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Kasap, Huseyin. "Investigation Of Stockbridge Dampers For Vibration Control Of Overhead Transmission Lines." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614865/index.pdf.
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This thesis aims to examine the performance of Stockbridge dampers used to suppress aeolian vibrations on overhead transmission lines arising from the wind. In this respect, a computer program, based on the Energy Balance Method, is developed using MATLAB. The developed computer program has also a graphical user interface (GUI), which allows the program to interactively simulate Stockbridge damper performance for vibration control of overhead transmission lines. Field tests results obtained from literature are used in various case studies in order to validate and evaluate the developed software. Moreover, sample Stockbridge damper characterization tests, which then could be introduced to the software, are performed. A custom test fixture is designed due to its unavailability of commercial alternatives in the market. In the design of the test fixture, modal and transmissibility analyses are done by using ANSYS Workbench. To further validate the test setup, transmissibility test is done and consistent results with the transmissibility analyses are observed in the range of expected aeolian vibration frequencies. Finally, the stepped-sine and swept-sine tests are performed with and without damper for the characterization test, where the latter one is performed to eliminate the negative effects of the test setup. Both tests yield almost same damper power dissipation curves.
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Eskandarian, Mojtaba. "Ice shedding from overhead electrical lines by mechanical breaking : a ductile model for viscoplastic behaviour of atmospheric ice = Délestage de glace des câbles électriques par bris mécaniques : un modèle du comportement ductile viscoplastique de la glace atmosphérique poreuse /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2005. http://theses.uqac.ca.
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Filipovic-Gledja, Visnja. "A probability based unified model for predicting electrical, mechanical and thermal characteristics of stranded overhead-line conductors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30086.pdf.
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Bansal, Anurag. "Finite element simulation of mechanical characterization of composite insulators /." Full text open access at:, 1996. http://content.ohsu.edu/u?/etd,221.
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Nedoma, Jakub. "Vliv samonosného optického kabelu na mechaniku venkovního vedení VN." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442472.
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This thesis is focused on assessing the impact of retrofitting dielectric All Dielectric Self-Supporting Cable (ADSS) to existing MV overhead line. This type of optical cable is a means of future strengthening of the communication infrastructure of the distribution network. However, its mechanical properties are significantly different from the properties ACSR cable, due to which its installation can be problematic in terms of meeting the requirements of the PNE 33 3301 standard. In practical part, this work deals with the design of the ADSS installation on the existing MV line and the determination of its impact based on the assessment of the results of this design.
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Mokeretla, Molungoa Samuel. "Self-damping characteristics of transmission line conductors subjected to free and forced vibration." Thesis, Bloemfontein : Central University of Technology, Free State, 2011. http://hdl.handle.net/11462/15.
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Thesis (M. Tech.) - Central University of Technology, Free State, 2011The objectives of this research were to investigate and establish a procedure to determine the self-damping characteristics of transmission line conductors subjected to free and forced vibrations. The TERN and Aero-Z IEC62219-REV240609 conductor cables were the transmission line conductors that were readily available at the Vibration Research and Testing Centre (VTRC) of the University of KwaZulu-Natal (UKZN). The question to be answered was whether the self-damping characteristics of the TERN and Aero-Z IEC62219-REV240609 conductors were adequate to suppress Aeolian or wake-induced vibrations. In other words, is it necessary for external damping mechanisms to be used with these conductors? This study confirmed that the self-damping characteristics of conductors are not adequate to suppress Aeolian or wake-induced vibrations. Governing partial differential equations describing the characteristics of the catenary and parabolic cable conductors were developed to validate the experimental results. The experimental tests involved both conductors being subjected to an impulse function (a free vibration method) and also to a harmonic function (a forced vibration method). Measurements were carried out using accelerometers, and the recording equipment consisted of oscilloscopes and the PUMA system. With both the free and forced vibration methods, the damping factor of the TERN conductor was confirmed to be ζ ≤ 0.05, whereas the damping factor of the Aero-Z IEC62219-REV240609 was confirmed to be ζ ≤ 0.2. A procedure for determining the self-damping characteristics of the TERN and Aero-Z IEC62219-REV240609 conductors was developed, with the damping factor found to be ζ ≤ 0.2 for both conductors. These methods can assist in the implementation of procedural analysis of the self-damping behaviour of different types of transmission conductors and in finding the most suitable mass absorber (damper) to use in reducing the rate of failure of transmission line conductors. The results of this study can be used to improve the mathematical modelling of Aeolian and wind-induced vibrations where both self-damping properties and a mass absorber are incorporated.
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Bhattarai, Roshan. "Uprating of overhead lines." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55094/.
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This thesis establishes a rigorous procedure for overhead line uprating with guidance for calculating the increase in voltage rating that may be achieved for given configurations. It initially investigates different technical issues and conventional methods of voltage uprating of overhead transmission lines. Various issues such as clearance, insulation, pollution, transient overvoltages, surge arresters and its combinations were studied for optimised insulation coordination of voltage uprated transmission systems with reference to international standard IEC 60071 and British standard BSEN 50341. It then considers a case of existing 275kV line in 'L3' structures to analyse these issues and propose appropriate process for its possible uprating to 400kV system. In this investigation, overhead line uprating techniques used by different utilities around the world, as published in the literature were analysed. It was found that, the decision to uprate overhead lines is influenced by technical, institutional and financial issues. In this thesis, issues such as conductor air clearance, insulation electrical strength and overvoltages are investigated and taken into account to develop an appropriate methodology. For uprating overhead lines, an exemplar case study of uprating an L3, 275kV line to 400kV was used, introducing minimum structural changes to the tower. The selection of the L3 tower is made on the basis that it is not readily upratable to 400kV due to restricted air clearances it offers. This work has demonstrated that the voltage uprating of overhead transmission lines is possible with minimal modification to the existing line. In this case, the phase-to-earth clearance was found to be the critical factor which determines the level to which the voltage level of the line can be increased. Computations of overvoltages due to switching and lightning phenomena were conducted to estimate overvoltage levels and optimise the protection scheme required to minimise the required minimum electrical clearances. Employing gapless metal-oxide line surge arresters were proposed to be the most effective solution to control the overvoltages, thereby reducing the minimum phase-to-earth clearance requirements. This solution is preferred to modifying the tower structure in order to achieve the required clearance for 400kV system. The study of lightning and switching surge performances along the line under different arrester configurations was carried out so that the appropriate surge arrester configuration could be selected to maintain overvoltage levels within the targeted withstand level for the line. The extensive transient simulations performed in this work identified that, for a double circuit overhead transmission line as used on the UK system, the top-most phase conductors are prone to shielding failure lightning strikes whilst the bottom-most phase conductors are likely to be subjected to backflashover surges for the case of high tower footing resistance. The assessment of electric and magnetic field profiles of a 275kV line uprated to 400kV was computed. It showed that, the field intensities of voltage uprated lines are within the limits adopted by national and international standards and requires no additional wayleave for uprating.
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Olsen, Anders Tuhus. "Voltage Upgrading of Overhead Lines." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11218.
