Three-phase common-box GIL vibration state detection method and device based on optical fiber sensing

Abstract

The invention discloses a three-phase common-box GIL vibration state detection method and device based on optical fiber sensing, and belongs to the technical field of high voltage and insulation, and the method comprises the steps: 1, uniformly winding one end of an optical fiber on the surface of a to-be-detected three-phase common-box GIL, and selecting a pulse signal generator according to the characteristic frequency of a to-be-detected signal, transmitting a pulse detection optical signal to an optical fiber wound on the surface of the GIL; 2, collecting a Rayleigh scattering light signal containing the GIL vibration signal under the action of the pulse detection light signal, and converting the Rayleigh scattering light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal; and step 3, debugging and de-noising the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common-box GIL. According to the invention, the change of the GIL vibration signal is reflected by using the scattered light signal in the optical fiber, and the device can be applied to the on-line monitoring of the insulation defect and partial discharge in the three-phase common-box GIL equipment by replacing the pulse signal generator.

Description

Technical Field

[0001] The present invention belongs to the technical field of high voltage and insulation, and in particular relates to a method and a device for detecting the vibration state of a three-phase common box GIL based on optical fiber sensing. Background Art

[0002] As a new type of power transmission method, gas insulated metal-enclosed transmission line (GIL) has the advantages of large transmission capacity, low loss, high reliability and long life. Through reasonable planning and design, it can reduce the project cost and improve the reliability of the system. Among them, three-phase common box GIL has broad application prospects in urban transmission and distribution networks due to its advantages of small space occupation and low civil construction cost.

[0003] Although GIL is considered to be maintenance-free or even maintenance-free, some defects may be left behind during the manufacturing, transportation, installation, maintenance and operation, such as metal burrs on the conductor, loose or poor contact of components, air gaps formed by the separation of the conductor and the supporting insulator, residues after maintenance, and metal particles in the cavity. These defects will gradually deteriorate during long-term operation, and when they reach a certain level, partial discharge (PD) will occur inside the GIL device. Partial discharge will accelerate the further damage to the insulation inside the GIL device, eventually leading to power outages caused by insulation failures, which seriously threatens the safe and stable operation of the power grid.

[0004] Since the GIL equipment adopts a closed modular structure, the existing detection methods are difficult to accurately locate the specific faulty components and the degree of defects, and power outage maintenance of the GIL will bring great economic losses and high costs. Therefore, it is urgent to propose a method and device that can detect partial discharge inside the GIL from the outside of the GIL. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for detecting the vibration characteristics of a three-phase common box GIL based on optical fiber sensing. By testing the Rayleigh scattered light signal on the surface of the three-phase common box GIL, the vibration state of the three-phase common box GIL is determined, laying the foundation for online monitoring of internal insulation defects and partial discharge of the three-phase common box GIL equipment.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions.

[0007] The first aspect of the present invention provides a method for detecting vibration state of a three-phase common box GIL based on optical fiber sensing, the method comprising:

[0008] Step 1, evenly wind one end of the optical fiber on the surface of the three-phase common box GIL to be tested, select different pulse signal generators according to the characteristic frequency of the signal to be tested, and emit a pulse detection light signal to the optical fiber wound on the surface of the GIL;

[0009] Step 2, collecting the Rayleigh scattered light signal containing the GIL vibration signal under the action of the pulse detection light signal, and converting the Rayleigh scattered light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal;

[0010] Step 3: debug and denoise the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

[0011] Preferably, in step 1, transmitting a pulse detection signal further comprises:

[0012] Select a narrow line width light source to emit a continuous laser signal, couple the continuous laser signal and output a high energy laser signal and a low energy laser signal respectively, wherein the high energy laser signal is used as a detection light signal and the low energy laser signal is used as a reference light signal;

[0013] The detection light signal is modulated into a pulse detection light signal of specified pulse width and period according to the pulse signal of specified pulse width and period, and then the pulse detection light signal is enhanced and processed, and the processed pulse detection light signal is sent to the optical fiber wrapped around the surface of the GIL through the optical fiber.

[0014] Preferably, in step 2, converting the Rayleigh scattered light signal including the GIL vibration signal into a waveform signal including the GIL vibration signal further comprises:

[0015] Under the action of the pulse detection light signal, the Rayleigh scattered light signal containing the GIL vibration signal is collected, and the scattered light signal is coupled with the reference light signal and then converted into a waveform signal containing the GIL vibration signal.

