Method and system for detecting and analyzing induced current in high voltage cable grounding loop

Abstract

The application relates to a high-voltage cable grounding loop induced current detection and analysis method and system, wherein the method comprises: live detection of three-phase metal sheaths of a high-voltage cable to obtain the grounding loop current values of the metal sheaths and the core load current values; based on the Kirchhoff voltage law and the electromagnetic induction law, a six-order linear equation set representing the electromagnetic coupling relationship among the metal sheaths is established; and the equation set is solved through the Kramer rule to obtain the linear relationship between the grounding loop current of each metal sheath and the core load current; based on the grounding loop current values and the linear relationship, it is determined whether the grounding loop of the high-voltage cable is abnormal, and the abnormal fault type is identified. Through the application, the accurate collection of the cable grounding loop current is realized, the linear relationship between the grounding loop current and the core load is solved by using the electromagnetic induction and the Kirchhoff voltage law and combining the Kramer rule, and the state of the cable grounding loop is accurately analyzed and diagnosed.

Description

Technical Field

[0001] This application relates to the field of power detection technology, and in particular to a method, system, device and medium for detecting and analyzing induced circulating current in high-voltage cable grounding circuits. Background Technology

[0002] High-voltage single-core cables are widely used in urban power grids, cross-sea power grid interconnections, and offshore wind power transmission projects. Their metal sheath / armor layer generates induced voltage due to electromagnetic induction, forming induced circulating currents in the grounded or cross-connected grounding circuits. These induced circulating currents directly affect the cable's current carrying capacity, insulation life, and operational safety. Abnormal circulating currents often correspond to typical faults such as sheath damage, multiple grounding points, incorrect cross-connection transposition, open circuits, and protector breakdown.

[0003] Currently, no effective solution has been proposed for improving the accuracy of detection and analysis of cable grounding circuits in related technologies. Summary of the Invention

[0004] This application provides a method, system, device, and medium for detecting and analyzing induced circulating current in high-voltage cable grounding circuits, in order to at least solve the problem of how to improve the accuracy of detection and analysis of cable grounding circuits in related technologies.

[0005] In a first aspect, embodiments of this application provide a method for detecting and analyzing induced circulating current in a high-voltage cable grounding circuit, the method comprising: Live testing was performed on the three-phase metal sheaths of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metal sheath. Based on Kirchhoff's voltage law and electromagnetic induction law, a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase is established. Based on the grounding circulating current value and the conductor load current value, the sixth-order linear equation system is solved by Cramer's rule to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase metal sheath; Based on the grounding circulating current value and the linear relationship, it is determined whether the grounding circuit of the high-voltage cable is abnormal, and the type of abnormal fault is identified.

[0006] In some embodiments, based on the grounding circulating current value and the linear relationship, it is determined whether the grounding loop of the high-voltage cable is abnormal, and the abnormal fault type is identified, including: Convert the grounding circulating current value into the absolute value of the grounding circulating current; The linear relationship is then converted into the ratio of circulating current to load current. The single-phase circulating current unbalance is obtained by dividing the maximum value of the grounding circulating current of each phase metal sheath by the minimum value of the grounding circulating current. Based on the absolute value of the grounding circulating current, the ratio of the circulating current to the load current, and the single-phase circulating current imbalance, the working state of the grounding circuit of the high-voltage cable is determined, wherein the working state includes normal state, warning state, and abnormal state. If the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the grounding circuit of the high-voltage cable is identified.

[0007] In some embodiments, the operating state of the grounding circuit of the high-voltage cable is determined based on the absolute value of the grounding circulating current, the ratio of circulating current to load current, and the single-phase circulating current imbalance, including: If the absolute value of the grounding circulating current is less than 50A, the ratio of the circulating current to the load current is less than 20%, and the single-phase circulating current imbalance is less than 3, then the grounding circuit of the high-voltage cable is in normal working condition. If the absolute value of the grounding circulating current is between 50A and 100A, or the ratio of the circulating current to the load current is between 20% and 50%, or the single-phase circulating current imbalance is between 3 and 5, then the working state of the grounding circuit of the high-voltage cable is a state of caution. If the absolute value of the grounding circulating current is greater than 100A, or the ratio of the circulating current to the load current is less than 50%, or the single-phase circulating current imbalance is greater than 5, then the grounding circuit of the high-voltage cable is in an abnormal state.

