Online monitoring method and system for high-voltage cable harmonic signal abnormity

Abstract

The invention discloses an online monitoring method and system for high-voltage cable harmonic signal abnormity, and belongs to the technical field of state monitoring and aging evaluation. The online monitoring method comprises the following steps: measuring a harmonic signal of a to-be-measured high-voltage cable through a non-contact harmonic signal sensor to obtain a non-contact harmonic signal; sampling the non-contact harmonic signal, and calculating according to the sampled non-contact harmonic signal to obtain a value of a key quantitative index; and determining whether the harmonic signal of the high-voltage cable is abnormal based on the value of the key quantitative index. On-line measurement can be achieved, the cable does not need to be powered off, and use is convenient. The technical means is convenient, and the harmonic signal detection result can be analyzed in real time according to the on-site actual situation.

Description

Technical Field

[0001] The present invention relates to the technical field of condition monitoring and aging assessment, and more specifically, to an online monitoring method and system for abnormal harmonic signals of high-voltage cables. Background Art

[0002] In recent years, with the rapid development of the online monitoring technology for high-voltage cable lines, a visual comprehensive monitoring system covering partial discharge of the cable body, temperature monitoring, grounding current detection, early warning of external force damage to the channel, and environmental parameter monitoring has been gradually constructed. However, there are still significant technical blind spots in the existing monitoring technology for cable conductor defect identification, insulation status assessment, and abnormal detection of the grounding system, specifically manifested as: ① insufficient sensitivity for identifying latent defects; ② low accuracy of working condition early warning; ③ lack of dynamic monitoring ability for insulation degradation in a broadband disturbance environment. Especially under the operating conditions of a new power system, high-voltage cables are long-term exposed to broadband electromagnetic disturbances, resulting in a significant increase in the risk of accelerated aging of insulation materials, which poses higher requirements for the potential risk perception technology of cable lines.

[0003] Existing papers and materials confirm that there is a significant correlation between the abnormal characteristics of cable harmonic signals and the insulation degradation process and potential defects. However, the current research results mainly focus on the theoretical analysis of the abnormal mechanism of harmonic components, and an online monitoring system solution for high-voltage cable harmonic signals applicable to the engineering site has not been established, restricting the practical application of this technology. Summary of the Invention

[0004] In view of the above problems, the present invention proposes an online monitoring method for abnormal harmonic signals of high-voltage cables, including:

[0005] Measuring the harmonic signals of the high-voltage cable to be measured through a non-contact harmonic signal sensor to obtain non-contact harmonic signals;

[0006] Sampling the non-contact harmonic signals, and calculating according to the sampled non-contact harmonic signals to obtain the values of key quantization indexes;

[0007] Based on the values of the key quantization indexes, determining whether the harmonic signals of the high-voltage cable are abnormal.

[0008] Optionally, the non-contact harmonic signal sensor is arranged at a preset measurement point of the high-voltage cable to be measured;

[0009] The preset measurement point is set within the grounding areas at both ends of the grounding wire of the high-voltage cable to be measured, at a position 5-10 cm away from the grounding wire.

[0010] Optionally, based on the synchronous transmission protocol of optical fiber medium, transmit the sampled non-contact harmonic signals.

[0011] Optionally, the key quantitative indicators include:

[0012] The root mean square (RMS) value of harmonic current, total harmonic distortion (THD) rate, defective harmonic content, and relative harmonic content.

[0013] Optionally, the calculation formula for the value of the RMS value of harmonic current is as follows:

[0014]

[0015] Where, I RMS is the value of the RMS value of harmonic current, and I1…I n are the RMS values of the fundamental wave and the 2nd to nth harmonics respectively.

[0016] Optionally, the calculation formula for the value of the THD rate is as follows:

[0017]

[0018] Where, THD I is the value of the THD rate, and I1…I n are the RMS values of the fundamental wave and the 2nd to nth harmonics respectively.

[0019] Optionally, the calculation formula for the value of the individual harmonic content is as follows:

[0020]

[0021] Where, K n is the value of the defective harmonic content, and I1 and I n are the RMS values of the fundamental wave and the 2nd and nth harmonics respectively.

[0022] Optionally, the calculation formula for the value of the relative harmonic content is as follows:

[0023]

[0024] Where, R n is the value of the relative harmonic content, K n is the value of the defective harmonic content, K n * is the nth harmonic content of the cable without defects.

