Detection method for discharge ultrasonic signal

Abstract

The invention provides a detection method for a discharge ultrasonic signal, and the method comprises the steps: collecting a radiation photon signal and a sound wave signal of a discharge pulse train of partial discharge; determining a time sequence corresponding to the radiation photon signal, and determining a corresponding time sequence matrix according to the event sequence; determining sound wave signal intensity corresponding to the time sequence matrix according to the sound wave signal, and outputting a sound wave intensity sequence; determining a mean square value corresponding to each sound wave intensity sequence, and determining a time point in the time sequence matrix corresponding to the maximum mean square value; and taking the sound wave intensity corresponding to the time points in all the determined time sequence matrixes as a final output ultrasonic signal intensity sequence to obtain a high-time-resolution ultrasonic intensity sequence. According to the method, the radiation photon signal and the sound wave signal generated by partial discharge are synchronously collected, the high-time-resolution ultrasonic intensity sequence is obtained, a basis is provided for positioning and evaluation of a partial discharge event, and the time resolution of ultrasonic pulse detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system automation, and particularly to a method for detecting discharge ultrasonic signals. Background Art

[0002] In the detection of power equipment, the detection of partial discharge is of great significance for preventing equipment failures. The ultrasonic detection method is a commonly used means for detecting partial discharge, which has the advantages of non-contact, high sensitivity, strong anti-interference ability, etc. However, in the statistical diagnosis of partial discharge, due to the relatively long oscillation duration of ultrasonic signals, signal overlap occurs when multiple discharge pulses are generated successively. Therefore, the pulse resolution of traditional ultrasonic detection is not high, and it is difficult to be directly used for phase statistical pattern diagnosis and acoustic positioning based on multiple ultrasonic signals, etc. Summary of the Invention

[0003] The object of the present invention is to propose a method for detecting discharge ultrasonic signals, and solve the technical problem of how to obtain the time series of the intensity of discharge ultrasonic signals according to weak light signals to improve the time resolution of ultrasonic pulse detection.

[0004] On the one hand, a method for detecting discharge ultrasonic signals is provided, including:

[0005] Collecting the radiation photon signals and acoustic signals of the discharge pulse group of partial discharge;

[0006] Determining the time series corresponding to the radiation photon signals, and determining the corresponding time series matrix according to the event sequence; determining the acoustic signal intensity corresponding to the time series matrix according to the acoustic signals, and outputting it as the acoustic intensity sequence;

[0007] Determining the mean square value corresponding to each acoustic intensity sequence, and determining the time point in the time series matrix corresponding to the maximum mean square value;

[0008] Taking the acoustic intensities corresponding to the time points in all the determined time series matrices as the finally output ultrasonic signal intensity sequence, and obtaining the ultrasonic intensity sequence with high time resolution.

[0009] Preferably, the radiation photon signal is the weak light detection signal of partial discharge collected by a preset weak light detection device, wherein the sampling rate of the acquisition channel of the weak light detection device is greater than or equal to a preset sampling value and the acquisition depth is greater than or equal to a preset depth value.

[0010] Preferably, the quantum efficiency of the weak light detection device is not lower than a preset efficiency value, the wavelength range covers a preset wavelength range value, the response time is less than a preset time value, and the field of view angle is not lower than a first angle value.

[0011] Preferably, the acoustic wave signal is an acoustic wave of partial discharge collected by a preset ultrasonic sensor, wherein the bandwidth of the ultrasonic sensor covers a preset bandwidth range value and the sensitivity is not lower than a preset sensitivity value, and the detection angle of the ultrasonic sensor is not lower than a first angle value.

[0012] Preferably, the determining the corresponding time series matrix according to the event sequence includes adding the corresponding time difference to each time point in the time series corresponding to the radiation photon signal to obtain the corresponding time series matrix.

[0013] Preferably, the time difference is determined by the following formula

[0014] Δt = 0.05n

[0015] where Δt is the time difference and n is a positive integer.

[0016] Preferably, the determining the acoustic wave signal intensity corresponding to the time series matrix according to the acoustic wave signal includes obtaining the corresponding voltage frequency and determining the maximum value of the time difference according to the voltage frequency;

[0017] Retrieving the time series segment in the time series matrix according to the maximum value of the time difference, and forming an acoustic wave intensity sequence with the acoustic wave signal intensities corresponding to the event sequence segment.

[0018] Preferably, the determining the maximum value of the time difference according to the voltage frequency includes determining the maximum value of n according to the following formula and determining the maximum value of the corresponding time difference according to the maximum value of n,

[0019]

[0020] where k is the maximum value of n and f is the voltage frequency.

