A cable joint resonance real-time diagnosis method, device and medium

Abstract

The present application relates to a kind of cable joint resonance real-time diagnosis method, equipment and medium, belong to power equipment condition monitoring technical field, wherein method includes the following steps: obtaining high-frequency current signal that high-frequency current sensor gathers and ultrasonic sensor array gathers ultrasonic vibration signal;High-frequency current signal and ultrasonic vibration signal are carried out signal synchronization, and high-frequency current characteristic and ultrasonic array characteristic are extracted;Based on high-frequency current characteristic and ultrasonic array characteristic, main frequency synchronism index, normalization phase stability index and nonlinear coupling index are calculated, and weighted summation is determined fusion confidence function;Based on fusion confidence function, judge whether there is resonance, if there is, then carry out resonance source positioning.Compared with prior art, the present application has the advantages of high precision, low false alarm, strong adaptation, is suitable for new energy grid-connected, urban smart grid, wind power and other key power system scenarios.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring technology, and in particular to a method, equipment and medium for real-time diagnosis of cable joint resonance. Background Technology

[0002] With the high proportion of new energy grid connection and the continuous increase in urban power grid load density, the operational reliability of high-voltage cable joints has become a core factor affecting power system safety. Especially in scenarios with fluctuating output from photovoltaic and wind power, the resonance failure rate of cable joints has seen explosive growth. Industry statistics show that the proportion of resonance failures in 66kV and above cables has surged from 12% five years ago to 27% currently. Such failures not only lead to frequent unplanned power outages but can also trigger cascading accidents such as insulation breakdown. High-reliability scenarios such as offshore wind power transmission projects and urban integrated utility tunnels urgently require real-time resonance early warning. However, traditional detection methods have fundamental limitations, resulting in significant direct economic losses annually due to misjudgments and missing location information, severely hindering the construction of new power systems.

[0003] Currently, cable joint condition monitoring mainly relies on three technical approaches. The electrical parameter method based on high-frequency current (such as Chinese patent CN1134667A) achieves resonance detection by analyzing harmonics in the 1-30MHz frequency band, but background harmonic interference from the power grid causes a false alarm rate exceeding 25%. The mechanical vibration method based on ultrasonic sensors (such as Chinese patent CN11248565A) can capture insulation layer vibration signals, but it is difficult to distinguish between electromagnetic resonant vibration and environmental mechanical noise. The system-level impedance analysis method (such as Chinese patent CN114994478A) can diagnose power grid resonance, but its spatial resolution is greater than 10 meters, making it unable to locate internal fault points within the joint.

[0004] The aforementioned technologies face three core challenges. At the mechanistic level, traditional methods neglect the electromagnetic-mechanical energy coupling effect during resonance and lack quantitative modeling of the correlation between temperature deformation and resonant frequency. At the implementation level, single-sensor solutions have significant detection blind spots, with frequency-division resonance exhibiting a false alarm rate as high as 100%, and software-level time synchronization errors exceeding 100 microseconds causing phase analysis failure. At the functional level, existing technologies cannot achieve fault location, forcing maintenance personnel to replace high-value connectors entirely, increasing maintenance costs by over 300%. These shortcomings leave power systems struggling to cope with the new resonance risks brought about by the integration of new energy sources into the grid.

[0005] Therefore, a method capable of accurately detecting resonance is currently needed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art, such as high false alarm rate, slow response, and difficulty in positioning, and to provide a method, device and medium for real-time diagnosis of cable joint resonance.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] According to a first aspect of the present invention, a method for real-time diagnosis of cable joint resonance is provided, the method comprising the following steps:

[0009] Acquire high-frequency current signals from a high-frequency current sensor and ultrasonic vibration signals from an ultrasonic sensor array;

[0010] The high-frequency current signal and the ultrasonic vibration signal are synchronized, and the high-frequency current features and ultrasonic array features are extracted.

[0011] Based on the high-frequency current characteristics and ultrasonic array characteristics, the main frequency synchronization index, normalized phase stability index, and nonlinear coupling index are calculated, and the weighted summation of the indices is used to determine the fusion confidence function.

