Real-time cable joint resonance diagnosis method and device and medium

Abstract

The invention relates to a cable joint resonance real-time diagnosis method and device and a medium, and belongs to the technical field of power equipment state monitoring, and the method comprises the following steps: obtaining a high-frequency current signal collected by a high-frequency current sensor and an ultrasonic vibration signal collected by an ultrasonic sensor array; performing signal synchronization on the high-frequency current signal and the ultrasonic vibration signal, and extracting a high-frequency current feature and an ultrasonic array feature; calculating a dominant frequency synchronization index, a normalized phase stability index and a nonlinear coupling index based on the high-frequency current characteristics and the ultrasonic array characteristics, and performing weighted summation to determine a fusion confidence coefficient function; and judging whether resonance exists or not based on the fusion confidence coefficient function, and if so, carrying out resonance source positioning. Compared with the prior art, the method has the advantages of high precision, low false alarm and high adaptability, and is suitable for key power system scenes such as new energy grid connection, urban smart power grids and wind power.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power equipment state monitoring, in particular to a cable joint resonance real-time diagnosis method, device and medium. BACKGROUND

[0002] With the high proportion of new energy grid connection and the continuous rise of urban power grid load density, the operation reliability of high-voltage cable joints has become a core factor affecting the safety of the power system. Especially in the scenario of photovoltaic and wind power fluctuation output, the resonance failure rate of cable joints presents an explosive growth. Industry statistics show that the resonance proportion of 66kV and above cable failures has increased from 12% five years ago to 27% currently. Such failures not only lead to frequent unplanned power outages, but also may cause chain accidents such as insulation breakdown. There is an urgent need for real-time early warning of resonance in high-reliability scenarios such as offshore wind power transmission projects and urban comprehensive pipe galleries. However, the traditional detection methods have fundamental limitations, resulting in significant direct economic losses due to misjudgment and positioning loss every year, which seriously hinders the construction process of new power systems.

[0003] Current cable joint state monitoring mainly relies on three types of technical routes. The electrical parameter method based on high-frequency current (such as Chinese patent CN1134667A) realizes resonance detection by analyzing 1-30MHz harmonics, but the background harmonic interference of the power grid leads to a false positive rate of more than 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 electromagnetic resonance vibration from environmental mechanical noise; the system-level impedance analysis method (such as Chinese patent CN114994478A) can diagnose power grid resonance, but the spatial resolution is more than 10 meters, which cannot locate the fault point inside the joint.

[0004] The above technologies face three core challenges. At the mechanism level, traditional methods ignore the electromagnetic-mechanical energy coupling effect in the resonance process and lack quantitative correlation modeling of temperature deformation and resonance frequency; at the implementation level, the single-sensor solution has a significant detection blind area, with a false negative rate of frequency division resonance of up to 100%, and a software-level time synchronization error of more than 100 microseconds leading to phase analysis failure; at the functional level, existing technologies cannot achieve fault location, and maintenance personnel are forced to replace the high-value joint as a whole, increasing the maintenance cost by more than 300%. These defects make the power system unable to cope with new resonance risks brought by new energy grid connection.

[0005] Therefore, there is a need for a method that can accurately detect resonance. SUMMARY

[0006] The purpose of the present application is to overcome the defects of high false positive rate, response lag, and difficult positioning of the prior art, and to provide a cable joint resonance real-time diagnosis method, device and medium.

[0007] The object of the present application can be achieved by the following technical solutions: According to a first aspect of the present application, a cable joint resonance real-time diagnosis method is provided, which comprises the following steps: obtaining a high-frequency current signal collected by a high-frequency current sensor and an ultrasonic vibration signal collected by an ultrasonic sensor array; synchronizing the high-frequency current signal and the ultrasonic vibration signal, and extracting high-frequency current features and ultrasonic array features; calculating a main frequency synchronization index, a normalized phase stability index and a nonlinear coupling index based on the high-frequency current features and the ultrasonic array features, and performing weighted summation on the indexes to determine a fusion confidence function; judging whether there is resonance based on the fusion confidence function, and if there is, performing resonance source positioning.