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Statnett wants to increase the transmission capacity in their 300 kV overhead lines by upgrading the operating voltage to 420 kV. To make this possible some modifications must be done. Insulator strings have to be elongated by two to four insulators and the air clearances must be checked. EN standards provide guidelines for how to calculate the air clearances adequately to provide required safety margins.It turns out that the formulas given by the standards provide greater safety margin than appropriate for upgraded transmission lines. By finding new proper safety margins, several towers which otherwise would have to be rebuilt to fulfill the requirements for clearances, can stay unmodified. When considering the number of towers in an average transmission line, there is obviously a great potential for saving money by putting some effort looking into proper minimum air clearances. By reduce the air clearance by approximately 10 cm, 6.5 mill. NOK were spared in a 65 km transmission line. It is therefore desirable to calculate the air clearances on the basis of smaller safety margins than described in the standard, but which is still within acceptable safety limits. In the formulas for minimum distances, the statistical withstand voltage U50%, gap-factors and altitude factors are examined for the cases of operating voltage, switching impulse and lightning impulse.Discrepancies between test results from a laboratory work conducted by STRI and calculations based on the EN standard of U50%, have been discovered. Tested U50 for switching impulses are 59 % higher than U50 from the standard. The same applies for lightning impulses where the tested value is 12 % higher than the standard. This gives reason to assume the standard to be somewhat conservative.Further, discrepancies are found between the standard EN 50341 that says that the gap factor when an insulator is present is the same as if no insulator is present, and Cigré report 72, which says that the gap factor should be corrected for the presence of insulators. Correction for insulators will lead to a lower gap factor i.e. lower break down strength along the insulator string than in the rest of the air gap. It turns out that the combination of rain and insulator string reduce the gap factor and thus, the withstand strength in the cases of switching impulses in the order of 6-13 % for V-string insulators and 20-34 % for I-string insulators and for continuous power frequency voltage in the order of 25 % for V-string insulators and 33-40 % for I-string insulators.Rain has no influence on the withstand strength of I-strings or V-strings exposed to lightning impulses.Several previous researches [1][2] shows the same tendencies of lack of correlation between U50 and gap factors when air gaps with insulator strings are exposed to lightning impulses. Thus, the gap factor is not sufficient to describe the discharge characteristics of air gaps with insulator strings exposed to lightning impulses.It is found that the air gap between phase and guy wire has approximately 7 % greater withstand strength than over the insulator string in a tower window. This additional safety margin is a desirable property in terms that the guy wires are the weakest point of a tower. This should however be verified by full-scale laboratory tests as this is mainly valid for the case of only the conductor-guy wire gap without the presence of the other air gaps that represent the tower window.
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Koutselos, Lakis Thrassyvoulos. "Galloping of overhead transmission lines." Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/844565/.
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This Thesis describes a technique for collecting, moulding and testing naturally occurring ice accretions. Faithful reproductions of the ice shapes were cast in silicone rubber from which wind tunnel models were made. They were tested using a specifically designed wind tunnel rig which measured the aerodynamic lift, drag and pitching moment of the models. From the aerodynamic data the gradients of lift, drag and pitching moment of each ice shape were calculated. The aerodynamic data were consequently used in a two-dimensional two degree of freedom theoretical aerodynamic model which included aerodynamic lift, drag, moment, ice eccentricity, conductor wake effects and the mechanical properties of the conductor. Wind tunnel tests were carried out on a specifically designed wind tunnel dynamic rig. Instabilities of the coupled vertical/torsional galloping were established. Regions of instability were also predicted using a two-dimensional theoretical conductor model. The initial theoretical analysis formed the basis upon which a more sophisticated three-dimensional finite element aeroelastic model was developed. The effects of ice and wind on the natural frequencies and the stability of the conductor were investigated. The use of galloping control devices, the pendulum detuners was also examined. Results showed that the pendulums had a stabilising effect in controlling the vertical/torsional frequency ratio of twin bundles. The vibration characteristics and the stability of quad bundles were investigated using finite elements. In this case, the pendulums shifted the torsional frequencies of the bundle to higher values close to the corresponding vertical frequencies, thus enhancing coupling and having an adverse effect on stability. Finally, limitations in the performance of the pendulum detuners were predicted.
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Jerrell, Jeffrey W. "Critical span analysis of overhead lines." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/16430.
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Roshan, Fekr Masoud. "Dynamic response of overhead transmission lines to ice shedding." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23374.
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The main objective of this research was to study dynamic effects of ice shedding on overhead transmission lines using a reliable numerical model.Overhead transmission lines are subjected to various static and dynamic loads. Ice shedding from the conductors is one of the dynamic loads occurring in cold regions. This phenomenon happens when glaze ice formed on the cables suddenly falls under certain temperature and wind conditions. In extreme instances, clashing and breakage of insulator and conductors are potential consequences of these dynamic forces. Maximum vertical cable jumps and drops in unloaded and loaded spans, and axial cable stresses are particular concerns.
The main assumptions and limitations of the proposed numerical model are discussed in detail, with appropriate stiffness, mass, damping, and ice-shedding load modelling. A nonlinear finite-element model using a commercial software (ADINA) was used to carry out simulations of 21 different ice-shedding scenarios varying the number of successive spans involved, the amount of ice accreted on the cables, different elevations of the central support, partial and sub-span ice shedding and the configuration and sequence of the shedding in adjacent spans. The analysis of the results focuses on the peak cable tensions generated, the insulator string swings and the maximum transient in-span cable displacements. Some of the results are compared with the design procedures used at Hydro-Quebec, which is based on static analysis.
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Charalampidis, Panagiotis. "Characterisation of textured insulators for overhead lines and substations." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/43818/.
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Pollution flashover constitutes the predominant parameter for the design,specification and dimensioning of high voltage outdoor insulation [1-2]. For over a quarter of a century, polymeric insulators have been used for overhead lines and substations due to their enhanced performance in highly polluted environments. This is mainly attributed to the hydrophobic properties of polymeric surfaces thatlead to a reduction of surface wetting and, thus, to a reduction of leakage current and discharge activity that could result to a flashover. However, under severe ambient conditions, discharge activity is not totally eliminated. The present investigations have demonstrated the development of dry bands and partial arcs on polymeric insulators (Chapter 3). While ‘cap and pin’ ceramic insulators - e.g. porcelain and glass - employ special anti-fog designs of increased leakage path introduced by the presence of deeper ribs, such profiles cannot be used for polymeric insulators due to moulding restrictions [1-1]. Yet, these moulding properties allow the fine texturing of the polymeric surface [1-7]. Textured insulators are a novel approach for the improvement of polymeric insulators using a surface design consisting of an array of hemispherical protuberances of various configurations and range of diameters. The objective is to reduce power dissipation (P = EJ) on the insulator surface by reducing the electric field gradient E and current density J (Chapter 2). Moreover, an increase of the longitudinal creepage path can be achieved without the need of increasing the overall length of the insulator. Where discharges do occur, the formation of parallel current paths could lead to less harmful discharges hence mitigating damage due to thermal stresses. An initial theoretical classification of the textured designs resulted to a shortlist of textured patterns that could be employed for the development of a full insulator prototype. At the next stage, these patterns were experimentally evaluated in a series of material tests in accordance to IEC-60587 inclined-plane test procedure [Chapter 5]. Rectangular silicone rubber samples with a plane surface were tested along with samples with a textured finish to assess the performance against erosion and tracking. The improvement introduced by these textured patterns in comparison with conventional non-textured samples was outstanding [2-48, 49]. The intersecting square pattern showed the best performance, hence it was chosen for the development of a full textured insulator. Conventional 11 kV silicone rubber insulators and textured insulators with the same shed profile were cast in-house using vacuum injection casting techniques. There are no international standards for the artificial testing of polymeric insulators. In this work, a proposed test procedure for non-ceramic insulators is described (Chapter 3). Clean-fog tests of conventional (Chapter 4) and textured insulators (Chapter 6), for a range of wetting and pollution severity conditions,showed that textured insulators showed an improved flashover performance that in some cases reached 26 %. Surface texturing seems to be more effective under severe conditions of wetting and pollution and when hydrophobicity is reduced, like the temporary loss of hydrophobicity observed for silicone rubber insulators in service.
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Ahmed, Yasir E. "Modelling of microshocks associated with high voltage overhead lines." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625456.
