Study of the Development of Positive Streamers Along an Ice Surface

Ndiaye, Ibrahima; Farzaneh, M.; Fofana, I.

doi:10.1109/tdei.2007.4401226

Cited by 26 publications

(16 citation statements)

References 24 publications

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“…The peak temperatures were in the 28,000-31,000 K range. He used the Stark-broadened half-width of the H a line and calculated an electron density in the order of 8x10 17 cm" 3 in the first 5 (asec, decreasing to l-1.5xlO 17 cm" 3 at 25 ]xs. They also performed the same study on long air gaps [49], [54].…”

Section: Arc Discharge Temperature and Electron Density Measurementmentioning

confidence: 99%

“…A large number of experimental investigations and theoretical studies on the subject of ice accretion on outdoor insulators have been carried out in several laboratories [13][14][15][16][17]. A good survey of the related literature is found in [18].…”

Section: Introductionmentioning

confidence: 99%

“…For currents ranging from 200 mA to 700 mA, electron densities increased from 1 to 2 xio 17 cm' 3 . Electron densities increased up to 2.5xlO 17 cm" 3 at the later stages of arc development, when flashover occurs. Differences between the rotational and excitation temperatures showed that the arc was not in a state of thermal equilibrium.…”

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confidence: 96%

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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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Section: Arc Discharge Temperature and Electron Density Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spectroscopic investigation of arc over an ice surface /

Nekahi¹

2011

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“…If the leakage current continues to increase, an unstable white arc will form along the iced insulator. When the white arc reaches its critical length, flashover occurs along the whole insulator [14,15].…”

Section: Introductionmentioning

confidence: 99%

Voltage Distribution and Flashover Performance of 220 kV Composite Insulators under Different Icing Conditions

Xie

Jiang

et al. 2018

Energies

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Abstract:Composite insulators are widely used in modern power systems to provide electrical insulation and mechanical support for transmission lines and substations. However, the insulation strength will decrease greatly under the combined conditions of ice-covering and contamination, and icing flashovers may take place under these serious conditions. In this paper, AC flashover tests of different artificially ice-covered 220 kV composite insulators were carried out in a multi-function artificial climate chamber under energized ice accumulation conditions. The test results indicate that, with the increasing of ice thickness, the flashover voltages decrease and tend to saturation. The icing flashover voltages can be increased by adding booster sheds, but excessive booster sheds can lead to lower flashover voltages under heavy icing conditions. The voltage distributions of the iced insulators were measured using experimental methods. The results show that, the air gaps withstand most of the applied voltage. The zinc oxide (ZnO) resistors that are contained in the insulators can influence the voltage distributions of the iced insulators, but have little affect on the icing flashover voltages. The work done in this paper can provide reference for the design and type selection of outdoor composite insulators in cold climate regions.

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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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Study of the Development of Positive Streamers Along an Ice Surface

Cited by 26 publications

References 24 publications

Spectroscopic investigation of arc over an ice surface /

Spectroscopic investigation of arc over an ice surface /

Voltage Distribution and Flashover Performance of 220 kV Composite Insulators under Different Icing Conditions

Atmospheric icing status and type of southwest China networks

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