JP6869499B2 - Diagnostic method and diagnostic equipment for transformer internal abnormalities and deterioration - Google Patents

Description

The present invention relates to a method and an apparatus capable of easily diagnosing an abnormality and deterioration inside a transformer without stopping an operating transformer.

As long-term operation of electric power equipment is required, further sophistication of abnormality diagnosis and deterioration diagnosis technology of electric power equipment is required.
In recent years, the application of frequency response analysis (FRA) to electrical signals has been studied for the diagnosis of transformers, but there is a problem that it is difficult to diagnose a transformer in operation. In addition, FRA is a method for detecting frequency characteristics such as winding impedance that changes due to deformation such as eccentricity and buckling of the winding and displacement, and from the viewpoint of preventive maintenance of equipment, before deformation and misalignment occur. A diagnostic method that captures the decrease in tightening force is desired.

As a machine equipment diagnosis, a method of measuring and analyzing mechanical vibration is generally used. This vibration analysis method is also called modal analysis, and mechanical vibration of transformers has been studied for a long time from the viewpoint of noise reduction, and in recent years, it has also been studied as a means for detecting looseness and deformation of windings.
The main mechanical vibration of a transformer is caused by the Lorentz force acting between the coils and the magnetostrictive phenomenon acting on the iron core, and has a frequency component that is an integral multiple of the power supply frequency. Therefore, until now, only changes in the vibration amplitude of an integral multiple of the power supply frequency (hereinafter referred to as the power supply system frequency) have been paid attention to in the transformer vibration data in operation.

The vibration of the iron core and windings (hereinafter referred to as the transformer contents), which are the sources of mechanical vibration, is via solid (from the top plate to the side plate of the transformer tank, from the bottom plate to the side plate) or liquid (insulating oil). Shake the wall of the transformer tank with the sensor attached. Therefore, when diagnosing an operating transformer from the outside, a sensor is installed on the wall surface of the transformer tank, but it has been reported that the vibration amplitude changes significantly if the mounting position of the sensor is slightly different on the wall surface of the tank. There is a problem that interferes with the diagnosis.

Several papers have reported the results of calculating the natural frequency of a transformer by regarding the winding as a spring-like structure in which copper wires and spacer press boards are alternately stacked. Similarly, the calculation result of the natural frequency of the iron core is also reported. Transformers are designed so that their natural frequencies (hereinafter referred to as mechanical frequencies) are different from the power supply system frequencies in order to avoid resonance phenomena.

Mechanical vibration is thought to reflect changes in the tightening force of the windings inside the transformer and displacement of the structures inside the transformer, and by monitoring the trends, it is possible to diagnose abnormalities and deterioration of the transformer. You can expect it.
From such a viewpoint, the present inventors have developed a technique for analyzing the vibration response of an operating transformer by using a vibration detector and a means by signal processing using an electronic circuit or software for the transformer vibration in the operating state. I am studying about. For example, the natural frequencies of various vibrations generated from an operating transformer due to the electromagnetic force generated by the energizing current loaded on the transformer are directly measured, or the exciting force due to the energizing current to the transformer. We are researching a technique to obtain the phase of transformer vibration based on the phase of
Further, Patent Document 1 below proposes a method in which an exciting inrush current (several times the rated current) is passed through a transformer, an impact force is applied by using the electromagnetic mechanical force generated by the exciting inrush current, and a method of diagnosing based on the generated sound is applied. doing.
The following Patent Document 2 describes a method of measuring the natural frequency of a transformer by vibrating an iron core and a winding by stepwise changing the excitation frequency in a predetermined frequency range. In the case of Patent Document 2, the transformer noise level for each excitation frequency is measured to obtain a frequency response function.

Japanese Patent No. 5691298 Japanese Unexamined Patent Publication No. 2008-82778

In the techniques described in Patent Documents 1 and 2, it is necessary to pass a current other than the load current to the transformer or change the excitation frequency, and there is a problem that the diagnosis cannot be made in the state of the operating transformer.
Next, according to the technique under study by the present inventors described above, the transformer vibration generated by the electromagnetic force generated by the energizing current and the applied voltage flowing through the operating transformer is measured. When the energizing current flowing through the transformer is small and the generated electromagnetic force is small, there is a problem that the vibration generated from the contents of the transformer is small and it is difficult to capture the vibration of the contents of the transformer on the tank wall surface.
In addition, depending on the application of the transformer, the electromagnetic force generated in the transformer contents may be increased by increasing the energizing current or the applied voltage, and the vibration of the transformer contents may be increased to increase the vibration of the tank wall surface. In some cases, the vibration can be increased, but in the case of a working transformer, there is a problem that it is difficult to easily change the energizing current or voltage for vibration measurement.

Therefore, an object of the present invention is that in a transformer diagnostic technique for diagnosing an abnormality or deterioration of a transformer in an operating state, the contents of the transformer are surely vibrated even if the energizing current or the applied voltage is small, and the peripheral wall of the tank is covered. It is to provide a method and a device capable of reliably capturing the vibration of the contents of the transformer with the installed vibration sensor and diagnosing the transformer based on the vibration.

The method for diagnosing internal abnormalities and deterioration of a transformer of the present invention is a method for diagnosing internal abnormalities and deterioration of a transformer including windings and iron cores constituting a coil body and a tank for accommodating them, and the tank is at the bottom. It is a box body composed of a wall, a peripheral wall, and a top plate, and the coil body is formed by winding a winding around an iron core extending in the vertical direction, and the coil body is arranged vertically. The coil body, which is tightened from above and below by a plate, is suspended from the top plate by a hanging metal fitting, and the transformer is housed inside the tank by energizing the windings. It is a mechanical vibration obtained by hitting the top plate of the tank with a hammer with a striking force that does not interfere with the operation of the transformer while the transformer is operating, and is vibration detection installed at a plurality of locations of the tank. Based on the mechanical vibration generated at each position of the vibration detector in the tank using the coil, the vibration peak is different from the vibration peak that is an integral multiple of the power supply frequency, which is the characteristic peak during the operation of the transformer. Observe a plurality of vibration peaks caused by the difference between the natural frequency at each position where the vibration detector is installed and the natural frequency inside the transformer, and among these multiple vibration peaks, the iron core is derived. The vibration peak, the vibration peak derived from the winding, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated are recognized separately, and the top plate, the iron core, and the winding are recognized separately. It is characterized in that the state of the transformer is analyzed by observing the change of the vibration peak derived from the structure in which the coils are integrated.
In the diagnostic method of the present invention, regarding the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated, the top plate, the iron core, and the iron core in a sound initial state transformer are described. It is characterized by analyzing the state of an operating transformer in comparison with a vibration peak derived from a structure in which windings are integrated .

In the diagnostic method of the present invention, an area is partitioned on a part of the peripheral wall of the tank of the transformer to be measured in the actual operating state, acceleration sensors are installed at a plurality of positions in the partition, and the top plate is hammered. The vibration obtained from the peripheral wall of the tank by tapping was measured as the output waveform of the accelerometer at each of a plurality of positions, and these output waveforms were subjected to high-speed Fourier conversion to plot the frequency on the horizontal axis and the amplitude on the vertical axis. It is preferable to analyze the peak of the natural frequency appearing in the waveform and compare the peak of the natural frequency obtained by the equivalent method with respect to the sound transformer to analyze the state of the operating transformer.

The diagnostic device of the present invention includes a winding, an iron core, and a tank for accommodating the windings and iron cores constituting the coil body, and the tank is a box body composed of a bottom wall, a peripheral wall, and a top plate, and extends in the vertical direction. The coil body is formed by winding a winding around the iron core, the coil body is tightened from above and below by a coil holding plate arranged vertically, and the tightened coil body is tightened by a hanging bracket to the top plate. a diagnosis apparatus for an internal fault and the deterioration of the transformer of the suspended housed inside the tank configuration, is mounted in a plurality of locations of said tank to a transformer in operation by the transformer occurs A plurality of vibration detectors having detection sensitivity for vibrations from a low frequency region to an audible sound region (1 Hz to 20 kHz), and the transformer while the winding is energized and the transformer is operated. Based on the mechanical vibration generated at each position of the vibration detector of the tank obtained by hitting the top plate of the tank with a hammer with a striking force that does not interfere with the operation of the transformer, at the characteristic peak during the operation of the transformer. A plurality of vibration peaks that are different from the vibration peaks that are integral multiples of a certain power supply frequency and are caused by the difference between the natural frequency at each position where the vibration detector is installed and the natural frequency inside the transformer. A structure in which the iron core-derived vibration peak, the winding-derived vibration peak, the top plate, the iron core, and the winding are integrated from among these plurality of vibration peaks. An arithmetic means for analyzing the state of the transformer by distinguishing and recognizing the vibration peaks derived from the transformer and observing the change of the vibration peaks derived from the structure in which the top plate, the iron core and the winding are integrated. It is characterized by being equipped with.
In the diagnostic apparatus of the present invention, information on the natural frequency of a sound transformer is recorded in the calculation means, and the top plate, the iron core, and the winding are integrated with each other detected by the vibration detector. It is preferable that the calculation means has an ability to compare the vibration peak of the above and the vibration peak derived from the structure in which the top plate, the iron core and the winding are integrated in the sound transformer.

