Cable insulation state detection method, device and equipment

Abstract

The invention relates to a cable insulation state detection method, device and equipment. The method comprises the following steps: acquiring a first electrical parameter, a second electrical parameter and temperature and humidity data of a to-be-detected cable; determining the branch relaxation time of the cable to be detected and the ratio of depolarization current to polarization current according to the first electrical parameter; correcting the second electrical parameter according to the temperature and humidity data to obtain a corrected second electrical parameter; determining the dielectric loss frequency asymmetry degree, the high-frequency polarization loss slope and the quality factor peak offset of the to-be-detected cable according to the corrected second electrical parameter; and determining an insulation state detection result of the to-be-detected cable according to the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry degree, the high-frequency polarization loss slope and the quality factor peak offset. By adopting the method, the real-time monitoring of the insulation state of the cable can be realized.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a method, device and equipment for detecting the insulation status of a cable. Background Art

[0002] In modern power systems, cross-linked polyethylene (XLPE) cables, thanks to their superior electrical performance, excellent mechanical properties, and high reliability, have become a core carrier for power transmission. However, as XLPE cables age over time, they are exposed to complex environmental factors such as high electric field strength, temperature fluctuations, moisture corrosion, and mechanical stress. This deteriorates their insulation performance, and insulation aging is becoming an increasingly prominent issue.

[0003] In the related art, cable insulation detection methods are mainly implemented through manual inspection. However, manual inspection is inefficient and has a long detection cycle, which makes it difficult to meet the power system's demand for real-time monitoring of cable insulation status. Summary of the Invention

[0004] Based on this, it is necessary to provide a cable insulation status detection method, device and equipment that can realize real-time monitoring of the cable insulation status in order to solve the above technical problems.

[0005] In a first aspect, the present application provides a method for detecting the insulation status of a cable, comprising:

[0006] Acquire a first electrical parameter, a second electrical parameter, and temperature and humidity data of the cable to be detected, wherein the first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected;

[0007] Determining, based on the first electrical parameter, a branch relaxation time and a ratio of a depolarization current to a polarization current of the cable to be detected;

[0008] Correcting the second electrical parameter according to the temperature and humidity data to obtain a corrected second electrical parameter;

[0009] Determining the dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak shift of the cable to be tested based on the corrected second electrical parameter;

[0010] The insulation state detection result of the cable to be detected is determined according to the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset.

[0011] In one embodiment, determining the branch relaxation time and the ratio of the depolarization current to the polarization current of the cable to be detected based on the first electrical parameter includes:

[0012] Inputting the first electrical parameter into a parallel equivalent circuit model to determine the equivalent resistance and capacitance of the cable to be tested;

[0013] Determining the branch relaxation time according to the equivalent resistance value and the capacitance value;

[0014] Extracting the depolarization current value and the polarization current value of the cable to be tested from the first electrical parameter;

[0015] The ratio of the depolarization current to the polarization current is obtained according to the extracted depolarization current value and polarization current value.

[0016] In one embodiment, before determining the branch relaxation time and the ratio of the depolarization current to the polarization current of the cable to be tested based on the first electrical parameter, the method further includes:

[0017] The first electrical parameter is filtered to remove noise interference in the first electrical parameter.

[0018] In one embodiment, the correcting the second electrical parameter according to the temperature and humidity data to obtain the corrected second electrical parameter includes:

[0019] Determining the corrected temperature of the environment where the cable to be tested is located based on the temperature and humidity data;

[0020] The second electrical parameter is temperature compensated according to the correction temperature to obtain the corrected second electrical parameter.

[0021] In one embodiment, determining the dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak shift of the cable to be tested based on the corrected second electrical parameter includes:

[0022] Determining the frequency domain integral of the corrected second electrical parameter, and determining the dielectric loss frequency asymmetry based on the frequency domain integral of the corrected second electrical parameter;

[0023] Performing logarithmic difference on the corrected second electrical parameter to obtain a dielectric constant imaginary part frequency curve, and performing least squares linear fitting on the dielectric constant imaginary part frequency curve to obtain the high-frequency polarization loss slope;

[0024] The quality factor corresponding to the cable to be detected is determined according to the corrected second electrical parameter, and a quality factor peak offset corresponding to the quality factor is determined.

[0025] In one embodiment, determining the insulation status test result of the cable to be tested based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift includes:

[0026] Generate a characteristic matrix of the insulation state of the cable to be tested according to the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift;

[0027] Generate a thermal aging index and an electrical tree aging index of the cable to be tested using a characteristic matrix of the insulation state of the cable to be tested;

[0028] The insulation state detection result of the cable to be detected is determined according to the thermal aging index and the electrical tree aging index.

[0029] In one embodiment, determining the insulation status test result of the cable to be tested based on the thermal aging index and the electrical tree aging index includes:

[0030] Comparing the thermal aging index with a thermal aging threshold to obtain a first comparison result;

[0031] comparing the electrical tree aging index with an electrical tree aging threshold to obtain a second comparison result;

[0032] The insulation state detection result is determined according to the first comparison result and the second comparison result.

[0033] In one embodiment, determining the insulation status test result of the cable to be tested based on the thermal aging index and the electrical tree aging index includes:

[0034] Calculating a health parameter of the cable to be tested according to the thermal aging index and the electrical tree aging index;

[0035] An insulation status detection result of the cable to be detected is determined according to the health parameter.

[0036] In a second aspect, the present application provides a device for detecting the insulation status of a cable, comprising:

[0037] an acquisition module, configured to acquire a first electrical parameter, a second electrical parameter, and temperature and humidity data of the cable to be detected, wherein the first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected;

[0038] a feature determination module, configured to determine, based on the first electrical parameter, a branch relaxation time and a ratio of a depolarization current to a polarization current of the cable to be detected; correct the second electrical parameter based on the temperature and humidity data to obtain a corrected second electrical parameter; and determine, based on the corrected second electrical parameter, a dielectric loss frequency asymmetry, a high-frequency polarization loss slope, and a quality factor peak offset of the cable to be detected;

[0039] The detection module is used to determine the insulation status detection result of the cable to be detected based on the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset.

[0040] In one embodiment, the feature determination module is further used to input the first electrical parameter into a parallel equivalent circuit model to determine the equivalent resistance value and capacitance value of the cable to be detected; determine the branch relaxation time based on the equivalent resistance value and the capacitance value; extract the depolarization current value and polarization current value of the cable to be detected from the first electrical parameter; and obtain the ratio of the depolarization current to the polarization current based on the extracted depolarization current value and polarization current value.

[0041] In one embodiment, the acquisition module is further configured to filter the first electrical parameter to remove noise interference in the first electrical parameter.

