Electrical equipment early fault diagnosis method, system, equipment and medium

Abstract

The invention belongs to the technical field of power systems, and discloses an electrical equipment early fault diagnosis method, system, equipment and medium, and the method comprises the steps: collecting a fault current signal of the electrical equipment; performing multi-scale time-frequency analysis on the fault current signal to obtain a high-frequency frequency-domain signal and a low-frequency frequency-domain signal of each scale; performing frequency domain signal reconstruction according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal; performing difference extreme point calculation on the obtained time domain signal to obtain a difference extreme point; and the first-order difference extreme point appearing at the first time is used as an intermittent fault occurrence moment. According to the method, the complexity of intermittent breakdown transient signals can be better handled, so that the accuracy and the reliability of fault diagnosis of the electrical equipment are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to an early fault diagnosis method, system, equipment and medium for electrical equipment. Background Art

[0002] Before electrical equipment fails due to insulation degradation, there is often an early fault stage with intermittent breakdown fault characteristics. By detecting intermittent breakdown transient signals, early faults of electrical equipment can be diagnosed. Since there are multiple breakdown waveforms in the intermittent breakdown transient signal, it is difficult for time domain analysis to capture the full picture of the fault and it is impossible to directly extract fault characteristics from the time domain; and when using frequency domain waveforms for analysis, there are also multiple singular points, which makes it impossible for traditional Fourier frequency domain analysis methods to effectively extract and identify characteristic information related to the fault. Therefore, how to better deal with the complexity of intermittent breakdown transient signals and diagnose early faults of electrical equipment is a problem that needs to be solved urgently. Summary of the invention

[0003] The embodiments of the present invention provide an electrical equipment early fault diagnosis method, system, device and medium to solve the above technical problems in the prior art.

[0004] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0005] According to a first aspect of an embodiment of the present invention, a method for early fault diagnosis of electrical equipment is provided.

[0006] In one embodiment, the electrical equipment early fault diagnosis method includes:

[0007] Collect fault current signals of electrical equipment;

[0008] Performing multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale;

[0009] Reconstructing a frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal;

[0010] The differential extreme point is calculated for the obtained time domain signal to obtain the differential extreme point; and the first first-order differential extreme point that appears is taken as the time when the intermittent fault occurs.

[0011] In one embodiment, multi-scale time-frequency analysis is performed on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of various scales, including:

[0012] A plurality of scale components are obtained, and the fault current signal is decomposed in time and frequency based on each scale component to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale; wherein each scale component includes the highest frequency of the signal, the scale, and the signal acquisition frequency.

[0013] In one embodiment, the time-frequency decomposition formula is:

[0014]

[0015] In the formula, represents the frequency domain signal of the corresponding scale; ω represents the decomposed frequency band; is the Fourier decomposition of the signal f(t), For the nth iteration is the frequency domain signal of the i-th scale, is the Lagrange multiplier, α is the penalty factor, is the center frequency of scale L in the nth iteration, ω i is the center frequency of the i-th iteration, L is the scale number, and n is the number of iterations.

[0016] In one embodiment, reconstructing a frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal includes:

[0017] All high-frequency frequency domain signals are set to zero, all low-frequency frequency domain signals remain unchanged, and the frequency domain signals are reconstructed scale by scale to obtain the time domain signal.

[0018] In one embodiment, performing differential extreme point calculation on the obtained time domain signal to obtain the differential extreme point includes:

[0019] The reconstructed time domain signal is subjected to differential operation processing to obtain a differential operation result; and extreme value points are calculated based on the differential operation result to obtain differential extreme value points.

[0020] In one embodiment, the calculation formula for the differential operation processing is:

[0021] F'(n)=F(n)-F(n-1),n=1,2,3…N

[0022] In the formula, F'(n) is the discretization sequence of the first-order derivative of the state quantity, F(n) and F(n-1) are the nth and n-1th values ​​of the state quantity in the discretization sequence respectively; n and N refer to the discretization value and maximum value of the state quantity respectively.

