A method and device for detecting partial discharge faults based on optical microdisks

Abstract

The application relates to a partial discharge fault detection method and device based on an optical microdisk, and belongs to the technical field of fault detection. The method comprises the following steps: emitting a laser signal; adjusting the laser signal intensity to obtain an adaptive laser signal; coupling the optical signal of a specific wavelength in the adaptive laser signal to form a stable standing wave and obtain a first optical signal; converting the first optical signal into an electric signal, and performing phase-sensitive demodulation on the electric signal to obtain position information of the acoustic signal; and identifying and positioning the partial discharge signal according to the position information. The application realizes real-time online detection, significantly improves the detection efficiency, has electromagnetic interference resistance, reduces the dependence on a large amount of information processing, and shortens the data processing time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fault detection, in particular to a partial discharge fault detection method and device based on an optical microdisk. BACKGROUND

[0002] Distribution transformers are critical equipment in power distribution systems, and their stable operation is essential for ensuring the reliability of power supply and the safety of the power grid. Once a transformer fails, it not only threatens the safety of the power grid, but also can cause huge economic losses. Currently, many transformers have reached or are close to their expected service life, but due to the lack of effective monitoring means, potential defects of these aging transformers often cannot be discovered in time, thereby increasing the risk of accidents.

[0003] In order to prevent such accidents from occurring, it is particularly necessary to monitor the operating condition of the transformer in real time and carry out predictive maintenance. Existing transformer detection technologies include pulse current method and ultra-high frequency detection method. Although the pulse current method is simple in principle, it is an offline detection method and is not suitable for real-time monitoring, and is easily affected by electromagnetic interference. The ultra-high frequency detection method can achieve high-sensitivity online monitoring and defect positioning, but it has the problems of excessive information quantity, long data processing time and low detection efficiency in actual application. In view of this, the existing methods have certain limitations in actual application and cannot fully meet the demand for comprehensive and efficient monitoring of transformers. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to overcome the problems of real-time online detection, susceptibility to electromagnetic interference, excessive information quantity, long data processing time and low detection efficiency in the prior art.

[0005] In order to solve the above technical problems, the present application provides a partial discharge fault detection method based on an optical microdisk, comprising:

[0006] emitting a laser signal;

[0007] adjusting the intensity of the laser signal to obtain an adapted laser signal;

[0008] coupling the light signal of a specific wavelength in the adapted laser signal to form a standing wave that exists stably and obtain a first light signal;

[0009] converting the first light signal into an electrical signal and performing phase-sensitive demodulation on the electrical signal to obtain position information of the acoustic signal; and identifying and positioning the partial discharge signal according to the position information.

[0010] In one embodiment of the present application, the method for coupling the light signal of specific wavelength in the adaptive laser signal is whisper gallery mode, the whisper gallery mode includes coupling by using a transfer matrix, and the expression of the transfer matrix is:

[0011]

[0012] wherein b0, b1 and b2 are the output port light energy of different mode light, a0, a1 and a2 are the input port light energy of different mode light, t0, t1 and t2 are the transfer coefficients between different modes, j, k1, k2 and k c are the coupling coefficients between different modes.

[0013] In one embodiment of the present application, there is a phase shift between the coupling of the straight waveguide and the ring waveguide in the coupling process of the light signal of specific wavelength in the adaptive laser signal, and the range of the value of the phase shift changes the resonance amplitude value.

[0014] In one embodiment of the present application, when the range of the value of the phase shift is (2m-0.5)π<θ<(2m+0.5)π, the mathematical expression of the resonance amplitude value is:

[0015]

[0016] wherein θ is the phase shift, m is a positive integer, π is a circular constant, j and k c are the coupling coefficients between different modes, t1 and t2 are the transfer coefficients between different modes, b1 and b2 are the output port light energy of different mode light, α1 and α2 are the losses of the micro-disk resonator, and are the phase shifts of different whisper gallery modes.

