Online temperature intelligent early warning method for elbow-type plug of power cable

Abstract

The invention discloses a power cable elbow type plug on-line temperature intelligent early warning method, and relates to the field of on-line detection, and the method comprises the following steps: measuring the current of an elbow type plug, obtaining the heat generated by the elbow type plug based on the Joule law according to the current, obtaining the temperature variation according to the generated heat, and carrying out the early warning of the temperature of the elbow type plug. Calculating temperature data in combination with a preset initial temperature; the wavelength of the fiber bragg grating is measured, the environment temperature during operation of the elbow-type plug of the power cable is obtained, the temperature data obtained in real time is corrected by combining the wavelength change value and the temperature data, and a temperature compensation value is obtained; obtaining a safety margin, and obtaining a temperature early warning value in combination with the temperature compensation value; the temperature data and the temperature early warning value are compared and analyzed, and early warning prompt and maintenance work are given out in time according to the comparison and analysis result. According to the invention, the temperature change of the cable elbow-type plug can be monitored in real time, and an early warning signal is sent out in time, so that equipment damage or accidents caused by the temperature exceeding a safety range are avoided.

Description

Technical Field

[0001] The present invention relates to the field of online detection, and more specifically, to an intelligent online temperature early warning method for an elbow plug of a power cable. Background Art

[0002] Power cable elbow plugs use high-precision temperature sensors, such as thermocouples or thermistors, to monitor the surface or internal temperature of the equipment in real time. Sometimes they are also combined with position sensors to ensure the accuracy of the temperature monitoring location in the complex layout of power equipment. The temperature data collected by the sensor is collected in real time through an effective data acquisition system and transmitted to a centralized monitoring system or cloud server via a wired or wireless network to ensure the timeliness and integrity of the data. Some advanced early warning systems use machine learning algorithms to identify abnormal patterns or predict possible future temperature change trends by comparing historical data with real-time data.

[0003] Deficiencies of existing technologies: At present, the operation and maintenance personnel use the method of periodic offline detection of elbow-type plugs installed in the distribution network ring network cabinet by manually holding an ultrasonic partial discharge detector, or realizing online detection by sampling high-frequency induced voltage signals. Periodic offline detection of handheld partial discharge detectors: high cost, an ultrasonic partial discharge instrument costs tens of thousands of yuan; poor anti-interference ability, greatly affected by the external environment, such as the vibration of insect wings, footsteps and raindrops, etc., which can cause the instrument to move; strong limitations, can only detect ultrasonic signals, cannot detect electrical signals during partial discharge, and ultrasonic waves only appear in the late stage of the discharge process, so discharge defects cannot be discovered in time.

[0004] Therefore, the present invention proposes an intelligent online temperature early warning method for a power cable elbow plug to solve the above problem. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides an intelligent online temperature warning method for an elbow-type plug-in connector of a power cable, which solves the problems raised in the above-mentioned background technology by providing an intelligent online temperature warning method for an elbow-type plug-in connector of a power cable.

[0006] To achieve the above object, the present invention provides the following technical solutions: An intelligent early warning method for online temperature of a power cable elbow plug includes the following steps: Measure the current of the elbow plug, obtain the heat generated by the elbow plug based on Joule's law according to the current, obtain the temperature change according to the generated heat, and calculate the temperature data in combination with the preset initial temperature; measure the wavelength of the fiber grating, obtain the ambient temperature during the operation of the power cable elbow plug, and correct the real-time temperature data in combination with the wavelength change value and temperature data to obtain the temperature compensation value; obtain the safety margin, and obtain the temperature warning value in combination with the temperature compensation value, compare and analyze the temperature data with the temperature warning value, and issue early warning prompts and maintenance work in a timely manner according to the comparison and analysis results.

[0007] In a preferred embodiment, the method for obtaining the wavelength change value is as follows: measure the initial wavelength of the fiber grating and the heated wavelength after a certain time period; calculate the wavelength change value within a certain time period based on the initial wavelength and the heated wavelength combined with the preset optical fiber thermal expansion coefficient and thermo-optical coefficient.

[0008] In a preferred embodiment, the method for acquiring the temperature data of the elbow-type plug of the power cable is as follows: measure the current of the elbow-type plug, calculate the resistance value based on the measured current based on Ohm's law, and combine the current passage time to obtain the heat generated by the elbow-type plug based on Joule's law; combine the heat generated by the elbow-type plug with the mass and specific heat capacity of the elbow-type plug to obtain the temperature change; add the temperature change to the preset initial temperature to calculate the temperature data.