In the diagnostic apparatus of the present invention, the information of the natural frequency of the sound transformer recorded in the calculation means is divided into a part of the peripheral wall of the tank in the operating state of the sound transformer, and the area is in the section. Accelerometers are installed at a plurality of positions, the top plate is hit with a hammer, the vibration obtained from the peripheral wall of the tank is measured as the output waveform of the acceleration sensor at each of the plurality of positions, and these output waveforms are subjected to high-speed Fourier conversion. This is the analysis result of the peak of the natural frequency that appears in the waveform obtained by plotting the frequency on the horizontal axis and the amplitude on the vertical axis, and the information on the natural frequency of the transformer to be measured is equivalent to this information. It is preferable that it is the analysis result of the peak of the natural frequency obtained from the operating transformer of the measurement target by the method.

The diagnostic method of the present invention is a method for diagnosing internal abnormalities and deterioration of a transformer provided with windings and iron cores constituting a coil body and a tank for accommodating them. The coil body is formed by winding a winding around an iron core extending in the vertical direction, and the coil body is tightened from the vertical direction by coil holding plates arranged vertically. The tightened coil body is suspended from the top plate by a hanging metal fitting, and the transformer is housed inside the tank. In contrast to the transformer, the building in which the transformer is installed is installed in the building. A vibration detector installed on the peripheral wall surface of the tank, which is a building that vibrates in response to vibrations from the building or due to environmental noise near the building, and the vibrations when the vibrations from this building are transmitted to the transformer. It is a vibration peak that is different from the vibration peak that is an integral multiple of the power supply frequency, which is the characteristic peak during operation of the transformer, and is the natural frequency at each position where the vibration detector is installed and the natural frequency inside the transformer. Observe a plurality of vibration peaks caused by the difference between the two, and among these plurality of vibration peaks, the vibration peak derived from the iron core, the vibration peak derived from the winding, and the top plate and the iron core. By distinguishing and recognizing the vibration peaks derived from the structure in which the windings are integrated and observing the changes in the vibration peaks derived from the structure in which the top plate, the iron core and the windings are integrated, the said It is characterized by analyzing the state of the transformer.
In the diagnostic method of the present invention, regarding the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated, the top plate, the iron core, and the iron core in a sound initial state transformer are described. It is possible to analyze the state of the transformer in operation by comparing it with the vibration peak derived from the structure in which the windings are integrated.

In the diagnostic method of the present invention, an area is partitioned on a part of the peripheral wall of the tank of the transformer to be measured in the actual operating state, acceleration sensors are installed at a plurality of positions in the partition, and based on the vibration of the building. The vibration obtained from the peripheral wall of the tank is measured as the output waveform of the accelerometer at each of a plurality of positions, and these output waveforms are subjected to high-speed Fourier conversion to plot the frequency on the horizontal axis and the amplitude on the vertical axis. It is preferable to analyze the peak of the natural frequency appearing in the above and analyze the state of the operating transformer by comparing with the peak of the natural frequency obtained by the equivalent method for the sound transformer.

The diagnostic device for internal abnormality and deterioration of a transformer of the present invention includes a winding, an iron core, and a tank for accommodating them, and the tank is a box body including a bottom wall, a peripheral wall, and a top plate. The coil body is formed by winding a winding around an iron core extending in the vertical direction, and the coil body is tightened from the vertical direction by coil holding plates arranged vertically, and the coil body is tightened. a suspended in diagnostic device in the abnormal and degradation of the transformer of the receiving configurations inside the tank to the top plate by the hanger, to transformer is installed in a building is operational A vibration detector that is mounted at a plurality of locations in the tank and has detection sensitivity for vibrations from a low frequency region to an audible sound region (1 Hz to 20 kHz) generated by the transformer, and a detection signal from the vibration detector. The mechanical vibration based on the phase of the transformer vibration including the vibration transmitted from the building to the transformer in operation is obtained and analyzed, and the machine generated at each position of the vibration detector in the tank. Based on the target vibration, the vibration peak is different from the vibration peak that is an integral multiple of the power supply frequency, which is the characteristic peak during operation of the transformer, and the natural frequency at each vibration detector installation position and the natural vibration inside the transformer. An analyzer that observes a plurality of vibration peaks caused by different numbers, a vibration peak derived from the iron core, a vibration peak derived from the winding, and the top plate from among the plurality of vibration peaks. And the vibration peak derived from the structure in which the iron core and the winding are integrated are recognized separately, and the change in the vibration peak derived from the structure in which the top plate, the iron core and the winding are integrated is observed. This is characterized by being provided with a calculation means for analyzing the state of the transformer.
In the diagnostic apparatus of the present invention, information on the natural frequency of a sound transformer is recorded in the calculation means, and the top plate, the iron core, and the winding are integrated with each other detected by the vibration detector. It is characterized in that the calculation means has an ability to compare the vibration peak of the above and the vibration peak derived from the structure in which the top plate, the iron core and the winding are integrated in the sound transformer.

In the diagnostic apparatus of the present invention, the information on the natural frequency of the sound transformer recorded in the calculation means is divided into a part of the peripheral wall of the tank in the operating state of the sound transformer, and the area is in the section. Accelerometers are installed at a plurality of positions, the vibration obtained from the peripheral wall of the tank based on the vibration of the building is measured as the output waveform of the acceleration sensor at each of the plurality of positions, and these output waveforms are subjected to high-speed Fourier conversion. This is the analysis result of the peak of the natural frequency that appears in the waveform obtained by plotting the frequency on the horizontal axis and the amplitude on the vertical axis. It is preferable that this is the analysis result of the peak of the natural frequency obtained from the operating transformer of the measurement target.

According to the diagnostic method and the diagnostic apparatus of the present invention, a structure in which a top plate, an iron core, and a winding are integrated by using an impact test or using environmental vibration without stopping an operating transformer. It will be possible to distinguish the vibration peaks of the above from other vibration peaks, grasp and observe them, and make an external diagnosis of internal abnormalities and deterioration while in the operating state.
Further, in the conventional frequency response analysis in electrical vibration, an abnormality is diagnosed after the iron core and the coil actually shift, but according to the diagnostic method and the diagnostic apparatus according to the present invention, the coil winding is tightened. Since it is possible to diagnose natural vibrations caused by force reduction, it is a diagnostic method that can grasp abnormalities before actual deviation occurs, and it is also an excellent diagnostic method and diagnostic device as a preventive maintenance method for transformers. is there.