[0021] Preferably, the mean square value corresponding to each acoustic wave intensity sequence is determined according to the following formula

[0022]

[0023] where m is the length of the acoustic wave intensity sequence, {q i} is the acoustic wave intensity sequence, ij is the coordinate of each acoustic wave intensity in the acoustic wave intensity sequence, x i is the mean square value, and i is the serial number of the mean square value.

[0024] Preferably, it further includes that when there are multiple ultrasonic sensors at different positions for partial discharge positioning, determining the mean square value corresponding to each acoustic wave intensity sequence through the time series pair corresponding to the radiation photon signal, and determining the time point in the time series matrix corresponding to the maximum mean square value;

[0025] Take the acoustic wave intensities corresponding to the time points in all the determined time series matrices as the ultrasonic signal intensity sequences of the final output, and obtain the ultrasonic signal intensity sequences at different positions.

[0026] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0027] The detection method for discharge ultrasonic signals provided by the present invention uses a weak light detection device and a piezoelectric ultrasonic sensor to synchronously collect the radiation photon signals and acoustic wave signals generated by partial discharge, and converts the time series into a variable-step time series; for each converted time series, determine the corresponding acoustic wave signal intensity and record it as an acoustic wave intensity sequence; calculate the mean square value of each acoustic wave intensity sequence, and find the time series corresponding to the maximum mean square value to determine the maximum value of the ultrasonic signal intensity; take the acoustic wave intensity of the time series corresponding to the determined maximum mean square value as the ultrasonic signal intensity sequence of the final output, and obtain a high-time-resolution ultrasonic intensity sequence, which provides a basis for the positioning and evaluation of partial discharge events and improves the time resolution of ultrasonic pulse detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

[0029] Figure 1 It is a schematic diagram of the main process of a detection method for discharge ultrasonic signals in an embodiment of the present invention.

[0030] Figure 2 It is a phase statistical map in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings.

[0032] As Figure 1 shown, it is a schematic diagram of an embodiment of a detection method for discharge ultrasonic signals provided by the present invention. In this embodiment, the method includes the following steps:

[0033] Step S1, collect the radiation photon signals and acoustic signals of the discharge pulse group of partial discharge; understandably, use a weak light detection device, an ultrasonic sensor, and a multi-channel synchronous acquisition channel to synchronously collect the radiation photon signals and acoustic signals of the discharge pulse group when partial discharge occurs. The two acquisition channels of the weak light detection device and the ultrasonic sensor need to be synchronously triggered, and the trigger time difference ≤ 10 ns.

[0034] In one embodiment, the radiation photon signal is the weak light detection signal of partial discharge collected by a preset weak light detection device, where the sampling rate of the acquisition channel of the weak light detection device is greater than or equal to a preset sampling value and the acquisition depth is greater than or equal to a preset depth value. The photon efficiency of the weak light detection device is not less than a preset efficiency value, the wavelength range covers a preset wavelength range value, the response time is less than a preset time value, and the field of view angle is not less than a first angle value. In this embodiment, the sampling rate of the acquisition channel of the weak light detection device ≥ 5 Gs / s, and the acquisition depth ≥ 200 Mb; the photon efficiency of the weak light detection device is not less than 30%, the wavelength range covers 350 nm - 750 nm, the response time is less than 10 ps, and the field of view angle is not less than 70°.

[0035] In one embodiment, the acoustic signal is the acoustic wave of partial discharge collected by a preset ultrasonic sensor, where the bandwidth of the ultrasonic sensor covers a preset bandwidth range value and the sensitivity is not less than a preset sensitivity value, and the detection angle of the ultrasonic sensor is not less than a first angle value. In this embodiment, the bandwidth of the ultrasonic sensor covers 20 kHz - 120 kHz, and the sensitivity is not less than 300 mV / g; the detection angle of the ultrasonic sensor is not less than 70°.

[0036] Step S2, determine the time series corresponding to the radiation photon signal, and determine the corresponding time series matrix according to this event sequence; determine the acoustic signal intensity corresponding to the time series matrix according to the acoustic signal, and output it as the acoustic intensity sequence; understandably, convert each time point t i in the time series output by the weak light detection device into t i +Δt to generate a time series matrix; calculate the acoustic signal intensity q i corresponding to the time series t i +Δt, and record it as the acoustic intensity sequence {q i}.

[0037] In one embodiment, the determining the corresponding time series matrix according to this event sequence includes adding the corresponding time difference to each time point in the time series corresponding to the radiation photon signal to obtain the corresponding time series matrix. The time difference is determined by the following formula

[0038] Δt = 0.05n

[0039] Wherein, Δt is the time difference (unit: ms), and n is a positive integer.