[0025] On the other hand, the present invention also proposes an on-line monitoring system for abnormal harmonic signals of high-voltage cables, including: a non-contact harmonic signal sensor, a collection module, a data transmission module, and a data analysis and processing module;

[0026] The non-contact harmonic signal sensor is used to measure the harmonic signal of the high-voltage cable to be measured and obtain the non-contact harmonic signal. The acquisition module is used to sample the non-contact harmonic signal and transmit the sampled non-contact harmonic signal to the data analysis and processing module through the data transmission module. The data analysis and processing is used to calculate based on the sampled non-contact harmonic signal to obtain the value of the key quantization index, and determine whether the harmonic signal of the high-voltage cable is abnormal based on the value of the key quantization index.

[0027] Optionally, the non-contact harmonic signal sensor is arranged at a preset measurement point of the high-voltage cable to be measured;

[0028] The preset measurement point is set within the grounding area at both ends of the grounding wire of the high-voltage cable to be measured, at a position 5-10 cm away from the grounding wire.

[0029] Optionally, between the acquisition module and the data transmission module, based on the synchronous transmission protocol of the optical fiber medium, the sampled non-contact harmonic signal is transmitted.

[0030] Optionally, the key quantization index includes:

[0031] The root mean square (RMS) value of the harmonic current, the total harmonic distortion (THD) rate, the defective harmonic content, and the relative harmonic content.

[0032] Optionally, the calculation formula for the value of the root mean square (RMS) value of the harmonic current is as follows:

[0033]

[0034] Where, I RMS is the value of the root mean square (RMS) value of the harmonic current, and I1…I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

[0035] Optionally, the calculation formula for the value of the total harmonic distortion (THD) rate is as follows:

[0036]

[0037] Where, THD I is the value of the total harmonic distortion (THD) rate, and I1…I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

[0038] Optionally, the calculation formula for the value of the individual harmonic content is as follows:

[0039]

[0040] Where, K n is the value of the defective harmonic content, and I1 and I nThey are the effective values of the fundamental wave, the second harmonic wave, and the nth harmonic wave respectively.

[0041] Optionally, the calculation formula for the value of the relative harmonic content is as follows:

[0042]

[0043] where R n is the value of the relative harmonic content, and K n is the value of the defective harmonic content, and K n * is the nth harmonic content of the cable without defects.

[0044] On the other hand, the present invention also provides a computing device, including: one or more processors;

[0045] The processor is used to execute one or more programs;

[0046] When the one or more programs are executed by the one or more processors, the method as described above is implemented.

[0047] On the other hand, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed, the method as described above is implemented.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] The present invention proposes an online monitoring method for abnormal harmonic signals of high-voltage cables, including: measuring harmonic signals of a high-voltage cable to be measured through a non-contact harmonic signal sensor to obtain non-contact harmonic signals; sampling the non-contact harmonic signals, calculating according to the sampled non-contact harmonic signals, and obtaining the values of key quantization indicators; based on the values of the key quantization indicators, determining whether the harmonic signals of the high-voltage cable are abnormal. The present invention can realize online measurement, the cable does not need to be powered off, and it is convenient to use. The technical means of the present invention is convenient, and the detection results of harmonic signals can be analyzed in real time according to the actual situation on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flowchart of the method of the present invention;

[0051] Figure 2 is a structural diagram of the system of the present invention;

[0052] Figure 3 is a schematic diagram of measuring harmonic signals of a high-voltage cable in an embodiment of the system of the present invention;

[0053] Figure 4 is a schematic cross-sectional view of a non-contact harmonic signal sensor in an embodiment of the system of the present invention;

[0054] Figure 5 Schematic diagram of the metal sheath and harmonic sensor coil in the system embodiment of the present invention;

[0055] Figure 6 Schematic diagram of the integral correction circuit in the system embodiment of the present invention;

[0056] Figure 7 Schematic diagram of the on - line monitoring method and system in the system embodiment of the present invention;

[0057] Figure 8 Schematic diagram of the detection result of harmonic signals of a case high - voltage cable in the system embodiment of the present invention;

[0058] Figure 9 Schematic diagram of the analysis and processing result of harmonic signals of a case high - voltage cable in the system embodiment of the present invention. Detailed implementation manners

[0059] Now, refer to the accompanying drawings to introduce the exemplary embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not limitations on the present invention. In the drawings, the same units / components are denoted by the same reference numerals.