[0016] Preferably, in step 3, denoising the waveform signal includes decomposing the non-stationary signal into intrinsic mode functions by EMD decomposition, and the specific decomposition process is:

[0017] Step 3.1, find all the maximum and minimum points of the original signal X(t) to form the upper and lower envelopes, and the average of the two envelopes is m 1 , find X(t) and m 1 The difference:

[0018] X(t)-m 1 =h 1

[0019] Where h 1 is the initially extracted modality;

[0020] Step 3.2, determine h 1 Is it an intrinsic mode function? If so, then h 1 is considered as the first intrinsic mode function; if not, h 1 As the signal to be decomposed X(t), repeat step 3.1 until h 1 Satisfies the intrinsic mode function condition and is recorded as the first intrinsic mode function IMFc 1 ; In this process, the program is terminated by controlling the standard deviation SD:

[0021]

[0022] In the above formula, h 1(k-1) (t) and h 1k (t) are h 1 The SD of the components obtained by repeating step 3.1 for the k-1th and kth times is usually between 0.2 and 0.3;

[0023] Step 3.3, subtract c from the original input signal X(t) 1 , and obtain the residual signal r 1 :

[0024] X(t)-c1=r1

[0025] Where c 1 is the first intrinsic mode function IMFc 1 ;

[0026] Step 3.4, r 1 As X(t), repeat steps 3.1 to 3.3 to continuously update the IMF c2 , IMF c3 ...IMF cn and the residual signal r n :

[0027] r 1 -c 2 =r 2 , ..., r n-1 -c n =r n

[0028] Step 3.5, when c n or n When it is less than the threshold, or when r n When monotonic, the decomposition is complete, and n intrinsic mode function components and one residual component r are obtained. n :

[0029]

[0030] Step 3.6, extract the useful intrinsic mode function components and subtract the useless high-frequency random noise; distinguish the useful signal from the random noise by calculating the correlation coefficient between the decomposed intrinsic mode function and the original noisy signal; the correlation coefficient can be obtained by the following formula:

[0031]

[0032] In the above formula, cov(c i ,X) represents each intrinsic mode function component c i The covariance with the original signal X, σ is the standard deviation; set a suitable correlation coefficient threshold, classify the intrinsic mode functions with correlation coefficients higher than the threshold as useful signal components, and classify the intrinsic mode functions with correlation coefficients lower than the threshold as noise components;

[0033] Step 3.7, the natural mode function components of the useful signal are added together to obtain the final noise-cancelled signal, which is a signal reflecting the vibration state of the three-phase common box GIL.

[0034] The second aspect of the present invention provides a three-phase co-box GIL vibration state detection device based on optical fiber sensing, which is used to implement the above-mentioned three-phase co-box GIL vibration state detection method based on optical fiber sensing, and the device includes a light source signal transmission module, a scattered light signal acquisition module, a waveform signal processing module, an optical fiber, a circulator and a signal line;

[0035] One end of the optical fiber is evenly wound on the wall surface of the three-phase common box GIL tube, and the other end of the optical fiber is connected to the circulator, and is respectively connected to the light source signal transmitting module and the scattered light signal collecting module through the circulator; the light source signal transmitting module is connected to the scattered light signal collecting module through the optical fiber, and the scattered light signal collecting module is connected to the waveform signal processing module through the signal line;

[0036] The light source signal transmitting module is used to transmit a specified pulse detection light signal to the optical fiber on the surface of the GIL tube wall;

[0037] The scattered light signal acquisition module is used to acquire the scattered light signal including the GIL vibration signal and convert it into a waveform signal including the GIL vibration signal;

[0038] The waveform signal processing module is used to debug and denoise the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

[0039] Preferably, the light source signal transmission module includes a narrow linewidth light source, a 1:99 coupler, an acousto-optic modulator, a pulse signal generator and an Er-doped fiber amplifier;

[0040] The narrow linewidth light source is connected to a 1:99 coupler via an optical fiber, a high energy output port in the 1:99 coupler is connected to an acousto-optic modulator via an optical fiber, a low energy output port is connected to a scattered light signal acquisition module via an optical fiber, a pulse signal generator is connected to the acousto-optic modulator via a signal line, the acousto-optic modulator is connected to an Er-doped fiber amplifier via an optical fiber, and the Er-doped fiber amplifier is connected to the surface of a three-phase common box GIL via an optical fiber through a circulator.