[0017] In one embodiment of the present application, when the range of the value of the phase shift is (2m+0.5)π<θ<(2m+1)π, the mathematical expression of the resonance amplitude value is:

[0018]

[0019] wherein θ is the phase shift, m is a positive integer, π is a circular constant, j and k c are the coupling coefficients between different modes, t1 and t2 are the transfer coefficients between different modes, b1 and b2 are the output port light energy of different mode light, α1 and α2 are the losses of the micro-disk resonator, and are the phase shifts of different whisper gallery modes.

[0020] In one embodiment of the present application, the calculation formula of the phase shift of different whisper gallery modes is:

[0021]

[0022] wherein, is the phase shift of the ith whispering gallery mode, i is a positive integer greater than zero, π is the ratio of a circle, R is the radius of the micro-disk resonator, n eff_i is the effective refractive index corresponding to the ith whispering gallery mode, and λ is the wavelength in vacuum.

[0023] In an embodiment of the present application, the laser signal is a narrow linewidth laser signal.

[0024] In a second aspect, to solve the above technical problems, the present application provides a partial discharge fault detection device based on an optical micro-disk, comprising:

[0025] a tunable laser for emitting a laser signal;

[0026] an attenuator connected to the tunable laser by a multimode optical fiber, for adjusting the intensity of the laser signal to obtain an adapted laser signal;

[0027] at least one micro-disk resonator connected to the attenuator by an optical fiber, for coupling the optical signal of a specific wavelength in the adapted laser signal to form a stable standing wave and obtain a first optical signal;

[0028] a photodetector connected to the at least one micro-disk resonator by a single-mode optical fiber, for converting the first optical signal into an electrical signal;

[0029] a signal acquisition module directly connected to the photodetector, for phase-sensitive demodulation of the electrical signal to obtain the position information of the acoustic signal.

[0030] In an embodiment of the present application, each micro-disk resonator comprises a straight waveguide and a polymer cladding.

[0031] In an embodiment of the present application, a plurality of micro-disk resonators are distributed at equal intervals on the front and side surfaces of the transformer to form a micro-disk resonator array.

[0032] The above technical solution of the present application has the following beneficial effects compared with the prior art:

[0033] (1) The local discharge fault detection method and device based on optical micro-disk provided by the application utilize the instant response characteristics of laser signals to realize real-time online monitoring of local discharge signals, so as to quickly identify and prevent potential equipment faults. In particular, the application performs well in electromagnetic interference-sensitive environments and shows excellent environmental adaptability. By precisely coupling optical signals of specific wavelengths to form stable standing waves, the method ensures the stability and reliability of signal processing. In addition, the application can quickly complete the detection task, greatly reducing the waiting time and avoiding the need to process a large amount of information, thereby effectively improving work efficiency. Further, by converting laser signals into electrical signals and performing demodulation operations, the application can accurately locate the position of acoustic signals, thereby realizing accurate identification and positioning of local discharge signals.

[0034] (2) The micro-disk resonator provided by the application uses a polymer material as a substrate to replace the original silicon substrate to form a full-polymer waveguide micro-disk resonator, eliminating the problem of resonance wavelength drift. The device has the advantages of good electromagnetic compatibility, good insulation level, high acoustic sensitivity, wide frequency response, and high durability compared to traditional piezoelectric ceramic hydrophones. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in conjunction with the drawings, in which

[0036] Figure 1 A flowchart of a local discharge fault detection method based on an optical micro-disk in a preferred embodiment of the application;

[0037] Figure 2 A schematic diagram of a micro-disk resonator in a preferred embodiment of the application;

[0038] Figure 3 A structural diagram of a local discharge fault detection device based on an optical micro-disk in a preferred embodiment of the application;

[0039] Figure 4 A transmission curve diagram of a micro-disk resonator in a preferred embodiment of the application;

[0040] Figure 5 A cross-sectional view of a micro-disk resonator in a preferred embodiment of the application.

[0041] The drawing numbers in the specification are as follows: 1, tunable laser; 2, attenuator; 3, micro-disk resonator; 4, photodetector; 5, signal acquisition module; 6, straight waveguide; 7, polymer cladding. DETAILED DESCRIPTION

[0042] The application will be further described below with reference to the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it, but the embodiments are not limiting to the application.

