GIS internal fastener loosening diagnosis method based on vibration sensor characteristics

Abstract

The invention discloses a GIS internal fastener loosening diagnosis method based on vibration sensor characteristics, and the method comprises the following steps: S01, data acquisition: obtaining vibration data of a monitoring air chamber in GIS equipment; s02, data acquisition: the data acquired in the S01 is transmitted to a computing terminal after passing through an acquirer; s03, data processing and analysis are carried out, vibration data processing and analysis are carried out on a computing terminal, different methods are used for processing and analyzing a low-frequency band and an ultrasonic band of the vibration data respectively, and the abnormal condition related to GIS internal fastener looseness is obtained. According to the method, low-frequency and high-frequency signals of the GIS are synchronously monitored, mechanical vibration and ultrasonic frequency bands are covered, and through a cross validation mode, the looseness condition of the fastener in the GIS can be more accurately and efficiently detected, the looseness type of the fastener in the GIS is determined, and relevant personnel can take corresponding measures conveniently to guarantee reliable and stable operation of GIS equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of internal anomaly diagnosis of GIS, and particularly to a method for diagnosing loosening of internal fasteners of GIS based on the characteristics of vibration sensors. Background Art

[0002] GIS (Gas Insulated Switchgear) is a gas-insulated metal-enclosed switchgear, which is an important high-voltage electrical equipment in the power system and is widely used in substations and power transmission and distribution networks. The reliability of its structural components is directly related to the safe operation of the equipment and the stability of the power grid. However, during long-term operation, key parts such as flange joints and areas with dense fasteners of GIS equipment are prone to loosen due to reasons such as vibration, thermal stress, or external impact. Such loosening will not only lead to a decline in equipment performance but may also cause serious failures, such as gas leakage, partial discharge, and even equipment failure, posing a threat to the safe operation of the power system.

[0003] Currently, the following technical solutions are mainly adopted for detecting loosening of GIS equipment structural components:

[0004] (1) Ultrasonic partial discharge detection technology. The use of ultrasonic methods for internal partial discharge detection of GIS has relatively mature industrial applications and has formed an industry standard (《DL / T 1250—2023 Guide for Application of Live Ultrasonic Partial Discharge Detection in Gas Insulated Metal Enclosed Switchgear》). Generally, it is considered that floating discharges inside GIS are caused by loosening of internal fasteners. During monitoring, a large number of points need to be arranged in the monitored gas chamber or the measuring points need to be frequently changed, resulting in high hardware or labor costs. It indirectly monitors the existence of loosening through floating discharges, but there is no necessary and sufficient relationship between loosening of internal fasteners and floating discharges.

[0005] (2) Acoustic emission sensor detection principle. The sensitive element inside the acoustic emission sensor is a piezoelectric ceramic. Using the resonance phenomenon, signals at the resonance frequency are amplified and collected. By selecting sensors with appropriate frequency bands, weak signals can be detected.

[0006] (3) Vibration detection technology for loosening of internal fasteners of GIS. According to laboratory results, when the internal fasteners of GIS are loose, obvious changes occur in its vibration signals in the range of 1 - 2 kHz, and a group standard 《TCES 021-2018 Technical Specification for Mechanical Vibration Detection of Gas Insulated Metal Enclosed Switchgear》 has been formed. However, there are currently no large-scale application examples. At the same time, the vibration signals are in the low-frequency range, and the signal performance is easily coupled with various phenomena, making it difficult to directly confirm whether the abnormal characteristics of the vibration signals are caused by loosening of internal fasteners.

