JP2013044616A - Partial discharge position locating method and partial discharge position locating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of a partial discharge position locating operation in a case a position of a partial discharge source of a stationary winding apparatus is inside the winding.SOLUTION: When at least one AE sensor is mounted on a tank wall of an oil-immersed transformer and also the position of the partial discharge source is located based on an AE signal output from the AE sensor by using a partial discharge current flowing through a neutral grounding line as a trigger, a decision is executed whether the discharge source is positioned inside the winding or on outer circumferential surface part of the winding by performing at least one decision among a first decision performed by whether a rise time α of a direct arrival wave of the AE signal is larger than a set value α* or not, and a second decision performed by whether a first wave of the direct arrival wave of the AE signal is a low frequency component or not, and a third decision same as the second decision based on such a waveform that the AE signal is subject to wavelet transformation. Based on these decision, at least three AE sensors are mounted and the position of the discharge source is located by obtaining a propagation distance from the discharge source to each AE sensor by changing a propagation speed of the discharge sound according to different propagation medium, when the discharge source exists inside the winding, based on an arrival time of the direct arrival wave of the AE signal to be output from each AE sensor and a delay of the arrival time of the high frequency component.

Description

  The present invention relates to a partial discharge position locating method and a partial discharge position locating apparatus, and more particularly to a technique for improving the localization accuracy of a partial discharge position of a stationary winding device having a winding such as a transformer.

  It is most appropriate for the insulation deterioration diagnosis of electrical equipment to measure a partial discharge (PD) generated as a precursor of dielectric breakdown. The partial discharge is detected by detecting a partial discharge by detecting an electromagnetic wave generated by the partial discharge (Patent Document 1), or by detecting a partial discharge based on a specific current that flows superimposed on the current of the electric device. (Patent Document 2) has been proposed. However, according to the method for detecting an electromagnetic wave described in Patent Document 1, it is necessary to incorporate an antenna for receiving the electromagnetic wave in advance in the diagnosis target device. Therefore, there is a problem that an unnecessary antenna must be installed and maintained in advance during normal operation. In this regard, according to the technique described in Patent Document 2, the partial discharge current component that flows while being superimposed on the current of the diagnosis target device is generally detected by mounting a clamp-type current detector on the ground line of the diagnosis target device. Therefore, it is not necessary to provide special equipment for the diagnosis target device. However, in the case of this document, there is a problem that the position where the partial discharge occurs cannot be determined.

  On the other hand, it has been proposed to specify a partial discharge and its discharge source using a plurality of acoustic sensors (hereinafter referred to as AE sensors) (Patent Document 3). According to this document, an acoustic signal (hereinafter referred to as an AE signal) in which three or more AE sensors are attached to a tank outer wall of a transformer to be diagnosed and partial discharge sound output from each AE sensor is converted into an electrical signal. ), And the generation of partial discharge and the position of the discharge source are specified based on the converted signal. That is, a partial discharge signal detected by each AE sensor is continuously recorded with the first signal obtained by detecting the partial discharge signal flowing through the neutral ground line of the transformer with the high frequency CT as a trigger signal. Then, the wavelet transform is performed on the partial discharge signal of each AE sensor, and a converted signal representing a change in the frequency component of the partial discharge signal is generated in correspondence with the elapsed time starting from the trigger signal. Next, based on the pattern of the generated wavelet transform signal, the arrival time at which the direct wave from the discharge source reaches each AE sensor is determined from the trigger signal as the starting point, and is released from the arrival time of each AE sensor and the propagation speed of the sound wave. The distance between the power source and each AE sensor is estimated, and the intersection of the spherical surfaces having the radius as the distance is specified as the discharge source.

JP 2009-25020 A JP 11-326429 A JP 2007-292700 A

  However, in the method described in Patent Document 3, since the propagation speed of the partial discharge sound is set uniformly, in the case of a structure in which different propagation media exist between the discharge source and each AE sensor, there is an error in estimation of the distance. There is a problem of being included. That is, when the object to be diagnosed is a winding device, it generally has a structure in which a winding wound around an iron core is housed in a metal container. In this case, since the space between the winding and the container is filled with an insulating material such as oil, air, and insulating gas, until the sound generated in the winding reaches each AE sensor from the discharge source. It passes through the winding part and the insulating material having different propagation speeds of the partial discharge sound. Therefore, the distance estimated based on the uniformly set propagation speed and propagation time includes an error, so that the accuracy of the position determination of the discharge source is reduced.

A first problem to be solved by the present invention is to be able to determine whether the position of a partial discharge source of a stationary winding device having a winding is the inside of the winding or the outer peripheral surface of the winding.
In addition to the first problem, the second problem to be solved by the present invention is to improve the accuracy of partial discharge position determination when the position of the partial discharge power source is inside the winding.

  In order to solve the first problem, a partial discharge position locating method according to the present invention is a part in which at least one AE sensor is mounted on an outer wall of a static winding device and a partial discharge of the static winding device is detected. A discharge detector is mounted, and an AE signal output from each of the AE sensors is input to an arithmetic processing unit using a detection signal of the partial discharge detector as a trigger, and the AE signal is recorded and based on the AE signal. In the partial discharge position locating method for locating the position of the partial discharge power source of the stationary winding device by calculation processing, the calculation processing for locating the position of the partial discharge power source of the stationary winding device includes first, second and second And determining whether the discharge source is located inside the winding of the stationary winding device or on the outer peripheral surface of the winding.