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Microshocks can be described as the unpleasant discharges experienced by people capacitively coupled to high voltage equipment once a contact is established between their finger-tips and another object at different potential. The situations in which these discharges occur are complicated and very limited research has been conducted so far in this area. The work presented in this thesis aims to enhance the understanding of the microshocks phenomenon, and in particular, focuses on exposure to microshocks by overhead transmission line workers before developing mitigation techniques to prevent the linesman from receiving microshocks or at least minimising the sensation level associated with receiving the discharges. Results of a survey that included 102 linesmen and conducted to determine the implications of different factors on the frequency and intensity of microshocks are presented. Experimental setups and activities that took place inside and outside the High Voltage laboratory to simulate the environment at which linesmen became subjected to microshocks are discussed. Initially, a simplified 2-dimensional metallic test object "Stickman", which simulates a human body, was placed in various positions relative to a lattice tower structure inside the laboratory. Measurements of induced voltages and currents on the object as a result of capacitive coupling have been made. To accurately represent the structure and shape of the human body, a 3- dimensional test object "Cylinderman" has been designed and introduced to the experimental setup replacing Stickman. Experiments have been modelled successfully using the commercial software package CDEGS (Current Distribution and Electromagnetic Interference, Grounding and Soil Structure Analysis). The software package is shown to be capable of accurately modelling simple objects made of thin conductors as well as complicated structure such as the transmission tower. Furthermore, models of realistic and complicated scenarios under which linesmen experience Microshocks have been developed. Discharge voltage waveforms recorded of human subjects experiencing microshocks have been captured successfully. By examining these waveforms it was concluded that skin impedance dictates the level of voltage drop during discharge. In addition to investigating the effectiveness of earthing the body through the footwear to prevent microshocks from occurring, experiments that lead to the identification of a novel mitigation technique are detailed. The technique aims to increase the charging capacitance to ground -represented originally by the shoe capacitance- to reduce the induce voltage on the individual. Details of a filed patent are also included.
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Zachariades, Christos. "Development of an insulating cross-arm for overhead lines." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/development-of-an-insulating-crossarm-for-overhead-lines(dee98d28-229c-46c0-a8a8-2c8a93aa6078).html.
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A novel insulating cross-arm (ICA) has been developed for new and existing overhead transmission lines of up to 400 kV. The cross-arm consists of four insulating members, end fittings, field grading devices and a nose connection for the attachment of the conductor. The two main structural elements of the assembly have a unique non-cylindrical geometry which gives them improved mechanical characteristics compared to conventional overhead line insulators. The profile for the compression insulator has been designed. After examining six profile variations, it was determined that the lateral orientation which would give the best performance would be with the flat face of the core facing upwards and tilted by 6o. Using the results obtained from performing flashover tests on a conventional 145 kV insulator, the elevation angle for the compression insulator was set to 6o. The dimensions of the compression insulator were calculated based on the assumption that the ICA would be used to uprate an OHL with L3 towers from 275 kV to 400 kV. The optimal insulator profile was determined to be an alternating profile with three different shed sizes, an arcing distance of 3083 mm and a creepage distance of 12470 mm. Electric field grading devices for the ICA were designed. For the LV end, a grading device resembling a ring which follows the general shape of the cross-section of the insulator was designed. For the HV end, an iterative process yielded two designs. First, the ‘butterfly’ grading device was a unibody piece of cast aluminium for all four ICA members. FEA simulations and tests in the laboratory showed that it could effectively control the electric field at voltages of up to 132 kV. The design was patented and the device was used on six cross-arms installed on a live line in Scotland in August 2013. Second, the ‘M-W’ grading device, was a solution made out of four components for managing the field at voltages of up to 400 kV. The device was designed to be easy to install and service, easy and cheap to manufacture and to have minimal visual impact. The compression insulator and the cross-arm assembly were subjected to a multitude of tests adapted from international standards and the Technical Specifications of National Grid. The performed tests aimed to test the electrical characteristics of the cross-arm and the quality of the materials and manufacturing process of the compression insulator. All of the tests were completed successfully except from the corona extinction test for which the appropriate equipment was not available at the time. Two trials were commissioned to examine how the cross-arm performs in a service-like environment. The snow and ice accretion patterns recorded at the mechanical trial site were used for optimising the profile of the compression insulator. The results after a year of continuous monitoring of leakage current and weather conditions at the live trial site showed that there were humidity and visibility thresholds, above 93% for the former and below 400 m for the latter, which increased the average leakage current by 15% on the tension insulators and by 20% on the compression insulators. It was found that when the longitudinal axis of the cross-arm was perpendicular to the weather the leakage current was higher because more of its surface was exposed. The performance of the novel compression insulators was found to be as good as that of the industry standard tension insulators, reaffirming the potency of the design. Finally, on-site observations showed that the ‘butterfly’ grading device could not effectively manage the electric field on the cross-arm at 400 kV, confirming the results of the FEA simulations and testing.
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Aslan, Y. "Accurate fault location on overhead distribution lines using superimposed components." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321843.
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Hussin, Mohd Fahmi. "Voltage transducer for fault monitoring on high voltage overhead lines." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/65731/.
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Overhead lines are the backbone of electrical power transmission. In most cases, the overhead line provides the best economic and practical solution for energy transmission. Nevertheless, overhead lines suffer more faults due to the vulnerability of the overhead lines to adverse weather condition, transient overvoltage and falling trees. An extensive literature review of existing condition monitoring and impulse a voltage measurement technique of overhead lines are covered in this work, and ultimately leads to the development of the proposed voltage transducer. Although conventional transducers such as voltage transformers and voltage dividers are widely used for monitoring and voltage measurement, yet they have several drawbacks in terms of their size and cost. These are the key factors that limit their widespread deployment for monitoring and measuring voltage on overhead lines and, in particular, rural areas. The proposed transducer is based on a non-contact capacitive voltage probe developed at Cardiff University. However, the proposed transducer uses a high voltage conductor rather than the ground as a measurement reference. The proposed transducer is based on a cylindrical-shaped in order to avoid sharp edges, which can initiate a partial discharge effect. Commercial numerical field computation software packages are used to assist in the development of the proposed transducer for simulation of the electric field distributions around the HV conductor and the transducer. The computed electric field magnitudes obtained on the sensing probe surface are then used for calibration of the proposed transducer. The proposed transducer is developed using low cost materials and tested in a laboratory environment with a low amplitude impulse supply using a surge generator and the corresponding output voltage amplitude obtained from the transducer was validated against a low ac voltage supply using variable output voltage source. The effects of variation in the input voltage, the integrating capacitor inserted between the HV conductor and the sensing probe and height of the transducer above ground on the output voltage amplitude are also investigated. The developed transducer is subsequently tested in field experiments using test overhead lines with low and high voltage supplies. Only a single-phase measurement setup was used in this test as there is only one voltage transducer fabricated in this work. Therefore, each phase of the overhead line was tested individually. Results obtained from the laboratory and field experiments have demonstrated the suitability of the developed transducer for measuring both ac and impulse voltages, which would be useful for fault monitoring on the high voltage overhead lines. However, the computed results obtained from the simulation demonstrated the presence of end-effects at the transducer sensing probe edges. Therefore, an improved design was proposed in this work by introducing a floating electrode between the sensing probe and the guard electrode, with the aim to reduce the fringing effects by preventing the sensing probe from sensing unwanted electric field. The physical development of this improved transducer design is yet to be initiated, and is thus proposed for future work.
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Mercer, Douglas. "Thor's hammer deflected : a history of the protection of power systems from lightning, with special reference to Queensland, 1950 to 1995 /." [St. Lucia, Qld.], 2001. http://adt.library.uq.edu.au/public/adt-QU20020712.164134/index.html.