[0041] Preferably, the narrow linewidth light source sends a continuous laser signal to a 1:99 coupler, and the 1:99 coupler couples the continuous laser signal and outputs a high-energy laser signal and a low-energy laser signal respectively, wherein the high-energy laser signal is sent to the acousto-optic modulator through an optical fiber as a detection light signal, and the low-energy laser signal is sent to the 2:2 coupler in the signal acquisition module through an optical fiber as a reference light signal;

[0042] The pulse signal generator sends a pulse signal of a specified pulse width and period to the acousto-optic modulator through a signal line. The acousto-optic modulator modulates the detection light signal into a pulse detection light signal of a specified pulse width and period according to the received pulse signal, and then outputs the pulse detection light signal to the Er-doped fiber amplifier.

[0043] The Er-doped fiber amplifier enhances the pulse detection light signal and sends the processed pulse detection light signal to the optical fiber wound on the surface of the GIL through the optical fiber.

[0044] Preferably, the pulse signal generator is a replaceable module, and a pulse signal generator with different pulse widths and pulse frequencies is selected according to the characteristic frequency of the signal to be measured.

[0045] Preferably, the scattered light signal acquisition module includes a 2:2 coupler and a balanced light detector, the 2:2 coupler and the balanced light detector are connected through an optical fiber, the 2:2 coupler is also connected to the low energy output port of the 1:99 coupler through an optical fiber, and is connected to the optical fiber on the surface of the three-phase co-box GIL through a circulator;

[0046] The 2:2 coupler is used to receive the Rayleigh scattered light signal including the GIL vibration signal, and couple the scattered light signal with the reference light signal and send them to the balanced light detector respectively;

[0047] The balanced light detector is used to convert the coupled Rayleigh scattered light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal, and output the waveform signal to the waveform signal processing module.

[0048] Preferably, the waveform signal processing module includes an oscilloscope and a PC-side processor, wherein the oscilloscope is connected to the balanced light detector in the scattered light signal acquisition module and the PC-side processor respectively through a signal line;

[0049] The oscilloscope is used to receive and debug the waveform signal output by the balanced light detector, and transmit the debugged waveform signal to the PC processor through the signal line;

[0050] The PC-side processor is used to perform denoising on the received waveform signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

[0051] Compared with the prior art, the beneficial effects of the present invention include:

[0052] The light source signal transmitting module, scattered light signal collecting module, waveform signal processing module and optical fiber of the present invention form a complete three-phase common box GIL vibration signal testing device. Based on the optical fiber sensing technology, the sensing optical fiber is directly arranged on the surface of the three-phase common box GIL, and the scattered light signal in the optical fiber is used to reflect the change of the vibration signal. The operation is simple and the cost is lower. By testing the Rayleigh scattered light signal on the surface of the three-phase common box GIL, the vibration state of the three-phase common box GIL surface is determined, which lays a foundation for the online monitoring of internal insulation defects and partial discharge of the three-phase common box GIL equipment.

[0053] The sample positioning test device of the present invention is a selective detachable structure, which selects pulse signal generators with different pulse widths and pulse frequencies according to the characteristic frequencies of different test objects, such as human damage factors (1-5Hz), three-phase common box GIL core vibration (100Hz) and higher frequency partial discharge signals. It lays a foundation for realizing online monitoring of internal insulation defects and partial discharge in three-phase common box GIL. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the structure of the vibration characteristic detection device of the three-phase common box GIL of the present invention;

[0055] Figure 2 yes Figure 1 The structural diagram of the light source signal transmission module;

[0056] Figure 3 yes Figure 1 Schematic diagram of the structure of the scattered light signal acquisition module;

[0057] Figure 4 yes Figure 1 Schematic diagram of the structure of the waveform signal processing module.

[0058] Figure numerals: three-phase common box GIL pipe wall 1, three-phase common box GIL three-phase conductor 2, optical fiber 3, three-port circulator 4, vibration state detection device 5, light source signal transmission module 51, narrow linewidth light source 511, 1:99 coupler 512, acousto-optic modulator 513, pulse signal generator 514, Er-doped fiber amplifier 515, scattered light signal acquisition module 52, 2:2 coupler 521, balanced light detector 522, waveform signal processing module 53, oscilloscope 531, PC-side processor 532, signal line 6. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] Under the action of electric force, the center core of the three-phase GIL in a common box will vibrate continuously and weakly, and the insulation defects and partial discharge inside the GIL can cause the instantaneous vibration of the surface of the three-phase GIL to change. Through optical fiber sensing, high-density vibration signal measurement of up to hundreds of kilometers can be achieved. Therefore, based on optical fiber sensing, by testing the characteristic signal of Rayleigh scattered light on the surface of the GIL, the vibration state information of the three-phase GIL in a common box can be obtained, and then the partial discharge detection inside the three-phase GIL in a common box can be realized. Therefore, the development of a vibration state detection method and device for the three-phase GIL in a common box based on optical fiber sensing technology can lay the foundation for the location of insulation defects and partial discharge monitoring of the three-phase GIL in a common box.

