A live monitoring system and device for detecting the health status of cables in operation

Abstract

The present invention belongs to the technical field of cable health status assessment, and in particular, relates to a live monitoring system and device for detecting the health status of cables in operation. The system includes a potential difference determination module, a live detection module, a leakage current acquisition module, an insulation voltage acquisition module, a health assessment module, and a score output alarm module; the device includes a single-phase switch, a current transformer, a high-precision voltage transmitter, a processor, and a memory. The present invention can dynamically adjust the maintenance frequency and depth according to the score, realize lean management, provide a more flexible early warning mechanism, make cable maintenance more targeted and flexible, and thus greatly reduce the number of unnecessary maintenance times, effectively solving the problem of unnecessary maintenance occurring too frequently and resulting in waste of computing power in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable health status assessment, and in particular relates to a live monitoring system and device for detecting the health status of cables in operation. Background Art

[0002] As the complexity of modern power systems increases, the transmission and distribution of electricity has become more dependent on cables. Especially in the context of accelerated urbanization and continued growth in electricity demand, power systems are facing higher operating requirements. As the core part of power transmission, cables not only have to carry a large number of power transmission tasks, but also have to work stably in complex and harsh environments. Therefore, ensuring the health of cables has become a vital part of power system management.

[0003] At present, cable monitoring technology mainly includes the following two common methods: by simultaneously monitoring the operating status of the cable grounding system and the insulation structure of the cable body, a comprehensive assessment of the cable's multi-level health status can be achieved. By arranging measuring electrodes on the outside of the cable insulation layer, cable defects can be accurately located to monitor the insulation health of high-voltage AC cables in real time and detect potential defects or faults in a timely manner.

[0004] However, in the implementation of existing cable monitoring technology, a single threshold method or a direct repair method based on defect location is often used to achieve monitoring, which results in the problem of unnecessary maintenance occurring too frequently, leading to a waste of computing power. Summary of the invention

[0005] In view of the above deficiencies in the prior art, the purpose of the present invention is to provide a live monitoring system and device for detecting the health status of cables in operation, which can dynamically adjust the maintenance frequency and depth according to the score, thereby realizing lean management.

[0006] The present invention provides a live monitoring system for detecting the health status of an in-service cable, comprising: a potential difference determination module, a live detection module, a leakage current acquisition module, an insulation voltage acquisition module, a health assessment module and a scoring output alarm module;

[0007] Among them, the potential difference determination module is used to obtain the potential difference between the steel armor grounding lead of the 10kV cable terminal head and the cabinet, and judge whether to obtain the current value and voltage value of the grounding lead under the energized state according to the potential difference. If the potential difference is zero, the current value and voltage value will continue to be collected under the energized state through the energized detection module. If the potential difference is not zero, a warning will be directly issued;

[0008] A live detection module is used to start the leakage current collection module and the insulation voltage collection module based on the bypass operation when the potential difference is zero;

[0009] A leakage current acquisition module is used to collect leakage current signals and analyze leakage current indexes based on the leakage current signals. The leakage current index is used to evaluate the current insulation state of the cable.

[0010] The insulation voltage acquisition module is used to disconnect the ground lead and put it in the live mode, obtain the voltage signal of the cable terminal through the voltage acquisition technology, and analyze the insulation voltage index based on the collected voltage signal. The insulation voltage index is used to evaluate the insulation status of the cable voltage;

[0011] The health assessment module is used to obtain the leakage current index and the insulation voltage index, and analyze the health status index based on the leakage current index and the insulation voltage index. The health status index is used to evaluate the health status of the cables in operation;

[0012] The scoring output alarm module is used to output the score of the current cable according to the health status index and the scoring rules, and automatically issue an alarm according to the score.

[0013] Preferably, at the steel armor grounding lead of the 10kV cable terminal head, a half-lapped insulation coating method is used to isolate the grounding lead from the insulation of the cabinet, wherein the withstand voltage of the insulation coating is 1000V.

[0014] Preferably, the bypass operation includes connecting a single-phase switch with a current capacity of 32A in series in the grounding braid loop.

[0015] Preferably, the leakage current signal collection method includes: a parallel shunt mode and a series current transformer mode;

[0016] The parallel shunt mode refers to connecting in parallel with the grounding braid to collect current signals in a shunt manner;

[0017] The series current transformer mode refers to collecting signals through a series current transformer;

[0018] The acquisition accuracy of the parallel shunt mode and the series current transformer mode both reaches the μA level.