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Langlois, Sébastien 1981. "Design of overhead transmission lines subject to localized high intensity wind." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99775.
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Wind loading considered in the design of overhead transmission lines is based on extreme values of synoptic wind, i.e. boundary layer wind originating from largescale meteorological pressure systems. Localized high intensity wind (HIW) storms such as tornadoes and downbursts are a different type of extreme wind frequently causing failures of overhead lines. This thesis covers the design aspects of overhead transmission lines when subject to localized HIW storms. A comprehensive review of the literature is included on the effects of such wind storms on lines and on mitigation measures. Furthermore, several options for the design of self-supporting transmission towers against localized HIW are discussed based on numerical simulations of several simple load cases on four examples of lattice structures.
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Mtanga, Jameson Joseph. "Dynamic modeling and vibration control of high-voltage overhead transmission lines." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5022.
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Includes abstract.Includes bibliographical references (leaves 140-144).
The problem of the dynamic behavior of overhead power transmission lines under wind and other excitations is an important one, since it allows an optimal design and positioning of vibration dampers for the cables. Excessive sway and oscillation of power lines need to be avoided, as they can lead to damage of the lines and power interruptions. The relatively high flexibility of the cables, coupled with the large spans and large sags involved, make the dynamic response of the system highly nonlinear. In this study, we numerically investigate the damped free-vibration response of systems of cables of particularly large spans (120, 200 and 400m).
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Swapnil, Muhammad Mubassir. "Computing effects of electric and magnetic fields near overhead transmission lines." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63023.
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Analysis of Electric and Magnetic Fields produced by overhead transmission lines plays a critical role prior to their construction by electrical utilities. They affect the width of the transmission corridor and terrain clearances from overhead conductors. There is substantial interest in learning about the health effects of short and long-term exposure to these fields, as induced currents and voltages from parallel lines pose a hazard to line crews working on a de-energized line.
A MATHCAD program has been developed to compute the strengths of Electric and Magnetic Fields and to determine any induction currents and/or voltages due to the coupling effect of these fields. MATHCAD is an engineering software that allows programming and development of engineering calculations using natural mathematical syntax and variables. An overview of the theory of electric and magnetic fields is also provided in this paper. This research tests a few scenarios in the MATHCAD program, and the test results are verified against EPRI (Electric Power Research Institute) and IEEE (Institute of Electrical and Electronic Engineers) guidelines to ensure consistency. The results are also compared with the safety limits published by ICNIRP (International Commission on Non-Ionizing Radiation Protection) and IEEE. We also discuss the practical use of these results, along with potential future updates to the MATHCAD program.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Savoullis, Yiannakis C. "Experimental verification and modification of a real-time ampacity program for overhead conductors." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/17840.
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Crowder, Michael R. "Assessment of devices designed to lower the incidence of avian power line strikes /." PURL image only, 2000. http://www.arlis.org/docs/vol1/62243427.pdf.
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Wells, M. Glenn. "Transient temperature distributions in overhead fiber-optic ground wires." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16885.
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Chen, Shelley L. "Programs for calculating high temperature ampacity and sag for overhead electrical conductors." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/17933.
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Habtemariam, Filmon A. "HIGH-FREQUENCY IMPEDANCE CHARACTERISTICS AND HEALTH CONDITION MONITORING OF OVERHEAD POWER LINES." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1472735633.
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Naredo, V. José Luis A. "Communication frequency response of high voltage power lines." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26725.
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Several methods for calculating the electrical phase and modal parameters of overhead transmission lines are described in this thesis; then, a graphical method for evaluating communication frequency response of delta transmission lines -based on the guidelines given by W. H. Senn [12,13,14]- is developed. The graphical method, combined with the parameters calculation methods, obviates the need of large mainframe computers for the analysis of power line carrier (PLC) systems.
A new technique for assessing coupling alternatives, based on Senn's method, is developed. The technique is applied to generate coupling recommendations; it is found that many of the current recommendations given elsewhere [21] are not reliable.
Finally, future work to be done in this field is proposed.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Roberge, Mathieu. "A study of wet snow shedding from an overhead cable /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99790.
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Wet snow accumulating and shedding from overhead transmission lines can lead to a number of serviceability, safety and mechanical reliability issues. An innovative and inexpensive method to reproduce wet snow accretions on a cable in a controlled environment is explained. Wet snow sleeves were experimentally reproduced by using this technique to study their shedding mechanism. A numerical modeling technique using nonlinear finite element analysis is proposed to evaluate the dynamic response of an overhead cable subjected to any snow-shedding scenario. A time function is associated to the mass and weight of each snow element, which enables its virtual removal from the model at the time prescribed by the user. The response of a single span of overhead ground wire subjected to total and partial snow shedding scenarios is evaluated.
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Robson, Stephen. "An integrated monitoring and communication device for use on 11 kV overhead lines." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/42930/.
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In this thesis, an integrated monitoring device for use on 11 kV overhead lines has been developed. Uniquely, the devices use an optimised form of Power Line Communication to enable a low latency communication network. It is shown that such a network is able to facilitate new and improved applications and offer tangible benefits to the network operator.
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McWhorter, Bruce Burnett. "Transient temperature distributions in short-circuited electrical conductors." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/15951.
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Hall, David Eric. "Transient thermal models for overhead current-carrying hardware." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17133.
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Lindberg, Elisabeth. "The overhead line sag dependence on weather parameters and line current." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-168528.
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As the demand for energy increases, as well as the demand for renewable energy, Vattenfall, as network owner, receives many requests to connect new wind power to the grid. The limiting factor for how much wind power that can be connected to the grid is in this case the maximum current capacity of the overhead lines that is based on a line temperature limit. The temperature limit is set to ensure a safety distance between the lines and the ground. This master thesis project is a part of a research project at Vattenfall Research and Development that is examining the possibilities of increasing the allowed current on overhead lines in order to be able to connect more wind power to the existing network. Measured data from two overhead lines in southern Sweden is analyzed and the internal relations between the measured parameters are examined. The measured parameters are overhead line sag, line temperature, ambient temperature, solar radiation, wind speed and line current. The results indicate that there is a big load margin that could be utilized to increase the maximum current as long as further work could show that low winds at line height correlates with low wind at nacelle height. The results show that the sag versus line temperature is approximately linear within the measured temperature range. This means that a real-time-monitoring system measuring the line temperature should give adequate knowledge of the line position to ensure the safety distance. A model for the line temperature as a function of insolation, current, ambient temperature and wind speed has been estimated for one of the lines. Simulations show that a sudden increase in current at a worst-case scenario would give the operators about ten minutes to react before the line reaches the temperature limit.
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NOGUEIRA, MURILO MAGALHAES. "METROLOGICAL EVALUATION OF AN OPTICAL FIBER BRAGG GRATING ACCELEROMETER: APPLICATION IN OVERHEAD TRANSMISSION LINES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7908@1.