[0008] The extraction of the high-frequency current features is specifically: performing Fourier transform on the high-frequency current signal I(t) to extract the main frequency position: , wherein, represents Fourier transform, represents searching in all possible frequencies f to maximize the objective function, is the main frequency position of the high-frequency current signal, i.e., the extracted high-frequency current features; The extraction of the ultrasonic array features is specifically: performing weighted superposition on the ultrasonic vibration signals collected by the multiple ultrasonic sensors in the ultrasonic sensor array to obtain an array synthesized vibration signal: , wherein, is the ultrasonic vibration signal collected by the i-th ultrasonic sensor, and N is the number of ultrasonic sensors, is the array synthesized vibration signal; performing Fourier transform on the array synthesized vibration signal to extract the main frequency position: , wherein, is the main frequency position of the array synthesized vibration signal, i.e., the extracted ultrasonic array features.

[0009] The calculation method of the main frequency synchronization index is: , wherein, is the high-frequency current feature, is the ultrasonic array feature, is a set bandwidth tolerance, The main frequency synchronization index.

[0010] The calculation method of the normalized phase stability index is: If the main peak frequency difference of the high-frequency current signal and the array synthesized vibration signal obtained by superimposing the ultrasonic vibration signal is within the set bandwidth tolerance , the resonance main frequency point is defined as: , Wherein, is the high-frequency current characteristic, is the ultrasonic array characteristic, is the resonance main frequency point; The high-frequency current signal and the array synthesized vibration signal are respectively subjected to narrowband filtering with the center frequency and the bandwidth , and the main frequency carrier is extracted: , Wherein, represents the high-frequency current signal, represents the array synthesized vibration signal, represents the narrowband filter with the center frequency and the bandwidth , represents the main frequency carrier of the high-frequency current signal, represents the main frequency carrier of the array synthesized vibration signal; The main frequency carriers of the high-frequency current signal and the array synthesized vibration signal are subjected to Hilbert transform, and the instantaneous phase is extracted: , , Wherein, represents the Hilbert transform, represents the analytic signal of the high-frequency current after the Hilbert transform, represents the analytic signal of the ultrasonic after the Hilbert transform, and j is the imaginary unit, represents the phase angle of the complex number, represents the instantaneous phase of the high-frequency current signal, represents the instantaneous phase of the ultrasonic signal; The phase difference is constructed: , If the standard deviation of the phase difference within the preset duration is lower than , it indicates that there is phase locking phenomenon, and the normalized phase stability index is calculated: , Wherein, denotes the normalized phase stability index, denotes the standard deviation.

[0011] The calculation method of the nonlinear coupling index is: Fourier transform is performed on the high-frequency current signal I(t) to identify significant spectral peaks other than the main frequency and its integer multiple frequency components , and set two of the peak frequencies as , and calculate the intermodulation frequency and the combination frequency: , , , wherein, , and ; denotes the intermodulation frequency, denotes the combination frequency; Based on the calculated intermodulation frequency and combination frequency, a nonlinear candidate frequency set of the high-frequency current signal is constructed ; Fourier transform is performed on the array synthesized vibration signal to extract the subharmonic component and the fractional multiple frequency: , , wherein, , denotes the main frequency of the array synthesized vibration signal ; denotes the subharmonic component, denotes the fractional multiple frequency; Based on the calculated subharmonic component and fractional multiple frequency, a nonlinear candidate frequency set of the ultrasonic vibration signal is constructed ; The intersection of the nonlinear candidate frequency sets of the high-frequency current signal and the ultrasonic vibration signal is constructed: , i.e. the nonlinear frequency items appearing in both modalities at the same time; Based on the intersection, the nonlinear coupling index is calculated: , wherein, is the nonlinear coupling index.