[0007] The above several methods for detecting loosening of GIS equipment structural components cannot accurately judge the reasons for internal anomalies of GIS. Summary of the Invention

[0008] To overcome the above problems, the object of the present invention is to provide a diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors. This diagnostic method utilizes the linear response frequency spectrum and resonant frequency envelope demodulation spectrum of vibration sensors to synchronously monitor the low-frequency and high-frequency signals of GIS, covering the mechanical vibration and ultrasonic frequency bands. Through cross-verification, it can more accurately and efficiently detect the loosening of internal fasteners in GIS, clarify the types of loosening of internal fasteners in GIS, and facilitate relevant personnel to take corresponding measures to ensure the reliable and stable operation of GIS equipment.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors, comprising the following steps:

[0011] S01: Data acquisition, obtaining the vibration data of the monitored gas chamber in the GIS device;

[0012] S02: Data collection, transmitting the data obtained in S01 to the computing terminal after passing through the collector;

[0013] S03: Data processing and analysis, performing processing and analysis of the vibration data on the computing terminal, and using different methods to process and analyze the low-frequency band and ultrasonic band of the vibration data respectively to obtain abnormal conditions related to the loosening of internal fasteners in GIS. The specific process is as follows:

[0014] S031: Processing of low-frequency vibration signals;

[0015] S0311: Using a low-pass filter to screen the data in S02 to obtain low-frequency vibration signals,

[0016] S0312: Performing Fourier transform on the low-frequency vibration signals in S0311 to obtain the spectrum of the filtered vibration signals,

[0017] S0313: Calculating the relative amplitude eigenvalue of the 100 Hz harmonic , and determining whether there are abnormalities in the vibration signals;

[0018] S032: Processing of high-frequency vibration signals;

[0019] S0321: Using a high-pass filter to screen the data in S02 to obtain high-frequency vibration signals,

[0020] S0322: Using Hilbert transform to obtain the envelope spectrum for the high-frequency vibration signals in S0321,

[0021] S0323: The envelope spectrum in S0322 is subjected to Fourier transform to obtain the demodulation spectrum of the envelope signal, also known as the resonance demodulation spectrum.

[0022] S0324: Determine whether there is an abnormality in the resonance frequency signal according to the prominence of the spectral lines at 100 Hz and 200 Hz in the resonance demodulation spectrum.

[0023] S033: Cooperative diagnosis, comprehensively analyze the diagnosis results of the low-frequency vibration signal and the high-frequency vibration signal.

[0024] When both the low-frequency vibration signal and the high-frequency vibration signal results are abnormal, there is a phenomenon of loose fasteners inside the GIS at this time.

[0025] When either the low-frequency vibration signal result is abnormal and the high-frequency vibration signal result is normal or the high-frequency vibration signal result is abnormal and the low-frequency vibration signal result is normal, the abnormality does not originate from the loose fasteners inside the GIS at this time.

[0026] When both the low-frequency vibration signal and the high-frequency vibration signal results are normal, the GIS device is operating normally at this time.

[0027] As a further description of the present invention, the calculation process of the relative amplitude of the 100 Hz harmonic in S0313 is as follows:

[0028] The first step: Select As a characteristic quantity to normalize the vibration signal spectrum.

[0029] ,

[0030] Among them, Is the characteristic quantity corresponding to the nth harmonic of 100 Hz.

[0031] Is the amplitude of the 100 Hz frequency spectral line in the spectrum.

[0032] Is the amplitude of the nth harmonic of 100 Hz.

[0033] The second step: Compare the calculated characteristic quantity With the threshold in the standard to confirm the corresponding abnormal signal.

[0034] As a further description of the present invention, the specific method for judging the prominence of the spectral lines at 100 Hz and 200 Hz in S0324 is as follows:

[0035] The first step: Calculate the noise level of the envelope demodulation method spectrum, that is, its root mean square RMS:

[0036] ,

[0037] wherein is the i-th spectral line value of the envelope demodulation spectrum, and N is the total number of spectral lines in the demodulation spectrum;

[0038] Step 2: Calculate the signal significance of the 100 Hz spectral line and the 200 Hz spectral line respectively and :

[0039] ,

[0040] ,

[0041] wherein and are the amplitudes of the 100 Hz and 200 Hz spectral lines in the envelope demodulation spectrum respectively;

[0042] Step 3: Abnormality judgment. When and are both not less than 3, it is considered that the two spectral lines are significant and there is an abnormality in the ultrasonic frequency band.

[0043] As a further description of the present invention, the vibration data in S01 is obtained by acceleration sensors installed on the outer surfaces of each gas chamber of the GIS. Two sensors are arranged in one gas chamber, which are arranged in the horizontal and vertical directions on both sides of the middle of the gas chamber to be measured.

