Flashover characteristics of artificial polluted UHV AC bushing insulators

Abstract

Ultra High Voltage (UHV) transmission system will be the key power network of Chinese power grid in the future. The appropriate external insulation design of insulators for different contamination area is one of the most important guarantees for security and stability. In order to give some technical references for insulation design of UHV bushing insulator, artificial pollution tests have been carried out for UHV bushing insulator in the laboratory of State Grid and some flashover characteristics have been obtained in the paper. The experimental results shown that the maximum pollution withstand voltage U max are affected by equivalent salt deposit density ρ ESDD , and the correction formulas of the maximum pollution withstand voltage are pointed out. In addition, the relationship between the 50% pollution flashover voltage U 50 and the diameter of bushing insulators have been analyzed, the results shown that the 50% pollution flashover voltage is also affected by the diameter of bushing insulator, at the same pollution level, the flashover voltage of small diameter insulator is higher than large diameter insulator. The diameter correction factor K D of large diameter bushing insulator was given based on test results. Finally, according to test conclusion and design experience about external insulation of bushing insulators, the paper give some dimension parameters of UHV AC bushing insulators for contamination insulation design.

Effect of vertical electric field components on the local arc development along contaminated surfaces

“…The parameters characterizing the dry zone satisfy equation (10), prompting the arc's transformation into a sliding discharge. Subsequently, the flashover voltage and creepage distance align with the Toepler equation, equation (11), wherein increasing the creepage distance does not appreciably enhance the flashover voltage. This observation mirrors the bushing accidents highlighted in a substation in Indonesia in the introduction section.…”

“…( ) = Equation (11) stipulates that the length of the arc is directly proportional to the fourth power of the voltage. While the coefficient k 2 in the electrode structure may vary between the flange case and the arc root case, it does not impede our examination of the arc development mechanism.…”

“…Kumar et al [9] extended this studies by testing the flashover voltage and discharge current of bushings under non-uniform pollution. Ozaki et al [10] and Xu et al [11] found that the pollution flashover voltage is influenced by the diameter of the bushings and the relationship between average diameter and withstand voltage could be described by a quadratic curve.…”

Research on the dynamic characteristics of electric field distribution of the ± 1100 kV Ultra high voltage converter transformer valve‐side bushing using weakly ionised gas conductance model

“…Converter transformer valve‐side bushings are located at the connection position of converter stations and alternating current (AC) line side systems, and are subjected to high voltage, large current and strong mechanical load simultaneously [1]. As the power grid voltage level increasing in China [2], in recent years, China's Yibin, Jinan, and Tianshan converter stations have occurred many explosion failures due to the breakdown of valve‐side bushings caused by the distortion of local electric field posing a serious threat to the safety operation of power grid.…”