fourier Transform (FFT). To check the validity of the model, Surge arresters protection level at different locations, at i.e. LV, MV and HV, is compared with ABB manufacture data sheet, Also a comparison has been made between simple and frequency dependence model of overall wind farm components using ATP/EMTP. This paper provides an accurate simulation of wind farm components under transient condition.
The purpose of this paper is to study and design of 230 kV twin bundle double circuit overhead transmission line. In design consideration, the selection of economic voltage, choice of conductor size, number of insulators, maximum sag of conductor and minimum height of conductor are considered. The electrical transfer of energy from one place to another over long distance with standard regulations is one of the major problems in the field of electrical power engineering. The parameters of overhead transmission line are resistance, inductance and capacitance. The bundle conductors are used for reducing the reactance on the line, corona losses, radio interference and surge impedance. Daw Hnin Yu Lwin | U Hla Myo Htay "Design of 230 kV Twin Bundle Double Circuit Overhead Transmission Line" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27830.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/27830/design-of-230-kv-twin-bundle-double-circuit-overhead-transmission-line/daw-hnin-yu-lwin
A Study of Thermal Behaviour of HTS Devices at Alternating Current IJECEIAES
The paper presents a study on thermal behavior of a coil made of a hightemperature supercon-ducting tape representing operation of a superconducting device (for example, a transformer). Based on the results of a physical experiment, a mathematical model of superconducting coil operation under short circuit conditions at the load side was developed. Regimes of overheating by variable short circuit currents were investigated. In this case, short circuit current amplitudes ex-ceeded a critical current of a superconductor, and coil parameters (e.g. an average nonlinearity parameter of a current-voltage characteristic, a superconductor length, and others) were varied. Permissible overheating for a coil with the possibility of its return into the superconducting state after emergency conditions in a dead-time period of automatic reclosing was considered. A crite-rion for return of a superconducting device into the superconducting state within a dead-time period of automatic reclosing has been obtained.
Transient voltage distribution in transformer winding (experimental investiga...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Transient voltage distribution in transformer winding (experimental investiga...eSAT Journals
Abstract In this work, the non-liner voltage distribution in transformer winding is investigated that occurs due switching and lightning. Transformer winding is modeled in the alternative transients program (ATP) version of Electromagnetic transients program (EMTP-RV). EMTP software is used to simulate the very fast transient overvoltage. An experimental setup that consist of , Recurrent surge generator, CRO and transformer winding model has been developed and voltages measured at different point along the transformer winding. Simulation results show good agreement with the experimental result. Index Terms: Very fast transient overvoltages, internal resonance, impulse voltage distribution, disc winding
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
Le nuove frontiere dell'AI nell'RPA con UiPath Autopilot™UiPathCommunity
In questo evento online gratuito, organizzato dalla Community Italiana di UiPath, potrai esplorare le nuove funzionalità di Autopilot, il tool che integra l'Intelligenza Artificiale nei processi di sviluppo e utilizzo delle Automazioni.
📕 Vedremo insieme alcuni esempi dell'utilizzo di Autopilot in diversi tool della Suite UiPath:
Autopilot per Studio Web
Autopilot per Studio
Autopilot per Apps
Clipboard AI
GenAI applicata alla Document Understanding
👨🏫👨💻 Speakers:
Stefano Negro, UiPath MVPx3, RPA Tech Lead @ BSP Consultant
Flavio Martinelli, UiPath MVP 2023, Technical Account Manager @UiPath
Andrei Tasca, RPA Solutions Team Lead @NTT Data
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Securing your Kubernetes cluster_ a step-by-step guide to success !
H010526975
1. IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE)
e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 10, Issue 5 Ver. II (Sep – Oct. 2015), PP 69-75
www.iosrjournals.org
DOI: 10.9790/1676-10526975 www.iosrjournals.org 69 | Page
The Lightning Study of Overhead Transmission Lines
Marjola Puka1
, Nako Hobdari2
1
Lecturer, ElectrotechnicDepartment,Tirana, Albania
2
Profesor, Eletric Power SystemDepartment,Electrical Engineering Faculty, Polytechnic University of Tirana,
Abstract: The focus of this paper is the analysis of lightning in Overhead Transmission Lines. By testing a real
line of the Albanian transmission network, the paper treats the effect that modelingand the parameters of line
can have on the lightning performance, especially on the peak currents during flashover phenomena. This is a
very important aspect to evaluate the lightning protection and maintenance of power transmission lines.
Keywords: lightning, modeling, insulation coordination, transmission lines
I. Introduction
Based on insulation coordination guidelines[1], the procedure of evaluating the lightning performance
of a power transmission line consists of the following steps: a) generation of random numbers to obtain the
parameters of lightning strokes and the parameters of line, b) application of an incidence model to deduce the
point of impact of the return stroke; c) calculation of the overvoltage generated by each stroke, depending on the
point of impact; d) calculation of the flashover rate. The procedure must be performed with limitations and
uncertainties, e.g. the knowledge of the lightning parameters is usually incomplete. These limitations can be
partially overcome by performing a parametric study that could detect those parameters for which an accurate
knowledge is required. This paper analyses the limitations related to the representation of an overhead
transmission line in lightning calculations.
