Oilpaper insulation system relative dielectric constant test method under low-frequency sine excitation

Abstract

The invention discloses an oilpaper insulation system relative dielectric constant test method under low-frequency sine excitation. An actually measured parameter temperature is obtained through a test, a ratio of the total thickness of a paper cylinder to a main insulation thickness between high and low-voltage windings and a ratio of the total width of a stay to main insulation average perimeter between the high and low-voltage winding are obtained through testing, then the tested data is substituted into a relative dielectric constant expression of an oilpaper insulation system under the low-frequency sine excitation, and finally, a relative dielectric constant of a transformer oil gap under the low-frequency sine excitation is obtained. According to the method, on the basis that the relative dielectric constant of the oilpaper insulation system under the low-frequency sine excitation is effectively calculated, the problem of long time consumed for measuring dielectric parameters of the oilpaper insulation system under the low-frequency sine excitation by use of an instrument can also be solved through a valve calculation method, and the application efficiency of a frequency domain dielectric response method in actual engineering is improved.

Description

technical field [0001] The invention belongs to the field of transformer insulation state detection, and in particular relates to a method for testing the relative dielectric constant of an oil-paper insulation system under low-frequency sinusoidal excitation. Background technique [0002] The oil-immersed transformer is the core equipment of the power system. The performance of the internal oil-paper insulation system is an important factor affecting the life of the transformer. Frequency Domain Dielectric Spectrum (FDS) can effectively diagnose the moisture content of the oil-paper insulation system. One of the recognized methods for content and its aging state. The oil-paper insulation system is a composite dielectric. The oil-paper insulation system of an oil-immersed transformer is mainly composed of an oil gap, a paper tube pressure plate and a stay. In related studies, the XY model is often used as its geometric equivalent model. The dielectric of the oil-paper insula...

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Problems solved by technology

[0003] When the oil-paper insulation system is used for the frequency-domain dielectric response test, the external sinusoidal excitation voltage is scanned from high frequency to low frequency. Generally, it takes 40 minutes to scan from 1KHz to 1mHz, and it takes 15 minutes to test only 1mHz frequency. For special working conditions, if the traction transformer maintenance time (opening the skylight) is only about 2 hours, the transformer maintenance time at this time is not enough to complete the two links of transformer offline cooling and frequency domain dielectric response test, which seriously affects the frequency domain dielectric Therefore, there is an urgent need for a method that can improve the application efficiency of the frequency domain dielectric response method in actual engineering on the basis of accurately obtaining the frequency domain spectrum of the relative permittivity of the transformer oil-paper insulation system.

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