[0012] The existence of resonance is determined based on the fusion confidence function. If resonance exists, the source of resonance is located.

[0013] The extraction of the high-frequency current features specifically involves performing a Fourier transform on the high-frequency current signal I(t) to extract the dominant frequency position.

[0014] ,

[0015] in, Indicates Fourier transform, This means searching across all possible frequencies f to maximize the objective function. This refers to the dominant frequency position of the high-frequency current signal, i.e., the extracted high-frequency current characteristics;

[0016] The extraction of ultrasonic array features specifically involves: weighted superposition of ultrasonic vibration signals collected by multiple ultrasonic sensors in the ultrasonic sensor array to obtain a synthesized array vibration signal.

[0017] ,

[0018] in, Let N be the ultrasonic vibration signal acquired by the i-th ultrasonic sensor, and N be the number of ultrasonic sensors. To synthesize vibration signals for arrays;

[0019] Synthetic vibration signals from array Perform a Fourier transform to extract the dominant frequency position:

[0020] ,

[0021] in, The dominant frequency position of the array-synthesized vibration signal is the extracted ultrasonic array feature.

[0022] The calculation method for the main frequency synchronization index is as follows:

[0023] ,

[0024] in, It is characterized by high-frequency current. Features of ultrasound arrays To set the tolerance difference, It is a key indicator of frequency synchronization.

[0025] The normalized phase stability index is calculated as follows:

[0026] If the difference between the main peak frequencies of the high-frequency current signal and the array-synthesized vibration signal obtained by superimposing the ultrasonic vibration signal is within a set tolerance range... Within the range, the resonant dominant frequency is defined as:

[0027] ,

[0028] in, It is characterized by high-frequency current. Features of ultrasound arrays This is the resonant main frequency point;

[0029] The high-frequency current signal and the array-synthesized vibration signal are respectively analyzed with a center frequency of... bandwidth is Narrowband filtering is used to extract the main frequency carrier:

[0030] ,

[0031] in, Indicates a high-frequency current signal. This indicates the array synthesized vibration signal. The center frequency is Bandwidth is Narrowband filter, This represents the main frequency carrier of a high-frequency current signal. This represents the main frequency carrier of the array-synthesized vibration signal;

[0032] Perform Hilbert transform on the main frequency carrier of the high-frequency current signal and the array-synthesized vibration signal to extract the instantaneous phase:

[0033] ,

[0034] ,

[0035] in, Represents the Hilbert transform. This represents the analytic signal of the high-frequency current after the Hilbert transform. This represents the analytic signal of ultrasound after Hilbert transform, where j is the imaginary unit. This indicates the calculation of the phase angle of a complex number. Represents the instantaneous phase of a high-frequency current signal. Indicates the instantaneous phase of the ultrasound signal;

[0036] Constructing phase difference:

[0037] ,

[0038] If the phase difference The standard deviation within the preset duration is lower than This indicates the presence of phase-locked loop. Calculate the normalized phase stability index:

[0039] ,

[0040] in, , representing the normalized phase stability index, It represents the standard deviation.

[0041] The calculation method for the nonlinear coupling index is as follows:

[0042] Perform a Fourier transform on the high-frequency current signal I(t) to identify significant spectral peaks other than its dominant frequency and its integer harmonics. Two of the peak frequencies are set as Calculate the intermodulation frequency and the combination frequency:

[0043] , ,

[0044] ,

[0045] in, ,and ; Indicates the intermodulation frequency. Indicates the combination frequency;

[0046] A nonlinear candidate frequency set for high-frequency current signals is constructed based on the calculated intermodulation frequencies and combination frequencies. ;

[0047] Synthetic vibration signals from array Perform Fourier transform to extract subharmonic components and fractional harmonics:

[0048] ,

[0049] ,

[0050] in, , Indicates array-synthesized vibration signal main frequency; Indicates the subharmonic component. Indicates fractional frequency;

[0051] A set of nonlinear candidate frequencies for ultrasonic vibration signals is constructed based on the calculated subharmonic components and fractional harmonics. ;

[0052] Construct the intersection of the nonlinear candidate frequency sets of the high-frequency current signal and the ultrasonic vibration signal: This refers to the nonlinear frequency term that appears simultaneously in both modes;

[0053] The nonlinear coupling index is calculated based on the intersection:

[0054] ,

[0055] in, It is a nonlinear coupling index.

