CN114895154A

CN114895154A - Composite insulator interface aging degree evaluation method

Info

Publication number: CN114895154A
Application number: CN202210390115.0A
Authority: CN
Inventors: 谢敏; 李晓刚; 刘祝鸿; 赵晨龙; 杨代铭
Original assignee: Research Institute Of Tsinghua Pearl River Delta
Current assignee: Research Institute Of Tsinghua Pearl River Delta
Priority date: 2022-04-14
Filing date: 2022-04-14
Publication date: 2022-08-12

Abstract

The invention discloses a method for evaluating the interface aging degree of a composite insulator, which comprises the following steps: obtaining a composite insulator sample; sequentially obtaining composite insulators from a composite insulator sample to be used as a sample to be intercepted, and intercepting a thin sheet at a preset position of the sample to be intercepted to be used as a sample to be detected; placing the sample to be tested in a first container and boiling in water for a first preset time; taking out the sample to be tested after being boiled in water, and placing the sample in a second container for cooling, wherein the water temperature in the second container is equal to the room temperature; determining that the temperature of the sample to be tested is cooled to room temperature, and drying the sample to be tested; measuring the leakage current of the dried sample to be tested; and classifying the aging degree of the composite insulator sample according to the measured leakage current. The aging degree of each composite insulator sample can be quantitatively given according to the classification result. The invention can be applied to the technical field of external insulation of high-voltage wires.

Description

Composite insulator interface aging degree evaluation method

Technical Field

The invention relates to the technical field of external insulation of high-voltage wires, in particular to a method for evaluating the interface aging degree of a composite insulator.

Background

In the related technology, the composite insulator is used as one of three most widely applied insulator types in the high-voltage overhead transmission line, and has the characteristics of easiness in processing, low cost and convenience in installation and transportation. In the application process of the composite insulator, the interface aging of the composite insulator is closely related to the interface breakdown of the insulator and the brittle failure of the core rod, and the operation safety of a power transmission line is directly related. At present, for the problem of interface aging of the composite insulator, methods such as interface tearing, nondestructive testing and ultrasonic wave are usually adopted to represent an aged interface, but the methods can only directly and simply represent the aged interface and cannot give a quantitative evaluation to the interface aging degree, so that the operation safety of a power transmission line cannot be improved.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a method for evaluating the interface aging degree of a composite insulator, which can quantitatively evaluate the interface aging degree of the composite insulator.

The embodiment of the invention provides a method for evaluating the interface aging degree of a composite insulator, which comprises the following steps:

obtaining a composite insulator sample, wherein the composite insulator sample comprises a composite insulator which runs on a power transmission line for a preset period;

sequentially obtaining composite insulators from a composite insulator sample to be used as a sample to be intercepted, and intercepting a thin sheet at a preset position of the sample to be intercepted to be used as a sample to be detected;

placing the sample to be tested in a first container and boiling for a first preset time;

taking out the sample to be tested after being boiled, placing the sample in a second container for cooling, wherein the temperature of water in the second container is equal to the room temperature;

determining that the temperature of the sample to be tested is cooled to room temperature, and drying the sample to be tested;

measuring the leakage current of the dried sample to be tested;

and classifying the aging degree of the composite insulator sample according to the measured leakage current.

In some embodiments, the cutting a sheet of the preset position of the sample to be cut as the sample to be tested includes:

and intercepting the thin slices at the high-pressure end position, the low-pressure end position and the middle position of the sample to be intercepted as the sample to be detected.

In some embodiments, the sectioning the specimen into a high pressure end position, a low pressure end position and a middle position of the specimen to be sectioned, as the specimen to be tested, includes:

and respectively cutting sheets with the thickness of more than or equal to 6mm at the high-pressure end position, the low-pressure end position and the middle position of the sample to be cut out in a transverse cutting mode to be used as the sample to be detected.

In some embodiments, the placing the sample to be tested in a first container for a first preset length of time in a water boil comprises:

and putting the sample to be tested into a first container filled with boiling water to be boiled for a first preset time.

In some embodiments, the placing the sample to be tested in a first container with boiling water for a first preset time period comprises:

and placing the sample to be tested in a first container filled with boiling water for boiling for more than or equal to 800 hours.

