Power cable terminal partial discharge detection method

Abstract

The invention belongs to the technical field of power cables, and particularly relates to a power cable terminal partial discharge detection method which comprises the following steps: step 1, preparation work; 2, selecting a proper probe and a proper instrument; step 3, installing a probe; 4, connecting and setting instruments; 5, initializing an instrument; 6, scanning a cable terminal; step 7, data acquisition and analysis; 8, judging and reporting a result; and 9, regular detection and maintenance are carried out, and the preparatory work is to ensure that all equipped instruments and equipment conform to related standards and specifications before the partial discharge detection is started. According to the invention, it can be ensured that instruments and equipment conform to standards and dirt on the surface of a terminal is removed; proper probes and instrument parameters are selected; the probes are installed and calibrated; the surface of the terminal is regularly scanned, professional software is used to analyze signals, discharge conditions are evaluated, reports are written, and regular detection and maintenance plan making are carried out to ensure safe operation of a power system.

Description

Technical Field

[0001] This invention belongs to the field of power cable technology, and specifically relates to a method for detecting partial discharge at power cable terminals. Background Technology

[0002] Power cable terminations, also known as cable heads or cable joints, are key components used to connect power cables to equipment or power networks. Their main function is to achieve a safe and reliable connection of the cable and to transmit electrical signals. Power cable terminations typically consist of the following components: Insulating sleeve: Wrapped around the cable, providing insulation and protection against power leakage and external interference; Terminal: The inner conductor of the cable is connected to the terminal inside the insulating sleeve by welding, crimping, or bolting to ensure current transmission; Insulator: Located at the top of the termination, the insulator supports the cable and isolates the insulating sleeve from the equipment or power network, preventing leakage and short circuits; Conductor: Used to connect the cable termination to the equipment or power network, ensuring smooth current transmission; Sealing material: Used to protect the internal components of the cable termination, preventing moisture, dust, and other external substances from entering and affecting the normal operation of the cable. Existing partial discharge detection methods for cable terminals generally only detect discharge at faulty cable terminals, failing to provide users with options for selecting appropriate probes and instrument parameters, and also failing to address surface contaminants at the terminals. Therefore, we propose a partial discharge detection method for power cable terminals to solve these problems. Summary of the Invention

[0003] The purpose of this invention is to provide a method for detecting partial discharge at power cable terminals. This method ensures that the instruments and equipment meet standards and that contaminants on the terminal surface are removed. It also allows for the selection of appropriate probes and instrument parameters, the installation and calibration of the probes, regular scanning of the terminal surface, analysis of signals using specialized software, evaluation of the discharge status, and the writing of reports. Regular testing and maintenance plans are then implemented to ensure the safe operation of the power system.

[0004] The specific technical solution adopted by this invention is as follows: A method for detecting partial discharge at a power cable terminal, the method comprising the following steps: Step 1. Preparation; Step 2. Select appropriate probes and instruments; Step 3. Install the probe; Step 4. Connect and set up the instrument; Step 5. Initialize the instrument; Step 6. Scan the cable termination; Step 7. Data collection and analysis; Step 8. Result Judgment and Reporting; Step 9. Regular inspection and maintenance.

[0005] In a preferred embodiment, the preparation work includes ensuring that all instruments and equipment comply with relevant standards and specifications before starting partial discharge detection, ensuring that all relevant equipment is in a safe state with no current flowing through it and no other interference, the relevant equipment including probes, cables, and terminal equipment, removing dust, contaminants and insulation from the terminal surfaces to ensure the accuracy of the detection, and ensuring that all safety measures have been taken, including wearing personal protective equipment and power-off measures.

[0006] In a preferred embodiment, selecting a suitable probe and instrument involves choosing a suitable probe type based on the characteristics of the cable type, voltage level, and terminal structure. The probe type can be one or more of contact probes, non-contact probes, multi-channel probes, and directional probes. Based on the characteristics of the cable and the frequency range of the discharge signal, a suitable partial discharge instrument with sufficient sensitivity and bandwidth is selected to effectively capture and analyze the partial discharge signal.