[0056] The calculation method for the fusion confidence function is as follows:

[0057] ,

[0058] in, To fuse the confidence function, As a primary frequency synchronization indicator, This is a normalized phase stability index. It is a nonlinear coupling index. It is an adaptive weight that takes into account factors such as ambient temperature, cable structure, and operating conditions. The initial weights corresponding to each factor are determined by a preset mapping rule and then normalized. Specifically, the initial weight corresponding to the ambient temperature is determined based on the difference between the current temperature and the reference temperature; the initial weight corresponding to the cable structure is determined based on the shielding complexity, joint type, and insulation process used; and the initial weight corresponding to the operating conditions is determined based on the magnitude of the load current.

[0059] The method for locating the resonant source is as follows:

[0060] Let the propagation speed of a high-frequency current signal be . The propagation speed of ultrasonic vibration signals in the cable insulation medium is Let the vibration source point be... The position of the i-th ultrasonic array sensor is Calculate the propagation time of the ultrasonic signal:

[0061] ,

[0062] in, Let be the propagation time of the i-th ultrasonic array sensor;

[0063] electromagnetic signal propagation time of high-frequency current ;

[0064] The time difference between the arrival of the high-frequency current electromagnetic signal and the ultrasonic signal from the i-th ultrasonic array sensor is: The calculation formula is as follows:

[0065] ,

[0066] By minimizing the squared residual between the theoretical propagation time and the actual time difference, a nonlinear least squares positioning model is constructed, and a nonlinear least squares optimization problem is established:

[0067] ,

[0068] Solve the nonlinear least squares optimization problem to obtain the three-dimensional spatial coordinates. This enables the localization of the resonant source.

[0069] The method for calculating the propagation speed of the ultrasonic vibration signal in the cable insulation medium is as follows:

[0070] ,

[0071] in, It is the reference speed of sound. It is the temperature coefficient of sound speed. It is the temperature change relative to a reference.

[0072] According to a second aspect of the present invention, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the program to implement the method described thereon.

[0073] According to a third aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the method described thereon.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] (1) The present invention firstly acquires electromagnetic and vibration response signals inside the cable synchronously through a high-sensitivity current sensor and a ring ultrasonic array, and performs microsecond-level time alignment. Then, it extracts key features from the two modes and constructs a multi-dimensional fusion criterion based on frequency synchronization, phase consistency and nonlinear coupling. By fusing multiple feature indicators through a dynamic weight model, it accurately determines whether resonance occurs. It also constructs a time difference equation system based on the propagation speed difference of the two modes to achieve centimeter-level three-dimensional positioning, thereby improving the resonance positioning accuracy and real-time diagnostic performance.

[0076] (2) This invention is the first to fuse and analyze high-frequency current signals and ultrasonic vibration signals in a synchronous manner, breaking through the limitations of traditional electrical single-mode detection. It achieves mutual verification of resonance events through the physical coupling relationship between electromagnetic and acoustic signals, greatly reducing the false alarm rate and enhancing the ability to identify complex fault types.

[0077] (3) This invention proposes a fusion criterion based on multiple independent physical characteristics such as frequency alignment, phase consistency, and nonlinear intermodulation coupling, and introduces adaptive dynamic weights to comprehensively evaluate the confidence of the resonance state, thereby achieving a more robust and accurate judgment logic with good environmental adaptability and generalizability.

[0078] (4) This invention utilizes the difference in propagation speed between electromagnetic waves and sound waves in different media, combined with an array-type ultrasonic direction finding mechanism, to perform high-precision time difference positioning, which can realize centimeter-level spatial inversion of resonant sources, significantly improving the resolution and reliability of fault location. Attached Figure Description

[0079] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0080] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0081] 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.