[0040] In one embodiment, determining the acoustic signal intensity corresponding to the time series matrix according to the acoustic wave signal includes obtaining the corresponding voltage frequency and determining the maximum value of the time difference according to the voltage frequency; retrieving the time series segment in the time series matrix according to the maximum value of the time difference, and forming the acoustic wave intensity sequence with the acoustic wave signal intensities corresponding to the event sequence segment.

[0041] Determining the maximum value of the time difference according to the voltage frequency includes determining the maximum value of n according to the following formula, and determining the maximum value of the corresponding time difference according to the maximum value of n,

[0042]

[0043] Wherein, k is the maximum value of n, and f is the voltage frequency.

[0044] Step S3, determining the mean square value corresponding to each acoustic wave intensity sequence, and determining the time point in the time series matrix corresponding to the maximum mean square value; for each intensity sequence {q i}, calculating the mean square value x i , and obtaining the n value corresponding to the maximum mean square value x max , and recording t i +Δt at this time.

[0045] In one embodiment, determining the mean square value corresponding to each acoustic wave intensity sequence according to the following formula,

[0046]

[0047] Wherein, m is the length of the acoustic wave intensity sequence, {q i} is the acoustic wave intensity sequence, ij is the coordinate of each acoustic wave intensity in the acoustic wave intensity sequence, x i is the mean square value, and i is the serial number of the mean square value.

[0048] Step S4, taking the acoustic wave intensities corresponding to the time points in all the determined time series matrices as the finally output ultrasonic signal intensity sequence, and obtaining the ultrasonic intensity sequence with high time resolution. Taking the acoustic wave intensity corresponding to this time series t i +Δt as the finally output ultrasonic signal intensity sequence {t i +Δt, q i}, and this sequence is the ultrasonic intensity sequence with high time resolution.

[0049] An embodiment further includes that when there are multiple ultrasonic sensors at different positions for partial discharge location, the mean square value corresponding to each acoustic wave intensity sequence is determined through the time series pair corresponding to the radiation photon signal, and the time point in the time series matrix corresponding to the maximum mean square value is determined; all the time points in the determined time series matrices are used as the acoustic wave intensities corresponding to the final output ultrasonic signal intensity sequences, and the ultrasonic signal intensity sequences at different positions are obtained. It can be understood that when there are multiple ultrasonic sensors at different positions for partial discharge location, the time series obtained by weak light detection can be used to process the acquisition output signals of each ultrasonic sensor, and the above steps are executed to obtain the ultrasonic intensity sequences at different positions.

[0050] Specific embodiment, sensor selection and acquisition channel parameters: Weak light detection device: Select a photomultiplier tube (PMT) with a quantum efficiency of 35%, whose wavelength range covers 350nm to 750nm, the response time is 5ps, and the field of view angle is 75°. The sampling rate of the acquisition channel of this PMT is 5Gs / s, and the acquisition depth is 250Mb; Piezoelectric ultrasonic sensor: Select three piezoelectric ultrasonic sensors with a bandwidth covering 20kHz to 120kHz, and the sensitivity of each is 350mV / g, and the detection angle is 75°. These sensors are connected to the weak light detection device through a synchronous acquisition channel to ensure that the trigger time difference does not exceed 10ns.

[0051] Synchronous acquisition of signals: When partial discharge occurs, the weak light detection device and the three piezoelectric ultrasonic sensors simultaneously acquire the radiation photon signal and the acoustic wave signal of the discharge pulse group through the synchronous acquisition channel.

[0052] Time series conversion: Assume that the time series output by the weak light detection device is a relatively random series t i ={12.1, 23.3, 35.2, 47.2, 58.6} (unit: ms). Convert these time points to t i +Δt, where Δt = 0.05n, n = 1 to 50.

[0053] Calculation of acoustic wave signal intensity: For each n value, we calculate the acoustic wave signal intensity q i corresponding to the ultrasonic sensor. Assume that for n = 1, the acoustic wave signal intensity sequence {q i} is {22.2, 28.2, 17.3, 25.9, 30.7} (unit: dB).

[0054] Calculation of mean square value and determination of maximum value: Calculate the mean square value x i of each intensity sequence, and find the maximum mean square value x max corresponding to n = 26, x max = 29.8 (unit: dB).