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Linhas de transmissão de energia são estruturas
importantes em um
sistema de energia elétrica. Devido à elevada energia
transportada por essas
redes, falhas em linhas de transmissão podem ter reflexos
severos no
fornecimento aos consumidores, não raro levando a apagões
em áreas
geograficamente extensas. Entre as possíveis origens de
falhas está o
rompimento dos cabos elétricos pela fadiga provocada pela
vibração eólica. As
grandes extensões territoriais percorridas pelas linhas de
transmissão e a
variedade de climas, relevos, vegetação e condições
meteorológicas aos quais
estão submetidas dificultam qualquer trabalho de previsão
da ação do vento. A
medição da vibração permite detectar de antemão a
aproximação da falha,
porém os instrumentos convencionais dependem de
transdutores elétricos os
quais, além de exigirem uma fonte de energia (normalmente
não disponível junto
a linhas de transmissão) para seu funcionamento, sofrem
influência dos intensos
campos elétricos e magnéticos existentes em torno dos
cabos de energia. A
imunidade das fibras ópticas a campos elétricos e
magnéticos e a possibilidade
de uso de sinal de entrada de baixa potência oferecem uma
alternativa para a
criação de instrumentos de medição usando a técnica das
redes de Bragg. A
presente dissertação contribui com o desenvolvimento de um
acelerômetro
biaxial a redes de Bragg para medição de vibração em cabos
de linhas de
transmissão de energia. Além dos aspectos teóricos e
práticos envolvidos, são
discutidos os resultados de ensaios de calibração de
elevada exatidão e outros
ensaios especiais que fundamentaram a avaliação
metrológica e o
estabelecemento da eficácia do referido instrumento.Overhead transmission lines play an important role on electric systems. Due to the high energy carried through those networks, failures on overhead lines can bring severe constraints on consumers supply, occasionally taking the form of blackouts in large geographic regions. Among the reasons of such failures is the breaking of electric cables caused by the fatigue originated from cyclic bending due to aeolian vibration. The large areas covered by overhead lines and the variety of climate, relief, vegetation and meteorological conditions under which they have to operate make it difficult to foresee the impact of wind Vibration measurements would allow anticipating the failure but conventional instruments depend upon electric transducers which, besides demanding a local source of energy (usually unavailable near overhead lines), suffer the influence of the high electric and magnetic fields around the energized cables. Optical fibers immunity against environments subjected to electrical and magnetic fields and the possibility of using low energy input signals offer the alternative of creating measuring instruments using Bragg gratings technique. This Master dissertation contributes with the development of a fiber Bragg grating biaxial accelerometer for measuring the vibration of overhead transmission line cables. Besides the theoretical and practical aspects related to the subject, the results of high precision calibration tests are discussed, together with other special tests which set the basis of the metrological evaluation and the establishment of the efficacy of the instrument.
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Martinho, Lucas Blattner. "Numerical modeling of electromagnetic coupling phenomena in the vicinities of overhead power transmission lines." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-28062016-152807/.
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Les phénomènes de couplage électromagnétique entre les lignes aé- riennes de transmission d\'énergie et des structures voisines sont inévitables, surtout dans les zones densément peuplées. Les effets indésirables découlants de cette proximité sont variés, allant de l\'établissement des tensions dangereuses à l\'apparition de phénomènes de corrosion dus au courant alternatif. L\'étude de cette classe de problèmes est nécessaire pour assurer la sécurité dans les alentours de la zone d\'interaction et aussi pour préserver l\'intégrité des équipements et des dispositifs présents. Cependant, la modélisation compl ète de ce type d\'application implique la représentation tridimensionnelle de la région d\'intérêt et nécessite des méthodes numériques de calcul de champs spécifiques. Dans ces travaux, des problèmes liés à la circulation de courants électriques dans le sol (ou de couplage dit conductif) seront abordés avec la méthode des éléments finis. D\'autres problèmes résultants de la variation temporelle des champs électromagnétiques (ou de couplage dit inductif) seront aussi considérés et traités avec la méthode PEEC (Partial Element Equivalent Circuit) généralisée. Plus précisément, une condition limite particulière sur le potentiel électrique est proposée pour tronquer le domaine de calcul dans l\'analyse par éléments finis des problèmes de couplage conductif et une formulation PEEC complète pour la modélisation de problèmes de couplage inductif est présentée. Des con gurations tests de complexités croissantes sont considérées pour valider les approches précédentes. Ces travaux visent ainsi à apporter une contribution à la modélisation de cette classe de problèmes, qui tendent à devenir communs avec l\'expansion des réseaux électriques.Electromagnetic coupling phenomena between overhead power transmission lines and other nearby structures are inevitable, especially in densely populated areas. The undesired effects resulting from this proximity are manifold and range from the establishment of hazardous potentials to the outbreak of alternate current corrosion phenomena. The study of this class of problems is necessary for ensuring security in the vicinities of the interaction zone and also to preserve the integrity of the equipment and of the devices there present. However, the complete modeling of this type of application requires the three- -dimensional representation of the region of interest and needs specific numerical methods for field computation. In this work, the modeling of problems arising from the flow of electrical currents in the ground (the so-called conductive coupling) will be addressed with the finite element method. Those resulting from the time variation of the electromagnetic fields (the so-called inductive coupling) will be considered as well, and they will be treated with the generalized PEEC (Partial Element Equivalent Circuit) method. More specifically, a special boundary condition on the electric potential is proposed for truncating the computational domain in the finite element analysis of conductive coupling problems, and a complete PEEC formulation for modeling inductive coupling problems is presented. Test configurations of increasing complexities are considered for validating the foregoing approaches. These works aim to provide a contribution to the modeling of this class of problems, which tend to become common with the expansion of power grids.
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Komaragiri, Shalini Sushmitha. "A SAG monitoring device based on a cluster of code-based GPS receivers : a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=0&did=2000377771&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1277472835&clientId=28564.
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Keyhan, Hooman. "Fluid structure interaction (FSI) based wind load modeling for dynamic analysis of overhead transmission lines." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114457.
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Electricity is a crucial form of energy in our societies, and transmission lines are key elements to ensure the reliability of electric power grids. Continuity of service is the main preoccupation of electric utilities, and this continuity may be disrupted by a large variety of sources and accidents. Transmission lines, by their intrinsic topology, remain the grid components that are the most exposed to climatic sources of disruption.The most common and important source of dynamic loads on transmission lines results from wind effects on the towers and conductors. Conductors are particularly sensitive to wind effects as they are long and relatively flexible (compared to their supports) and are literally wind-catching structures in the power grid infrastructure. In cold climates, wind and ice have compounding effects on lines and give rise to the most severe design loading conditions. Therefore, accurate prediction of the wind pressure on overhead conductors is essential to conduct a reliable assessment of the line response, in terms of both electrical clearances and conductor loads transferred to supports. Spatial randomness of wind loads on overhead lines has already been addressed by stochastic analysis methods and is now taken into account in design with the use of so-called span factors. Further gains in wind load accuracy can be obtained by examining the physics of wind effects on conductors, in both non-iced and iced conditions, with improved predictions of lift and drag forces determined from fluid-structure interaction (FSI) analysis.The traditional design method to apply wind load on transmission lines is to convert the design wind speed to a static pressure through Bernoulli's equation where the pressure is proportional to the air density and the squared wind speed. In this approach the fluid-structure interaction of wind and line components is ignored: wind is considered as a quasi-static load on conductors and supports, while special instability effects due to particular wind conditions such as vortex shedding (Aeolian vibrations) and flutter (cable galloping) are accounted for separately with specific mitigation solutions if necessary.In gusty wind conditions with high turbulence intensity, conductors may experience large horizontal displacements that affect their surrounding wind flow. A physically accurate wind load evaluation on conductors is possible by computational wind-structure interaction analysis. To date, largely due to its high computational cost and the lack of experimental data to validate computational models, an advanced fluid-structure analysis framework for wind-cable interaction has not been developed. In this study a new approach based on FSI analysis to evaluate equivalent wind loads on conductors is developed. The first step in such an approach is accurate evaluation of wind pressure on conductor. For this purpose the FSI analysis is carried out in two