[0009] In a preferred embodiment, the method for obtaining the temperature compensation value is as follows: first, the ambient temperature during operation of the power cable elbow plug is obtained; combining the wavelength change value and the temperature data, the corrected measured temperature, i.e., the temperature compensation value, is calculated.

[0010] In a preferred embodiment, the method for obtaining the temperature warning value is as follows: obtaining the rated upper temperature limit of the plug connector, and calculating the difference between the rated upper temperature limit and the temperature data as a safety margin; The sum of the temperature compensation value and the safety margin is taken as the temperature warning value.

[0011] In a preferred embodiment, the temperature data is compared and analyzed with the temperature warning value, and the specific steps of timely issuing warning prompts and maintenance work are as follows: when the real-time temperature data is lower than the temperature warning value, there is no need to issue a warning, and continuous monitoring is carried out; when the real-time temperature data is higher than the temperature warning value, it is necessary to issue a warning in time and perform maintenance quickly.

[0012] The technical effects and advantages of the intelligent online temperature early warning method for the elbow plug of a power cable of the present invention are as follows: No changes to the original cable accessory structure: This method uses additional sensors for monitoring without modifying the original structure of the cable accessories. This non-invasive solution reduces interference with the equipment and the risk of potential failures, thereby ensuring the normal operation and long-term stability of the cable accessories. Real-time online monitoring: Advanced sensors and data acquisition systems can continuously monitor the temperature changes of the cable elbow plug. This real-time online monitoring can immediately detect abnormal conditions and take prompt measures to effectively avoid potential failures or safety hazards caused by excessive temperature. Direct measurement method: Compared with indirect measurement, direct measurement can obtain real temperature data more accurately. Direct measurement can avoid errors that may be introduced by indirect calculation and improve the accuracy and reliability of data; Intelligent automatic analysis: The system has the ability to automatically analyze and process data. It can not only automatically generate warnings, but also perform trend analysis based on temperature data. This allows operators, regardless of their technical level, to easily understand the system status, respond to warning information in a timely manner, and optimize maintenance strategies. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a structural schematic diagram of an intelligent early warning method for online temperature of a power cable elbow plug connector according to the present invention; Figure 2 It is a schematic diagram of the connection between the cable elbow plug and the ring network cabinet of the present invention. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] like Figure 2 As shown in the figure, the fully insulated cable elbow plug is a special device for connecting the cable to the ring main unit. The elbow plug is made of insulating rubber with good insulation. A shielded grounding wire is installed on the surface of the elbow. The other end of the shielded grounding wire is connected to the ground to confine the electric field force within the surface of the elbow. The cable terminal and the pile head inside the plug are fastened with bolts, and there is a small cavity around the crimping of the lower terminal.

[0015] Cable plug-in head heating can be divided into voltage heating type and current heating type; the current heating type is further divided into two types, one is that the conductor current increases, causing the temperature to rise, and the other is that the cable terminal and the bolt have poor contact, the resistance value increases, and then the temperature rises; the voltage heating type is due to the aging and damage of the insulation of the cable elbow plug-in head sheath, forming a conductive channel, which leads to the temperature rise. The current heating type generally has a large temperature change, and the temperature gets higher and higher as time goes by. On the contrary, the voltage heating type generally has a small temperature change, only a few degrees.

[0016] Figure 2 In the figure, 1 indicates a cabinet, 2 indicates a current transformer, 3 indicates an elbow plug, 4 indicates a temperature sensor, 5 indicates a cable compartment, and 6 indicates a shielded grounding wire. The current transformer 2 is installed at the port of the plug, and the temperature sensor is installed on the crimping terminal 7.

[0017] A cable has three phases. Three wireless cable thermometers are installed on the three crimping terminals of the cable respectively to monitor the temperature of each phase crimping terminal of the cable in real time, and then upload it to the back-end intelligent analysis system through a wireless transmitter. The current sensor is installed on the pile head of the cable compartment of the ring network cabinet to detect the size of the three-phase current in real time. The back-end intelligent analysis software analyzes and processes the data sent back by the temperature sensor and the current sensor, and compares it with the threshold set by the operation and maintenance personnel to draw a conclusion. When the system determines a fault, the operation and maintenance personnel are notified through the DTU early warning method.