[0043] Embodiment one

[0044] Referring to Figure 1 As shown in the figure, the embodiment of the application provides a partial discharge fault detection method based on an optical micro-disk, which comprises:

[0045] Emitting a laser signal;

[0046] Adjusting the intensity of the laser signal to obtain an adapted laser signal;

[0047] Coupling the light signal of a specific wavelength in the adapted laser signal to form a stable standing wave and obtain a first optical signal;

[0048] Converting the first optical signal into an electrical signal and performing phase-sensitive demodulation on the electrical signal to obtain the position information of the acoustic signal;

[0049] According to the position information, identifying and positioning the partial discharge signal.

[0050] The embodiment of the application provides a partial discharge fault detection method based on an optical micro-disk, which utilizes the rapid response capability of the laser signal to realize real-time online monitoring of the partial discharge signal, effectively prevents and quickly identifies potential equipment faults, and has electromagnetic interference resistance. By coupling the light signal of a specific wavelength to form a stable standing wave, the high stability and reliability of signal processing are ensured. The embodiment of the application can quickly perform detection tasks, significantly shorten the waiting time, avoid the need to process a large amount of information, and effectively improve the work efficiency. In addition, by converting the laser signal into an electrical signal and performing demodulation operation, the method can accurately capture the position information of the acoustic signal, realize accurate identification and positioning of the partial discharge signal, and fully and efficiently meet the needs of transformer monitoring.

[0051] Specifically, the method for coupling the light signal of a specific wavelength in the adapted laser signal is whispering gallery mode. Whispering gallery mode refers to the multiple reflections of light waves on the inner surface of an optical micro-resonator (such as a microsphere or a micro-disk), forming a special resonance mode. From the perspective of the micro-disk resonator, this mode can be divided into two types: an external whispering gallery mode outside the disk (mode 1) and an internal whispering gallery mode inside the disk (mode 2). In this embodiment, the two modes work together to form a 3x3 coupler. As shown in the figure, Figure 2 The coupling process of the whispering gallery mode involves using a transfer matrix to realize effective coupling of light waves. The expression of the transfer matrix is:

[0052]

[0053] wherein b0, b1 and b2 are output port optical energies of different mode lights, a0, a1 and a2 are input port optical energies of different mode lights, t0, t1 and t2 are transmission coefficients between different modes, j, k1, k2 and k c are coupling coefficients between different modes.

[0054] Further, there is a phase shift θ between the straight waveguide and the ring waveguide in the coupling process of the light signal of a specific wavelength in the adaptive laser signal, and the calculation formula is

[0055] θ = 2π 2 Rn eff / λ (2)

[0056] wherein π is a circular constant, R is the radius of the micro-disk resonator, n eff is the effective refractive index corresponding to the whisper gallery mode, and λ is the wavelength in vacuum.

[0057] Further, the resonance amplitude of the micro-disk resonator will be affected by different phase shift values, which means that the change range of the phase shift will directly change the resonance response of the resonator. In the embodiment, when the value range of the phase shift θ is (2m-0.5)π < θ < (2m+0.5)π, the mathematical expression of the resonance amplitude is:

[0058]

[0059] When the value range of the phase shift is (2m+0.5)π < θ < (2m+1)π, the mathematical expression of the resonance amplitude is:

[0060]

[0061] wherein θ is the phase shift, m is a positive integer, j and k c are coupling coefficients between different modes, t1 and t2 are transmission coefficients between different modes, b1 and b2 are output port optical energies of different mode lights, a1 and a2 are losses of the micro-disk resonator, and are phase shifts of different whisper gallery modes.

[0062] Further, the calculation formula of the phase shift of different whisper gallery modes is:

[0063]

[0064] wherein, is the phase shift of the i-th whisper gallery mode, i is a positive integer greater than zero, and in the example, the value of i is 1 or 2; n eff_iLet λ be the effective refractive index corresponding to the i-th whispering corridor mode, and λ be the wavelength in vacuum.

[0065] In practical applications, high-Q microdisk resonators exhibit improved transmission characteristics and phase shift near the resonant point. It is extremely sensitive, and this sensitivity is related to the refractive index n of the medium. eff_i Closely related. Because subtle changes caused by waveguide deformation are significantly amplified in high-Q microdisk resonators, the sensitivity to sound pressure is greatly improved. This means that even minute environmental changes, such as pressure changes caused by sound waves, can be effectively detected by the microdisk resonator.