[0082] Example 1

[0083] This embodiment provides a real-time diagnostic method for cable joint resonance, aiming to solve key industry problems such as high false alarm rate, lack of localization capability, and slow response speed in traditional detection technologies. The method first acquires high-frequency current spectrum signals of the cable joint conductor layer in real time using an embedded high-sensitivity current sensor. Simultaneously, it utilizes a ring-shaped distributed multi-channel ultrasonic array to accurately monitor the mechanical vibration signals on the insulation layer surface. An advanced time synchronization architecture based on satellite time synchronization and hardware-level processing is employed to achieve microsecond-level precise time alignment of the dual-mode signals. Subsequently, deep collaborative feature extraction is performed on the acquired signals: on the current side, the dynamic variation characteristics of harmonic amplitude and nonlinear intermodulation distortion are comprehensively analyzed; on the vibration side, the temperature-compensated acoustic wave propagation velocity shift characteristics, fundamental frequency vibration energy distribution, and subharmonic resonance characteristics are extracted. Furthermore, a multi-channel ultrasonic array is constructed... The three-dimensional physics fusion criterion—by rigorously verifying the fundamental frequency synchronization characteristics of electromagnetic signals and mechanical vibration signals, the directional consistency of electromagnetic dispersion effects and acoustic propagation paths, and the corroborating relationship between nonlinear distortion characteristics and mechanical subharmonics, an adaptive dynamic weighting calculation model is employed to comprehensively evaluate the confidence level of resonance occurrence. When the confidence level reaches a preset threshold, a high-precision time difference equation set is established by accurately calculating the significant difference in propagation speeds of electromagnetic waves and sound waves in the medium. This equation set is then solved using an optimized advanced mathematical algorithm to achieve precise three-dimensional spatial positioning of the resonance source. Simultaneously, an early warning mechanism is implemented based on the early change trends of nonlinear characteristics. This method possesses advantages such as high accuracy, low false alarm rate, and strong adaptability, making it suitable for key power system scenarios such as new energy grid integration, smart grids in cities, and wind power, and has broad engineering application prospects.

[0084] Specifically, such as Figure 1 As shown, the method includes the following steps:

[0085] Step 1) Obtain the high-frequency current signal collected by the high-frequency current sensor and the ultrasonic vibration signal collected by the ultrasonic sensor array.

[0086] First, a single high-sensitivity, high-frequency current transformer is deployed near the joint conductor to collect the high-frequency components of the current signal inside the cable in real time. Its typical sampling frequency is above 100 MHz, covering the resonant characteristic frequency band from 3 MHz to 100 MHz.

[0087] Secondly, several ultrasonic sensors are circumferentially arranged on the outer surface of the joint insulation to form a ring array structure, typically 4 to 16 sensors. The sensors can be piezoelectric accelerometers, possessing high sensitivity and wide bandwidth response capabilities. The vibration signals acquired by the ultrasonic array are multi-channel time series, reflecting the multi-point resonant response characteristics of the structure.

[0088] Step 2) Synchronize the high-frequency current signal and the ultrasonic vibration signal, and extract the high-frequency current features and ultrasonic array features.

[0089] Step 21) Signal Synchronization

[0090] This embodiment solves the cross-modal signal alignment problem based on a GPS-PPS+FPGA hardware synchronization architecture:

[0091] 1) Clock reference: The GPS receiver outputs a 1PPS (pulse per second) signal with a time accuracy of ±100ns;

[0092] 2) Timestamp generation: The FPGA triggers on the rising edge of the pulse to add a 64-bit nanosecond-level timestamp to the dual-channel ADC sampling data;

[0093] 3) Delay compensation: Calculate transmission delay by calibrating the cable.

[0094] ,

[0095] in, For cable length, For signal propagation speed, , It is the speed of light in a vacuum. This refers to transmission delay.

[0096] The signal is calibrated based on the calculated transmission delay.

[0097] Step 22) High-frequency current feature extraction

[0098] Perform a Fourier transform on the high-frequency current signal I(t) to extract the dominant frequency position:

[0099] ,

[0100] in, Indicates Fourier transform, This means searching across all possible frequencies f to maximize the objective function. This represents the dominant frequency position of the high-frequency current signal, i.e., the extracted high-frequency current characteristics.