[0018] This embodiment also provides an intelligent early warning method for online temperature of a power cable elbow plug, and the specific steps are as follows: S10, measuring the current of the elbow plug, obtaining the heat generated by the elbow plug based on the current based on Joule's law, obtaining the temperature change according to the generated heat, and calculating the temperature data in combination with the preset initial temperature; First, measure the current of the elbow plug to obtain a known voltage, and calculate the resistance value based on the measured current based on Ohm's law. The specific calculation formula is as follows:

[0019] Where U is the known voltage, It is the current measured at the elbow plug, and R is the resistance value; Then, combined with the current elapsed time, the heat generated by the elbow plug is obtained based on Joule's law; The specific calculation formula is as follows:

[0020] Where Q is the heat generated by the elbow plug, It is the current measured in the elbow plug, R is the resistance value, and t is the time when the current passes; The heat generated by the elbow plug is combined with the mass and specific heat capacity of the elbow plug to obtain a temperature change, and the temperature change is added to the preset initial temperature to calculate the temperature data; The specific calculation formula is as follows:

[0021] In the formula, is the temperature data, is the initial temperature, It is the heat generated by the elbow plug. is the quality of the elbow plug, is the specific heat capacity of the elbow plug; S20, measuring the wavelength of the fiber Bragg grating, obtaining the ambient temperature when the power cable elbow plug is in operation, and correcting the temperature data obtained in real time by combining the wavelength change value and the temperature data to obtain a temperature compensation value; The specific steps to measure the wavelength of fiber Bragg grating are as follows: Select appropriate light source and spectrometer to ensure that their wavelength range and resolution meet the measurement requirements; Connect the ends of the fiber Bragg grating to the light source and spectrometer respectively, making sure the connections are firm to prevent loss or interference of the optical signal; Start a light source, usually a laser diode or other suitable light source, to send an optical signal to the fiber grating sensor; Record reflected or transmitted light signals at specific wavelengths; The spectrometer scans these reflected or transmitted spectral lines and records the data on the variation of light intensity with wavelength.

[0022] Analyze the recorded reflection or transmission spectra using the data analysis software or tools provided with the spectrometer; Identify the main reflection or transmission peaks of the fiber Bragg grating, which correspond to the operating wavelength of the grating; Based on the analyzed data, determine the wavelength of the fiber Bragg grating sensor; usually this is done by identifying the location and intensity of the reflection or transmission peak; The initial wavelength and the heated wavelength of the fiber Bragg grating are measured by the above method; The obtained initial wavelength and heated wavelength are combined with the preset optical fiber thermal expansion coefficient and thermo-optical coefficient to calculate the wavelength change value within a certain time period. The specific calculation formula is as follows:

[0023] In the formula, is the wavelength change value, is the initial wavelength, is the heating wavelength, is the thermal expansion coefficient of the optical fiber, is the thermo-optical coefficient, It is the time cycle; In order to correct the measured temperature, considering the influence of the ambient temperature, the ambient temperature of the known power cable elbow plug and unplug operation is first obtained; The actual temperature after temperature correction, i.e., the temperature compensation value, is calculated by combining the wavelength change value and temperature data of the power cable elbow plug obtained in real time; The specific calculation formula of the temperature compensation value is as follows:

[0024] In the formula, is the temperature compensation value, is the temperature data, is the ambient temperature, is the known rate of temperature rise, is the wavelength change value; In the online temperature intelligent early warning of power cable elbow plugs, calculating the temperature compensation value is an important step, especially in combination with the ambient temperature and wavelength change value. The following are the effects and advantages of the temperature compensation value on the early warning system: Accurate Temperature Compensation: The ambient temperature has a significant impact on the temperature measurement of the power cable elbow plug. By acquiring the ambient temperature data in real time and combining it with the wavelength change value detected by the fiber grating sensor, the temperature compensation value can be accurately calculated to improve the accuracy and reliability of the early warning system. Improve the timeliness of early warning: Temperature compensation can effectively eliminate the influence of ambient temperature on sensor measurement. Therefore, even under greatly changing environmental conditions, the early warning system can still detect abnormal changes in the temperature of the power cable elbow plug in a timely and accurate manner, thereby providing early warning of potential equipment problems or failures. Enhance system stability and reliability: Through temperature compensation, the false alarm rate caused by environmental factors can be reduced, the system can operate more stably, and the feedback on equipment status is more reliable, which is crucial for the long-term stable operation and safety of power equipment; Refined data analysis: The temperature compensation value calculated in combination with the ambient temperature and wavelength change value can also be used by the system to conduct more in-depth data analysis and long-term trend monitoring. These data can help predict the life and performance degradation of equipment and further optimize equipment maintenance and operation plans. Intelligent decision support: The calculation of temperature compensation value is not only used for early warning system, but also provides a basis for intelligent decision support. For example, based on historical data and environmental changes, the system can automatically adjust the early warning threshold or provide operation suggestions to help operation and maintenance personnel manage the temperature and performance of power equipment more effectively. In summary, the temperature compensation value calculated in combination with the ambient temperature and wavelength change value not only improves the accuracy and timeliness of the early warning for the online temperature intelligent early warning system of the power cable elbow plug, but also enhances the stability and reliability of the system, providing important guarantee for the safe operation of power equipment.