[0023] In one embodiment, the extreme point calculation formula is:

[0024] F”(n k )st(F'(n k )-F'(n k -1))×(F'(n k )-F'(n k +1))>0 k=1,2,3…M

[0025] Where, F”(n k ) is the nth discrete sequence of the second-order derivative of the state quantity k Item; F'(n k )、F'(n k -1) are the nth order of the discretization sequence of the first-order derivative of the state quantity k 、n k -1 item; n k is the corresponding discrete serial number of the extreme point; k, M are the serial number and total number of extreme points respectively.

[0026] According to a second aspect of an embodiment of the present invention, a system for early fault diagnosis of electrical equipment is provided.

[0027] In one embodiment, the electrical equipment early fault diagnosis system comprises:

[0028] A fault signal acquisition module is used to acquire fault current signals of electrical equipment;

[0029] A multi-scale time-frequency analysis module, used to perform multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of various scales;

[0030] A frequency domain signal reconstruction module, used to reconstruct the frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal;

[0031] The fault time judgment module is used to calculate the differential extreme point of the obtained time domain signal to obtain the differential extreme point; and take the first-order differential extreme point that appears as the time when the intermittent fault occurs.

[0032] In one embodiment, when the multi-scale time-frequency analysis module performs multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale, it obtains multiple scale components, and performs time-frequency decomposition on the fault current signal based on each scale component to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale; wherein each scale component includes the highest frequency of the signal, the scale, and the signal acquisition frequency.

[0033] In one embodiment, the time-frequency decomposition formula is:

[0034]

[0035] In the formula, represents the frequency domain signal of the corresponding scale; ω represents the decomposed frequency band; is the Fourier decomposition of the signal f(t), For the nth iteration is the frequency domain signal of the i-th scale, is the Lagrange multiplier, α is the penalty factor, is the center frequency of scale L in the nth iteration, ω i is the center frequency of the i-th iteration, L is the scale number, and n is the number of iterations.

[0036] In one embodiment, when the frequency domain signal reconstruction module reconstructs the frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain the time domain signal, all high-frequency frequency domain signals are set to zero, all low-frequency frequency domain signals remain unchanged, and the frequency domain signal is reconstructed scale by scale to obtain the time domain signal.

[0037] In one embodiment, the fault time judgment module performs differential extreme point calculation on the obtained time domain signal to obtain the differential extreme point, performs differential operation processing on the reconstructed time domain signal to obtain the differential operation result; and performs extreme point calculation based on the differential operation result to obtain the differential extreme point.

[0038] In one embodiment, the calculation formula for the differential operation processing is:

[0039] F'(n)=F(n)-F(n-1),n=1,2,3…N

[0040] In the formula, F'(n) is the discretization sequence of the first-order derivative of the state quantity, F(n) and F(n-1) are the nth and n-1th values ​​of the state quantity in the discretization sequence respectively; n and N refer to the discretization value and maximum value of the state quantity respectively.

[0041] In one embodiment, the extreme point calculation formula is:

[0042] F”(n k )st(F'(n k )-F'(n k -1))×(F'(n k )-F'(n k +1))>0k=1,2,3…M

[0043] Where, F”(n k ) is the nth discrete sequence of the second-order derivative of the state quantityk Item; F'(n k )、F'(n k -1) are the nth order of the discretization sequence of the first-order derivative of the state quantity k 、n k -1 item; n k is the corresponding discrete serial number of the extreme point; k, M are the serial number and total number of extreme points respectively.

[0044] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0045] In one embodiment, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0046] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0047] In one embodiment, the computer-readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0048] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0049] The present invention performs time-frequency analysis on transient signals, retains characteristic frequency bands, and finally reconstructs them into time domain signals and extracts fault features, which can better cope with the complexity of intermittent breakdown transient signals, thereby improving the accuracy and reliability of electrical equipment fault diagnosis.

