Partial discharge location method and device for measuring ultrasonic signals based on optical fiber sensing

Abstract

The present application discloses a method and device for partial discharge localization based on optical fiber sensing to measure ultrasonic signals. The solution provided by the present application is based on the ultrasonic signals obtained by an optical fiber sensing measurement system. By performing a Hilbert transform on the output signal of the optical fiber sensing measurement system, that is, the amplitude of the Rayleigh backscattering spectrum curve group, and extracting its envelope, the modulation information of the ultrasonic signals is obtained. Then, through differential processing, the modulation effect on the disturbance signals is revealed. Based on the time interval when the peaks appear in the signal curve group after differential processing, combined with the speed of light and the equivalent group velocity in the optical fiber, and the triggering time of the pulse signal, the specific location of the disturbance is determined, realizing partial discharge localization based on optical fiber sensing to measure ultrasonic signals.

Description

Technical Field

[0001] The present application relates to the technical field of high voltage and insulation, and particularly to a method and device for local discharge positioning based on fiber optic sensing to measure ultrasonic signals. Background Art

[0002] In a power system, the operating states of various high-voltage electrical equipment directly determine the safety and stability of the entire system. Partial discharge in power cables is the main cause of long-term deterioration of the insulation medium of high-voltage electrical equipment, and even breakdown, fire accidents, or permanent damage to the equipment. For a long time, the detection of partial discharge in power cables is of great significance for the normal operation and fault prediction of high-voltage equipment. In recent years, with the rapid development of many new technologies in the industry, Φ-OTDR fiber optic sensing measurement is one of them. Compared with traditional measurement technologies, fiber optic sensing measurement technology has good insulation performance and is not easily affected by electromagnetic interference, and has good application prospects in the field of partial discharge measurement.

[0003] At present, fiber optic sensing measurement technology has been widely used in scenarios such as measuring strain, temperature, and disturbance. However, its application in measuring ultrasonic signals of partial discharge in power equipment is still under research. Therefore, how to further extract useful information from the measured ultrasonic signals to achieve local discharge positioning based on fiber optic sensing measurement of ultrasonic signals has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] The present application provides a method and device for local discharge positioning based on fiber optic sensing to measure ultrasonic signals, for achieving the invention purpose of local discharge positioning based on fiber optic sensing to measure ultrasonic signals.

[0005] To achieve the above invention purpose, the first aspect of the present application provides a method for local discharge positioning based on fiber optic sensing to measure ultrasonic signals, including:

[0006] Obtaining ultrasonic signals measured by fiber optic sensing;

[0007] Performing waveform segmentation on the ultrasonic signals, and performing Hilbert transform on each segmented waveform signal to obtain the amplitude of the waveform signal;

[0008] Based on the amplitudes of the respective waveform signals, extracting the envelope of the ultrasonic signals to obtain a first curve group;

[0009] Performing difference processing on the first curve group to obtain a difference curve group;

[0010] Based on the time intervals where peaks appear in the difference curve group, combining the speed of light and the equivalent group velocity in the optical fiber, and the pulse signal trigger time, determining the disturbance positioning interval.

[0011] Preferably, determining the disturbance positioning interval based on the time interval when the peak value appears in the differential curve group, in combination with the light speed and equivalent group velocity in the optical fiber and the pulse signal triggering time, specifically includes:

[0012] Based on the time interval when the peak value appears in the differential curve group, subtract the pulse signal triggering time from the time interval, then multiply by the light speed and equivalent group velocity in the optical fiber, and then determine the disturbance positioning interval according to half of the calculated product result.

[0013] Preferably, it further includes:

[0014] Based on the time point when the peak value appears in the differential curve group, determine the amplitude value at this time point of the first curve group as the reference amplitude value. Based on the reference amplitude value, recombine each of the waveform signals to obtain the vibration waveform signal of the external disturbance, and perform FFT transformation on the vibration waveform signal to obtain the main frequency of the vibration waveform signal, so as to facilitate judging whether the ultrasonic signal is generated by partial discharge according to the main frequency.

[0015] Preferably, the waveform segmentation of the ultrasonic signal specifically includes:

[0016] According to the pulse signal in the trigger waveform of the fiber optic sensing measurement system, segment the ultrasonic signal at equal intervals according to the trigger period of the pulse signal.

