Abstract
The corona onset characteristic of bundle conductors is an important limiting factor for the design of UHV AC power lines in high-altitude areas. An experimental study on the corona characteristics of 8 × LGJ630, 6 × LGJ720, 8 × LGJ720 and 10 × LGJ720 bundle conductors commonly used in UHV power lines under dry and wet conductor conditions, as well as artificial moderate and heavy rain conditions, was conducted in Ping’an County, Xining City (elevation 2200 m). By using the tangent line method, the corona onset voltages and onset electric field of four types of conductors at high altitudes are obtained for the first time. In addition, the calculation model of corona onset voltage considering the outer strands’ effect on the electric field and the geometric factor in the corona cage in high altitude areas is established. The comparison of the calculation results and experimental results under dry conditions verifies the model’s correctness. Based on the results, an optimal selection scheme for high altitudes is proposed. The roughness coefficient was also calculated and analysed: the roughness coefficient of bundled conductors was between 0.59 and 0.77, and the roughness coefficient of the wet conductor was between the dry and rainy conditions. Both the experimental data and the calculation model can provide a reference for conductor selection for UHV AC power lines for use in high-altitude areas.
Highlights
When the field strength around the conductor exceeds that of the air, the air near the conductor is ionised, generating corona discharge
When the voltage is smaller than U0 in the section ‘a’, the resistive current is very small, and the resistive current is produce by random and discrete corona discharge current is very small, and the resistive current is produce by random and discrete corona discharge points, including burrs and scratch on the conductor’s surface, joints between conductor and fittings, points, including burrs and scratch on the conductor’s surface, joints between conductor and fittings, etc., according to Peek’s law, the phenomenon occurring in section ‘a’ is called ‘disruptive voltage’
When the voltage is higher than U0, the corona discharge occurs on the whole surface of the
Summary
When the field strength around the conductor exceeds that of the air, the air near the conductor is ionised, generating corona discharge. The corona discharge may produce corona effects, such as: corona loss, audible noise, radio interference, etc. Which influence the environment and line operation [1,2,3,4,5,6]. The corona effect becomes more serious, especially in UHV lines. China has complex terrain and non-uniformly distributed energy resources and productivity, where 75% of the land sits above an elevation of 1000 m. UHV AC lines currently under construction and in planning will inevitably cross such high-altitude areas [7,8].
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