[0061] Embodiment 1, a method for detecting vibration state of a three-phase common box GIL based on optical fiber sensing, comprises the following steps:

[0062] Step 1, transmitting light source signal: before the test, the optical fiber is evenly wound on the surface of the three-phase common box GIL tube wall, ensuring that all components and modules are connected well, and different pulse signal generators are selected according to the characteristic frequency of the signal to be tested, and the pulse detection light signal is transmitted to the optical fiber wound on the surface of the GIL;

[0063] In a further preferred but non-limiting embodiment, in step 1, transmitting a pulse detection signal further comprises:

[0064] Select a narrow line width light source to emit a continuous laser signal, couple the continuous laser signal and output a high energy laser signal and a low energy laser signal respectively, wherein the high energy laser signal is used as a detection light signal and the low energy laser signal is used as a reference light signal;

[0065] The detection light signal is modulated into a pulse detection light signal of specified pulse width and period according to the pulse signal of specified pulse width and period, and then the pulse detection light signal is enhanced and processed, and the processed pulse detection light signal is sent to the optical fiber wrapped around the surface of the GIL through the optical fiber.

[0066] Step 2, the optical fiber wound around the surface of the GIL collects the Rayleigh scattered light signal containing the GIL vibration signal under the action of the pulse detection light signal, and converts the Rayleigh scattered light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal;

[0067] In a further preferred but non-limiting embodiment, in step 2, converting the Rayleigh scattered light signal containing the GIL vibration state information into a waveform signal containing the GIL vibration information further comprises:

[0068] The optical fiber wound on the surface of the GIL collects the Rayleigh scattered light signal containing the GIL vibration information under the action of the pulse detection light signal, and converts the scattered light signal into a waveform signal containing the GIL vibration information after coupling with the reference light signal.

[0069] Step 3: debug and denoise the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

[0070] In a further preferred but non-limiting embodiment, in step 3, denoising the waveform signal includes decomposing the non-stationary signal into intrinsic mode functions by an EMD decomposition method, and the specific decomposition process is:

[0071] 1) Find all the maximum and minimum points of the original signal X(t) to form the upper and lower envelopes. The average of the two envelopes is m 1 , find X(t) and m 1 The difference:

[0072] X(t)-m 1 =h 1

[0073] Where h 1 is the initially extracted modality;

[0074] 2) Determine h 1 Is it an intrinsic mode function? If so, then h 1 is considered as the first intrinsic mode function; if not, h 1 As the signal to be decomposed X(t), repeat the process 1) until h 1 Satisfies the intrinsic mode function condition and is recorded as the first intrinsic mode function IMFc 1 In this process, the program is terminated by controlling the standard deviation SD:

[0075]

[0076] In the above formula, h 1(k-1) (t) and h 1k (t) are h 1 The SD of the components obtained by repeating step 1) for the k-1th and kth times is usually between 0.2 and 0.3.

[0077] 3) Subtract c from the original input signal X(t) 1 , and obtain the residual signal r 1 :

[0078] X(t)-c1=r1

[0079] Where c 1 is the first intrinsic mode function IMFc 1 ;

[0080] 4) r 1 As X(t), repeat the process 1) to 3) to continuously update the IMF c2 , IMF c3 ...IMF cn and the residual signal r n :

[0081] r 1 -c 2 =r 2 , ..., r n-1 -c n =r n

[0082] 5) When c n or n When it is less than the threshold, or when r n When monotonic, the decomposition is complete, and n intrinsic mode function components and one residual component r are obtained. n :

[0083]

[0084] To achieve signal denoising, it is necessary to extract the useful intrinsic mode function components and subtract the useless high-frequency random noise. The useful signal and random noise can be distinguished by calculating the correlation coefficient between the decomposed intrinsic mode function and the original noisy signal. The correlation coefficient can be obtained by the following formula:

[0085]

[0086] In the above formula, cov(c i ,X) represents each intrinsic mode function component c i The covariance with the original signal X, σ is the standard deviation.

