Evaluation method and system for damp invasion point of oil paper insulation sleeve

Abstract

The invention discloses a method and a system for evaluating a damp invasion point of an oil-paper insulating sleeve. The method comprises the following steps: carrying out offline standing treatment on the oil-paper insulating sleeve at different damp invasion points, carrying out dielectric loss test on different types of sleeves in a frequency range of 1mHz to 1kHz, obtaining dielectric loss data at each frequency point, drawing a frequency-dielectric loss value curve, carrying out image feature analysis on the curve, and proposing a relaxation offset factor and a high-frequency notch factor. And according to the numerical value of the composite relaxation missing factor, judging the type of a damp invasion point of the oil-paper insulating sleeve. According to the method, the relaxation offset characteristic and the high-frequency gap characteristic of the frequency dielectric loss curve are comprehensively utilized, the composite relaxation missing factor is constructed, accurate identification of the type of the wetting invasion point of the oil paper insulating sleeve is realized, and an effective technical means is provided for fault diagnosis and state evaluation of power equipment.

Description

Technical Field

[0001] This invention belongs to the field of electrical equipment insulation condition diagnosis technology, specifically relating to a method and system for assessing moisture intrusion points in oil-paper insulating bushings. Background Technology

[0002] Oil-paper insulating bushings are crucial components of key equipment such as power transformers, and their insulation performance directly affects the safe and reliable operation of the equipment. During long-term operation, bushings may become damp due to factors such as seal failure and environmental humidity. The location of the moisture intrusion point will have different effects on the dielectric properties of the bushing. Traditional dielectric loss testing methods mainly focus on the change in dielectric loss value at a single frequency point or a narrow frequency band, making it difficult to effectively identify the specific location of the moisture intrusion point. While existing technologies include methods for assessing insulation status through broadband dielectric loss spectrum analysis, most studies only focus on the degree of moisture absorption, lacking effective means to distinguish different types of moisture intrusion points. This leads to inaccurate fault location and affects the targetedness and effectiveness of subsequent maintenance decisions. Therefore, there is an urgent need for a method that can accurately identify the type of moisture intrusion point in oil-paper insulating bushings. Summary of the Invention

[0003] In order to effectively locate the moisture intrusion point of oil-paper insulating bushing, the present invention provides an assessment method and system for the moisture intrusion point of oil-paper insulating bushing, which realizes the accurate identification of the type of moisture intrusion point of oil-paper insulating bushing, and provides an effective technical means for fault diagnosis and condition assessment of power equipment.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for assessing the moisture intrusion point of an oil-paper insulating sleeve, comprising the following steps:

[0005] Step 1: Prepare oil-paper insulating sleeves with different moisture intrusion points and place them in the same ambient temperature; the different moisture intrusion points are no moisture intrusion point, flange moisture intrusion point, upper ceramic moisture intrusion point, general cap moisture intrusion point, and global moisture intrusion point;

[0006] Step 2: Record the ambient temperature as T, in K. Perform dielectric loss tests on the oil-paper insulating sleeves at different moisture intrusion points within the range of 1 MHz to 1 kHz to obtain dielectric loss data.

[0007] Step 3: Connect the dielectric loss data obtained at different frequencies in sequence according to the frequency magnitude, and plot the dielectric loss curves at different moisture intrusion points;

[0008] Step 4: Determine the point of moisture intrusion.

[0009] In a preferred embodiment, the relaxation offset factor is calculated using formula (1) based on the dielectric loss curve. ;

[0010] (1)

[0011] In the formula, This represents the frequency corresponding to the lowest dielectric loss value at different intrusion points. This represents the frequency corresponding to the lowest dielectric loss value without moisture intrusion.

[0012] In a preferred embodiment, the high-frequency gap factor is calculated using formula (2).

[0013] (2)

[0014] In the formula, This represents the dielectric loss value at a frequency of 1kHz, representing the point of global moisture intrusion. This represents the dielectric loss value for frequencies ranging from 1 MHz to 1 kHz, excluding 1 kHz. The value represents the Heaviside step function, N represents the number of frequency points in the range of 1 mHz to 1 kHz, and j represents the j-th frequency point.

[0015] In a preferred embodiment, the composite relaxation missing factor is calculated using formula (3).

