Direct-current bushing voltage-sharing device based on low-conductivity temperature coefficient epoxy composite material

Abstract

The invention relates to a direct-current bushing voltage-sharing device based on a low-conductivity temperature coefficient epoxy composite material. A current-carrying conductor is arranged in the center of a bushing, an outer conductor is coaxially arranged outside the current-carrying conductor, a thermal insulation air gap is arranged between the current-carrying conductor and the outer conductor, and an epoxy capacitor core is wrapped outside the outer conductor. A voltage-sharing aluminum foil is arranged in the epoxy capacitor core, the bushing capacitor core is located in the bushing, and SF6 insulating gas is filled between the bushing capacitor core and the bushing. A metal flange is installed at the lower end of the bushing and outside the sleeve capacitor core, and the lower end of the bushing capacitor core is immersed in transformer oil. After the epoxy resin in the high-voltage direct-current bushing is replaced with the epoxy resin composite material with the low conductivity temperature coefficient, the internal electric field of the capacitor core is remarkably homogenized, the maximum radial and axial electric field intensity is effectively reduced, and the electric field distortion is weakened.

Description

technical field [0001] The invention belongs to the technical field of high-voltage DC bushings, in particular to a DC bushing voltage equalizing device based on epoxy composite materials with low conductivity temperature coefficient. Background technique [0002] HVDC bushing is the key equipment of the converter station, its safe and reliable operation is directly related to the stability of the DC transmission system. However, in the actual operation process, the bushing capacitor core is subjected to the combined effect of electrothermal coupling, which becomes the main reason for its failure. [0003] The DC bushing usually adopts the design method of the AC bushing, that is, the design method of equal capacitance and equal steps. This method can make the axial and radial field strength inside the capacitor core evenly distributed. However, under rated working conditions, the Joule heat and dielectric loss of the current-carrying conductor form a temperature gradient i...

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Problems solved by technology

In this case, using a capacitor core made of pure epoxy resin will cause the electric field to increase in the radial direction, and its maximum radial field strength is as high as 9.3kV / mm, which is 8kV / mm higher than the design field strength, which can easily cause discharge.

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