[0087] Furthermore, a suitable correlation coefficient threshold is set, and the intrinsic mode functions with correlation coefficients higher than the threshold are classified as useful signal components; the intrinsic mode functions with correlation coefficients lower than the threshold are classified as noise components. The useful signal intrinsic mode function components are added together to obtain the final denoised signal, which is the signal reflecting the surface vibration state of the three-phase common box GIL.

[0088] Embodiment 2, a three-phase common box GIL vibration state detection device based on optical fiber sensing, is used to implement the three-phase common box GIL vibration state detection method based on optical fiber sensing described in embodiment 1. Figure 1 As shown, the device comprises: a three-phase common box GIL tube wall 1, a three-phase common box GIL three-phase conductor 2, an optical fiber 3, a three-port circulator 4, a vibration state detection device 5 and a signal line 6;

[0089] One end of the optical fiber 3 is evenly wound on the surface of the three-phase common box GIL pipe wall 1, and the other end of the optical fiber 3 is connected to the three-port circulator 4, and is connected to the vibration state detection device 5 through the three-port circulator 4;

[0090] The vibration state detection device 5 includes: a light source signal transmitting module 51, a scattered light signal acquisition module 52 and a waveform signal processing module 53; wherein the optical fiber 3 is connected to the light source signal transmitting module 51 and the scattered light signal acquisition module 52 respectively through a three-port circulator 4; the light source signal transmitting module 51 is connected to the scattered light signal acquisition module 52 through the optical fiber 3, and the scattered light signal acquisition module 52 is connected to the waveform signal processing module 53 through the signal line 6.

[0091] like Figure 2 As shown, the light source signal transmitting module 51 includes: a narrow linewidth light source 511, a 1:99 coupler 512, an acousto-optic modulator 513, a pulse signal generator 514 and an Er-doped fiber amplifier 515, the narrow linewidth light source 511 is connected to the 1:99 coupler 512 through the optical fiber 3, the high energy output port in the 1:99 coupler 512 is connected to the acousto-optic modulator 513 through the optical fiber 3, the low energy output port is connected to the 2:2 coupler 521 in the signal acquisition module 52 through the optical fiber 3, the pulse signal generator 514 is connected to the acousto-optic modulator 513 through the signal line 6, the acousto-optic modulator 513 is connected to the Er-doped fiber amplifier 515 through the optical fiber 3, and the Er-doped fiber amplifier 515 is connected to the surface of the three-phase common box GIL pipe wall 1 through the optical fiber 3 and the three-port circulator 4;

[0092] In a further preferred but non-limiting embodiment, the pulse signal generator 514 in the light source signal transmitting module 51 is a replaceable module, and a pulse signal generator with different pulse widths and pulse frequencies is selected according to the characteristic frequency of the signal to be measured;

[0093] In one embodiment, for the three-phase common box GIL core vibration with a characteristic frequency of 100 Hz caused by electromotive force, a pulse signal generator with a pulse width of 200 nm and a pulse frequency of 100 kHz is selected.

[0094] like Figure 3 As shown, the scattered light signal acquisition module 52 includes a 2:2 coupler 521 and a balanced light detector 522, wherein the 2:2 coupler 521 is connected to the low energy output port of the 1:99 coupler 512 in the light source signal transmission module 51 through the optical fiber 3, receives the reference light signal output by the low energy output port of the 1:99 coupler 512, and is connected to the optical fiber 3 wound on the surface of the three-phase common box GIL pipe wall 1 through the optical fiber 3 via the three-port circulator 4, receives the scattered light signal containing the three-phase common box GIL vibration signal, the 2:2 coupler 521 balances the reference light signal with the scattered light signal and transmits it to the balanced light detector 522 through the optical fiber 3, obtains the waveform signal containing the three-phase common box GIL vibration signal, and the balanced light detector 522 transmits the waveform signal to the oscilloscope 531 in the waveform signal processing module 53 through the signal line 6;

[0095] like Figure 4 As shown, the waveform signal processing module 53 includes an oscilloscope 531 and a PC-side processor 532. The oscilloscope 531 is used to receive and debug the waveform signal from the balanced light detector 522 in the scattered light signal acquisition module 52, and transmit the debugged waveform signal to the PC-side processor 532 through the signal line 6. The PC-side processor 532 denoises the received waveform signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