[0017] Preferably, before performing differential processing on the first curve group to obtain a differential curve group, it further includes:

[0018] Perform white noise elimination processing on the first curve group to obtain the processed first curve group.

[0019] Meanwhile, a second aspect of the present application provides a partial discharge positioning device for ultrasonic signals based on fiber optic sensing, including:

[0020] A signal acquisition unit, configured to acquire ultrasonic signals obtained through fiber optic sensing measurement;

[0021] A waveform segmentation unit, which performs waveform segmentation on the ultrasonic signal and performs Hilbert transform on each of the segmented waveform signals to obtain the amplitude value of the waveform signal;

[0022] A first curve group extraction unit, configured to extract the envelope line of the ultrasonic signal based on the amplitude values of each of the waveform signals to obtain a first curve group;

[0023] A differential processing unit, configured to perform differential processing on the first curve group to obtain a differential curve group;

[0024] A positioning unit, configured to determine a disturbance positioning interval based on the time interval in which peaks appear in the differential curve group, in combination with the speed of light and the equivalent group velocity in the optical fiber and the triggering time of the pulse signal.

[0025] Preferably, the positioning unit is specifically configured to:

[0026] Based on the time interval in which peaks appear in the differential curve group, subtract the triggering time of the pulse signal from the time interval, then multiply the result by the speed of light and the equivalent group velocity in the optical fiber, and then determine the disturbance positioning interval according to half of the calculated product result.

[0027] Preferably, it further includes:

[0028] A waveform main frequency extraction unit, configured to, based on the time points at which peaks appear in the differential curve group, determine the reference amplitude of the first curve group at the time points, and based on the reference amplitude, recombine each of the waveform signals to obtain a vibration waveform signal of the external disturbance, and perform an FFT transform on the vibration waveform signal to obtain the main frequency of the vibration waveform signal, so as to facilitate determining whether the ultrasonic signal is generated by partial discharge according to the main frequency.

[0029] Preferably, the waveform segmentation unit is specifically configured to:

[0030] According to the pulse signal in the triggering waveform of the fiber optic sensing measurement system, segment the ultrasonic signal at equal intervals according to the triggering period of the pulse signal, and perform Hilbert transform on each of the segmented waveform signals to obtain the amplitude of the waveform signal.

[0031] Preferably, it further includes:

[0032] A white noise elimination unit, configured to perform white noise elimination processing on the first curve group to obtain a processed first curve group.

[0033] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0034] The method provided by the present application is based on the ultrasonic signal obtained by the fiber optic sensing measurement system. By performing Hilbert transform on the output signal of the fiber optic sensing measurement system, that is, the amplitude of the Rayleigh backscattering spectrum curve group, and extracting its envelope, the ultrasonic signal modulation information is obtained. Then, through differential processing, the modulation effect on the disturbance signal is manifested, and based on the time interval in which peaks appear in the signal curve group after differential processing, in combination with the speed of light and the equivalent group velocity in the optical fiber and the triggering time of the pulse signal, the specific position of the disturbance is determined, realizing the partial discharge positioning of the ultrasonic signal based on fiber optic sensing. Description of the Drawings

[0035] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a schematic flowchart of an embodiment of a partial discharge location method based on fiber optic sensing for measuring ultrasonic signals provided by the present application.

[0037] Figure 2 It is a schematic flowchart of another embodiment of a partial discharge location method based on fiber optic sensing for measuring ultrasonic signals provided by the present application.

[0038] Figure 3 It is a calculation flowchart for obtaining the amplitude A(t) of the ultrasonic signal s(t) by using Hilbert transform in a partial discharge location method based on fiber optic sensing for measuring ultrasonic signals provided by the present application. p (t).

[0039] Figure 4 It is a time-domain waveform diagram of the Φ-OTDR ultrasonic signal within a single pulse period.

[0040] Figure 5 It is a waveform diagram of a differential curve group obtained by a partial discharge location method based on fiber optic sensing for measuring ultrasonic signals provided by the present application.

[0041] Figure 6 It is a reconstructed ultrasonic signal waveform diagram at the short-axis time of 5.210 μs.

