Study of the influence of altitude on the characteristics of the electrical arc on polluted ice surface =

Li, Yu-Ku

doi:10.1522/15248410

Cited by 8 publications

(9 citation statements)

References 41 publications

(86 reference statements)

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“…Over the past years, comprehensive investigations have been carried out at CIGELE to study the effect of applied water conductivity on the Vws of different types of ice-covered insulators under AC and DC voltages [18], [22], [29], [72], [85], [86], [87]. It is now an established fact that any increase in the freezing water conductivity lowers the flashover voltage.…”

Section: Effect Of Applied Water Conductivitymentioning

confidence: 99%

“…At high altitudes, the electric performance of insulators is enhanced by increasing air pressure [82], [103], [105], [106], [107]. Li et al [87] introduced a relationship between the critical flashover voltage V c at any pressure and that, at standard sea level V o is as follows:…”

Section: Effect Of Air Pressurementioning

confidence: 99%

“…The value of m depends on a number of elements such as insulator shape, pollution severity, and voltage type [87]. Several investigations showed the flashover voltage decreases up to 40%, when the air pressure drops from its sea level value of 101.3 kPa to 30 kPa…”

Section: Effect Of Air Pressurementioning

confidence: 99%

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Two-arc dynamic modeling of AC and DC flashovers of EHV post station insulators covered with ice based on laboratory experiments /

Ledari¹

2014

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Ice and snow accretion on insulators has been recognized as a significant risk factor in the reliability of overhead transmission lines and substations. Accumulated ice on insulators can initiate corona discharge along ice-free zones, often called air gaps. In the presence of a highly conductive water film on the surface of the ice, while applied voltage is sufficiently high, corona discharge activity may be initiated and developed into partial arcs. Under certain conditions, these partial arcs may result in complete flashover.The general objective of this research is to study the flashover phenomenon on icecovered extra-high-voltage (EHV) post insulators. Hence, a two-arc dynamic model based on the existing mathematical models was proposed to predict the parameters of AC and DC flashovers. The model considers the arc as time-dependent impedance constituted of a resistance in series with an inductance. The residual ice layer is defined in terms of an equivalent resistance, where the equivalent surface conductivity is calculated by taking into account the water film flowing along the ice surface. The present contribution proposes a novel approach to determine the equivalent surface conductivity, based on fluid mechanics and the Navier-Stokes equations, as well as on a series of experiments carried out to measure the water film flow rate and conductivity.Moreover, the mechanisms of discharge initiation and arc development on the surface of the ice accumulated on the insulators were studied. Special attention was paid to evaluate the effect of the volume conductivity of the ice surface on the arc propagation velocity for different freezing water conductivities, using high-speed video camera techniques.The proposed models were successfully validated in laboratory using station post insulators -typically used in Hydro-Quebec 735 kV substations -under AC and DC voltages. The maximum AC and DC withstand voltages were experimentally determined based on IEEE Std 1783. Furthermore, the influence of the number and position of air gaps on the flashover performance of ice-covered insulators was investigated experimentally. Experimental results revealed that the air gap configuration affects the maximum withstand voltage significantly. The main characteristics of flashover, including minimum flashover voltage and leakage current, derived from the proposed two-arc dynamic model, respond properly to the variation of major parameters, namely, insulator length and freezing water conductivity.Finally, in order to interpret the performance of insulators under different air gap positions, the voltage and electric field distributions along the ice-covered insulator were simulated numerically during the melting period, using the Finite Element Method (FEM). Simulations results confirm that increasing the number of air gaps improves the maximum withstand voltage and uniformity of voltage distribution of EHV post insulators. Based on the results, the use of booster sheds and grading rings to improve the insulating performance of...

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Section: Effect Of Applied Water Conductivitymentioning

confidence: 99%

Section: Effect Of Air Pressurementioning

confidence: 99%

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Two-arc dynamic modeling of AC and DC flashovers of EHV post station insulators covered with ice based on laboratory experiments /

Ledari¹

2014

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“…The change of constants of the partial arc and the arc floating phenomenon are the main reasons for the decrease of the pollution flashover voltage at low air pressure [19]. Consulted [20,21], the relationship between the pollution flashover voltages of insulators and the air pressure P can be expressed as:…”

Section: Relationship Between Pollution Flashover Voltages and Altitudesmentioning

confidence: 99%

Study on Pollution Flashover Performance of Short Samples of Composite Insulators Intended for /spl plusmn/800 kV UHV DC

Jiang

Yuan

Zhang

et al. 2007

IEEE Trans. Dielect. Electr. Insul.

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Based on the artificial pollution tests, the effects of pollution and high altitude on the flashover performance of short samples of five kinds of UHV/EHV dc composite long rod insulators are analyzed. The exponent characterizing the influence of salt deposit density on the flashover voltage is related with the profile and the material of the insulator shed. The values of the samples' exponents vary between 0.24 and 0.30, which are smaller than those of porcelain or glass cap-and-pin insulators, namely, the influence of the pollution on the composite long rod insulators is less, relatively. Thus, the composite insulators have certain advantages in severe pollution regions. The best ratio of the leakage distance to the arcing distance is about 3.35. The exponent characterizing the influence of air pressure on the flashover voltage is related with the profile and the material of the insulator shed and the pollution severity, the values of the samples' exponents vary between 0.6 and 0.8, which are larger than those of porcelain or glass cap-and-pin insulators. Therefore, the dc composite insulator used in high altitude regions should have enough arcing distance. Based on the test results, if insulator sample Type E is selected for the ±800 kV UHV dc transmission lines, the basic arcing distance should be no less than 8.16 m and the basic leakage distance no less than 30.2 m.

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“…The method of determining the conductivity refers to requirements of a common procedure in the laboratories of CIGELE of UQAC [61] and other institutes [52] [104] [108] are to measure the freezing water conductivity before forming ice and icicles. To obtain water with certain conductivity, NaCl is added to de-ionized water while its conductivity is…”

Section: Freezing Water Conductivitymentioning

confidence: 99%

Study of electric discharge and space charge formation phenomena in the air gaps of an ice-covered insulator using an icicle/ice-covered plate electrode system =

Yu¹

2007

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Study of the influence of altitude on the characteristics of the electrical arc on polluted ice surface =

Cited by 8 publications

References 41 publications

Two-arc dynamic modeling of AC and DC flashovers of EHV post station insulators covered with ice based on laboratory experiments /

Two-arc dynamic modeling of AC and DC flashovers of EHV post station insulators covered with ice based on laboratory experiments /

Study on Pollution Flashover Performance of Short Samples of Composite Insulators Intended for /spl plusmn/800 kV UHV DC

Study of electric discharge and space charge formation phenomena in the air gaps of an ice-covered insulator using an icicle/ice-covered plate electrode system =

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