[0012] The calculation method of the fusion confidence function is: , wherein, is the fusion confidence function, is the main frequency synchronization index, a phase stability index is normalized, a non-linear coupling index is normalized, is an adaptive weight considering environmental temperature, cable structure and working condition factors, and is obtained by determining initial weights corresponding to each factor through a preset mapping rule and performing normalization processing, the mapping rule is specifically: the initial weight corresponding to the environmental temperature is determined according to the difference between the current temperature and the reference temperature, the initial weight corresponding to the cable structure is determined according to the shielding complexity, the joint type and the adopted insulation process, and the initial weight corresponding to the working condition is determined according to the size of the load current.

[0013] The method for positioning the resonance source is specifically: Let the propagation speed of the high-frequency current signal be The propagation speed of the ultrasonic vibration signal in the cable insulation medium is Let the vibration source point be The position of the i-th ultrasonic array sensor is The ultrasonic signal propagation time is calculated as , Wherein, is the propagation time of the i-th ultrasonic array sensor; The electromagnetic signal propagation time of the high-frequency current is ; 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: , By minimizing the residual square 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 constructed: , Solving the nonlinear least squares optimization problem, the three-dimensional space coordinates are obtained, and the resonance source positioning is realized.

[0014] The calculation method of the propagation speed of the ultrasonic vibration signal in the cable insulation medium is: , Wherein, is the reference sound speed, is the sound speed temperature coefficient, is the temperature change relative to the reference.

[0015] According to the second aspect of the present application, an electronic device is provided, comprising a memory and a processor, the memory stores a computer program, and the processor implements the method when executing the program.

[0016] According to a third aspect of the present application, a computer readable storage medium is provided, having stored thereon a computer program which, when executed by a processor, implements the method.

[0017] Compared with the prior art, the present application has the following beneficial effects: (1) The present application firstly synchronously collects the electromagnetic and vibration response signals inside the cable through a high-sensitivity current sensor and a ring-shaped ultrasonic array, and performs microsecond-level time sequence alignment, then extracts key features from the two modalities, and constructs a multi-dimensional fusion criterion based on frequency synchronization, phase consistency and nonlinear coupling, fuses multiple feature indexes through a dynamic weight model, accurately determines whether resonance occurs, and constructs a time difference equation set combining the propagation speed difference of the two modalities, realizes centimeter-level three-dimensional positioning, and improves the resonance positioning accuracy and real-time diagnosis.

[0018] (2) The present application firstly fuses and analyzes high-frequency current signals and ultrasonic vibration signals in a synchronous manner, breaks through the limitations of traditional electrical single-mode detection, realizes mutual verification of resonance events through the physical coupling relationship of electromagnetic and acoustic signals, greatly reduces the false alarm rate, and enhances the recognition ability of complex fault types.

[0019] (3) The present application proposes a fusion criterion based on frequency alignment, phase consistency, nonlinear intermodulation coupling and other independent physical features, and introduces adaptive dynamic weights to comprehensively evaluate the confidence of the resonance state, realize more robust and accurate judgment logic, and have good environmental adaptability and generalization ability.

[0020] (4) The present application utilizes the propagation speed difference of electromagnetic waves and sound waves in different media, combines array ultrasonic direction finding mechanism, performs high-precision time difference positioning, can realize centimeter-level resonance source spatial inversion, and significantly improves the resolution and reliability of fault positioning. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flowchart of the method of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should fall within the scope of protection of the present application.

[0023] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Unless otherwise defined, the terms "one", "a", "an" and "the" used in the present application do not denote a limitation of quantity but denote the presence of at least one of the referenced item. The terms "comprising", "including", "containing", "have" and any variations thereof in the present application are intended to cover a non-exclusive inclusion; for example, a process, method, system, product or apparatus that comprises a list of steps or units (elements) is not necessarily limited to the listed steps or units but can include additional steps or units not expressly listed or can include additional steps or units inherent to such process, method, product or apparatus. The terms "connected", "coupled", and similar terms in the present application are not limited to a physical or mechanical connection or coupling, but can include an electrical connection or coupling, whether direct or indirect. The term "plurality" in the present application means two or more. The term "and / or" describes an associated relationship between associated objects, which means that there can be three relationships, for example, "A and / or B" can mean that A exists alone, A and B exist together, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects. The terms "first", "second", "third" and the like in the present application are merely to distinguish similar objects, and do not represent a specific order of the objects.

