DC flashover performance and effect of sheds configuration on polluted and ice–covered composite insulators at low atmospheric pressure

Jiang, Xingliang; Chao, Yafeng; Zhang, Zhijin; Hu, Jianlin; Shu, Lichun

doi:10.1109/tdei.2011.5704498

Cited by 40 publications

(30 citation statements)

References 11 publications

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“…In contrast, the evolution of DC arcs to flashover on the distance scale greater than 1 m has not had similar experimental support until recently [58,[60][61][62]. In some ways, dc arc evolution to flashover is simpler than ac, because reignition does not occur, but the interaction of dc arc current with ice layer temperature, chemistry and resulting surface layer conductivity involve several branches of physics.…”

Section: Arc Evolution To Flashovermentioning

confidence: 99%

Insulator flashover under icing conditions

Farzaneh

2014

IEEE Trans. Dielect. Electr. Insul.

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Atmospheric ice accretion, combined with pollution, has been recognized as a significant risk factor in the reliability of line and station insulators in cold climate regions. Flashovers occurring on ice-and snow-covered insulators result from combinations of a number of factors and parameters. Electric fields modify the structure of ice, the shape and direction of icicle elongation, the distribution of liquid water and the geometry of air gaps that break up the continuous ice surface. Electric field strength and voltage polarity as well as corona space charge and ionic wind have demonstrable influences on the flashover process. Insulator icing flashover is also affected by changes in air temperature and several other environmental and meteorological conditions including ice type and structure. The presence of surface pollution and the rejection of ions from solid to liquid layers during the freezing and melting process also play a central role in the icing flashover of insulators, which can occur at normal operating voltage under the most adverse conditions. This paper presents an overview of these phenomena and describes the interactions that lead to the initiation and development of discharges on the ice surfaces covering the insulators, as well as their evolution to flashover. The lecture also includes the modeling of these phenomena, leading to successful prediction of the critical flashover voltage as well as to insight into the most practical solutions for improved insulator design and mitigating icing flashovers.

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Section: Arc Evolution To Flashovermentioning

confidence: 99%

Insulator flashover under icing conditions

Farzaneh

2014

IEEE Trans. Dielect. Electr. Insul.

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“…Jiang et al [81], [82], Su et al [83] and Liu et al [84] confirmed the influence of pollution on ice-covered insulator flashover.…”

Section: Effect Of Applied Water Conductivitymentioning

confidence: 88%

“…Jiang et al [82] The diameter of the insulator is a major factor influencing air gap formation and the electrical performance of insulators under icing conditions. Farzaneh et al [100] investigated the effect of the insulator diameter by controlling the width of the ice layer on insulator performance.…”

Section: Effect Of Insulator Type and Configurationmentioning

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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“…Additional refinements include the effect of multiple arc root voltage drops across air gaps [59], and the dynamic behavior of the arc itself. In contrast, the evolution of DC arcs to flashover on the distance scale greater than 1 m has not had similar experimental support until recently [58,[60][61][62]. In some ways, dc arc evolution to flashover is simpler than ac, because reignition does not occur, but the interaction of dc arc current with ice layer temperature, chemistry and resulting surface layer conductivity involve several branches of physics.…”

Section: Arc Evolution To Flashovermentioning

confidence: 99%

Insulator icing flashover

Farzaneh

2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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the insulator is a kind of important electric components, because it plays a role in electrical insulation and plays a supporting role in mechanical, power system and even the development of the whole society to a higher degree of dependence on the performance of insulators, the requirements are also rising. However, in recent years, China's domestic air pollution is serious, the weather conditions are complex, the icing flashover phenomenon has become a serious performance of insulator safety accidents. However, the proposed super hydrophobic materials in this paper, not only the anti icing flashover performance is better than the commonly used coating, and preparation process is sample, high performance, and low cost, which is expected to become a substitute for insulator coating now. the super hydrophobic coating is considered to be one of the important methods to solve the problem of flashover electrical equipment, so the study of high hydrophobicity flashover, super hydrophobic coating with high performance, simple process, low cost plays an important role in electrical equipment and power industry. In this paper, we will use a kind of method which is more powerful, graphene was prepared by electrochemical stripping and poly-two methyl siloxane in a certain proportion to prepare superhydrophobic surface. In this paper, the preparation of superhydrophobic surface, not only has excellent self-cleaning performance, but also has a very low corrosion current density. It is surprising that the superhydrophobic surface prepared by this method has good mechanical stability, and its surface can maintain the super hydrophobicity after the strong impact of the outside world. The method mentioned in this paper is not only capable of preparing a set of super hydrophobic surface self cleaning,mechanical stability is stable as a whole, it also provides a new idea for anti icing flashover of electrical equipment. 1. Introduction With the development of the electric power industry and the gradual improvement of the voltage level, the electrical equipment is playing a more and more important role in people's daily production and life. Of which the insulator is an important part of power system, however, the phenomenon of icing flashover has a great influence on the mechanical and electrical properties of insulators, which will threaten the stability and security of power system operation, resulting in huge economic losses. Take snow disaster in South China in 2008 as an example, the ice coating accidents spread to 13 provinces, State Grid economic losses in the accident up to 10 billion 450 million Yuan, and in daily life, line trip, outage accidents also occur caused by icing [1] , it causes a great impact on people's life. Therefore, it has become one of the most urgent problems to solve the problem of icing flashover. However, there are still a lot of defects in the deicing and anti icing methods currently used, and the efficiency is low and the energy consumption is large. Super hydrophobic coating is a kind of water ela...

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DC flashover performance and effect of sheds configuration on polluted and ice–covered composite insulators at low atmospheric pressure

Cited by 40 publications

References 11 publications

Insulator flashover under icing conditions

Insulator flashover under icing conditions

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

Insulator icing flashover

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