Method for evaluating insulation state of intermediate joint of high-voltage cable based on gas detection

Abstract

The invention relates to a high-voltage cable intermediate joint insulation state evaluation method based on gas detection, which is characterized in that a gas collection chamber is arranged in a sealant filling hole of a high-voltage cable intermediate joint, so that characteristic gas can be conveniently collected and extracted, and the gas collection chamber is used for collecting the characteristic gas generated in the high-voltage cable intermediate joint; the gas chromatograph is used for analyzing and detecting the collected characteristic gas, the standard sample is used for calibration, and the barometer is used for indicating the air pressure difference value between the air pressure in the gas collection chamber and the atmospheric pressure of the external environment. According to the invention, the components, the content and the air pressure difference value of the characteristic gas can be accurately and intuitively determined, and reliable data support is provided for evaluation of the insulation state. Therefore, compared with the existing live detection technology, the evaluation method provided by the invention is smaller in interference and more accurate in test result, and the characteristic gas can be stored in the gas collection chamber for a longer time, so that the insulation state of the intermediate joint can be effectively evaluated.

Description

Technical Field

[0001] The invention belongs to the technical field of cable evaluation, in particular to a method for evaluating the insulation state of a high-voltage cable intermediate joint based on gas detection. Background Art

[0002] At present, the intermediate joints of high-voltage cables are installed by construction personnel or manufacturers at the project site. The prefabricated insulation parts of cable joints have high requirements for environmental cleanliness, complex internal structures of joints, and difficult key process control. As a result, potential insulation defects such as impurities mixed in, installation size deviation, and unqualified insulation shielding fracture treatment often occur during the installation process of cable joints. Such defects are difficult to detect and highly concealed. Existing high-voltage cable live detection technologies, such as partial discharge detection, sheath circulation monitoring, and infrared temperature measurement, are not sensitive to common problems such as water ingress and early insulation defects. They have limitations such as low defect detection rate and large interference from electromagnetic environment. High-voltage cable joints still lack sensitive early defect detection and early warning technical means. Under the action of overheating, electrochemical corrosion, and partial discharge, high-voltage cable joints will release certain characteristic gases, such as methane, carbon monoxide, and some hydrocarbon gases. Such characteristic gas derivatives are closely related to the operating status of the cable joint. By analyzing key parameters such as characteristic gas components and concentrations, the degree and type of joint degradation can be diagnosed, providing a new idea for the accurate diagnosis of the status of the cable intermediate joint. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method for evaluating the insulation status of a high-voltage cable intermediate joint based on gas detection, which can solve the problem of poor accuracy in the evaluation method of the insulation status of a high-voltage cable intermediate joint in the prior art. Compared with the existing live detection technology, the evaluation method has less interference, more accurate test results, and is more convenient for effective evaluation of the insulation status of the intermediate joint.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] The method for evaluating the insulation status of a high-voltage cable intermediate joint based on gas detection comprises the following steps:

[0006] Step S1, constructing a gas extraction device, installing the constructed gas extraction device on the middle joint of the high-voltage cable, and using the gas extraction device to collect characteristic gas in the middle joint of the high-voltage cable online;

[0007] Step S2, using gas chromatography to detect the components of the characteristic gas obtained in step 1, and recording the response peak data including the appearance time, peak area and peak height of the response peak;

[0008] Step S3, using a standard sample of known concentration to calibrate the response peak data recorded in step 2 to determine the type and content of each component in the characteristic gas;

[0009] Step S4: Based on the type and content of the characteristic gas and the pressure difference determined in step 3, the insulation state of the intermediate joint of the high-voltage cable is evaluated.

[0010] Moreover, the gas extraction device in step 1 includes a gas collecting chamber, a mounting base, a barometer and a gas extraction valve, wherein the gas collecting chamber has a mounting base, and the gas collecting chamber is used to collect characteristic gases in the intermediate joint of the high-voltage cable online; the barometer is electrically connected to the gas collecting chamber, and the barometer is used to indicate the pressure difference between the air pressure in the gas collecting chamber and the atmospheric pressure of the external environment; the gas extraction valve is installed on the side wall of the gas collecting chamber and is used for the gas extraction device.

[0011] Moreover, the specific implementation method of installing the constructed air extraction device on the middle joint of the high-voltage cable in step 1 is: seamlessly connect the mounting base of the air extraction device with the sealant injection hole on the metal protective shell of the middle joint of the high-voltage cable, open the air extraction valve, and the air extraction device extracts air.

[0012] The advantages and positive effects of the present invention are:

[0013] The present invention installs a gas collecting chamber at the sealant injection hole of the middle joint of the high-voltage cable, so that characteristic gases can be easily collected and extracted, and the characteristic gases generated in the middle joint of the high-voltage cable are collected by using the gas collecting chamber, and the collected characteristic gases are analyzed and detected by using a gas chromatograph, and calibrated by using standard samples. The barometer is used to indicate the pressure difference between the air pressure in the gas collecting chamber and the atmospheric pressure of the external environment. The present invention can accurately and intuitively determine the composition, content and pressure difference of the characteristic gas, and provide reliable data support for the evaluation of the insulation status. Therefore, compared with the existing live detection technology, the evaluation method of the present invention has less interference, more accurate test results, and the characteristic gas can be stored in the gas collecting chamber for a longer time, thereby facilitating the effective evaluation of the insulation status of the middle joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of the gas extraction device for the middle joint of the high-voltage cable;

[0015] Figure 2 This is the installation diagram of the air extraction device for the middle joint of the high-voltage cable.