[0055] Ultrasonic signal intensity output: The finally output ultrasonic signal intensity sequence

[0056] The acoustic wave intensity sequence {t i +Δt, q i} when n = 26:

[0057] t i +Δt == {13.4, 24.6, 36.5, 48.5, 59.9}

[0058] q i = {22.2, 28.2, 17.3, 25.9, 30.7}

[0059] After correlating the above ultrasonic signal intensity sequence with the voltage phase, {t i +Δt, q i} can be converted into {φ, q i}, and finally a clear phase statistical pattern (PRPD) can be plotted, as Figure 2 shown.

[0060] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0061] The detection method for discharge ultrasonic signals provided by the present invention uses a weak light detection device and a piezoelectric ultrasonic sensor to synchronously collect the radiation photon signals and acoustic wave signals generated by partial discharge, and converts the time series into a variable-step time series; for each converted time series, the corresponding acoustic wave signal intensity is determined and recorded as the acoustic wave intensity sequence; the mean square value of each acoustic wave intensity sequence is calculated, and the time series corresponding to the maximum mean square value is found to determine the maximum value of the ultrasonic signal intensity; the acoustic wave intensity of the time series corresponding to the determined maximum mean square value is used as the finally output ultrasonic signal intensity sequence, obtaining a high-time-resolution ultrasonic intensity sequence, providing a basis for the positioning and evaluation of partial discharge events, and improving the time resolution of ultrasonic pulse detection.

[0062] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited by this. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for detecting a discharge ultrasonic signal, characterized in that: include: Collect radiation photon signals and acoustic wave signals of the discharge pulse group of partial discharge; Determine the time series corresponding to the radiation photon signal, and determine the corresponding time series matrix according to the event sequence; determine the sound wave signal intensity corresponding to the time series matrix according to the sound wave signal, and output it as a sound wave intensity sequence; Determine the mean square value corresponding to each sound wave intensity sequence, and determine the time point in the time series matrix corresponding to the maximum mean square value; The sound wave intensities corresponding to the time points in all the determined time series matrices are used as the final output ultrasonic signal intensity sequence to obtain a high time resolution ultrasonic intensity sequence.

2. The method according to claim 1, characterized in that The radiation photon signal is a weak light detection signal of local discharge collected by a preset weak light detection device, wherein the sampling rate of the collection channel of the weak light detection device is greater than or equal to a preset sampling value and the collection depth is greater than or equal to a preset depth value.

3. The method according to claim 2, characterized in that The light quantum efficiency of the weak light detection device is not lower than a preset efficiency value, the wavelength range covers a preset wavelength range value, the response time is less than a preset time value, and the field of view angle is not lower than a first angle value.

4. The method according to claim 3, characterized in that The sound wave signal is a sound wave of local discharge collected by a preset ultrasonic sensor, wherein the bandwidth coverage of the ultrasonic sensor is within a preset bandwidth range value and the sensitivity is not lower than a preset sensitivity value, and the detection angle of the ultrasonic sensor is not lower than a first angle value.

5. The method according to claim 1, characterized in that Determining the corresponding time series matrix according to the event sequence includes adding the corresponding time difference to each time point in the time series corresponding to the radiation photon signal to obtain the corresponding time series matrix.

6. The method according to claim 5, characterized in that The time difference is determined by the following formula, Δt=0.05n in, Δ t is the time difference, and n is a positive integer.

7. The method according to claim 6, characterized in that Determining the intensity of the acoustic wave signal corresponding to the time series matrix according to the acoustic wave signal includes obtaining the corresponding voltage frequency and determining the maximum value of the time difference according to the voltage frequency; The time series segment in the time series matrix is ​​retrieved according to the maximum value of the time difference, and the sound wave signal intensities corresponding to the event sequence segment are combined into a sound wave intensity sequence.

8. The method according to claim 7, characterized in that Determining the maximum value of the time difference according to the voltage frequency includes determining the maximum value of n according to the following formula, and determining the corresponding maximum value of the time difference according to the maximum value of n, Among them, k is the maximum value of n, and f is the voltage frequency.

9. The method according to claim 1, characterized in that Determine the mean square value corresponding to each sound wave intensity sequence according to the following formula: Where m is the length of the sound wave intensity sequence, {q i } is the sound wave intensity sequence, ij is the coordinate of each sound wave intensity in the sound wave intensity sequence, x i is the mean square value, and i is the sequence number of the mean square value.

10. The method according to claim 4, characterized in that It also includes, when there are multiple ultrasonic sensors at different positions for local discharge positioning, determining the mean square value corresponding to each sound wave intensity sequence through the time series pair corresponding to the radiation photon signal, and determining the time point in the time series matrix corresponding to the maximum mean square value; The sound wave intensities corresponding to the time points in all the determined time series matrices are used as the ultrasonic signal intensity sequences finally outputted to obtain ultrasonic signal intensity sequences at different positions.

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