[0019] Preferably, the steps for obtaining the leakage current index are:

[0020] Obtain the current ambient humidity value of the cable, the current ambient temperature value of the cable, and the leakage current value at the current time t, and perform preprocessing, and standardize the preprocessed current ambient humidity value of the cable, the current ambient temperature value of the cable, and the leakage current value at the current time t;

[0021] Obtaining a preset safety current threshold from a database;

[0022] The objective weighting method is used to obtain the weight of the current ambient humidity value of the cable for the leakage current index, the weight of the current ambient temperature value of the cable for the leakage current index, and the weight of the ratio of the leakage current value at the current time t to the preset safety current threshold for the leakage current index;

[0023] The leakage current index is calculated by the leakage current index calculation formula:

[0024] ;

[0025] In the formula, XLI is the leakage current index, e is the natural constant, π is the circumference of the circle, and H is the current humidity value of the cable environment. is the weight of H for XLI, T is the current ambient temperature of the cable, is the weight of T for XLI, is the leakage current value at the current time t, is the preset safety current threshold, for and The ratio of is the weight of XLI.

[0026] Preferably, the specific steps for obtaining the insulation voltage index are:

[0027] Obtain the insulation resistance value of the cable, the leakage current value at the current time t, and the actual voltage signal value at the current time t, and perform preprocessing, and standardize the insulation resistance value of the cable, the leakage current value at the current time t, and the actual voltage signal value at the current time t after the preprocessing;

[0028] Obtain the preset standard voltage value from the database;

[0029] Obtain the weight of the insulation resistance value of the cable for the insulation voltage index, the weight of the leakage current value at the current time t for the insulation voltage index, and the weight of the ratio of the actual voltage signal value at the current time t to the preset standard voltage value for the insulation voltage index through an objective weighting method;

[0030] The insulation voltage index is obtained by the insulation voltage index calculation formula:

[0031] ;

[0032] In the formula, JYI is the insulation voltage index, e is the natural constant, and R is the insulation resistance value of the cable. is the weight of R for JYI, is the leakage current value at the current time t, for For the weight of JYI, is the actual voltage signal value at the current time t, is the preset standard voltage value, for and The ratio of is the weight of JYI.

[0033] Preferably, the steps for obtaining the health status index are:

[0034] Obtain the leakage current index and insulation voltage index at the same time t;

[0035] The weights of leakage current index and insulation voltage index for health status index are obtained through objective weighting method.

[0036] The health status index is obtained through the health status index calculation formula.

[0037] Preferably, the health status index calculation formula is:

[0038] ;

[0039] Where, JKI is the health index, π is the circumference of the circle, XLI is the leakage current index, JYI is the insulation voltage index, is the weight of XLI for JKI, is the weight of JYI to JKI.

[0040] Preferably, the outputting of the score of the current cable according to the scoring rules and automatically giving an alarm according to the score specifically refers to:

[0041] When the cable health index score is less than 50 points, an alarm is triggered and a power outage is recommended for maintenance of the cable.

[0042] When the cable health index score is greater than or equal to 50 and less than 80, conduct live partial discharge and infrared detection once a week;

[0043] When the health index score of the cable is greater than or equal to 80, it is output that the cable is in a relatively healthy state.

[0044] A live monitoring device for detecting the health status of an in-service cable, used to implement the above system, comprises:

[0045] Single-phase switch for series ground pigtail loop;

[0046] Current transformer, used to collect current signals in series with wiring braids;

[0047] High-precision voltage transmitter for collecting voltage signals in ground lead disconnect mode;

[0048] A processor and a memory, wherein computer program instructions are stored in the memory, and when the processor is configured to execute the computer program instructions, the single-phase switch, the current transformer and the high-precision voltage transmitter perform setting actions.

[0049] The present invention has the following beneficial effects:

[0050] The present invention can dynamically adjust the maintenance frequency and depth according to the score, realizes lean management, provides a more flexible early warning mechanism, makes cable maintenance more targeted and flexible, thereby greatly reducing the number of unnecessary maintenance times, and effectively solves the problem of unnecessary maintenance occurring too frequently and resulting in waste of computing power in the prior art.