[0042] Figure 7 It is a reconstructed ultrasonic signal FFT spectrum diagram at the short-axis time of 5.210 μs.

[0043] Figure 8 It is a schematic structural diagram of an embodiment of a partial discharge location device based on fiber optic sensing for measuring ultrasonic signals provided by the present application. Detailed implementation manners

[0044] The embodiments of the present application provide a partial discharge location method and device based on fiber optic sensing for measuring ultrasonic signals, which are used to further extract useful information from the measured ultrasonic signals and achieve the invention purpose of partial discharge location based on fiber optic sensing for measuring ultrasonic signals.

[0045] To make the invention objectives, features, and advantages of this application more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the embodiments described below are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0046] Please refer to Figure 1 , a partial discharge location method based on fiber optic sensing for measuring ultrasonic signals provided by the first embodiment of this application includes:

[0047] Step 101, obtain the ultrasonic signal measured by fiber optic sensing.

[0048] Step 102, perform waveform segmentation on the ultrasonic signal, and perform Hilbert transform on each segmented waveform signal to obtain the amplitude of the waveform signal.

[0049] It should be noted that based on the ultrasonic signal obtained in step 101, through the waveform segmentation processing method, the ultrasonic signal is segmented into N segments of waveform signals. Then, perform Hilbert transform on the N waveform signals obtained after segmentation, and the amplitude of each waveform signal can be obtained after the transform.

[0050] Step 103, based on the amplitude of each waveform signal, extract the envelope of the ultrasonic signal to obtain the first curve group.

[0051] Then, based on the amplitude of each waveform signal in the ultrasonic signal obtained by Hilbert transform, and then through the envelope extraction method, extract the envelope of the ultrasonic signal. The extracted envelope is the first curve group r mentioned in this embodiment i (i = 1, 2,..., N).

[0052] Step 104, perform differential processing on the first curve group to obtain a differential curve group.

[0053] It should be noted that in this embodiment, the differential processing of the first curve group is to show the relative change of the ultrasonic signal s(t) converted from the Rayleigh backscattered light signal to obtain the partial discharge ultrasonic modulation signal. The fiber optic Rayleigh backscattered light is modulated by an external vibration signal to form a dynamic fluctuation. Because the vibration amplitudes at different times are different, the modulation intensity of the scattered light is also different. After successive differential processing, this modulation process is shown. The specific method is to perform differential calculation on the above first curve group in sequence to obtain a new differential curve group.

[0054] Step 105: Based on the time interval when the peaks appear in the differential curve group, in combination with the speed of light in the optical fiber, the equivalent group velocity, and the pulse signal triggering time, determine the disturbance positioning interval.

[0055] Next, according to the differential curve group obtained in Step 104, determine the time interval [t1, t2] on the short-axis time axis where the peak of the differential curve group is located. Then, in combination with the speed of light in the optical fiber and the equivalent group velocity v g and the pulse signal triggering time Δt, determine the disturbance positioning interval [z1, z2]. Here, z1 and z2 in the disturbance positioning interval refer to the lengths of the optical fiber measured from the entrance of the optical fiber for the incident light. Therefore, the disturbance positioning interval [z1, z2] can represent the disturbance signal source, that is, the position of the partial discharge is within the section from z1 to z2 away from the entrance of the optical fiber.

[0056] The above content is the detailed description of the first embodiment of a partial discharge positioning method based on optical fiber sensing for measuring ultrasonic signals provided by this application. The following is the detailed description of the second embodiment of a partial discharge positioning method based on optical fiber sensing for measuring ultrasonic signals provided by this application.

[0057] Please refer to Figure 2 , based on the content disclosed in the above first embodiment, a partial discharge positioning method based on optical fiber sensing for measuring ultrasonic signals provided by the second embodiment of this application includes:

[0058] Further, Step 102 mentioned in the above first embodiment specifically includes the following steps:

[0059] According to the pulse signal in the trigger waveform of the optical fiber sensing measurement system, the ultrasonic signals are segmented at equal intervals according to the trigger period of the pulse signal, and Hilbert transform is performed on each segmented waveform signal to obtain the amplitude of the waveform signal.