[0044] As a further description of the present invention, the sampling rate of the collector in S02 is not less than 2 times the resonance frequency of the GIS system, that is:

[0045] ,

[0046] wherein represents the sampling frequency of the sampler, represents the resonance frequency of the GIS system.

[0047] As a further description of the present invention, the filtering frequency band of the low-pass filter in S03 is the 10 - 2000 Hz frequency band, and the filtering frequency band of the high-pass filter is centered on the resonance frequency of the GIS system, with a frequency band of ±100 Hz for filtering to extract the resonance frequency signal.

[0048] As a further description of the present invention, the acceleration sensor has a lower limit of the frequency response range not higher than 30 Hz, an upper limit not lower than 2 kHz, a measurement range not less than ±5 g, and a resonance frequency not less than 20 kHz.

[0049] As a further description of the present invention, the acceleration sensor is installed using a detection fixture. The cross-section of the detection fixture is in an Ω-shaped structure, and the acceleration sensor is embedded therein. A limiting member made of an elastic material is also provided inside the detection fixture.

[0050] As a further description of the present invention, the diagnostic result is displayed on a display screen. The display content of the display screen includes:

[0051] The vibration signal waveform collected by the acceleration sensor;

[0052] The envelope spectrum and the harmonic component amplitude curve;

[0053] The determination conclusion of fastener loosening;

[0054] The specific position of the loosening point.

[0055] The beneficial effects of the present invention:

[0056] The diagnostic method for loosening of internal fasteners of GIS based on the characteristics of vibration sensors of the present invention includes the following steps: S01: Data acquisition, S02: Data collection, S03: Data processing and analysis. In the data acquisition stage of this diagnostic method, acceleration sensors are respectively arranged in the vertical and horizontal directions on both sides of the gas chamber to be measured, detecting the transmission of vibration in both the vertical and horizontal directions to ensure the accuracy of the acquired data. In the data collection stage, the collector is used to convert the original data, and the data collector is an A / D converter to facilitate the next-step data processing. In the data processing and analysis stage, the vibration data is subjected to Fourier transform in the low-frequency band to obtain the spectrum, thereby calculating the relative amplitude eigenvalue of the 100Hz harmonic to determine the abnormality. The Hilbert transform is used for the high-frequency band of the vibration data to obtain the envelope spectrum, and then the Fourier transform is used to obtain the demodulation spectrum of the envelope signal, as well as the significance of the spectral lines of 100Hz and 200Hz in the resonance demodulation spectrum to obtain the judgment of the abnormality. Finally, the results of the low-frequency band and the high-frequency band are comprehensively used for collaborative diagnosis. Overall, this diagnostic method utilizes the linear response frequency spectrum and the resonance frequency envelope demodulation spectrum of the vibration sensor to synchronously monitor the low-frequency and high-frequency signals of GIS, covering the mechanical vibration and ultrasonic frequency bands. Through the cross-validation method, it can more accurately and efficiently detect the loosening of internal fasteners of GIS, clarify the type of loosening of internal fasteners of GIS, and facilitate relevant personnel to take corresponding measures to ensure the reliable and stable operation of GIS equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a flow chart of the diagnostic method for loosening of internal fasteners of GIS based on the characteristics of vibration sensors proposed by the present invention;

[0058] Figure 2Flow chart of the specific process of data processing and analysis for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0059] Figure 3 Schematic diagram of the layout positions of acceleration sensors for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0060] Figure 4 GIS vibration spectrum of the internal structural members being fastened for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0061] Figure 5 GIS vibration spectrum of the internal structural members being loose for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0062] Figure 6 GIS resonance envelope demodulation spectrum of the internal structural members being fastened for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0063] Figure 7 GIS resonance envelope demodulation spectrum of the internal structural members being loose for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0064] Figure 8 Schematic diagram of the installation of acceleration sensors on the detection fixture for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0065] Figure 9 Typical vibration signal spectrum diagram of the GIS shell when the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention is operating normally;

