Method for detecting bubble effect in oil paper insulation based on initial temperature envelope

A technology of oil-paper insulation and initial temperature, applied in the field of electrical equipment insulation, can solve the problems of increasing the risk of air bubbles and reducing the electrical strength of the transformer insulation system, and achieves the effects of fast calculation speed, rapid calculation and simple calculation process.

Pending Publication Date: 2022-06-21
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This somewhat increases the risk of bubble formation and reduces the electrical strength of the transformer insulation system

Method used

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  • Method for detecting bubble effect in oil paper insulation based on initial temperature envelope
  • Method for detecting bubble effect in oil paper insulation based on initial temperature envelope
  • Method for detecting bubble effect in oil paper insulation based on initial temperature envelope

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Effect test

Embodiment 1

[0065] The purpose of the present invention is to provide a method for detecting bubble effect in oil-paper insulation based on the initial temperature envelope, based on the dynamic model of bubble evolution, taking into account the effects of gas solubility in oil, water migration law and free water on the envelope. It can be widely used in oil-paper insulation systems with the same dynamic description. The calculated envelope can cover the onset temperature of the bubble effect obtained under different test conditions, and can adapt to water in the oil, gas saturation, and free cellulose on the surface of the oil. Extreme conditions such as water are of great significance to the study of the temperature limit of the transformer, which provides an important method basis for reducing the risk of bubble formation during the operation of the transformer.

[0066] like figure 1 As shown, the invention provides a method for detecting the bubble effect in the oil-paper insulation ...

Embodiment 2

[0113] Different from Embodiment 1, Process A and Process C and Process D are included.

[0114] Process C, based on the law of water migration, connect the water content in the cellulose material with the water vapor pressure, and calculate the water content in the cellulose material after migration;

[0115] Process D, consider the effect of free water on the surface of cellulose, and calculate the evaporation of free water.

[0116] Moisture content Z of paperboard at time t in step 8 described in Example 1 0 for Z water (t), which is calculated as:

[0117] Z water (t)=Z 0 -Z(t) (17)

[0118] Z(t)=(P vap (t) / 133·e -21.92+6850 / T(t) ) 0.75 (18)

[0119] At time t, the actual moisture content Z(t) of the board after migration cannot exceed the initial moisture content Z of the board 0 , the actual moisture content of the cardboard after migration is:

[0120] Z(t)=min(Z(t), Z 0 ) (19)

[0121] In the step 8, the amount of water vapor in the bubble at time t is n...

Embodiment 3

[0151] like figure 2 As shown in the figure, the graph is a graph of the Henry constant of different gases in mineral oil measured by W.J.McNutt and W.A.Fessler through experiments, which is generally recognized in the profession. The amount of water vapour species n after dissolution can be calculated from this graph vap and the quantity n of gaseous substances other than water vapour gas .

[0152] like image 3 As shown, for oil-immersed transformers, the cellulosic materials in it are: a "thick structure" for support, a "thin hot structure" wrapped around the windings, and a "thin cold structure" at normal oil temperature . When the local oil temperature rises, moisture is transferred from the "thin thermal structure" cellulose insulation to the "thick structure" monolithic insulation. As the overall temperature in the transformer increases, the surface moisture of the insulating material will begin to migrate into the oil. During the temperature rise, the migration...

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Abstract

The invention discloses a method for detecting a bubble effect in oil paper insulation based on initial temperature envelope. The method comprises the following steps: establishing a kinetic model formed by bubbles; on the basis of the Henry's law, the solubility of water vapor and gas except the water vapor in the oil at different temperatures and different pressures is calculated; on the basis of a water migration rule, the water content in the cellulose material is associated with the water vapor pressure, and the water content in the migrated cellulose material is calculated; the influence of free water on the cellulose surface is considered, and the evaporation capacity of free water is calculated; selecting upper and lower boundaries of the envelope; the method is based on a kinetic model formed by bubbles, influences of gas solubility in oil, a moisture migration rule, free water and the like on the envelope are considered, the envelope obtained through calculation can cover the bubble effect initial temperature obtained under different test conditions, the bubble generation risk in the transformer operation process is reduced, and the reliability of the transformer is improved. The method can be widely applied to an oil paper insulation system with the same dynamic description.

Description

technical field [0001] The invention relates to a method for detecting bubble effect in oil-paper insulation, in particular to a method for detecting bubble effect in oil-paper insulation based on an initial temperature envelope, and belongs to the technical field of electrical equipment insulation. Background technique [0002] Transformers are the core equipment of various power plants and substations. At the same time, the transformer is also the main equipment where accidents and faults occur frequently. Accidents caused by insulation failures account for more than 85% of all transformer accidents. Therefore, the insulation state and protection of the transformer are directly related to the safety and durability of the entire power grid. Existing transformer insulation systems generally consist of insulating oil and insulating materials such as cellulose paper or cardboard. Among them, cellulose insulation has a porous structure, which is easy to absorb water, resulti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/12G01N7/00G01K13/00
CPCG01R31/1281G01N7/00G01K13/00
Inventor 赵涛杨超杰刘云鹏
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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