A method for testing the high-pressure sleeve electric heating aging characteristics of impregnated paper

Abstract

The application discloses a kind of impregnated paper high-pressure bushing electric heat aging characteristic test methods, applied to aging characteristic test device;The device includes: impregnated paper bushing and heating rod;The method comprises the following steps: adjusting heating rod temperature is preset temperature value and is impregnated paper bushing and power on;After preset aging time, measure the characteristics of impregnated paper bushing and obtain multiple characteristic values according to preset time interval;Characteristic value includes: partial discharge amount, dielectric constant and high voltage dielectric loss value;According to multiple partial discharge amount, the change rule of partial discharge spectrogram along with aging time is obtained;According to multiple dielectric constant and high voltage dielectric loss value, the change rule of frequency domain dielectric spectrum data along with aging time is obtained.The partial discharge amount, dielectric constant and high voltage dielectric loss value can be measured, so that the fireworks rule of impregnated paper bushing before insulation breakdown can be more fully and detailedly understood, and the change condition of the insulation state of impregnated paper bushing during the process of electric heat aging is analyzed.

Description

Technical Field

[0001] This application relates to the field of high-voltage bushing characteristic testing technology, and in particular to a method for testing the electrothermal aging characteristics of adhesive-impregnated paper high-voltage bushings. Background Technology

[0002] High-voltage bushings are used in power transmission and transformation projects to allow current-carrying conductors to pass through metal enclosures or valve hall walls of equipment at different potentials, introducing or extracting full voltage and current, and serving as insulation and mechanical support. Due to their explosion-proof, flame-retardant, small size, and light weight, impregnated paper high-voltage bushings are widely used in power grid construction. However, in practical applications, impregnated paper high-voltage bushings are affected by multiple factors such as electricity and heat; therefore, it is necessary to study their aging characteristics.

[0003] Existing tests on the electrothermal aging characteristics of paper-impregnated bushings often only measure the current, voltage, and conductivity of the bushing, which cannot adequately reflect the insulation state of the paper-impregnated bushing after electrothermal aging. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a method for testing the electrothermal aging characteristics of paper-impregnated high-voltage bushings, in order to solve the problem that existing tests for the electrothermal aging characteristics of paper-impregnated bushings cannot adequately reflect the insulation state of the paper-impregnated bushings after electrothermal aging.

[0005] To achieve the above technical objectives, this application provides a method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings, which is applied to an aging characteristic testing device;

[0006] The device includes: a paper-impregnated sleeve and a heating rod;

[0007] The adhesive-impregnated paper sleeve has a hollow cavity in the middle.

[0008] The heating rod is disposed inside the hollow cavity, and its outer periphery is in contact with the hollow cavity;

[0009] The method includes the following steps:

[0010] Adjust the temperature of the heating rod to the preset temperature value and power on the impregnated paper sleeve;

[0011] After a preset aging time, multiple characteristic values ​​are obtained by measuring the properties of the resin-impregnated paper sleeve at preset time intervals.

[0012] The characteristic values ​​include: partial discharge quantity, dielectric constant, and high voltage dielectric loss value;

[0013] The variation pattern of partial discharge spectrum with aging time was obtained based on multiple partial discharge quantities.

[0014] Based on the aforementioned dielectric constants and high voltage dielectric loss values, the variation law of frequency domain dielectric spectrum data with aging time was obtained.

[0015] Furthermore, the impregnated paper sleeve includes an electrolyte epoxy resin layer and an electrolyte insulating paper layer;

[0016] The formula for calculating the high-voltage dielectric loss value is as follows:

[0017]

[0018] Where R = R1 + R2,

[0019] In the formula: tanδ is the high voltage dielectric loss value, R1 is the equivalent resistance value of the dielectric epoxy resin layer, R2 is the equivalent resistance value of the dielectric insulating paper, C1 is the equivalent capacitance value of the dielectric epoxy resin layer, C2 is the equivalent capacitance value of the dielectric insulating paper, C∞ is the initial equivalent capacitance value of the impregnated paper sleeve, and ω is the angular frequency of the alternating electric field.