[0066] Furthermore, when the straight waveguide is coupled to the disk guide of the microdisk resonator, equations (3) and (4) can be simplified to:

[0067]

[0068] Among them, S t Here, t0 is the transmission function, a0 and b0 are the mode optical energies at the input and output ports of the straight waveguide, and t0 is the transmission coefficient, specifically representing the transmission loss from the straight waveguide to the microdisk.

[0069] In this embodiment, the whispering corridor mode is used to couple optical signals of a specific wavelength from the adapted laser signal. This effectively confines the optical signal of that specific wavelength within the microdisk resonator, achieving efficient energy storage and enhanced resonance of the optical wave. This coupling method not only improves the signal quality and intensity but also greatly enhances the sensitivity to optical signals due to the high Q factor of the whispering corridor mode.

[0070] Specifically, phase-sensitive demodulation is performed on the electrical signal. The phase-sensitive demodulation steps include rectification and detection, phase-sensitive detection, and matched filtering. The filtered signal can reflect the acoustic signal information. In this embodiment, the phase-sensitive demodulation method is not limited and can be selected according to the actual application requirements.

[0071] Example 2

[0072] Based on the same inventive concept, this embodiment provides a partial discharge fault detection device based on an optical microdisk. The principle of solving the problem is similar to that of the partial discharge fault detection method based on an optical microdisk provided in Embodiment 1, and the repeated parts will not be described again.

[0073] Reference Figure 3 This embodiment provides a partial discharge fault detection device based on an optical microdisk, comprising:

[0074] Tunable laser 1 is used to emit laser signals;

[0075] An attenuator 2 is connected to the tunable laser 1 via a multimode optical fiber, used to adjust the intensity of the laser signal to obtain an adapted laser signal;

[0076] At least one micro-disk resonator 3 is connected to the attenuator 2 via an optical fiber, used to couple the light signal of a specific wavelength in the adapted laser signal to form a standing wave that exists stably and obtain a first optical signal;

[0077] A photodetector 4 is connected to the at least one micro-disk resonator 3 via a single-mode optical fiber, used to convert the first optical signal into an electrical signal;

[0078] A signal acquisition module 5 is directly connected to the photodetector 4, used to perform phase-sensitive demodulation on the electrical signal to obtain the position information of the acoustic signal.

[0079] The embodiment realizes real-time online detection of the device partial discharge signal through the tunable laser 1, the attenuator 2, the micro-disk resonator 3, the photodetector 4 and the signal acquisition module 5. The connection of the tunable laser 1 and the attenuator 2 can accurately control the intensity and wavelength of the emitted laser signal to adapt to different detection requirements. The signal acquisition module 5 is directly connected to the photodetector 4, reducing the delay in the signal transmission process and speeding up the data processing speed. In addition, the connection of the optical fiber reduces electromagnetic interference and improves the stability and reliability of signal transmission.

[0080] Specifically, the embodiment adopts narrow linewidth laser signals. Due to their excellent coherence, high spectral purity, system stability and long coherence length, such signals play a crucial role in multiple key fields such as optical interference, optical communication, precision measurement and quantum technology. In addition, narrow linewidth laser signals also have strong anti-electromagnetic interference ability and support remote control function, which enables them to maintain high performance and precise operation even in complex and variable environments. Therefore, in the embodiment, the tunable laser 1 is configured to emit narrow linewidth laser signals, and the wavelength scanning range is set between 1.5 microns and 1.6 microns to optimize the coupling efficiency with the micro-disk resonator 3. The transmission characteristics of the micro-disk resonator 3 are as shown in Figure 4 .

[0081] Specifically, the attenuator 2 adjusts the intensity of the laser signal through a multimode optical fiber connected to the tunable laser 1, thereby obtaining an adapted laser signal. This process involves precise program-controlled adjustments, and the attenuator 2 can change the loss of the optical signal in the transmission path to achieve flexible control of the optical intensity. The multimode optical fiber is particularly suitable for the transmission of high-power optical signals due to its ability to transmit multiple modes of optical signals. In this way, the attenuator 2 can adapt to the specific needs of laser signal intensity in different application scenarios, ensuring optimal performance of the optical signal in subsequent optical sensing and signal processing applications. In this embodiment, the laser signal intensity transmitted by the attenuator 2 is adapted to the micro-disk resonator 3.