[0008] In some embodiments, when the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the high-voltage cable grounding circuit is identified as follows: Discrete Fourier transform is performed on the grounding circulating current value and the conductor load current value to obtain the power frequency complex number representation, and the three-phase phase difference of the high-voltage cable is calculated using the complex number quotient method; The grounding circulating current is separated into components using a double π model to obtain the induced current component and the leakage current component. If the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the grounding circuit of the high-voltage cable can be accurately identified based on the grounding circulating current value, three-phase phase difference, induced current component and leakage current component.

[0009] In some embodiments, the method includes: The obtained grounding circulating current value, conductor load current value, linear relationship, three-phase phase difference, induced current component, leakage current component, as well as the working status judgment result and abnormal fault type identification result are uploaded to the monitoring platform to generate historical trend curves for abnormal early warning and degradation prediction.

[0010] In some embodiments, live-line testing is performed on the three-phase metallic sheaths of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metallic sheath, including: Live testing is performed on the three-phase metal sheath of the high-voltage cable to obtain the current acquisition signal of each phase metal sheath, wherein the current acquisition signal includes the grounding circulating current signal and the conductor composite current signal; The grounding circulating current signal and the conductor composite current signal are digitized to obtain the grounding circulating current value and the conductor load current value.

[0011] In some embodiments, digitizing the grounding circulating current signal and the conductor composite current signal to obtain the grounding circulating current value and the conductor load current value includes: The grounding circulating current signal is digitized to obtain the grounding circulating current value; The synthesized current signal of the conductor is digitized and subjected to circulating current interference cancellation processing and AC positive and negative cancellation processing to obtain the conductor load current value.

[0012] Secondly, embodiments of this application provide a high-voltage cable grounding loop induced circulating current detection and analysis system, the system being used to perform the method described in the first aspect above, the system including a detection module, an analysis module and a diagnostic module; The detection module is used to perform live detection on the three-phase metal sheath of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metal sheath. The analysis module is used to establish a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase, based on Kirchhoff's voltage law and electromagnetic induction law. The analysis module is used to solve the sixth-order linear equation system using Cramer's rule based on the grounding circulating current value and the conductor load current value, so as to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase metal sheath. The diagnostic module is used to determine whether the grounding circuit of the high-voltage cable is abnormal based on the grounding circulating current value and the linear relationship, and to identify the type of abnormal fault.

[0013] Thirdly, embodiments of this application provide an analysis and diagnosis device for a high-voltage cable grounding circuit, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method described in the first aspect above.

[0014] Fourthly, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect above.