In some embodiments, the drying the sample to be tested comprises:

and drying the sample to be tested for a second preset time, wherein the second preset time is more than or equal to 24 hours.

In some embodiments, the drying the sample to be tested for a second preset time period includes:

and drying the sample to be tested in an air drying mode, an oven mode or a filter paper mode for a second preset time.

In some embodiments, the classifying the degree of aging of the composite insulator sample according to the measured leakage current includes:

when the leakage current belongs to a first preset condition, determining that the composite insulator sample is a serious interface aging type, wherein the first preset condition comprises that the leakage current of one sample to be tested in the positions of the high-voltage end, the low-voltage end and the middle part is larger than a first preset current;

when the leakage current belongs to a second preset condition, determining that the composite insulator sample is of an interface unaged type, wherein the second preset condition comprises that the leakage currents of all samples to be tested at the high-voltage end position, the low-voltage end position and the middle position are all smaller than a second preset current;

and when the leakage current does not belong to the first preset condition and the second preset condition, determining that the composite insulator sample is not in the interface preliminary aging type.

In some embodiments, the cross-cutting comprises a laser cross-cutting or a spark cross-cutting.

In some embodiments, the composite insulator comprises a strain insulator, a suspension insulator, or a disc insulator.

The method for evaluating the interface aging degree of the composite insulator has the following beneficial effects:

in the embodiment, the sheet at the preset position is firstly intercepted from the composite insulator on the power transmission line after the operation for the preset period to serve as the sample to be tested, then the sample to be tested is subjected to boiling, cooling and drying in sequence, then the leakage current is measured, and then the aging degree of the composite insulator sample is classified according to the leakage current obtained through measurement, so that the aging degree of each composite insulator sample can be quantitatively given according to the classification result.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described with reference to the following figures and examples, in which:

fig. 1 is a flowchart of a method for evaluating the interface aging degree of a composite insulator according to an embodiment of the present invention;

FIG. 2 is a schematic view of a sample to be intercepted in accordance with an embodiment of the present invention;

FIG. 3 is a graph of leakage current versus time after a short period of drying for a sample of a silicone rubber composite insulator in accordance with an embodiment of the present invention;

FIG. 4 is a graph of leakage current versus time after 24 hours of drying for a sample of a silicone rubber composite insulator in accordance with an embodiment of the present invention;

FIG. 5 is a schematic view of a sample of a sheet according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a test result of a testing process according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and the above, below, exceeding, etc. are understood as excluding the present numbers, and the above, below, within, etc. are understood as including the present numbers. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Referring to fig. 1, an embodiment of the present invention provides a method for evaluating an interface aging degree of a composite insulator, including the following steps:

and 110, obtaining a composite insulator sample, wherein the composite insulator sample comprises a composite insulator which runs for a preset time on a power transmission line. Specifically, the composite insulator includes a strain insulator, a suspension insulator or a disc insulator. The composite insulator has been used for a certain period of time on a power transmission line, for example, for half a year, 1 year or 2 years.

And 120, sequentially obtaining the composite insulator from the composite insulator sample as a sample to be intercepted, and intercepting the thin sheet at the preset position of the sample to be intercepted as the sample to be detected.

In the embodiment of the application, the thin sheets at the high-voltage end position, the low-voltage end position and the middle position of the sample to be intercepted can be intercepted to serve as the sample to be tested, so that the influence of different voltages on the aging degree of the composite insulator can be analyzed. Furthermore, it is also possible to position the sample to be intercepted in a high-pressure end position, a low-pressure end position and a middle position, respectively, as shown in FIG. 2 by means of a transverse cuttingCutting thickness d of the sample to be cut ₁ And 6mm or more of thin sheet is used as a sample to be tested. The transverse cutting mode comprises a laser transverse cutting mode or an electric spark transverse cutting mode. In this embodiment, the target traverse mode may be selected according to actual situations.

Step 130, placing the sample to be tested in a first container and boiling for a first preset time.

In this embodiment, a volume of boiling water may be stored in a first container, and then the sample to be tested is placed in the first container containing boiling water and boiled in water for a first predetermined period of time. The preset time period may be 800h or more than 800 h. In the present embodiment, the leakage current value of the tape test sample is increased by boiling the tape test sample in water for 800h or more, thereby improving the accuracy of the detection result.