[0060] It should be noted that in this embodiment, the trigger waveform of the Φ-OTDR system is used to segment the detected signal waveform at equal intervals according to the trigger period of the pulse signal, so that each obtained waveform is the complete Rayleigh backscattering spectrum curve of each trigger signal on the optical fiber segment. Subsequently, Hilbert transform is used to obtain the amplitude of the output signal of the Φ-OTDR system, that is, the Rayleigh backscattering spectrum curve, and extract its envelope line to obtain the modulation information of the partial discharge ultrasonic signal loaded on the Rayleigh scattering spectrum curve. The specific principle is as follows:

[0061] The Φ-OTDR system converts the Rayleigh backscattered optical signal into an electrical signal through a photodetector, and its voltage signal expression is:

[0062]

[0063] Wherein, G is the voltage gain, with the unit of V / A; is the optoelectronic conversion coefficient of the photodiode, with the unit of A / W; and are the powers of Rayleigh backscattered light and local oscillator reference light respectively; ω IF = ω c - ω LO = 2πΔf IF is the difference frequency between the signal light and the reference light, where Δf IF is the intermediate frequency; φ s , φ LO are the phases of Rayleigh backscattered light and local oscillator reference light.

[0064] The phase shift function φ p (t L ) changes the output signal s(t) of the Φ-OTDR system simultaneously through amplitude modulation and phase modulation. Write the expression of the output signal s(t) in a form containing the amplitude modulation term A p (t) and the phase modulation term φ p (t):

[0065] s(t) = A p (t)cos[ω IF t + φ IF + φ p (t)]

[0066] Wherein, φ IF = φ s - φ LO represents the phase difference without ultrasonic disturbance; the amplitude modulation term is the modulation function in the presence of external ultrasonic disturbance, and it is implicitly related to the ultrasonic signal; the newly added phase modulation term φ p (t) can be written as the ultrasonic phase offset function corresponding to equi-periodic pulse sampling:

[0067]

[0068] Wherein, t L = t + nT p is the conversion relationship between the long-axis time (the disturbance time of ultrasonic waves to the optical fiber) t L and the short-axis time (the transmission time of a single pulsed light in the optical fiber starting from the optical fiber entrance) t; T p is the sampling period of ultrasonic waves; n = 1, 2,..., N. is the integer quotient of t L modulo T p , representing the sequence number of the sequence signal s (n) (t), that is, the sampling point sequence number of the ultrasonic disturbance.

[0069] The detection signal s(t) of each pulsed light is rewritten according to the sampling sequence number n as follows:

[0070]

[0071] In the formula, the amplitude modulation term and the phase modulation term become the explicit forms associated with the discrete sampling sequence n of the ultrasonic signal.

[0072] Using Hilbert Transform (HT) digital signal processing to analyze the amplitude modulation term (n) (t) and the phase modulation term from the detection sequence signal s is signal demodulation.

[0073] Since the detection signal s (n) (t) of the Φ-OTDR system itself has the characteristics of a random waveform, and the phase modulation signal corresponding to the partial discharge ultrasonic disturbance only modulates a certain part (near t = t0) of the s (n) (t) signal, causing different amplitude phase offsets of s (n) (t) near t = t0. Therefore, performing an incremental transformation on the s (n) (t) signal helps to discover the ultrasonic phase modulation signal acting locally Perform the transformation according to the following formula:

[0074] s (n) (t) = s 0 (t) - Δs (n) (t)

[0075]

[0076]

[0077] In the formula, s 0 (t) represents the output signal of the Φ-OTDR system without ultrasonic disturbance or at a certain initial moment of ultrasonic disturbance, and Δs (n) (t) represents the incremental signal of s L = t + nT p obtained at the subsequent time t (n) (t) with respect to s 0 (t); decompose φ IF in the formula into φ0 + φ n , where φ0 is the phase delay of the Rayleigh backscattered light itself that is independent of ultrasonic disturbance at t = t0, and φ n is the phase noise introduced by the laser.