The block diagram which shows 1st Embodiment of the apparatus which diagnoses abnormality and deterioration of the transformer which concerns on this invention. The perspective view which shows the outline of the tank of the transformer applied to the test. The structure of the coil body, winding, iron core, yoke, yoke holder, hanging metal fitting, etc. housed in the tank of the transformer shown in FIG. 2 is shown. FIG. 2A is a plan view and FIG. 2B is a side view. An explanatory view showing a division position where an acceleration sensor is attached to the upper right wall of the tank of the transformer shown in FIG. An example of the vibration mode shown by the iron core housed in the tank of the transformer shown in FIG. 2 is shown, (A) is a perspective view showing a twisting mode, (B) is a perspective view showing a bending mode 1, (C). ) Is a perspective view showing the bending mode 2. A graph showing the results of vibration measurement for a working transformer tank and the vibration measurement results when the side surface of the transformer tank is hit with a hammer. Waterfall diagram of vibration data before and after stopping obtained when the exciting current of a transformer operating under no load is turned off and the transformer is stopped. The graph which shows the result of the vibration measurement on the concrete stand under the transformer and the result of the vibration measurement on the floor of the separate room adjacent to the transformer installation room in comparison with each other while the transformer is operating at a load factor of 10%. In the building where the transformer is installed, the vibration measurement result during the transformer operation (no load) measured by the acceleration sensor attached to the wall surface facing the side wall of the transformer and the vibration measurement result measured by the sensor after the transformer is stopped are shown. Graph shown in comparison. A waterfall diagram showing the measurement results of wall vibration. The graph which shows the test result (FFT result) when the transformer was disassembled, the sensor was installed on the top plate, and the top plate was hit with a hammer. The graph which shows the test result (FFT result) at the time of hitting with a hammer on the side wall surface of the tank which stopped the transformer before dismantling. The graph which shows the test result (FFT result) when the transformer was disassembled, the sensor was installed on the top plate, and the iron core was hit with a hammer. The graph which shows the test result (FFT result) when the transformer was disassembled, the sensor was installed on the top plate, and the winding was hit with a hammer. The graph which shows the test result (FFT result) at the time of disassembling the transformer, removing the top plate and the fastener, installing the sensor directly on a winding, and hitting the winding with a hammer. The graph which shows the result of averaging the data which performed the fast Fourier transform (FFT transform) of the measurement result in the actual operation state about 32 points of the side surface of the tank of a transformer for each frequency. The graph which shows the test result of the graph shown in FIG. 11 by enlarging the horizontal axis frequency (0 to 120 Hz). A graph showing the test results of the graph shown in FIG. 13 with the horizontal axis frequency (0 to 120 Hz) enlarged. The graph which shows the test result of the graph shown in FIG. 14 by enlarging the horizontal axis frequency (0 to 120 Hz).

<First Embodiment>
Hereinafter, the method for diagnosing abnormality and deterioration of the transformer and the first embodiment of the diagnostic apparatus according to the present invention will be described with reference to the drawings, taking the case of an oil-immersed transformer as an example.
FIG. 1 is a configuration diagram showing a first embodiment of an apparatus for diagnosing an abnormality and deterioration of a transformer, and the diagnostic apparatus A of the present embodiment is an oil-immersed transformer 1 having a structure shown in FIGS. 2 and 3 as an example. It is a device for diagnosing abnormalities and deterioration of.
In the transformer 1 of this example, three winding-type coil bodies 3 shown in FIG. 3 are housed inside the metal tank 31 shown in FIG. 2 with their central axes facing up and down, and inside the tank 31. It becomes filled with insulating oil. An iron core 5 made of a magnetic material such as a silicon steel plate is inserted into the center of each coil body 3, and each iron core 5 is integrated with a rod-shaped yoke 6 made of a magnetic material in which silicon steel plates or the like are laminated at the upper and lower ends of each. It has been transformed. Three coil bodies 3 are formed by providing windings 4 around each of the three iron cores 5 (tripod iron cores).
Since the transformer 1 of this embodiment is for three-phase alternating current, the three coil bodies 3 form three phases of U phase, V phase, and W phase, respectively, but the coil body 3 housed in the transformer. The number of the above is not limited to three, and it goes without saying that the present embodiment can be applied to any number of transformers having coil bodies.

As shown in FIG. 3, in the transformer 1, coil holding plates 7 are provided so as to individually sandwich the three coil bodies 3 from above and below, and the coil holding plates 7 and 7 are penetrated and tightened. A plurality of axial tightening bolts 8 are provided. In this embodiment, three axial tightening bolts 8 are provided on both sides in the thickness direction of the coil body 3 in which three are arranged in parallel, and the lower end of the axial tightening bolt 8 penetrates the lower coil holding plate 7. The upper end of the axial tightening bolt 8 penetrates the upper coil holding plate 7 and extends to the upper side thereof. A threaded portion (not shown) is formed in a portion where the axial tightening bolt 8 penetrates the coil holding plate 7, and the coil holding plate facing vertically is opposed to the threaded portion by adjusting the screwing condition of the axial tightening bolt 8. The interval between 7 and 7 can be adjusted. As a result, a predetermined tightening force is applied to the coil body 3 from the vertical direction by the coil holding plates 7 and 7 facing vertically. The coil holding plate 7 is made of wood such as a press board.

As shown in FIG. 3 (A), the upper yoke 6 is sandwiched between the upper yoke holding metal fittings 10 and 10 arranged on both sides in the thickness direction (both sides in the vertical direction of FIG. 3 (A)) and binds them together. It is restrained by the upper yoke holding bolt 11 for the purpose, and a tightening force is applied. Further, a strip-shaped hanging metal fitting 12 is attached to both end sides (left and right end sides in FIG. 3) of the upper yoke holding metal fittings 10 and 10, and the coil body 3, the iron core 5, the yoke 6 and the like are integrated. It is suspended from the top plate 31A of the tank 31 by the hanging metal fitting 12.
Further, the lower yoke 6 is also restrained by the lower holding metal fitting 10 and the lower yoke holding bolt (not shown) like the upper yoke 6.

In the present embodiment, the coil body 3 is composed of an outer coil and an inner coil (not shown), and the outer coil (primary coil) has an outer winding (primary winding) and an insulating spacer (solid insulator) laminated vertically. It is composed of a laminate sandwiched between an upper insulator and a lower insulator. The inner coil (secondary coil) of the coil body 3 is configured by sandwiching a laminate in which an inner winding (secondary winding) and an insulating spacer (solid insulator) are laminated vertically between an upper insulator and a lower insulator. ing.
Due to the above-mentioned structure, a tightening force is applied to each coil body 3 from above and below by the coil holding plate 7, and in this tightened state, the coil body 3 is suspended in the tank 31 and immersed in insulating oil (not shown).

Since the transformer 1 having the above configuration is used for stepping down a high voltage sent from a transmission line or the like near a power user, a current is constantly flowing through the winding of the coil body 3. Since an electromagnetic force acts by passing an electric current through the winding, an electromagnetic force acts on the coil body 3 and the iron core 5, and these vibrate. This vibration is transmitted to the entire transformer 1, and is also transmitted to the top plate 31A, the peripheral wall 31B, and the bottom wall 31D of the tank 31 shown in FIG.
In addition, when a short circuit accident or a ground fault occurs in a transmission line, a large current of 10 to several tens of times the rated load current may flow in the winding of the transformer 1, and electromagnetic force and vibration exceeding the standard may occur. May act on the transformer 1.
Due to these various factors, heating and other effects, the insulating oil of the transformer 1 gradually deteriorates over time. Further, since the insulating spacer of the coil body 3 on which the tightening force and vibration always act is made of cellulose fiber, the insulating spacer may also deteriorate, and the winding of the coil body 3 may also be caused by a short circuit accident or a ground fault. Unexpected deterioration may occur. Further, the coil holding plate 7 made of a press board may be partially deteriorated.
As described above, the transformer 1 may be deteriorated in each part by being used for a long period of time.

The abnormality and deterioration diagnostic device A of the transformer 1 shown in FIG. 1 receives and amplifies the vibration detector (vibration sensor) 22 arranged along the transformer 1 and the output signal from the vibration detector 22. The amplifier (vibration sensor amplifier) 25, the signal analyzer (spectrum and phase difference detector) 26 that receives the output from the amplifier 25, and the arithmetic unit 27 connected to the signal analyzer 26 are mainly configured. In the diagnostic apparatus A, a voltmeter (energized voltmeter) 23 for measuring the voltage for energizing the transformer 31 and a signal analyzer 26 are connected to the voltmeter 23 via an amplifier (energized voltage amplifier) 24.