dimensions where the detailed bare and iced conductor section geometry and surrounding air flow are modeled, considering a given incident wind speed. The conductor cross section is assumed to be supported on flexible supports to study the interaction between the conductor motion and the air flow. FSI analysis yields both the fluid and structure response. Of particular interest is the wind pressure field on the conductor section, which allows the computation of the resultant drag and lift forces. This process is repeated for several cross sections along the span and the resulting forces provide the effective span wise wind load distribution on the conductor. This wind loading is then used as input in a separate 3-D computational nonlinear dynamic analysis model to predict the line response. This dynamic analysis of the line section can be detailed to represent very realistic line sections including conductors, suspension links and supporting towers.Nos sociétés sont fortement dépendantes de l'électricité, et il ne fait pas de doute que la fonctionnalité des lignes de transport est déterminante pour assurer la fiabilité des réseaux électriques modernes. En effet, la continuité de l'approvisionnement en électricité reste la préoccupation majeure de toutes les compagnies d'électricité, et cette continuité du service peut être compromise par une multitude d'incidents ou d'accidents sur l'ensemble du réseau. Parmi toutes les sources possibles de charges dynamiques sollicitant les lignes de transport, celles provenant des effets du vent sur les pylônes et les conducteurs restent les plus fréquentes. Les conducteurs de lignes sont particulièrement vulnérables aux effets du vent car les portées sont longues et flexibles (comparé aux pylônes) et leur présence physique dans le réseau en font des structures exposées à toutes les intempéries qui peuvent survenir sur le territoire couvert. Cette vulnérabilité est encore plus grande dans les climats nordiques où les effets combinés du givrage atmosphérique et du vent créent des scénarios de charges de conception parmi les plus critiques et donc susceptibles de contrôler la conception finale des lignes. Il nous apparaît donc essentiel de comprendre la dynamique des fluides des effets du vent pour prédire avec réalisme et un degré de précision raisonnable la pression du vent exercée sur les conducteurs. Une meilleure évaluation des charges dues au vent permettrait par le fait même des prédictions plus réalistes de la réponse des lignes aux charges de vent, non seulement en terme de déplacements et dégagements électriques mais aussi en terme des charges nettes transférées aux pylônes par les conducteurs. La nature aléatoire des effets du vent sur les conducteurs a déjà fait l'objet de nombreuses études scientifiques et les méthodes d'analyse stochastique modernes permettent de cerner la question : les méthodes de conception simplifiées qui sont suggérées dans les normes et guides tiennent compte de ces effets en utilisant un coefficient de portée global qui ajuste à la baisse les efforts calculés au pylône sous des charges supposées synchrones et uniformes le long des conducteurs. Cette recherche ne concerne pas cet aspect de la question. Nous croyons que des gains de précision appréciables dans la prédiction des charges de vent sur les lignes sont possibles par une meilleure modélisation de la physique des effets du vent sur les conducteurs, dans les conditions givrées ou non, en utilisant les techniques d'analyse qui tiennent compte des interactions dynamiques fluide-structure. Ces interactions sont ignorées dans les méthodes d'analyse conventionnelles qui consistent simplement à calculer une pression statique proportionnelle à la vitesse carrée du fluide selon l'équation classique de Bernoulli. Bien sûr, les concepteurs ne négligent pas la considération des vibrations éoliennes ou du galop des conducteurs, mais ces phénomènes sont traités séparément et n'influencent pas le calcul des charges sur les pylônes. Dans cette recherche, nous nous intéressons aux conditions de vent de rafale avec grande turbulence qui caractérisent les tempêtes de vent. Ces vents forts et turbulents créent de grands déplacements des conducteurs qui modifient les conditions d'écoulement d'air. Une évaluation plus précise de ces conditions est possible par analyse computationnelle des interactions vent-conducteur.Les bases théoriques de la physique des phénomènes en présence sont connues mais aucun cadre d'application numérique n'a été proposé jusqu'à maintenant, en partie à cause des coûts numériques élevés mais aussi dû au manque de données expérimentales pouvant valider ces modèles computationnels.Nous avons développé un tel cadre d'analyse computationnelle dans cette recherche et l'avons illustré dans un cycle complet, du calcul des charges au calcul de la réponse d'une section de ligne, avec plusieurs exemples pratiques à chacune des étapes de développement
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Makhkamova, Irina. "Numerical investigations of the thermal state of overhead lines and underground cables in distribution networks." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/866/.
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As part of extensive activities on the reduction of CO2 emissions, a rapid expansion of power generation using new more fuel efficient technologies (large, medium and embedded scale with combined heat and power (CHP) projects) and renewable energy (wind, biomass, solar PV) is currently taking place in numerous European countries, including the UK. The research presented in this thesis is a part of a UK government funded project, which aims to find answers to how to accommodate increased renewable energy into the distribution network. Current ratings, which are limited by the temperature of the conductors used in the distribution network, are based on worst case scenario conditions and are conservative. The temperature limits can be lifted if one takes into consideration the dynamic changes in the surrounding environmental conditions of the conductors. Implementation of real-time thermal rating of existing power systems could result in greater installed capacities of distributed generation (DG). This research aims to provide new insights into the thermal state of overhead line conductors (OHL) and underground cables (UGC) by using Computational Fluid Dynamic methods. An algorithm consists of building the geometry of the calculation domain, meshing, choosing a model, inputting initial conditions, initiation of the calculation, and analysing results. A part of the UK power system was chosen by Scottish Power Energy Networks for monitoring essential data of OHL conductors in order to validate results of the temperatures of the conductors.
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Preston, Gary. "The location and analysis of arcing faults on overhead transmission lines using synchronised measurement technology." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/the-location-and-analysis-of-arcing-faults-on-overhead-transmission-lines-using-synchronised-measurement-technology(57595477-4361-40e2-815e-bc0b27b2eef6).html.
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Overhead transmission lines are an essential component of power systems, being the most economical means of transmitting electricity from remote sources of generation to the customer. It is, therefore, vital that they be protected and maintained in service to ensure the security of the supply to the end-user, and to protect the capital investment of the power companies. Arcing faults are a common phenomenon on power systems and being able to understand the effects of fault arcs is important for power system protection. Numerical algorithms can be developed that locate the position of and analyse faults on power systems. The aim of this thesis is to develop accurate models of arcing faults and to develop numerical algorithms that can operate successfully on different power system topologies under various fault conditions. Comprehensive literature reviews have been completed the areas of electrical arcs and fault location algorithms. Existing arc models are investigated and new alternative methods of simulating them are proposed. A new method of modelling the elongation of secondary arcs is devised in this thesis and verified using real arc data. A new ‘AirArc’ model for use in fault simulations is proposed and its accuracy is verified by comparison with the behaviour of a real arc. Three new numerical algorithms, developed for this thesis, for fault location and analysis, based upon the synchronised sampling of voltage and current data at both ends of the line, are derived and their accuracy tested for a number of different network topologies and fault scenarios. Finally, there is a chapter summarising the work completed for this thesis, drawing conclusions from that work and suggesting further work that could be undertaken in the future.
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Crnojacki, Zorica. "Extra high voltage transmission corridor siting : technical, public, institutional and regulatory considerations /." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10032007-171749/.
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Ghaderi, Abbas. "Self-powered system for the detection and location of faulted insulators in overhead distribution power lines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Post insulators as the weakest component of transmission lines, are highly exposed to breakdown. Insulators breakdown leads to outage and economic loss for transmission companies. Faulted post insulator detection and location is very important to minimum duration of outage. Depending on type of post insulators types, they can be detected in case of breakdown. Silicon rubber post insulators as new generation of insulators, have better insulation characteristics compare to others. Away from all of its advantages, detection and location of broken ones are difficult for system operator due to no external damage. In this thesis design of a self-powered system to detect the broken silicon rubber post insulator has been pursued. An innovative optical effect triggered by self-powered system has been deployed to detect faulted post insulator.
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Bibby, Ian Paul. "Theoretical database for the prediction of rime-ice and wet-snow overload on overhead transmission lines." Thesis, University of Hull, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322337.