[0066] Figure 10 Typical vibration signal spectrum diagram of the GIS shell when there is a defect of flange fastening loosening for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0067] Figure 11 Typical vibration signal spectrum diagram of the GIS shell when there is a defect of spring finger loosening for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0068] Figure 12 Typical vibration signal spectrum diagram of the GIS shell when there is a defect of poor contact of the contact for the diagnostic method of loosening of internal fasteners in GIS based on the characteristics of vibration sensors proposed by the present invention;

[0069] Figure 13 The time-frequency spectrum diagram of the typical vibration signal of the GIS shell when the grounding bolt is loose for the diagnosis method of the loosening of the internal fasteners of the GIS based on the characteristics of the vibration sensor proposed by the present invention;

[0070] Figure 14 The spectrum diagram of the typical vibration signal of the GIS shell when the shielding cover is displaced and loose for the diagnosis method of the loosening of the internal fasteners of the GIS based on the characteristics of the vibration sensor proposed by the present invention.

[0071] Description of the reference numerals

[0072] 1 - Detection fixture,

[0073] 2 - Acceleration sensor,

[0074] 3 - Limiting part. Detailed implementation manners

[0075] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention is made in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0076] In the following description, many specific details are set forth to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0077] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0078] The present invention is described in detail in conjunction with the schematic diagrams. When detailing the embodiments of the present invention, for the sake of convenience of explanation, the cross-sectional views showing the device structure will be enlarged locally not in accordance with the general scale, and the schematic diagrams are only examples and should not limit the protection scope of the present invention herein. In addition, in actual production, the three-dimensional spatial dimensions of length, width and depth should be included.

[0079] Meanwhile, in the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper, lower, inner, and outer" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first, second, or third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0080] Unless otherwise clearly defined and limited in the present invention, the terms "installation, connection, and coupling" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection, an electrical connection, or a direct connection, and can also be indirectly connected through an intermediate medium, or can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0081] As Figures 1 - 8 shown, it shows the specific implementation manners of the present invention:

[0082] Embodiment 1

[0083] A diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors includes the following steps:

[0084] S01: Data acquisition, obtaining the vibration data of the monitored gas chamber in the GIS device;

[0085] S02: Data collection, transmitting the data obtained in S01 to the calculation terminal after passing through the collector;

[0086] S03: Data processing and analysis, performing the processing and analysis of the vibration data on the calculation terminal, and respectively using different methods to process and analyze the low-frequency band and ultrasonic band of the vibration data to obtain the abnormal conditions related to the loosening of the internal fasteners in the GIS. The specific process is as follows:

[0087] S031: Processing of low-frequency vibration signals;

[0088] S0311: Using a low-pass filter to screen the data in S02 to obtain low-frequency vibration signals,

[0089] S0312: Performing Fourier transform on the low-frequency vibration signals in S0311 to obtain the spectrum of the filtered vibration signals,

[0090] S0313: Calculating the relative amplitude eigenvalue of the 100Hz harmonic , and determining whether there is an abnormality in the vibration signal;

[0091] S032: Processing of high-frequency vibration signals;

[0092] S0321: Use a high-pass filter to screen the data in S02 to obtain high-frequency vibration signals.

[0093] S0322: Use Hilbert transform to obtain the envelope spectrum of the high-frequency vibration signals in S0321.

[0094] S0323: Use Fourier transform on the envelope spectrum in S0322 to obtain the demodulation spectrum of the envelope signal, also known as the resonance demodulation spectrum.

[0095] S0324: Judge whether there is an abnormality in the resonance frequency signal according to the prominence of the spectral lines at 100 Hz and 200 Hz in the resonance demodulation spectrum.

[0096] S033: Cooperative diagnosis, comprehensively analyze the diagnosis results of low-frequency vibration signals and high-frequency vibration signals.

[0097] When both the low-frequency vibration signal and the high-frequency vibration signal results are abnormal, there is a phenomenon of loose fasteners inside the GIS at this time.

[0098] When either the low-frequency vibration signal result is abnormal and the high-frequency vibration signal result is normal or the high-frequency vibration signal result is abnormal and the low-frequency vibration signal result is normal, the abnormality does not originate from the loose fasteners inside the GIS at this time.