[0050] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0052] Figure 1 is a flow chart of a method for early fault diagnosis of electrical equipment according to an exemplary embodiment;

[0053] Figure 2 is a structural block diagram of an electrical equipment early fault diagnosis system according to an exemplary embodiment;

[0054] Figure 3 is a waveform diagram of an original signal according to an exemplary embodiment;

[0055] Figure 41 is a diagram showing high and low frequency signal waveforms and reconstructed waveforms at scale 1 according to an exemplary embodiment;

[0056] Figure 5 The figure is a schematic diagram showing the structure of a computer device according to an exemplary embodiment. DETAILED DESCRIPTION

[0057] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0058] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0059] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0060] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0061] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0062] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0063] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0064] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0065] Figure 1 An embodiment of an early fault diagnosis method for electrical equipment according to the present invention is shown.

[0066] In this optional embodiment, the electrical equipment early fault diagnosis method includes:

[0067] Step S101, collecting fault current signals of electrical equipment;

[0068] Step S103, performing multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of various scales;

[0069] Step S105, reconstructing a frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal;

[0070] Step S107, performing differential extreme value point calculation on the obtained time domain signal to obtain differential extreme value points; and taking the first-order differential extreme value point that appears as the intermittent fault occurrence time.

[0071] Figure 2 An embodiment of an early fault diagnosis system for electrical equipment according to the present invention is shown.

[0072] In this optional embodiment, the electrical equipment early fault diagnosis system includes:

[0073] A fault signal acquisition module 201 is used to acquire fault current signals of electrical equipment;

[0074] A multi-scale time-frequency analysis module 203 is used to perform multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of various scales;

[0075] A frequency domain signal reconstruction module 205 is used to reconstruct the frequency domain signal according to the high frequency frequency domain signal and the low frequency frequency domain signal to obtain a time domain signal;

[0076] The fault time judgment module 207 is used to perform differential extreme value point calculation on the obtained time domain signal to obtain differential extreme value points; and take the first-order differential extreme value point that appears as the intermittent fault occurrence time.

[0077] In specific applications, the collected fault current signal can be shown in Table 1, specifically as follows:

[0078] Table 1 shows the fault current signal sampling values

[0079]

[0080]

[0081] When performing multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale, multiple scale components can be obtained, and the fault current signal is decomposed in time and frequency based on each scale component to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale. Among them, each scale component includes the highest frequency of the signal, the scale, and the signal acquisition frequency; specifically: determine the highest frequency of the signal as f max , the signal sampling frequency is 2f max , the scale N is a positive integer, generally N = 5, and the scale components are: {f max , 1 / 2f max}; {1 / 2f max , 1 / 4f max}; {1 / 4f max , 1 / 8f max}; {1 / 8f max , 1 / 16f max}; {1 / 16f max , 1 / 32f max}.

[0082] The time-frequency decomposition formula is:

[0083]

[0084] In the formula, represents the frequency domain signal of the corresponding scale; ω represents the decomposed frequency band; is the Fourier decomposition of the signal f(t), For the nth iteration is the frequency domain signal of the i-th scale, is the Lagrange multiplier, α is the penalty factor, is the center frequency of scale L in the nth iteration, ω i is the center frequency of the i-th iteration, L is the scale number, and n is the number of iterations.

[0085] Specifically, the high-frequency and low-frequency frequency domain signals obtained by decomposition are V j and W j , for each scale, can be decomposed into: W ψ (V j )=V j+1 +W j+1 ,j∈Z; where W ψ (V j ) represents the signal V j Frequency domain decomposition, V j+1 is the high frequency part of the scale j signal, W j+1 is the low-frequency part of the scale j signal.

[0086] After N decompositions, the high-frequency parts are all set to zero, the low-frequency parts remain unchanged, and the time domain reconstruction algorithm is implemented scale by scale. Specifically, for scale N, the original frequency domain signal is:

[0087] W ψ (V N-1 )=V N +W N

[0088] The reconstructed frequency domain signal of scale N-1 is:

[0089] V N-1 =W ψ -1 (W N )

[0090] Where V N-1 represents the frequency domain signal of N-1 scale; V N represents the frequency domain signal of N scale; W ψ -1 represents the time domain reconstruction algorithm; WN Represents a low-frequency frequency domain signal of N scale.

[0091] Finally, the reconstructed time domain signal F(n) is:

[0092] F(n)=V0=(W ψ -1 …(W ψ -1 (W N )))

[0093] Where F(n) represents the reconstructed time domain signal; V0 represents the high frequency part of the scale 0 signal, which is the desired reconstructed signal, W N Represents a low-frequency frequency domain signal of N scale.

