Method for evaluating insulation state of capacitive oil-paper transformer bushing

Abstract

The method for evaluating the insulation state of a capacitive oil-paper transformer bushing according to the invention belongs to the technical field of electrical equipment insulation diagnosis, relates to the insulation diagnosis of a capacitive oil-paper bushing, and in particular relates to a method for evaluating the insulation state of a capacitive oil-paper bushing. This method combines mathematical modeling and simulation with laboratory tests to perform mathematical exponential function fitting on the frequency domain spectrum curve of the bushing capacitance, and uses the integral of the fitting function to calculate the variation of the frequency domain spectrum curve under different insulation states. It is described, so as to achieve accurate and non-destructive evaluation of the insulation state of the bushing by applying the frequency-domain dielectric spectroscopy method. The method can accurately evaluate the insulation state of the bushing without disassembling and testing the bushing, and the method is simple and easy. The insulation state of the capacitive oil-paper bushing can be accurately and effectively evaluated on site, and an accurate basis can be provided for the maintenance and replacement of the bushing.

Description

technical field [0001] The invention belongs to the technical field of electrical equipment insulation diagnosis, and relates to the insulation diagnosis of a capacitive oil-paper bushing, in particular to a method for evaluating the insulation state of a capacitive oil-paper bushing. technical background [0002] As the core of energy conversion in the process of power transmission and distribution, the power transformer is one of the most critical equipment for the safe and stable operation of the power grid. The bushing of a high voltage transformer is a key component of the transformer. During the operation of the bushing, it will be affected by the operating environment such as high-voltage electric field, magnetic field and temperature. The insulation will deteriorate, the insulation performance will drop, and even the insulation effect will be completely lost, resulting in the failure of the bushing and the power transformer. The capacitor core of the bushing is the ...

AI Technical Summary

Problems solved by technology

[0004] (1) The content of dissolved gas and furfural in the oil in the chemical method will change due to transformer oil change and maintenance, and cannot accurately characterize the insulation state of the casing oil-paper insulation structure

The degree of polymerization of insulating paper is widely considered to be the most basic characteristic quantity for evaluating the state of oil-paper insulation at home and abroad. However, to test the degree of polymerization of equipment, the bushing must be disassembled and sampled, which brings certain difficulties to the application of the degree of polymerization to evaluate the insulation state.

[0005] (2) The dielectric loss factor and capacitance evaluation methods evaluated by electrical methods, the sensitivity of the two to find the insulation fault of the bushing is reduced by the defect-to-insulation volume ratio of the bushing, and even the change and defect of the insulation state cannot be detected in time ;

[0006] (3) The method of three-phase bushing vector sum is greatly affected by signal acquisition and transformer operating environment, and has not been widely used in practical applications

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