[0099] When both the low-frequency vibration signal and the high-frequency vibration signal results are normal, the GIS device is operating normally at this time.

[0100] In this embodiment, as Figure 1 , Figure 2 shown, in S01, in this diagnostic method, acceleration sensors 2 are respectively arranged in the vertical and horizontal directions on both sides of the gas chamber to be measured during the data acquisition stage, and the transmission of vibration in the vertical and horizontal directions is detected to ensure the accuracy of the acquired data.

[0101] In S02, during the data acquisition stage, the collector is used to convert the original data, and the data collector is an A / D converter, which is convenient for the next-step data processing.

[0102] In S03, during the data processing and analysis stage, Fourier transform is used on the low-frequency band of the vibration data to obtain the spectrum, thereby calculating the relative amplitude eigenvalue of the 100 Hz harmonic to determine the abnormality. Hilbert transform is used on the high-frequency band of the vibration data to obtain the envelope spectrum, and then Fourier transform is used to obtain the demodulation spectrum of the envelope signal, as well as the prominence of the spectral lines at 100 Hz and 200 Hz in the resonance demodulation spectrum to obtain the judgment of the abnormality. Finally, the results of the low-frequency band and the high-frequency band are comprehensively used for cooperative diagnosis.

[0103] Overall, this diagnostic method utilizes the linear response frequency spectrum of a vibration sensor and the resonant frequency envelope demodulation spectrum to synchronously monitor the low-frequency and high-frequency signals of GIS, covering both the mechanical vibration and ultrasonic frequency bands. Through cross-validation, it can more accurately and efficiently detect the looseness of internal fasteners in GIS, identify the types of loosened internal fasteners in GIS, and facilitate relevant personnel to take corresponding measures to ensure the reliable and stable operation of GIS equipment.

[0104] In this embodiment, the spectrum obtained after Fourier transform of the low-frequency vibration signal has differences under normal and abnormal conditions. As Figure 4 、 Figure 5 shown, it can be directly determined whether it is abnormal through the spectrogram.

[0105] In this embodiment, the resonant demodulation spectrum obtained after Hilbert transform and then Fourier transform of the high-frequency vibration signal has differences under normal and abnormal conditions. As Figure 6 、 Figure 7 shown, it can be directly determined whether it is abnormal through the resonant demodulation spectrum.

[0106] Specifically, the calculation process of the relative amplitude of the 100Hz harmonic in S0313 is as follows:

[0107] The first step: Select as the characteristic quantity to normalize the vibration signal spectrum,

[0108] ,

[0109] wherein, is the characteristic quantity corresponding to the nth harmonic of 100Hz,

[0110] is the amplitude of the 100Hz frequency line in the spectrum,

[0111] is the amplitude of the nth harmonic of 100Hz;

[0112] The second step: Compare the calculated characteristic quantity with the threshold value in the standard to confirm the corresponding abnormal signal.

[0113] In this embodiment, the relative amplitude of the 100Hz harmonic is calculated through the above steps and compared with the threshold value in the relevant standard to confirm the specific abnormal signal.

[0114] The determination of the specific abnormal signal is as follows:

[0115] Under normal operation:

[0116] The typical vibration signal spectrogram is as Figure 9As shown. Its time-domain signal shows obvious periodicity, the vibration amplitude is about 0.03V, and there is only an obvious vibration signal at the frequency point of 100Hz in the frequency-domain spectrum, and the corresponding amplitudes at other frequency points are almost zero.

[0117] When there is a defect in flange fastening looseness:

[0118] The typical vibration signal spectrum is as Figure 10 shown. Its time-domain signal shows a certain periodicity, the vibration amplitude is about 0.02V, and larger amplitudes appear at frequency points such as 50Hz, 200Hz, 1100Hz, 1500Hz, and 1800Hz in the frequency-domain spectrum. The ratio results of the amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency are shown in Table 1. The ratios of the amplitudes at the frequency points of 50Hz, 200Hz, 1100Hz, 1500Hz, and 1800Hz to the amplitude of the 100Hz fundamental frequency can be selected as the characteristic quantities of the flange fastening looseness defect.