[0078] Δs (n) (t) The incremental signal remains ω IF The modulation signal of the frequency band, which contains and More complex modulation forms, but further presenting the ultrasonic phase modulation function In its amplitude modulation term is beneficial to demodulate the partial discharge ultrasonic signal through the amplitude detection of the signal. Since the ultrasonic frequency band of the partial discharge signal is in the range of 20 kHz to 200 kHz, and The FFT spectra of are both narrow-band functions relative to the intermediate frequency ω IF Frequency band. Let its bandwidth be Δν, then Δν is much smaller than the intermediate frequency ω IF / 2π. Therefore, in the sin(ω (n) t) sine wave oscillation waveform in the Δs IF (t) signal, and The speed of change with time is slow, and when the limiting condition: Δt << 1 / Δv is satisfied, these two functions can be considered approximately constant within the Δt period. So, Δs (n) (t) The incremental signal is approximately a periodic function of time t (angular frequency ω IF ), but its amplitude and phase are both slowly modulated.

[0079] Using the Hilbert transform, first calculate the quadrature signal corresponding to the Δs (n) (t) incremental signal, as shown in the following formula:

[0080]

[0081] In the formula The difference from the Δs (n) (t) expression is that the oscillation function about the intermediate frequency ω IF Changes from a sine signal to a cosine signal, and the two are orthogonal signals to each other.

[0082] Then, taking Δs (n) (t) as the real part and as the imaginary part, a complex analytic signal form can be constructed:

[0083]

[0084] Then the modulus and phase angle of the complex analytic signal z (n) (t) can be given as:

[0085]

[0086]

[0087] Among them,

[0088]

[0089] It can be seen that |z (n) (t)|'s calculation result is independent of the intermediate frequency angular frequency ω IF , while χ(t) depends on a specific ω IF .

[0090] Finally, the amplitude modulation term and phase modulation term of the incremental signal Δs (n) (t) are respectively abbreviated as A (n) (t) and Φ (n) (t), and we can get:

[0091] A (n) (t) = 2|z (n) (t)|

[0092] Φ (n) (t) = χ(t) - (ω IF t + φ0)

[0093] For the convenience of data processing and analysis, the demodulation algorithm provided by the present invention first uses the Hilbert transform to obtain the amplitude corresponding to the detection signal, and then performs differential processing on it to obtain the modulation signal, and this measure has the same effect as the incremental transform.

[0094] The envelope extracted by using the Hilbert transform is named as the curve group r i (i = 1, 2,..., N), where N represents the number of segments divided in step 102. The calculation process of using the Hilbert transform to obtain the amplitude A p (t) corresponding to the detection signal s(t) is as Figure 3 shown.

[0095] Furthermore, after obtaining the first curve group in step 103 and before performing differential processing on the first curve group in step 104 to obtain the differential curve group, it may further include:

[0096] Step 1031: Perform white noise elimination processing on the first curve group to obtain the processed first curve group.

[0097] It should be noted that this step is to eliminate the power noise and phase noise of the laser in the Φ-OTDR system, and the processing method can be moving average processing to obtain the smoothed first curve group R i (i = 1, 2,..., M), where M is related to the value of the selected moving average step size k, that is, M = N / k. Then when performing step 104, the smoothed first curve group R i(i = 1, 2, ..., M) for differential processing, i.e., ΔR i = R i - R1.

[0098] Furthermore, step 105 mentioned in the first embodiment, the specific process of which includes:

[0099] Based on the time interval when the peak appears in the differential curve group, subtract the pulse signal trigger time from the time interval, then multiply by the speed of light and the equivalent group velocity in the optical fiber, and then determine the disturbance positioning interval according to half of the calculated product result.

[0100] It should be noted that according to the differential curve group obtained in step 105, determine the time interval [t1, t2] on the short-axis time axis where the peak of the differential curve group is located, subtract the actual trigger time Δt from this time interval, and then multiply by the speed of light and the equivalent group velocity v g in the optical fiber, and divide by 2 to obtain the actual disturbance positioning interval [z1, z2].

[0101] Furthermore, after obtaining the differential curve group in step 104, it may further include:

[0102] Step 1041: Based on the time point when the peak appears in the differential curve group, determine the amplitude at the time point of the first curve group as the reference amplitude. Based on the reference amplitude, recombine each waveform signal to obtain the vibration waveform signal of the external disturbance, and perform FFT transformation on the vibration waveform signal to obtain the main frequency of the vibration waveform signal, so as to judge whether the ultrasonic signal is generated by partial discharge according to the main frequency.