[0042] In one embodiment, the feature determination module is further used to determine the correction temperature of the environment where the cable to be detected is located based on the temperature and humidity data; and perform temperature compensation on the second electrical parameter based on the correction temperature to obtain the corrected second electrical parameter.

[0043] In one embodiment, the feature determination module is further used to determine the frequency domain integral of the corrected second electrical parameter, and determine the dielectric loss frequency asymmetry based on the frequency domain integral of the corrected second electrical parameter; perform logarithmic difference on the corrected second electrical parameter to obtain the dielectric constant imaginary part frequency curve, and perform least squares linear fitting on the dielectric constant imaginary part frequency curve to obtain the high-frequency polarization loss slope; determine the quality factor corresponding to the cable to be tested based on the corrected second electrical parameter, and determine the quality factor peak offset corresponding to the quality factor.

[0044] In one embodiment, the detection module is further used to generate a characteristic matrix of the insulation state of the cable to be detected based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset; use the characteristic matrix of the insulation state of the cable to be detected to generate a thermal aging index and an electrical tree aging index of the cable to be detected; and determine the insulation state detection result of the cable to be detected based on the thermal aging index and the electrical tree aging index.

[0045] In one embodiment, the detection module is further used to compare the thermal aging index with the thermal aging threshold to obtain a first comparison result; compare the electrical tree aging index with the electrical tree aging threshold to obtain a second comparison result; and determine the insulation state detection result based on the first comparison result and the second comparison result.

[0046] In one embodiment, the detection module is configured to calculate a health parameter of the cable to be detected based on the thermal aging index and the electrical tree aging index; and determine an insulation status detection result of the cable to be detected based on the health parameter.

[0047] In a third aspect, the present application further provides a cable insulation status detection system, the cable insulation status detection system comprising: a main controller, an auxiliary controller, a timer, a high-voltage switch, a DC voltage source, an AC voltage source, an electrical parameter detection device, and a temperature and humidity sensor;

[0048] The main controller is connected to the temperature and humidity sensor, the electrical parameter detection device, the high-voltage switch and the auxiliary controller respectively; the high-voltage switch is connected to the DC voltage source and the AC voltage source; the auxiliary controller is connected to the timer;

[0049] The main controller is configured to execute the method for detecting the insulation status of the cable according to the first aspect;

[0050] The high-voltage switch is used to switch between the DC voltage source or the AC voltage source to form a DC voltage source detection loop or an AC voltage source detection loop on the cable to be tested;

[0051] The electrical parameter detection device is used to detect a first electrical parameter when forming a DC voltage source detection loop, and to detect a second electrical parameter when forming an AC voltage source detection loop;

[0052] The temperature and humidity sensor is used to detect the temperature and humidity of the environment where the cable to be tested is located;

[0053] The auxiliary controller is used to cooperate with the timer to control the working sequence of each device in the cable insulation status detection system.

[0054] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for detecting the insulation status of a cable as described in the first aspect above.

[0055] In a fifth aspect, the present application further provides a computer program product, comprising a computer program, which, when executed by a processor, implements the method for detecting the insulation status of a cable as described in the first aspect above.

[0056] The above-mentioned cable insulation status detection method, device and equipment obtain the first electrical parameter, second electrical parameter and temperature and humidity data of the cable to be detected, where the first electrical parameter is the DC polarization and depolarization electrical parameter corresponding to the DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is the AC high-frequency dielectric spectrum parameter corresponding to the AC voltage source detection circuit of the cable to be detected; based on the first electrical parameter, the branch relaxation time of the cable to be detected and the ratio of depolarization current to polarization current are determined; based on the temperature and humidity data, the second electrical parameter is corrected to obtain the corrected second electrical parameter; based on the corrected second electrical parameter, the dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset of the cable to be detected are determined; based on the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset, the insulation status detection result of the cable to be detected is determined. By obtaining the DC polarization and depolarization electrical parameters corresponding to the DC voltage source detection circuit and the AC high-frequency dielectric spectrum parameters corresponding to the AC voltage source detection circuit, the branch relaxation time, the ratio of depolarization current to polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset, which are characteristics related to the insulation state, are determined. Based on these characteristics related to the insulation state, the insulation state detection result of the cable to be tested is determined, thereby eliminating the need for manual inspection and enabling real-time data collection and calculation, thereby realizing real-time monitoring of the cable insulation state. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 A schematic diagram of a cable insulation status detection system provided in an embodiment of the present application;

[0059] Figure 2 A schematic flow chart of a method for detecting the insulation status of a cable provided in an embodiment of the present application;

[0060] Figure 3 A schematic structural diagram of an XLPE cable provided in an embodiment of the present application;

[0061] Figure 4 A schematic diagram of feature fusion provided in an embodiment of the present application;

[0062] Figure 5 A schematic flow chart of another method for detecting the insulation status of a cable provided in an embodiment of the present application;

[0063] Figure 6 A schematic flow chart of another method for detecting the insulation status of a cable provided in an embodiment of the present application;

[0064] Figure 7 A structural block diagram of a device for detecting the insulation status of a cable provided in an embodiment of the present application;

[0065] Figure 8 This is a diagram of the internal structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0067] First, the related technology will be described below.

[0068] In modern power systems, cross-linked polyethylene (XLPE) cables, thanks to their superior electrical performance, excellent mechanical properties, and high reliability, have become a core carrier for power transmission. XLPE cables are widely used because they effectively isolate electric fields under normal operating conditions, possess excellent resistance to electrical breakdown, and are adaptable to diverse installation environments. XLPE cables account for over 85% of medium- and low-voltage distribution networks in urban power grids, and they also occupy a significant share of high-voltage transmission lines of 110 kV and above.

[0069] As XLPE cables continue to operate for extended periods, they are exposed to complex environmental factors such as high electric field strength, temperature fluctuations, moisture intrusion, and mechanical stress. This gradually degrades their insulation performance, and insulation aging becomes increasingly prominent. Insulation aging causes microstructural changes in the cable insulation layer, further reducing the insulation resistance and increasing leakage current. This not only increases power loss but can also cause localized overheating. Increased dielectric loss leads to increased heating of the insulation material, creating a vicious cycle. The occurrence of partial discharge signals further exacerbation of insulation defects. Once cable insulation breakdown occurs, widespread power outages can result, causing significant losses to socioeconomic development and public well-being.