[0015] Compared to related technologies, this application provides a method, system, device, and medium for detecting and analyzing induced circulating current in a high-voltage cable grounding loop. The method involves performing live detection on the three-phase metal sheaths of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase's metal sheath. Based on Kirchhoff's voltage law and the law of electromagnetic induction, a sixth-order linear equation system characterizing the electromagnetic coupling relationship between the phase metal sheaths is established. Based on the grounding circulating current value and the core load current value, the sixth-order linear equation system is solved using Cramer's rule to obtain the linear relationship between the grounding circulating current of each phase's metal sheath and the core load current. Based on the grounding circulating current value and the linear relationship, it determines whether the grounding loop of the high-voltage cable is abnormal and identifies the type of abnormal fault. This achieves accurate acquisition of the cable grounding circulating current. By utilizing electromagnetic induction and Kirchhoff's voltage law, combined with Cramer's rule, the linear relationship between the grounding circulating current and the core load is solved to accurately analyze and diagnose the state of the cable grounding loop, thus solving the problem of how to improve the accuracy of cable grounding loop detection and analysis. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of the steps of the high-voltage cable grounding circuit induced circulating current detection and analysis method according to an embodiment of this application; Figure 2 This is a schematic diagram of the internal structure of the analysis and diagnostic device according to an embodiment of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0018] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0019] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0020] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “a,” “an,” “an,” “the,” and similar words used in this application do not indicate quantity limitation and may indicate singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms “connected,” “linked,” “coupled,” and similar words used in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following objects are in an "or" relationship. The terms "first," "second," and "third" used in this application are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0021] This application provides a method for detecting and analyzing induced circulating current in a high-voltage cable grounding circuit. Figure 1 This is a flowchart illustrating the steps of the high-voltage cable grounding circuit induced circulating current detection and analysis method according to an embodiment of this application, as follows: Figure 1 As shown, the method includes the following steps: Step S102: Perform live testing on the three-phase metal sheath of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metal sheath. Step S102 specifically includes the following steps: Step S1021: Perform live detection on the three-phase metal sheath of the high-voltage cable to obtain the current acquisition signal of each phase metal sheath, wherein the current acquisition signal includes the grounding circulating current signal and the conductor composite current signal. It should be noted that, for step S1021, a grounding current detection instrument is used for live-line testing, simultaneously acquiring the grounding circulating current signal and the composite current signal of the conductor core. This simultaneous acquisition meets the requirements of being in phase, having the same frequency, and the same sampling rate. The core component of the grounding current detection instrument is a double Rogowski coil with consistent linearity, and the instrument should be able to measure grounding wires with a diameter of not less than 50 mm, have a maximum current range of not less than 500 A, an AC current measurement resolution of 0.2 A, and should have multiple AC current ranges. Furthermore, the testing cycle for grounding current detection of the cable's metallic sheath should be performed according to Table 1.

[0022] Table 1

[0023] Step S1022: The grounding circulating current signal is digitized to obtain the grounding circulating current value; Step S1023: The composite current signal of the conductor is digitized and subjected to circulating current interference cancellation processing and AC positive and negative cancellation processing to obtain the conductor load current value.

[0024] It should be noted that, for step S1023, the composite current signal of the conductor is the load current plus the circulating current. Therefore, the composite current signal of the conductor is first converted into a digital sample value, and the in-phase sample points are subtracted point by point to cancel the circulating current interference. ADC total - ADC g = (I run +I n )*K- I n K = I run *K Among them, ADC tota For synthesizing the current signal of the wire core, ADC g For grounding circulating current signal, I run I represents the conductor load current value. n Where K is the grounding circulating current value, and K is the coil proportionality coefficient; Then for ADC total - ADC gThe absolute values ​​of the difference signals are taken and summed to eliminate AC positive and negative cancellation; the full-range nonlinear error is compensated by a piecewise calibration curve and linear interpolation to obtain the core load current value I. run .

[0025] Step S104: Based on Kirchhoff's voltage law and electromagnetic induction law, establish a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase. Specifically, in step S104, based on Kirchhoff's voltage law and electromagnetic induction law, a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase is established:

[0026] Among them, R d R is the DC resistance of a single grounding lead. e The equivalent current dissipation resistance of the ground, R is the phasor sum of the three-phase circuit currents flowing to ground; s +jX s I is the power frequency complex impedance of the cable core conductor. sa I sb I sc These are the load current phasors for the three phase conductors A, B, and C, respectively; U' sa 、U' sb 、U' sc U'' is the main magnetic coupling induced voltage component of the conductor current on the sheath. sa 、U'' sb 、U'' sc U represents the cross-magnetic coupling induced voltage component of the current in the other two phase conductors on the sheath of this phase. sa U sb U sc R is the applied phase voltage at the beginning of the three-phase conductor; k +jX k I is the power frequency complex impedance of the metal-sheathed (or armored) circuit. ka I kb I kc These are the grounding circulating current phasors of the three-phase metal sheaths A, B, and C, respectively; U' ka 、U' kb 、U' kc U'' is the direct magnetic coupling induced voltage component of the current in the main phase conductor received by the sheathing circuit. ka 、U'' kb 、U'' kc U is the cross-magnetic coupling induced voltage component of the currents of the other two phase conductors received by the sheath circuit of this phase. ka U kb U kcThis is the equivalent external voltage applied at the beginning of the sheath circuit.