[0060] Unless otherwise specified, the terms (including scientific and technical terms) used herein have the ordinary meaning understood by those skilled in the art. In addition, it can be understood that the terms defined in the commonly used dictionary should be understood to have a meaning consistent with the context of their related fields, and should not be understood as idealized or overly formal meanings.

[0061] Embodiment 1:

[0062] The present invention proposes an on - line monitoring method for abnormal harmonic signals of high - voltage cables, as Figure 1 shown, including:

[0063] Step 1: Measure the harmonic signals of the high - voltage cable to be measured through a non - contact harmonic signal sensor to obtain non - contact harmonic signals;

[0064] Step ②: Sample the non - contact harmonic signals, calculate according to the sampled non - contact harmonic signals, and obtain the values of key quantization indicators;

[0065] Step ③: Based on the values of the key quantization indicators, determine whether the harmonic signals of the high - voltage cable are abnormal.

[0066] Among them, the non-contact harmonic signal sensor is arranged at a preset measurement point of the high-voltage cable to be measured;

[0067] The preset measurement point is set within the grounding area at both ends of the grounding wire of the high-voltage cable to be measured, at a position 5 - 10 cm away from the grounding wire.

[0068] Among them, based on the synchronous transmission protocol of optical fiber medium, the sampled non-contact harmonic signal is transmitted.

[0069] Among them, the key quantization indicators include:

[0070] The effective value of harmonic current RMS, total harmonic distortion rate THD, defective harmonic content, and relative harmonic content.

[0071] Among them, the calculation formula for the value of the effective value of harmonic current RMS is as follows: [[ID=1 7]]

[0072]

[0073] Among them, I RMS is the value of the effective value of harmonic current RMS, and I1…I n are the effective values of the fundamental wave and the 2nd to the nth harmonics respectively.

[0074] Among them, the calculation formula for the value of the total harmonic distortion rate THD is as follows:

[0075]

[0076] Among them, THD I is the value of the total harmonic distortion rate THD, and I1…I n are the effective values of the fundamental wave and the 2nd to the nth harmonics respectively.

[0077] Among them, the calculation formula for the value of the individual harmonic content is as follows:

[0078]

[0079] Among them, K n is the value of the defective harmonic content, and I1 and I n are the effective values of the fundamental wave and the 2nd and the nth harmonics respectively.

[0080] Among them, the calculation formula for the value of the relative harmonic content is as follows:

[0081]

[0082] Among them, R n is the value of the relative harmonic content, K n is the value of the defective harmonic content, and K n * is the nth harmonic content of the cable without defects.

[0083] Example 2:

[0084] The present invention also proposes an on-line monitoring system for abnormal harmonic signals of high-voltage cables, as Figure 2 shown, including: a non-contact harmonic signal sensor, an acquisition module, a data transmission module, and a data analysis and processing module;

[0085] The non-contact harmonic signal sensor is used to measure the harmonic signal of the high-voltage cable to be measured, and obtain the non-contact harmonic signal. The acquisition module is used to sample the non-contact harmonic signal, and transmit the sampled non-contact harmonic signal to the data analysis and processing module through the data transmission module. The data analysis and processing is used to calculate according to the sampled non-contact harmonic signal, obtain the value of the key quantization index, and determine whether the harmonic signal of the high-voltage cable is abnormal based on the value of the key quantization index.

[0086] Among them, the non-contact harmonic signal sensor is arranged at a preset measurement point of the high-voltage cable to be measured;

[0087] The preset measurement point is set within the grounding area at both ends of the grounding wire of the high-voltage cable to be measured, at a position 5-10 cm away from the grounding wire.

[0088] Among them, between the acquisition module and the data transmission module, based on the synchronous transmission protocol of the optical fiber medium, the sampled non-contact harmonic signal is transmitted.

[0089] Among them, the key quantization index includes:

[0090] The effective value of harmonic current RMS, the total harmonic distortion rate THD, the defective harmonic content, and the relative harmonic content.