[0070] In the related art, the cable insulation detection method is mainly implemented through manual inspection. However, manual inspection is inefficient and has a long detection cycle, which makes it difficult to meet the power system's demand for real-time monitoring of the insulation status of cables. In addition, the cable insulation detection method in the related art cannot continuously monitor the cable insulation and it is difficult to capture the dynamic process of the gradual deterioration of insulation performance. With the continuous growth of electricity demand and the in-depth promotion of smart grid construction, higher requirements are placed on the efficiency, accuracy and real-time performance of cable insulation detection. Therefore, the development of a detection method that can automatically, accurately and in real time monitor the insulation status of cables has become a key issue that needs to be urgently addressed in the current power industry.

[0071] To solve the above problems, the embodiments of the present application provide a method, device and equipment for detecting the insulation status of a cable, which obtains the DC polarization and depolarization electrical parameters corresponding to the DC voltage source detection circuit and the AC high-frequency dielectric spectrum parameters corresponding to the AC voltage source detection circuit, thereby determining the branch relaxation time, the ratio of depolarization current to polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset, which are related to the insulation status. Based on these characteristics related to the insulation status, the insulation status detection result of the cable to be detected is determined, thereby eliminating the need for manual inspection and performing real-time data collection and calculation, thereby realizing real-time monitoring of the insulation status of the cable.

[0072] The method for detecting the insulation status of a cable provided in the embodiment of the present application can be applied to Figure 1 The cable insulation status detection system shown in the figure is used to detect the insulation status of the cable to be tested. The cable insulation status detection system includes: a main controller, an auxiliary controller, a timer, a high-voltage switch, a DC voltage source, an AC voltage source, an electrical parameter detection device, and a temperature and humidity sensor.

[0073] like Figure 1As shown, the main controller is connected to the temperature and humidity sensor, the electrical parameter detection device, the high-voltage switch and the auxiliary controller respectively; the high-voltage switch is connected to the DC voltage source and the AC voltage source; the auxiliary controller is connected to the timer.

[0074] The main controller is configured to execute the cable insulation status detection method provided in the embodiment of the present application. For example, the main controller can be a host computer responsible for data processing, monitoring and instruction sending in the cable insulation status detection system.

[0075] In some embodiments, the main controller can also initialize the cable insulation status detection system. For example, the main controller configures parameters for devices such as the high-voltage switch, auxiliary controller, timer, electrical parameter measurement device, and temperature and humidity sensor according to a preset detection scheme, and performs device self-tests to ensure that the hardware of each device is normal, the communication link is unobstructed, and the entire system is in an operational state.

[0076] The high-voltage switch is used to switch between a DC voltage source and an AC voltage source to form a DC voltage source detection loop or an AC voltage source detection loop on the cable under test. Accordingly, the DC voltage source can provide a DC detection voltage, and the AC voltage source can provide an AC detection voltage.

[0077] For example, the main controller can send an instruction to the high-voltage switch to instruct the high-voltage switch to switch between a DC voltage source or an AC voltage source. After receiving the instruction, the high-voltage switch connects the DC voltage source or the AC voltage source to the detection circuit according to the detection requirements indicated by the instruction.

[0078] The electrical parameter detection device is configured to detect a first electrical parameter when forming a DC voltage source detection loop, and detect a second electrical parameter when forming an AC voltage source detection loop, and transmit the first and second electrical parameters to the main controller.

[0079] Exemplarily, when a DC voltage source is connected to the detection circuit, the electrical parameter detection device measures the polarization and depolarization current data of the cable under test at different DC voltages as the first electrical parameter, which is used to subsequently calculate DC parameters such as polarization index and insulation resistance. When an AC voltage source is connected, the high-frequency dielectric spectrum data of the cable under test is measured in the frequency range of 1Hz-10kHz to determine parameters such as the dielectric constant and dielectric loss factor corresponding to different frequencies.

[0080] The temperature and humidity sensor is used to detect the temperature and humidity of the environment in which the cable under test is located. Furthermore, the temperature and humidity sensor can also transmit the temperature and humidity information of the environment in which the cable under test is located to the main controller, so that the impact of environmental factors on the cable insulation performance can be considered during data analysis.

[0081] Among them, the auxiliary controller is used to cooperate with the timer to control the working sequence of each device in the cable insulation status detection system.

[0082] Exemplarily, the auxiliary controller may be a programmable logic controller (PLC). Upon receiving instructions from the main controller, the PLC coordinates with devices in the cable insulation status detection system, such as a timer, to control the operating sequence of various devices according to a pre-set detection process.

[0083] In some embodiments, the PLC controller is also connected to the high-voltage circuit breaker. When the detection is completed or an abnormal situation occurs (such as overvoltage, overcurrent, insulation breakdown, etc.), the PLC controller quickly controls the high-voltage circuit breaker to cut off the detection circuit according to the instructions of the main controller or the preset fault judgment logic to ensure system safety.

[0084] In some embodiments, the cable insulation status detection system may also include a protective device and a leakage shielding ring to ensure the safety and accuracy of the detection process. The protective device prevents abnormal conditions such as overvoltage and overcurrent from causing damage to equipment and personnel; the leakage shielding ring reduces leakage current and external interference during the detection process, thereby improving the reliability of the detection data.

[0085] Illustratively, the protection device may include an overvoltage protection device and an overcurrent protection device. When the detected circuit voltage exceeds a preset safety threshold, the overvoltage protection device rapidly activates, limiting the voltage or disconnecting the circuit to prevent excessive voltage from damaging equipment and personnel. Illustratively, when the overcurrent protection module detects an abnormal increase in the circuit current, it promptly disconnects the circuit to prevent safety incidents such as equipment failure or fire caused by the overcurrent.

[0086] Exemplarily, the anti-leakage shielding ring may be made of metal and surround the insulation between the high-voltage and low-voltage ends of the tested cable, thereby effectively reducing the impact of leakage current during the test process and improving the reliability and stability of the test data.

[0087] In an exemplary embodiment, Figure 2 As shown, a method for detecting the insulation status of a cable is provided, and the method is applied to Figure 1 The main controller in the example is used to illustrate, including S201-S205:

[0088] S201: Acquire a first electrical parameter, a second electrical parameter, and temperature and humidity data of a cable to be detected.

[0089] The first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected.

[0090] It should be understood that the embodiments of the present application do not limit the cable to be detected, and it can be any type of insulated cable. In some embodiments, the cable to be detected can be an XLPE cable. For example, Figure 3 A schematic diagram of the structure of an XLPE cable provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, XLPE cables have a multi-layer, coiled structure, with the innermost core being the high voltage (HV) cable. From the inside out, the cables consist of a conductor shield, insulation layer, insulation shield, water-blocking buffer layer, and outer sheath. To eliminate the effects of creepage current during testing, the insulation shield, water-blocking buffer layer, and outer sheath can be stripped from the cable ends, exposing the insulation layer and leaving sufficient creepage distance (for example, 15 to 20 cm).