[0103] It should be noted that in this step, by selecting the amplitude on the original original waveform at the peak time point, a waveform array of N elements can be recombined, and the extracted new array is named p(t i ). The sampling interval of t i in this waveform array is exactly the repetition period of the detection optical pulse. The new waveform array is the vibration waveform of the external disturbance. Performing FFT transformation on the waveform can obtain its main frequency, and it can be judged whether the external disturbance is the ultrasonic signal generated by partial discharge according to this frequency. i

[0104] In addition, the execution order of step 1041 mentioned in this embodiment can be arranged after step 104, that is, this step can be executed synchronously with step 105, or before or after step 105.

[0105] To further illustrate the technical solution of the present application, this embodiment also provides a test example of measurement and demodulation in a Φ-OTDR fiber optic sensing system based on the method provided by the present application, as follows:

[0106] Using the method provided by this application, an ultrasonic signal with an analog frequency of f p = 20 kHz was measured and demodulated in a Φ-OTDR fiber optic sensing system. Among them, the trigger period of the detection pulse optical signal is 10 μs, the sampling rate of the acquisition system is 1 GS / s, the duration of the acquired waveform is taken as 2 ms, the fiber length is 758 m, and the time required for the optical signal to travel back and forth in the test fiber is 7.58 μs. The waveform segmentation in step 102 obtains the detection signal waveform of a certain segmented section as Figure 4 shown. The violently oscillating part of this waveform corresponds to the RBS scattered optical signal on the test fiber. The waveform length is 7.58 μs. This is the basic waveform of Φ-OTDR sensing detection, that is, it is considered that this detection waveform can remain stable when there is no external disturbance on the fiber. That is to say, this detection waveform can represent the unique "background fingerprint" of the measured fiber itself.

[0107] The differential curve group obtained by the method provided by this application is as Figure 5 shown. It can be seen from the figure that obvious peaks appear in the differential curve group within the short-axis time interval [5.19 μs, 5.22 μs]. As mentioned before, the total length of the test fiber in this embodiment is 758 m, and the sensing fiber segment wound on the piezoelectric actuator, that is, the disturbance source, is located in the interval [491 m, 495 m]. The trigger time of the trigger pulse in the experiment is 0.264 μs. After subtracting the trigger time from the differential curve fluctuation time interval, the positioning interval obtained is [492.6 m, 495.6 m], and the maximum deviation from the actual set position of the sensing fiber segment is 0.6 m.

[0108] Taking the short-axis time 5.210 μs as the peak time point for waveform reconstruction, selecting the amplitude of the ri original waveform at 5.210 μs, and reorganizing to obtain a waveform array with 200 elements. The duration of the acquired waveform in the invention embodiment is 2 ms, so the reorganized ultrasonic signal is also a waveform with a duration of 2 ms. Its time-domain waveform is as Figure 6 shown. It should be noted that the algorithm of the present invention is applicable to demodulating the waveform appearance of the disturbance signal in the time domain and does not really represent the original ultrasonic signal.

[0109] The FFT spectrum of the reconstructed waveform is as Figure 7 shown. It can be clearly seen from the spectrum diagram that the 20 kHz single-frequency ultrasonic signal set in the experiment, indicating that this method can effectively obtain the main frequency of the disturbance signal. In the actual engineering application of measuring partial discharge, it can be judged whether the disturbance signal is generated by partial discharge according to the main frequency of the FFT spectrum of the measured disturbance signal.

[0110] The above content is a detailed description of a partial discharge location method based on fiber optic sensing for measuring ultrasonic signals provided by the second embodiment of this application. The following is a detailed description of an embodiment of a partial discharge location device based on fiber optic sensing for measuring ultrasonic signals provided by this application.

[0111] Please refer to Figure 8 , the third embodiment of this application provides a partial discharge location device based on fiber optic sensing for measuring ultrasonic signals, including:

[0112] A signal acquisition unit 201, configured to acquire ultrasonic signals obtained through fiber optic sensing measurement;

[0113] A waveform segmentation unit 202, which performs waveform segmentation on the ultrasonic signals, and performs Hilbert transform on each segmented waveform signal to obtain the amplitude of the waveform signal;

[0114] A first curve group extraction unit 203, configured to extract the envelope line of the ultrasonic signal based on the amplitude of each waveform signal to obtain a first curve group;

[0115] A differential processing unit 204, configured to perform differential processing on the first curve group to obtain a differential curve group;

[0116] A location unit 205, configured to determine a disturbance location interval based on the time interval when the peak appears in the differential curve group, in combination with the speed of light and the equivalent group velocity in the optical fiber, and the pulse signal trigger time.