[0020] Furthermore, the preset temperature value is 130°C.

[0021] Furthermore, the preset time interval is 24 hours.

[0022] Furthermore, before adjusting the temperature of the heating rod to a preset temperature value and energizing the impregnated paper sleeve, the process further includes:

[0023] The impregnated paper sleeve is subjected to a drying pretreatment.

[0024] Furthermore, the aging characteristic testing device also includes a housing and a gas cylinder;

[0025] The box is equipped with a sealed cavity;

[0026] The adhesive-impregnated paper sleeve is disposed within the sealed cavity;

[0027] The gas cylinder is connected to the sealed cavity via a valve and is used to store SF6 gas.

[0028] As can be seen from the above technical solution, this application provides a method for testing the electrothermal aging characteristics of a paper-impregnated high-voltage bushing, applied to an aging characteristic testing device. The device includes a paper-impregnated bushing and a heating rod. A hollow cavity is provided in the middle of the paper-impregnated bushing. The heating rod is disposed within the hollow cavity, and its outer periphery is in contact with the hollow cavity. The method includes the following steps: adjusting the temperature of the heating rod to a preset temperature value and energizing the paper-impregnated bushing; after a preset aging time, measuring multiple characteristic values ​​of the paper-impregnated bushing at preset time intervals; the characteristic values ​​include: partial discharge quantity, dielectric constant, and high-voltage dielectric loss value; obtaining the variation law of the partial discharge spectrum with aging time based on the multiple partial discharge quantities; obtaining the variation law of the frequency domain dielectric spectrum data with aging time based on the multiple dielectric constants and high-voltage dielectric loss values. By measuring the partial discharge quantity, dielectric constant, and high-voltage dielectric loss value, a more comprehensive and detailed understanding of the electrical characteristics of the paper-impregnated bushing before insulation breakdown can be achieved, and the changes in the insulation state of the paper-impregnated bushing during electrothermal aging can be analyzed. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the aging characteristic testing device used in a method for testing the electrothermal aging characteristics of a high-voltage sleeve impregnated with adhesive paper, as provided in an embodiment of this application. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0032] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a replaceable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0034] Please see Figure 1 This application provides a method for testing the electrothermal aging characteristics of a high-pressure sleeving tube with impregnated paper, which is applied to an aging characteristic testing device. The device includes an impregnated paper sleeving tube 1 and a heating rod 32. A hollow cavity 11 is provided in the middle of the impregnated paper sleeving tube 1. The heating rod 32 is disposed in the hollow cavity 11 and its outer periphery is attached to the hollow cavity 11.

[0035] The aging characteristic testing device may further include: a chamber 2, a temperature controller 31, a pressure control assembly 4, and an oil tank 7. A sealed cavity 21 may be provided inside the chamber 2. The impregnated paper sleeve 1 is fixed to the chamber 2, with its bottom end extending into the sealed cavity 21 and connected to the ground wire, and its top end equipped with a conduit 12. The conduit 12 is connected to a high-voltage power supply 5 through a protective resistor 6. The heating rod 32 and the temperature controller 31 form the temperature control assembly 3. The temperature controller 31 is used to sense the temperature inside the sealed cavity 21 via a temperature sensor and to control the heating temperature of the heating rod 32. The pressure control assembly 4 includes a gas cylinder 42 and a pressure controller 42. The gas cylinder 41 is used to store SF6 gas and is connected to the sealed cavity 21 via a valve; the pressure controller 42 is electrically connected to the valve and is used to sense the gas pressure inside the sealed cavity 21 and to control the opening and closing of the valve. The oil tank 7 is connected to the sealed cavity 21 via an oil valve, allowing oil to be added to the sealed cavity 21 when the impregnated paper sleeve 1 needs to be placed in an oily environment. By filling with SF6 gas or transformer oil, the actual operating conditions are simulated while ensuring that the insulation performance does not experience dangerous discharge.