[0091] Among them, the calculation formula for the value of the effective value of harmonic current RMS is as follows:

[0092]

[0093] Among them, I RMS is the value of the effective value of harmonic current RMS, O1…I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

[0094] Among them, the calculation formula for the value of the total harmonic distortion rate THD is as follows:

[0095]

[0096] Among them, THD I is the value of the total harmonic distortion rate THD, I1…I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

[0097] Among them, the calculation formula for the value of the individual harmonic content is as follows:

[0098]

[0099] Among them, K n is the value of the defective harmonic content, and I1 and I n are the effective values of the fundamental wave and the 2nd and nth harmonics respectively.

[0100] Among them, the calculation formula for the value of the relative harmonic content is as follows:

[0101]

[0102] Among them, R n is the value of the relative harmonic content, K n is the value of the defective harmonic content, K n * is the nth harmonic content of the cable without defects.

[0103] The present invention will be further described below in conjunction with specific cases:

[0104] First, the measurement method of the harmonic signal will be described:

[0105] In view of the typical structural characteristics of the double-end grounding of the high-voltage cable system, this system adopts a non-contact measurement scheme, and its topological structure is as Figure 3 shown. The measurement points are set at both ends of the grounding area (x = 0 and x = L) of the cable grounding wire (length L), and harmonic sensors are deployed at a position 5-10 cm away from the grounding wire to realize long-term monitoring of the amplitude-frequency characteristics of the harmonic current of the metal sheath.

[0106] The non-contact harmonic signal sensor adopts a composite magnetic core structure design and is composed of ferrite, multi-turn coil, analog data acquisition board, battery and shell, etc., as Figure 4 shown. The coil radius r, magnetic permeability μ, number of coil turns N, coil resistance R of the harmonic sensor, the distance a between the sensor and the wire, the distance x between the coil and the wire, and ω is the angular frequency of the sheath current, as Figure 5 shown.

[0107] When the cable sheath current I in = I m cos(ωt) passes through, the induced voltage V in in the coil of the sensor is:

[0108]

[0109] V inis the differential form of the cable sheath current signal. To avoid the induction of an excessively high output voltage at the output end of the coil by minor high-frequency components, which would then cause the signal to be submerged, the induced voltage of the sensor coil is restored through an integration correction circuit, as Figure 6 shown, to obtain the output voltage V out of the coil and the current signal I out as follows:

[0110]

[0111] The on-line monitoring system for harmonic signals includes a non-contact harmonic signal sensor, an acquisition module, a data transmission module, a data analysis and processing module, a storage device, a power management module, and a display module, as Figure 7 shown.

[0112] The signal acquisition module includes a digital signal processor (DSP) with a sampling rate set at 51.2 KHz, that is, there are 1024 sampling points in each cycle waveform. This DSP uses a 16-bit synchronous sampling A / D conversion chip, which can achieve high-precision, fast response, and synchronous sampling of the harmonic signals from the harmonic signal sensor. In addition, to eliminate the measurement data errors that may be caused by measurement frequency deviations, this module uses a phase-locked loop technology combining software and hardware for automatic frequency tracking (±0.01 Hz frequency tracking accuracy) and real-time adjustment of the sampling interval, avoiding the phenomenon of frequency leakage. After the digital signal acquisition is completed, the data transmission module, based on the synchronous transmission protocol of optical fiber medium, transmits the monitoring data to the data analysis and processing module, achieving a signal time delay < 1 μs.

[0113] The data analysis and processing module uses a microprocessor with an advanced reduced instruction set machine (ARM) architecture for data calculation, statistics, display, and storage, and is controlled through the Linux embedded operating system as a software platform. This module performs windowed Fourier analysis on the collected harmonic signals of high-voltage cables, extracts the 2 - 20th harmonic current data from the measured signals, observes the amplitude-frequency characteristics of specific harmonic currents, determines the setting value of the amplification factor, and analyzes the abnormal degree of harmonics in the metal sheath of high-voltage cables by calculating key quantization indicators of harmonic currents such as the root mean square (RMS) value of harmonic current, total harmonic distortion (THD), individual harmonic content (K n ) and relative harmonic content (R n ), and then evaluates the degree of insulation deterioration of the cable. Among them:

[0114] The window function samples of the Hanning window are:

[0115]

[0116] i ω (n) = i(n)·ω(n) (5)

[0117] The spectrum of the measured harmonic signal sample after windowed Fourier analysis is as follows:

[0118]

[0119] The effective value of harmonic current is a physical quantity characterizing the magnitude of alternating current, reflecting the total heating effect of the current containing fundamental wave and harmonic components.