[0027] Step S106: Based on the grounding circulating current value and the conductor load current value, solve the sixth-order linear equation system using Cramer's rule to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase metal sheath. Specifically, in step S106, based on the grounding circulating current value and the conductor load current value, the sixth-order linear equation system is solved using Cramer's rule to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase's metal sheath:

[0028] Among them, I k This is the phasor of the grounding circulating current of the corresponding phase metal sheath of the high-voltage cable; The coefficient matrix of the aforementioned sixth-order linear equation system is composed of the grounding lead resistance, the equivalent earth resistance, the conductor impedance, the metal sheath impedance, and the phase-to-phase electromagnetic coupling related parameters. is the determinant value of the sixth-order linear equation system (and the denominator term for solving using Cramer's rule); To make the coefficient matrix The sheath circulation I is pending ka (Similarly, kb and kc correspond to the circulating currents of the sheaths in phases B and C, respectively.) The columns corresponding to these terms are replaced with the voltage constant terms on the right side of the equation system to obtain the replacement matrix. is the determinant value of the replacement matrix (the numerator term solved by Cramer's rule); I is the measured load current phasor of the cable core.

[0029] Step S108: Based on the grounding loop current value and linear relationship, determine whether the grounding loop of the high-voltage cable is abnormal and identify the abnormal fault type.

[0030] Step S108 specifically includes the following steps: Step S1081: Convert the grounding circulating current value into the absolute value of the grounding circulating current; Step S1082: Convert the linear relationship into the ratio of circulating current to load current; Step S1083: Divide the maximum value of the grounding circulating current of each phase metal sheath by the minimum value of the grounding circulating current to obtain the single-phase circulating current unbalance. Step S1084: Based on the absolute value of the grounding circulating current, the ratio of the circulating current to the load current, and the unbalance of the single-phase circulating current, determine the working state of the grounding circuit of the high-voltage cable. The working state includes normal state, warning state, and abnormal state. Specifically, step S1084 involves determining the operating status of the grounding loop of the high-voltage cable based on the absolute value of the grounding circulating current, the ratio of the circulating current to the load current, and the single-phase circulating current imbalance. (1) If the absolute value of the grounding current is less than 50A, the ratio of the circulating current to the load current is less than 20%, and the single-phase circulating current imbalance is less than 3, then the working state of the grounding circuit of the high-voltage cable is normal. (2) If the absolute value of the grounding current is 50A to 100A, or the ratio of the circulating current to the load current is 20% to 50%, or the unbalance of the single-phase circulating current is 3 to 5, then the working state of the grounding circuit of the high-voltage cable is a state of caution. (3) If the absolute value of the grounding current is greater than 100A, or the ratio of the circulating current to the load current is less than 50%, or the single-phase circulating current imbalance is greater than 5, then the working state of the grounding circuit of the high-voltage cable is abnormal.

[0031] It should be noted that the diagnostic criteria for grounding current detection of the metallic sheath of high-voltage cable lines can be further detailed in Table 2.

[0032] Table 2

[0033] Step S1085: If the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the grounding circuit of the high-voltage cable is identified.