[0036] The cross-section of the impregnated paper sleeve 1 can be annular. Furthermore, the impregnated paper sleeve 1 can be composed of alternating layers of insulating paper and epoxy resin. The hollow cavity 11 provided for inserting the heating rod 32 ensures sufficient contact between the heating rod 32 and the impregnated paper sleeve 1.

[0037] The method includes the following steps:

[0038] S1. Adjust the temperature of heating rod 32 to the preset temperature value and power on the paper-impregnated sleeve 1, which means starting the electrothermal aging characteristic simulation.

[0039] After assembling the entire circuit of the impregnated paper sleeve 1 and connecting the vacuum pump to the pressure control component 4, the entire cavity is first evacuated to a vacuum state. Then, the valve connecting the gas cylinder 42 is opened to fill the sealed cavity 21 with SF6 gas. Similarly, when oil filling is required, the oil valve can be opened for oil filling.

[0040] S2. After a preset aging time, multiple characteristic values ​​are obtained by measuring the properties of the resin-impregnated paper sleeve 1 at preset time intervals; the characteristic values ​​include: partial discharge quantity, dielectric constant and high voltage dielectric loss value.

[0041] In the early stage of the electrothermal aging experiment, the electrical characteristics of the impregnated paper sleeve 1 change slowly, so the characteristic value measurement can be performed after a preset aging time. The preset aging time can be one month.

[0042] S3. Obtain the variation law of partial discharge spectrum with aging time based on multiple partial discharge quantities; obtain the variation law of frequency domain dielectric spectrum data with aging time based on multiple dielectric constants and high voltage dielectric loss values.

[0043] Specifically, regarding electrical insulation characteristics, when defects occur in the bushing during actual operation, burr defects will be generated inside. For these defects, data such as partial discharge and high voltage dielectric loss value can effectively monitor its insulation status.

[0044] Staff measured characteristic values ​​at preset time intervals until the paper-impregnated sleeve 1 was broken down. By observing the changes in the partial discharge spectrum and the frequency domain dielectric spectrum data with aging time, staff could clearly understand the evolution of the insulation of the paper-impregnated sleeve 1 before insulation breakdown, thus facilitating their understanding of the insulation state of the paper-impregnated sleeve after electrothermal aging.

[0045] The preset temperature value can be 130℃. Setting the preset temperature value to 130℃ can greatly accelerate the aging speed without changing the aging mechanism of the impregnated paper, while simulating the temperature gradient phenomenon caused by the heating at the 11 hollow cavities in actual operation.

[0046] The preset time interval is 24 hours.

[0047] As a further step, the method includes the following prior to step S1:

[0048] S0. Dry the glue-impregnated paper sleeve to avoid internal moisture interfering with the test results.

[0049] In practical applications, the impregnated paper sleeve 1 may include an electrolyte epoxy resin layer and an electrolyte insulating paper layer; let I1 and I2 correspond to the current values ​​of the electrolyte epoxy resin layer and the electrolyte insulating paper layer, respectively. According to the law of continuity of current, the current flowing through the two media is equal, i.e., I1 = I2. Therefore, the formula for calculating the loss current I under an alternating electric field is:

[0050]

[0051] Where R = R1 + R2,

[0052] In the formula, R1 is the equivalent resistance of the dielectric epoxy resin layer, R2 is the equivalent resistance of the dielectric insulating paper, C1 is the equivalent capacitance of the dielectric epoxy resin layer, and C2 is the equivalent capacitance of the dielectric insulating paper.

[0053] The formula for calculating the capacitive current component tanδ, which represents the high-voltage dielectric loss, is as follows:

[0054]

[0055] Wherein, C∞ is the initial equivalent capacitance of the impregnated paper sleeve, and ω is the angular frequency of the alternating electric field.