[0119] Table 1 Ratio results of amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency when there is a defect in flange fastening looseness

[0120]

[0121] When there is a defect in spring finger looseness:

[0122] The typical vibration signal spectrum is as Figure 11 shown. Its time-domain signal shows a certain periodicity, the vibration amplitude is about 0.03V, and larger amplitudes appear at frequency points such as 50Hz, 200Hz, 1400Hz, 1500Hz, and 1800Hz in the frequency-domain spectrum. The ratio results of the amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency are shown in Table 2. The ratios of the amplitudes at the frequency points of 50Hz, 200Hz, 1400Hz, 1500Hz, and 1800Hz to the amplitude of the 100Hz fundamental frequency can be selected as the characteristic quantities of the spring finger looseness defect.

[0123] Table 2 Ratio results of amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency when there is a defect in spring finger looseness

[0124]

[0125] When there is a defect in poor contact of the contact:

[0126] The typical vibration signal spectrum is as Figure 12As shown. Its time-domain signal shows a certain periodicity, the vibration amplitude is about 0.025V, and relatively large amplitudes appear at frequency points such as 50Hz, 200Hz, and 1500Hz in the frequency-domain spectrum. The ratio results of the amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency are shown in Table 3. The ratios of the amplitudes at the 50Hz, 200Hz, and 1500Hz frequency points to the amplitude of the 100Hz fundamental frequency can be selected as the characteristic quantities for the defect of poor contact of the contact tip.

[0127] Table 3 Ratio results of amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency for the defect of poor contact of the contact tip

[0128]

[0129] For the defect of loose anchor bolts:

[0130] The typical vibration signal pattern is as Figure 13 shown. Its time-domain signal shows a certain periodicity, the vibration amplitude is about 0.03V, and relatively large amplitudes appear at each integer-hundred frequency point above 50Hz, 200Hz, and 1000Hz in the frequency-domain spectrum. The ratios of the 50Hz amplitude, 200Hz amplitude, and the average amplitude above 1000Hz to the amplitude of the 100Hz fundamental frequency are shown in Table 4. The ratios of the 50Hz amplitude, 200Hz amplitude, and the average amplitude above 1000Hz to the amplitude of the 100Hz fundamental frequency can be selected as the characteristic quantities for the defect of loose anchor bolts.

[0131] Table 4 Ratio results of amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency for the defect of loose anchor bolts

[0132]

[0133] For the defect of loose and displaced shielding cover:

[0134] The typical vibration signal pattern is as Figure 14 shown. Its time-domain signal shows a certain periodicity, the vibration amplitude is about 0.035V, and relatively large amplitudes appear at frequency points such as 50Hz, 200Hz, 1700Hz, and 1800Hz in the frequency-domain spectrum. The ratio results of the amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency are shown in Table 5. The ratios of the amplitudes at the 50Hz, 200Hz, and 1700Hz frequency points to the amplitude of the 100Hz fundamental frequency can be selected as the characteristic quantities for the defect of loose and displaced shielding cover.

[0135] Table 5 Ratio results of amplitudes at typical frequency points to the amplitude of the 100Hz fundamental frequency for the defect of loose and displaced shielding cover

[0136]

[0137] Specifically, the specific method for judging the significance of the spectral lines at 100Hz and 200Hz in S0324 is as follows:

[0138] Step 1: Calculate the noise level of the envelope demodulation spectrum, i.e., its root mean square (RMS):

[0139] ,

[0140] where is the value of the i-th spectral line of the envelope demodulation spectrum, and N is the total number of spectral lines in the demodulation spectrum;

[0141] Step 2: Calculate the signal significance of the 100 Hz spectral line and the 200 Hz spectral line respectively 、 :

[0142] ,

[0143] ,

[0144] where and are the amplitudes of the 100 Hz and 200 Hz spectral lines in the envelope demodulation spectrum respectively;

[0145] Step 3: Abnormality judgment. When and are both not less than 3, the two spectral lines are considered significant, and there is an abnormality in the ultrasonic frequency band.