[0096] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting vibration state of a three-phase co-enclosure GIL based on optical fiber sensing, characterized in that: The method includes: Step 1, evenly wind one end of the optical fiber on the surface of the three-phase common box GIL to be tested, select different pulse signal generators according to the characteristic frequency of the signal to be tested, and emit a pulse detection light signal to the optical fiber wound on the surface of the GIL; Step 2, collecting the Rayleigh scattered light signal containing the GIL vibration signal under the action of the pulse detection light signal, and converting the Rayleigh scattered light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal; Step 3: debug and denoise the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

2. The method for detecting vibration state of a three-phase co-enclosure GIL based on optical fiber sensing according to claim 1, characterized in that: In the step 1, transmitting the pulse detection signal also includes: Select a narrow line width light source to emit a continuous laser signal, couple the continuous laser signal and output a high energy laser signal and a low energy laser signal respectively, wherein the high energy laser signal is used as a detection light signal and the low energy laser signal is used as a reference light signal; The detection light signal is modulated into a pulse detection light signal of specified pulse width and period according to the pulse signal of specified pulse width and period, and then the pulse detection light signal is enhanced and processed, and the processed pulse detection light signal is sent to the optical fiber wrapped around the surface of the GIL through the optical fiber.

3. The method for detecting vibration state of a three-phase co-enclosure GIL based on optical fiber sensing according to claim 1, characterized in that: In step 2, converting the Rayleigh scattered light signal including the GIL vibration signal into a waveform signal including the GIL vibration signal further includes: Under the action of the pulse detection light signal, the Rayleigh scattered light signal containing the GIL vibration signal is collected, and the scattered light signal is coupled with the reference light signal and then converted into a waveform signal containing the GIL vibration signal.

4. The method for detecting vibration state of a three-phase co-enclosure GIL based on optical fiber sensing according to claim 1, characterized in that: In step 3, the denoising process of the waveform signal includes decomposing the non-stationary signal into intrinsic mode functions by EMD decomposition. The specific decomposition process is as follows: Step 3.1, find all the maximum and minimum points of the original signal X(t), form the upper and lower envelopes, the average of the two envelopes is m1, and find the difference between X(t) and m1: X(t)-m1=h1 Where h1 is the initially extracted mode; Step 3.2, determine whether h1 is an intrinsic mode function. If so, h1 is regarded as the first intrinsic mode function; if not, h1 is regarded as the signal to be decomposed X(t), and the process of step 3.1 is repeated until h1 meets the intrinsic mode function condition, and it is recorded as the first intrinsic mode function IMFc1; in this process, the program is terminated by controlling the standard deviation SD: In the above formula, h 1(k-1) (t) and h 1k (t) are the components obtained by repetition of step 3.1 for the k-1th and kth times of h1, and the SD is usually between 0.2 and 0.3; Step 3.3, subtract c1 from the input original signal X(t) to get the residual signal r1: X(t)-c1=r1 Where c1 is the first intrinsic mode function IMFc1; Step 3.4: Take r1 as X(t) and repeat steps 3.1 to 3.3 to continuously update the IMF. c2 , IMF c3 ...IMF cn and the residual signal r n : r1-c2=r2,...,r n-1 -c n =r n Step 3.5, when c n or n When it is less than the threshold, or when r n When monotonic, the decomposition is complete, and n intrinsic mode function components and one residual component r are obtained. n : Step 3.6, extract the useful intrinsic mode function components and subtract the useless high-frequency random noise; distinguish the useful signal from the random noise by calculating the correlation coefficient between the decomposed intrinsic mode function and the original noisy signal; the correlation coefficient can be obtained by the following formula: In the above formula, cov(c i ,X) represents each intrinsic mode function component c i The covariance with the original signal X, σ is the standard deviation; set a suitable correlation coefficient threshold, classify the intrinsic mode functions with correlation coefficients higher than the threshold as useful signal components, and classify the intrinsic mode functions with correlation coefficients lower than the threshold as noise components; Step 3.7, the natural mode function components of the useful signal are added together to obtain the final noise-cancelled signal, which is a signal reflecting the vibration state of the three-phase common box GIL.