[0091] It should be understood that the embodiments of the present application do not limit how to obtain the first electrical parameter, the second electrical parameter, and the temperature and humidity data of the cable to be tested. In some embodiments, the first electrical parameter can be collected by the electrical parameter detection device when a DC voltage source detection loop is formed on the cable to be tested and then sent to the main controller. The first electrical parameter can be collected by the electrical parameter detection device when an AC voltage source detection loop is formed on the cable to be tested and then sent to the main controller. The temperature and humidity data can be sent to the main controller after the temperature and humidity of the environment in which the cable to be tested is located is detected by a temperature and humidity sensor.

[0092] In some embodiments, the main controller can send instructions to the high-voltage switch based on detection requirements to instruct the high-voltage switch to switch. After receiving the instructions, the high-voltage switch quickly and smoothly switches between the DC voltage source and the AC voltage source, connecting the adapted voltage source to the detection circuit. Subsequently, the electrical parameter detection device detects a first electrical parameter when forming a DC voltage source detection circuit, and detects a second electrical parameter when forming an AC voltage source detection circuit, and sends the first and second electrical parameters to the main controller.

[0093] It should be noted that during the process of the high-voltage switch realizing the switching operation between the DC voltage source and the AC voltage source, and the electrical parameter detection device detecting the first electrical parameter and the second electrical parameter, the auxiliary controller cooperates with the timer to strictly control the switching process and the detection process according to the preset timing, ensuring that the switching process and the detection process are safe and interference-free, and ensuring the accuracy of the detection data.

[0094] Exemplarily, the measurement of the first electrical parameter includes the measurement of the polarization process and the measurement of the depolarization process. Within the preset time-domain dielectric spectrum measurement time, the high-voltage switch connects the DC voltage source to the detection circuit to form a DC detection circuit. The timer controls the high-voltage circuit breaker power supply connection to be opened. The voltage and current signals of the polarization process of the cable under test are measured by the electrical parameter measurement device, and the polarization measurement data is sent to the main controller for storage and analysis. After the polarization process measurement is completed, the high-voltage circuit breaker power supply connection is disconnected, and the depolarization process of the cable under test sample is automatically short-circuited, and the depolarization measurement data is obtained, so that the depolarization measurement data and the polarization measurement data constitute the first electrical parameter.

[0095] Exemplarily, within the preset frequency domain dielectric spectrum measurement range, the high-voltage switch connects the AC voltage source to the detection circuit to form an AC detection circuit, the timer controls the high-voltage circuit breaker power supply connection to open, and the electrical parameter measuring device completes the measurement of the voltage and current signals of the cable under test to obtain the second electrical parameter, and sends the second electrical parameter to the main controller for storage and analysis.

[0096] In some embodiments, after collecting the first electrical parameter, second electrical parameter and temperature and humidity data of the cable to be tested, the main processor can also store and back up the above data in real time. The storage format adopts a general format that is convenient for data analysis and long-term preservation, and backs up to a local storage device to ensure the security and traceability of the data.

[0097] S202: Determine the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current according to the first electrical parameter.

[0098] In this step, after the main controller obtains the first electrical parameter, the second electrical parameter and the temperature and humidity data of the cable to be detected, the branch relaxation time and the ratio of the depolarization current to the polarization current of the cable to be detected can be determined according to the first electrical parameter.

[0099] The branch relaxation time is the characteristic time constant required for the material of the cable under test to polarize under the action of an external electric field, or to return to equilibrium after the electric field is removed, in the equivalent circuit. A shorter branch relaxation time indicates a faster polarization or depolarization process; a longer branch relaxation time indicates a slower polarization or depolarization process.

[0100] In some embodiments, the main controller inputs the first electrical parameter into a parallel equivalent circuit model to determine the equivalent resistance and capacitance values ​​of the cable to be tested, and determines the branch relaxation time based on the equivalent resistance and capacitance values. Furthermore, the main controller may extract the depolarization current and polarization current values ​​of the cable to be tested from the first electrical parameter, and then, based on the extracted depolarization current and polarization current values, obtain a ratio of the depolarization current to the polarization current.

[0101] Among them, the above-mentioned parallel equivalent circuit model can be a parallel equivalent circuit model that fits the dielectric.

[0102] Exemplarily, based on the first electrical parameter, a parallel equivalent circuit of the dielectric is fitted to obtain an equivalent resistance value R and a capacitance value C in the parallel equivalent circuit. Subsequently, the branch relaxation time τ is obtained by multiplying the equivalent resistance value R and the capacitance value C, where τ=R*C.

[0103] Exemplarily, the first electrical parameter includes depolarization measurement data and polarization measurement data. The main controller can accordingly extract the depolarization current value and the polarization current value from the first electrical parameter, and calculate the ratio of the depolarization current value to the polarization current value. The calculation formula can be R=i_depol(10s) / i_pol(100s).

[0104] Where R is the ratio of the depolarization current value to the polarization current value; i_depol(10s) is the depolarization current value, and i_pol(100s) is the polarization current value.

[0105] It should be understood that the branch relaxation time reflects the polarization response speed of XLPE insulation and is directly related to the mobility of the polymer molecular chains. The ratio of the depolarization current to the polarization current reflects the space charge dissipation capacity. After thermal aging, the increase in traps within the insulation slows the space charge dissipation rate.

[0106] In some embodiments, before determining the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current based on the first electrical parameter, the main controller may further filter the first electrical parameter to remove noise interference in the first electrical parameter.

[0107] The above-mentioned filtering may be a Savitzky-Golay filter. The Savitzky-Golay filter is used for signal smoothing. It effectively suppresses noise while retaining signal trends (such as peaks and inflection points). It is particularly suitable for processing signals with local linear or polynomial characteristics.

[0108] For example, Savitzky-Golay filtering is used to remove noise interference in actual measurement of the first electrical parameter. During the filtering process, the Savitzky-Golay filter can calculate a smoothed value at the center of the window by least squares fitting a polynomial within a sliding window. The size of the sliding window can be set to 21 points, and a third-order polynomial can be used for fitting.

[0109] It should be noted that the calculation of the above-mentioned branch relaxation time and the ratio of depolarization current to polarization current can be performed simultaneously; the branch relaxation time can also be calculated first, and then the ratio of depolarization current to polarization current is calculated; the ratio of depolarization current to polarization current can also be calculated first, and then the branch relaxation time is calculated. The embodiments of the present application do not limit this.

[0110] S203: Correct the second electrical parameter according to the temperature and humidity data to obtain a corrected second electrical parameter.

[0111] In this step, after determining the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current, the main controller can calibrate the second electrical parameter according to the temperature and humidity data to obtain the calibrated second electrical parameter.