This paper presents a presentation at ATP program to a sensitive study whose main goal is to determine
the effect that the model and the parameters selected for the presentation of the main parts of a transmission line
can have on the flashover rate. The models whose effects is analyzed are those used to represent the tower, the
grounding impedance and the insulator strings.
II. A summary of modeling the power transmission lines
The modeling guidelines for lightning transient analysis can be summarized as follows [2]:
The transmission line has to be represented by means of several multi-phase untransposed distributed-
parameters line spans at both side of the point of impact. This representation can be made by using
either a frequency-dependent or a constant parameter model.
A line termination is needed at each side of the above model to prevent reflections thatcould affect the
simulated overvoltages. This can be realized by adding a long enough line section at each side.
Tower models have been developed using a theoretical approach or an experimental work. They can be
classified into the three groups described as below[3]:
a)Single vertical lossless line models: The tower is represented by means of a simple geometric form. The
model that is implemented in the Flash program is based on the model recommended by CIGRE.
b)Multi-conductor vertical line models: Each segment of the tower between cross-arms is represented as a
multi-conductor vertical line, which is reduced to a single conductor. The tower model is then a single-phase
line whose section increases from top to ground, as shown in fig.1. The model shown in fig.2 includes the effect
of bracings (represented as lossless lines in parallel to the main legs) and cross-arms (represented as a lossless
line branched at junction points).
c)Multistory model: It is composed of four sections that represent the tower sections between cross-arms. Each
section consists of a lossless line in series with a parallel R-L circuit, included for attenuation of the travelling
waves, as shown in fig. 3. This model is especially appropriate for the overhead transmission lines with voltages
over 400kV [4],[5].
An accurate model of the grounding impedance has to account for a decrease of the resistance value as
the discharge current value increases. It is accepted that the resistance value is greater for small
lightning currents, and its variation with respect the low current and the low frequency values is only
significant for large soil resistance. When the soil ionization is not incorporated, the grounding
impedance model can be approximated by a nonlinear resistance:
2. The Lightning Study of Overhead Transmission Lines
DOI: 10.9790/1676-10526975 www.iosrjournals.org 70 | Page
0
1
g
R
R
I
I
(1)
Where: 0
R the grounding resistance at low current and low frequency; g
I the limited current to
initiate the sufficient soil ionization; I the stroke current through the resistance.
Fig.1Multiconductor vertical line model
Fig.2Multiconductor vertical line model including bracings and cross-arms
3. The Lightning Study of Overhead Transmission Lines
DOI: 10.9790/1676-10526975 www.iosrjournals.org 71 | Page
Fig.3Multistory model
The limited current is calculated as follows:
0
2
0
2
g
E
I
R
(2)
Where: is the soil resistivity (ohm-m); 0
E the soil ionization gradient (about 400kV/m).
The insulator string model can be based on the leader progression model or on a simple voltage-
dependent flashover switch with a random behavior.
Using the first approach, streamers propagate along the insulator string when the applied voltage exceeds the
corona inception voltage; if the voltage remains high enough, these streamers will become a leader channel. A
flashover occurs when the leader crosses the gap between the cross-arm and the conductor.
The total time to flashover can be expressed as follows:
t c s l
t t t t
(3)
Where: c
t is the corona inception time; s
t the streamer propagation time; l
t the leader propagation time. Usually
c
t is neglected, while s
t is calculated as follows:
5 0
5 0
1 .2 5 0 .9 5
s
E
t
E E
(4)
Where: 5 0
E is the average gradient at the critical flashover voltage and E is the maximum gradient in the gap
before breakdown. The leader propagation time l
t can be obtained from the following equation:
0
( )
( )l l
dl v t
k v t E
dt g l
(5)
Where: ( )v t is the voltage across the gap; g is the gap length; l is the leader length; 0l
E is the
critical leader inception gradient and l
k is the leader coefficient. The leader propagation stops if the gradient in
the unbridged part of the gap falls below 0l
E .
The lightning stroke is represented as a current source. Fig.4 shows the concave form of standard
impulse used for lightning study of transmission lines.
4. The Lightning Study of Overhead Transmission Lines
DOI: 10.9790/1676-10526975 www.iosrjournals.org 72 | Page
Fig.4The standard impulse of lightning stroke
(I100= peak currentmagnitude;tf =1.67(t90-t30)= rise time;th tail time
If lightning stroke parameters are assumed independently distributed, their statistical behavior can be
approximated by a long-normal distribution with the following probability density function:
2
lnln
ln ln1
( ) exp 0.5
2
m
xx
x x
p x
x
(6)
Where: ln x
is the standard deviation of ln x , and m
x is the average value of x.