In the first determination process, the rising time α of the direct wave of the AE signal is measured, and whether or not the rising time α is equal to or greater than a set value α * is determined so that the discharge source is within the winding of the stationary winding device. Or whether it is located on the outer peripheral surface of the winding. Here, the rise time α is the time from the zero cross point to the peak of the first wave of the direct wave of the AE signal. Therefore, α is long when the first wave is a low-frequency component, and α is short when the first wave includes a high-frequency component.
The second determination process identifies a low frequency component and a high frequency component after arrival of the direct wave of the AE signal, and delays the arrival time of the high frequency component relative to the arrival time of the low frequency component (hereinafter, arrival time delay of the high frequency component). (Or simply abbreviated as arrival time delay)) Δt is measured, and based on whether the arrival time delay Δt is equal to or greater than a set value Δts, the discharge source is either inside the winding of the stationary winding device or the outer periphery of the winding. It is determined whether it is located in.
The third determination process obtains the arrival time delay Δt based on the converted waveform data obtained by wavelet transforming the AE signal, and determines whether the arrival time delay Δt is equal to or greater than a set value Δts. It is determined whether the power source is located inside the winding of the stationary winding device or on the outer peripheral surface of the winding.

  In this way, by detecting at least one of the first to third determination processes by detecting an AE signal by one AE sensor, whether the position of the discharge source is inside the winding or the outer peripheral surface of the winding. Can be determined. Then, based on the determination result, the arrival time T from when the detection signal of the partial discharge detector is input until the direct wave of the AE signal reaches each AE sensor, the set sound speed in the winding, The position of the discharge source is determined by calculating the distance from each AE sensor to the discharge source based on the set sound speed of the insulating material provided between the winding and the outer wall. In order to locate the position of the discharge source, it is necessary to mount at least three AE sensors on the outer wall of the stationary winding device.

  As described above, the partial discharge of the static winding device is caused by the partial discharge occurring inside the winding and the outer peripheral surface of the winding or the vicinity of the winding (hereinafter collectively referred to as the outer peripheral surface of the winding). It can be roughly divided into cases. The partial discharge sound generated on the outer peripheral surface of the winding propagates only through the insulating material such as oil, air, and insulating gas filled in the outer periphery of the winding and reaches the AE sensor. Depending on the sound speed of the material, the position of the discharge source can be determined without error.

  However, the partial discharge sound generated inside the winding propagates inside the winding to reach the outer peripheral surface of the winding, and further propagates through the insulating material to reach the AE sensor. According to the study by the present inventors, it has been found that the speed of sound (propagation speed) varies depending on the propagation medium and frequency. Therefore, even if the arrival time of the partial discharge sound generated inside the winding is simply measured, if the propagation medium in the propagation path of the partial discharge sound is different, the position of the discharge source cannot be accurately determined.

  Therefore, when the propagation of the partial discharge of the oil-filled transformer is analyzed by simulation, the sound speed inside the winding of the partial discharge generated sound varies greatly depending on the frequency, and the low frequency (for example, 30 kHz) is changed to the high frequency (for example, 300 kHz). It was found that the speed of sound inside the winding was faster than that. That is, the direct wave that reaches the AE sensor after the partial discharge occurs has many low-frequency components, and the high-frequency components arrive after a delay. The arrival time delay Δt of the high frequency component correlates with the propagation distance inside the winding of the partial discharge generated sound. Therefore, by identifying the frequency component of the AE signal, measuring the arrival time delay Δt of the high frequency component, analyzing the sound velocity data in the winding corresponding to the frequency component, and setting it in a data table or the like in advance. The propagation distance Lc from the discharge source to the outer peripheral surface of the winding can be estimated.

The arrival time T of the first wave of the low frequency component of the direct wave reaching the AE sensor with the trigger signal as the starting point is correlated with the propagation distance L from the discharge source to the AE sensor, and the propagation distance L This is the sum of the propagation distance Lc and the propagation distance Lo in oil, which is an insulating material. According to the analysis results, it was found that the sound speed V _L of the low frequency component is almost the same between the winding portion and the insulating material, and that there is no great difference from the sound speed V _HO of the high frequency component in the insulating material. Therefore, there is little error even if the sound speed V _L of the low frequency component is set to the set sound speed V _LS = V _HO (for example, 1400 m / s) based on analysis data described later. That is, the set sound velocity V _LS of the low frequency component in the winding portion and the insulating material is set in advance in a data table or the like, and the propagation distance L from the discharge source to the AE sensor is determined from the arrival time T and the set sound velocity V _LS. Can be estimated. Then, by subtracting the propagation distance Lc from the previously determined discharge source to the outer surface of the winding, the propagation distance Lo in the insulating material can be obtained separately.