[0051] The present invention obtains the voltage signal of the cable terminal head through the voltage acquisition technology, and combined with the calculated insulation voltage index, can provide a comprehensive evaluation of the cable insulation status, thereby improving the monitoring accuracy, and can also discover possible insulation problems of the cable in advance to ensure the safe operation of the power system.

[0052] The present invention uses two collection methods, namely the parallel shunt mode and the series current transformer mode. The leakage current collection module can provide high-precision data, and provide an effective evaluation of the insulation state of the cable through the leakage current index, thereby ensuring the stable and safe operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the modules of the system of the present invention. DETAILED DESCRIPTION

[0054] The above technical solution is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0055] Example 1: Figure 1 As shown, a live monitoring system for detecting the health status of an in-service cable includes: a potential difference determination module, a live detection module, a leakage current acquisition module, an insulation voltage acquisition module, a health assessment module and a scoring output alarm module.

[0056] Among them, the potential difference determination module is used to obtain the potential difference between the steel armor grounding lead of the 10kV cable terminal head and the cabinet, and judge whether to obtain the current value and voltage value of the grounding lead under the energized state according to the potential difference. If the potential difference is zero, the current value and voltage value will continue to be collected under the energized state through the energized detection module. If the potential difference is not zero, a warning will be issued directly. At the steel armor grounding lead of the 10kV cable terminal head, a half-lapped insulation coating method is used to isolate the insulation of the grounding lead from the cabinet, and the insulation coating has a withstand voltage of 1000V.

[0057] In the live state, if the potential difference is zero, it means that the potential between the ground lead and the cabinet is equal. At this time, the system continues to work and collects current and voltage signals through the live detection module; if the potential difference is not zero, a warning is immediately issued, indicating that there may be a grounding problem or system failure. By collecting current and voltage data in the live state, the operating status and insulation performance of the cable can be accurately monitored to ensure that the cable will not be damaged or abnormal under normal working conditions. The ground lead is insulated using half-lapped insulation coating technology, which improves the insulation safety and pressure resistance of the ground lead, especially in high-voltage systems, avoiding electrical leakage or breakdown caused by excessive voltage, which not only improves the safety of the system, but also increases the operating stability of the system and the life of electrical equipment.

[0058] Among them, the insulation coating method is to cover the surface of the conductive material with insulating material in order to isolate the current and prevent current leakage or electrical failure. Withstand voltage refers to the maximum voltage that a material or component can withstand without breakdown or damage. The withstand voltage of the insulation coating material is 1000V, which means that the insulation layer can withstand a voltage of up to 1000V and ensure electrical isolation safety.

[0059] The live detection module is used to start the leakage current acquisition module and the insulation voltage acquisition module based on the bypass operation when the potential difference is zero, so as to monitor the insulation performance and current leakage of the cable system in real time. The bypass operation includes connecting a single-phase switch with a current capacity of 32A in series in the grounding braid loop.

[0060] Bypass operation is an operation mode that does not interfere with the normal power supply. It usually allows detection, monitoring or maintenance without power outage by installing additional switches or loops. Through the bypass operation mode, live monitoring can be carried out without cutting off the current supply of the cable, avoiding affecting the normal operation of the cable. By connecting a single-phase switch with a current capacity of 32A in series in the grounding pigtail loop, the bypass operation allows the safe collection of current and voltage signals when the power system is operating normally. This method does not affect the flow of electricity and can ensure the continuity of the power system.

[0061] By bypassing, effective live monitoring can be performed without power outages, minimizing the downtime of the power system and ensuring the continuity of power supply. The bypass switch can also be flexibly controlled, easy and safe to operate, avoiding safety hazards caused by power outages. Through the live detection module and the potential difference determination module, high-precision and real-time evaluation of insulation performance is ensured under live conditions, thereby generating a comprehensive health index and a graded alarm mechanism to provide complete monitoring and management of the cable's health status.

[0062] The 32A single-phase switch is an electrical switch with a current carrying capacity of 32 amperes. It is used to control the direction of current flow and is suitable for single-phase circuits. In addition, the 32A single-phase switch has a high current carrying capacity and can support high-load currents. By controlling the current flow direction, the accuracy and stability of current collection can be ensured. At the same time, it can ensure the high safety of the switch itself and avoid overload, short circuit or other faults under energized conditions.