[0016] Description of labels:

[0017] 1-Gas collecting chamber; 2-Mounting base; 3-Barometer; 4-Gas extraction valve. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below with reference to the accompanying drawings.

[0019] The method for evaluating the insulation status of a high-voltage cable intermediate joint based on gas detection comprises the following steps:

[0020] Step S1, constructing a gas extraction device, installing the constructed gas extraction device on the middle joint of the high-voltage cable, and using the gas extraction device to collect characteristic gases in the middle joint of the high-voltage cable online.

[0021] like Figure 1 As shown, the gas extraction device in step 1 includes a gas collecting chamber 1, a mounting base 2, a barometer 3 and a gas extraction valve 4, wherein the gas collecting chamber has a mounting base, and the gas collecting chamber is used to collect characteristic gases in the intermediate joint of the high-voltage cable online; the barometer is electrically connected to the gas collecting chamber, and the barometer is used to indicate the pressure difference between the air pressure in the gas collecting chamber and the atmospheric pressure of the external environment, and the gas extraction valve is installed on the side wall of the gas collecting chamber and is used for the gas extraction device.

[0022] The specific implementation method of installing the constructed air extraction device on the middle joint of the high-voltage cable in step 1 is: seamlessly connect the installation base of the air extraction device with the sealant injection hole on the metal protective shell of the middle joint of the high-voltage cable, open the air extraction valve, and the air extraction device extracts air.

[0023] Step S2: using gas chromatography to detect the components of the characteristic gas obtained in step 1, and recording the response peak data including the appearance time, peak area and peak height of the response peak.

[0024] Step S3: Use a standard sample with known concentration to calibrate the response peak data recorded in step 2 to determine the type and content of each component in the characteristic gas.

[0025] Step S4: Based on the type and content of the characteristic gas and the pressure difference determined in step 3, the insulation state of the intermediate joint of the high-voltage cable is evaluated.

[0026] The present invention installs a gas collecting chamber at the sealant injection hole of the middle joint of the high-voltage cable, so that characteristic gases can be easily collected and extracted, and the characteristic gases generated in the middle joint of the high-voltage cable are collected by using the gas collecting chamber, and the collected characteristic gases are analyzed and detected by using a gas chromatograph, and calibrated by using standard samples. The barometer is used to indicate the pressure difference between the air pressure in the gas collecting chamber and the atmospheric pressure of the external environment. The present invention can accurately and intuitively determine the composition, content and pressure difference of the characteristic gas, and provide reliable data support for the evaluation of the insulation status. Therefore, compared with the existing live detection technology, the evaluation method of the present invention has less interference, more accurate test results, and the characteristic gas can be stored in the gas collecting chamber for a longer time, thereby facilitating the effective evaluation of the insulation status of the middle joint.

[0027] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the insulation status of a high-voltage cable intermediate joint based on gas detection, characterized in that: The following steps are involved: Step S1, constructing a gas extraction device, installing the constructed gas extraction device on the middle joint of the high-voltage cable, and using the gas extraction device to collect characteristic gas in the middle joint of the high-voltage cable online; Step S2, using gas chromatography to detect the components of the characteristic gas obtained in step 1, and recording the response peak data including the appearance time, peak area and peak height of the response peak; Step S3, using a standard sample of known concentration to calibrate the response peak data recorded in step 2 to determine the type and content of each component in the characteristic gas; Step S4: Based on the type and content of the characteristic gas and the pressure difference determined in step 3, the insulation state of the intermediate joint of the high-voltage cable is evaluated.

2. The method for evaluating the insulation status of a high-voltage cable intermediate joint based on gas detection according to claim 1 is characterized in that: The gas extraction device in step 1 includes a gas collecting chamber, a mounting base, a barometer and a gas extraction valve, wherein the gas collecting chamber has a mounting base, and the gas collecting chamber is used to collect characteristic gases in the intermediate joint of the high-voltage cable online; the barometer is electrically connected to the gas collecting chamber, and the barometer is used to indicate the pressure difference between the air pressure in the gas collecting chamber and the atmospheric pressure of the external environment; the gas extraction valve is installed on the side wall of the gas collecting chamber and is used for the gas extraction device.

3. The method for evaluating the insulation status of a high-voltage cable intermediate joint based on gas detection according to claim 2 is characterized in that: The specific implementation method of installing the constructed air extraction device on the middle joint of the high-voltage cable in step 1 is: seamlessly connect the installation base of the air extraction device with the sealant injection hole on the metal protective shell of the middle joint of the high-voltage cable, open the air extraction valve, and the air extraction device extracts air.

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