  Here, a specific aspect of the first determination process is that when the rising time α of the direct wave is greater than or equal to the set value α *, the discharge source is located inside the winding of the stationary winding device, and the direct wave When the rise time α is less than the set value α *, it can be determined that the discharge source is located on the outer peripheral surface of the winding of the stationary winding device. Further, a specific aspect of the second or third determination process is that when the arrival time delay Δt is equal to or less than a set value Δts, the discharge source is located on the outer peripheral surface of the winding of the stationary winding device, and the arrival time delay When Δt exceeds the set value Δts, it can be determined that the discharge source is located inside the winding of the stationary winding device.

Further, a specific aspect of the positioning process is that when the discharge source is located on a winding outer peripheral surface portion of the stationary winding device, the arrival time T, the winding and the outer wall of the stationary winding device, The position of the discharge source can be determined by calculating the distance from each AE sensor to the discharge source based on the set sound speed of the insulating material provided between the two.
When the discharge source is located inside the winding of the stationary winding device, as described above, the arrival time delay Δt of the high frequency component of the AE signal is measured, and the winding set in advance in the data table or the like By multiplying the set sound velocity V _LS of the internal low frequency component, the propagation distance Lc from the discharge source to the outer peripheral surface of the winding is estimated. The arrival time T of the first wave of the low frequency component of the direct wave that reaches the AE sensor with the trigger signal as a starting point correlates with the propagation distance L (= Lc + Lo) from the discharge source to the AE sensor. Therefore, the propagation distance L from the discharge source to the AE sensor is estimated by multiplying the arrival time T by the set sound velocity V _LS of the low frequency component set in the data table or the like. Then, a propagation distance Lc from the previously determined discharge source to the outer peripheral surface of the winding is subtracted to obtain a propagation distance Lo in the insulating material.

  The position of the outer peripheral surface of the winding is obtained with the propagation distance Lo in the insulating material obtained in this way as the center of each AE sensor. This position is oval because the outer circumferential surface of the winding is cylindrical. Here, since the propagation path of the partial discharge sound is a straight line, the position of the discharge source is on the extended line of the long cone formed by connecting each AE sensor and an ellipse drawn on the outer peripheral surface of the winding. Therefore, an ellipse extending the propagation distance Lc is drawn on the extended line of the long cone, and the intersection of the ellipses of each AE sensor is the position of the discharge source to be obtained.

  In the location determination process, when the discharge source is located on the outer peripheral surface of the winding of the stationary winding device, the rationality of the position of the discharge source can be confirmed by further applying Snell's law. it can. Here, the rationality is that the incident angle of the sound wave formed by the propagation path in oil connecting the position of the determined discharge source and the AE sensor and the inner surface of the outer wall to which the AE sensor is attached is set in advance. If it is not within the range, the mounting position of the AE sensor is inappropriate, so the position is changed and the orientation is performed again.

  As described above, the present invention has been described by taking an oil-filled transformer as an example. However, the present invention is not limited to this, and can be applied to a gas-insulated transformer. Further, a stationary reactor such as a reactor having a winding or a shunt reactor is provided. Needless to say, the present invention can be applied to position location of partial discharge of a winding device. Moreover, the partial discharge position locating apparatus that implements the partial discharge position locating method of the present invention can be configured using a detachable AE sensor, a detachable partial discharge detector, a portable personal computer, and the like. Therefore, it is not necessary to always install the partial discharge position locating apparatus of the present invention in the stationary winding device to be diagnosed, and it is installed when necessary to perform partial discharge diagnosis and partial discharge position determination easily and accurately. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, while locating the position of the partial discharge source of the static winding apparatus provided with the coil | winding using an AE sensor, the positioning precision can be improved.

It is a flowchart which shows the procedure of the partial discharge position location method of one Embodiment of this invention. It is a block block diagram of the partial discharge position location apparatus of one Embodiment to which the partial discharge position location method of this invention is applied. It is a figure which shows the cross-sectional structure of an example of an oil-filled transformer which applies the partial discharge position location method of one Embodiment of this invention. It is a figure which shows the waveform figure of the AE signal and the waveform figure of a wavelet transformation signal when partial discharge generate | occur | produces in the winding outermost periphery surface part (tap winding outer side), ie, oil side, of an oil-filled transformer. It is a figure which shows the waveform figure of the AE signal when the partial discharge generate | occur | produces in the outer peripheral surface part of the primary winding of an oil-filled transformer, and the waveform figure of a wavelet transform signal. It is a figure which shows the waveform diagram of the AE signal when the partial discharge generate | occur | produces in the outer peripheral surface part of the secondary winding of an oil-filled transformer, and the waveform diagram of a wavelet transform signal. It is a figure which shows the waveform diagram of the AE signal when the partial discharge generate | occur | produces in the outer peripheral surface part of the tertiary winding of an oil-filled transformer, and the waveform diagram of a wavelet transform signal. It is a figure which shows the waveform figure of the AE signal when the partial discharge generate | occur | produces in the inner surface part (iron core side) of the tertiary winding of an oil-filled transformer, and the waveform figure of a wavelet transformation signal. It is a diagram which shows the analysis result with the arrival time when the sound of the discharge source in the perpendicular distance from the tank wall of the oil-filled transformer reaches the AE sensor. It is a figure explaining an example of partial discharge position location. It is a figure explaining an example of partial discharge position location. It is a figure explaining an example which applies the Semel's law and evaluates the validity of orientation.