[0120]

[0121] The total harmonic distortion rate reflects the ratio of the amplitudes of all harmonic currents to the amplitude of the fundamental wave current. Its calculation formula is:

[0122]

[0123] The individual harmonic content refers to the magnitude of the harmonic current of a single frequency. They are usually used to analyze the specific impact of harmonics at specific frequencies on the system. I1, I2, ···, I n , are the effective values of the fundamental wave and the 2nd to the nth harmonics respectively, N is the upper limit of the harmonic order, K n and K n * are the nth harmonic contents of the defective and non-defective cables respectively, and R n is the relative harmonic content of the defective sample cable.

[0124]

[0125] The relative harmonic content refers to the ratio of the nth harmonic of the defective cable to that of the non-defective cable, and is used to characterize the impact of the defect on the induced current in the metal shielding layer of the cable under the same measurement conditions.

[0126]

[0127] The display module provides a user interaction interface, enabling intuitive and convenient operation of the device, display of test results, and adjustment of test parameters. In addition, the power management module is equipped with a 2000 mAh lithium battery, providing a stable and reliable power supply, enabling the device to operate stably for 24 hours in an environment without an external power supply.

[0128] The on-line monitoring method and system for harmonic signals can provide efficient and accurate harmonic signal monitoring functions on-site through the cooperation of the above highly integrated and precise hardware components. After calibration, the measured accuracy of the device is shown in Table 1, meeting the requirements of National Standard Class A for harmonic signal monitoring indicators, and can be well applied to the on-line monitoring and analysis of abnormal harmonic signals of high-voltage cables.

[0129] Table 1

[0130]

[0131] The present invention can achieve on-line measurement, without the need to cut off the power supply of the cable, and is convenient to use.

[0132] The technical means of the present invention are convenient, and the detection results of harmonic signals can be analyzed in real time according to the actual situation on site.

[0133] Through on-site measurement verification of a 150m long cross-linked polyethylene high-voltage cable in a 220kV transmission line, this system continuously monitors the harmonic current signals of the metal sheath of the grounding wires (x = 0 / L) at both ends of the cable under different load conditions. Figure 8 The harmonic current spectrum i(f) captured under typical working conditions is shown. After processing by windowed Fourier transform and Hanning window function, as Figure 9 shown, it is found that the amplitudes of the 3rd (150Hz), 5th (250Hz), and 7th (350Hz) harmonic components are significantly higher, indicating that there may be latent defects in the insulation of this cable.

[0134] Embodiment 3:

[0135] [[ID=ID=19]]Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory. The memory is used to store a computer program, and the computer program includes program instructions. The processor is used to execute the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the method in the above embodiments.

[0136] Embodiment 4:

[0137] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device, used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and, of course, the extended storage medium supported by the computer device. The computer-readable storage medium provides a storage space, and this storage space stores the operating system of the terminal. And, in this storage space, there are also stored one or more instructions suitable for being loaded and executed by the processor. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. One or more instructions stored in the computer-readable storage medium can be loaded and executed by the processor to implement the steps of the method in the above embodiments.

[0138] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes. The solutions in the embodiments of the present invention can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0139] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0140] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means embodying the function specified in the flowchart Figure 1 a flowchart or multiple flowcharts and / or block Figure 1 a block or multiple blocks.

[0141] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the function specified in the flowchart Figure 1 a flowchart or multiple flowcharts and / or block Figure 1 a block or multiple blocks.

[0142] Although the preferred embodiments of the present invention have been described, additional changes and modifications to these embodiments can be made by those skilled in the art once they learn of the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0143] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. An online monitoring method for abnormal harmonic signals of high-voltage cables, characterized in that, Comprising: Measuring harmonic signals of a high-voltage cable to be measured through a non-contact harmonic signal sensor to obtain non-contact harmonic signals; Sampling the non-contact harmonic signals, calculating based on the sampled non-contact harmonic signals, and obtaining the values of key quantization indicators; Based on the values of the key quantization indicators, determining whether the harmonic signals of the high-voltage cable are abnormal.