[0034] Step S1085 specifically includes the following steps: S1. Perform discrete Fourier transform on the grounding circulating current value and the conductor load current value to obtain the power frequency complex number representation, and use the complex number quotient method to calculate the three-phase phase difference of the high-voltage cable; It should be noted that the phase difference calculated using the complex quotient method after the discrete Fourier transform of S1 can be expressed as:

[0035] Where j is the imaginary unit; I1 and Q1 are the real and imaginary parts of the phasor obtained by the Discrete Fourier Transform of the first measured signal (grounding loop current), respectively; I2 and Q2 are the real and imaginary parts of the phasor obtained by the Discrete Fourier Transform of the second reference signal (core load current), respectively; the right side of the equation is the expansion form of the denominator of the complex division on the left side after realization. The real part can be used to calculate the amplitude ratio of the two signals, and the imaginary part can be used to further solve for the phase difference between the two signals.

[0036] S2. The grounding circulating current is separated into components using a double π model to obtain the induced current component and the leakage current component. It should be noted that the component separation of the double π model in S2 can be expressed as:

[0037] Among them, I cai The phasor of the capacitive induced current generated in the i-th segment of phase A of the cable (the capacitive circulating current component generated by the main insulation capacitance effect of the cable); j is the imaginary unit; ω is the angular frequency of the power frequency AC system; C ai U is the equivalent capacitance to ground of the i-th segment of phase A of the cable; A This refers to the phase voltage phasor of phase A of the cable.

[0038] S3. When the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the high-voltage cable grounding circuit is accurately identified based on the grounding circulating current value, three-phase phase difference, induced current component and leakage current component.

[0039] For example, regarding the identification of abnormal fault types in S3, if the circulating current increases significantly, it can be identified as multiple grounding / sheath damage / cross-connection transposition error; if the circulating current of a certain phase is close to 0, it can be identified as sheath open circuit; if the three phases are asymmetrical, it can be identified as cross-connection wiring error (accurate judgment based on the three phase difference); if the circulating current still exceeds the standard under light load, it can be identified as leakage current dominance / outer sheath aging (accurate judgment based on the leakage current component).

[0040] After step S108, the method further includes step S109, which involves uploading the obtained grounding circulating current value, conductor load current value, linear relationship, three-phase phase difference, induced current component, leakage current component, as well as the working status determination result and abnormal fault type identification result to the monitoring platform to generate historical trend curves for abnormal early warning and degradation prediction.

[0041] The methods and steps provided in this application achieve accurate acquisition of cable grounding loop current. Utilizing electromagnetic induction and Kirchhoff's voltage law, combined with Cramer's law, the linear relationship between the grounding loop current and the conductor load is solved, enabling precise analysis and diagnosis of the cable grounding loop status. This solves the problem of how to improve the accuracy of cable grounding loop detection and analysis. Specifically: 1) Using the consistency of dual Rogowski coils, digital domain cancellation of the loop current component is achieved, extracting the pure load current; 2) Based on electromagnetic induction and Cramer's law, an accurate mathematical model (sixth-order linear equations) is established to solve the load current-grounding loop current problem; 3) High-precision phase measurement is achieved using DFT and the complex quotient method to complete vector analysis; 4) The induced component and leakage component are separated using a double π model, improving diagnostic reliability.

[0042] It should be noted that the steps shown in the above process or in the flowchart of the accompanying figures can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0043] This application provides a high-voltage cable grounding loop induced circulating current detection and analysis system. The system is used to perform the method of the first aspect described above. The system includes a detection module, an analysis module, and a diagnostic module. The detection module is used to perform live detection on the three-phase metal sheath of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metal sheath. The analysis module is used to establish a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase, based on Kirchhoff's voltage law and electromagnetic induction law. The analysis module is used to solve a set of sixth-order linear equations based on the grounding circulating current value and the conductor load current value using Cramer's rule, so as to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase metal sheath. The diagnostic module is used to determine whether the grounding loop of the high-voltage cable is abnormal based on the grounding circulating current value and linear relationship, and to identify the type of abnormal fault.

[0044] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0045] This application provides an analysis and diagnosis device for high-voltage cable grounding circuits, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method described in the first aspect above.