[0025] S30, obtaining the rated temperature upper limit of the power cable elbow plug, combining the temperature data obtained in real time and the ambient temperature, calculating a safety margin, combining the safety margin with the temperature compensation value, and calculating a temperature warning value; The specific method for obtaining the temperature warning value is as follows: First, the difference between the acquired temperature data and the ambient temperature is calculated to obtain the temperature increment. Then, the rated temperature upper limit of the plug is obtained from the specification sheet or technical manual of the power cable elbow plug. The difference between the rated temperature upper limit and the temperature increment is calculated as the safety margin. The sum of the temperature compensation value and the safety margin is used as the temperature warning value. The specific calculation formula of the temperature warning value is as follows:

[0026] In the formula, is the temperature warning value, is the temperature compensation value, is the safety margin; The specific calculation formula of the safety margin is as follows:

[0027] In the formula, is the safety margin, is the upper temperature rating, is the temperature data; In the power cable system, elbow plugs play an important role. They connect cables and equipment and are key interface components in power transmission. Since the plugs will heat up due to the current load during operation, real-time monitoring and intelligent warning of their temperature are crucial to the safety and stability of the system. The important roles of temperature warning values ​​include: Prevent failures in advance: The temperature warning value can be set below the maximum safe operating temperature of the plug. Once the temperature of the plug exceeds the preset warning value, the system can immediately issue an alarm. This warning can help power maintenance personnel take timely measures to prevent equipment damage or failure caused by overheating of the plug. Protect equipment and personnel: Overheating of the plug head may cause aging and damage of the insulation material, or even cause a fire risk. By setting an appropriate temperature warning value, such safety problems can be effectively prevented and the safety of the equipment and working environment can be ensured. Optimize maintenance schedule: The temperature warning value not only helps to respond immediately when the temperature of the plug is abnormal, but also records and analyzes the temperature trend of the plug. This data can be used to optimize maintenance plans, such as determining whether it is necessary to add cooling equipment, improve the ventilation system, or adjust the cable load to avoid overheating; Extend equipment life: Timely temperature warning and response measures can effectively reduce the damage or performance degradation of the plug due to overheating, thereby extending its service life and reducing replacement costs and downtime; In summary, the temperature warning value plays a key role in the online temperature intelligent warning of the power cable elbow plug. Through real-time monitoring and timely response, it can effectively ensure the safe operation of the power system and the long-term stability of the equipment.

[0028] S40, comparing and analyzing the temperature data of the elbow plug of the power cable obtained in real time with the temperature warning value, and issuing warning prompts and maintenance work in time according to the comparison and analysis results.

[0029] Compare and analyze the real-time temperature data of the power cable elbow plug and unplug connector with the calculated temperature warning value; When the temperature data of the power cable elbow plug obtained in real time is lower than the temperature warning value, it is considered that the temperature of the plug is within the safe range and no warning is required. Continuous monitoring is continued to ensure continuous observation of temperature changes and prevent potential temperature rise problems. When the real-time temperature data of the power cable elbow plug is higher than the temperature warning value, it indicates that the temperature of the plug has exceeded the preset safety range, and an early warning is immediately issued to notify the relevant maintenance personnel or operators to quickly perform maintenance. At the same time, maintenance measures need to be taken quickly to reduce the temperature and prevent further thermal damage or equipment failure; Comparative analysis of the real-time temperature data of the power cable elbow plug and unplug connector and the set temperature warning value has the following important functions: Timely warning: Through comparative analysis, when the real-time temperature data exceeds the preset temperature warning value, the system can immediately issue a warning. This warning can be a visual alarm, an audible alarm, or a notification sent through an electronic information system, so that relevant personnel can take immediate action; Prevent accidents: Timely warning can help prevent safety accidents such as equipment damage, failure or even fire caused by overheating of the power cable elbow plug. By discovering temperature abnormalities in advance, necessary measures can be taken before the situation deteriorates. Quick response: Early warning prompts are not just about sounding an alarm, but more importantly, they can quickly start maintenance work, which may include suspending the use of equipment, adjusting the load, improving heat dissipation conditions, or directly inspecting and maintaining the plug connector. Through quick response, the temperature can be effectively reduced, reducing the risk of equipment running in a high temperature environment for a long time; Protecting equipment life: Regular maintenance and timely response to high temperature alarms can help protect the life of power cable elbow plugs and peripheral equipment. Excessive temperature may cause problems such as aging of insulation materials and damage to connector components. Maintenance work can extend the service life of equipment. Data recording and analysis: Continuous recording and analysis of temperature data helps identify possible trends and periodic patterns of equipment thermal problems. By analyzing historical data, the setting of temperature warning values ​​can be optimized to make it more consistent with actual usage conditions and equipment characteristics. Improve the early warning system: Based on the analysis results, the response speed and accuracy of the early warning system can be improved, further improving the safety and reliability of the system; By obtaining real-time temperature data and comparing the warning values, issuing warning prompts in a timely manner and performing maintenance work, the safety risks caused by temperature problems in the power system can be effectively reduced, and the stability and reliability of equipment operation can be ensured.