[0101] Step 23) Ultrasonic array feature extraction

[0102] The ultrasonic vibration signals collected by multiple ultrasonic sensors in the ultrasonic sensor array are weighted and superimposed to obtain the array-synthesized vibration signal:

[0103] ,

[0104] in, Let N be the ultrasonic vibration signal acquired by the i-th ultrasonic sensor, and N be the number of ultrasonic sensors. To synthesize vibration signals for arrays;

[0105] Synthetic vibration signals from array Perform a Fourier transform to extract the dominant frequency position:

[0106] ,

[0107] in, The dominant frequency position of the array-synthesized vibration signal is the extracted ultrasonic array feature.

[0108] Step 3) Calculate the main frequency synchronization index, normalized phase stability index and nonlinear coupling index based on the high-frequency current characteristics and ultrasonic array characteristics, and determine the fusion confidence function by weighted summation of the indexes.

[0109] This step extracts frequency, phase, and nonlinear features from the electromagnetic and mechanical modal signals respectively. These features are then fused and evaluated using physical consistency, time-domain / frequency-domain correlation, and environmental compensation mechanisms to ultimately output a unified confidence index. Specifically, the steps include:

[0110] Step 31) Calculate the main frequency synchronization index

[0111] ,

[0112] in, It is characterized by high-frequency current. Features of ultrasound arrays To set the tolerance difference, This is an indicator of main frequency synchronization. If... If the electromagnetic and mechanical excitation frequencies are consistent, then it is assumed that they are the same.

[0113] Step 32) Calculate the normalized phase stability index

[0114] If the difference between the main peak frequencies of the high-frequency current signal and the array-synthesized vibration signal obtained by superimposing the ultrasonic vibration signal is within a set tolerance range... Within the range, the resonant dominant frequency is defined as:

[0115] ,

[0116] in, It is characterized by high-frequency current. Features of ultrasound arrays This is the resonant main frequency.

[0117] The high-frequency current signal and the array-synthesized vibration signal are respectively analyzed with a center frequency of... bandwidth is Narrowband filtering is used to extract the main frequency carrier:

[0118] ,

[0119] in, Indicates a high-frequency current signal. This indicates the array synthesized vibration signal. The center frequency is Bandwidth is Narrowband filter, This represents the main frequency carrier of a high-frequency current signal. This represents the main frequency carrier of the array-synthesized vibration signal;

[0120] Perform Hilbert transform on the main frequency carrier of the high-frequency current signal and the array-synthesized vibration signal to extract the instantaneous phase:

[0121] ,

[0122] ,

[0123] in, Represents the Hilbert transform. This represents the analytic signal of the high-frequency current after the Hilbert transform. This represents the analytic signal of ultrasound after Hilbert transform, where j is the imaginary unit. This indicates the calculation of the phase angle of a complex number. Represents the instantaneous phase of a high-frequency current signal. This indicates the instantaneous phase of the ultrasonic signal.

[0124] Constructing phase difference:

[0125] ,

[0126] If the phase difference The standard deviation within the preset duration is lower than This indicates the presence of phase-locked loop. Calculate the normalized phase stability index:

[0127] ,

[0128] in, , representing the normalized phase stability index, This represents the standard deviation. If the phase difference... The standard deviation over the preset duration is greater than or equal to If no phase-locked phenomenon is observed on the surface, this set of data should be discarded.

[0129] Step 33) Calculate the nonlinear coupling index

[0130] Step 331) Construct a nonlinear candidate frequency set for the high-frequency current signal.

[0131] Perform a Fourier transform on the high-frequency current signal I(t) to identify significant spectral peaks other than its dominant frequency and its integer harmonics. Two of the peak frequencies are set as Calculate the intermodulation frequency and the combination frequency:

[0132] , ,

[0133] ,

[0134] in, This represents the intermodulation frequency. There are multiple ways to calculate the intermodulation frequency; this embodiment lists three methods. Only these three intermodulation frequencies need to be calculated: ; Indicates the combination frequency. ,and It is used to capture the complex frequency mixing modes that may be generated by nonlinear systems.