[0016] (3)

[0017] Through composite relaxation deficiency factors Size, assess the moisture intrusion point of the oil-paper insulating sleeve; when the composite relaxation missing factor When the composite relaxation deficiency factor is less than 2.639566e+02, it indicates that the oil-paper insulating bushing has no moisture intrusion points; when the composite relaxation deficiency factor is less than 2.639566e+02... When the composite relaxation missing factor is less than 2.731890e+02, the flange is considered a point of moisture intrusion; when the composite relaxation missing factor is less than 2.731890e+02... When the composite relaxation loss factor is less than 2.763325e+02, it indicates that the general's hat is a point of moisture intrusion; when the composite relaxation loss factor is less than 2.763325e+02... When the value is less than 5.467673e+02, it indicates that the ceramic layer is a point of moisture intrusion; when the composite relaxation deficiency factor is less than 5.467673e+02, it indicates that the ceramic layer is a point of moisture intrusion. When the value is >5.467673e+02, it represents a point of global moisture intrusion.

[0018] The present invention also provides an assessment system for moisture intrusion points of oil-paper insulating sleeves, including a processor, a memory and a bus, wherein the memory stores machine-readable instructions executed by the processor;

[0019] When the system is running, the processor and the memory communicate via a bus, and the machine-readable instructions are executed by the processor as described in the method for assessing the moisture intrusion point of an oil-paper insulating sleeve.

[0020] The advantages of this invention are:

[0021] This invention provides a method for assessing moisture intrusion points in oil-paper insulating sleeves. It uses dielectric loss data to plot frequency-dielectric loss data curves, proposes relaxation offset factors and high-frequency gap factors based on the curve images, and constructs a composite relaxation missing factor. This method enables accurate identification of moisture intrusion point types in oil-paper insulating sleeves and provides a way to assess moisture intrusion points in oil-paper insulating sleeves. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart of a method for assessing the moisture intrusion point of an oil-paper insulating sleeve according to a preferred embodiment of the present invention. Detailed Implementation

[0023] The invention will now be described in further detail with reference to the accompanying drawings:

[0024] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0026] Figure 1 The diagram shows a flowchart of a method for assessing moisture intrusion points in oil-paper insulating sleeves. Figure 1 It can be seen that the assessment method for moisture intrusion points in oil-paper insulating sleeves mainly includes the following steps:

[0027] Step 1: Offline static treatment of sleeves at different moisture intrusion points

[0028] Oil-paper insulating sleeves with different moisture intrusion points were prepared, namely, no moisture intrusion point, flange moisture intrusion point, upper ceramic moisture intrusion point, general cap moisture intrusion point, and global moisture intrusion point. They were placed in the same ambient temperature and left to stand for 24 hours.

[0029] Step 2: Acquiring dielectric loss data

[0030] Record the ambient temperature as T, in K, and perform dielectric loss tests on bushings at different moisture intrusion points within the range of 1 MHz to 1 kHz to obtain dielectric loss data;

[0031] Step 3: Plot the dielectric loss curve

[0032] The dielectric loss data obtained at different frequencies are connected sequentially according to the frequency magnitude to plot the dielectric loss curves at different moisture intrusion points.

[0033] Step 4: Determining the point of moisture intrusion

[0034] Based on the dielectric loss curve, the relaxation offset factor is calculated using formula (1). ;

[0035] (1)

[0036] In the formula, This represents the frequency corresponding to the lowest dielectric loss value at different intrusion points. The frequency corresponding to the lowest dielectric loss value without moisture intrusion points, in Hz;

[0037] Calculate the high-frequency gap factor using formula (2)

[0038] (2)

[0039] In the formula, This represents the dielectric loss value at a frequency of 1kHz, representing the point of global moisture intrusion. This represents the dielectric loss value for frequencies ranging from 1 MHz to 1 kHz, excluding 1 kHz. This represents the Heaviside step function, and N represents the number of frequency points in the range of 1 mHz to 1 kHz.