The vibration of the transformer 1 is analyzed by the procedure described below using the diagnostic device A shown in FIG. 1. The interpretation of the vibration principle assumed when the diagnostic device A of the present embodiment diagnoses abnormality and deterioration is as follows. Will be described in order.
The propagation path of the vibration generated by the transformer 1 in the operating state is estimated as follows.
The primary causes of vibration are the vibration of the iron core 5 and the vibration of the winding 4 of the coil body 3, and the vibrations of both are the coil holding plate (press board) 7, the axial tightening bolt 8, the upper yoke holding metal fitting 10, and the suspension. It is propagated to the tank 31 via the metal fitting 12 and the like. Therefore, the vibration of the tank 31 is a combination of the vibration of the iron core 5, the vibration of the winding 4, the vibration of the tank 31 itself, and the following vibration.
The following vibrations are, for example, when the building in which the transformer 1 is installed has a mechanical device or other vibration source, or when there is a vibration source that adds vibration to the building around the building, the tank 31 On the other hand, the vibration from these vibration sources is a vibration component transmitted through the building.
Further, as another example, it is a vibration component generated by an impact test described later in which a striking force is applied to the top plate 31A of the transformer 1 by a hammer with a striking force that does not interfere with the operation of the transformer 1. The transformer 1 is usually equipped with a sensor for detecting an impact, and is provided with a safety device such as warning an abnormality of the transformer 1 when a vibration exceeding a specified value is applied. Since there is a problem if the hammer gives an impact that activates this safety device, the impact applied to the transformer 1 by the hammer is an impact force of about 50N to 500N, preferably an impact force of about 100N to 300N. Is preferable.

As will be described later, the present inventors took advantage of the opportunity to dismantle the transformer after 41 years in actual operation, and in the building where the transformer was installed, vibrations added from the surrounding vibration sources and the contents of the transformer were generated. The vibration was measured and the vibration was analyzed. Further, in parallel with this vibration analysis, the vibration component generated when the top plate 31A of the tank 31 was hit with a hammer was measured and analyzed.
The outline of the tank 31 used for the vibration analysis is shown in FIG. However, FIG. 2 omits bushings and wiring for inputting and outputting electric power to the transformer 1, and shows only an outline of the tank 31.
This tank 31 is a rectangular parallelepiped hollow container made of steel plate having a width of 2200 mm, a height of 2000 mm, and a depth of 800 mm. 32 and 33 are provided.
The portion of the peripheral wall of the tank 31 above the reinforcing stay 32 is composed of the upper peripheral wall 31a, the portion of the peripheral wall of the tank 31 below the reinforcing stay 32 is composed of the central peripheral wall 31b, and the peripheral wall of the transformer tank 31 is composed of the reinforcing stay 33. The lower part is composed of the lower peripheral wall 31c.
Since the portions of the reinforcing stays 32 and 33 in the tank 31 are positions where vibration is restricted, these can be excluded, and the following 18 positions can be candidates as positions for mounting the vibration sensor 22 and measuring vibration. ..

Vibration can be measured by attaching vibration sensors 22 to each of the positions of the tank 31 where the numbers 1 to 16 are surrounded by a circle in FIG. 2. The position of the number 1 surrounded by a circle indicates the left side wall surface of the upper peripheral wall 31a, and the position of the number 2 surrounded by a circle mark corresponds to the left end side of the front wall of the upper peripheral wall 31a (about 40 cm from the left end of the front wall). The position of the number 3 surrounded by a circle indicates the position corresponding to the right end side of the front wall of the upper peripheral wall 31a (near the position about 40 cm away from the right end of the front wall). The position of the number 4 surrounded by a circle indicates the right side wall surface of the upper peripheral wall 31a, and the position of the number 5 surrounded by a circle mark corresponds to the right end side of the back wall of the upper peripheral wall 31a (about 40 cm from the right end of the back wall). The position of the number 6 surrounded by a circle indicates the position corresponding to the left end side of the back wall of the upper peripheral wall 31a (near the position about 40 cm away from the left end of the back wall).

As illustrated here, the positions where the vibration sensor 22 is attached are the positions of the numbers 7, 8, 9, and 10 circled on the central peripheral wall 31b below the reinforcing stay 32 and the lower peripheral wall 31c below the reinforcing stay 33. The position may be any of the numbers 13, 14, 15, and 16 surrounded by a circle. The mounting position of the central peripheral wall 31b on the back wall side and the mounting position of the lower peripheral wall 31c on the back wall side are omitted because they cannot be shown in FIG. It is set on the back wall side of the central peripheral wall 31b and the back wall side of the lower peripheral wall 31c, respectively. Therefore, 18 locations can be selected as candidates.
In these vibration sensor mounting candidate positions, in the test described later, a vibration sensor was installed on the right side wall surface of the upper peripheral wall 31a corresponding to the position where the number 4 is surrounded by a circle in the tank 31, and the vibration was measured.

As shown in FIG. 3, inside the transformer 31 tested in this example, a coil body 3 is formed by applying a primary winding and a secondary winding to three iron cores 5, and these are placed above and below. The structure is such that the coils are sandwiched between the coil holding plates 7 and 7 and tightened with the axial tightening bolts 8, and the upper and lower yokes 6 are restrained by the yoke holding metal fittings 11 and 11.

It can be assumed that the iron core 5 takes three types of vibration modes: the twist mode shown in FIG. 5 (A), the bending mode 1 shown in FIG. 5 (B), and the bending mode 2 shown in FIG. 5 (C). The mode analysis shown in FIG. 5 is based on "Natural vibration characteristics of transformer core" by Sueyoshi Mizuno et al. (2013, IEEJ National Convention 5-195).

In FIG. 5, for the sake of simplification of the description, with respect to the structure consisting of the three coil bodies 3, their iron cores 5, and the upper and lower yokes 6, the three leg portions 35 are the upper and lower yoke portions 36, 37. It is drawn as an iron core 38 with a well girder structure connected by. Further, in FIG. 5, the description of the winding composed of the primary side winding and the secondary side winding wound around the leg portion 35 is omitted.

In the case of the twist mode transformer shown in FIG. 5 (A), the iron core vibration is captured on the tank wall surface by installing a vibration sensor at a position surrounded by circles the numbers 2, 3, 5, and 6 shown in FIG. Is thought to be possible. In that case, the positions of the numbers 2 and 3 are in the opposite direction, the positions of the numbers 5 and 6 are in the opposite direction, the positions of the numbers 2 and 6 are in the same direction, and the positions of the numbers 3 and 5 are in the same direction. If it can be confirmed that it is displaced, it can be seen that the iron core is oscillating in the torsion mode.
Similarly, as shown in FIG. 5B, if the vibration sensors are installed at the positions of the numbers 8, 9, 11 and 12 and the displacement is confirmed, it can be seen that the vibration is performed in the mode 1.
Similarly, if the vibration sensors are installed at the positions 7 and 10 as shown in FIG. 5C and the displacement is confirmed, it can be seen that the vibration is performed in the mode 2.

If the vibration mode can be identified as the natural frequency of the iron core, the tightening force of the iron core can be calculated from the natural frequency. However, if the tightening force of the iron core varies, the peak of natural vibration spreads. On the contrary, it is also possible to evaluate the variation of the tightening force from the spread of the natural frequency, for example, the half width. Similar evaluation is possible when the natural vibration peak of the winding has a spread. Widening the peak width is related to the deterioration of the iron core or winding, but how much the peak width becomes the threshold value for deterioration diagnosis depends on the design of each transformer, so it is necessary to decide for each transformer.

In the present embodiment, on the right side wall surface of the upper peripheral wall 31a of the tank 1, the left and right directions of the right side wall surface are divided into 15 as shown in FIG. 4, 1A, 2A, ... 15A, and the vertical direction of the right side surface is 1A. An impact test was conducted in which the vibration sensor was divided into seven parts such as 1B and 1G, one vibration sensor was installed at the position of 3C, for example, and the position of 4C on the right side was hit with a hammer to give vibration. In the tank 1, the size of the right side wall surface of the upper peripheral wall 31a is about 80 cm in width and 40 cm in length, and the divided width is set to 5 cm in both length and width.
Further, the vibration sensor 22 may be installed at the position of 13F and the position of 13E may be hit with a hammer as an impact test. The position where the vibration sensor is attached and the position where the hammer is struck may be any position as long as the vibration of the tank 31 can be satisfactorily picked up, and is not limited to the position shown in FIG.

In the following tests, the measurement was performed by a PCB accelerometer (sensitivity 50 mV / (m / s ² ), frequency range 0.4 to 4 kHz), an OROS data logger (sampling frequency 100 kS / s), and a PCB. The following measurements and impact tests were performed using the impact hammer (excitation force 100 to 200 N, frequency range 0 to 3 kHz). The accelerometer measured the acceleration in the out-of-installation direction. The transformer 1 used for this measurement is a three-phase transformer having a rated capacity of 10 MVA, a primary side voltage of 11 kV / a secondary side voltage of 3.45 kV, a frequency of 60 Hz, an oil capacity of 5300 L, and a 41-year operation. Further, the transformer 1 is installed on a concrete stand provided on the floor of one room of the building.