[0094] The scale N is a positive integer, which depends on the fault type and sampling rate. Generally, N=5. The waveforms of the high-frequency signal and low-frequency signal of the first scale after the original signal is decomposed are as follows: Figure 4 As shown in Table 2, the offset increases with the increase of the transformation scale. Since the reconstructed signal returns to the time domain, there is no offset and the noise is much smaller than the original signal. The reconstructed time domain signal is shown in Table 2.

[0095] Table 2 shows the reconstructed fault current signal

[0096]

[0097]

[0098] When differential extreme value points are calculated on the obtained time domain signal to obtain differential extreme value points, differential operation processing can be performed on the reconstructed time domain signal to obtain differential operation results; and extreme value point calculation is performed based on the differential operation results to obtain differential extreme value points.

[0099] The calculation formula for the differential operation is:

[0100] F'(n)=F(n)-F(n-1),n=1,2,3…N

[0101] In the formula, F'(n) is the discretization sequence of the first-order derivative of the state quantity, F(n) and F(n-1) are the nth and n-1th values ​​of the state quantity in the discretization sequence respectively; n and N refer to the discretization value and maximum value of the state quantity respectively.

[0102] The extreme point calculation formula is:

[0103] F”(n k )st(F'(n k )-F'(n k -1))×(F'(nk )-F'(n k +1))>0 k=1,2,3…M

[0104] Where, F”(n k ) is the nth discrete sequence of the second-order derivative of the state quantity k Item; F'(n k )、F'(n k -1) are the nth order of the discretization sequence of the first-order derivative of the state quantity k 、n k -1 item; n k is the corresponding discrete serial number of the extreme point; k, M are the serial number and total number of extreme points respectively.

[0105] Figure 5 An embodiment of a computer device of the present invention is shown. The computer device may be a server, and the computer device includes a processor, a memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0106] Those skilled in the art will understand that Figure 5 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0107] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0108] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0109] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0110] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for early fault diagnosis of electrical equipment, characterized in that: include: Collect fault current signals of electrical equipment; Performing multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale; Reconstructing a frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal; Perform differential extreme value point calculation on the obtained time domain signal to obtain differential extreme value points; The first first-order difference extreme point that appears is regarded as the occurrence time of the intermittent fault.

2. The method for early fault diagnosis of electrical equipment according to claim 1, characterized in that: The fault current signal is subjected to multi-scale time-frequency analysis to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of various scales, including: Acquire multiple scale components; and perform time-frequency decomposition on the fault current signal based on each scale component to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale; wherein each scale component includes the highest frequency of the signal, the scale, and the signal acquisition frequency.

3. The method for early fault diagnosis of electrical equipment according to claim 2, characterized in that: The formula for the time-frequency decomposition is: In the formula, represents the frequency domain signal of the corresponding scale; ω represents the decomposed frequency band; is the Fourier decomposition of the signal f(t), For the nth iteration is the frequency domain signal of the i-th scale, is the Lagrange multiplier, α is the penalty factor, is the center frequency of scale L in the nth iteration, ω i is the center frequency of the ith iteration, L is the scale number, and n is the number of iterations.

4. The method for early fault diagnosis of electrical equipment according to claim 1, characterized in that: Reconstructing the frequency domain signal according to the high frequency domain signal and the low frequency domain signal to obtain the time domain signal includes: All high-frequency frequency domain signals are set to zero, all low-frequency frequency domain signals remain unchanged, and the frequency domain signals are reconstructed scale by scale to obtain the time domain signal.

5. The method for early fault diagnosis of electrical equipment according to claim 1, characterized in that: The differential extreme points are calculated for the obtained time domain signal, and the obtained differential extreme points include: The reconstructed time domain signal is subjected to differential operation processing to obtain a differential operation result; and extreme value points are calculated based on the differential operation result to obtain differential extreme value points.

