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ABSTRACT: This paper attempts to apply artificial intelligent techniques in high voltage applications and especially to estimate the critical flashover voltage (FOV) for polluted insulators, using experimental measurements carried out in an insulator test station according to the IEC norm and a mathematical model based on the characteristics of the insulator: the diameter, the height, the creepage distance, the form factor and the equivalent salt deposit density and estimates the critical flashover voltage. Two types of artificial neural networks (ANNs) are designed to establish a nonlinear model between the above mentioned characteristics and the critical flashover voltage. The ANNs models, algorithms, and tools have been developed using the software package Matlab. The obtained results are promising and insure that artificial intelligent techniques can estimate the critical flashover voltage for new designed insulators with different operating conditions and constitute an indispensable models that can be used in field simulations of various parameters for polluted insulators. Further comparative analysis of the estimated results with the measured data collected from the site measurement amply demonstrate the effectiveness of the use of artificial intelligent techniques for modeling (ANNs) of FOV.
Electrical and Electronics Engineering, 2009. ELECO 2009. International Conference on; 12/2009
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ABSTRACT: The paper comprises an experimental investigation into the influence of AC conditions, in order to maintain an arc burning on a dielectric surface. The present work proposes a regression model which is based on re-ignition conditions as an important factor in determining the flashover criterion of a polluted insulator under AC voltage. The measuring method and results of the re-ignition constants are presented. Comparison of computed results with the results obtained from other models, as well as experiments, indicates a good agreement.
Electrical Insulation and Dielectric Phenomena, 2004. CEIDP '04. 2004 Annual Report Conference on; 11/2004
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ABSTRACT: Our work consists to develop a computer code based on charge simulation method and to apply it for the calculation of the electrostatic field in important and complex geometries containing several homogeneous mediums. In particular calculation of the field with axial symmetry, the analytical example is a geometry stem plan, the plan representing a heterogeneous ground of variable conductivity.
Solid Dielectrics, 2004. ICSD 2004. Proceedings of the 2004 IEEE International Conference on; 08/2004
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ABSTRACT: Our work treat the effect of the temperature on the appearance of partial discharges in high voltage cables. We modelize the heterogeneous insulator of the cable using finite difference method. The numerical treatment is carried out in bidimensional due to the observed symmetry in the cavities. We simulate regions of weak concentration to an insulator containing one cavity, this is justified by the absence of interactions between cavities. The regions of great concentrations are simulated to an insulator, which contain two cavities in mutual interactions. Once the two cavities are in contact, we speak then of a complex defect called "bi-vacuole". The physical proprieties two simulate are the electrical field and the temperature. We present the results of computation obtained by an established program, this result show that the partial discharge is occurred in cavities of small diameters in regions either near the core or the wrapping. The mutual interaction between cavities contributes much the apparition of the partial discharges.
Electrical Insulation and Dielectric Phenomena, 2003. Annual Report. Conference on; 11/2003
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ABSTRACT: During electric flashover process its difficult to determine the real values of ions mobility, because we did not known the nature of different ions ejected forward the leader of the discharge. Using results of time to flashover measurements against applied voltage which carried out under AC with the experimental set up. In this paper the regression method is used to model accurately the relationship between flashover time and insulators parameters in order to calculate the ions mobility. Moreover the results obtained are discussed. The present study indicates that the different values of ions mobility are a good concordance between this model and those obtained in humid air and water steam.
Electrical Insulation and Dielectric Phenomena, 2003. Annual Report. Conference on; 11/2003
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ABSTRACT: Our work treat the effect of the temperature on the appearance of partial discharges in high voltage cables. We modelize the heterogeneous insulator of the cable using finite difference method. The numerical treatment is carried out in bidimensional due to the observed symmetry in the cavities. We simulate regions of weak concentration to an insulator containing one cavity, this is justified by the absence of interactions between cavities. The regions of great concentrations are simulated to an insulator, which contain two cavities in mutual interactions. Once the two cavities are in contact, we speak then of a complex defect called "bivacuole". The physical proprieties two simulate are the electrical field and the temperature. We present the results of computation obtained by an established program, this result show that the partial discharge is occurred in cavities of small diameters in regions either near the core or the wrapping. The mutual interaction between cavities contributes much the apparition of the partial discharges.
