Positioning system and positioning method for partial discharge in gas insulated electrical equipment

Abstract

The invention provides a positioning system and a positioning method for partial discharge in gas insulated electrical equipment, and belongs to the technical field of insulator tests. The invention discloses a method for positioning internal partial discharge of gas insulated electrical equipment. The method comprises the following steps: S11, acquiring pulse packets acquired by two acoustic sensors; s12, acquiring the group velocity of the pulse packets based on the distance between the two acoustic sensors and the time difference of the two corresponding pulse packets; s13, acquiring the propagation time of a pulse packet corresponding to one target acoustic sensor; and S14, based on the group velocity and the propagation time of the pulse packet, determining a partial discharge position according to the position of the target acoustic sensor. According to the method, the acoustic sensors are arranged at multiple points on the gas insulated electrical equipment, so that the comprehensiveness of early fault signal positioning can be expanded; through signal analysis of a plurality of groups of acoustic sensors with known distance differences, the position of a partial discharge sound source can be rapidly obtained, and rapid and accurate positioning of a partial discharge fault point is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of insulator testing, and in particular relates to a positioning system and a positioning method for accidental partial discharge inside gas-insulated electrical equipment. Background Art

[0002] Gas-insulated electrical equipment (GIS or GIL) has the advantages of being unaffected by the natural environment, high reliability, large energy transmission, low loss, and strong anti-electromagnetic interference ability. It has been used in many ultra-high voltage transmission projects in China.

[0003] However, the failure rate of gas-insulated electrical equipment is relatively high. At the same time, it is affected by the electromagnetic shielding of the metal shell and the waveform conversion at the interface of heterogeneous shells. The reliability of traditional high-frequency electromagnetic wave partial discharge monitoring and ultrasonic partial discharge monitoring is insufficient, especially for the detection efficiency of early incidental partial discharge signals is greatly reduced.

[0004] Therefore, studying effective methods for detecting and locating early incidental partial discharge signals in gas-insulated electrical equipment has positive significance for equipment safety status identification and early intervention. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an array demodulation reverse positioning system and positioning method for occasional partial discharge signals inside gas-insulated electrical equipment in response to the deficiencies of the existing technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for locating partial discharge inside gas-insulated electrical equipment is implemented using a positioning system. The positioning system includes multiple acoustic sensors arranged on the surface of the gas-insulated electrical equipment, and the arrangement direction of the acoustic sensors is parallel to the axis of the gas-insulated electrical equipment. The positioning method includes: S11, obtaining pulse packets collected by two acoustic sensors; S12, obtaining the group velocity of the pulse packets based on the distance between the two acoustic sensors and the time difference between the two corresponding pulse packets; S13, obtaining the propagation time of the pulse packet corresponding to one of the target acoustic sensors; S14, determining the partial discharge position according to the position of the target acoustic sensor based on the group velocity and propagation time of the pulse packet.

[0007] Furthermore, the positioning method further includes: S15, repeatedly selecting two different acoustic sensors and repeatedly executing steps S11-S14 to localize the sound source until different pairwise combinations of all acoustic sensors are selected; S16, determining the accurate partial discharge position based on the results of multiple sound source localizations.

[0008] Furthermore, the positioning method further includes, before step S11: S10, determining whether the partial discharge position is located in the arrangement area of ​​the acoustic sensor; if not, continuing to execute subsequent steps; if so, directly locating the partial discharge position based on the sound velocity of sulfur hexafluoride gas in the gas-insulated electrical equipment and the position of the acoustic sensor.

[0009] Furthermore, the method for determining whether the partial discharge position is located in the arrangement area of ​​the acoustic sensors includes: when the waveforms collected by all acoustic sensors are the same and the amplitudes are close, determining that the partial discharge position is located in the arrangement area of ​​the acoustic sensors.

[0010] Furthermore, the method for obtaining the propagation time of the pulse packet corresponding to one of the target acoustic sensors includes: S131, performing Fourier transform on the two pulse packets to obtain time domain waveforms of different frequencies in the two pulse packets; S132, selecting two typical frequency waves from each of the two pulse packets, and the waveforms of the typical frequency waves corresponding to different pulse packets are consistent; S133, based on the time domain difference between the two typical frequency waves in each pulse packet, obtaining the speed difference of the typical frequency waves; S134, based on the first wave position difference and the speed difference of the typical frequency waves, obtaining the propagation time of the pulse packet corresponding to the target acoustic sensor.