[0112] In some embodiments, the main controller may first determine the corrected temperature of the environment in which the cable to be tested is located based on the temperature and humidity data. Subsequently, the main controller may perform temperature compensation on the second electrical parameter based on the corrected temperature to obtain a corrected second electrical parameter.

[0113] For example, the correction temperature can be calculated based on the detected temperature and humidity data and the reference temperature and humidity. If the reference temperature is 25°C and the reference relative humidity is 55%, the correction temperature can be calculated using formula (1).

[0114] (1)

[0115] in, is the corrected temperature, T is the temperature in the detected temperature and humidity data, is the humidity in the detected temperature and humidity data.

[0116] For example, the second electrical parameter can be corrected based on the correction temperature. The second electrical parameter includes the original frequency-domain dielectric loss data. By correcting the original frequency-domain dielectric loss data using the correction temperature, the corrected second electrical parameter temperature is the equivalent dielectric loss data after temperature compensation. The correction method can be shown in Formula (2).

[0117] (2)

[0118] Among them, tand is the equivalent dielectric loss data after temperature compensation, tand_means is the original frequency domain dielectric loss data, and T_comp is the correction temperature.

[0119] It should be noted that after compensation, the tand value at 50 Hz can be obtained as a quick reference value for the equivalent dielectric loss data after temperature compensation. Tand at 50 Hz is collected monthly to calculate the 12-month sliding average rate of change, eliminating seasonal temperature effects.

[0120] S204 : Determine the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift of the cable to be tested based on the corrected second electrical parameter.

[0121] In this step, after the main processor obtains the corrected second electrical parameter, it can determine the dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset of the cable to be tested based on the corrected second electrical parameter.

[0122] It should be understood that the above-mentioned dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset can all be obtained through the corrected second electrical parameter, and there is no restriction on the order of determining the dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset.

[0123] In some embodiments, the main processor may determine the frequency domain integral of the corrected second electrical parameter, and determine the dielectric loss frequency asymmetry based on the frequency domain integral of the corrected second electrical parameter.

[0124] Among them, dielectric loss frequency asymmetry is used to describe the degree to which the dielectric loss of an insulating material presents asymmetric characteristics within a symmetrical frequency range when the dielectric loss changes with frequency.

[0125] Exemplarily, the corrected second electrical parameter may be the temperature-compensated equivalent dielectric loss data tand. As shown in formula (3), the dielectric loss frequency asymmetry may be calculated using the frequency domain integral of the corrected second electrical parameter.

[0126] (3)

[0127] in, is the frequency domain integral of the equivalent dielectric loss data tand after temperature compensation in different frequency ranges f, is the dielectric loss angle, is the dielectric loss frequency asymmetry.

[0128] It should be understood that the presence of electrical trees in the cable makes the dielectric loss change nonlinearly in the high-frequency and low-frequency sections. The nonlinear change of the dielectric loss in the frequency domain is extracted by the difference of integrals, so that the dielectric loss frequency asymmetry can be determined.

[0129] In some embodiments, the main processor may perform logarithmic difference on the corrected second electrical parameter to obtain an imaginary part frequency curve of the dielectric constant, and perform least squares linear fitting on the imaginary part frequency curve of the dielectric constant to obtain a high-frequency polarization loss slope.

[0130] Among them, the high-frequency polarization loss slope can be the slope of the imaginary part of the dielectric constant in the high-frequency band (for example, 1 to 10 kHz), which can characterize the polarization relaxation intensity of the molecular chain segments of the insulating material and reflect the energy dissipation of the short-time relaxation process in the microstructure.

[0131] For example, the corrected second electrical parameter can be the temperature-compensated equivalent dielectric loss data tand, which can be logarithmically interpolated (for example, with 100 interpolation points per order of magnitude) to obtain a frequency curve of the imaginary part of the dielectric constant for subsequent calculations. Subsequently, a frequency curve of the imaginary part of the dielectric constant from 1 kHz to 10 kHz can be obtained and linearly fitted using the least squares method. This curve is then fitted to a linear function, and the slope of the linear function is obtained, which is used as the high-frequency polarization loss slope.

[0132] In some embodiments, the main processor may determine a quality factor corresponding to the cable to be detected based on the corrected second electrical parameter, and determine a quality factor peak offset corresponding to the quality factor.

[0133] The quality (Q) factor is a physical quantity that describes energy loss characteristics. A higher Q factor indicates lower system energy loss and better stability or quality.

[0134] For example, the Q factor is generally equal to the ratio of the energy storage capacity to the energy dissipation capacity of the medium, and can be numerically calculated by formula (4) through derivation.

[0135] (4)

[0136] For example, the frequency corresponding to the peak of the Q factor is the frequency at which the Q factor reaches its maximum value in the frequency domain. For new cables, the frequency corresponding to the peak of the Q factor is in the 3-4 kHz range. Cable aging changes the ratio of the dielectric's energy storage capacity to its energy dissipation capacity, causing the peak of the Q factor to shift. The peak shift of the Q factor, Δfq, can be expressed as Δfq = max Q(f) - f, where f is the frequency corresponding to the Q factor.

[0137] It should be understood that the Q-factor peak shift can be used in both the thermal aging and electrical tree aging assessment channels of cables. Thermal aging breaks the insulation's molecular chains, destroys the crystalline regions, and increases the insulation's equivalent resistance, shifting the Q-factor peak frequency toward higher frequencies. The Q-factor peak shift Δfq is positive. Electrical tree aging forms carbonized channels and enhances partial discharge, shifting the Q-factor peak frequency toward lower frequencies. The Q-factor peak shift Δfq is negative.

[0138] S205 , determining an insulation status test result of the cable to be tested based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift.

[0139] In this step, when the main controller determines the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset, the insulation status test result of the cable to be tested can be determined based on these characteristics.

[0140] In some embodiments, the main controller can generate a characteristic matrix for the insulation condition of the cable under test based on the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak shift. Subsequently, the main controller uses the characteristic matrix for the insulation condition of the cable under test to generate a thermal aging index and an electrical tree aging index for the cable under test. Finally, the main controller can determine the insulation condition test result of the cable under test based on the thermal aging index and the electrical tree aging index.

[0141] The thermal aging index can be a parameter indicating the extent to which the mechanical and dielectric properties of insulating materials deteriorate due to the intensified molecular thermal motion that leads to chemical structure destruction under long-term high temperature conditions.

[0142] The electrical tree aging index can be a parameter indicating the extent to which an insulating material, under the action of a local strong electric field, undergoes local breakdown of the material due to local discharge or electron ion bombardment, forming dendritic microchannels that gradually expand and eventually cause insulation breakdown.