[0063] The ground pigtail loop is a current path connecting the cable terminal, the ground lead and the grounding system. In the power system, the ground pigtail loop is used to ensure that the fault current is smoothly introduced into the ground through the ground wire to ensure the safety of the equipment. The switch in the bypass operation is installed in this loop to control the flow of current and monitor it.

[0064] The leakage current acquisition module is used to collect leakage current signals and analyze the leakage current index based on the leakage current signals. The leakage current index is used to evaluate the current insulation state of the cable, help monitor whether the cable has leakage current anomalies, ensure the safe operation of the power system, and help to timely discover potential insulation failures or aging problems, reducing safety hazards of the power system. In addition, the monitoring method of this module is non-invasive and will not affect the normal operation of the power system.

[0065] The methods for collecting leakage current signals include: parallel shunt mode and series current transformer mode; the parallel shunt mode refers to connecting in parallel with the grounding braid to collect current signals in a shunt manner; the series current transformer mode refers to collecting signals through series current transformers; the collection accuracy of the parallel shunt mode and the series current transformer mode both reaches the μA level.

[0066] In the parallel shunt mode, the leakage current signal is collected by connecting the measuring device in parallel with the grounding braid and collecting the current signal by shunt. This mode can accurately measure the current leakage value without interrupting the current, ensuring that the collection of current signals will not interfere with the power system, and is especially suitable for monitoring high voltage or high current systems. At the same time, by collecting current signals by shunt, the current leakage amount can be obtained more accurately, providing more accurate data to evaluate the insulation health of the cable.

[0067] The series current transformer mode monitors the current by connecting a current transformer in series in the cable loop. The series current transformer mode measures the leakage current signal by connecting a current transformer in series in the cable loop. A current transformer is a device used for current measurement that converts high current into low current or voltage for the measurement device to read. The current transformer can accurately capture the leakage current through the cable, especially in high voltage systems, showing excellent accuracy and stability. It can directly measure the leakage current through the cable. In this mode, the current transformer can effectively distinguish the tiny leakage current of the cable and has extremely high measurement accuracy.

[0068] μA-level accuracy means that the current acquisition device can measure current at the microampere level with an accuracy of 1μA (one millionth of an ampere). μA-level acquisition accuracy ensures accurate measurement of leakage current, allowing the detection system to capture even tiny changes in leakage current. In this way, the system can detect potential cable damage or insulation problems as early as possible, providing key data for later maintenance and repair, and preventing major power failures.

[0069] The steps for obtaining the leakage current index are as follows: obtain the current ambient humidity value of the cable, the current ambient temperature value of the cable, and the leakage current value at the current time t, and perform preprocessing, and standardize the preprocessed current ambient humidity value of the cable, the current ambient temperature value of the cable, and the leakage current value at the current time t to remove the data unit dimension; obtain the preset safety current threshold from the database; obtain the weight of the current ambient humidity value of the cable for the leakage current index, the weight of the current ambient temperature value of the cable for the leakage current index, and the weight of the ratio of the leakage current value at the current time t to the preset safety current threshold for the leakage current index through the objective weighting method; and obtain the leakage current index through the leakage current index calculation formula:

[0070] ;

[0071] In the formula, XLI is the leakage current index, e is the natural constant, π is the circumference of the circle, and H is the current humidity value of the cable environment. is the weight of H for XLI, T is the current ambient temperature of the cable, is the weight of T for XLI, is the leakage current value at the current time t, is the preset safety current threshold, for and The ratio of is the weight of XLI.

[0072] A specific example is as follows: the current humidity value of the cable environment is H=0.8, =0.3, the current ambient temperature of the cable is T=30 degrees Celsius, =0.3, leakage current value at current time t =40mA / km, preset safety current threshold =63mA / km, =0.4, and XLI=0.619 is calculated. The higher the leakage current index, the more current is leaking and the worse the health of the cable.

[0073] Among them, the current humidity value of the cable's environment can be measured by a capacitive humidity sensor through a change in capacitance. A humidity sensor is usually composed of a capacitor with a humidity-sensitive dielectric layer sandwiched between two electrodes of the capacitor. When water molecules in the air attach to the humidity-sensitive material, the dielectric constant of the dielectric changes, causing the capacitance value to change. After the sensor measures the capacitance change, it converts it into a humidity reading through a circuit. The current humidity value of the cable's environment can also be measured by a resistive humidity sensor using the resistance change of the humidity-sensitive material. When water vapor in the air is absorbed by the humidity-sensitive material, the resistance of the material changes. Changes in humidity directly affect changes in the sensor's resistance value, and by measuring the resistance change, the relative humidity of the air can be calculated.