[0007] In a preferred embodiment, the installation of the probe involves selecting a suitable installation method based on the probe's installation requirements and the shape of the terminal to correctly install the probe onto the cable terminal, ensuring good contact with the terminal surface and avoiding air gaps to maximize signal reception. For terminals of different shapes, appropriate installation methods are used, such as clamping, sleeve, or magnetic probes.

[0008] In a preferred embodiment, the connection and setup of the instrument involves correctly connecting the partial discharge instrument to the probe, ensuring a secure connection, avoiding signal interference, and setting the instrument's gain, sensitivity, filter, amplification factor, and sampling rate parameters according to the instrument's operation manual.

[0009] In a preferred embodiment, the initialization instrument is used to perform instrument initialization settings and calibration, calibrate the zero point to eliminate background noise, adjust the gain to obtain a suitable signal strength, and perform sensitivity calibration according to the characteristics of the probe to ensure the accuracy and stability of the instrument.

[0010] In a preferred embodiment, the scanning of the cable terminal involves using a probe to perform a regular scan along the surface of the cable terminal to obtain the discharge status of the entire terminal surface. During the scan, uniform pressure and speed should be maintained, and care should be taken to ensure sufficient contact between the probe and the terminal.

[0011] In a preferred embodiment, the data acquisition and analysis involves the instrument converting the acquired partial discharge signal into a digital signal and recording it for subsequent analysis. Professional data analysis software is then used to perform time-domain analysis, frequency-domain analysis, and statistical analysis on the acquired signal to identify the discharge type, determine the location of the discharge source, and assess the characteristics and severity of the discharge activity.

[0012] In a preferred embodiment, the result judgment and report are based on the results of combined data analysis to assess and judge the partial discharge situation of the cable terminal, determine whether there is a partial discharge problem in the cable terminal, identify the location and severity of the discharge source, and compile a detailed inspection report, including the inspection results, the location and severity of the discharge source, and recommended repair measures. The periodic inspection and maintenance refers to regularly conducting partial discharge inspections of the cable terminal to detect and resolve potential problems as early as possible. After the inspection, a corresponding maintenance plan is formulated to promptly repair the detected problems and ensure the safe operation of the power system.

[0013] In a preferred embodiment, the contact probe includes a circular contact probe and a flat contact probe, and the non-contact probe includes a magnetic field probe and an infrared thermal imager. The circular contact probe is made of metal and has good mechanical stability. It directly contacts the surface of the cable terminal and is used for partial discharge detection inside the terminal box. The flat contact probe, also known as a planar contact probe, is made of metal or metal oxide material and has a large contact surface. It slides on the plane of the cable terminal to detect partial discharge activity on the terminal surface. The magnetic field probe detects partial discharge activity by measuring changes in the magnetic field near the terminal. The magnetic field probe consists of coils and non-contactly senses changes in the magnetic field generated by discharge activity on the terminal surface. The infrared thermal imager uses infrared radiation technology to determine partial discharge activity by detecting the heat distribution on the terminal surface. The infrared thermal imager displays the temperature distribution image of the terminal surface in real time, quickly identifying potential partial discharge problems. The multi-channel probe is a probe that simultaneously installs multiple sensors to detect partial discharge activity at different locations, improving detection efficiency. The directional probe has a special geometry and directionality to focus attention on a specific terminal area, improving the sensitivity of the discharge signal.