  Hereinafter, an embodiment of a partial discharge position locating method of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart when the partial discharge position locating method of one embodiment of the present invention is applied to the partial discharge position locating of an oil-filled transformer, and FIG. 2 shows the partial discharge position locating method of one embodiment of FIG. It is a whole block diagram of the apparatus to implement. As shown in FIG. 2, the partial discharge position locating device of the present embodiment has at least three AE sensors 11A that can be detachably attached to a tank wall 2 that is an outer wall of an oil-filled transformer 1 that is a stationary winding device. , B, C. In addition, a high-frequency current transformer 12 that is detachably clamped to the neutral point grounding wire 3 of the oil-filled transformer 1 is provided. The high-frequency current transformer 12 is a partial discharge detector that detects a partial discharge current flowing through the ground wire 3. The AE sensors 11A, 11B, and 11C convert partial sound generated in the oil-filled transformer 1 into an AE signal that is an electrical signal. The AE signals output from the AE sensors 11A, 11B, and 11C are amplified by the amplifier 13 and input to the personal computer 15 constituting the arithmetic processing unit. The partial discharge detection signal that is the output of the high-frequency current transformer 12 is input to the personal computer 15 as a trigger signal for starting the partial discharge position locating method. As is well known, the personal computer 15 includes a central processing unit such as a CPU, a storage device, a liquid crystal display device, and input devices such as a keyboard and a mouse.

  FIG. 3 shows a cross-sectional view of the internal structure of the oil-filled transformer 1. The figure shows a cross-sectional structure from the axial center of the central portion in the axial direction of the winding portion of one phase to the tank wall 2. As shown in the figure, an iron core 31, a tertiary winding 32, a secondary winding 33, a primary winding 34, and a tap winding 35 are arranged from the center side of the winding portion via an insulating oil layer 36, respectively. . An insulating oil 37 is filled between the outer peripheral surface of the tap winding 35 and the inner surface of the tank wall 2. An AE sensor 11 is attached to the outer surface of the tank wall 2. For convenience of explanation, the position of the discharge source 38 is assumed by a circle in the figure.

The procedure for locating the partial discharge using the partial discharge position locating device of the embodiment configured as described above will be described along the flowchart shown in FIG. First, as shown in FIG. 2, the partial discharge position locator is installed, the personal computer 15 is started up, and the partial discharge position locating process is started.
(Step S1)
When a trigger signal is input from the high-frequency current transformer 12, the processing after step S2 is performed.
(Steps S2, S3)
An AE signal is acquired from each AE sensor 11 (A to C). When the AE signal is not acquired or when the signal intensity is insufficient, the attachment position of each AE sensor 11 (A to C) is changed until an AE signal with sufficient intensity is acquired.

(Step S4)
When an AE signal having an intensity exceeding a set threshold value is acquired, for example, the waveform of the AE signal as shown in the upper part of FIG. Note that this waveform data is digitally converted waveform data.
(Step S5)
Here, the partial discharge of the oil-filled transformer 1 that is a stationary winding device can be broadly divided into a partial discharge that occurs inside the winding and a case that occurs on the outer peripheral surface of the winding. Therefore, in step S5, it is determined whether the partial discharge discharge source 38 is inside the tap winding 35 or outside the tap winding 35 based on the acquired waveform data of the AE signal. This determination is performed by measuring the rise time α of the first wave of the direct wave of the AE signal (first determination process). That is, the principle of the present invention is based on the fact that when a partial discharge occurs inside the winding, the high-frequency component of the AE signal is propagated with a delay. Therefore, when the rise time α of the first wave of the direct wave is measured, the rise time α is shortened if the first wave contains a high-frequency component. On the other hand, if the first wave does not contain a high frequency component, the rise time α is long. Therefore, a set value α * (for example, 6 μsec) of the rise time is set, and if α ≧ α *, there are many low-frequency components, so that the discharge source 38 is located inside the winding. On the other hand, if α <α *, it can be estimated that the discharge source 38 is located on the outer peripheral surface portion of the tap winding 35.

  Incidentally, the AE signal waveform in FIG. 4 is an example in which the discharge source 38 is located on the outer peripheral surface portion of the tap winding 35. 5 is an example located on the outer peripheral surface portion of the primary winding 34, FIG. 6 is an example located on the outer peripheral surface portion of the secondary winding 33, and FIG. FIG. 8 shows an example in which the surface of the iron core 31 is located. In step S5, the first determination process determines whether the discharge source 38 is positioned inside the winding with the magnitude of the rise time α of the first wave of the direct wave of the AE signal, or the outer peripheral surface portion of the tap winding 35. It was identified whether it is located (in oil). Instead, the same determination can be made based on the waveform diagram of the AE signal shown in FIGS. 4 to 8 by the second determination process.