[0135] A nonlinear candidate frequency set for high-frequency current signals is constructed based on the calculated intermodulation frequencies and combination frequencies. The calculated result of the combined frequency may not necessarily have a corresponding frequency component in the original signal. In this embodiment, only the combined frequencies for which a corresponding frequency component can be found in the original signal are included in the nonlinear candidate frequency set of the constructed high-frequency current signal.

[0136] Step 332) Construct a set of nonlinear candidate frequencies for the ultrasonic vibration signal.

[0137] Synthetic vibration signals from array Perform Fourier transform to extract subharmonic components and fractional harmonics:

[0138] ,

[0139] ,

[0140] in, , Indicates array-synthesized vibration signal main frequency; Indicates the subharmonic component. This represents a fractional multiple of the frequency.

[0141] A set of nonlinear candidate frequencies for ultrasonic vibration signals is constructed based on the calculated subharmonic components and fractional harmonics. .

[0142] Step 333) Calculate the nonlinear coupling index

[0143] Construct the intersection of the nonlinear candidate frequency sets of the high-frequency current signal and the ultrasonic vibration signal: This refers to the nonlinear frequency term that appears simultaneously in both modes.

[0144] The nonlinear coupling index is calculated based on the intersection:

[0145] ,

[0146] in, It is a nonlinear coupling index used to measure the degree of consistency of nonlinear frequency components in a two-mode system.

[0147] Step 34) Calculate the fusion confidence function

[0148] Based on the main frequency synchronization index Normalized phase stability index Nonlinear coupling index Construct the fusion confidence function C:

[0149] ,

[0150] Among them, confidence level C This is used to determine whether the "resonance common source" condition has been met. It is an adaptive weight that takes into account factors such as ambient temperature, cable structure, and operating conditions. The initial weights of each factor are determined by a preset mapping rule and then normalized.

[0151] In this embodiment, the mapping rules are as follows: the initial weight corresponding to the ambient temperature is determined based on the degree of difference between the current temperature and the reference temperature; the initial weight corresponding to the cable structure is determined based on the shielding complexity, joint type and insulation process used; and the initial weight corresponding to the operating condition is determined based on the magnitude of the load current.

[0152] Step 4) Determine whether resonance exists based on the fusion confidence function. If it exists, locate the resonance source.

[0153] Step 41) Resonance Judgment

[0154] In this embodiment, if the confidence function is fused If the signal is positive, then it is considered that physical resonance has occurred at the cable joint, which is highly reliable, and step 42 is executed; otherwise, it is considered that no resonance has occurred.

[0155] Step 42) Resonant source location

[0156] The propagation speed of ultrasonic vibration signals in cable insulation depends on the type of insulation material and temperature. Therefore, this embodiment first corrects the ultrasonic velocity using the following formula:

[0157] ,

[0158] in, It is the reference speed of sound (such as in polyethylene). ), It is the temperature coefficient of sound speed, and its unit is... , It is the temperature change relative to a reference.

[0159] Subsequently, by utilizing the difference in propagation speed between dual-mode signals (electromagnetic waves and sound waves) in different propagation media, combined with the direction-finding characteristics of the ultrasonic array, the three-dimensional spatial positioning of the resonant source was achieved. The propagation speed of the high-frequency current signal (electromagnetic mode) is denoted as... (Approximately the speed of light), the propagation speed of ultrasonic vibration signals in the cable insulation medium is denoted as... If a resonant event simultaneously excites a current signal and a mechanical wave at position (x,y,z), the two will arrive at various sensors with different time delays, thereby establishing a set of time difference equations.

[0160] Let the vibration source point be The position of the i-th ultrasonic array sensor is Calculate the propagation time of the ultrasonic signal:

[0161] ,

[0162] in, Let be the propagation time of the i-th ultrasonic array sensor;

[0163] The propagation time of electromagnetic signals from high-frequency currents (approximately considered instantaneous). ;

[0164] The arrival time difference between the electromagnetic signal of the high-frequency current and the ultrasonic signal of the i-th ultrasonic array sensor is: The calculation formula is as follows:

[0165] ,

[0166] By minimizing the squared residual between the theoretical propagation time and the actual time difference, a nonlinear least squares positioning model is constructed, and a nonlinear least squares optimization problem is established:

[0167] ,

[0168] Solve the nonlinear least squares optimization problem to obtain the three-dimensional spatial coordinates. This enables the localization of the resonant source.