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Qi, Gang. "Computational modeling for stress analysis of overhead transmission line stranded conductors under design and fretting fatigue conditions." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121122.
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While great efforts have been made in the electrical utility industry to engineer various stranded conductors with enhanced strength and vibrational characteristics, research devoted to understanding the complex mechanical behavior of complete conductors has been scarce, especially from a computational mechanics perspective. In the meanwhile, the long-lasting problem of conductor fretting fatigue becomes increasingly critical for overhead line design and maintenance, especially with the world-wide aging of electrical transmission grids. Aging of conductors contributes to significant degradation of their local fatigue strength, leading to drastic reduction of their service life. However, the complex mechanical response of stranded conductors cannot be well predicted by either experimental testing or simplified theoretical models, owing to the physical complexity introduced by their multi-layer stranded geometry, nonlinear material properties, substantial frictions among the wires and between the wires and hardware clamping systems, as well as the comprehensive contact interactions amongst their components. Simplified beam models and coarse 3-D models of earlier computational studies also fail to calculate the accurate stress variations inside a conductor strand and capture the stress gradients near the contact interfaces. Moreover, the estimations of fretting fatigue life are very dependent on the high accuracy of the stress predictions in the conductor wires. Therefore, reliable high-fidelity computational models have been long expected for a better understanding of the contact damage of transmission line conductors under both design and fretting fatigue conditions. The main objective of this thesis is to study the complex stress states and relevant influencing factors of stranded electrical conductors, using finite element analysis approaches. The research was carried out in three stages. First of all, a study focused on the finite element (FE) modeling of an optical ground wire (OPGW) cable strand for its detailed stress analysis. A refined 3-D FE model including all essential nonlinear characteristics was successfully constructed. As a result, a high-fidelity physics-based macroscopic modeling methodology was developed for detailed and accurate computational stress analysis of stranded conductors. A 795 kcmil Drake ACSR conductor was then selected as a benchmark conductor to investigate the tensile strength and critical stress states of a complete conductor under extreme design conditions. Furthermore, a sensitivity study explored the relative importance of friction effects among conductor wires on the mechanical response.A large scale 3-D FE stress analysis model with comprehensive nonlinearities was developed and implemented to simulate an actual ACSR fretting fatigue test. The computational results showed good agreement with some experimental measurements and field observations reported in the open literature. Based on the accurate stress analysis, a practical multi-axial fatigue lifing methodology was developed to estimate local fretting fatigue strength of electrical conductors. Subsequently, a parametric study was performed to examine the influence of fretting amplitudes on the mechanical response of the conductor-clamp system.In conclusion, this research shows the reliability and significance of using reliable FE modeling in predicting the complex response of stranded conductors, which has contributed to fill some of the current knowledge gaps. Furthermore, the computational modeling and lifing approaches developed in this thesis provide a different perspective from existing practices and may become a starting block of further exploration of the mechanisms of conductor fretting fatigue and future development of improved fatigue lifing methods for the increasingly aging overhead transmission line conductors.Malgré les efforts déployés par l'industrie des lignes de transport d'électricité pour la conception de conducteurs toronnés de haute résistance mécanique, la recherche dédiée à la compréhension physique du comportement mécanique des conducteurs s'est faite plus rare, surtout du point de vue de la mécanique computationnelle. Le problème du vieillissement des conducteurs de lignes aériennes à haute tension, en particulier celui de l'usure en fatigue des brins et torons, n'est toujours pas complètement compris ni donc résolu. Le vieillissement des conducteurs se manifeste par une dégradation importante de leur résistance locale à l'usure en fatigue, réduisant par le fait même leur vie utile et la robustesse mécanique de l'ensemble de la ligne. Il faut reconnaître que les études expérimentales et les modèles théoriques simplifiés ne peuvent pas prédire le comportement mécanique détaillé des conducteurs toronnés à cause de la complexité physique de ces câbles: torons et brins multicouches, matériaux inélastiques non-linéaires, effets des frictions substantielles entre les brins, torons et les surfaces des accessoires d'attache, ainsi que les interactions de contact entre ces éléments.Les travaux rapportés dans la thèse procèdent en trois étapes principales, décrites ci-après. La première partie consiste à préparer un modèle de section de câble de garde à fibre optique (CGFO) de construction complexe et d'en faire l'analyse détaillée sous déplacement axial contrôlé. Cette étape a servi à établir les bases de la méthodologie proposée, lesquelles sont discutées de manière exhaustive. La deuxième partie de la recherche porte sur la modélisation raffinée du conducteur de ligne ACSR 795 kcmil qui porte le nom de code « Drake », sélectionné comme cas de référence pour étudier la résistance en traction et les états de contraintes complexes du conducteur sous des conditions de conception extrêmes de conception. sensibilité a également exploré l'importance relative des effets frictionnels entre les brins du câble sur les contraintes calculées par le modèle. Finalement, un modèle détaillé 3-D est créé pour simuler les conditions précises d'un essai typique de fatigue en flexion pour le conducteur « Drake » jumelé à une pince de suspension. Le modèle retient toutes les non-linéarités du problème d'un point de vue mécanique. l'auteur suggère une méthode pratique pour évaluer la résistance locale en fatigue multiaxiale des conducteurs du type ACSR au droit des points de contact des pinces de suspension. Cette méthode est relativement simple d'application (une fois les analyses de contraintes disponibles) et donne des résultats en accord avec les valeurs recommandées par les manufacturiers pour le câble « Drake ». Par la suite, une étude paramétrique est faite pour vérifier l'influence de l'amplitude des mouvements de glissement sur les états de contraintes déterminés dans le conducteur dans la région de contact avec la pince sous l'effet d'un cycle complet de chargement flexionnel. En conclusion, cette recherche démontre la faisabilité et la pertinence de l'usage des méthodes computationnelles avancées pour l'analyse des contraintes d'un problème complexe comme celui des conducteurs toronnés multicouches. La méthodologie de construction des modèles est une contribution scientifique importante qui permet d'améliorer notre compréhension du comportement mécanique des conducteurs sous charges extrêmes ou dans des conditions de fatigue flexionnelle. La méthode proposée pour l'estimation de la résistance à l'usure en fatigue est également utile pour l'industrie des lignes de transport et pour les manufacturiers de câbles et il est envisageable que cette recherche servira de tremplins à plusieurs autres études computationnelles pertinentes sur les conducteurs de lignes afin d'améliorer leur fiabilité et leur robustesse mécanique.
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Gerini, Francesco. "Locating lightning strikes and flashovers along overhead power transmission lines using electromagnetic time reversal based similarity characteristics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Questo lavoro di tesi si pone l’obiettivo di analizzare, verificare e implementare un nuovo metodo per la localizzazione di guasti in rete e fulminazioni basato sulla teoria ”Electromagnetic Time Reversal”. L’applicabilità della teoria è inizialmente discussa, successivamente utilizzando le classiche equazioni delle linee e le basi della teoria EMTR viene proposta una soluzione analitica per la localizzazione del guasto e/o della fulminazione. La accuratezza del metodo utilizzato viene discussa in relazione al numero di misure necessarie alla localizzazione mettendo in evidenza pro e contro rispetto alle tecniche attuali. Viene in seguito presentato un secondo metodo di localizzazione anch’esso basato sulla teoria EMTR ma non ancora verificato su un grande numero di casi, chiamato Similarity Property Method. Utilizzando il software EMTP per l’analisi di transitori e con l’ausilio di MatLab entrambi i metodi vengono testati su diverse tipologie di reti e con diverse condizioni al contorno. Infine una analisi conclusiva viene proposta, indicando come e se i metodi presentati possono essere da considerare migliorativi delle attuali tecniche di localizzazione di guasti e/o fulminazioni.