  In the second determination process, the low frequency component and the high frequency component after arrival of the direct wave of the AE signal are identified, and the arrival time delay Δt is measured. That is, as shown in FIGS. 4 to 8, let T be the arrival time at which the first wave of the direct wave of the AE signal arrives from time T = 0 when the trigger signal is input. Then, the first wave rises to the time range B through the time range A at which the first wave rises, and further shifts to the time range C. In particular, when comparing the time ranges A and B, the case of FIG. 4 is not so remarkable, but in the other examples of FIGS. 5 to 8, there are many low frequency components in the time range A and almost no high frequency components can be identified. This indicates that in the time range A, the propagation of the high frequency component is delayed. Since this arrival time delay Δt indicates that the high frequency component is delayed in the winding portion, the arrival time delay Δt correlates with the propagation distance of the winding portion. Therefore, based on whether the arrival time delay Δt is greater than or equal to a preset set value Δts, it can be determined whether the discharge source 38 is located inside the winding or on the outer peripheral surface of the tap winding.

  In addition, it can replace with a 1st determination process or a 2nd determination process, and can use the 3rd determination process determined based on the conversion waveform diagram which performed the wavelet transformation process mentioned later. Further, by performing the determination by performing two or three of the first to third determination processes, it is possible to improve the reliability of determining whether the discharge source 38 is in the winding or in the oil.

  Whether the discharge source 38 is located inside the winding or the outer peripheral surface portion (in oil) of the tap winding 35 can be identified by the determination in step S5 described above. In accordance with the result of this identification, the process shifts to the composite insulation discharge position orientation process start S10 or the oil discharge position orientation process start S20.

[When the position of the discharge source is located inside the winding part]
(Step S11)
Here, it is determined whether the position of the discharge source 38 is the central portion of the winding portion in the axial direction of the winding portion or the upper and lower portions of the winding. This determination is made based on the difference in the intensity and frequency component of the AE signal. The intensity of the AE signal is greatly attenuated when propagating through multiple composite insulations passing through a plurality of windings. Therefore, when the strength of the AE signal is reduced, it is determined that the AE signal is through multiple composite insulations. On the other hand, the attenuation is small when propagating through axial oil. Further, when propagating through the upper or lower portion of the winding without propagating through the winding portion, a small number of composite insulations are propagated, and in this case, the attenuation is small. Therefore, when propagating through the multiple composite insulation, when the frequency characteristics of the AE signal are observed, the peak frequency component due to the gap between the lines appears in the frequency characteristics of the AE signal. Is located at the center of the winding. On the other hand, when a small number of composite insulations are propagated, broad frequency characteristics appear, so that it can be judged that they are via a few composite insulations, and it is judged that the position of the discharge source 38 is located above or below the winding. . If it is determined in step S11 that the position of the discharge source 38 is at the center of the winding portion, the process proceeds to step S12. If it is determined that the position is the upper and lower portions of the winding, the process proceeds to step S15.

[When the discharge source is located in the center of the winding]
(Step S12)
Here, a known wavelet transform is performed on the AE signal. The converted waveform data obtained by the wavelet transform is as shown in the lower part of FIGS. That is, the converted waveform data obtained by the wavelet transform is waveform data including information on the elapsed time axis, frequency distribution, and AE signal intensity. 4 to 8, the horizontal axis represents elapsed time, the vertical axis represents frequency components, and the AE signal intensity is represented by shading. For example, in FIGS. 5 to 8, it can be seen that a portion surrounded by an ellipse 41 is a time zone in which a high-frequency component (for example, 100 kHz or more) does not reach the AE sensor. This point corresponds to the waveform diagram of the AE signal shown in the upper part of these drawings.

(Step S13)
Based on the converted waveform data obtained by the wavelet transform in step S12, the arrival time delay Δt of the high frequency component of the AE signal is obtained. If the arrival time delay Δt is obtained, it can be applied to the determination in step S5 as described above. That is, based on whether the arrival time delay Δt is greater than or equal to the set value Δts, it can be determined whether the discharge source 38 is located inside the winding or the outer peripheral surface of the winding.

(Step S14)
Here, the position of the discharge source 38 is determined based on the arrival time delay Δt of the high frequency component obtained in step S13. First, the arrival time T from when the trigger signal is input until the direct wave of the AE signal reaches each of the AE sensors 11A to 11C is measured. Next, based on the set sound speed in the winding and the set sound speed in oil as an insulating material, the distance from each AE sensor 11A to 11C to the discharge power source 38 is calculated to determine the position of the discharge power source.

  FIG. 9 shows sound velocity data obtained by analyzing propagation of partial discharge of the oil-filled transformer 1 by simulation. In the figure, the horizontal axis indicates the vertical distance from the tank wall 2 to the center of the oil-filled transformer 1, and the vertical axis indicates the arrival time (T) of the discharge sound from the discharge source 38. In the figure, the ◇ marks are measured values of low frequency (30 kHz), and the □ marks are measured values of high frequency (300 kHz). The line 52 in the figure is the sound speed data (approximately 1400 m / s) in the oil and winding of the discharge sound. A line 53 in the figure is sound speed data in the low frequency winding of the discharge sound, and a line 54 in the figure is sound speed data in the high frequency winding of the discharge sound. Thus, the sound speed inside the winding of the partial discharge generated sound varies greatly depending on the frequency. Using this difference in sound speed, the arrival time delay Δt correlates with the propagation distance inside the winding of the partial discharge generated sound. Therefore, as shown in FIG. 9, the sound velocity data in the inside of the winding is analyzed corresponding to the frequency component, and set in a data table or the like in advance, so that the propagation distance Lw from the discharge source to the outer circumferential surface of the winding is obtained. Can be estimated.