5. A three-phase co-enclosure GIL vibration state detection device based on optical fiber sensing, used to implement a three-phase co-enclosure GIL vibration state detection method based on optical fiber sensing as claimed in any one of claims 1 to 4, characterized in that: The device comprises a light source signal transmitting module, a scattered light signal collecting module, a waveform signal processing module, an optical fiber, a circulator and a signal line; One end of the optical fiber is evenly wound on the wall surface of the three-phase common box GIL tube, and the other end of the optical fiber is connected to the circulator, and is respectively connected to the light source signal transmitting module and the scattered light signal collecting module through the circulator; the light source signal transmitting module is connected to the scattered light signal collecting module through the optical fiber, and the scattered light signal collecting module is connected to the waveform signal processing module through the signal line; The light source signal transmitting module is used to transmit a specified pulse detection light signal to the optical fiber on the surface of the GIL tube wall; The scattered light signal acquisition module is used to acquire the scattered light signal including the GIL vibration signal and convert it into a waveform signal including the GIL vibration signal; The waveform signal processing module is used to debug and denoise the waveform signal containing the GIL vibration signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

6. The three-phase common box GIL vibration state detection device based on optical fiber sensing according to claim 5 is characterized by: The light source signal transmission module includes a narrow line width light source, a 1:99 coupler, an acousto-optic modulator, a pulse signal generator and an Er-doped fiber amplifier; The narrow linewidth light source is connected to a 1:99 coupler via an optical fiber, a high energy output port in the 1:99 coupler is connected to an acousto-optic modulator via an optical fiber, a low energy output port is connected to a scattered light signal acquisition module via an optical fiber, a pulse signal generator is connected to the acousto-optic modulator via a signal line, the acousto-optic modulator is connected to an Er-doped fiber amplifier via an optical fiber, and the Er-doped fiber amplifier is connected to the surface of a three-phase common box GIL via an optical fiber through a circulator.

7. The three-phase common box GIL vibration state detection device based on optical fiber sensing according to claim 6 is characterized by: The narrow linewidth light source sends a continuous laser signal to a 1:99 coupler, and the 1:99 coupler couples the continuous laser signal and outputs a high-energy laser signal and a low-energy laser signal respectively, wherein the high-energy laser signal is sent to an acousto-optic modulator through an optical fiber as a detection light signal, and the low-energy laser signal is sent to a 2:2 coupler in a signal acquisition module through an optical fiber as a reference light signal; The pulse signal generator sends a pulse signal of a specified pulse width and period to the acousto-optic modulator through a signal line. The acousto-optic modulator modulates the detection light signal into a pulse detection light signal of a specified pulse width and period according to the received pulse signal, and then outputs the pulse detection light signal to the Er-doped fiber amplifier. The Er-doped fiber amplifier enhances the pulse detection light signal and sends the processed pulse detection light signal to the optical fiber wound on the surface of the GIL through the optical fiber.

8. The three-phase common box GIL vibration state detection device based on optical fiber sensing according to claim 7 is characterized in that: The pulse signal generator is a replaceable module, and a pulse signal generator with different pulse widths and pulse frequencies is selected according to the characteristic frequency of the signal to be measured.

9. A three-phase co-enclosure GIL vibration state detection device based on optical fiber sensing according to any one of claims 5 to 7, characterized in that: The scattered light signal acquisition module includes a 2:2 coupler and a balanced light detector, the 2:2 coupler and the balanced light detector are connected through an optical fiber, the 2:2 coupler is also connected to the low energy output port of the 1:99 coupler through an optical fiber, and is connected to the optical fiber on the surface of the three-phase co-box GIL through a circulator; The 2:2 coupler is used to receive the Rayleigh scattered light signal containing the GIL vibration information, and couple the scattered light signal with the reference light signal and send them to the balanced light detector respectively; The balanced light detector is used to convert the coupled Rayleigh scattered light signal containing the GIL vibration signal into a waveform signal containing the GIL vibration signal, and output the waveform signal to the waveform signal processing module.

10. The three-phase common box GIL vibration state detection device based on optical fiber sensing according to claim 5, characterized in that: The waveform signal processing module includes an oscilloscope and a PC-side processor, wherein the oscilloscope is connected to the balanced light detector in the scattered light signal acquisition module and the PC-side processor respectively through a signal line; The oscilloscope is used to receive and debug the waveform signal output by the balanced light detector, and transmit the debugged waveform signal to the PC processor through the signal line; The PC-side processor is used to perform denoising on the received waveform signal to obtain a signal reflecting the vibration state of the three-phase common box GIL.

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