[0014] The technical effects achieved by this invention are as follows: Before starting the test, ensure that all instruments and equipment meet the relevant standards and specifications, and that all related equipment is in a safe condition. At the same time, remove dust, contaminants and insulation from the terminal surfaces to ensure the accuracy of the test. Based on the characteristics of cable type, voltage level and terminal structure, select the appropriate probe type and the appropriate instrument according to the frequency range of the discharge signal in order to effectively capture and analyze the partial discharge signal. Based on the probe's installation requirements and the shape of the terminal, select a suitable installation method to correctly install the probe on the cable terminal, ensuring good contact with the terminal surface and improving signal reception. Ensure the instrument and probe are correctly connected, and set the instrument parameters according to the operation manual, such as gain, sensitivity, filter, amplification factor, and sampling rate. Perform instrument initialization settings and calibration, zero-point calibration to eliminate background noise, gain adjustment to obtain appropriate signal strength, and sensitivity calibration to ensure instrument accuracy and stability; Use the probe to scan regularly along the surface of the cable terminal, maintaining uniform pressure and speed, and ensuring that the probe makes full contact with the terminal to obtain the discharge status of the entire terminal surface; The instrument converts the acquired partial discharge signals into digital signals and uses professional analysis software to perform time-domain analysis, frequency-domain analysis, and statistical analysis to comprehensively assess the characteristics and severity of discharge activity. Based on the data analysis results, accurately assess the partial discharge situation of the cable terminal and prepare a detailed inspection report, including the location of the discharge source, its severity, and recommended repair measures; Regular partial discharge detection should be conducted to identify and resolve potential problems early, and corresponding maintenance plans should be developed to ensure the safe operation of the power system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a partial discharge detection method for power cable terminals according to the present invention. Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Example

[0017] Please see Figure 1 As shown, the present invention provides a method for detecting partial discharge at a power cable terminal, the method comprising the following steps: Step 1. Preparation; Step 2. Select appropriate probes and instruments; Step 3. Install the probe; Step 4. Connect and set up the instrument; Step 5. Initialize the instrument; Step 6. Scan the cable termination; Step 7. Data collection and analysis; Step 8. Result Judgment and Reporting; Step 9. Regular inspection and maintenance; Preparation work includes ensuring that all instruments and equipment meet relevant standards and specifications before starting partial discharge detection, ensuring that all related equipment is in a safe state with no current flowing and no other interference, including probes, cables, and terminal equipment, and removing dust, contaminants, and insulation from the terminal surfaces to ensure the accuracy of the detection, and ensuring that all safety measures have been taken, including wearing personal protective equipment and power-off measures. Choosing the right probe and instrument involves selecting the appropriate probe type based on the cable type, voltage level, and terminal structure characteristics. The probe type can be a non-contact probe or a directional probe. Based on the cable characteristics and the frequency range of the discharge signal, a suitable partial discharge instrument with sufficient sensitivity and bandwidth should be selected to effectively capture and analyze the partial discharge signal. To install the probe, select the appropriate installation method based on the probe's installation requirements and the shape of the terminal. Correctly install the probe on the cable terminal, ensuring good contact with the terminal surface and avoiding air gaps to maximize signal reception. For different terminal shapes, use appropriate installation methods, such as clamping, sleeve, or magnetic probes. Connecting and setting up the instrument: To correctly connect the partial discharge instrument to the probe, ensure a secure connection and avoid signal interference, and set the instrument's gain, sensitivity, filter, amplification factor, and sampling rate parameters according to the instrument's operation manual; Initializing the instrument involves setting up and calibrating the instrument, calibrating the zero point to eliminate background noise, adjusting the gain to obtain a suitable signal strength, and calibrating the sensitivity according to the characteristics of the probe to ensure the accuracy and stability of the instrument. Scanning cable terminals involves using a probe to regularly scan the surface of the cable terminal to obtain the discharge status of the entire terminal surface. During scanning, uniform pressure and speed should be maintained, and care should be taken to ensure full contact between the probe and the terminal. Data acquisition and analysis involves the instrument converting the acquired partial discharge signals into digital signals and recording them for subsequent analysis. Professional data analysis software is used to perform time-domain analysis, frequency-domain analysis, and statistical analysis on the acquired signals to identify the discharge type, determine the location of the discharge source, and assess the characteristics and severity of the discharge activity. The results judgment and report are based on the data analysis results, to assess and judge the partial discharge situation of the cable terminal, to determine whether there is a partial discharge problem in the cable terminal, to determine the location and severity of the discharge source, and to write a detailed test report, including the test results, the location and severity of the discharge source, and the recommended repair measures. Regular inspection and maintenance involves regularly inspecting the cable terminal for partial discharge in order to detect and resolve potential problems as early as possible. After the inspection, an appropriate maintenance plan is developed to repair the detected problems in a timely manner to ensure the safe operation of the power system. Contact probes include circular contact probes and flat contact probes, while non-contact probes include magnetic field probes and infrared thermal imagers. Circular contact probes are made of metal and have good mechanical stability. They directly contact the surface of the cable terminal and are used for partial discharge detection inside the terminal box. Flat contact probes, also known as planar contact probes, are made of metal or metal oxide materials and have a large contact surface. They slide on the plane of the cable terminal to detect partial discharge activity on the terminal surface. Magnetic field probes detect partial discharge activity by measuring changes in the magnetic field near the terminal. Magnetic field probes consist of coils that non-contactly sense changes in the magnetic field generated by discharge activity on the terminal surface. Infrared thermal imagers utilize infrared radiation technology to determine partial discharge activity by detecting the heat distribution on the terminal surface. Infrared thermal imagers display real-time images of the temperature distribution on the terminal surface, quickly identifying potential partial discharge problems. Multi-channel probes are probes that simultaneously install multiple sensors to detect partial discharge activity at different locations, improving detection efficiency. Directional probes have special geometric shapes and orientations to focus attention on specific terminal areas, improving the sensitivity of discharge signals. Example

