scholarly journals Discharge Behavior and Morphological Characteristics of Suspended Water-Drop on Shed Edge during Rain Flashover of Polluted Large-Diameter Post Insulator

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1652
Author(s):  
Yifan Liao ◽  
Qiao Wang ◽  
Lin Yang ◽  
Zhiqiang Kuang ◽  
Yanpeng Hao ◽  
...  
Keyword(s):  
Electric Field ◽  
High Voltage ◽  
Large Diameter ◽  
Great Influence ◽  
Morphological Characteristics ◽  
Water Droplets ◽  
Power Stations ◽  
Water Drops ◽  
Post Insulator ◽  
Ultra High Voltage

Rain is one of the dominant meteorological factors threatening the outdoor insulation performance of ultra-high voltage (UHV) power stations. Discharge occurring on the polluted surface of post insulators in rain has always been a major concern of power stations. Previous studies have shown that suspended water droplets on the shed edge play an important role in the rain flashover process. In this work, artificial contamination rain flashover tests were carried out in a laboratory on a UHV DC (Ultra-High Voltage Direct Current) large-diameter composite post insulator, which had a rod diameter of 625 mm and alternating sheds (105 mm and 75 mm for larger and smaller shed overhang, respectively). The discharge mechanism was analyzed base on the observation of discharge phenomenon of suspended water-drops on the shed edge. Moreover, simulation models by COMSOL Multiphysics were established to investigate the electric field around sheds and suspended water-drops, as well as the shape change of water droplets on the insulation surface, especially at the edge of the shed. Results show that the shape parameters of water-droplets changed continuously under the combined action of gravity, surface tension, and capillary tension. Suspended water-droplets on the shed edge showed a great influence on the electric field distribution, and the resulting discharge lead to the bridging between sheds. This work paves a new way to revealing the contamination rain flashover mechanism on post insulators and provides critical knowledge for power stations on preventing flashover accidents.

Study on Discharge of Separated Water Droplets in DC Field

2011 ◽  
Vol 130-134 ◽  
pp. 3276-3279
Author(s):  
Zong Xi Zhang ◽  
Shan Feng Yin
Keyword(s):  
Electric Field ◽  
Hydrophobic Surface ◽  
Electrical Equipment ◽  
Water Droplets ◽  
Surface Flashover ◽  
Voltage Drops ◽  
Flashover Voltage ◽  
Dc Electric Field ◽  
Water Drops ◽  
And Migration

With the accelerating construction of strong smart grid, and the grid voltage level rising, performance requirements for the electrical insulation of electrical equipment also continue to increase. In terms of the advantages of RTV on antifouling, RTV-based paints coated insulator coating capacity of its flash tolerance can significantly increase, mainly due to RTV coating hydrophobic hydrophobicity and migration. But when the hydrophobic surface is in the fully wet, many small drops of water in the surface will be gathered into big drops of water, and these large droplets will distort the surface electric field of the medium. So the flashover voltage of the hydrophobic surface’s separated water droplets under DC electric field are analyzed comparatively in this paper, while some influencing factors such as different medias and volume of water drops, are introduced in specific experiments, and their effects on the flashover voltage are analyzed; under DC electric field experiment on the surface of hydrophobic and hydrophilic surface flashover voltage drops separation characteristics were studied.

scholarly journals Study of the Behavior of Water Droplets Under the Influence of a Uniform Electric Field on Conventional Polyethylene and on Crosslinked Polyethylene (XLPE) with MgO Nanoparticles Samples

2017 ◽  
Vol 7 (1) ◽  
pp. 1323-1328 ◽  
Author(s):  
C. Charalambous ◽  
M. Danikas ◽  
Y. Yin ◽  
N. Vordos ◽  
J. W. Nolan ◽  
...  
Keyword(s):  
Electric Field ◽  
Uniform Electric Field ◽  
Water Droplets ◽  
Nano Structure ◽  
Insulating Materials ◽  
Mgo Nanoparticles ◽  
Underground Cables ◽  
Flashover Voltage ◽  
Surface Damages ◽  
Water Drops

It is well known that polyethylene (PE) and cross-linked polyethylene (XLPE) are suitable insulating materials for underground cables. Samples of PE and of XLPE with MgO nanoparticles were investigated regarding their flashover behaviour with a uniform electric field and water droplets of various conductivities. In the present paper, the effect of the mounting arrangement of the water drops on the value of the flashover voltage and the effect of the volume of dripping water on the flashover voltage were also studied. Surface damages were analyzed using Scanning Electron Microscopy (SEM) studies and the study of the nano-structure of the samples was studied using the SAXS system.

scholarly journals Non-Uniform Distribution of Contamination on Composite Insulators in HVDC Transmission Lines

2018 ◽  
Vol 8 (10) ◽  
pp. 1962 ◽  
Author(s):  
Zhijin Zhang ◽  
Xinhan Qiao ◽  
Shenghuan Yang ◽  
Xingliang Jiang
Keyword(s):  
Electric Field ◽  
High Voltage ◽  
Transmission Lines ◽  
Fossil Fuels ◽  
Great Influence ◽  
Windward Side ◽  
Bottom Surface ◽  
Leeward Side ◽  
Uniformity Coefficient ◽  
Electric Field Force

In recent years, the air particulate pollutants formed by the combustion of fossil fuels and the emission of industrial waste gases have constantly been produced, and the polluted particles deposit also seriously affects social production and people’s lives. For instance, pollution-induced flashover is seriously threatening the safe operation of the power system, while insulator pollution non-uniformity has great influence on the flashover voltage of insulators. Therefore, in this paper both field contamination experiments of HVDC (High Voltage Direct Current) transmission lines and wind tunnel contamination simulation tests were conducted, and pollution non-uniformity coefficient KT/B, KW/L and KH/M were proposed and obtained. The results showed that the degree of contamination on top surface and leeward side is heavier than that on bottom surface and windward side. Thus, in the DC energized condition, contamination along the string is also non-uniform, and serious pollution occurs mainly in the high voltage terminal. In order to explain the uneven distribution phenomenon along the string, the coupling-physics model of composite insulator string was established and using the finite element method, the electric field around the insulator was simulated. Furthermore, basing on the field charging theory, the value of electric field force on particles around the insulator surface was calculated and the mechanism of non-uniformity along the insulator sting was then explained. The results are very important for guiding insulation design and field anti-pollution works.

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