<Measurement and test items>
(1) Tank side impact test An impact test was performed on the right wall surface of the upper peripheral wall 31a with respect to the transformer 31 operating at a load factor of about 10%. Two sensors 22 were used and installed at positions 3C and 13F shown in FIG. Two points, position 4C and position 13E, were hit.
(2) Measurement of actual operating vibration on the side surface of the tank The actual operating vibration of the right wall surface of the upper peripheral wall 31a was measured with respect to the transformer 31 operating at a load factor of about 10%. For odd columns (1,3,5,7,9,11,13,15), the sensors are moved sequentially using two sensors at a total of 8 x 4 = 32 locations in rows A, C, E, and G. Then, each point was measured for 10 seconds.
(3) Measurement when the side of the tank is stopped The exciting current of the transformer 31 operating in the no-load state was cut off, and the transformer 31 was stopped. The actual operating vibration of the right wall surface of the upper peripheral wall 31a was measured for 120 seconds including the timing of stopping the transformer.

(4) Ambient noise measurement (environmental vibration measurement)
Accelerometers are placed on the concrete stand in the transformer installation room where the transformer 1 is installed, the floor of the separate room next to the building, and the wall surface of the transformer installation room facing the right wall surface of the upper peripheral wall 31a. 22 was installed and each vibration was measured.
(5) Impact test at the time of dismantling The transformer 31 was dismantled, the top plate 31A and the contents of the transformer were suspended, and an impact test was performed on the contents of the transformer. Accelerometers are installed on the top plate 31A at three locations (near the upper part of each coil body 3 of U phase, V phase, and W phase), and the top plate 31A is installed at two locations (between UV and VW) and the iron core 8. Vibration was measured by hammering the points and 9 winding points with an impact hammer.
After that, remove all the axial tightening bolts 8 that connect the top plate 31A, the iron core 5, and the winding, remove the top plate 31A, and place the sensor 22 on the press board above the winding at three locations (U phase, V phase, (W phase) was installed, and the windings were hammered at 9 places to measure the vibration. The winding point positions are the upper surface (side surface of the coil holding plate 7) of each of the U-phase, V-phase, and W-phase coil bodies 3, the central side surface of the coil body 3, and the lower side surface of the coil body 3.

<Measurement / test results>
FIG. 6 shows the results of the tank side impact test and the actual operation vibration measurement results obtained by fast Fourier transform (FFT) at 500 Hz or less. In FIG. 6, the upper four lines show the impact test results. In FIG. 6, one lower line is the actual operation vibration measurement result, and only the result of the sensor position 3C is shown as an example.
The four data of the impact test results shown in FIG. 6 have peaks at substantially the same frequency position, and these peak frequencies represent the natural frequencies of the upper peripheral wall 31a.
In the display of the vibration mode such as (2, 1) shown on the upper side in the graph of FIG. 6, the number on the left in parentheses indicates the number of antinodes in the longitudinal direction of the side plate, and the numerical value on the right indicates the number of antinodes in the lateral direction. Represents a number. This display corresponds to the unique modes shown in Tables 1 and 2 described in Takaoka Review, Vol.56 No. 1 (2011), "Vibration Analysis of Transformer Tanks" by Atsushi Katayanagi.

From the results shown in FIG. 6, it was confirmed that the upper peripheral wall 31a is self-excited as if it resonates at the power supply system frequency. The numbers shown in the lower part of FIG. 6 are the vibration modes of the power supply system, which are incomplete as the vibration modes, so add a dash outside the parentheses such as (1,1) and add a dash like (1,1)'. displayed. In addition to the vibration mode represented by an integer, vibrations with different numbers of antinodes in the longitudinal direction were also observed, and were expressed with indexes such as (1.5, 2) and (2.5, 2).
From these results, it goes without saying that the actual operating peak of the upper peripheral wall 31a includes the side natural frequencies such as (2,1) mode and (1.5,2) mode in addition to the power system vibration component. It was found that the vibration component other than the vibration component of the power supply system was also contained in.

<Measurement of the side of the tank when the operation is stopped>
FIG. 7 shows a waterfall diagram of the measurement results when the side of the tank is stopped. In the waterfall diagram, the horizontal axis frequency is 0 to 1000 Hz, the vertical axis time (right horizontal axis) is 0 to 120 seconds, and the left color scale bar shows the signal strength (m / s ² ). The signal strength is displayed logarithmically on the color scale bar, with the lower 4.5 / 10 range being ^{the level (x10-6} ) and the central 4.5 / 10 range being (x10 ^-3 ). Level, the upper 1/10 range indicates the level of 1 to 1.
In FIG. 7, the frequency scale on the horizontal axis means in increments of 200 Hz, representing 0, 200, 400, 600, 800, 1000 Hz, and one scale on the right vertical axis represents 20 seconds, 20, 40, 60, It represents 80, 100, 120 seconds.
Transformer 1 was stopped approximately 25 seconds after the start of measurement. The lower graph of the waterfall diagram shows the signal spectrum at 20 seconds.
Marked with ▲ mark the position of the acceleration 500 meters / ^{s 2} on the vertical axis in FIG. 7, but an acceleration of up to a position near the position 50 m / ^{s 2} acceleration 300 meters / ^{s 2} on the vertical axis is shown in gray in FIG. 7 The spectrum is shown.
In FIG. 7, the other spectra were regions in which the spectra shown in gray were slightly mixed in the black regions showing accelerations in the vicinity of 20u to 200u in the acceleration on the vertical axis. Incidentally, waterfall diagram in FIG. 7 is actually a color scale, the acceleration of the position of 200 m / ^{s 2} in the vertical axis 50 m / ^{s 2} is the acceleration 300 meters / ^{s 2} in the vertical axis of the position 50 m / ^{s 2} the acceleration of the position to the vicinity of a different color, but the spectrum corresponding to the acceleration of the position of 200 m / s ² of 50 m / s ² on the vertical axis in FIG. 7 is not displayed.

As shown in FIG. 7, it can be seen that the vibration of the power supply system which is an integral multiple and a half-integer multiple of 60 Hz almost disappears at the timing when the transformer is stopped. That is, with the passage of time (t) shown on the right vertical axis of FIG. 7, various vibrations shown in black at various frequencies disappear in the middle, resulting in a light gray graph of color. , Indicates that the signal has disappeared except in the low frequency band. Vibrations that are non-integer multiples of 60 Hz and disappear when the transformer is stopped are considered to be mechanical vibration peaks.
On the other hand, in the low frequency band of about 150 Hz or less, vibration remains even if the transformer 1 is stopped. The peak that does not disappear even when the transformer 1 is stopped in this way is presumed to be a vibration component derived from the building or other operating equipment.

<Ambient noise measurement>
The measurement result (base XYZ) of the sensor 22 installed on the transformer stand (concrete stand) of the building where the transformer 1 is installed while the transformer 1 is operating at a load factor of about 10% and the transformer 1 are installed on the floor of a separate room of the building. The measurement result of the sensor (separate room XYZ) is shown in FIG.
As shown in FIG. 8, large peak noise of an integral multiple of 60 Hz is observed in a wide frequency region. At 250 Hz and above, there is ^{continuous vibration of about 10-5} m / s ^2, and the vibration is slightly smaller on the floor of the separate room than on the transformer stand. At 250 Hz or less, a relatively large vibration of about ^{10 -4} m / s ² was observed in both the transformer stand and the floor of the separate room.