[0024] Embodiment 1 The embodiment provides a cable joint resonance real-time diagnosis method, aiming at solving the key industry problems of high false alarm rate, lack of positioning ability and slow response speed in traditional detection technology. The method first collects the high-frequency current spectrum signal of the cable joint conductor layer in real time through the embedded high-sensitivity current sensor, simultaneously monitors the surface mechanical vibration signal of the insulating layer by using the annular distributed multi-channel ultrasonic array, and adopts the advanced time synchronization architecture based on satellite timing and hardware level processing to realize the microsecond-level accurate time alignment of the double-mode signals; then the collected signals are subjected to deep collaborative feature extraction: the current side comprehensively analyzes the harmonic amplitude dynamic change characteristics and nonlinear intermodulation distortion phenomena, and the vibration side system extracts the temperature-compensated sound wave propagation speed offset characteristics, fundamental frequency vibration energy distribution and subharmonic resonance characteristics; further, a multi-dimensional physical fusion criterion is constructed: by strictly verifying the fundamental frequency synchronization characteristics of the electromagnetic signal and the mechanical vibration signal, the direction consistency of the electromagnetic dispersion effect and the acoustic propagation path, and the mutual verification relationship of the nonlinear distortion characteristics and the mechanical subharmonic, an adaptive dynamic weight calculation model is adopted to comprehensively evaluate the confidence level of resonance occurrence; when the confidence level reaches the preset threshold, the significant difference between the electromagnetic wave and the sound wave in the medium is accurately calculated, a high-precision time difference equation set is established, and the three-dimensional space accurate positioning of the resonance source is realized by the optimized advanced mathematical algorithm, and the early warning mechanism is realized based on the early change trend of the nonlinear characteristics. The method has the advantages of high precision, low false alarm and strong adaptability, and is suitable for key power system scenes such as new energy grid connection, urban smart grid and wind power, and has wide engineering application prospect.

[0025] Specifically, as shown in the method comprises the following steps: Figure 1 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.

[0026] Firstly, a single high-sensitivity high-frequency current transformer is arranged near the joint conductor for real-time collection of high-frequency components in the current signal inside the cable. The typical sampling frequency is above 100 MHz, which can cover the resonance characteristic frequency band of 3 MHz to 100 MHz.

[0027] Secondly, several ultrasonic sensors are arranged circumferentially on the outer surface of the joint insulation to form an annular array structure, and the number is usually 4-16. The sensor type can be a piezoelectric accelerometer with high sensitivity and wide frequency band response capability. The vibration signal collected by the ultrasonic array is a multi-channel time series, which can reflect the multi-point resonance response characteristics of the structure.

[0028] Step 2) Signal synchronization is performed on the high-frequency current signal and the ultrasonic vibration signal, and high-frequency current features and ultrasonic array features are extracted.

[0029] Step 21) Signal synchronization​ This embodiment is based on GPS-PPS+FPGA hardware synchronization architecture to solve the problem of cross-modal signal alignment: 1) Clock reference: GPS receiver outputs 1PPS (second pulse) signal, time accuracy ±100ns; 2) Timestamp generation: FPGA triggers on the rising edge of the pulse, adds 64-bit nanosecond-level timestamp to the double-channel ADC sampling data; 3) Delay compensation: calculate the transmission delay through the calibration cable: , Where, is the cable length, is the signal propagation speed, , is the speed of light in vacuum, is the transmission delay.

[0030] According to the calculated transmission delay, the signal is calibrated.

[0031] Step 22) High-frequency current feature extraction Fourier transform is performed on the high-frequency current signal I(t) to extract the main frequency position: , Where, denotes the Fourier transform, denotes searching in all possible frequencies f to maximize the objective function, is the main frequency position of the high-frequency current signal, i.e. the extracted high-frequency current feature.

