Frequency-domain dielectric theory-based evaluation method for evaluating insulation aging state of oiled paper of transformer

Abstract

The invention discloses a frequency-domain dielectric theory-based evaluation method for evaluating the insulation aging state of the oiled paper of a transformer. According to the method, the transformer is cooled and short-circuited. Then the changing curve of the real part and the imaginary part of a complex dielectric constant along with the frequency is obtained via the domain spectrometry means based on the frequency-domain dielectric theory. After that, a polarized dual-relaxation model is adopted and the damage conditions of two principal polarization modes, namely the interfacial polarization and the ionic polarization, to an oiled paper insulating system can be respectively represented through the front and back portions of the model. Finally, characteristic parameters obtained through calculation are compared with the standard values of the characteristic parameters. Through the above five steps of the method, the state of the oiled paper insulating system of the transformer can be effectively diagnosed, so that the invention provides an advanced, lossless and non-destructive detection method. The method can be used for evaluating and diagnosing the insulating state of the oiled paper insulating system of an oil-immersed transformer that is put to use for a long time. Therefore, the safety operation of the power grid is ensured.

Description

technical field [0001] The invention belongs to the field of insulation state diagnosis and life evaluation of transformer oil-paper insulation, and relates to a characteristic parameter evaluation method of oil-paper insulation aging state based on dielectric theory in frequency domain in dielectric response theory. Background technique [0002] Oil-paper composite insulation system is often used in power equipment, such as transformers, cables, etc. As an important part of the power grid, the transformer’s normal operation ensures the reliability of the power grid. The insulation system of the oil-immersed transformer is mainly composed of internal insulation and external insulation. The internal insulation is an important part of the entire insulation. If the state of the internal insulation can be detected , it can directly determine whether the transformer can operate normally, which becomes the premise and basis for the condition maintenance of oil-paper insulated powe...

AI Technical Summary

Problems solved by technology

However, due to the influence of factors such as energy shortage, load increase, and maintenance cost reduction in recent years, the original preventive test has gradually transformed into a condition-based maintenance system due to long maintenance cycles, lack of authenticity, and insufficient or excessive maintenance. In actual implementation, there are still many problems in how to make a good evaluation of the insulation condition and remaining life of the equipment

[0004] The methods that have been used to judge the oil-paper insulation system mainly include: furfural analysis, tension measurement, polymerization degree measurement, etc., but because the method itself and the operation are prone to large errors, the accuracy of the results is relatively low

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