[0143] Figure 4 A schematic diagram of feature fusion provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, by storing the branch relaxation time, depolarization current to polarization current ratio, dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak offset in a preset matrix, a characteristic matrix input for the insulation state is formed. Subsequently, the characteristic matrix for the insulation state is used as a diagnostic channel for thermal aging and electrical tree aging, respectively, to evaluate the two possible aging states and obtain the thermal aging index and electrical tree aging index of the cable under test.

[0144] For example, the thermal aging index can be calculated using formula (5), and the electrical tree aging index can be calculated using formula (6).

[0145] (5)

[0146] (6)

[0147] in, is the thermal aging index, is the branch relaxation time, 300 seconds, is the ratio of depolarization current to polarization current, is the quality factor peak shift, and is the weight coefficient, It can be 0.5, It can be 0.3, It can be 0.2. is the electrical tree aging index, is the high-frequency polarization loss slope, is the dielectric loss frequency asymmetry, 、 and is the weight coefficient, It can be 0.4, It can be 0.4, It can be 0.2.

[0148] It should be understood that after determining the thermal aging index and the electrical tree aging index, different methods may be used to determine the insulation status test result of the cable to be tested.

[0149] In some embodiments, the main controller may compare the thermal aging index with the thermal aging threshold to obtain a first comparison result. Furthermore, the main controller may compare the electrical tree aging index with the electrical tree aging threshold to obtain a second comparison result. Subsequently, the main controller may determine an insulation status detection result based on the first and second comparison results.

[0150] The aforementioned thermal aging threshold may be one or more. When there are multiple thermal aging thresholds, the first comparison results for different thermal aging thresholds may represent different insulation states. Correspondingly, the aforementioned electrical tree aging threshold may be one or more. When there are multiple electrical tree aging thresholds, the second comparison results for different electrical tree aging thresholds may also represent different insulation states.

[0151] Exemplarily, the thermal aging thresholds may include 0.3, 0.5, and 0.7, and the electrical tree aging thresholds may include 0.4, 0.6, and 0.8. If the first comparison result and the second comparison result show that the thermal aging index is greater than or equal to 0.7 and the electrical tree aging index is less than or equal to 0.4, then the insulation state detection result is that the cable insulation has been significantly aged, and thermal aging is dominant. If the first comparison result and the second comparison result show that the thermal aging index is less than or equal to 0.3 and the electrical tree aging index is greater than or equal to 0.8, then the insulation state detection result is that the cable insulation has been significantly aged, and electrical tree aging is dominant. If the first comparison result and the second comparison result show that the thermal aging index is greater than or equal to 0.5 and the electrical tree aging index is greater than or equal to 0.6, then the insulation state detection result is that the cable insulation is mixed aging.

[0152] In other embodiments, the main controller may calculate health parameters of the cable to be tested based on the thermal aging index and the electrical tree aging index, and then determine the insulation status test result of the cable to be tested based on the health parameters.

[0153] For example, the health parameter of the cable to be tested can be calculated using formula (7).

[0154] (7)

[0155] in, is the health parameter of the cable to be tested, is the thermal aging index, is the electrical tree aging index, In order to dynamically adjust the contribution of thermoelectric factors in fusion, .

[0156] It should be understood that different values ​​of the health parameters of the cable to be tested can represent different insulation status test results.

[0157] For example, if the value of the health parameter is between 0.85 and 1, it indicates that the insulation state is healthy, and only routine monitoring is required in the future. If the value of the health parameter is between 0.70 and 0.84, it indicates that the insulation state is sub-healthy, and subsequent inspections need to be strengthened. If the value of the health parameter is between 0.50 and 0.69, it indicates that the insulation state is in the initial stage of aging, and annual assessment is required in the future. If the value of the health parameter is between 0.30 and 0.49, it indicates that the insulation state is accelerated aging, and quarterly assessment is required in the future. If the value of the health parameter is less than 0.3, it indicates that the insulation state is critical failure, and immediate replacement is required.

[0158] It should be understood that after the insulation status test result is determined, historical data can be combined to determine whether the test result has changed suddenly. If the test result is not sudden, the test result is determined to be valid. If the test result has changed suddenly, the data recovery mechanism is activated to automatically retrieve the previous insulation status test result for review and comparison.

[0159] In some embodiments, if during the detection process, the main processor determines that the insulation status detection result is abnormal (sub-health, initial aging, accelerated aging, critical failure), in addition to generating a detailed detection report, it will also immediately issue an alarm to notify relevant personnel to handle it in a timely manner.

[0160] The cable insulation status detection method provided in the embodiment of the present application avoids the errors and inefficiencies of manual operation, can quickly and accurately obtain cable insulation parameters, ensure the stability of test conditions, and is not affected by factors such as the external environment. It can actively select the type of test voltage and customize the measurement time and interval threshold. In addition, because data acquisition and analysis are automatically performed by the main controller, the accuracy and efficiency of detection are greatly improved, and the errors of manual analysis data are reduced. It can automatically complete the AC / DC switching and measurement process without manual operation, improve the real-time and continuity of detection, and can promptly detect potential cable insulation problems.

[0161] The cable insulation status detection method provided in the embodiment of the present application obtains the first electrical parameter, the second electrical parameter and temperature and humidity data of the cable to be detected, where the first electrical parameter is the DC polarization and depolarization electrical parameter corresponding to the DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is the AC high-frequency dielectric spectrum parameter corresponding to the AC voltage source detection circuit of the cable to be detected; based on the first electrical parameter, the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current are determined; based on the temperature and humidity data, the second electrical parameter is corrected to obtain the corrected second electrical parameter; based on the corrected second electrical parameter, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset of the cable to be detected are determined; based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset, the insulation status detection result of the cable to be detected is determined. By obtaining the DC polarization and depolarization electrical parameters corresponding to the DC voltage source detection circuit and the AC high-frequency dielectric spectrum parameters corresponding to the AC voltage source detection circuit, the branch relaxation time, the ratio of depolarization current to polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset, which are characteristics related to the insulation state, are determined. Based on these characteristics related to the insulation state, the insulation state detection result of the cable to be tested is determined, thereby eliminating the need for manual inspection and enabling real-time data collection and calculation, thereby realizing real-time monitoring of the cable insulation state.

[0162] Figure 5 A flow chart of another method for detecting the insulation status of a cable provided in an embodiment of the present application is shown as follows: Figure 5 As shown, the method for detecting the insulation status of the cable includes S301-S309:

[0163] S301: Acquire first electrical parameters, second electrical parameters, and temperature and humidity data of a cable to be tested.

[0164] The first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected.

[0165] S302: Determine the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current according to the first electrical parameter.

[0166] S303: Correct the second electrical parameter according to the temperature and humidity data to obtain a corrected second electrical parameter.