[0030] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0031] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product.

[0032] Those of ordinary skill in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0033] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0034] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0035] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent early warning method for online temperature of a power cable elbow plug, characterized in that: The following steps are involved: The current of the elbow plug is measured, the heat generated by the elbow plug is obtained based on the current and Joule's law, the temperature change is obtained based on the generated heat, and the temperature data is calculated in combination with the preset initial temperature; Measure the wavelength of the fiber Bragg grating to obtain the ambient temperature when the power cable elbow plug is in operation, and correct the real-time temperature data by combining the wavelength change value and temperature data to obtain the temperature compensation value; Obtain the safety margin, combine the temperature compensation value to obtain the temperature warning value, compare and analyze the temperature data with the temperature warning value, and issue early warning prompts and maintenance work in time according to the comparative analysis results.

2. According to claim 1, a method for intelligent online temperature early warning of a power cable elbow plug, characterized in that: The method for obtaining the wavelength change value is as follows: Measuring the initial wavelength of the fiber Bragg grating and the heated wavelength after a certain period of time; The wavelength change value within a certain time period is calculated based on the initial wavelength and the heated wavelength combined with the preset optical fiber thermal expansion coefficient and thermo-optical coefficient.

3. According to claim 1, a method for intelligent online temperature early warning of a power cable elbow plug, characterized in that: The method for obtaining the temperature data of the power cable elbow plug is as follows: The current of the elbow plug is measured, and the resistance value is calculated based on the measured current based on Ohm's law. The heat generated by the elbow plug is obtained based on Joule's law in combination with the time when the current passes; The temperature change is obtained by combining the heat generated by the elbow plug with the mass and specific heat capacity of the elbow plug; The temperature data is calculated by adding the temperature change to the preset initial temperature.

4. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The method for obtaining the temperature compensation value is as follows: Obtain the ambient temperature when the power cable elbow plug is in operation; Combining the wavelength change value and temperature data, the corrected measured temperature, that is, the temperature compensation value, is calculated.

5. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The method for obtaining the temperature warning value is as follows: Obtain the rated upper temperature limit of the plug, and calculate the difference between the rated upper temperature limit and the temperature data as a safety margin; The sum of the temperature compensation value and the safety margin is taken as the temperature warning value.

6. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The specific steps of comparing and analyzing the temperature data with the temperature warning value and issuing warning prompts and maintenance work in time according to the comparison and analysis results are as follows: When the temperature data obtained in real time is lower than the temperature warning value, there is no need to issue a warning and continuous monitoring is performed; When the temperature data obtained in real time is higher than the temperature warning value, an early warning will be issued in time and maintenance will be carried out.

7. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The specific calculation formula of the wavelength change value is as follows: In the formula, is the wavelength change value, is the initial wavelength, is the heating wavelength, is the thermal expansion coefficient of the optical fiber, is the thermo-optical coefficient, It's a time cycle.

8. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The specific calculation formula of the temperature data is as follows: In the formula, is the temperature data, is the initial temperature, It is the heat generated by the elbow plug. is the quality of the elbow plug, is the specific heat capacity of the elbow plug.

9. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The specific calculation formula of the temperature compensation value is as follows: In the formula, is the temperature compensation value, is the temperature data, is the ambient temperature, is the known rate of temperature rise, is the wavelength change value.

10. The method for intelligent online temperature early warning of a power cable elbow plug according to claim 1, characterized in that: The specific calculation formula of the temperature warning value is as follows: In the formula, is the temperature warning value, is the temperature compensation value, is the safety margin; The specific calculation formula of the safety margin is as follows: In the formula, is the safety margin, is the upper temperature rating, It is the temperature data.

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