Power Tech Conference Proceedings, 2003 IEEE Bologna; 07/2003
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ABSTRACT: The concept of the estimated intensity of the electrical current flowing in the electrolyte enables one to check the advancement of the leader of the discharge according to time. We observed the extension of a discharge on an electrolyte surface by using an original set-up permitting simultaneous measurements of optical and electrical parameters on the same flashover in different points of the discharge path. The resistance per unit length of the conductive film was varied in the range 2 kΩ/cm to 10 kΩ/cm. Experimental results suggest that on the first half of the course that the discharge nearly propagates with a constant instantaneous velocity. It then accelerates its progression on the second half with discontinuities capable to be assigned to progressions by jumps characterizing a change of mechanism of propagating discharge. Our results have been validated by comparison with those published in the literature, which they confirm and often refine. The results bring to the fore the presence, ahead of the principal discharge, of a photoionization zone in which the development can occur of the streamers serving as precursors to its extension.
Electrical Insulation, 2002. Conference Record of the 2002 IEEE International Symposium on; 05/2002
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ABSTRACT: Most previous works treat improving the flashover resistance of electrical equipment energized in polluted environments under a global aspect and search for the critical conditions in which the discharge will be burned during its elongation on models often brought back to only one dimension. The values of electric field calculated to the leader of the discharge are very lower to the dielectric rigidity of the surrounding air and don't permit to explain the lengthening of the discharge. In this work, we develop a survey of the distribution of the electric field in the inter-electrode space and to the neighborhood of the leader of the discharge while taking into account the real geometry of the laboratory model. These electric parameters have been compared experimentally to those recorded on this experimental device. Our results justify the presence forward of the main discharge of a zone of photo-ionization in which can develop the streamers serving precursors to its extension.
Electrical Insulation and Dielectric Phenomena, 2002 Annual Report Conference on; 02/2002
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ABSTRACT: This work concerns the modeling of electric flashover on polluted insulators. We return the results of the survey of a discharge that established on slightly conductive surfaces under DC. To raise the previous model fragility, we proposed a new mathematical electric equation development governing the discharges parallel in view of a dynamic survey. Electric parameters of current and potential recorded in different points of the path of the discharge have been determined. To validate the results, a comparison with the similar parameters recorded on an experimental model has been made, and the acceptable agreement reinforces our given hypotheses and support our survey.
Electrical Insulation and Dielectric Phenomena, 2002 Annual Report Conference on; 02/2002
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ABSTRACT: This paper presents some results serving in modeling of flashover
of polluted insulators, and also in the validity test of extension
mechanisms of discharge. A flashover has been established on a
laboratory model simulating a polluted insulator and has been read
electrical and optical parameters in different points of the discharge
path. Inspired by the previous works, optical results shown weak light
intensity of the discharge comparable to streamers; these streamers
could be used as forerunners of discharges that end to a flashover. This
subject, besides its scientific relevance, is likely to have economic
effects in the field of electrical energy distribution networks
equipment
Electrical Insulating Materials, 2001. (ISEIM 2001). Proceedings of 2001 International Symposium on; 02/2001
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ABSTRACT: We observed the extension of a discharge on an electrolyte surface either with an electronic camera or by using an original set-up permitting simultaneous measurements of optical and electrical parameters on the same flashover. The corresponding results are presented here. They show two zones of different luminosity. The development of them are very different. Zone 2, the darker of the two, is nearer the ground electrode, whereas the zone 1, the brighter one, is behind it starting from the HV electrode and has a better defined outline. At the onset of the flashover in its first phase, the zone 2 spreads faster than the zone 1. Later, in a shorter second phase, the zone 1 develops more quickly and progressively overruns the zone 2. Thereafter, suddenly the flashover is completed. We comment on these results and suggest an explanation.
Electrical Insulation and Dielectric Phenomena, 2000 Annual Report Conference on; 11/2000
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ABSTRACT: Solid extruded polymeric materials such as crosslinked polyethylene (XLPE) are widely used in the electrical insulation of underground high voltage power transmission cables. However, the electric strength of the high voltage cable is affected by the presence of cavities (voids) in the insulating part. During service, when the insulation is subjected to electrical, mechanical and thermal stresses, these cavities may create a larger discontinuous region. As embedded gases and XLPE have different permittivities (respectly 1 and 2.3), the potential distribution is not equally distributed and may exceed the breakdown voltage of the gas. On the other hand, under high voltage operating conditions, trapped or low mobility electrically charged species within the bulk can give rise to space charge build up. This paper treats the combined effect of space charge and cavities on the electric field, potential and temperature distribution within solid insulation. The values of their magnitudes in cavities are calculated, enabling us to envisage if partial discharges appear in these weak parts. The model is a 3D stationary linear FEMLAB model in electrostatics and heat transfer by conduction mode.