[0032] Step 23) Ultrasonic array feature extraction The ultrasonic vibration signals collected by multiple ultrasonic sensors in the ultrasonic sensor array are weighted and superimposed to obtain an array synthesis vibration signal: , Where, is the ultrasonic vibration signal collected by the i-th ultrasonic sensor, and N is the number of ultrasonic sensors, is the array synthesis vibration signal; Fourier transform is performed on the array synthesis vibration signal to extract the main frequency position: , Where, is the main frequency position of the array synthesis vibration signal, i.e. the extracted ultrasonic array feature.

[0033] Step 3) Based on the high-frequency current characteristics and the ultrasonic array characteristics, the main frequency synchronization index, the normalized phase stability index and the nonlinear coupling index are calculated, and the weighted sum of the indexes is performed to determine the fusion confidence function.

[0034] This step extracts frequency, phase, and nonlinear characteristics from electromagnetic and mechanical modal signals, performs fusion evaluation through physical consistency, time / frequency domain correlation, and environmental compensation mechanisms, and ultimately outputs a unified confidence index. Specifically, it includes the following steps: Step 31) Calculate the main frequency synchronization index , in, is the high frequency current characteristic, is the ultrasound array feature, To set the bandwidth tolerance, Is the main frequency synchronization indicator. , the electromagnetic and mechanical excitation frequencies are considered to be consistent.

[0035] Step 32) Calculate the normalized phase stability index If the main peak frequency difference between the high-frequency current signal and the array synthetic vibration signal obtained by superimposing the ultrasonic vibration signal is within the set bandwidth tolerance Within the range, the main resonant frequency point is defined as: , in, is the high frequency current characteristic, is the ultrasound array feature, is the main resonant frequency.

[0036] The high frequency current signal and the array synthetic vibration signal are respectively subjected to the center frequency , the bandwidth is Narrowband filtering to extract the main frequency carrier: , in, Represents a high-frequency current signal, represents the array synthetic vibration signal, Indicates the center frequency is , bandwidth is Narrowband filter, Represents the main frequency carrier of the high-frequency current signal, Represents the main frequency carrier of the array synthetic vibration signal; Perform Hilbert transform on the main frequency carrier of the high-frequency current signal and the array synthetic vibration signal to extract the instantaneous phase: , , wherein, denotes the Hilbert transform, denotes the analytic signal of the high-frequency current after the Hilbert transform, denotes the analytic signal of the ultrasound after the Hilbert transform, j is the imaginary unit, denotes the phase angle of a complex number, denotes the instantaneous phase of the high-frequency current signal, denotes the instantaneous phase of the ultrasound signal.

[0037] constructing the phase difference: , if the phase difference is less than the standard deviation of the phase difference in the preset duration, it indicates that there is phase-locked phenomenon, and the normalized phase stability index is calculated: , wherein, , denotes the normalized phase stability index, denotes the standard deviation. If the phase difference is greater than or equal to the standard deviation of the phase difference in the preset duration, it indicates that there is no phase-locked phenomenon, and the data is discarded.

[0038] Step 33) calculating the nonlinear coupling index Step 331) constructing the nonlinear candidate frequency set of the high-frequency current signal performing Fourier transform on the high-frequency current signal I(t) to identify significant spectral peaks other than the main frequency and its integer multiple frequency components , setting two peak frequencies among them as , calculating the intermodulation frequency and the combination frequency: , , , wherein, denotes the intermodulation frequency, and there are multiple ways to calculate the intermodulation frequency, and the present embodiment lists three kinds, and only these three intermodulation frequencies need to be calculated, that is: ; denotes the combination frequency, , and , which is used to capture the complex frequency mixing mode that the nonlinear system may generate.

[0039] constructing the nonlinear candidate frequency set of the high-frequency current signal based on the calculated intermodulation frequency and combination frequency The calculation result of the combined frequency may not be able to find a corresponding frequency component in the original signal. In the embodiment, only the combined frequency that can find a corresponding frequency component in the original signal is listed in the nonlinear candidate frequency set of the high-frequency current signal.