[0046] Preferably, a set of on-site testing cases based on the analysis and diagnostic device is provided, specifically: The on-site inspection was conducted by the work team using a clamp multimeter in conjunction with the analysis and diagnostic device for the high-voltage cable grounding circuit. The measured data are shown in the table below. Table 3 shows the grounding current, Table 4 shows the grounding / load current and phase, and Table 5 shows the phase-to-phase ratio of the grounding current.

[0047] Table 3

[0048] Table 4

[0049] Note: The analysis and diagnosis device for the high-voltage cable grounding circuit supports the identification of three different phases. The pilot site only tested single-phase identification.

[0050] Table 5

[0051] The pilot evaluation verified that the intelligent analysis and diagnosis device for live detection of high-voltage cable grounding systems performed outstandingly compared with traditional clamp meters. Based on circulating current detection, it is the first to integrate the synchronous acquisition of multi-dimensional parameters such as "measured current, grounding / load current, phase, and phase-to-phase ratio", and all tests can be completed with a single wiring connection.

[0052] Optionally, the above-mentioned analysis and diagnostic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0053] Optionally, the analysis and diagnostic device may further include a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for detecting and analyzing induced circulating currents in high-voltage cable grounding loops. The display screen may be an LCD screen or an e-ink screen. The input devices may be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the device's casing, or an external keyboard, touchpad, or mouse.

[0054] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated here.

[0055] Furthermore, in conjunction with the high-voltage cable grounding loop induced current detection and analysis method in the above embodiments, this application embodiment can provide a storage medium for implementation. This storage medium stores a computer program; when executed by a processor, the computer program implements any of the high-voltage cable grounding loop induced current detection and analysis methods in the above embodiments.

[0056] In one embodiment, Figure 2 This is a schematic diagram of the internal structure of the analysis and diagnostic device according to an embodiment of this application, such as... Figure 2 As shown, an analysis and diagnostic device is provided. This device can be a server, and its internal structure diagram can be as follows. Figure 2As shown. This analytical diagnostic device includes a processor, a network interface, internal memory, and non-volatile memory connected via an internal bus. The non-volatile memory stores the operating system, computer programs, and a database. The processor provides computing and control capabilities, the network interface communicates with external terminals via a network, the internal memory provides the environment for the operating system and computer programs to run, and the computer programs, when executed by the processor, implement a method for detecting and analyzing induced circulating currents in high-voltage cable grounding loops. The database stores data.

[0057] Those skilled in the art will understand that Figure 2 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the analytical diagnostic device to which the present application is applied. A specific analytical diagnostic device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0058] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0059] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been 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 specification.

[0060] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for detecting and analyzing induced circulating current in a high-voltage cable grounding circuit, characterized in that, The method includes: Live testing was performed on the three-phase metal sheaths of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metal sheath. Based on Kirchhoff's voltage law and electromagnetic induction law, a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase is established. Based on the grounding circulating current value and the conductor load current value, the sixth-order linear equation system is solved by Cramer's rule to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase metal sheath; Based on the grounding circulating current value and the linear relationship, it is determined whether the grounding circuit of the high-voltage cable is abnormal, and the type of abnormal fault is identified.

2. The method according to claim 1, characterized in that, Based on the grounding circulating current value and the linear relationship, it is determined whether the grounding loop of the high-voltage cable is abnormal, and the abnormal fault types are identified as follows: Convert the grounding circulating current value into the absolute value of the grounding circulating current; The linear relationship is then converted into the ratio of circulating current to load current. The single-phase circulating current unbalance is obtained by dividing the maximum value of the grounding circulating current of each phase metal sheath by the minimum value of the grounding circulating current. Based on the absolute value of the grounding circulating current, the ratio of the circulating current to the load current, and the single-phase circulating current imbalance, the working state of the grounding circuit of the high-voltage cable is determined, wherein the working state includes normal state, warning state, and abnormal state. If the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the grounding circuit of the high-voltage cable is identified.