[0011] Furthermore, the method for obtaining time domain waveforms of different frequencies in two pulse packets includes: The initial signal of the partial discharge signal wave is characterized by: ; In the frequency domain, it is expressed as ; spread for a period of time or a distance After that, it is expressed as ; Considering the dispersion effect, the pulse packet collected by the acoustic sensor is expressed as: .

[0012] Through Fourier transform, the time domain representation of different frequencies is obtained as follows: ; Where u is the time parameter of the pulse, f is the frequency, and s is the bandwidth.

[0013] A localization system for partial discharge inside gas-insulated electrical equipment comprises a plurality of acoustic signal amplifying diaphragms adhered to the surface of the gas-insulated electrical equipment, acoustic sensors coupled one-to-one with the acoustic signal amplifying diaphragms, and a detection host connected to the acoustic sensors; the arrangement directions of the acoustic signal amplifying diaphragms and the acoustic sensors are both parallel to the axis of the gas-insulated electrical equipment; the detection host is used to locate the position of the partial discharge based on the pulse packets detected by the acoustic sensors; the acoustic signal amplifying diaphragms are used to amplify pulse signals, are all rectangular in shape, and the length direction of the acoustic signal amplifying diaphragms is parallel to the axis of the gas-insulated electrical equipment; the acoustic signal amplifying diaphragms are made of carbon nanotubes.

[0014] Furthermore, it also includes a laser, a first fiber coupler, an acousto-optic modulator, a fiber amplifier, an optical circulator and a single-mode optical fiber connected in sequence according to the laser transmission direction; it also includes a second fiber coupler and a photodetector of the laser connected in sequence according to the laser transmission direction; the optical circulator and the first fiber coupler are optically connected to the second fiber coupler, and the photodetector is electrically connected to the detection host; and the acoustic sensors are optically connected to the single-mode optical fiber.

[0015] Furthermore, the preparation method of the acoustic signal amplifying diaphragm includes: adding an original CNT (carbon nanotube) solution with a mass concentration of 0.35wt.% to an SDS (sodium dodecyl sulfate) dispersion with a concentration of 0.72wt.%, mixing and filtering to prepare a rectangular original film, and then stretching it by 5% along the length direction after drying to form the acoustic signal amplifying diaphragm.

[0016] Furthermore, the size of the original film is 30 mm×50 mm.

[0017] Existing technologies often use ultrasound and ultra-high frequency (UHF) to detect partial discharge signals in gas-insulated electrical equipment. However, based on principle, only acoustic signals can effectively propagate to the outer surface of the equipment housing. Due to the waveform conversion effect of ultrasonic signals at multi-layer interfaces, the acoustic vibration energy that can be directly received is limited to a small area. The remaining energy is converted into weaker Lamb wave signals, which propagate far away along the cylinder. Because the discharge signal is composed of pulse packets of different frequencies, it has a guided wave dispersion effect. As the propagation distance increases, it becomes more difficult to distinguish it from background signals and interference, thus reducing detection reliability.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention arranges acoustic sensors at multiple points on gas-insulated electrical equipment, which can expand the comprehensiveness of early fault signal positioning and perceive faults in the early stages of their occurrence. By analyzing the signals of multiple groups of acoustic sensors with known distance differences, the position of the local discharge sound source can be quickly obtained, achieving rapid and accurate positioning of the local discharge fault point. By comparing with structural drawings, defect positioning at the component level can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described in further detail below with reference to the accompanying drawings.

[0020] Figure 1 : A schematic structural diagram of embodiment 1 of the present invention; Figure 2 : Flowchart of Example 2 of the present invention; Figure 3 : Flowchart of Example 3 of the present invention; Figure 4 : Flowchart of embodiment 4 of the present invention. DETAILED DESCRIPTION

[0021] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the examples and drawings, but the protection content of the present invention is not limited to the following examples. In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0022] Example 1: See Figure 1 This embodiment provides a system for locating partial discharges within gas-insulated electrical equipment. The system includes multiple acoustic signal amplifying diaphragms attached to the surface of the gas-insulated electrical equipment, acoustic sensors coupled one-to-one with the acoustic signal amplifying diaphragms, and a detection host connected to the acoustic sensors.

