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Method for evaluating aging degree of main insulation of transformer

A technology of aging degree and main insulation, applied in instruments, measuring electrical variables, testing dielectric strength, etc., can solve problems such as difficulty in insulating cardboard, aging diagnosis and limitations of unused large power transformers

Active Publication Date: 2012-12-12
云南电力试验研究院(集团)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For the evaluation of insulation aging status, it has been confirmed that insulation aging has a strong correlation with frequency-domain dielectric spectrum, but it is still limited to laboratory research and has not been used for aging diagnosis of large power transformers, and oil-paper insulation The frequency domain spectrum of the paper board is easily affected by moisture, temperature and other factors, especially how to distinguish the influence of moisture and aging on the dielectric properties of oil-paper insulation, and the effective evaluation of the moisture content and aging state of insulating paperboard has always been a difficulty in research at home and abroad.

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  • Method for evaluating aging degree of main insulation of transformer
  • Method for evaluating aging degree of main insulation of transformer
  • Method for evaluating aging degree of main insulation of transformer

Examples

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Embodiment 1

[0051] In order to effectively distinguish the influence of moisture and aging on the frequency-domain dielectric spectrum of insulating paperboard, and to accurately evaluate its insulation state, it is necessary to carry out a large number of experiments in the laboratory, extract characteristic parameters, and establish experience in evaluating the moisture content and aging degree of insulating paperboard formula.

[0052] The laboratory measured the frequency-domain dielectric spectrum of oil-impregnated insulating paperboard at 30°C, and established an empirical formula to characterize the insulating state of the paperboard. The insulating oil is 25# naphthenic transformer oil produced in Karamay, Xinjiang, and the insulating cardboard is 1mm thick Weidmann cardboard. The dielectric response analyzer developed by OMICRON is selected to measure the frequency domain dielectric spectrum. The peak value of the measured voltage is 100V, and the measured frequency range is 10 ...

Embodiment 2

[0067] The main insulation of a 500kV three-phase split single-phase autotransformer phase A is oil-impregnated cardboard. The insulating oil is 25# naphthenic transformer oil, the insulating cardboard is Weidmann cardboard, and the type of insulating material is the same as that in Example 1. Therefore, when evaluating the main insulation state of the transformer, the empirical formula established in Example 1 for evaluating the moisture content and aging degree of the insulating cardboard can be used to evaluate the insulation state. During the field test, since the arrester connected to the high voltage winding of the transformer is grounded and cannot be disconnected, the field can only measure the frequency domain dielectric spectrum and evaluate the insulation state of the main insulation between the medium and low voltage windings.

[0068] Step 1) On-site measurement of the frequency domain spectrum of the complex capacitance of the main insulation between the medium a...

Embodiment 3

[0097] Such as Figure 4 , is the dielectric loss factor frequency domain spectrum of new insulating paperboard with a certain moisture content measured in the laboratory. The cardboard is a Weidmann cardboard with a thickness of 1mm, the measurement voltage is 100V (peak value), and the measurement temperature is 30°C. 10 -1 Hz, 10 0 Hz, 10 1 The dielectric loss factor at Hz is substituted into the empirical formula in Table 1, and the moisture content of the cardboard is obtained respectively: 0.71%, 0.70%, and 0.66%, and the insulating cardboard is in a dry state. The actual moisture content of the cardboard measured by DL32Karl Fisher moisture meter is 0.68%, and the measured value is close to the evaluation result, which shows the validity of the method. Pick 10 -3 Hz, 10 -2 The dielectric loss factor at Hz is substituted into the fitting formula shown in Table 2, and the degree of polymerization of the cardboard is obtained as 978. The paperboard is a new insulati...

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Abstract

The invention discloses a method for evaluating the aging degree of main insulation of a transformer. The method comprises the following steps of: firstly measuring a complex capacitance frequency domain spectrum C*(ohm) and an oil conductivity sigma of the main insulation of the transformer on the scene, collecting structure parameters of the main insulation of the transformer and transmitting the structure parameters to a data processing device; subsequently calculating the complex capacitance frequency domain spectrum so as to obtain a medium loss factor frequency domain spectrum of a main insulation paper board of the transformer; and finally evaluating the state of the main insulation of the transformer by adopting frequency domain-based dielectric characteristic parameters. The method considers the influence of multiple factors such as measuring temperature, a main insulation structure, and oil conductivity, and has wide applicability to an oil-immersed transformer; the defects in a traditional chemical and electric method are compensated; the moisture content of the main insulation of the transformer can be diagnosed, and meanwhile the aging state of the insulation can be evaluated; and moreover the method can be used for on-site diagnosis directly, and has the advantages of lossless, convenience, transplantation and the like.

Description

technical field [0001] The invention relates to the field of electrical equipment insulation aging and life prediction, in particular to an evaluation method for the oil-paper insulation aging state of an oil-immersed power transformer. Background technique [0002] The power transformer is the core of energy conversion in the process of power transmission and distribution, and is one of the most important equipment in the safe operation of the power grid. The transformer oil-paper insulation system is gradually degraded by the combination of temperature, moisture, oxygen and other factors during long-term operation, resulting in a decline in its electrical and mechanical properties, thus endangering the safe operation of the transformer and the entire power grid. At present, many large-scale transformers in my country have been operating for more than 20 years, reaching the end of the design service life. How to accurately assess the aging condition of transformer insulati...

Claims

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Application Information

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IPC IPC(8): G01R31/12G01R27/26
Inventor 文华赵现平杨丽君马志钦廖瑞金王耀龙齐超亮贡春艳郝建
Owner 云南电力试验研究院(集团)有限公司
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