This will be specifically described below. The arrival time T of the first wave of the low-frequency component of the direct wave that reaches the AE sensors 11A to 11C starting from the trigger signal is correlated with the propagation distance L (= Lc + Lo) from the discharge source to the AE sensors 11A to 11C. Here, Lc is a propagation distance inside the winding, and Lo is a propagation distance in oil. Further, according to the sound speed data of FIG. 9, the sound speed of the low frequency component is substantially the same value (for example, 1400 m / s) in the winding and in the oil. Assuming that the sound speed of the low frequency component is the set sound speed V _LS , the propagation distance L from the discharge source 38 to the AE sensors 11A to 11C can be estimated by the following equation (1).
L = Lc + Lo = T × V _LS (1)
Incidentally, the propagation distance Lc inside the winding correlates with the arrival time delay Δt. Therefore, the propagation distance Lc can be obtained by the following expression (2) from the low-frequency set sound speed _VLS .
Lc = Δt × V _LS (2)
From the equations (1) and (2), the propagation distance Lo in oil is obtained by the following equation (3).
Lo = L−Lc = T × Vc−Δt × V _LS (3)

Thus, for each AE sensor 11 A- 11 C, determine the propagation distance _Lo A _{~Lo C} in oil, at a distance _Lo A _{~Lo C} until the outer peripheral surface of tap winding around the AE sensor 11 A- 11 C Ask for. As shown in FIGS. 10 and 11, since the outer peripheral surface of the tap winding is cylindrical, the positions of the distances Lo _{A to} Lo _C are located on the ellipses 56A, 56B,. . Here, FIG. 10 is a schematic view of the propagation path of the AE signal from the AE sensors 11 </ b> A and 11 </ b> B to the discharge source as viewed from the side of the oil-filled transformer 1. Further, the left diagram of FIG. 11 is a schematic diagram showing candidates for the location of the discharge source viewed from the AE sensors 11A and 11B in FIG. 10, and the right diagram shows the AE signal from the AE sensors 11A and 11B to the discharge source. It is the schematic diagram which looked at the propagation path of No. from the upper surface of the coil | winding of the oil-filled transformer.

  By the way, since the propagation path of the partial discharge sound is a straight line, the position of the discharge source 38 is a long cone formed by connecting the AE sensors 11A to 11C and the ellipses 56A, 56B. It is on the extension line. Therefore, the ellipses 57A, 57B,..., Extending the propagation distances LcA, LcB,... Are drawn on the extended line of the long cone, and the intersection points of the ellipses 57A, 57B,. Ask. If the intersection 58 of the ellipses 57A, 57B and 57C of at least three AE sensors 11A to 11C is obtained, the intersection 58 can be determined as the position of the discharge source 38 inside the winding. In this way, the position of the discharge source 38 inside the winding is determined and the process is terminated.

[When the position of the discharge source is above or below the winding part]
(Step S15)
If it is determined in step S11 that the position of the discharge source 38 is located above or below the winding portion, the strength of the AE signal and the arrival time T are confirmed in step S15.
(Step S16)
If the discharge source 38 is located above or below the winding part to support the determination at step S15, the process returns to step S3 so that a sufficiently strong AE signal can be obtained from above or below the winding part. In addition, the positions of the AE sensors 11A to 11C are changed, and the processes of steps S2 to S11 are repeated.
(Step S17)
Here, the intensity of the AE signal and the arrival time delay Δt are obtained, and partial discharge occurs in any part of the winding unit, that is, the tertiary winding 32, the secondary winding 33, the primary winding 34, and the tap winding 35. Determine if you did.
(Step S18)
Based on the results of determining which upper and lower portions of the windings are generated in units of windings, the position of the upper and lower portions of the windings is determined by the same processing based on the above formulas (1) to (3). Then, the position of the discharge source 38 is determined and the process is terminated.

[When the discharge source is located on the outer peripheral surface of the winding (in oil)]
If it is determined in step S5 that the discharge power source 38 is located on the outer peripheral surface portion of the tap winding 35, the process proceeds to step 20, and the processing in steps S21 to S23 is performed to determine the position of the discharge source in oil. Do.
(Step S21)
Here, wavelet transformation is performed on the AE signal to generate a wavelet transformation waveform signal.
(Step S22)
Based on the wavelet transform waveform signal, the arrival time T at which the discharge sound reaches the AE sensors 11A to 11C after the trigger signal is input is measured.
(Step S23)
The arrival time T is a time when only the AE sensors 11A to 11C reach the oil source 38 from the generation source 38, and therefore, based on the set sound velocity Vo (= V _LS ) in the oil, the following equation (4) Thus, the propagation distance Lo (LoA to LoC) from each of the AE sensors 11A to 11C to the discharge source 38 is obtained.
Lo = T × Vo (4)
Then, based on the obtained propagation distance Lo (LoA to LoC), the position of the discharge source 38 on the outer peripheral surface portion of the tap winding 35 is determined by the procedure described in FIG.