Next, with respect to the sensor 22 installed on the wall surface of the building facing the side wall of the transformer, the measurement results during the transformer operation (no load) and the measurement results after the transformer is stopped are shown in FIG.
^{As shown in FIG. 9, vibration of about 10 -4} m / s ² is observed on the high frequency side (250 Hz or higher), the acceleration is reduced by about half when the transformer 1 is stopped, and peak noise that is an integral multiple of 60 Hz is generated. Had disappeared. However, the vibration below about 250 Hz does not change even when the transformer is stopped.
A waterfall diagram of wall vibration is shown in FIG. In FIG. 10, the horizontal axis frequency indicates 0 to 1000 Hz and the vertical axis time indicates 0 to 120 seconds, and the scale bar in the left color indicates the signal strength, which is different from the scale setting in FIG. Signal strength, color scale are logarithmic display in bar, the lower levels in the range of 1/3 100~900u (× ^{10 -6),} the range of the central one-third is 1 to 10 m (× 10 ^{- The level of 3} ) and the upper 1/3 range indicate the level of 10 to 90 m (× 10 ^-3).
The lower graph in FIG. 10 shows the signal spectrum at 20 seconds.
In addition, FIG. 10 is a graph actually displayed on a color scale, and the acceleration on the vertical axis is purple for 100u to 200u, blue for 300u to 900u, which gradually becomes lighter from dark blue, green for 2m to 9m, and around 20m. Yellow and 30 m or more are shown on a color scale that gradually becomes dark red.
Although the color cannot be displayed in FIG. 10, the frequency higher than 800 Hz on the horizontal axis (right side) is generally a region with a lot of purple, the range of 600 to 800 Hz is a mixed region of purple and dark blue, and the frequency of 400 to 600 Hz is dark blue to light blue. Is a region where green is mixed with light blue at 400 Hz or less, and this green region is a region where acceleration of 2 m to 9 m is measured. In FIG. 10, this green area is displayed in gray for black-and-white display. Therefore, in the region of 0 to 200 Hz, the acceleration of approximately 2 m to 9 m is displayed, the region displayed brightly in the meantime indicates the region in which the acceleration of 20 m or more is measured, and the region displayed darkly indicates the region of 30 m or more.

As shown in FIG. 10, peak noise that is an integral multiple of 60 Hz (acceleration displayed as a gray spectrum at 200 to 1000 Hz displayed in FIG. 7) disappears at the timing of transformer stop, whereas it is approximately 250 Hz. It can be seen that the following noise remains unchanged even after the transformer is stopped.
The former is an electromagnetic noise signal induced in the sensor 22, which is different from the actual vibration, and it is considered that the cause is that the transformer 1 is excited. When diagnosing a transformer by measuring the vibration intensity of the power supply system frequency component, it may be affected by the electromagnetic noise generated from the transformer 1 in operation, and it is necessary to use a sensor with measures against electromagnetic noise. It is believed that there is.
The latter is considered to be a vibration noise signal caused by the actual shaking of the entire building. The effect will be described later.

"Impact test at the time of dismantling"
<Sensor top plate, dot top plate measurement>
The sensor 22 was installed on the top plate, the hitting point with the impact hammer was set on the top plate 31A, the transformer 1 was disassembled after stopping, the contents of the transformer were suspended from the top plate, and the top plate and the contents of the transformer were impact tested. The vibration analysis result (FFT result) of the case is shown in FIG.
When the top plate 31A was hammered with an impact hammer, a complicated spectrum was obtained as shown in FIG. For comparison, the FFT results when the side wall is impact-tested after the transformer 1 is stopped are set to linear on the vertical axis and 2000 Hz on the horizontal axis (aligned with FIG. 11) and shown in FIG.
As shown in FIG. 12, the FFT result when the side wall was impact-tested had a small number of peaks, a sharp peak shape in which the peaks did not overlap each other, and a simple spectrum as a whole.
On the other hand, in the FFT result shown in FIG. 11, the top plate 31A is connected to the upper yoke holding metal fitting 10, the coil holding plate 7, and the axial tightening bolt 8 through the hanging metal fitting 12, and the upper yoke holding metal fitting 10 is axially connected. It is connected to the lower yoke holding metal fitting 10 through the tightening bolt 8, and the iron core 5 and the winding 4 are fixed by them. Therefore, the top plate 31A is coupled to the iron core 5 and the winding 4, and has the natural vibration of each of the top plate 31A, the iron core 5, and the winding 4, and the natural vibration as a structure in which they are integrated. It is thought that there is.

<Sensor top plate, dot iron core measurement>
Vibration analysis result (FFT) when the sensor 22 is installed on the top plate 31A, the hitting point by the impact hammer is set to the iron core 5, the transformer 1 is stopped and then disassembled, the contents of the transformer are lifted, and the iron core 5 is impact tested. The result) is shown in FIG.
Since the large peak near 1060 Hz in FIG. 13 is seen to be large when the iron core 5 is hammered with an impact hammer, it is considered that the peak is derived from the natural vibration of the iron core 5.

<Sensor top plate, dot winding>
Vibration analysis result when the sensor 22 is installed on the top plate 31A, the hitting point by the impact hammer is set to the winding 4, the transformer 1 is stopped and then disassembled, the contents of the transformer are lifted, and the winding 4 is impact tested. (FFT result) is shown in FIG.
When the winding 4 was hammered with an impact hammer, sharp peaks were observed at 440 Hz and 1630 Hz as shown in FIG.

<Sensor winding, dot winding>
The top plate 31A and the tightening tool (axial tightening bolt 8) are removed, and the three coil bodies 3 and the coil holding plate 7 are raised in an integrated state, the sensor 22 is installed on the winding 4, and the winding FIG. 15 shows an example of the impact test result when No. 4 is hammered.
It is considered that the peak derived from the natural frequency of the winding 4 forms a wide peak as shown in FIG. In the winding 4 of the coil body 3 from which the top plate 31A and the axial tightening bolt 8 (tightening tool) are removed, the coil body 3 of each phase of UVW can vibrate substantially independently. This is because the coil holding plate 7 is divided for each coil body 3. As can be read from FIG. 15, the natural vibration of the winding 4 was found to have about 6 peaks between 0 and 2000 Hz.

From these test results, when the top plate 31A of the tank 31 is hammered with an impact hammer, vibrations are transmitted to the iron core 5 and winding 4 of the coil body 3 through the hanging metal fitting 12, and these vibrations are reflected and the top plate is reflected again. It is thought that it will be transmitted to 31A. Looking at the graph of FIG. 11 from such a viewpoint, it can be divided into a wide range of six peak groups in FIG. 11, a 1060 Hz peak derived from the iron core 5, a sharp 440 Hz and 1630 Hz peaks derived from the winding 4, and so on. It is considered that this suggests that the natural vibration of the contents of the transformer appears on the top plate 31A when the top plate 31A is hammered by the impact hammer.

Therefore, if an impact test is performed in which the top plate 31A is hit with an impact hammer, it can be considered that there is a possibility that the state of the contents of the transformer can be diagnosed by the vibration analysis.
On the other hand, the natural vibration as a structure in which the top plate 31A, the iron core 5, and the winding 4 are integrated is considered to appear in a low frequency region because the size and mass of the combined structural material are large. .. Therefore, the actual operating vibration measurement results shown in FIG. 6 and the dismantling impact test results in the range of 0 to 120 Hz are expanded and shown in FIGS. 16 to 19.

FIG. 16 is a diagram obtained by simply averaging the data obtained by FFT-converting the actual operation measurements at 32 locations on the side surface of the tank 31 for each frequency in the range of 0 to 120 Hz.
In the case of vibration measurement, if the sensor 22 is installed at a position corresponding to the vibration node, the amplitude becomes 0 with respect to the vibration mode, and the measurement is performed as if the sensor is not vibrating. Therefore, it is preferable to select as many installation positions as possible so that the sensor 22 is installed at a position other than the node in any vibration mode. Alternatively, it is preferable to perform multipoint measurement using a large number of sensors 22.
17, 18 and 19, respectively, are views showing the analysis results in detail by enlarging the horizontal axis frequencies of FIGS. 11, 13 and 14, respectively. Peaks near 22-28Hz, 52-58Hz, and 88Hz, which are seen when the contents of the transformer are hammered with an impact hammer, are also seen in the vibration peaks that occur on the top plate 31A when the top plate 31A is hammered, and have the same frequency. A peak appears in the actual operation vibration in the band.
As shown in these figures, the peak of the relatively low frequency that appears no matter where the top plate 31A, the iron core 5, and the winding are hammered is a structure in which the top plate 31A, the iron core 5, and the winding 4 are integrated. It is considered to be a vibration mode of the body, and it is considered that the vibration vibrates the side surface of the tank of the transformer 1 via the vibration of the top plate 31A or through the insulating oil in the transformer 1.

