Flashover problems caused by ice build up on insulators

Farzaneh, M.; Kiernicki, J.

doi:10.1109/57.372510

Cited by 153 publications

(120 citation statements)

References 35 publications

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“…Nos paramètres expérimentaux ont été choisis en tenant compte des résultats obtenus des études précédentes dans le même domaine [7,16,17,71,72]. De ces investigations, on pouvait tirer que la distance inter-électrodes, le rayon de courbure des électrodes, la température de test et la conductivité du canal inter-électrodes étaient des paramètres très influents.…”

Section: Iii4 Paramètres Expérimentauxunclassified

“…Elles ont été choisies en accord avec celles obtenues sur les sites naturels de givre [14,73]. Ces valeurs ayant déjà servi dans les investigations précédentes [7,16,17,74], il parait tout à fait naturel de les utiliser à nouveau dans nos tests pour des raisons de comparaison et d'analyse. Pour obtenir de l'eau avec une certaine conductivité, du chlorure de sodium (NaCl) est progressivement ajouté dans de l'eau dé-ionisée jusqu'à atteindre la valeur désirée.…”

Section: Iii41 Distance Inter-électrodes Et Rayon De Courbure De L'unclassified

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Initiation et développement des décharges couronnes sur une surface de glace /

Ndiaye¹

2003

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Insulator surfaces exposed to tangential electric fields frequently constitute the weakest part of high voltage systems. Although a large body of experimental data on surface flashover has been accumulated and in spite of the fact that the breakdown of gas gaps has become a rather well understood phenomenon, a comprehensive physical understanding of ice surface discharge has not yet been achieved.This project aimed at investigating further, with new measurements, the basic physical processes of ice surface discharge inception and propagation. The better understanding of these processes will enable to design equipments more adapted to cold regions weather and to increase the power networks reliability in icing atmospheric conditions. Ultra high-speed photographic techniques have been applied to observe the first nanoseconds of visible discharge initiation and development on the ice surface. Since outdoors insulators have a very complex shape, a simplified physical model of rod-plane configuration has been used. The electric field inception of streamers, their propagation speed and the axial distance of critical volume have been studied.The results have been derived from Peek's experimental law and compared with those obtained in air gaps. They showed that the presence of ice surface could modify considerably corona streamers inception and propagation parameters. Several hypotheses that could be related to the ice surface discharge inception and propagation have been retained. It's possible that the interaction between the discharge and the ice surface lets occur others mechanisms not existing in air case. Charges accretion hypothesis on the ice surface has seemed to be very pertinent. The presence of these surface charges can modify considerably the local field distribution and it distorts the discharge inception and propagation parameters. Several mechanisms related to the surface charge accretion processes have also been identified. IV REMERCIEMENTSCe projet de recherche a été réalisé dans le cadre des activités de la Chaire Industrielle CRSNG/Hydro-Québec/UQAC, sur le Givrage Atmosphérique des Équipements des Réseaux Électriques (CIGELE). Je tiens alors à remercier avec ma plus profonde gratitude le Professeur Masoud Farzaneh, le titulaire de cette chaire, pour m'avoir accueilli au sein de son équipe de chercheurs et pour avoir supervisé mes travaux en qualité de directeur de recherche.Je tiens aussi à témoigner toute ma reconnaissance au Docteur Issouf Fofana, mon co-directeur de mémoire, qui a su mettre à mon égard toute sa disponibilité et son aide sans jamais arrêter de m'encourager. Je dédie ce modeste travailA mon cher père qui m'a quitté alors qu'il éclairait ma route vers le devenir qu'il m'avait prédit A ma mère, plus que jamais irremplaçable, pour son amour, ses conseils, ses encouragements et ses prières.Et à mes frères, pour la confiance qu'ils m'ont toujours témoignée.