[0082] During the operation of the distribution transformer, the acoustic signals generated by partial discharge have specific spectral characteristics, with frequencies mainly concentrated between 20 kHz and 400 kHz. In the medium of transformer oil, the corresponding wavelengths of these acoustic signals are approximately between 7.5 centimeters and 3.75 millimeters. There is a linear relationship between the sound pressure level of partial discharge and the discharge quantity, which is crucial for monitoring and diagnosing the health of the transformer. In order to accurately capture these acoustic signals, the micro-disk resonator 3 needs to have high sensitivity, wide dynamic range, and excellent signal-to-noise ratio. These performance parameters ensure that the micro-disk resonator 3 can effectively detect the weak acoustic waves generated by partial discharge and convert them into analyzable electrical signals. In transformer oil, the working principle of the micro-disk resonator 3 is mainly based on the physical effect of sound pressure. When acoustic waves propagate through the transformer oil, they cause slight deformation of the micro-disk resonator 3, a phenomenon known as sound pressure-induced deformation. At the same time, acoustic waves also cause photoelastic changes in the material, known as the photoelastic effect. In polystyrene, this photoelastic effect is particularly significant, allowing the micro-disk resonator 3 to reflect the presence and intensity of acoustic waves through changes in optical signals.

[0083] Specifically, in the actual operating environment (large temperature difference operation) of the distribution transformer, when the micro-disk resonator 3 is placed inside the distribution transformer, it is susceptible to resonance wavelength drift caused by operating temperature. The micro-disk resonator 3 uses a polymer material as a substrate instead of the original silicon substrate to form a full-polymer waveguide micro-disk resonator 3, eliminating the problem of resonance wavelength drift. Referring to Figure 5 , the micro-disk resonator 3 includes a straight waveguide 6 and a polymer cladding layer 7, which is used to isolate the sensor from the transformer oil and avoid the influence of the transformer oil on the sensor structure to improve the signal-to-noise ratio of the system. The device described in this embodiment uses electron beam lithography and nanoimprint technology, which can reduce the manufacturing cost of the micro-disk resonator 3.

[0084] Further, for the material of the micro-disk resonator 3, it can include polystyrene, a silica insulation layer, and a polymer cladding layer 7. Compared with traditional piezoelectric ceramic hydrophones, it has the advantages of good electromagnetic compatibility, high insulation level, high acoustic sensitivity, wide frequency response, and high durability. The micro-disk resonator 3 has practical significance for use in large temperature variation scenarios. This enables the present application to be widely applicable to the partial discharge phenomenon identification and positioning of various types of transformers, and can be used in actual production to prevent turn-to-turn short circuit and strand-to-strand short circuit accidents caused by insulation deterioration, and to avoid transformer explosion accidents caused by insulation defects.

[0085] In particular, the micro-disk resonator 3 has flexible installation options and can be built-in or external to the transformer. These micro-disk resonators 3 form an array (which can be referred to as a micro-disk resonator array) that is placed on an insulating material to ensure a safe distance from the transformer winding and oil tank wall, avoiding electromagnetic interference. The micro-disk resonator array is arranged in an equidistant manner on the front and side of the transformer, forming an effective acoustic wave receiving network. In this embodiment, 3-6 micro-disk resonators 3 are arranged equidistantly on the front, and 3-6 micro-disk resonators 3 are arranged equidistantly on the side, to maximize the capture of direct stress wave signals generated by internal partial discharge events in the transformer. Through this designed array, the sensitivity and coverage of signal reception can be significantly improved, thereby realizing real-time monitoring and accurate diagnosis of the transformer state. This innovative arrangement not only enhances the reliability of the detection device, but also provides strong support for transformer maintenance and fault prevention.