6. The method for early fault diagnosis of electrical equipment according to claim 5, characterized in that: The calculation formula for the differential operation processing is: F'(n)=F(n)-F(n-1),n=1,2,3…N In the formula, F'(n) is the discretization sequence of the first-order derivative of the state quantity, F(n) and F(n-1) are the nth and n-1th values ​​of the state quantity in the discretization sequence respectively; n and N refer to the discretization value and maximum value of the state quantity respectively.

7. The method for early fault diagnosis of electrical equipment according to claim 6, characterized in that: The extreme point calculation formula is: F”(n) k )st(F'(n k )-F'(n k -1))×(F'(n k )-F'(n k +1))>0k=1,2,3…M In the formula, F" (n k ) is the nth discrete sequence of the second-order derivative of the state quantity k Item; F'(n k )、F'(n k -1) are the nth order of the discretization sequence of the first-order derivative of the state quantity k 、n k -1 item; n k is the corresponding discrete serial number of the extreme point; k, M are the serial number and total number of extreme points respectively.

8. An early fault diagnosis system for electrical equipment, characterized in that: include: A fault signal acquisition module is used to acquire fault current signals of electrical equipment; A multi-scale time-frequency analysis module, used to perform multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of various scales; A frequency domain signal reconstruction module, used to reconstruct the frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain a time domain signal; A fault time judgment module is used to calculate the differential extreme value point of the obtained time domain signal to obtain the differential extreme value point; The first first-order difference extreme point that appears is regarded as the occurrence time of the intermittent fault.

9. The electrical equipment early fault diagnosis system according to claim 8, characterized in that: The multi-scale time-frequency analysis module obtains multiple scale components when performing multi-scale time-frequency analysis on the fault current signal to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale; The fault current signal is decomposed in time and frequency based on each scale component to obtain high-frequency frequency domain signals and low-frequency frequency domain signals of each scale; wherein each scale component includes the highest frequency of the signal, the scale and the signal acquisition frequency.

10. The electrical equipment early fault diagnosis system according to claim 9, characterized in that: The formula for the time-frequency decomposition is: In the formula, represents the frequency domain signal of the corresponding scale; ω represents the decomposed frequency band; is the Fourier decomposition of the signal f(t), For the nth iteration is the frequency domain signal of the i-th scale, is the Lagrange multiplier, α is the penalty factor, is the center frequency of scale L in the nth iteration, ω i is the center frequency of the i-th iteration, L is the scale number, and n is the number of iterations.

11. The electrical equipment early fault diagnosis system according to claim 8, characterized in that: When the frequency domain signal reconstruction module reconstructs the frequency domain signal according to the high-frequency frequency domain signal and the low-frequency frequency domain signal to obtain the time domain signal, all high-frequency frequency domain signals are set to zero, all low-frequency frequency domain signals remain unchanged, and the frequency domain signal is reconstructed scale by scale to obtain the time domain signal.

12. The electrical equipment early fault diagnosis system according to claim 8, characterized in that: The fault time judgment module performs differential extreme point calculation on the obtained time domain signal to obtain the differential extreme point, performs differential operation processing on the reconstructed time domain signal to obtain the differential operation result; and performs extreme point calculation based on the differential operation result to obtain the differential extreme point.

13. The electrical equipment early fault diagnosis system according to claim 12, characterized in that: The calculation formula for the differential operation processing is: F'(n)=F(n)-F(n-1),n=1,2,3…N In the formula, F'(n) is the discretization sequence of the first-order derivative of the state quantity, F(n) and F(n-1) are the nth and n-1th values ​​of the state quantity in the discretization sequence respectively; n and N refer to the discretization value and maximum value of the state quantity respectively.

14. The electrical equipment early fault diagnosis system according to claim 13, characterized in that: The extreme point calculation formula is: F”(n k )s.t.(F'(n k )-F'(n k -1))×(F'(n k )-F'(n k +1))>0 k=1,2,3…M In the formula, F" (n k ) is the nth discrete sequence of the second-order derivative of the state quantity k Item; F'(n k )、F'(n k -1) are the nth order of the discretization sequence of the first-order derivative of the state quantity k 、n k -1 item; n k is the corresponding discrete serial number of the extreme point; k, M are the serial number and total number of extreme points respectively.

15. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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