[0074] The current ambient temperature of the cable can be measured by a resistance thermometer (such as a platinum resistor PT100) through the property that metal resistance changes with temperature. When measuring temperature, as the temperature rises, the resistance of the metal (such as platinum) increases, and the resistance change can be converted into a temperature value by measuring the circuit. The temperature can also be measured by a thermocouple using the thermoelectric potential difference generated by different metal materials when the temperature changes. Thermocouples are composed of two different metal materials. When the temperature changes, the potential difference between the two materials also changes. The temperature value is obtained by measuring the potential difference.

[0075] By combining multi-dimensional parameters, the leakage current index not only reflects the insulation status of the cable itself, but also comprehensively considers the impact of external environmental factors such as temperature and humidity on the health status of the cable. Especially in the case of large environmental changes, it can provide monitoring personnel with more accurate cable health data.

[0076] The insulation voltage acquisition module is used to disconnect the ground lead and put it in the energized mode, obtain the voltage signal of the cable terminal through the voltage acquisition technology, and analyze the insulation voltage index based on the collected voltage signal. The insulation voltage index is used to evaluate the cable voltage insulation status.

[0077] Through high-precision voltage signal acquisition, the voltage insulation performance of the cable can be accurately reflected. When collecting voltage signals, the interference caused by the ground lead or other electrical factors can be eliminated, so that the measured voltage value is closer to the actual insulation status of the cable. This helps to detect insulation problems early, such as aging, cracks or damage to the outer insulation layer of the cable, thereby reducing the safety hazards of power equipment caused by cable failures. The voltage acquisition module provides dynamic real-time data, which can help power system managers understand the voltage insulation status of the cable at any time.

[0078] This real-time monitoring avoids regular manual inspection and sampling of cables, improves monitoring efficiency, and ensures that the cable insulation performance is always within a safe range. Ground lead disconnection refers to cutting off the electrical connection between the cable and the grounding system during cable health monitoring to ensure that the test equipment can obtain accurate voltage signals without ground interference. It is usually performed in live mode to avoid ground loops affecting the test results.

[0079] The specific steps for obtaining the insulation voltage index are as follows: obtain the insulation resistance value of the cable, the leakage current value at the current time t, and the actual voltage signal value at the current time t, and perform preprocessing to standardize the insulation resistance value of the cable, the leakage current value at the current time t, and the actual voltage signal value at the current time t after preprocessing; obtain the preset standard voltage value from the database; obtain the weight of the insulation resistance value of the cable for the insulation voltage index, the weight of the leakage current value at the current time t for the insulation voltage index, and the weight of the ratio of the actual voltage signal value at the current time t to the preset standard voltage value for the insulation voltage index through the objective weighting method; and obtain the insulation voltage index through the insulation voltage index calculation formula:

[0080] ;

[0081] In the formula, JYI is the insulation voltage index, R is the insulation resistance value of the cable, is the weight of R for JYI, is the leakage current value at the current time t, for For the weight of JYI, is the actual voltage signal value at the current time t, is the preset standard voltage value, for and The ratio of is the weight of JYI.

[0082] A specific example is as follows: the insulation resistance value of the cable is R=50 ohms, =0.35, leakage current value at current time t =45mA / km, =0.35, the actual voltage signal value at the current time t =9.8kV, the preset standard voltage value =10kV, =0.3, calculated JYI=0.710. The higher the insulation voltage index, the better the voltage insulation effect and the better the health of the cable in operation.

[0083] The insulation resistance value of the cable can be obtained through a high-voltage megohmmeter. The actual voltage signal value at the current time t is obtained through high-precision voltage acquisition technology, where the high-precision voltage acquisition technology refers to the actual voltage signal at the current time t being collected through a high-precision voltage transmitter in the disconnected mode of the ground lead; the voltage signal acquisition accuracy reaches the uV level.