[0018] Please see Figure 1 As shown, the present invention provides a method for detecting partial discharge at a power cable terminal, the method comprising the following steps: Step 1. Preparation; Step 2. Select appropriate probes and instruments; Step 3. Install the probe; Step 4. Connect and set up the instrument; Step 5. Initialize the instrument; Step 6. Scan the cable termination; Step 7. Data collection and analysis; Step 8. Result Judgment and Reporting; Step 9. Regular inspection and maintenance; Preparation work includes ensuring that all instruments and equipment meet relevant standards and specifications before starting partial discharge detection, ensuring that all related equipment is in a safe state with no current flowing and no other interference, including probes, cables, and terminal equipment, and removing dust, contaminants, and insulation from the terminal surfaces to ensure the accuracy of the detection, and ensuring that all safety measures have been taken, including wearing personal protective equipment and power-off measures. Choosing the right probe and instrument involves selecting the appropriate probe type based on the cable type, voltage level, and terminal structure characteristics. The probe type can be a contact probe or a multi-channel probe. Based on the cable characteristics and the frequency range of the discharge signal, a suitable partial discharge instrument with sufficient sensitivity and bandwidth should be selected to effectively capture and analyze the partial discharge signal. To install the probe, select the appropriate installation method based on the probe's installation requirements and the shape of the terminal. Correctly install the probe on the cable terminal, ensuring good contact with the terminal surface and avoiding air gaps to maximize signal reception. For different terminal shapes, use appropriate installation methods, such as clamping, sleeve, or magnetic probes. Connecting and setting up the instrument: To correctly connect the partial discharge instrument to the probe, ensure a secure connection and avoid signal interference, and set the instrument's gain, sensitivity, filter, amplification factor, and sampling rate parameters according to the instrument's operation manual; Initializing the instrument involves setting up and calibrating the instrument, calibrating the zero point to eliminate background noise, adjusting the gain to obtain a suitable signal strength, and calibrating the sensitivity according to the characteristics of the probe to ensure the accuracy and stability of the instrument. Scanning cable terminals involves using a probe to regularly scan the surface of the cable terminal to obtain the discharge status of the entire terminal surface. During scanning, uniform pressure and speed should be maintained, and care should be taken to ensure full contact between the probe and the terminal. Data acquisition and analysis involves the instrument converting the acquired partial discharge signals into digital signals and recording them for subsequent analysis. Professional data analysis software is used to perform time-domain analysis, frequency-domain analysis, and statistical analysis on the acquired signals to identify the discharge type, determine the location of the discharge source, and assess the characteristics and severity of the discharge activity. The results judgment and report are based on the data analysis results, to assess and judge the partial discharge situation of the cable terminal, to determine whether there is a partial discharge problem in the cable terminal, to determine the location and severity of the discharge source, and to write a detailed test report, including the test results, the location and severity of the discharge source, and the recommended repair measures. Regular inspection and maintenance involves regularly inspecting the cable terminal for partial discharge in order to detect and resolve potential problems as early as possible. After the inspection, an appropriate maintenance plan is developed to repair the detected problems in a timely manner to ensure the safe operation of the power system. Contact probes include circular contact probes and flat contact probes, while non-contact probes include magnetic field probes and infrared thermal imagers. Circular contact probes are made of metal and have good mechanical stability. They directly contact the surface of the cable terminal and are used for partial discharge detection inside the terminal box. Flat contact probes, also known as planar contact probes, are made of metal or metal oxide materials and have a large contact surface. They slide on the plane of the cable terminal to detect partial discharge activity on the terminal surface. Magnetic field probes detect partial discharge activity by measuring changes in the magnetic field near the terminal. Magnetic field probes consist of coils that non-contactly sense changes in the magnetic field generated by discharge activity on the terminal surface. Infrared thermal imagers utilize infrared radiation technology to determine partial discharge activity by detecting the heat distribution on the terminal surface. Infrared thermal imagers display real-time images of the temperature distribution on the terminal surface, quickly identifying potential partial discharge problems. Multi-channel probes are probes that simultaneously install multiple sensors to detect partial discharge activity at different locations, improving detection efficiency. Directional probes have special geometric shapes and orientations to focus attention on specific terminal areas, improving the sensitivity of discharge signals.