[0146] Embodiment 2

[0147] Specifically, the vibration data in S01 is obtained by the acceleration sensors 2 installed on the outer surfaces of each gas chamber of the GIS. Two sensors are arranged in one gas chamber, respectively arranged in the horizontal and vertical directions on both sides of the middle of the gas chamber to be measured.

[0148] In this embodiment, as Figure 3 shown, it is a schematic diagram of the positions of the sensors of this diagnostic method in the gas chamber to be measured. Acceleration sensors 2 in the vertical and horizontal directions are arranged on both sides of the gas chamber to be measured. Since the propagation of vibration has directionality, the vibration conditions in the GIS device can be accurately collected through the sensors in the vertical and horizontal directions, which is convenient for subsequent data analysis.

[0149] Specifically, the sampling rate of the collector in S02 is not less than 2 times the resonance frequency of the GIS system, i.e.:

[0150] ,

[0151] where represents the sampling frequency of the sampler, represents the resonance frequency of the GIS system.

[0152] In this embodiment, setting the sampling frequency of the sampler can ensure the reliability of the influence of vibration data used for data analysis on the results.

[0153] Specifically, the filtering frequency band of the low-pass filter in S03 is the 10 - 2000 Hz frequency band, and the filtering frequency band of the high-pass filter is centered on the resonance frequency of the GIS system, with a frequency band of ±100 Hz for filtering to extract the resonance frequency signal.

[0154] Specifically, the acceleration sensor 2 has a lower limit of the frequency response range not higher than 30 Hz, an upper limit not lower than 2 kHz, a measurement range not lower than ±5 g, and a resonance frequency not lower than 20 kHz.

[0155] Embodiment Three

[0156] Specifically, the acceleration sensor 2 is installed using the detection fixture 1. The cross-section of the detection fixture 1 has an Ω-shaped structure, and the acceleration sensor 2 is embedded therein. The detection fixture 1 also has a limiting member 3 made of an elastic material inside.

[0157] In this embodiment, as Figure 8 shown, installing the acceleration sensor 2 using the above detection fixture 1 can fix its position and achieve reliable and effective acquisition of vibration data.

[0158] Specifically, the diagnostic result is displayed on a display screen. The display content of the display screen includes:

[0159] The vibration signal waveform collected by the acceleration sensor 2;

[0160] The envelope spectrum and the harmonic component amplitude curve;

[0161] The determination conclusion of fastener looseness;

[0162] The specific position of the loosening point.

[0163] In this embodiment, directly observing the diagnostic result and the analysis result of important nodes in the corresponding diagnostic process through the display screen facilitates timely identification of abnormal signals and accurate judgment of the looseness of the internal fasteners of the GIS device.

[0164] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present invention.

[0165] Many other changes and modifications can be made without departing from the concept and scope of the present invention. It should be understood that the present invention is not limited to specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors, characterized in that It includes the following steps: S01: Data acquisition, acquiring the vibration data of the monitoring gas chamber in the GIS device; S02: Data collection, transmitting the data acquired in S01 to the computing terminal after passing through the collector; S03: Data processing and analysis, processing and analyzing the vibration data at the computing terminal, using different methods to process and analyze the low-frequency band and ultrasonic band of the vibration data respectively, and obtaining the abnormal conditions related to the loosening of the internal fasteners of the GIS. The specific process is as follows: S031: Processing of low-frequency vibration signals; S0311: Using a low-pass filter to screen the data in S02 to obtain low-frequency vibration signals, S0312: Performing Fourier transform on the low-frequency vibration signals in S0311 to obtain the spectrum of the filtered vibration signals, S0313: Calculate the relative amplitude eigenvalue of the 100Hz harmonic wave to determine whether there is an abnormality in the vibration signal , and determine whether there is an abnormality in the vibration signal S0314: Obtaining the vibration diagnosis conclusion; S032: Processing of high-frequency vibration signals; S0321: Using a high-pass filter to screen the data in S02 to obtain high-frequency vibration signals, S0322: Using Hilbert transform to obtain the envelope spectrum for the high-frequency vibration signals in S0321, S0323: Using Fourier transform on the envelope spectrum in S0322 to obtain the demodulation spectrum of the envelope signal, also known as the resonance demodulation spectrum, S0324: Judging whether the resonance frequency signal is abnormal according to the significance of the spectral lines at 100 Hz and 200 Hz in the resonance demodulation spectrum, S0325: Obtaining the harmonic diagnosis conclusion; S033: Cooperative diagnosis, comprehensively analyzing the diagnosis results of the low-frequency vibration signals and high-frequency vibration signals, When both the low-frequency vibration signal and the high-frequency vibration signal results are abnormal, there is a phenomenon of loosening of the internal fasteners in the GIS at this time, When either the low-frequency vibration signal result is abnormal and the high-frequency vibration signal result is normal, or the high-frequency vibration signal result is abnormal and the low-frequency vibration signal result is normal, the abnormality does not originate from the loosening of the internal fasteners of the GIS at this time, When both the low-frequency vibration signal and the high-frequency vibration signal results are normal, the GIS device is operating normally at this time.

2. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 1, characterized in that, The calculation process of the relative amplitude of the 100 Hz harmonic in S0313 is as follows: Step 1: Select as a characteristic quantity to normalize the vibration signal spectrum. ， Among them, is the characteristic quantity corresponding to the nth harmonic of 100Hz. is the amplitude of the spectral line at 100 Hz in the spectrum, is the amplitude of the nth harmonic at 100 Hz; Step 2: Compare the calculated characteristic quantities with the threshold values in the standard to confirm the corresponding abnormal signals.

3. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 1, characterized in that, The specific judgment method for the significance of the spectral lines at 100 Hz and 200 Hz in S0324 is as follows: The first step: calculating the noise level of the envelope demodulation method spectrum, that is, its root mean square RMS: ， wherein is the i-th spectral line value of the envelope demodulation spectrum, and N is the total number of spectral lines in the demodulation spectrum; Step 2: Calculate the signal significance of the 100 Hz spectral line and the 200 Hz spectral line respectively , : ， ， where and are the amplitudes of the spectral lines at 100 Hz and 200 Hz in the envelope demodulation spectrum, respectively; Step 3: Abnormality judgment. When and are both not less than 3, the two spectral lines are considered significant and there is an abnormality in the ultrasonic frequency band.

4. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 1, characterized in that, The vibration data in S01 is acquired through the acceleration sensors (2) installed on the outer surfaces of each gas chamber of the GIS. Two sensors are arranged in one gas chamber, respectively arranged in the horizontal and vertical directions on both sides of the middle of the gas chamber to be measured.

5. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 1, characterized in that, The sampling rate of the collector in S02 is not less than 2 times the resonance frequency of the GIS system, that is: ， Among them, represents the sampling frequency of the sampler, represents the resonance frequency of the GIS system.

6. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 1, characterized in that, In S03, the filtering frequency band of the low-pass filter is the 10 - 2000 Hz frequency band, and the filtering frequency band of the high-pass filter is centered on the resonance frequency of the GIS system, with a frequency band of ±100 Hz for filtering to extract the resonance frequency signal.

7. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 4, characterized in that, The acceleration sensor (2) has a lower limit of the frequency response range not higher than 30 Hz, an upper limit not lower than 2 kHz, a measurement range not less than ±5 g, and a resonance frequency not less than 20 kHz.

8. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 4, characterized in that, The acceleration sensor (2) is installed using a detection fixture (1). The cross-section of the detection fixture (1) has an Ω-shaped structure, and the acceleration sensor (2) is embedded therein. A limiting member (3) made of an elastic material is also provided inside the detection fixture (1).

9. The diagnostic method for loosening of internal fasteners in GIS based on the characteristics of vibration sensors according to claim 1, characterized in that, The diagnostic results are displayed on a display screen. The display content of the display screen includes: The vibration signal waveform collected by the acceleration sensor (2); The envelope spectrum and the harmonic component amplitude curve; The determination conclusion of fastener looseness; The specific position of the loosening point.

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