[0023] The acoustic signal amplifying diaphragm is used to amplify pulse signals and is rectangular in shape. The distribution direction of multiple acoustic signal amplifying diaphragms is parallel to the axis of the gas-insulated electrical equipment, and the length direction of the acoustic signal amplifying diaphragm is parallel to the axis of the gas-insulated electrical equipment.

[0024] In this embodiment, the detection host cooperates with the acoustic sensor to detect the acoustic signal generated by partial discharge using laser interference. Figure 1 As shown, the positioning system further includes a laser, a first fiber coupler, an acousto-optic modulator, a fiber amplifier, an optical circulator, a second fiber coupler, a photodetector and a single-mode optical fiber.

[0025] A continuous light source generated by a laser is transmitted to the first fiber coupler, where it is split into two paths with a 9:1 coupling ratio. 90% of the optical power enters an acousto-optic modulator (AOM), and the remaining 10% serves as local oscillator (LO) reference light. The AOM modulates the light into a periodic pulsed optical signal, which is amplified by a fiber amplifier and then coupled into a single-mode fiber via an optical circulator. The periodic pulsed optical signal propagates through the single-mode fiber, generating Rayleigh backscattered light that returns to the circulator. The Rayleigh scattered light signal is then transmitted from the circulator to the second fiber coupler, which simultaneously receives the LO reference light transmitted by the first fiber coupler. The coupling ratio of the second fiber coupler is 1:1. The Rayleigh scattered light and the LO reference light couple and interfere within the second fiber coupler. The photodetector detects the coherent optical signal, filters it, reduces noise, and converts it into an electrical signal for transmission to the detection host. The single-mode fiber is then optically connected to the acoustic sensor, allowing the detection host to detect the pulse signal generated by the acoustic sensor's vibration.

[0026] The detection host is used to identify partial discharge phenomena inside gas-insulated electrical equipment and locate the location of partial discharge by analyzing the acoustic sensor pulse signal.

[0027] The layout area of ​​the acoustic sensors should be more than 300 mm away from structures such as switch contacts and pot insulators where discharge is prone to occur, and the distribution direction of multiple acoustic sensors should be parallel to the axis of the gas-insulated electrical equipment.

[0028] The acoustic signal amplifying diaphragm is made of carbon nanotubes. Specifically, a 0.35 wt.% CNT (carbon nanotube) solution is added to a 0.72 wt.% SDS (sodium dodecyl sulfate) dispersion. After mixing and filtering, a rectangular raw film is prepared. After drying, the film is stretched 5% along its length to form the acoustic signal amplifying diaphragm. When used, the film is attached along the axial direction of the gas-insulated electrical equipment. Preferably, the raw film measures 30 mm x 50 mm.

[0029] The detection host has a sampling bit number of no less than 24 bits, a bandwidth of no less than 10Mb / s, and has a signal trigger mode.

[0030] Example 2: The purpose of this example is to provide a method for locating partial discharge inside a gas-insulated electrical device. The method is implemented using the positioning system described in Example 1. Figure 2 As shown, the positioning method includes: Step S11: Acquire pulse packets collected by two acoustic sensors.

[0031] The pulse packets collected by any two of the acoustic sensors are obtained using the positioning system described in Example 1. The collected pulse packets are a composite waveform with distinct characteristics, which is composed of multiple waves with different amplitudes and frequencies.

[0032] Step S12: obtaining the group velocity of the pulse packet based on the distance between the two acoustic sensors and the time difference between the two corresponding pulse packets.

[0033] Step S13: Acquire the propagation time of the pulse packet corresponding to the target acoustic sensor.

[0034] Specifically, this step includes: S131. Perform Fourier transform on the two pulse packets to obtain time domain waveforms of different frequencies in the two pulse packets.

[0035] The initial signal of the partial discharge signal wave is characterized by: .

[0036] In the frequency domain, it is expressed as ; spread for a period of time or a distance After that, it can be expressed as .

[0037] Considering the dispersion effect, the pulse packet collected by the acoustic sensor can be expressed as: .

[0038] Through Fourier transform, the time domain representation of different frequencies is obtained as follows: .

[0039] In the formula of this step, u is the time parameter of the pulse, f is the frequency, and s is the bandwidth.

[0040] Assume that the two selected acoustic sensors are A and B, and their corresponding pulse packets are P A and P B In this step, the pulse packet P A and pulse packet P B Perform Fourier transform to obtain the pulse packet P A and pulse packet P B Time domain waveforms of different frequencies.