[0167] S304 : Determine the dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak shift of the cable to be tested based on the corrected second electrical parameter.

[0168] S305 , generating a characteristic matrix of the insulation state of the cable to be tested according to the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift.

[0169] S306 : Generate a thermal aging index and an electrical tree aging index of the cable to be tested using a characteristic matrix of the insulation state of the cable to be tested.

[0170] S307: Compare the thermal aging index and the thermal aging threshold to obtain a first comparison result.

[0171] S308 : Compare the electrical tree aging index and the electrical tree aging threshold to obtain a second comparison result.

[0172] S309: Determine an insulation status detection result according to the first comparison result and the second comparison result.

[0173] Figure 6 A flow chart of another method for detecting the insulation status of a cable provided in an embodiment of the present application is shown as follows: Figure 6 As shown, the method for detecting the insulation status of the cable includes S401-S408:

[0174] S401: Acquire first electrical parameters, second electrical parameters, and temperature and humidity data of a cable to be tested.

[0175] The first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected.

[0176] S402: Determine the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current according to the first electrical parameter.

[0177] S403: Correct the second electrical parameter according to the temperature and humidity data to obtain a corrected second electrical parameter.

[0178] S404 : Determine the dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak shift of the cable to be tested based on the corrected second electrical parameter.

[0179] S405 , generating a characteristic matrix of the insulation state of the cable to be tested according to the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift.

[0180] S406 , using the characteristic matrix of the insulation state of the cable to be tested, generating a thermal aging index and an electrical tree aging index of the cable to be tested.

[0181] S407: Calculate the health parameter of the cable to be tested according to the thermal aging index and the electrical tree aging index.

[0182] S408: Determine the insulation status test result of the cable to be tested according to the health parameter.

[0183] The cable insulation status detection method provided in the embodiment of the present application obtains the first electrical parameter, the second electrical parameter and temperature and humidity data of the cable to be detected, where the first electrical parameter is the DC polarization and depolarization electrical parameter corresponding to the DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is the AC high-frequency dielectric spectrum parameter corresponding to the AC voltage source detection circuit of the cable to be detected; based on the first electrical parameter, the branch relaxation time of the cable to be detected and the ratio of the depolarization current to the polarization current are determined; based on the temperature and humidity data, the second electrical parameter is corrected to obtain the corrected second electrical parameter; based on the corrected second electrical parameter, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset of the cable to be detected are determined; based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset, the insulation status detection result of the cable to be detected is determined. By obtaining the DC polarization and depolarization electrical parameters corresponding to the DC voltage source detection circuit and the AC high-frequency dielectric spectrum parameters corresponding to the AC voltage source detection circuit, the branch relaxation time, the ratio of depolarization current to polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset, which are characteristics related to the insulation state, are determined. Based on these characteristics related to the insulation state, the insulation state detection result of the cable to be tested is determined, thereby eliminating the need for manual inspection and enabling real-time data collection and calculation, thereby realizing real-time monitoring of the cable insulation state.

[0184] It should be understood that, although the steps in the flowcharts of the above embodiments are shown in sequence as indicated by the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be performed in other orders. Moreover, at least a portion of the steps in the flowcharts of the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily to be performed in sequence, but can be performed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0185] Based on the same inventive concept, embodiments of the present application further provide a device for detecting the insulation state of a cable, for implementing the aforementioned method for detecting the insulation state of a cable. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the device for detecting the insulation state of a cable provided below can be found in the aforementioned definition of the method for detecting the insulation state of a cable, and will not be further elaborated here.

[0186] In an exemplary embodiment, Figure 7 As shown, a device 500 for detecting the insulation status of a cable is provided, comprising: an acquisition module 501, a feature determination module 502 and a detection module 503, wherein:

[0187] An acquisition module 501 is configured to acquire a first electrical parameter, a second electrical parameter, and temperature and humidity data of the cable to be tested, wherein the first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be tested, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be tested;

[0188] Feature determination module 502 is configured to determine, based on the first electrical parameter, a branch relaxation time and a ratio of a depolarization current to a polarization current of the cable to be tested; calibrate the second electrical parameter based on the temperature and humidity data to obtain a calibrated second electrical parameter; and determine, based on the calibrated second electrical parameter, a dielectric loss frequency asymmetry, a high-frequency polarization loss slope, and a quality factor peak shift of the cable to be tested;

[0189] The detection module 503 is used to determine the insulation status detection result of the cable to be detected based on the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset.

[0190] In one embodiment, the feature determination module 502 is further used to input the first electrical parameter into a parallel equivalent circuit model to determine the equivalent resistance value and capacitance value of the cable to be detected; determine the branch relaxation time based on the equivalent resistance value and capacitance value; extract the depolarization current value and polarization current value of the cable to be detected from the first electrical parameter; and obtain the ratio of the depolarization current to the polarization current based on the extracted depolarization current value and polarization current value.

[0191] In one embodiment, the acquisition module 501 is further configured to filter the first electrical parameter to remove noise interference in the first electrical parameter.

[0192] In one embodiment, the feature determination module 502 is further configured to determine a correction temperature of the environment in which the cable to be detected is located based on the temperature and humidity data; and perform temperature compensation on the second electrical parameter based on the correction temperature to obtain a corrected second electrical parameter.

[0193] In one embodiment, the feature determination module 502 is further used to determine the frequency domain integral of the corrected second electrical parameter, and determine the dielectric loss frequency asymmetry based on the frequency domain integral of the corrected second electrical parameter; perform logarithmic difference on the corrected second electrical parameter to obtain the imaginary part frequency curve of the dielectric constant, and perform least squares linear fitting on the imaginary part frequency curve of the dielectric constant to obtain the high-frequency polarization loss slope; determine the quality factor corresponding to the cable to be tested based on the corrected second electrical parameter, and determine the quality factor peak offset corresponding to the quality factor.

[0194] In one embodiment, the detection module 503 is further used to generate a characteristic matrix of the insulation state of the cable to be detected based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope and the quality factor peak offset; use the characteristic matrix of the insulation state of the cable to be detected to generate a thermal aging index and an electrical tree aging index of the cable to be detected; and determine the insulation state detection result of the cable to be detected based on the thermal aging index and the electrical tree aging index.

[0195] In one embodiment, the detection module 503 is further configured to compare the thermal aging index with the thermal aging threshold to obtain a first comparison result; compare the electrical tree aging index with the electrical tree aging threshold to obtain a second comparison result; and determine the insulation state detection result based on the first comparison result and the second comparison result.

[0196] In one embodiment, the detection module 503 is configured to calculate health parameters of the cable to be detected based on the thermal aging index and the electrical tree aging index; and determine the insulation status detection result of the cable to be detected based on the health parameters.