In the transformer 1, it was assumed that the electromagnetic mechanical force acting on the iron core 5 and the winding 4 was the excitation source of the natural vibration of the contents of the transformer. It is considered possible that the natural vibration of the transformer contents generated by the vibration shaking the transformer contents is captured by the upper peripheral wall surface of the tank.
The mass and arrangement of the members constituting the structure in which the top plate 31A, the iron core 5, and the winding 4 are integrated, and the tightening force for connecting them are also factors that determine the natural frequency. The spacer press board used for winding 4 deteriorates and causes volume shrinkage due to permanent strain, and the coupling becomes loose due to the effects of electromagnetic force and earthquakes caused by internal vibrations repeated for many years and sudden surge currents. It is considered that the natural frequency changes when it occurs.
Therefore, regarding the vibration of the contents of the transformer induced by the shaking of the building where the transformer 1 is installed, the abnormality or deterioration of the contents is diagnosed by monitoring the natural frequency with the vibration sensor 22 installed on the wall surface of the tank 1. I found that I could do it.

That is, when the building in which the transformer 1 is installed is vibrating, it is considered that the vibration of the building causes the transformer 1 to vibrate, which induces the vibration of the contents of the transformer and the vibration is transmitted to the tank wall surface. .. Therefore, it was found that the transformer 1 can be diagnosed by the vibration analysis by the sensor 22 using the vibration of the building.
The building of the transformer 1 measured this time has a large vibration of 250 Hz or less, and in the frequency region, the natural vibration of the structure in which the top plate 31A, the iron core 5 and the winding 4 are combined as an integral body can be captured on the side surface of the tank. It is thought that it was.
Therefore, in order to perform an abnormality diagnosis of the transformer 1 in operation using the vibration of the building, a transformer in an initial state that seems to be sound is operated, and the transformer has a large vibration component of 250 Hz or less from the building. Is transmitted, the vibration generated in the transformer 1 in a sound state is measured and grasped, and the FFT result obtained by fast Fourier analysis of this vibration information is stored in the memory of the signal analyzer 26 of the diagnostic device A or the like. deep.

As an example, the analyzer 26 and the arithmetic unit 27 shown in FIG. 1 are composed of a personal computer, the arithmetic unit 27 is a CPU, and a storage device such as a memory or a hard disk is mounted on the analyzer 26. The storage device of the above stores the FFT result of high-speed Fourier analysis of the vibration information of the transformer in a sound initial state. Also, record the frequency of the natural frequency appearing in the vibration information and the magnitude of its peak.
On the other hand, environmental vibration (environmental noise) from the building is added, and in order to diagnose the transformer in the operating state to be measured, the measurement target is under the same conditions as the actual operating vibration measurement explained above. Vibration is measured on the peripheral wall of the transformer.

The above condition is that the actual operating vibration of the right wall surface of the upper peripheral wall 31a is measured with respect to the transformer 31 operating at a load factor of about 10%, and an odd number of rows (1,3,5,7,9,11,13) is measured. , 15), a total of 8 × 4 = 32 points in rows A, C, E, and G were used, and the sensors were moved in sequence to measure each point for 10 seconds, which was obtained by this measurement. This is the analysis information of the result of fast Fourier transform of the obtained result.
The arithmetic unit 27 compares and examines the previous analysis information stored in the analyzer 26 and the analysis information obtained from the transformer to be measured, and examines the mechanical natural frequency and its natural frequency found in the transformer in the initial state. When a change in amplitude occurs or the presence of a new natural frequency peak that is not seen in the initial state is detected, it is determined that the transformer to be measured has some abnormality, and abnormality detection is determined. .. If necessary, this abnormality detection is displayed on the display device connected to the arithmetic unit 27.
If the inspector verifies the peak of the intrinsic frequency displayed on the display device and detects the peak of the intrinsic frequency that did not occur in the sound transformer in the initial state, for example, the magnitude of the new detection peak and the new detection The life of the transformer to be measured can be diagnosed according to the size and frequency of the number.
If even one new frequency component appears compared to the initial state, it can be determined that there is a high possibility that an abnormality has occurred in the transformer to be measured.

As another example, the storage device of the analyzer 26 shown in FIG. 1 stores the FFT result obtained by fast Fourier analysis of the vibration information of the impact test of the transformer in a sound initial state.
On the other hand, in order to diagnose the transformer in the operating state to be measured, an impact test is performed on the transformer to be measured under the same conditions as the impact test described above, and a part of the peripheral wall of the transformer is subjected to the impact test. Vibration is measured on the peripheral wall of the transformer to be measured under the same conditions as the actual operation vibration measurement described above.

The above condition is to perform an impact test on the right wall surface of the upper peripheral wall 31a with respect to the transformer 31 operating at a load factor of about 10%, and two sensors are used at positions 3C and 13F shown in FIG. The condition is that the hammer is installed and the hammer is hit at two points, position 4C and position 13E. Of course, the result of performing the same test as many times as necessary for the other positions shown in FIG. 4 may be used.
The analysis information of the result of the high-speed Fourier transform of the measurement result obtained under the above conditions is stored in the memory of the analyzer 26 or the like.
The arithmetic unit 27 compares and examines the previous analysis information stored in the analyzer 26 and the analysis information obtained from the transformer to be measured, and determines the existence of a natural frequency peak that is not found in the transformer in the initial state. When it is detected, it is determined that the transformer to be measured has some abnormality, and the abnormality detection is determined. If necessary, this abnormality detection is displayed on the display device connected to the arithmetic unit 27.
If the inspector verifies the peak of the intrinsic frequency displayed on the display device and detects the peak of the intrinsic frequency that did not occur in the sound transformer in the initial state, for example, the magnitude of the new detection peak and the new detection The life of the transformer to be measured can be diagnosed according to the size and frequency of the number.
Regarding the judgment criteria when diagnosing transformers, it is possible to accumulate the measurement results using multiple transformers and determine some judgment criteria based on the measurement results of multiple transformers. An accurate diagnosis can be made. More accurate diagnosis can be made by setting the judgment criteria for each transformer in consideration of the scale and durability of the transformer.

A ... Diagnostic device, 1 ... Transformer, 2 ... Tank, 3 ... Coil body, 5 ... Iron core, 6 ... Yoke, 7 ... Coil holding plate, 8 ... Axial tightening bolt, 10 ... Upper yoke holding metal fitting, 11 ... Upper yoke holding bolt, 12 ... hanging bracket, 22 ... vibration detector (accelerometer), 23 ... voltmeter, 24, 25 ... amplifier, 26 ... analyzer, 27 ... arithmetic unit, 31 ... tank, 31A ... top plate, 31a ... upper peripheral wall, 31B ... peripheral wall, 31b ... middle peripheral wall, 31c ... bottom peripheral wall, 31D ... bottom wall.

Claims (12)