3. The method according to claim 2, characterized in that, Based on the absolute value of the grounding circulating current, the ratio of circulating current to load current, and the single-phase circulating current imbalance, the operating state of the grounding circuit of the high-voltage cable is determined as follows: If the absolute value of the grounding circulating current is less than 50A, the ratio of the circulating current to the load current is less than 20%, and the single-phase circulating current imbalance is less than 3, then the grounding circuit of the high-voltage cable is in normal working condition. If the absolute value of the grounding circulating current is between 50A and 100A, or the ratio of the circulating current to the load current is between 20% and 50%, or the single-phase circulating current imbalance is between 3 and 5, then the working state of the grounding circuit of the high-voltage cable is a state of caution. If the absolute value of the grounding circulating current is greater than 100A, or the ratio of the circulating current to the load current is less than 50%, or the single-phase circulating current imbalance is greater than 5, then the grounding circuit of the high-voltage cable is in an abnormal state.

4. The method according to claim 2, characterized in that, When the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault types of the high-voltage cable grounding circuit identified include: Discrete Fourier transform is performed on the grounding circulating current value and the conductor load current value to obtain the power frequency complex number representation, and the three-phase phase difference of the high-voltage cable is calculated using the complex number quotient method; The grounding circulating current is separated into components using a double π model to obtain the induced current component and the leakage current component. If the grounding circuit of the high-voltage cable is determined to be in an abnormal state, the abnormal fault type of the grounding circuit of the high-voltage cable can be accurately identified based on the grounding circulating current value, three-phase phase difference, induced current component and leakage current component.

5. The method according to claim 4, characterized in that, The method includes: The obtained grounding circulating current value, conductor load current value, linear relationship, three-phase phase difference, induced current component, leakage current component, as well as the working status judgment result and abnormal fault type identification result are uploaded to the monitoring platform to generate historical trend curves for abnormal early warning and degradation prediction.

6. The method according to claim 1, characterized in that, Live-line testing of the three-phase metallic sheaths of high-voltage cables yields the grounding circulating current values ​​and core load current values ​​for each phase's metallic sheath, including: Live testing is performed on the three-phase metal sheath of the high-voltage cable to obtain the current acquisition signal of each phase metal sheath, wherein the current acquisition signal includes the grounding circulating current signal and the conductor composite current signal; The grounding circulating current signal and the conductor composite current signal are digitized to obtain the grounding circulating current value and the conductor load current value.

7. The method according to claim 6, characterized in that, The grounding circulating current signal and the conductor composite current signal are digitized to obtain the grounding circulating current value and the conductor load current value, including: The grounding circulating current signal is digitized to obtain the grounding circulating current value; The synthesized current signal of the conductor is digitized and subjected to circulating current interference cancellation processing and AC positive and negative cancellation processing to obtain the conductor load current value.

8. A high-voltage cable grounding circuit induced circulating current detection and analysis system, characterized in that, The system is used to perform the method according to any one of claims 1 to 7, and the system includes a detection module, an analysis module, and a diagnostic module; The detection module is used to perform live detection on the three-phase metal sheath of the high-voltage cable to obtain the grounding circulating current value and core load current value of each phase metal sheath. The analysis module is used to establish a set of sixth-order linear equations characterizing the electromagnetic coupling relationship between the metal sheaths of each phase, based on Kirchhoff's voltage law and electromagnetic induction law. The analysis module is used to solve the sixth-order linear equation system using Cramer's rule based on the grounding circulating current value and the conductor load current value, so as to obtain the linear relationship between the grounding circulating current and the conductor load current of each phase metal sheath. The diagnostic module is used to determine whether the grounding circuit of the high-voltage cable is abnormal based on the grounding circulating current value and the linear relationship, and to identify the type of abnormal fault.

9. A device for analyzing and diagnosing high-voltage cable grounding circuits, comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the method of any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1 to 7.

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