[0117] Further, the location unit 205 is specifically configured to:

[0118] Based on the time interval when the peak appears in the differential curve group, subtract the pulse signal trigger time from the time interval, then multiply by the speed of light and the equivalent group velocity in the optical fiber, and then determine the disturbance location interval according to half of the calculated product result.

[0119] Further, it further includes:

[0120] A waveform main frequency extraction unit 2041, configured to, based on the time point when the peak appears in the differential curve group, determine the amplitude of the first curve group at the time point as the reference amplitude, and based on the reference amplitude, recombine each waveform signal to obtain the vibration waveform signal of the external disturbance, and perform FFT transform on the vibration waveform signal to obtain the main frequency of the vibration waveform signal, so as to facilitate determining whether the ultrasonic signal is generated by partial discharge according to the main frequency.

[0121] Further, the waveform segmentation unit 202 is specifically configured to:

[0122] According to the pulse signal in the trigger waveform of the fiber optic sensing measurement system, the ultrasonic signal is segmented at equal intervals according to the trigger period of the pulse signal, and Hilbert transform is performed on each segmented waveform signal to obtain the amplitude of the waveform signal.

[0123] Furthermore, it further includes:

[0124] A white noise cancellation unit 2031, configured to perform white noise cancellation processing on the first curve group to obtain the processed first curve group.

[0125] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described terminals, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0126] In several embodiments provided by the present application, it should be understood that the disclosed terminals, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling, direct coupling, or communication connection can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in an electrical, mechanical, or other form.

[0127] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device including a series of steps or units does not necessarily need to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0128] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0129] In addition, in each embodiment of the present invention, each functional unit can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0130] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0131] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present application.

Claims

1. A method for localizing partial discharge by measuring ultrasonic signals based on fiber optic sensing, characterized in that, Including: Obtaining an ultrasonic signal measured by fiber optic sensing; According to the pulse signal in the trigger waveform of the fiber optic sensing measurement system, equally spacingly segmenting the ultrasonic signal at the trigger period of the pulse signal, and performing Hilbert transform on each segmented waveform signal to obtain the amplitude of each waveform signal; Based on the amplitudes of each waveform signal, extracting the envelope of the ultrasonic signal to obtain a first curve group; Performing differential processing on the first curve group to obtain a differential curve group; Based on the time interval where peaks appear in the differential curve group, combining the speed of light in the optical fiber, the equivalent group velocity, and the pulse signal trigger time, determining the disturbance positioning interval; Among them, the performing Hilbert transform on each segmented waveform signal to obtain the amplitude of each waveform signal specifically includes: Based on each segmented waveform signal, respectively calculating the corresponding incremental signal through an incremental transform formula, where the incremental transform formula is specifically: s (n) (t) = s 0 (t) - Δs (n) (t) where s 0 (t) represents the output signal of the Φ-OTDR system at an initial moment without ultrasonic disturbance or with ultrasonic disturbance, and Δs (n) (t) represents the increment signal of s L = t + nT p obtained at time t (n) (t) with respect to s 0 (t); ω IF is the difference frequency between the signal light and the reference light, φ0 is the phase delay of the Rayleigh backscattered light that is independent of ultrasonic disturbance at time t = t0, and φ n is the phase noise introduced by the laser; Using Hilbert transform to calculate the orthogonal signal corresponding to the incremental signal, and constructing a complex analytic signal with the incremental signal as the real part and the orthogonal signal as the imaginary part, so as to obtain the amplitude of each waveform signal according to the complex analytic signal.

2. The partial discharge location method based on fiber optic sensing for measuring ultrasonic signals according to claim 1, wherein, The determining the disturbance positioning interval based on the time interval where peaks appear in the differential curve group, combining the speed of light in the optical fiber, the equivalent group velocity, and the pulse signal trigger time specifically includes: Based on the time interval where peaks appear in the differential curve group, subtracting the pulse signal trigger time from the time interval, then multiplying by the speed of light in the optical fiber and the equivalent group velocity, and then determining the disturbance positioning interval according to half of the calculated product result.