And 140, taking out the sample to be tested after being boiled in water, and placing the sample in a second container for cooling, wherein the temperature of water in the second container is equal to the room temperature.

And 150, determining that the temperature of the sample to be tested is cooled to room temperature, and drying the sample to be tested.

In the embodiment of the application, after the boiled sample to be tested is cooled to room temperature, the sample to be tested is dried in one of an air drying mode, an oven mode or a filter paper mode. Specifically, the drying time may be a second preset time period set in advance. The second preset time period may be 24 hours or more than 24 hours.

Specifically, since silicone rubber composite insulator samples with different boiling times have different leakage currents at different drying times in an indoor environment, the stability is also different. Specifically, as shown in fig. 3, leakage current and time curves of silicone rubber composite insulator samples with different boiling times after being dried in an indoor environment for a short time are shown. As can be seen from fig. 3, the measured leakage current value after the short-time drying fluctuates largely and is not a constant value. As shown in fig. 4, the leakage current and time curves measured after the silicone rubber composite insulator samples with different boiling times were dried in the indoor environment for 24 hours. As can be seen from fig. 4, the measured leakage current value substantially stabilized and fluctuated less with time after sufficient drying for 24 hours or more. Therefore, if the sample after boiling is not dried sufficiently, moisture remains at the interface of the composite insulator, and the current rapidly changes during the measurement of the leakage current due to the moisture remaining in the interface, and thus the sample cannot be stabilized, and an accurate leakage current value cannot be obtained. Only after the composite insulator is fully dried after being boiled in water, the residual moisture in the composite insulator sample is less, the water loss enters a stable and slow state, the measured leakage current value can tend to be relatively stable, and the relatively stable leakage current value can be measured.

And step 160, measuring the leakage current of the dried sample to be tested.

And 170, classifying the aging degree of the composite insulator sample according to the measured leakage current.

In the embodiment of the present application, the classification according to the leakage current may include, but is not limited to, the following steps:

when the leakage current belongs to a second preset condition, determining that the composite insulator sample is an interface unaged type, wherein the second preset condition comprises that the leakage currents of all samples to be tested at the high-voltage end position, the low-voltage end position and the middle position are all smaller than a second preset current;

For example, assume that the first predetermined current is 8mA and the second predetermined current is 1 mA. If one of the leakage current values of the high-voltage end, the low-voltage end and the middle sample of the composite insulator is more than 8mA, the composite insulator is in a severe interface aging type, and is recommended to be replaced immediately; if the leakage current values of the high-voltage end, the low-voltage end and the middle sample of the composite insulator sample are all below 1mA, classifying the composite insulator into an interface unaged type, and predicting that the composite insulator can run for more than 10 years; if the leakage current values of the high-voltage end, the low-voltage end and the middle sample of the composite insulator do not belong to the two conditions, the composite insulator is classified into an interface primary aging type, and important monitoring during operation is recommended.

In some embodiments, the evaluation methods of the above embodiments are applied to a test process, which specifically includes the following: the samples to be tested shown in FIG. 2 were thin samples of 3.5mm to 4mm thickness with the core rod 220-sheath 210 interface as shown in FIG. 5, and the thin samples were used in a shape of thin sheets to accelerate the aging process of the core rod-sheath interface, the sample diameter was 34mm, wherein the sheath thickness was 5mm, the core rod thickness was 24mm, the sample center had a small hole of 4mm diameter, and the small hole in the center was used for later proving that the change in leakage current is mainly caused by interface aging. In this example, a test was conducted using a common silicone rubber insulator sample and a cycloaliphatic epoxy resin insulator sample.

The samples are respectively placed in boiling water to be boiled for 1000h, in the embodiment, the samples are taken from brand-new insulators, so that the boiling time is long, the samples are taken out after being boiled for 1000h and placed in room-temperature water to be cooled to room temperature and dried, and leakage current measurement is carried out after drying. Leakage current through the sample includes current through the core rod, the interface region, the sheath, and the sheath surface, the core rod surface, and the central aperture surface. If the current passing through the core rod, the sheath and the surface of the sample does not change greatly before and after the water boiling, and only the current in the interface area changes greatly, the leakage current can reflect the aging state of the interface.