[0086] Further, when the encapsulated micro-disk resonator 3 is fixed inside the transformer oil tank, a high-frequency acoustic signal of 20 kHz to 400 kHz is generated when a partial discharge phenomenon occurs inside the distribution transformer. The time interval and position information of the distributed micro-disk resonator array acting on the stress wave generated by receiving the acoustic signal can locate the position information of the partial discharge without artifacts.

[0087] In the device provided in this embodiment, the signal acquisition module 5 also includes a host computer. When the electrical signal processed by the photodetector 4 is directly transmitted to the signal acquisition module 5, the host computer collects and processes it. This design ensures the accuracy and real-time nature of the data, improving the efficiency and reliability of signal acquisition.

[0088] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer readable program code.

[0089] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0090] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0092] Obviously, the above-described embodiments are only examples and are not intended to limit the present application. Other variations and modifications can be made to the above-described embodiments without departing from the scope of the present application. The scope of the present application is not limited to the above-described embodiments and should be determined by the appended claims.

Claims

1. A partial discharge fault detection method based on optical microdisk, characterized in that, The method comprises the following steps: emitting a laser signal; wherein the laser signal is a narrow linewidth laser signal; adjusting the intensity of the laser signal to obtain an adapted laser signal suitable for an optical micro-disk; The whispering gallery mode is used to couple the light signal of a specific wavelength in the adaptive laser signal to form a stable standing wave and obtain a first light signal; wherein, during the coupling of the light signal of the specific wavelength in the adaptive laser signal, there is a phase shift between the straight waveguide and the ring waveguide, and different value ranges of the phase shift change the resonance amplitude value; the value range of the phase shift is When the value range of the phase shift is 0.5-1.5, the mathematical expression of the resonance amplitude value is: ； wherein, is the phase shift, is a positive integer, is the ratio of the circumference of a circle to its diameter, and is the coupling coefficient between different modes, and is the transmission coefficient between different modes, and is the output port optical energy of different modes of light, and is the loss of the micro-disk resonator, and is the phase shift of different whisper gallery modes; the phase shift is in the range of when the mathematical expression of the resonance amplitude is: ； converting the first optical signal into an electrical signal, and performing phase-sensitive demodulation on the electrical signal to obtain position information of the acoustic signal; and identifying and locating the partial discharge signal according to the position information.

2. The partial discharge fault detection method based on optical microcavity according to claim 1, characterized in that, The whisper gallery mode comprises coupling by using a transfer matrix, and the expression of the transfer matrix is: ； wherein, , and are the output port optical energies for different mode lights, , and are the input port optical energies for different mode lights, , and are the transmission coefficients between different modes, , , and are the coupling coefficients between different modes.

3. The method according to claim 1, wherein, The calculation formula of the phase shift of the different whisper gallery modes is: ； wherein, is the phase shift for the th whispering gallery mode, is a positive integer greater than zero, is the ratio of the circumference of a circle to its diameter, is the radius of the microdisk resonator, is the phase shift for the th whispering gallery mode, is the wavelength in vacuum.

4. An optical micro-disk based partial discharge fault detection device for implementing the optical micro-disk based partial discharge fault detection method of any one of claims 1 to 3, characterized in that, The method comprises the following steps: a tunable laser for emitting a laser signal; an attenuator connected to the tunable laser by using a multimode optical fiber, for adjusting the intensity of the laser signal to obtain an adapted laser signal; at least one micro-disk resonator connected to the attenuator by using an optical fiber, for coupling an optical signal of a specific wavelength in the adapted laser signal to form a stable standing wave and obtain a first optical signal; a photodetector connected to the at least one micro-disk resonator by using a single-mode optical fiber, for converting the first optical signal into an electrical signal; a signal acquisition module directly connected to the photodetector, for performing phase-sensitive demodulation on the electrical signal to obtain position information of the acoustic signal.

5. The optical microcavity-based partial discharge fault detection device of claim 4, wherein, Each of the micro-disk resonators comprises a straight waveguide and a polymer cladding.

6. The optical microcavity-based partial discharge fault detection device of claim 4, wherein, A plurality of the micro-disk resonators are distributed at equal intervals on the front and side surfaces of the transformer to form a micro-disk resonator array.

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