[0040] Calculate the composite relaxation missing factor using formula (3)

[0041] (3)

[0042] Through composite relaxation deficiency factors Size, assessment of moisture intrusion points in oil-paper insulating sleeves, composite relaxation defect factor A very small value indicates that the oil-paper insulating sleeve has no moisture intrusion points, and the composite relaxation deficiency factor is low. A small value indicates that the oil-paper insulating sleeve is the point of moisture intrusion into the flange, indicating a composite relaxation deficiency factor. A smaller value indicates that the oil-paper insulating sleeve is the point of moisture intrusion into the "General's Cap" (a type of insulating sleeve), indicating a composite relaxation deficiency factor. A high value indicates that the oil-paper insulating sleeve is the point of moisture intrusion into the upper ceramic layer, indicating a composite relaxation deficiency factor. The highest value indicates that the oil-paper insulating sleeve is the point of global moisture intrusion.

[0043] Specifically, when the composite relaxation missing factor When the composite relaxation deficiency factor is less than 2.639566e+02, it indicates that the oil-paper insulating bushing has no moisture intrusion points; when the composite relaxation deficiency factor is less than 2.639566e+02... When the composite relaxation missing factor is less than 2.731890e+02, the flange is considered a point of moisture intrusion; when the composite relaxation missing factor is less than 2.731890e+02... When the composite relaxation loss factor is less than 2.763325e+02, it indicates that the general's hat is a point of moisture intrusion; when the composite relaxation loss factor is less than 2.763325e+02... When the value is less than 5.467673e+02, it indicates that the ceramic layer is a point of moisture intrusion; when the composite relaxation deficiency factor is less than 5.467673e+02, it indicates that the ceramic layer is a point of moisture intrusion. When the value is >5.467673e+02, it represents a point of global moisture intrusion.

Claims

1. A method of assessing a moisture ingress point of an oil-paper insulated bushing, characterized in that, Comprising the following steps: Step 1: Prepare oil-paper insulation bushings with different moisture invasion points and place them in the same ambient temperature; the different moisture invasion points are no moisture invasion point, flange moisture invasion point, upper ceramic moisture invasion point, general cap moisture invasion point and global moisture invasion point; Step 2: Record the ambient temperature as T, unit K, and carry out dielectric loss test connection in the range of 1mHz to 1kHz for oil-paper insulation bushings with different moisture invasion points to obtain dielectric loss data; Step 3: Connect the dielectric loss data obtained at different frequencies in order according to the frequency size to draw the dielectric loss curve under different moisture invasion points; Step 4: Determine the moisture invasion point.

2. The method for evaluating a moisture intrusion point of an oil-paper insulation bushing according to claim 1, characterized in that, According to the medium loss curve, the relaxation offset factor is calculated by using formula (1) ; (1) In the formula, represents the frequency corresponding to the lowest dielectric loss value under different invasion points, represents the frequency corresponding to the lowest dielectric loss value under no moisture invasion point.

3. The method for evaluating a moisture intrusion point of an oil-paper insulation bushing according to claim 2, characterized in that, The high frequency notch factor is calculated using equation (2) (2) wherein, represents the dielectric loss value at the frequency point 1 kHz of the global moisture intrusion point, represents the dielectric loss value at the frequency point in the range of 1 mHz to 1 kHz, excluding 1 kHz, represents the Heaviside step function, N represents the number of frequency points in the range of 1 mHz to 1 kHz, and j represents the jth frequency point.

4. The method for evaluating a moisture intrusion point of an oil-paper insulation bushing according to claim 3, characterized in that, The complex relaxation deficiency factor is calculated using equation (3) (3) By composite relaxation loss factor Size, evaluate the oil-paper insulation bushing moisture invasion point; when the composite relaxation loss factor <2.639566e+02, represents the oil-paper insulation bushing is no moisture invasion point; when the composite relaxation loss factor 2.639566e+02 <2.731890e+02, represents the flange is a moisture invasion point; when the composite relaxation loss factor 2.731890e+02 <2.763325e+02, represents the general hat is a moisture invasion point; when the composite relaxation loss factor 2.763325e+02 <5.467673e+02, represents the upper ceramic is a moisture invasion point; when the composite relaxation loss factor >5.467673e+02, represents the global is a moisture invasion point.

5. An evaluation system for moisture invasion points of oil-paper insulation bushings, comprising a processor, a memory and a bus, wherein the memory stores machine readable instructions executed by the processor; characterized in that when the system is running, the processor communicates with the memory through the bus, and the machine readable instructions are executed by the processor to implement the evaluation method for moisture invasion points of oil-paper insulation bushings according to any one of claims 1 to 4. ​

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