[0040] Step 332) constructing a nonlinear candidate frequency set of the ultrasonic vibration signal The array synthesis vibration signal Performing Fourier transform to extract the sub-harmonic component and the fractional multiple frequency: , , Among them, , The main frequency of the array synthesis vibration signal is represented by f; The sub-harmonic component is represented by f; The fractional multiple frequency is represented by f.

[0041] Constructing a nonlinear candidate frequency set of the ultrasonic vibration signal based on the calculated sub-harmonic component and the fractional multiple frequency .

[0042] Step 333) calculating the nonlinear coupling index Constructing the intersection of the nonlinear candidate frequency sets of the high-frequency current signal and the ultrasonic vibration signal: That is, the nonlinear frequency items appearing in both modalities.

[0043] Calculating the nonlinear coupling index based on the intersection: , Among them, The nonlinear coupling index is used to measure the consistency degree of the nonlinear frequency components in the dual modalities.

[0044] Step 34) calculating the fusion confidence function According to the main frequency synchronization index , the normalized phase stability index , the nonlinear coupling index , the fusion confidence function C is constructed: , Among them, the confidence C is used to judge whether the "resonance common source" condition is reached. is an adaptive weight considering environmental temperature, cable structure, and working condition factors. The initial weight corresponding to each factor is determined through a preset mapping rule and normalized to obtain.

[0045] In this embodiment, the mapping rule is specifically: the initial weight corresponding to the environmental temperature is determined according to the difference between the current temperature and the reference temperature, the initial weight corresponding to the cable structure is determined according to the shielding complexity, the joint type and the adopted insulation process, and the initial weight corresponding to the working condition is determined according to the size of the load current.

[0046] Step 4) judging whether there is resonance based on the fusion confidence function, if yes, then performing resonance source positioning.

[0047] Step 41) resonance judgment In this embodiment, if the fusion confidence function , it is determined that physical resonance occurs at the cable joint, the credibility is high, and step 42) is executed; otherwise, it is considered that resonance does not occur.

[0048] Step 42) resonance source positioning The propagation speed of the ultrasonic vibration signal in the cable insulation medium depends on the type and temperature of the insulation material, so in this embodiment, the ultrasonic speed is first corrected, and the sound speed correction formula is: , wherein, is the reference sound speed (such as the sound speed in polyethylene ), is the sound speed temperature coefficient, and the unit is , is the temperature change relative to the reference.

[0049] Thereafter, the difference in propagation speed of the dual-mode signal (electromagnetic wave and acoustic wave) in different propagation media is utilized, combined with the direction-finding characteristics of the ultrasonic array, to realize three-dimensional spatial positioning of the resonance source. The propagation speed of the high-frequency current signal (electromagnetic mode) is denoted as (approximately the speed of light), and the propagation speed of the ultrasonic vibration signal in the cable insulation medium is denoted as If a resonance event simultaneously excites current signals and mechanical waves at a position (x, y, z), the two will arrive at various types of sensors with different time delays, and thus a time difference equation set can be established.

[0050] Let the resonance source point be , the position of the i-th ultrasonic array sensor be , and the ultrasonic signal propagation time be calculated: , wherein, is the propagation time of the i-th ultrasonic array sensor; the electromagnetic signal propagation time of the high-frequency current (approximately considered as instantaneous) ; 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: , By minimizing the residual square between the theoretical propagation time and the actual time difference, a nonlinear least square positioning model is constructed, and a nonlinear least square optimization problem is constructed: , Solving the nonlinear least square optimization problem, obtaining three-dimensional space coordinates , realizing resonance source positioning.

[0051] The embodiment does not limit the solving method of the nonlinear least square optimization problem, and the solving method that can be used includes but is not limited to, which can achieve the purpose of the application.

[0052] Step 5) combining the resonance judgment result and the resonance source positioning result to perform early warning output.