(Step S24)
Step S24 is an additional process to be selected as appropriate, and is a process for determining whether or not the position location of the discharge source 38 in step S23 is appropriate using Semel's law. That is, as shown in FIG. 12, when the propagation distance Lo in oil is obtained, the position of the discharge source on the outer peripheral surface of the tap winding is determined from the relationship with the position of the AE sensor 11, and thereby the propagation path of the discharge sound R is determined. An incident angle θi of a sound wave that is a solid angle formed by the propagation path R and the inner surface of the tank wall 2 to which the AE sensor 11 is attached is determined. When the incident angle θi is totally reflected by the transmittance T determined by the material (iron) of the tank wall 2, the discharge sound does not enter the AE sensor 11. Therefore, the position of the AE sensor 11 is changed to a position where the incident angle θi falls within the preset range θi *, and the position determination of the discharge source is performed again. That is, in the case of the propagation path R ₁ in FIG. 12, a part of the discharge sound is transmitted through the tank wall 2 and incident on the AE sensor 11 due to the transmittance T at the transmission angle θt. However, in the case of the propagation path R ₂ , the discharge sound is totally reflected on the inner surface of the tank wall 2 and does not pass through the tank wall 2, so that the discharge sound does not enter the AE sensor 11.

  The partial discharge position locating method according to the embodiment of the present invention has been described above, but the present invention is not limited to this. For example, in the embodiment of FIG. 1, an example in which the arrival time T and the arrival time delay Δt are measured based on the wavelet transform waveform is shown, but instead, the waveform of the AE signal described in the second determination process The arrival time T and the arrival time delay Δt can be measured directly. Therefore, the wavelet transform in step S12 can be omitted, the arrival time T and the arrival time delay Δt can be obtained from the waveform of the AE signal in step S13, and the orientation process in step S14 can be performed.

  Moreover, although the said embodiment demonstrated based on the example which applied this invention to the oil-filled transformer, this invention is not restricted to this, It can apply also to a gas insulation transformer. Furthermore, it goes without saying that the present invention can be applied to position determination of partial discharge of a stationary winding device such as a reactor having a winding.

  In addition, since the partial discharge position locating device of the above embodiment can be configured using a detachable AE sensor, a detachable partial discharge detector, a portable personal computer, etc., the stationary winding to be diagnosed It is not necessary to always attach to the device, and it is possible to easily perform partial discharge diagnosis and partial discharge position determination by attaching it when necessary.

DESCRIPTION OF SYMBOLS 1 Oil-filled transformer 2 Tank wall 3 Neutral point ground line 11 (11A-11C) AE sensor 12 High frequency current transformer 13 Amplifier 15 Personal computer

Claims (6)