[0056] Then, when ω satisfies the following formula condition:

[0057]

[0058] The characteristic time constant corresponding to the loss peak in the curve of tanδ versus frequency f can be obtained as follows:

[0059]

[0060] Where d1 and d2 are the thicknesses of the electrolyte epoxy resin layer and the electrolyte insulating paper layer, respectively; γ1 and γ2 are the conductivity of the electrolyte epoxy resin layer and the electrolyte insulating paper layer, respectively; ε1 and ε2 are the relative permittivity of the electrolyte epoxy resin layer and the electrolyte insulating paper layer, respectively; and ε0 is the vacuum contact constant.

[0061] During the aging process of the paper-impregnated sleeve 1, the electrical conductivity of the material changes as electrothermal aging proceeds, thus altering the electrical conductivity of the paper-impregnated sleeve 1 and consequently changing its characteristic time constant. The change in the characteristic time constant can characterize the trend of electrical conductivity changes in the paper-impregnated sleeve 1 during the aging process, helping personnel to more comprehensively assess the changes in the insulation state of the paper-impregnated sleeve 1 during aging.

[0062] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings, characterized in that, Applications in aging characteristic testing equipment; The device includes: a housing, a gas cylinder, an oil tank, a paper-impregnated sleeve, and a heating rod; The box is equipped with a sealed cavity; The resin-impregnated paper sleeve is fixed to the box body, and the bottom end of the resin-impregnated paper sleeve extends into the sealed cavity and is connected to the ground wire. The top end of the resin-impregnated paper sleeve is provided with a conduit. The conduit is connected to a high-voltage power supply via a protective resistor; The gas cylinder is connected to the sealed cavity via a valve; The oil tank is connected to the sealed cavity via an oil valve; The impregnated paper sleeve has a hollow cavity in the middle; The heating rod is disposed inside the hollow cavity, and its outer periphery is in contact with the hollow cavity; The method includes the following steps: The sealed cavity is evacuated to a vacuum state, and the valve is opened to fill the sealed cavity with SF6 gas and the oil valve is opened to fill the sealed cavity with oil; Adjust the temperature of the heating rod to a preset temperature value and power on the impregnated paper sleeve; the preset temperature is 130°C. After a preset aging time, multiple characteristic values ​​are obtained by measuring the properties of the resin-impregnated paper sleeve at preset time intervals. The characteristic values ​​include: partial discharge quantity, dielectric constant, and high voltage dielectric loss value; The variation pattern of partial discharge spectrum with aging time was obtained based on multiple partial discharge quantities. Based on the aforementioned dielectric constants and high voltage dielectric loss values, the variation law of frequency domain dielectric spectrum data with aging time was obtained.

2. The method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings according to claim 1, characterized in that, The impregnated paper sleeve includes an electrolyte epoxy resin layer and an electrolyte insulating paper layer; The formula for calculating the high-voltage dielectric loss value is as follows: ； in, , , In the formula: R1 is the high voltage dielectric loss value, R2 is the equivalent resistance value of the dielectric epoxy resin layer, C1 is the equivalent capacitance value of the dielectric epoxy resin layer, C2 is the equivalent capacitance value of the dielectric insulating paper, C∞ is the initial equivalent capacitance value of the impregnated paper sleeve, and ω is the angular frequency of the alternating electric field.

3. The method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings according to claim 1, characterized in that, The preset temperature value is 130℃.

4. The method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings according to claim 1, characterized in that, The preset time interval is 24 hours.

5. The method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings according to claim 1, characterized in that, Before adjusting the temperature of the heating rod to a preset temperature value and energizing the impregnated paper sleeve, the following steps are also included: The impregnated paper sleeve is subjected to a drying pretreatment.

6. The method for testing the electrothermal aging characteristics of resin-impregnated paper high-voltage bushings according to claim 1, characterized in that, The aging characteristic testing device also includes a housing and a gas cylinder; The box is equipped with a sealed cavity; The adhesive-impregnated paper sleeve is disposed within the sealed cavity; The gas cylinder is connected to the sealed cavity via a valve and is used to store SF6 gas.

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