[0019] In this invention, before starting the test, it is ensured that all instruments and equipment comply with relevant standards and specifications, and that all related equipment is in a safe state. Simultaneously, dust, contaminants, and insulation are removed from the terminal surface to ensure test accuracy. Based on the cable type, voltage level, and terminal structure characteristics, a suitable probe type is selected, and an appropriate instrument is chosen according to the discharge signal frequency range to effectively capture and analyze partial discharge signals. According to the probe's installation requirements and the terminal's shape, a suitable installation method is selected to correctly install the probe on the cable terminal, ensuring good contact with the terminal surface to improve signal reception. The instrument and probe are correctly connected, and instrument parameters, such as gain, sensitivity, filter, amplification factor, and sampling rate, are set according to the operation manual. Instrument initialization and calibration are performed. Zero-point calibration eliminates background noise, gain adjustment obtains appropriate signal strength, and sensitivity calibration ensures instrument accuracy and stability. The probe is used to scan regularly along the cable terminal surface, maintaining uniform pressure and speed, and ensuring full contact between the probe and the terminal to acquire the discharge status of the entire terminal surface. The instrument converts the acquired partial discharge signals into digital signals and uses professional analysis software for time-domain, frequency-domain, and statistical analysis to comprehensively assess the characteristics and severity of discharge activity. Based on the data analysis results, the partial discharge status of the cable terminal is accurately assessed, and a detailed inspection report is prepared, including the location and severity of the discharge source and recommended remedial measures. Regular partial discharge detection is conducted to identify and resolve potential problems early and to develop corresponding maintenance plans to ensure the safe operation of the power system.

[0020] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A method for detecting partial discharge at the termination of a power cable, characterized in that: The detection method includes the following steps: Step 1. Preparation; Step 2. Select appropriate probes and instruments; Step 3. Install the probe; Step 4. Connect and set up the instrument; Step 5. Initialize the instrument; Step 6. Scan the cable termination; Step 7. Data collection and analysis; Step 8. Result Judgment and Reporting; Step 9. Regular inspection and maintenance.

2. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The preparation work includes ensuring that all instruments and equipment meet relevant standards and specifications before starting partial discharge detection, ensuring that all related equipment is in a safe state with no current flowing through it and no other interference. The related equipment includes probes, cables, and terminal equipment. Dust, contaminants, and insulation on the terminal surfaces should be removed to ensure the accuracy of the detection. All safety measures should be taken, including wearing personal protective equipment and power-off measures.

3. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The selection of appropriate probes and instruments involves choosing a suitable probe type based on the characteristics of the cable type, voltage level, and terminal structure. The probe type can be one or more of contact probes, non-contact probes, multi-channel probes, and directional probes. Based on the characteristics of the cable and the frequency range of the discharge signal, a suitable partial discharge instrument with sufficient sensitivity and bandwidth is selected to effectively capture and analyze the partial discharge signal.

4. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The installation of the probe involves selecting an appropriate installation method based on the probe's installation requirements and the shape of the terminal to correctly install the probe on the cable terminal, ensuring good contact with the terminal surface and avoiding air gaps to maximize signal reception. For terminals of different shapes, appropriate installation methods are used, such as clamping, sleeve, or magnetic probes.

5. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The connection and setup of the instrument involves correctly connecting the partial discharge instrument to the probe, ensuring a secure connection, avoiding signal interference, and setting the instrument's gain, sensitivity, filter, amplification factor, and sampling rate parameters according to the instrument's operation manual.

6. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The initialization instrument is used to initialize and calibrate the instrument, calibrate the zero point to eliminate background noise, adjust the gain to obtain a suitable signal strength, and perform sensitivity calibration according to the characteristics of the probe to ensure the accuracy and stability of the instrument.

7. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The scanning of the cable terminal involves using a probe to scan the surface of the cable terminal in a regular manner to obtain the discharge status of the entire terminal surface. During scanning, uniform pressure and speed should be maintained, and care should be taken to ensure full contact between the probe and the terminal.

8. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The data acquisition and analysis process involves the instrument converting the acquired partial discharge signals into digital signals and recording them for subsequent analysis. Professional data analysis software is used to perform time-domain analysis, frequency-domain analysis, and statistical analysis on the acquired signals to identify the discharge type, determine the location of the discharge source, and assess the characteristics and severity of the discharge activity.

9. The method for detecting partial discharge at a power cable terminal according to claim 1, characterized in that: The results judgment and report are based on the results of data analysis, assessing and judging the partial discharge situation of the cable terminal, determining whether there is a partial discharge problem in the cable terminal, identifying the location and severity of the discharge source, and compiling a detailed inspection report, including the inspection results, the location and severity of the discharge source, and recommended repair measures. The regular inspection and maintenance refers to regularly conducting partial discharge inspections of the cable terminal to detect and resolve potential problems as early as possible. After the inspection, a corresponding maintenance plan is formulated to promptly repair the detected problems and ensure the safe operation of the power system.

10. A method for detecting partial discharge at a power cable terminal according to claim 3, characterized in that: The contact probes include circular contact probes and flat contact probes, while the non-contact probes include magnetic field probes and infrared thermal imagers. The circular contact probes are made of metal, possessing good mechanical stability, and directly contact the surface of the cable terminal for partial discharge detection within the terminal box. The flat contact probes, also known as planar contact probes, are made of metal or metal oxide materials, have a large contact surface, and slide on the plane of the cable terminal to detect partial discharge activity on the terminal surface. The magnetic field probes detect partial discharge activity by measuring changes in the magnetic field near the terminal. The magnetic field probes consist of coils that non-contactly sense changes in the magnetic field generated by discharge activity on the terminal surface. The infrared thermal imager utilizes infrared radiation technology to determine partial discharge activity by detecting the heat distribution on the terminal surface. The infrared thermal imager displays a real-time image of the temperature distribution on the terminal surface, quickly identifying potential partial discharge problems. The multi-channel probes are probes that simultaneously install multiple sensors to detect partial discharge activity at different locations, improving detection efficiency. The directional probes have a special geometry and directionality, focusing attention on a specific terminal area and improving the sensitivity of the discharge signal.

Images