[0169] This embodiment does not limit the solution method for the nonlinear least squares optimization problem. The solution methods that can be used include, but are not limited to, those that can achieve the purpose of this invention.

[0170] Step 5) Combine the resonance judgment results and the resonance source location results to output an early warning.

[0171] An alarm is output by combining the dual-mode fusion judgment result and the resonant source location result.

[0172] Example 2

[0173] This embodiment, based on Embodiment 1, provides a specific implementation method for adaptive weights in the fusion confidence function. The specific mapping rules are shown in Table 1.

[0174] Table 1

[0175]

[0176] Based on the initial weights corresponding to ambient temperature, cable structure, and operating conditions. , , Normalization is performed to obtain adaptive weights:

[0177]

[0178]

[0179]

[0180] Example 3

[0181] The electronic device of this invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in read-only memory (ROM) or loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The CPU, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0182] Multiple components in the device are connected to the I / O interface, including: input units such as keyboards and mice; output units such as various types of displays and speakers; storage units such as disks and optical discs; and communication units such as network interface cards (NICs), modems, and wireless transceivers. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0183] The processing unit executes the various methods and processes described above, such as method steps 1)-5). For example, in some embodiments, method steps 1)-5) may be implemented as a computer software program tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via ROM and / or a communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of method steps 1)-5) described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute method steps 1)-5) by any other suitable means (e.g., by means of firmware).

[0184] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0185] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0186] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0187] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for real-time diagnosis of cable joint resonance, characterized in that, The method includes the following steps: Acquire high-frequency current signals from a high-frequency current sensor and ultrasonic vibration signals from an ultrasonic sensor array; The high-frequency current signal and the ultrasonic vibration signal are synchronized, and the high-frequency current features and ultrasonic array features are extracted. Based on the high-frequency current characteristics and ultrasonic array characteristics, the main frequency synchronization index, normalized phase stability index, and nonlinear coupling index are calculated, and the weighted summation of the indices is used to determine the fusion confidence function. The existence of resonance is determined based on the fusion confidence function. If resonance exists, the source of resonance is located.

2. The real-time diagnostic method for cable joint resonance according to claim 1, characterized in that, The extraction of the high-frequency current features specifically involves performing a Fourier transform on the high-frequency current signal I(t) to extract the dominant frequency position. ， in, Indicates Fourier transform, This means searching across all possible frequencies f to maximize the objective function. This refers to the dominant frequency position of the high-frequency current signal, i.e., the extracted high-frequency current characteristics; The extraction of ultrasonic array features specifically involves: weighted superposition of ultrasonic vibration signals collected by multiple ultrasonic sensors in the ultrasonic sensor array to obtain a synthesized array vibration signal. ， in, Let N be the ultrasonic vibration signal acquired by the i-th ultrasonic sensor, and N be the number of ultrasonic sensors. To synthesize vibration signals for arrays; Synthetic vibration signals from array Perform a Fourier transform to extract the dominant frequency position: ， in, The dominant frequency position of the array-synthesized vibration signal is the extracted ultrasonic array feature.

3. The real-time diagnostic method for cable joint resonance according to claim 1, characterized in that, The calculation method for the main frequency synchronization index is as follows: ， in, It is characterized by high-frequency current. Features of ultrasound arrays To set the tolerance difference, It is a key indicator of frequency synchronization.