[0053] Combining the dual-mode fusion judgment result and the resonance source positioning result to perform alarm output.

[0054] Embodiment 2 Based on the embodiment 1, the embodiment provides a specific implementation mode of fusing adaptive weight in the confidence function. The specific mapping rule is shown in Table 1.

[0055] Table 1

[0056] According to the initial weight corresponding to the environmental temperature, the cable structure and the working condition factor , , , normalization is performed to obtain the adaptive weight:

[0057]

[0058]

[0059] Embodiment 3 The electronic device of the application includes a central processing unit (CPU) which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded into a random access memory (RAM) from a storage unit. In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM and RAM are connected to each other through a bus. An input / output (I / O) interface is also connected to the bus.

[0060] A number of components in the device are connected to the I / O interface, including: input units, such as a keyboard, a mouse, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as a magnetic disk, an optical disk, etc.; and communication units, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunication networks.

[0061] The processing unit performs the various methods and processes described above, such as method steps 1) - 5). For example, in some embodiments, the method steps 1) - 5) can be implemented as a computer software program tangibly embodied in a machine readable medium, such as the storage unit. In some embodiments, portions or all of the computer program can be loaded and / or installed onto the device via the ROM and / or the communication unit. When the computer program is loaded onto the RAM and executed by the CPU, one or more of the method steps 1) - 5) described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform the method steps 1) - 5) by way of other any suitable means, such as by way of firmware.

[0062] The functionality described above in this document can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, example types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0063] Program code for carrying out methods of the present application 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 apparatus, such that the program code, when executed by the processor or controller, causes the functions / operations specified in the flow charts and / or block diagrams to be implemented. The program code can execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

[0064] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable storage media can include, without limitation, 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 can include one or more lines of electrical wire, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fiber, portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0065] The above description is only specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A real-time diagnosis method for cable joint resonance, characterized in that: The method comprises the following steps: Acquire a high-frequency current signal collected by a high-frequency current sensor and an ultrasonic vibration signal collected by an ultrasonic sensor array; performing signal synchronization on the high-frequency current signal and the ultrasonic vibration signal, and extracting high-frequency current features and ultrasonic array features; Calculating a main frequency synchronization index, a normalized phase stability index, and a nonlinear coupling index based on the high-frequency current characteristics and the ultrasonic array characteristics, and performing weighted summation on the indexes to determine a fusion confidence function; Based on the fusion confidence function, it is determined whether resonance exists, and if so, the resonance source is located.

2. A cable joint resonance real-time diagnosis method according to claim 1, characterized in that: The extraction of the high-frequency current feature is specifically as follows: performing Fourier transform on the high-frequency current signal I(t) to extract the main frequency position: ， in, represents the Fourier transform, Indicates that the objective function is maximized by searching among all possible frequencies f. is the main frequency position of the high-frequency current signal, that is, the extracted high-frequency current feature; The extraction of the ultrasonic array feature is specifically as follows: performing weighted superposition on the ultrasonic vibration signals collected by multiple ultrasonic sensors in the ultrasonic sensor array to obtain an array synthetic vibration signal: ， in, is the ultrasonic vibration signal collected by the i-th ultrasonic sensor, N is the number of ultrasonic sensors, synthesizing a vibration signal for the array; Synthesize vibration signals for arrays Perform Fourier transform and extract the main frequency position: ， in, is the main frequency position of the array synthesized vibration signal, that is, the extracted ultrasonic array feature.

3. A real-time diagnosis method for cable joint resonance according to claim 1, characterized in that: The calculation method of the main frequency synchronization index is: ， in, is the high frequency current characteristic, is the ultrasound array feature, To set the bandwidth tolerance, It is the main frequency synchronization indicator.