Based on this, the present embodiment first measures the leakage current of a sample comprising a complete core rod and sheath; then stripping the sheath from the core rod, and scraping the sheath on the surface of the core rod to ensure that only a trace of sheath is left on the surface of the core rod and the leakage current is measured; finally scraping a trace sheath thin layer on the side surface of the core rod, and measuring the leakage current again; further, the sheath peeled from the mandrel bar was also subjected to measurement of leakage current, and the measurement results of the above-described various leakage currents are shown in fig. 6. In fig. 6, the surface of the core rod still has a significant leakage current when the trace sheath remains, and after scraping off all the trace sheath remaining on the core rod, the leakage current value decreases to less than 0.1mA, and since the scraping operation is not performed on the surface of the core rod at the central small hole of the sample, the leakage current value has already decreased to a level less than 0.1mA, which indicates that the leakage current is mainly caused by the core rod-sheath interface, the disappearance of the interface causes a steep drop in the leakage current, and the presence of the interface causes a steep rise in the leakage current. From the leakage current results of the individual sheaths, it can be seen that the leakage current of the undried silicone rubber sheath is less than 0.2mA, the leakage currents of the silicone rubber sheath and the epoxy sheath dried for 1 hour in an indoor environment are both less than 0.1mA, and it can be seen that the value of the leakage current through the individual sheath is much smaller than the value of the leakage current through the sheathed core rod, i.e., the leakage current of the sheathed core rod still mainly comes from the core rod-sheath interface.

As can be seen from the above test process, after the sample is aged, the leakage current passing through the core rod portion and the sheath portion is much smaller than the leakage current passing through the core rod-sheath assembly, and further the leakage current passing through the core rod-sheath assembly can be considered to be mainly composed of the leakage current passing through the core rod-sheath interface, and the magnitude of the leakage current at the interface is directly related to the interface aging.

In summary, the embodiment of the present application has the following beneficial effects:

the method has the advantages that firstly, quantitative characterization of the interface aging degree of the composite insulator can be realized, the interface aging degree of the composite insulator is reasonably classified according to quantifiable indexes, and the reliability of classification is improved;

the second point is that the embodiment improves the comprehensiveness of sampling by intercepting the samples of the three interfaces of the low-voltage end, the middle part and the high-voltage end, avoids omission of a local interface aging region, enables an evaluation result to be more objective and credible, determines the replacement criterion of the insulator according to the leakage current of any one of the three interface samples above 8mA, is safe and reliable, and effectively ensures the operation safety of the power transmission line; meanwhile, according to the recognized interface aging degree, workers can pay attention to different degrees and take measures of different degrees respectively, and resource waste is reduced.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.

Claims

1. A method for evaluating the interface aging degree of a composite insulator is characterized by comprising the following steps:

measuring the leakage current of the dried sample to be tested;

2. The method for evaluating the interface aging degree of the composite insulator according to claim 1, wherein the step of cutting the thin sheet at the preset position of the sample to be cut out as the sample to be tested comprises the following steps:

3. The method for evaluating the interface aging degree of the composite insulator according to claim 2, wherein the step of intercepting the thin sheets at the high-voltage end position, the low-voltage end position and the middle position of the sample to be intercepted as the sample to be tested comprises the following steps:

4. The method for evaluating the interface aging degree of the composite insulator according to claim 1, wherein the step of placing the sample to be tested in a first container and boiling for a first preset time comprises:

5. The method for evaluating the interface aging degree of the composite insulator according to claim 4, wherein the step of placing the sample to be tested in a first container filled with boiling water for boiling for a first preset time comprises the following steps:

6. The method for evaluating the interface aging degree of the composite insulator according to claim 1, wherein the step of drying the sample to be tested comprises the following steps:

7. The method for evaluating the interface aging degree of the composite insulator according to claim 6, wherein the drying the sample to be tested for the second preset time period comprises:

8. The method of claim 3, wherein the classifying the aging degree of the composite insulator sample according to the measured leakage current comprises:

9. The method for evaluating the interface aging degree of the composite insulator according to claim 3, wherein the transverse cutting mode comprises a laser transverse cutting mode or an electric spark transverse cutting mode.

10. The method as claimed in claim 1, wherein the composite insulator comprises a tension insulator, a suspension insulator or a disc insulator.