2. The online monitoring method according to claim 1, characterized in that The non-contact harmonic signal sensor is arranged at a preset measurement point of the high-voltage cable to be measured; The preset measurement point is set within the grounding areas at both ends of the grounding wire of the high-voltage cable to be measured, at a position 5-10 cm away from the grounding wire.

3. The online monitoring method according to claim 1, wherein Transmitting the sampled non-contact harmonic signals based on a synchronous transmission protocol of an optical fiber medium.

4. The online monitoring method according to claim 1, wherein The key quantization indicators include: Root mean square (RMS) of harmonic current, total harmonic distortion (THD), defective harmonic content, and relative harmonic content.

5. The online monitoring method according to claim 4, characterized in that The calculation formula for the value of the root mean square (RMS) of harmonic current is as follows: Wherein, I RMS is the RMS value of the harmonic current, and I1…I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

6. The online monitoring method according to claim 4, wherein The calculation formula for the value of the total harmonic distortion (THD) is as follows: Among them, THD I The value of the total harmonic distortion rate THD, I1…I n Are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

7. The online monitoring method according to claim 4, characterized in that The calculation formula for the value of the individual harmonic content is as follows: Among them, K n is the value of the defective harmonic content, and I1 and I n are the effective values of the fundamental wave and the 2nd and nth harmonics respectively.

8. The online monitoring method according to claim 4, characterized in that, The calculation formula for the value of the relative harmonic content is as follows: Among them, R n is the value of the relative harmonic content, K n is the value of the defective harmonic content, K n * is the nth harmonic content of the cable without defects.

9. An on-line monitoring system for abnormal harmonic signals of high-voltage cables, characterized in that, Comprising: A non-contact harmonic signal sensor, a collection module, a data transmission module, and a data analysis and processing module; The non-contact harmonic signal sensor is used to measure harmonic signals of a high-voltage cable to be measured to obtain non-contact harmonic signals. The collection module is used to sample the non-contact harmonic signals and transmit the sampled non-contact harmonic signals to the data analysis and processing module through the data transmission module. The data analysis and processing is used to calculate based on the sampled non-contact harmonic signals, obtain the values of key quantization indicators, and determine whether the harmonic signals of the high-voltage cable are abnormal based on the values of the key quantization indicators.

10. The online monitoring system according to claim 9, wherein, The non-contact harmonic signal sensor is arranged at a preset measurement point of the high-voltage cable to be measured; The preset measurement point is set within the grounding areas at both ends of the grounding wire of the high-voltage cable to be measured, at a position 5-10 cm away from the grounding wire.

11. The online monitoring system according to claim 9, wherein Between the collection module and the data transmission module, the sampled non-contact harmonic signals are transmitted based on a synchronous transmission protocol of an optical fiber medium.

12. The online monitoring system according to claim 9, wherein The key quantization indicators include: Root mean square (RMS) of harmonic current, total harmonic distortion (THD), defective harmonic content, and relative harmonic content.

13. The online monitoring system according to claim 12, characterized in that, The calculation formula for the value of the root mean square (RMS) of harmonic current is as follows: Wherein, I RMS is the RMS value of the harmonic current, and I1… I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

14. The online monitoring system according to claim 12, characterized in that, The calculation formula for the value of the total harmonic distortion (THD) is as follows: Among them, THD I The value of the total harmonic distortion rate THD, I1…I n are the effective values of the fundamental wave and the 2nd to nth harmonics respectively.

15. The online monitoring system according to claim 12, wherein The calculation formula for the value of the individual harmonic content is as follows: Among them, K n is the value of the defective harmonic content, and I1 and I n are the effective values of the fundamental wave and the 2nd and nth harmonics respectively.

16. The online monitoring system according to claim 12, characterized in that The calculation formula for the value of the relative harmonic content is as follows: Among them, R n is the value of the relative harmonic content, K n is the value of the defective harmonic content, K n * is the nth harmonic content of the cable without defects.

17. A computer device, characterized in that, Comprising: One or more processors; The processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method described in any one of claims 1-8 is implemented.

18. A computer-readable storage medium, characterized in that, There is a computer program stored thereon, and when the computer program is executed, the method described in any one of claims 1-8 is implemented.

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