Variable-voltage dielectric response test method for evaluating moisture state of oil paper insulation
A technology of oil-paper insulation and dielectric response, applied in the direction of testing dielectric strength, etc., can solve the problems of difficult acquisition of structural parameters, limited evaluation, and evaluation of structural impact.
Pending Publication Date: 2022-04-29
CHONGQING UNIV
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Problems solved by technology
[0011] The traditional FDS test method needs to spend a lot of time to establish an offline database of insulating cardboard samples with different moisture contents, and the structure of the oil-paper insulation equipment is complex. Although the X-Y model is considered to be able to link the actual insulation structure FDS with the insulating cardboard sample FDS in the offline database, but On the one hand, the validity of the model conversion lacks systematic verification, which may have a great impact on the evaluation structure. On the other hand, the structural parameters X and Y are usually difficult to obtain. These factors greatly limit the evaluation of the moisture content of oil-paper insulation with different structures by this method.
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[0052] The application will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, but not to limit the protection scope of the present application.
[0053] The present invention is mainly based on the non-linear characteristics of oil-paper insulation with different structures under low-frequency excitation after being damp. Voltage and the maximum excitation voltage differ by 20 times) nonlinear coefficient, and fitting to obtain the functional relationship between moisture content and nonlinear coefficient at different temperatures; then apply low-frequency sinusoidal excitation voltage of different amplitudes to the oil-paper composite insulation to be tested, and collect the response The current signal is used to obtain the nonlinear coefficient of the transformer to be tested, which is substituted into the functional relationship between t...
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The invention discloses a variable-voltage dielectric response test method for evaluating the moisture state of oil paper insulation. A nonlinear coefficient under low-frequency sine excitation is used as a characteristic parameter for reflecting the moisture state. The method comprises the following steps: under laboratory conditions, measuring nonlinear coefficients of oil paper insulation samples with different moisture contents at different temperatures during low-frequency excitation (suggested to be less than 1Hz), and fitting to obtain a function relationship between the moisture contents and the nonlinear coefficients at different temperatures; applying low-frequency excitation voltage signals with different amplitudes to the to-be-tested oil-paper composite insulation, acquiring response current signals to obtain a nonlinear coefficient of the to-be-tested transformer, substituting the nonlinear coefficient into a function relation between the moisture content and the nonlinear coefficient at the test temperature corresponding to the excitation frequency, and quantitatively evaluating the moisture degree of the oil-paper composite insulation; therefore, the purpose of effectively evaluating the oil-paper composite insulation damp state under the condition of unknown structural parameters is achieved.
Description
technical field [0001] The invention relates to the field of moisture evaluation of oil-paper insulation, in particular to a variable voltage dielectric response test method for evaluating the moisture state of oil-paper insulation. Background technique [0002] Moisture of oil-paper insulation is an important factor affecting the reliability of oil-immersed electrical equipment. It is a major demand in the power industry to obtain the moisture content of oil-paper insulation inside the equipment through non-destructive testing methods without hood sampling. Dielectric response test is a non-destructive test method that is widely used at present. The obtained frequency domain dielectric spectrum (FDS) has the advantage that the test is less disturbed by noise, and is often used to evaluate the moisture content of oil-paper insulation. [0003] In this method, the FDS curves of oil-impregnated paperboards with different moisture contents are measured in the laboratory and for...
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Login to View More IPC IPC(8): G01R31/12
CPCG01R31/12
Inventor杨丽君李威夏源成立赵学童郝建廖瑞金袁媛
OwnerCHONGQING UNIV