[0197] Each module in the aforementioned cable insulation status detection device can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0198] In an exemplary embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 8 As shown. The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner. The wireless manner can be achieved through WIFI, a mobile cellular network, near field communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a method for detecting the insulation status of a cable.

[0199] Those skilled in the art will understand that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0200] In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the above-mentioned method for detecting the insulation status of a cable when executing the computer program.

[0201] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method for detecting the insulation status of the cable is implemented.

[0202] In one embodiment, a computer program product is provided, comprising a computer program, which implements the above-mentioned method for detecting the insulation status of a cable when executed by a processor.

[0203] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), quantum computing-based data processing logic devices, artificial intelligence (AI) processors, and the like.

[0204] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0205] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for detecting the insulation status of a cable, characterized in that: The method comprises: Acquire a first electrical parameter, a second electrical parameter, and temperature and humidity data of the cable to be detected, wherein the first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected; Determining, based on the first electrical parameter, a branch relaxation time and a ratio of a depolarization current to a polarization current of the cable to be detected; Correcting the second electrical parameter according to the temperature and humidity data to obtain a corrected second electrical parameter; Determining the dielectric loss frequency asymmetry, high-frequency polarization loss slope, and quality factor peak shift of the cable to be tested based on the corrected second electrical parameter; The insulation state detection result of the cable to be detected is determined according to the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset.

2. The method according to claim 1, characterized in that Determining the branch relaxation time and the ratio of the depolarization current to the polarization current of the cable to be detected based on the first electrical parameter includes: Inputting the first electrical parameter into a parallel equivalent circuit model to determine the equivalent resistance and capacitance of the cable to be tested; Determining the branch relaxation time according to the equivalent resistance value and the capacitance value; Extracting the depolarization current value and the polarization current value of the cable to be tested from the first electrical parameter; The ratio of the depolarization current to the polarization current is obtained according to the extracted depolarization current value and polarization current value.

3. The method according to claim 1 or 2, characterized in that Before determining the branch relaxation time and the ratio of the depolarization current to the polarization current of the cable to be detected based on the first electrical parameter, the method further includes: The first electrical parameter is filtered to remove noise interference in the first electrical parameter.

4. The method according to claim 1, wherein The step of correcting the second electrical parameter according to the temperature and humidity data to obtain the corrected second electrical parameter includes: Determining the corrected temperature of the environment where the cable to be tested is located based on the temperature and humidity data; The second electrical parameter is temperature compensated according to the correction temperature to obtain the corrected second electrical parameter.

5. The method according to claim 1, characterized in that Determining the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift of the cable to be tested based on the corrected second electrical parameter includes: Determining the frequency domain integral of the corrected second electrical parameter, and determining the dielectric loss frequency asymmetry based on the frequency domain integral of the corrected second electrical parameter; Performing logarithmic difference on the corrected second electrical parameter to obtain a dielectric constant imaginary part frequency curve, and performing least squares linear fitting on the dielectric constant imaginary part frequency curve to obtain the high-frequency polarization loss slope; The quality factor corresponding to the cable to be detected is determined according to the corrected second electrical parameter, and a quality factor peak offset corresponding to the quality factor is determined.

6. The method according to claim 1, characterized in that Determining the insulation status detection result of the cable to be detected based on the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak offset includes: Generate a characteristic matrix of the insulation state of the cable to be tested according to the branch relaxation time, the ratio of the depolarization current to the polarization current, the dielectric loss frequency asymmetry, the high-frequency polarization loss slope, and the quality factor peak shift; Generate a thermal aging index and an electrical tree aging index of the cable to be tested using a characteristic matrix of the insulation state of the cable to be tested; The insulation state detection result of the cable to be detected is determined according to the thermal aging index and the electrical tree aging index.

7. The method according to claim 6, characterized in that The step of determining the insulation state test result of the cable to be tested according to the thermal aging index and the electrical tree aging index includes: Comparing the thermal aging index with a thermal aging threshold to obtain a first comparison result; comparing the electrical tree aging index with an electrical tree aging threshold to obtain a second comparison result; The insulation state detection result is determined according to the first comparison result and the second comparison result.

8. The method according to claim 6, characterized in that The step of determining the insulation state test result of the cable to be tested according to the thermal aging index and the electrical tree aging index includes: Calculating the health parameter of the cable to be tested according to the thermal aging index and the electrical tree aging index; An insulation status detection result of the cable to be detected is determined according to the health parameter.

9. A device for detecting the insulation status of a cable, characterized in that: The device comprises: an acquisition module, configured to acquire a first electrical parameter, a second electrical parameter, and temperature and humidity data of the cable to be detected, wherein the first electrical parameter is a DC polarization and depolarization electrical parameter corresponding to a DC voltage source detection circuit of the cable to be detected, and the second electrical parameter is an AC high-frequency dielectric spectrum parameter corresponding to an AC voltage source detection circuit of the cable to be detected; a feature determination module, configured to determine, based on the first electrical parameter, a branch relaxation time and a ratio of a depolarization current to a polarization current of the cable to be detected; correct the second electrical parameter based on the temperature and humidity data to obtain a corrected second electrical parameter; and determine, based on the corrected second electrical parameter, a dielectric loss frequency asymmetry, a high-frequency polarization loss slope, and a quality factor peak offset of the cable to be detected; The detection module is used to determine the insulation status detection result of the cable to be detected based on the branch relaxation time, the ratio of depolarization current to polarization current, dielectric loss frequency asymmetry, high-frequency polarization loss slope and quality factor peak offset.

10. A cable insulation status detection system, characterized in that: The cable insulation status detection system includes: a main controller, an auxiliary controller, a timer, a high-voltage switch, a DC voltage source, an AC voltage source, an electrical parameter detection device and a temperature and humidity sensor; The main controller is connected to the temperature and humidity sensor, the electrical parameter detection device, the high-voltage switch and the auxiliary controller respectively; the high-voltage switch is connected to the DC voltage source and the AC voltage source; the auxiliary controller is connected to the timer; The main controller is configured to execute the method for detecting the insulation status of a cable according to any one of claims 1 to 8; The high-voltage switch is used to switch between the DC voltage source or the AC voltage source to form a DC voltage source detection loop or an AC voltage source detection loop on the cable to be tested; The electrical parameter detection device is used to detect a first electrical parameter when forming a DC voltage source detection loop, and to detect a second electrical parameter when forming an AC voltage source detection loop; The temperature and humidity sensor is used to detect the temperature and humidity of the environment where the cable to be tested is located; The auxiliary controller is used to cooperate with the timer to control the working sequence of each device in the cable insulation status detection system.

Images