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Section: Iii4 Paramètres Expérimentauxunclassified

Section: Iii41 Distance Inter-électrodes Et Rayon De Courbure De L'unclassified

Initiation et développement des décharges couronnes sur une surface de glace /

Ndiaye¹

2003

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“…Incidents caused by flashover on ice-covered insulators have been reported by various authors from different countries [2][3][4].…”

Section: Overviewmentioning

confidence: 99%

“…When the length of arc reaches about 60% of inter-electrode distance, the speed of arc propagation will increase rapidly, leading to flashover of the whole insulator string [2].…”

Section: Overviewmentioning

confidence: 99%

Spectroscopic investigation of arc over an ice surface /

Nekahi¹

2011

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Ice accumulation on insulators of overhead transmission lines and substations has been recognized as a major problem which may cause insulator flashover and power outages. This phenomenon starts with corona discharge activity and continues with the formation of partial arcs which may result in flashover. Due to the complexity of the process, resulting from surface interaction of discharge with the water film on the ice surface, is not yet fully understood. As for any other type of discharge, the knowledge of some parameters such as temperature and concentration of different species is necessary in order to describe the mechanisms involved. Moreover, to develop mathematical models for discharge propagation, an estimation of discharge channel conductivity is necessary. The current flows through this conductive channel and supplies the energy needed to sustain the ionization activity inside the channel. The conductivity of discharge channel is directly related to its temperature, which illustrates the need for discharge temperature measurements. Up to now, for an arc over an ice surface the temperature has been assumed to have a constant value of 5,000 K, but without any experimental support.The existence of Local Thermodynamic Equilibrium (LTE) is another important aspect for proposing theories and models, but this has not yet been verified for flashover on icecovered insulators. The verification of LTE condition requires information about temperature and concentration of different species, electron density and ionization level.The objective of this research is to augment our knowledge of flashover on icecovered insulators by measuring and calculating several important discharge column parameters. Measurement of rotational and excitation temperatures, and electron density during arc propagation are the first steps. The effect of discharge current, voltage type and polarity on the variation of the mentioned arc parameters should be also studied.Based on these data, the LTE condition could be examined.Spectroscopic plasma diagnostic is a non-destructive test method used to achieve the stated objectives. The emitted light from an arc over an ice surface was transmitted to a spectrometer. The time-resolved recorded spectra of arc were used to study the nature and concentration of ionized species. The gas and electron temperatures and electron densities were also measured using Boltzmann and Stark broadening methods.Measured rotational temperatures were found to vary from 4,000 K to 6,500 K, while the current increased from 200 mA to 700 mA during the discharge propagation. It was observed that under similar experimental conditions, the arc current intensity of DC+ arcs were hotter than that of DC-. Moreover, arc temperatures under AC voltage were lower than those of DC+, and close to that of DC-. The excitation temperature was measured at about 9,000 K and does not vary significantly with discharge current. As current increases, electron densities increased as well. For currents ranging from 200 mA to 700 mA, ...

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“…Since 1950s, many countries in the world, China included, have researched on icing of transmission lines and achieved many important results [1][2][3][4][5][6][7]. But so far, icing mechanism on transmission lines and insulator strings, flashover characteristics of ice-covered insulator strings and many other problems are still far from resolved [8][9][10][11][12][13][14][15][16], and there is almost no understand about the icing reasons of power grid under microtopography and micrometeorology conditions [9].…”

Section: Introductionmentioning

confidence: 99%

Atmospheric icing status and type of southwest China networks

Li¹,

Zhang²,

Zhou

et al. 2016

MATEC Web Conf.

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Abstract. Transmission line disconnection, tower collapse and insulator flashover caused by icing seriously threaten power system security. Ice type and state of transmission lines, which vary a lot with terrain and climate, in typical areas such as Daqing-ridge, Yak Mountain and Erlang Mountain in Sichuan Province in South China were investigated in this paper. It is shown that mixed-phase ice with obvious layered structure, low density, strong adhesive force and windward-side growth is the main type of ice threatening the security of transmission lines and insulators. There is more ice on the ends of insulators than other areas in severe cases, where all sheds of the insulator is bridged by ice. Besides, temperature, humidity and precipitation intensity are main factors influencing the icing process. As a result, terrain and climate play a leading role in determination of icing type and severity.

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Flashover problems caused by ice build up on insulators

Cited by 153 publications

References 35 publications

Initiation et développement des décharges couronnes sur une surface de glace /

Initiation et développement des décharges couronnes sur une surface de glace /

Spectroscopic investigation of arc over an ice surface /

Atmospheric icing status and type of southwest China networks

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