[0041] S132. Select two typical frequency waves from each of the two pulse packets, and the waveforms of the typical frequency waves corresponding to different pulse packets are consistent.

[0042] In the pulse packet P A Two typical frequency waves W are selected A,X and W A,Y, in the pulse packet P B Select W A,X and W A,Y Two typical frequency waves W with the same waveform B,X and W B,Y Where W A,X and W B,X Can be regarded as waves of the same frequency, expressed as W X ;W A,Y and W B,Y Can be regarded as waves of the same frequency, expressed as W Y .

[0043] S133. Based on the time domain difference between two typical frequency waves in each pulse packet, obtain the speed difference of the typical frequency waves.

[0044] In the pulse packet P A In the example, two typical frequency waves W A,X and W A,Y With time domain difference T A ; In the pulse packet P B In the example, two typical frequency waves W B,X and W B,Y With time domain difference T B The typical frequency wave W X and W Y The speed difference can be expressed as , where L AB is the distance between acoustic sensor A and acoustic sensor B.

[0045] S134. Obtain the propagation time of the pulse packet based on the first wave position difference and the speed difference of the typical frequency wave.

[0046] The typical frequency waves of different frequencies in different pulse packets are emitted from the same source, and the propagation speed (phase velocity) is fixed. The propagation time of the pulse packet can be obtained through the first wave position difference and speed difference.

[0047] Step S14 : determining the partial discharge position according to the position of the target acoustic sensor based on the group velocity and propagation time of the pulse packet.

[0048] The product of the group velocity and propagation time of the pulse packet is the propagation distance. Based on the position of the target acoustic sensor, the location of the sound source, that is, the location of the partial discharge, can be determined.

[0049] Embodiment 3: The method for locating partial discharge inside a gas-insulated electrical device provided in this embodiment is a further improvement on the basis of Embodiment 2. The method further includes: Step S15 , repeatedly selecting two different acoustic sensors, and repeatedly executing S11 - S14 to localize the sound source, until all different pairwise combinations of acoustic sensors are selected.

[0050] Step S16 : determining the accurate partial discharge position based on the positioning results of multiple executions of S11 - S14 .

[0051] The results of multiple positioning are analyzed using methods such as averaging and statistics to determine the exact location of partial discharge.

[0052] Embodiment 4: The method for locating partial discharge inside a gas-insulated electrical device provided in this embodiment is a further improvement on the basis of Embodiment 2 or 3. The method further includes, before step S11: In step S10, a determination is first made as to whether the location of the partial discharge is within the area where the acoustic sensors are deployed. If not, the process proceeds to steps S11-S14 of Example 2, or steps S11-S16 of Example 3. If so, the time difference between the first pulse signals of the different acoustic sensors is multiplied by the speed of sound of the sulfur hexafluoride gas in the gas-insulated electrical equipment to determine the distance difference between the sound source and the different acoustic sensors. Triangulation is then performed based on the positional relationships between the different acoustic sensors to determine the location of the partial discharge.

[0053] The method for determining whether the partial discharge location is located in the layout area of ​​the acoustic sensors is as follows: when the waveforms collected by all acoustic sensors are the same and the amplitudes are close, it indicates that the sound signal is directly transmitted from the sulfur hexafluoride gas in the gas-insulated electrical equipment to the acoustic sensors, and the sound source is a direct signal source. In this case, the partial discharge location is determined to be located in the layout area of ​​the acoustic sensors.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limiting. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for locating partial discharge inside a gas-insulated electrical device, implemented using a positioning system, wherein the positioning system comprises a plurality of acoustic sensors disposed on the surface of the gas-insulated electrical device, wherein the acoustic sensors are arranged in a direction parallel to the axis of the gas-insulated electrical device; characterized in that: The positioning method includes: S11, obtaining pulse packets collected by two acoustic sensors; S12. Obtaining the group velocity of the pulse packet based on the distance between the two acoustic sensors and the time difference between the two corresponding pulse packets; S13, obtaining the propagation time of the pulse packet corresponding to one of the target acoustic sensors; S14. Determine a partial discharge location according to a location of a target acoustic sensor based on the group velocity and propagation time of the pulse packet.