4. A real-time diagnosis method for cable joint resonance according to claim 1, characterized in that: The calculation method of the normalized phase stability index is: If the main peak frequency difference between the high-frequency current signal and the array synthetic vibration signal obtained by superimposing the ultrasonic vibration signal is within the set bandwidth tolerance Within the range, the main resonant frequency point is defined as: ， in, is the high frequency current characteristic, is the ultrasound array feature, is the main resonant frequency point; The high frequency current signal and the array synthetic vibration signal are respectively subjected to the center frequency , the bandwidth is Narrowband filtering to extract the main frequency carrier: ， in, Represents a high-frequency current signal, represents the array synthetic vibration signal, Indicates the center frequency is , bandwidth is Narrowband filter, Represents the main frequency carrier of the high-frequency current signal, Represents the main frequency carrier of the array synthetic vibration signal; Perform Hilbert transform on the main frequency carrier of the high-frequency current signal and the array synthetic vibration signal to extract the instantaneous phase: ， ， in, represents the Hilbert transform, represents the analytical signal of the high-frequency current after Hilbert transform, represents the ultrasonic analytical signal after Hilbert transform, j is the imaginary unit, It means to find the phase angle of a complex number, represents the instantaneous phase of the high-frequency current signal, Represents the instantaneous phase of the ultrasonic signal; Constructing phase difference: ， If the phase difference The standard deviation over the preset duration is lower than , it indicates that there is a phase-locked phenomenon, and the normalized phase stability index is calculated: ， in, , represents the normalized phase stability index, Represents standard deviation.

5. The real-time diagnosis method for cable joint resonance according to claim 1, characterized in that: The calculation method of the nonlinear coupling index is: Perform Fourier transform on the high-frequency current signal I(t) to identify significant spectrum peaks other than its main frequency and its integer multiple components , set two of the peak frequencies to , calculate the intermodulation frequencies and combination frequencies: , ， ， in, ,and ; represents the intermodulation frequency, represents the combination frequency; Construct a nonlinear candidate frequency set for high-frequency current signals based on the calculated intermodulation frequencies and combination frequencies ; Synthesize vibration signals for arrays Perform a Fourier transform to extract subharmonic components and fractional multiples: ， ， in, , Represents the array synthetic vibration signal The main frequency; represents the subharmonic component, Indicates fractional frequency; Constructing a nonlinear candidate frequency set for ultrasonic vibration signals based on calculated subharmonic components and fractional harmonics ; Construct the intersection of the nonlinear candidate frequency set of the high-frequency current signal and the ultrasonic vibration signal: , that is, the nonlinear frequency terms that appear simultaneously in the two modes; The nonlinear coupling index is calculated based on the intersection: ， in, is an indicator of nonlinear coupling.

6. A real-time diagnosis method for cable joint resonance according to claim 1, characterized in that: The calculation method of the fusion confidence function is: ， in, is the fusion confidence function, Is the main frequency synchronization indicator, is the normalized phase stability index, is the nonlinear coupling index, It is an adaptive weight that takes into account the ambient temperature, cable structure, and working condition factors. The initial weight corresponding to each factor is determined by a preset mapping rule and normalized. The specific mapping rule is as follows: the initial weight corresponding to the ambient temperature is determined according to the degree of difference between the current temperature and the reference temperature; the initial weight corresponding to the cable structure is determined according to the shielding complexity, the connector type, and the insulation process used; the initial weight corresponding to the working condition is determined according to the size of the load current.

7. A real-time diagnosis method for cable joint resonance according to claim 1, characterized in that: The method for locating the resonance source is specifically as follows: The propagation speed of high-frequency current signal is , the propagation speed of ultrasonic vibration signal in cable insulation medium is , let the vibration source point be , the position of the i-th ultrasonic array sensor is , calculate the ultrasonic signal propagation time: ， in, is the propagation time of the i-th ultrasonic array sensor; Electromagnetic signal propagation time of high-frequency current ; 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: ， By minimizing the square of the residual between the theoretical propagation time and the actual time difference, a nonlinear least squares positioning model is constructed to formulate a nonlinear least squares optimization problem: ， Solve the nonlinear least squares optimization problem and obtain the three-dimensional space coordinates , realizing the resonance source positioning.

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

9. An electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the program, the method according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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