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Fonseca, Marco Filipe Matos da. "Integrating wind generation in the distribution network." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8187.
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Energias Renováveis – Conversão Eléctrica e Utilização SustentáveisOne of the current challenges the electricity grid has is to actively connect future generation to its network without the need to fully reinforce it. This dissertation will study the use of dynamic ratings on overhead lines to increase its capacity and thus defer major investment on infrastructure reinforcement. The amount of current an overhead line can withstand in a given time is defined by the distance towards the ground, which is proportional to the conductor´s temperature, which is given by a static rating stated in the P27 standard – “Current Rating Guide for High Voltage Overhead Lines Operating in the UK Distribution System”. This rating changes from season to season and depends on specific values for ambient temperature, wind speed, wind direction and the probability that in a year the conductor exceeds its design temperature. This standard is seen as being very restrictive and a limiting factor on overhead line capacity for both future generation connections and demand. Wind speed and direction are extremely important on the cooling of overhead lines and in times of strong winds the conductor cools down, allowing extra amount of current to flow through it. By using real time weather data, it´s possible to obtain the maximum current that can flow in an overhead line for a specific operating temperature and assess the amount of headroom possible given by the difference between the static ratings and the new dynamic ratings is assessed. A view on the extra amount of energy produced, as well as CO2 emission savings and profit will also be presented, giving a practical result by applying dynamic ratings.
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Du, Toit Nicolaas Serdyn. "Calibration of UV-sensitive camera for corona detection." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/1016.
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Coneybeer, Robert T. "Transient thermal models for substation transmission components." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17686.
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Najafi, Syed Ahmed Ali. "Energy Harvesting From Overhead Transmission Line Magnetic Fields." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1548448189459464.
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van, Rensburg Karel Jensen. "Analysis of arcing faults on distribution lines for protection and monitoring." Queensland University of Technology, 2003. http://eprints.qut.edu.au/15800/.
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This thesis describes an investigation into the influences of arcing and conductor deflection due to magnetic forces on the accuracy of fault locator algorithms in electrical distribution networks. The work also explores the possibilities of using the properties of an arc to identify two specific types of faults that may occur on an overhead distribution line. A new technique using the convolution operator is introduced for deriving differential equation algorithms. The first algorithm was derived by estimating the voltage as an array of impulse functions while the second algorithm was derived using a piecewise linear voltage signal. These algorithms were tested on a simulated single-phase circuit using a PI-model line. It was shown that the second algorithm gave identical results as the existing dynamic integration operator type algorithm. The first algorithm used a transformation to a three-phase circuit that did not require any matrix calculations as an equivalent sequence component circuit is utilised for a single-phase to ground fault. A simulated arc was used to test the influence of the non-linearity of an arc on the accuracy of this algorithm. The simulations showed that the variation in the resistance due to arcing causes large oscillations of the algorithm output and a 40th order mean filter was used to increase the accuracy and stability of the algorithm. The same tests were performed on a previously developed fault locator algorithm that includes a square-wave power frequency proximation of the fault arc. This algorithm gave more accurate and stable results even with large arc length variations. During phase-to-phase fault conditions, two opposing magnetic fields force the conductors outwards away from each other and this movement causes a change in the total inductance of the line. A three dimensional finite element line model based on standard wave equations but incorporating magnetic forces was used to evaluate this phenomenon. The results show that appreciable errors in the distance estimations can be expected especially on poorly tensioned di stribution lines.New techniques were also explored that are based on identification of the fault arc. Two methods were successfully tested on simulated networks to identify a breakingconductor. The methods are based on the rate of increase in arc length during the breaking of the conductor. The first method uses arc voltage increase as the basis of the detection while the second method make use of the increase in the non-linearity of the network resistance to identify a breaking conductor. An unsuccessful attempt was made to identifying conductor clashing caused by high winds: it was found that too many parameters influence the separation speed of the two conductors. No unique characteristic could be found to identify the conductor clashing using the speed of conductor separation. The existing algorithm was also used to estimate the voltage in a distribution network during a fault for power quality monitoring purposes.
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Watson, Cody. "Modeling of pressure transients in fuel injection lines." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16869.
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Sims, Sally Caroline. "The impact of high voltage overhead power lines on the value of residential property in the United Kingdom." Thesis, Oxford Brookes University, 2004. https://radar.brookes.ac.uk/radar/items/47d4ec9e-e187-4218-b8da-5371c528a5da/1.
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This thesis investigates the impact of electricity distribution equipment on the value of residential units in the UK. This is a complex task, due to the potential influence on the market from the publics' perception of a perceived link between living in close proximity to high voltage overhead power lines (HVOTLs) and a number of adverse health effects. A review of the literature revealed that no previous studies had been undertaken within the UK to establish the impact of HVOTLs on house prices and as such, identified a gap in knowledge within the UK and provided a focus for this thesis. Due to a lack of available transaction data in England, investigating the impact on house price relies entirely on the use of qualitative research methods. Therefore to test the accuracy of the results from the perceptual study, a benchmark was developed using transaction data obtained from a residential housing estate in Blackwood, Scotland where a HYOTL was present. The thesis begins with an overview of the current planning and development controls relating to the siting of electricity distribution equipment and the subsequent development of land near HYOTLs. A critical review of the literature is presented which, due to the perceived relationship between living near HVOTLs and a health risk, includes literature on other related areas, for instance, property stigma, risk analysis and scientific and epidemiological studies on the possible health effects. ' A multimethod approach is adopted towards data gathering, using both qualitative and quantitative research paradigms. Buyers' and valuers' perceptions of the impact of a HYOTL on value are obtained using postal surveys and interviews. Additional information is gathered from the electricity utilities, residential developers and government planning departments. Using a case study approach and a hedonic pricing methodology (to enable the relationship between a HYOTL and house price to be explored), selling price data and asking price data from three locations were gathered and analysed. Regression analysis established that a INOTL near a residential unit does have an impact on house price, although this impact is not always negative. The results from three case studies, the opinion surveys and the interviews are compared, indicating that opinion surveys may result in an underestimation of the impact of a HYOTL on selling price and, by contrast, appraisers may overestimate the negative impact of HVOTLs on asking price when marketing a house. The results suggest reliance on one method may prove misleading and therefore the use of a multimethod approach towards data collection may improve the reliability of findings.
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Lawson, Allan Brett. "Environmental impact assessment in the routing of high voltage overhead transmission lines : theory and practice in South Africa." Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/16103.
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Includes bibliographies.This study resulted from a perception held by the author that more attention is afforded to complying with the procedural elements of Environmental Impact Assessment (EIA) in South Africa, than to ensuring the validity of its technical content. The routing of high voltage overhead transmission lines provides a relevant field of study in which to address this perception. An initial literature review to contextualise the perceived problem showed that the questionable validity of the technical content of EIA was one of six shortcomings identified. To address the problem, an inductive approach was adopted to focus on the interpretation and prediction activities of EIA and two propositions, stated as research questions for discussion, were developed. These referred to the theoretical question of whether methods are specified for high voltage overhead transmission line EIAs, and to the practical question of whether the environmental impacts that are known to result from transmission line projects are effectively addressed in such EIAs in South Africa. Investigating these questions provides insights into whether the technical content of transmission line EIA is sufficiently rigorous in South Africa. The method of study takes the form of a sequentially more focused examination of the literature on EIA, from the strategic level, to the sectoral level and culminating at the project level. EIA methods specified for linear developments were identified at the sectoral level, while at the project level the known environmental impacts that result from high voltage overhead transmission lines were determined. A theoretical background was compiled in this way, which allowed for comparison with the practice as determined from benchmark and case study Environmental Impact Reports (EIRs).