At least one acoustic sensor is mounted on the outer wall of the stationary winding device, and a partial discharge detector for detecting a partial discharge of the stationary winding device is mounted. A partial discharge position for inputting an acoustic signal output from an acoustic sensor to an arithmetic processing unit, recording the acoustic signal, and locating a position of a partial discharge power source of the stationary winding device by arithmetic processing based on the acoustic signal In the orientation method,
The calculation processing for locating the partial discharge power source of the stationary winding device is:
Measure the rise time α of the direct wave of the acoustic signal, compare whether the rise time α is greater than or equal to a set value α *, and the discharge source is in the winding of the stationary winding device or the outer peripheral surface of the winding A first determination process for determining whether or not it is located;
The low frequency component and the high frequency component after arrival of the direct wave of the acoustic signal are identified, the arrival time delay Δt of the high frequency component with respect to the arrival time of the low frequency component is measured, and the arrival time delay Δt is equal to or greater than a set value Δts. A second determination process for determining whether the discharge source is located inside the winding of the stationary winding device or on the outer peripheral surface of the winding, based on whether or not
Based on the converted waveform data obtained by wavelet transform of the acoustic signal, the arrival time delay Δt of the high frequency component with respect to the arrival time of the low frequency component of the acoustic signal is obtained, and whether the arrival time delay Δt is equal to or greater than a set value Δts. And at least one determination process of a third determination process for determining whether the discharge source is located in the winding or the outer peripheral surface of the stationary winding device. Discharge location method.   Based on the determination result of whether the position of the discharge source obtained by executing at least one of the first to third determination processes is the inside of the winding or the outer peripheral surface of the winding, at least 3 on the outer wall of the stationary winding device Each of the acoustic sensors is mounted, and the arrival of the direct waves of the acoustic signals output from the acoustic sensors after the detection signals of the partial discharge detectors are input to the acoustic sensors. Based on the time T, the set sound speed in the winding, and the set sound speed of the insulating material provided between the winding and the outer wall, the distance from each acoustic sensor to the discharge source is calculated. The partial discharge position locating method according to claim 1, further comprising a position locating process for locating the position of the discharge source. In the first determination process, when the rise time α is equal to or greater than the set value α *, the discharge source is located inside the winding of the stationary winding device, and when the rise time α is less than the set value α *, Determine that the discharge source is located on the outer peripheral surface of the winding of the stationary winding device,
In the second or third determination process, when the arrival time delay Δt is equal to or less than a set value Δts, the discharge source is positioned on an outer peripheral surface portion of the winding of the stationary winding device, and the arrival time delay Δt is set to the first setting. When the value Δts is exceeded, it is determined that the discharge source is located inside the winding of the stationary winding device,
The positioning process is provided between each of the arrival times T and between the winding and the outer wall of the stationary winding device when the discharge source is located on the outer peripheral surface of the stationary winding device. Calculate the distance from each acoustic sensor to the discharge source based on the set sound speed of the insulating material to determine the position of the discharge source,
When the discharge source is located inside the winding of the stationary winding device, each of the arrival time delay Δt and the set sound velocity V _LS inside the winding from the discharge source to the outer peripheral surface of the winding. the propagation distance Lc estimated, the estimate of the respective propagation distance L from the discharge source from the set sound velocity V _LS with each arrival time T until the respective acoustic sensors, subtracting the respective propagation distance Lc from said respective propagation distance L 3. The partial discharge position according to claim 1, wherein each propagation distance Lo in the insulating material is obtained separately, and the position of the discharge source is determined based on each propagation distance Lo and Lc. Orientation method.   The positioning process is characterized in that when the discharge source is located on a winding outer peripheral surface portion of the stationary winding device, the rationality of the position of the discharge source is further confirmed by applying Snell's law. Item 4. The partial discharge position locating method according to any one of Items 1 to 3. From at least three acoustic sensors mounted on the outer wall of a stationary winding device, a high-frequency current transformer for detecting a partial discharge clamped to a neutral ground wire of the stationary winding device, and each acoustic sensor An arithmetic processing device that receives an output acoustic signal and an output signal of the high-frequency current transformer as a trigger signal, and the arithmetic processing device records the acoustic signal in a storage unit based on the trigger signal; In the partial discharge position locating device having a calculation processing unit for locating the position of the partial discharge power source of the stationary winding device based on the trigger signal and the acoustic signal,
The arithmetic processing unit measures the rise time α of the direct wave of the acoustic signal, and compares the rise time α with a set value α * or more to determine whether the discharge source is inside the winding of the stationary winding device. A first processing unit for determining whether the coil is located on the outer peripheral surface of the winding;
The low frequency component and the high frequency component after arrival of the direct wave of the acoustic signal are identified, the arrival time delay Δt of the high frequency component with respect to the arrival time of the low frequency component is measured, and the arrival time delay Δt is equal to or greater than a set value Δts. A second processing unit for determining whether the discharge source is located in a winding of the stationary winding device or a winding outer peripheral surface based on whether or not
Based on the converted waveform data obtained by wavelet transform of the acoustic signal, the arrival time delay Δt of the high frequency component with respect to the arrival time of the low frequency component of the acoustic signal is obtained, and whether the arrival time delay Δt is equal to or greater than a set value Δts. And at least one processing unit of a third processing unit for determining whether the discharge source is located in the winding or the outer peripheral surface of the stationary winding device,
Based on a determination result of whether the position of the discharge source obtained by executing at least one of the first to third processing units is inside the winding or the outer peripheral surface of the winding, the sound is generated after the trigger signal is input. Based on the arrival time T until the direct wave of the signal reaches each acoustic sensor, the set sound speed in the winding, and the set sound speed of the insulating material provided between the winding and the outer wall A partial discharge position locating apparatus comprising: a position locating processing unit that calculates a distance from each acoustic sensor to the discharge source to determine a position of the discharge source. In the first determination process, when the rise time α is equal to or greater than the set value α *, the discharge source is located inside the winding of the stationary winding device, and when the rise time α is less than the set value α *, Determine that the discharge source is located on the outer peripheral surface of the winding of the stationary winding device,
In the second or third determination process, when the arrival time delay Δt is equal to or less than a set value Δts, the discharge source is positioned on an outer peripheral surface portion of the winding of the stationary winding device, and the arrival time delay Δt is set to the first setting. When the value Δts is exceeded, it is determined that the discharge source is located inside the winding of the stationary winding device,
The position location processing unit is provided between the arrival time T and the winding and the outer wall of the stationary winding device when the discharge source is located on a winding outer peripheral surface portion of the stationary winding device. Calculate the distance from each acoustic sensor to the discharge source based on the set sound speed of the insulating material to determine the position of the discharge source,
When the discharge source is located inside the winding of the stationary winding device, the propagation distance from the discharge source to the outer peripheral surface of the winding from the arrival time delay Δt and the set sound velocity V _LS inside the winding Lc is estimated, the propagation distance L from the discharge source to the acoustic sensor is estimated from the arrival time T and the set sound speed V _LS, and the propagation distance Lc in the insulating material is subtracted from the propagation distance L. The partial discharge position locating device according to claim 5, wherein the position of the discharge source is determined based on the propagation distances Lo and Lc.

Images