4. The real-time diagnostic method for cable joint resonance according to claim 1, characterized in that, The normalized phase stability index is calculated as follows: If the difference between the main peak frequencies of the high-frequency current signal and the array-synthesized vibration signal obtained by superimposing the ultrasonic vibration signal is within a set tolerance range... Within the range, the resonant dominant frequency is defined as: ， in, It is characterized by high-frequency current. Features of ultrasound arrays This is the resonant main frequency point; The high-frequency current signal and the array-synthesized vibration signal are respectively analyzed with a center frequency of... bandwidth is Narrowband filtering is used to extract the main frequency carrier: ， in, Indicates a high-frequency current signal. This indicates the array-synthesized vibration signal. The center frequency is Bandwidth is Narrowband filter, This represents the main frequency carrier of a high-frequency current signal. This represents the main frequency carrier of the array-synthesized vibration signal; Perform Hilbert transform on the main frequency carrier of the high-frequency current signal and the array-synthesized vibration signal to extract the instantaneous phase: ， ， in, Represents the Hilbert transform. This represents the analytic signal of the high-frequency current after the Hilbert transform. This represents the analytic signal of ultrasound after Hilbert transform, where j is the imaginary unit. This indicates the calculation of the phase angle of a complex number. Represents the instantaneous phase of a high-frequency current signal. Indicates the instantaneous phase of the ultrasonic signal; Constructing phase difference: ， If the phase difference The standard deviation within the preset duration is lower than This indicates the presence of phase-locked loop. Calculate the normalized phase stability index: ， in, , representing the normalized phase stability index, It represents the standard deviation.

5. The real-time diagnostic method for cable joint resonance according to claim 1, characterized in that, The calculation method for the nonlinear coupling index is as follows: Perform a Fourier transform on the high-frequency current signal I(t) to identify significant spectral peaks other than its dominant frequency and its integer harmonics. Two of the peak frequencies are set as Calculate the intermodulation frequency and the combination frequency: , ， ， in, ,and ; Indicates the intermodulation frequency. Indicates the combination frequency; A nonlinear candidate frequency set for high-frequency current signals is constructed based on the calculated intermodulation frequencies and combination frequencies. ; Synthetic vibration signals from array Perform Fourier transform to extract subharmonic components and fractional harmonics: ， ， in, , Indicates array-synthesized vibration signal main frequency; Indicates the subharmonic component. Indicates fractional frequency; A set of nonlinear candidate frequencies for ultrasonic vibration signals is constructed based on the calculated subharmonic components and fractional harmonics. ; Construct the intersection of the nonlinear candidate frequency sets of the high-frequency current signal and the ultrasonic vibration signal: This refers to the nonlinear frequency term that appears simultaneously in both modes; The nonlinear coupling index is calculated based on the intersection: ， in, It is a nonlinear coupling index.

6. The method for real-time diagnosis of cable joint resonance according to claim 1, characterized in that, The calculation method for the fusion confidence function is as follows: ， in, To fuse the confidence function, As a primary frequency synchronization indicator, This is a normalized phase stability index. It is a nonlinear coupling index. It is an adaptive weight that takes into account factors such as ambient temperature, cable structure, and operating conditions. The initial weights corresponding to each factor are determined by a preset mapping rule and then normalized. Specifically, the initial weight corresponding to the ambient temperature is determined based on the difference between the current temperature and the reference temperature; the initial weight corresponding to the cable structure is determined based on the shielding complexity, joint type, and insulation process used; and the initial weight corresponding to the operating conditions is determined based on the magnitude of the load current.

7. The real-time diagnostic method for cable joint resonance according to claim 1, characterized in that, The method for locating the resonant source is as follows: Let the propagation speed of a high-frequency current signal be . The propagation speed of ultrasonic vibration signals in the cable insulation medium is Let the vibration source point be... The position of the i-th ultrasonic array sensor is Calculate the propagation time of the ultrasonic signal: ， in, Let be the propagation time of the i-th ultrasonic array sensor; electromagnetic signal propagation time of high-frequency current ; The time difference between the arrival of the high-frequency current electromagnetic signal and the ultrasonic signal from the i-th ultrasonic array sensor is: The calculation formula is as follows: ， By minimizing the squared residual between the theoretical propagation time and the actual time difference, a nonlinear least squares positioning model is constructed, and a nonlinear least squares optimization problem is established: ， Solve the nonlinear least squares optimization problem to obtain the three-dimensional spatial coordinates. This enables the localization of the resonant source.

8. The method for real-time diagnosis of cable joint resonance according to claim 7, characterized in that, The method for calculating the propagation speed of the ultrasonic vibration signal in the cable insulation medium is as follows: ， in, It is the reference speed of sound. It is the temperature coefficient of sound speed. It is the temperature change relative to a reference.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1 to 8.

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 8.

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