[0084] The health assessment module is used to obtain the leakage current index and the insulation voltage index, and analyze the health status index based on the leakage current index and the insulation voltage index. The health status index is used to evaluate the health status of the cable in operation.

[0085] The health assessment module provides real-time and accurate assessment of the cable health status by comprehensively analyzing the leakage current index and insulation voltage index. It can not only predict cable failures in advance, but also optimize operation and maintenance strategies, reduce unnecessary maintenance and inspection work, thereby reducing operation and maintenance costs and improving the stability and reliability of the power system.

[0086] The steps to obtain the health status index are: obtain the leakage current index and insulation voltage index at the same time t; obtain the weights of the leakage current index and insulation voltage index for the health status index through the objective weighting method; and obtain the health status index through the health status index calculation formula. The health status index calculation formula is:

[0087] ;

[0088] Where, JKI is the health index, π is the circumference of the circle, XLI is the leakage current index, JYI is the insulation voltage index, is the weight of XLI for JKI, is the weight of JYI to JKI.

[0089] A specific example is as follows: XLI = 0.619, =0.5, =0.5, JYI=0.710, and JKI=0.688. The higher the health index, the better the health of the cable in operation, and vice versa.

[0090] The scoring output alarm module is used to output the score of the current cable according to the health status index and the scoring rules, and automatically issue an alarm according to the score.

[0091] The score of the current cable is output according to the scoring rules, and an alarm is automatically issued based on the score. Specifically, when the cable health index score is less than 50 points, an alarm is triggered, and a power outage is recommended for maintenance of the cable. When the cable health index score is greater than or equal to 50 and less than 80, live partial discharge and infrared detection are carried out once a week. When the cable health index score is greater than or equal to 80, the cable is output to be in a relatively healthy state.

[0092] The scoring output alarm module clearly distinguishes different levels of health status through the automatically generated health status index. According to the score, the maintenance frequency and depth are dynamically adjusted, which realizes lean management and provides a more flexible early warning mechanism, making cable maintenance more targeted and flexible, and greatly reducing the number of unnecessary maintenance.

[0093] Embodiment 2: A live monitoring device for detecting the health status of an in-service cable, used to implement the system in Embodiment 1, comprising:

[0094] Single-phase switch for series ground pigtail loop;

[0095] Current transformer, used to collect current signals in series with wiring braids;

[0096] High-precision voltage transmitter for collecting voltage signals in ground lead disconnect mode;

[0097] A processor and a memory, wherein computer program instructions are stored in the memory, and when the processor is configured to execute the computer program instructions, the single-phase switch, the current transformer and the high-precision voltage transmitter perform setting actions.

Claims

1. A live monitoring system for detecting the health status of an in-service cable, characterized in that: include: Potential difference determination module, live detection module, leakage current acquisition module, insulation voltage acquisition module, health assessment module and scoring output alarm module; Among them, the potential difference determination module is used to obtain the potential difference between the steel armor grounding lead of the 10kV cable terminal head and the cabinet, and judge whether to obtain the current value and voltage value of the grounding lead under the energized state according to the potential difference. If the potential difference is zero, the current value and voltage value will continue to be collected under the energized state through the energized detection module. If the potential difference is not zero, a warning will be directly issued; A live detection module is used to start the leakage current collection module and the insulation voltage collection module based on the bypass operation when the potential difference is zero; A leakage current acquisition module is used to collect leakage current signals and analyze leakage current indexes based on the leakage current signals. The leakage current index is used to evaluate the current insulation state of the cable. The insulation voltage acquisition module is used to disconnect the ground lead and put it in the live mode, obtain the voltage signal of the cable terminal through the voltage acquisition technology, and analyze the insulation voltage index based on the collected voltage signal. The insulation voltage index is used to evaluate the insulation status of the cable voltage; The health assessment module is used to obtain the leakage current index and the insulation voltage index, and analyze the health status index based on the leakage current index and the insulation voltage index. The health status index is used to evaluate the health status of the cables in operation; The scoring output alarm module is used to output the score of the current cable according to the health status index and the scoring rules, and automatically issue an alarm according to the score; The steps for obtaining the leakage current index are: Obtain the current ambient humidity value of the cable, the current ambient temperature value of the cable, and the leakage current value at the current time t, and perform preprocessing, and standardize the preprocessed current ambient humidity value of the cable, the current ambient temperature value of the cable, and the leakage current value at the current time t; Obtaining a preset safety current threshold from a database; The objective weighting method is used to obtain the weight of the current ambient humidity value of the cable for the leakage current index, the weight of the current ambient temperature value of the cable for the leakage current index, and the weight of the ratio of the leakage current value at the current time t to the preset safety current threshold for the leakage current index; The leakage current index is calculated by the leakage current index calculation formula: ； In the formula, XLI is the leakage current index, e is the natural constant, π is the circumference of the circle, and H is the current humidity value of the cable environment. is the weight of H for XLI, T is the current ambient temperature of the cable, is the weight of T for XLI, is the leakage current value at the current time t, is the preset safety current threshold, for and The ratio of is the weight of XLI; The specific steps for obtaining the insulation voltage index are as follows: Obtain the insulation resistance value of the cable, the leakage current value at the current time t, and the actual voltage signal value at the current time t, and perform preprocessing, and standardize the insulation resistance value of the cable, the leakage current value at the current time t, and the actual voltage signal value at the current time t after the preprocessing; Obtain the preset standard voltage value from the database; Obtain the weight of the insulation resistance value of the cable for the insulation voltage index, the weight of the leakage current value at the current time t for the insulation voltage index, and the weight of the ratio of the actual voltage signal value at the current time t to the preset standard voltage value for the insulation voltage index through an objective weighting method; The insulation voltage index is obtained by the insulation voltage index calculation formula: ； In the formula, JYI is the insulation voltage index, e is the natural constant, and R is the insulation resistance value of the cable. is the weight of R for JYI, is the leakage current value at the current time t, for For the weight of JYI, is the actual voltage signal value at the current time t, is the preset standard voltage value, for and The ratio of is the weight of JYI.