3. A method for localizing partial discharge by measuring ultrasonic signals based on fiber optic sensing according to claim 1, characterized in that, Also including: Based on the time points where peaks appear in the differential curve group, determining the amplitude of the first curve group at the time points as the reference amplitude, based on the reference amplitude, recombining each waveform signal to obtain the vibration waveform signal of the external disturbance, and performing FFT transform on the vibration waveform signal to obtain the main frequency of the vibration waveform signal, so as to facilitate judging whether the ultrasonic signal is generated by partial discharge according to the main frequency.

4. A method for localizing partial discharge based on fiber optic sensing for measuring ultrasonic signals according to claim 1, characterized in that, Before the performing differential processing on the first curve group to obtain a differential curve group, it further includes: Performing white noise elimination processing on the first curve group to obtain a processed first curve group.

5. A partial discharge location device for measuring ultrasonic signals based on optical fiber sensing, characterized in that, Including: A signal acquisition unit for acquiring an ultrasonic signal measured by fiber optic sensing; A waveform segmentation unit for equally spacingly segmenting the ultrasonic signal at the trigger period of the pulse signal according to the pulse signal in the trigger waveform of the fiber optic sensing measurement system, and performing Hilbert transform on each segmented waveform signal to obtain the amplitude of each waveform signal; A first curve group extraction unit for extracting the envelope of the ultrasonic signal based on the amplitudes of each waveform signal to obtain a first curve group; A differential processing unit for performing differential processing on the first curve group to obtain a differential curve group; A positioning unit, configured to determine a disturbance positioning interval based on the time interval in which peaks appear in the differential curve group, in combination with the speed of light and the equivalent group velocity in the optical fiber and the triggering time of the pulse signal; Wherein, the step of performing Hilbert transform on each of the segmented waveform signals to obtain the amplitude of each of the waveform signals specifically includes: Based on each of the segmented waveform signals, respectively calculate the corresponding incremental signals through an incremental transformation formula, wherein the incremental transformation formula is specifically: s (n) s(t) = 0 s(t) - Δs (n) (t) φ IF = φ0 + φ n where s 0 (t) represents the output signal of the Φ-OTDR system at an initial moment without ultrasonic disturbance or with ultrasonic disturbance, and Δs (n) (t) represents the increment signal of s L = t + nT p at the subsequent moment t (n) (t) relative to s 0 (t); ω IF is the difference frequency between the signal light and the reference light, φ0 is the phase delay of the Rayleigh backscattered light that is independent of ultrasonic disturbance at the moment t = t0, and φ n is the phase noise introduced by the laser; Use Hilbert transform to calculate the orthogonal signal corresponding to the incremental signal, and construct a complex analytic signal with the incremental signal as the real part and the orthogonal signal as the imaginary part, so as to obtain the amplitude of each of the waveform signals according to the complex analytic signal.

6. The partial discharge positioning device for measuring ultrasonic signals based on optical fiber sensing according to claim 5, characterized in that, The positioning unit is specifically configured to: Based on the time interval in which peaks appear in the differential curve group, subtract the triggering time of the pulse signal from the time interval, then multiply by the speed of light and the equivalent group velocity in the optical fiber, and then determine the disturbance positioning interval according to half of the calculated product result.

7. The partial discharge positioning device for measuring ultrasonic signals based on optical fiber sensing according to claim 5, wherein Further included is: A waveform main frequency extraction unit, configured to, based on the time points at which peaks appear in the differential curve group, determine the amplitude of the first curve group at the time points as a reference amplitude, and based on the reference amplitude, recombine each of the waveform signals to obtain a vibration waveform signal of an external disturbance, and perform FFT transform on the vibration waveform signal to obtain the main frequency of the vibration waveform signal, so as to facilitate determining whether the ultrasonic signal is generated by partial discharge according to the main frequency.

8. The partial discharge positioning device for measuring ultrasonic signals based on fiber optic sensing according to claim 5, characterized in that, Further included is: A white noise cancellation unit, configured to perform white noise cancellation processing on the first curve group to obtain a processed first curve group.

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