It is a method for diagnosing internal abnormalities and deterioration of a transformer equipped with windings and iron cores constituting a coil body and a tank for accommodating them.
The tank is a box body composed of a bottom wall, a peripheral wall, and a top plate, and the coil body is formed by winding a winding around an iron core extending in the vertical direction, and the coil bodies are arranged vertically. With respect to the transformer having a configuration in which the coil body is tightened from above and below by the coil holding plate, and the tightened coil body is suspended from the top plate by a hanging metal fitting and housed inside the tank.
Wherein while by energizing the windings running the transformer, a mechanical vibration obtained by tapping the top plate with a hammer in the tank with no striking force hinder the transformer is operating the tank Based on the mechanical vibration generated at each position of the vibration detector in the tank using the vibration detectors installed at a plurality of locations, the vibration peak is an integral multiple of the power supply frequency, which is the characteristic peak during the operation of the transformer. Observe a plurality of vibration peaks that are different from the above and are caused by the difference between the natural frequency at each vibration detector installation position and the natural frequency inside the transformer.
From these plurality of vibration peaks, the vibration peak derived from the iron core, the vibration peak derived from the winding, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated are distinguished. The transformer internal abnormality and the transformer internal abnormality characterized in that the state of the transformer is analyzed by recognizing and observing the change of the vibration peak derived from the structure in which the top plate, the iron core and the winding are integrated. Deterioration diagnosis method. The top plate and the core determined as the winding respect vibration peak derived from structures that integrate in claim 1, wherein said top plate in the transformer healthy initial core and the winding To integrally The method for diagnosing an abnormality and deterioration inside a transformer according to claim 1, wherein the state of the transformer in operation is analyzed in comparison with the vibration peak derived from the structure. An area is divided into a part of the peripheral wall of the tank of the transformer to be measured in the actual operating state, acceleration sensors are installed at a plurality of positions in the section, and the top plate is hit with a hammer from the peripheral wall of the tank. The obtained vibration is measured as the output waveform of the accelerometer at each of multiple positions, and these output waveforms are subjected to high-speed Fourier conversion to plot the frequency on the horizontal axis and the amplitude on the vertical axis. The internal abnormality of the transformer according to claim 2, wherein the peak is analyzed and the state of the operating transformer is analyzed by comparing with the peak of the natural frequency obtained by the equivalent method for the sound transformer. And how to diagnose deterioration. A winding body constituting a coil body, an iron core, and a tank for accommodating these are provided, and the tank is a box body composed of a bottom wall, a peripheral wall, and a top plate, and is wound around the iron core extending in the vertical direction. The coil body is formed by winding the coil body, the coil body is tightened from above and below by a coil holding plate arranged vertically, and the tightened coil body is suspended from the top plate by a hanging metal fitting to the tank. a diagnosis apparatus for an internal fault and the deterioration of the transformer inside the stowed configuration of,
A plurality of vibration detectors mounted on a plurality of locations in the tank with respect to an operating transformer and having detection sensitivity to vibrations from a low frequency region to an audible sound region (1 Hz to 20 kHz) generated by the transformer.
Installation of the vibration detector of the tank obtained by hitting the top plate of the tank with a hammer with a striking force that does not interfere with the operation of the transformer while the winding is energized and the transformer is operating. Based on the mechanical vibration generated at each position, the vibration peak is different from the vibration peak that is an integral multiple of the power supply frequency, which is the characteristic peak during transformer operation, and is the natural frequency at each position where the vibration detector is installed. An analyzer that observes a plurality of vibration peaks caused by different natural frequencies inside the transformer, and
From these plurality of vibration peaks, the vibration peak derived from the iron core, the vibration peak derived from the winding, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated are distinguished. It is characterized by having a calculation means for analyzing the state of the transformer by recognizing and observing the change of the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated. Diagnostic device for internal abnormalities and deterioration of transformers. Information on the natural frequency of a sound transformer is recorded in the calculation means, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated and the soundness are detected by the vibration detector. The inside of the transformer according to claim 4, wherein the calculation means has an ability to compare vibration peaks derived from a structure in which the top plate, the iron core, and the winding of the transformer are integrated. Diagnostic device for abnormalities and deterioration. The information on the natural frequency of the sound transformer recorded in the calculation means is obtained by partitioning an area into a part of the peripheral wall of the tank in the operating state of the sound transformer and accelerometers at a plurality of positions in the section. Is installed, the top plate is hit with a hammer, the vibration obtained from the peripheral wall of the tank is measured as the output waveform of the accelerometer at each of a plurality of positions, and these output waveforms are subjected to high-speed Fourier conversion and the horizontal axis is the frequency. It is the analysis result of the peak of the natural frequency that appears in the waveform obtained by plotting the amplitude on the vertical axis, and the information of the natural frequency of the transformer to be measured compared with this information is the operating state of the measurement target by the same method. The diagnostic device for internal abnormality and deterioration of a transformer according to claim 5, which is an analysis result of a peak of a natural frequency obtained from the transformer of the above. It is a method for diagnosing internal abnormalities and deterioration of a transformer equipped with windings and iron cores constituting a coil body and a tank for accommodating them.
The tank is a box body composed of a bottom wall, a peripheral wall, and a top plate, and a coil body is formed by winding a winding around an iron core extending in the vertical direction, and the coil body is arranged vertically. With respect to the transformer having a configuration in which the coil body is tightened from above and below by a coil holding plate, and the tightened coil body is suspended from the top plate by a hanging metal fitting and housed inside the tank.
The building in which the transformer is installed is a building that vibrates in response to vibration from other equipment installed in the building or vibration caused by environmental noise in the vicinity of the building, and the vibration from this building is transmitted to the transformer. The vibration in the case of the above is detected by the vibration detector installed on the peripheral wall surface of the tank, and the vibration is detected.
The vibration peak is different from the vibration peak that is an integral multiple of the power supply frequency, which is the characteristic peak during operation of the transformer, and the natural frequency at each vibration detector installation position and the natural frequency inside the transformer are different. Observe the multiple vibration peaks caused by this and
From these plurality of vibration peaks, the vibration peak derived from the iron core, the vibration peak derived from the winding, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated are distinguished. The transformer internal abnormality and the transformer internal abnormality characterized in that the state of the transformer is analyzed by recognizing and observing the change of the vibration peak derived from the structure in which the top plate, the iron core and the winding are integrated. Deterioration diagnosis method. Relates vibrational peak of the top plate and the core and the winding-derived structure is integral obtained in claim 7, wherein the winding and the top plate and the core in the transformer healthy initial state To integrally The method for diagnosing an abnormality and deterioration inside a transformer according to claim 7, wherein the state of the transformer in operation is analyzed in comparison with the vibration peak derived from the structure. An area is divided into a part of the peripheral wall of the tank of the transformer to be measured in the actual operating state, acceleration sensors are installed at a plurality of positions in the section, and the frequency is obtained from the peripheral wall of the tank based on the vibration of the building. The generated vibration is measured as the output waveform of the acceleration sensor for each of multiple positions, and these output waveforms are subjected to high-speed Fourier conversion, and the peak of the natural frequency that appears in the waveform obtained by plotting the frequency on the horizontal axis and the amplitude on the vertical axis. The internal abnormality of the transformer and the internal abnormality of the transformer according to claim 8, wherein the state of the operating transformer is analyzed by comparing with the peak of the natural frequency obtained by the equivalent method for the sound transformer. Deterioration diagnostic method. A winding body constituting a coil body, an iron core, and a tank for accommodating these are provided, and the tank is a box body composed of a bottom wall, a peripheral wall, and a top plate, and is wound around the iron core extending in the vertical direction. The coil body is formed by winding the coil body, the coil body is tightened from above and below by a coil holding plate arranged vertically, and the tightened coil body is suspended from the top plate by a hanging metal fitting to the tank. a diagnosis apparatus for an internal fault and the deterioration of the transformer inside the stowed configuration of,
It has detection sensitivity for vibrations from the low frequency region to the audible sound region (1 Hz to 20 kHz) generated by the transformer, which is installed in a plurality of locations in the tank and is installed and operated in the building. Vibration detector and
Upon receiving the detection signal from the vibration detector, the mechanical vibration based on the phase of the transformer vibration including the vibration transmitted from the building to the operating transformer is obtained and analyzed.
Based on the mechanical vibration generated at each position of the vibration detector in the tank, the vibration peak is different from the vibration peak that is an integral multiple of the power supply frequency, which is the characteristic peak during operation of the transformer, and is different from the vibration peak. An analyzer that observes multiple vibration peaks caused by the difference between the natural frequency at each installation position and the natural frequency inside the transformer, and
From these plurality of vibration peaks, the vibration peak derived from the iron core, the vibration peak derived from the winding, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated are distinguished. It is characterized by having a calculation means for analyzing the state of the transformer by recognizing and observing the change of the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated. Diagnostic device for internal abnormalities and deterioration of transformers. Information on the natural frequency of a sound transformer is recorded in the calculation means, and the vibration peak derived from the structure in which the top plate, the iron core, and the winding are integrated and the soundness are detected by the vibration detector. The inside of the transformer according to claim 10, wherein the calculation means has an ability to compare vibration peaks derived from a structure in which the top plate, the iron core, and the winding of the transformer are integrated. Diagnostic device for abnormalities and deterioration. The information on the natural frequency of the sound transformer recorded in the calculation means is obtained by partitioning an area into a part of the peripheral wall of the tank in the operating state of the sound transformer and accelerometers at a plurality of positions in the section. Is installed, and the vibration obtained from the peripheral wall of the tank is measured as the output waveform of the accelerometer at each of a plurality of positions based on the vibration of the building. It is the analysis result of the peak of the natural frequency appearing in the waveform obtained by plotting the amplitude in, and the information of the natural frequency of the transformer to be measured compared with this information is the transformation of the operating state of the measurement target by the same method. The diagnostic device for internal abnormality and deterioration of a transformer according to claim 11, which is an analysis result of a peak of a natural frequency obtained from the device.

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