2. A live monitoring system for detecting the health status of an in-service cable according to claim 1, characterized in that: At the steel armor grounding lead of the 10kV cable terminal head, a half-lapped insulation coating method is used to isolate the grounding lead from the insulation of the cabinet, wherein the withstand voltage of the insulation coating is 1000V.

3. A live monitoring system for detecting the health status of an in-service cable according to claim 1, characterized in that: The bypass operation includes connecting a single-phase switch with a current capacity of 32A in series in the grounding pigtail loop.

4. A live monitoring system for detecting the health status of an in-service cable according to claim 3, characterized in that: The leakage current signal collection method includes: parallel shunt mode and series current transformer mode; The parallel shunt mode refers to connecting in parallel with the grounding braid to collect current signals in a shunt manner; The series current transformer mode refers to collecting signals through a series current transformer; The acquisition accuracy of the parallel shunt mode and the series current transformer mode both reaches the μA level.

5. The live monitoring system for detecting the health status of an in-service cable according to claim 1, characterized in that: The steps for obtaining the health status index are as follows: Obtain the leakage current index and insulation voltage index at the same time t; The weights of leakage current index and insulation voltage index for health status index are obtained through objective weighting method. The health status index is obtained through the health status index calculation formula.

6. A live monitoring system for detecting the health status of an in-service cable according to claim 5, characterized in that: The health status index calculation formula is: ； Where, JKI is the health index, π is the circumference of the circle, XLI is the leakage current index, JYI is the insulation voltage index, is the weight of XLI for JKI, is the weight of JYI to JKI.

7. A live monitoring system for detecting the health status of an in-service cable according to claim 1, characterized in that: Outputting the score of the current cable according to the scoring rules and automatically giving an alarm according to the score specifically refers to: When the cable health index score is less than 50 points, an alarm is triggered and a power outage is recommended for maintenance of the cable. When the cable health index score is greater than or equal to 50 and less than 80, conduct live partial discharge and infrared detection once a week; When the health index score of the cable is greater than or equal to 80, it is output that the cable is in a relatively healthy state.

8. A live monitoring device for detecting the health status of an in-service cable, used to implement the system according to any one of claims 1 to 7, characterized in that: include: Single-phase switch for series ground pigtail loop; Current transformer, used to collect current signals in series with wiring braids; High-precision voltage transmitter for collecting voltage signals in ground lead disconnect mode; A processor and a memory, wherein computer program instructions are stored in the memory, and when the processor is configured to execute the computer program instructions, the single-phase switch, the current transformer and the high-precision voltage transmitter perform setting actions.

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