2. The method for locating partial discharge inside gas-insulated electrical equipment according to claim 1, characterized in that: The positioning method further includes: S15. Repeatedly select two different acoustic sensors and repeat steps S11-S14 to localize the sound source until all different pairwise combinations of acoustic sensors are selected. S16. Determine the accurate location of the partial discharge based on the results of multiple sound source localizations.

3. The method for locating partial discharge inside gas-insulated electrical equipment according to claim 1 or 2, characterized in that: The positioning method further includes, before step S11: S10. Determine whether the partial discharge position is located in the arrangement area of ​​the acoustic sensor; if not, continue to execute subsequent steps; if so, directly locate the partial discharge position based on the sound velocity of sulfur hexafluoride gas in the gas-insulated electrical equipment and the position of the acoustic sensor.

4. The method for locating partial discharge inside gas-insulated electrical equipment according to claim 3, characterized in that: The method for determining whether a partial discharge position is located in an arrangement area of ​​acoustic sensors includes: when waveforms collected by all acoustic sensors are the same and have similar amplitudes, determining that the partial discharge position is located in the arrangement area of ​​the acoustic sensors.

5. The method for locating partial discharge inside gas-insulated electrical equipment according to claim 1, characterized in that: The method for obtaining the propagation time of the pulse packet corresponding to one of the target acoustic sensors includes: S131, performing Fourier transform on the two pulse packets to obtain time domain waveforms of different frequencies in the two pulse packets; S132. Select two typical frequency waves from each of the two pulse packets, and the waveforms of the typical frequency waves corresponding to different pulse packets are consistent; S133. Obtaining a velocity difference of the typical frequency waves based on a time domain difference between two typical frequency waves in each pulse packet; S134. Based on the first wave position difference and the velocity difference of the typical frequency wave, obtain the propagation time of the pulse packet corresponding to the target acoustic sensor.

6. The method for locating partial discharge inside gas-insulated electrical equipment according to claim 5, characterized in that: Methods for obtaining time domain waveforms of different frequencies in two pulse packets include: The initial signal of the partial discharge signal wave is characterized by: ； In the frequency domain, it is expressed as ; spread for a period of time or a distance After that, it is expressed as ; Considering the dispersion effect, the pulse packet collected by the acoustic sensor is expressed as: ； Through Fourier transform, the time domain representation of different frequencies is obtained as follows: ； Where u is the time parameter of the pulse, f is the frequency, and s is the bandwidth.

7. A system for locating partial discharge inside gas-insulated electrical equipment, characterized by: The device comprises a plurality of acoustic signal amplifying diaphragms attached to the surface of a gas-insulated electrical device, an acoustic sensor coupled one-to-one with the acoustic signal amplifying diaphragms, and a detection host connected to the acoustic sensor; The arrangement direction of the acoustic signal amplifying diaphragm and the arrangement direction of the acoustic sensor are both parallel to the axis of the gas-insulated electrical equipment; The detection host is used to locate the position of the partial discharge according to the pulse packet detected by the acoustic sensor; The acoustic signal amplifying diaphragm is used to amplify the pulse signal, and is rectangular in shape. The length direction of the acoustic signal amplifying diaphragm is parallel to the axis of the gas-insulated electrical equipment; The acoustic signal amplifying diaphragm is made of carbon nanotubes.

8. The system for locating partial discharge inside gas-insulated electrical equipment according to claim 7, characterized in that: It also includes a laser, a first fiber coupler, an acousto-optic modulator, a fiber amplifier, an optical circulator, and a single-mode optical fiber connected in sequence according to the laser transmission direction; Also included are a second fiber coupler and a photodetector of the laser connected in sequence according to the direction of laser transmission; The optical circulator and the first optical fiber coupler are optically connected to the second optical fiber coupler, and the photodetector is electrically connected to the detection host; The acoustic sensors are optically connected to the single-mode optical fiber.

9. The system for locating partial discharge inside gas-insulated electrical equipment according to claim 7, characterized in that: The preparation method of the acoustic signal amplifying diaphragm includes: adding an original CNT (carbon nanotube) solution with a mass concentration of 0.35wt.% to an SDS (sodium dodecyl sulfate) dispersion with a concentration of 0.72wt.%, mixing and filtering to prepare a rectangular original film, and then stretching it by 5% along the length direction after drying to form the acoustic signal amplifying diaphragm.

10. The system for locating partial discharge inside gas-insulated electrical equipment according to claim 9, characterized in that: The size of the original film is 30 mm×50 mm.

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