III. The studied line
The object of the study is a line of the Albanian Transmission Network: the 400kV transmission line
“Tirana-Podgorica”[7]. It is a line with two conductors per phase (with main characteristics as shown in Table I)
and with tower design as shown in fig 5.
Table I :Characteristics of Phase Conductors and Shield Wires
Type Diameter
(cm)
Resistance
(Ω/km)
Phase Conductors ACSR 3.06 0.01
Shield wires OPGW 1.6 0.299
Fig.5Tower configuration of 400kV line “Tirana-Podgorica”
5. The Lightning Study of Overhead Transmission Lines
DOI: 10.9790/1676-10526975 www.iosrjournals.org 73 | Page
IV. Modeling and simulating results
-Based on the real electro-geometrical data, a section of the overhead transmission line is modeled in
ATP software with a constant distributed parameters model[6], [7], as shown in fig.6.
-The towers are represented by multistory model, which is chosen the most appropriate for the real
case-study: based on the aim of lightning study, the linear voltage 400kV, and the height of towers which is
higher than 30m.
-The representation of insulators string is modeled in FLASH program, based on their dimensions and
characteristics (see fig.7).
-The soil resistivity is considered uniform 100 Ωm, and the soil gradient 400kV/m
-The line is simulated in different points of impact with different lightning impulses. The results of
simulating are summarized in the table II: for every tower (with specific parameters), we have studied the peak
current magnitudes depending on characteristic impedance and the grounding resistance. As can be noted from
the charts shown in fig. 8 and fig.9, it can result that the lower peak current magnitude belongs to the towers
with greater value of characteristic impedance and grounding resistance. Based on the real geometrical
dimensions for the simulated towers, these characteristics belong to the towers with greater height and smaller
perimeter.
Fig.6Modeling of the line tested in ATP software
Fig.7Insulators Model in FLASH program
TABLE II : A Summary of Simulating Results
Tower
Type
Peak Current Magnitude (kA) Tower No. Characteristic impedance (Ω) Grounding
Resistance (Ω)
2NS+0 50 250 159.6 10.4
2NS-6 38.37 251 154 10.61
2NS-6 38.23 253 154 8.95
2LA-6 56 253 138.47 9.63
2NS-6 39.34 254 154 10.47
2NS-6 37.56 255 154 9.1
2HS+6 40 256 166.46 4.52
2HS+3+2 39 257 165.76 3.64
2HS-6 45 258 157.75 7.35
2HS-3 44 259 160 5.77
2LA+0 56 260 144.2 9.66
2NS+0 41 261 159.63 10.48
2HS+0 38 262 162.2 10.64
2MA+3 46 263 145 4.18
2HS-3 38 264 160 10.1
6. The Lightning Study of Overhead Transmission Lines
DOI: 10.9790/1676-10526975 www.iosrjournals.org 74 | Page
2HS+0 37 265 168.54 10.83
2LA+6-1 47 266a 148.66 7.8
2HS+9 36 266b 168.54 5.54
2HS+0 38 266c 162.2 4.54
2NS+3 39 266d 162.3 5.18
2LA-6 50 267 138.47 5.51
2NS+0 42 268 159.63 4.69
2NS+3 39 269 162.3 0.89
2NS+0 44 270 146.2 2.89
2NS-3 41 271 156.9 1.72
2NS-6 43 272 150.36 3.93
2LA-6 53 273 138.47 4.47
Fig.8 Peak Current Magnitude for the simulated towers
Fig.9Characteristic impedance (with red color) and grounding resistance (with blue color)for the simulated towers
Peak Current Magnitude (kA)
Characteristic Impedance and Grounding Resistance
Tower No.
Characteristic
ImpedanceGrounding
Resistance
7. The Lightning Study of Overhead Transmission Lines
DOI: 10.9790/1676-10526975 www.iosrjournals.org 75 | Page
V. Conclusion
This paper presents a sensitive case of lightning study for overhead transmission line, which is very
important for operation maintenance of this main component of power system.
The analysis of lightning transients requires an accurate modeling of line which is represented by
towers, insulators and grounding impedance.
By modeling in ATP software a real overhead transmission line of the Albanian power system, the
paper shows some interesting results about the relations between peak current magnitudes of lightning and
towers parameters which are expressed through their characteristic impedance and grounding resistance.
References
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2010), 17-128
[4] F.J Mo, Y.P Chen, J.J Ruan, Study of Transmission Tower Models and Their Lightning Performance, Power System Technology,
28 (2010), 80-84
[5] M.Ishii at al., Multistory transmission tower model for lightning surge analysis, Calculation. IEE Tran. On Power Delivery, vol.6,
no.3 (1991), 1327-1335
[6] L.M Dudurych, T.J.Gallager, J.Corbett, M.V.Escudero, EMTP analysis of the lightning performance of a HV transmission line,
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[7] OST (Albanian Transmission Operator), As Built Documentation of 400kV Transmission Line Tirana-Podgorica, (OST Archive,
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