KR100928534B1 - Transformer Deterioration Diagnosis Apparatus and Method Using Fiber Optic Sensor - Google Patents

Abstract

In the device of the present invention for diagnosing the degree of degradation of a transformer using an optical fiber sensor, the ultrasonic wave generated by partial discharge is separated and analyzed for each frequency band, and then stored and stored from the database and the laser (1). A coupler 2 for separating the generated laser beam into two beams, and a part of the beam separated from the coupler 2 passes through the reference coil 3, and part of the sensing is mounted inside the transformer 10. An optical fiber passing through the coil 4, a coupler 5 for transmitting the light beams passing through each optical fiber together, an optical detector 6 for measuring the intensity of the light beams passing through the coupler 5, and the optical sword An A / D converter 7 for converting the analog signal measured by the digitizer 6 into a digital signal, an oscilloscope 8 displayed on the screen after converting the digitized signal into an ultrasonic signal, It is characterized in that it comprises a signal processor (9) for diagnosing whether the band of the ultrasonic signal belongs to the frequency band well generated partial discharge, and diagnoses the degradation state of the transformer according to the result.

partial discharge, ultrasonics, high-voltage transformer, wavelet transform, insulation diagnosis

Description

Diagnosis apparatus and method of degradation of a transformer using optical fiber sensor

1 is a schematic diagram of a transformer degradation diagnostic apparatus using an optical fiber sensor according to an embodiment of the present invention.

2 is a view for explaining the principle of ultrasonic analysis by frequency domain of the transformer degradation diagnostic apparatus of the present invention.

3 is a graph showing the transformer degradation diagnosis results measured by the transformer degradation diagnosis apparatus of the present invention, and is a frequency spectrum distribution diagram when partial discharge occurs.

4A and 4B are graphs of frequency component analysis in the time domain based on FIG. 2, respectively, through a software bandpass filter.

<Description of Symbols for Major Parts of Drawings>

1: laser

2, 5: coupler

3: Reference coil

4: sensing coil

6: photodetector

7: A / D converter                 

8: oscilloscope

9: signal processor

10: transformer

The present invention relates to a transformer degradation diagnosis apparatus and method using an optical fiber sensor capable of diagnosing a degradation state of a transformer by an on-line, non-contact method.

In general, the maintenance and repair of power equipment and equipment is important for the efficient supply of stable and reliable power, and in order to prevent accidents, the signs of accidents can be detected in advance to prevent the expansion of large accidents. There is a need for always-on monitoring diagnostics.

In this point of view, the breakdown of the transformer appears as the main cause of the accident. By detecting the partial discharge occurring immediately before the breakdown, the accident can be prevented. Phenomenon that occurs during partial discharge includes discharge pulse current generation, ultrasonic waves, vibration, radiated electromagnetic field, light, insulator decomposition and gas generation, increased power loss, partial dielectric breakdown, and the like.

As a conventional measuring method for detecting such a phenomenon, a chemical, mechanical, optical, or electrical method is used.

Among them, the chemical method is to confirm the state in which the insulating material is decomposed and deteriorated by partial discharge by chemical method, to measure the acid value of the insulating oil and to analyze the generated gas.

In addition, the mechanical method is to detect the minute vibration generated during partial discharge, the vibration acceleration method is a typical method, the ultrasonic detection method is one kind.

The optical method detects light generated during partial discharge, also referred to as luminescence detection.

Finally, various methods are used again for the electrical method, such as the coupling capacitor method for measuring the discharge pulse current, the ground line current detection method, and the dielectric loss tangent method for measuring the power loss increase.

By the way, this method is mostly commercially available, but there are many difficulties in constructing a system capable of constantly monitoring the deterioration of the transformer.

On the other hand, representative examples for bringing such a monitoring system online are an antenna method for measuring radiated electromagnetic waves generated during partial discharge, and a method for measuring ultrasonic waves by attaching a piezoelectric element type sensor to a device case.

The antenna method has a problem that a signal is distorted by ambient noise or electromagnetic coupling.

In addition, the piezoelectric ultrasonic sensor has an advantage of being easily installed in a desired area by using a magnetic fixing device without being affected by electrical noise, but the acoustic signal generated by the partial discharge reaches the ultrasonic sensor. Because it is attenuated by a medium, an insulating structure, or the like, a partial discharge signal from a distance from the sensor is extremely difficult to detect, and in addition to the signal transmitted directly from the discharge source and other media such as a metal wall, even when an acoustic signal is transmitted. In case of overlapping signals transmitted indirectly, there is a problem in that it is difficult to detect the magnitude or location of the discharge.

The present invention has been made to solve the above problems, by configuring a Mach-Gender interferometer using an optical fiber sensor to measure the minute change of the length between the signal wave and the reference wave to measure the ultrasonic wave generated during partial discharge, transformer The present invention aims to provide an apparatus and method for diagnosing transformer degradation using an optical fiber sensor capable of detecting and diagnosing the degradation state of the sensor in an on-line, non-contact manner early.

In order to achieve the above technical problem the device of the present invention

In the device for diagnosing the degree of degradation of the transformer using a fiber optic sensor,

A database configured by separating and analyzing the ultrasonic waves generated by the partial discharge for each frequency band, and storing the ultrasonic waves;

A coupler 2 for separating the laser beam generated from the laser 1 into two beams,

A part of the light beam separated from the coupler (2) passes through the reference coil (3), and a part of the optical fiber passing through the sensing coil (4) mounted inside the transformer 10,

Coupler (5) for transmitting together the light beams passing through each optical fiber,                     

An optical detector 6 for measuring the intensity of the light beams passing through the coupler 5,

An A / D converter 7 for converting the analog signal measured by the photodetector 6 into a digital signal;

An oscilloscope 8 displayed on the screen after converting the digitized signal into an ultrasonic signal;

And a signal processor 9 for analyzing whether the band of the ultrasonic signal belongs to a frequency band in which partial discharge of the database is easily generated, and diagnosing a deterioration state of the transformer according to the result.

On the other hand, the method of the present invention

In the method for diagnosing the degree of degradation of the transformer using an optical fiber sensor,

Separating and analyzing the ultrasonic waves generated by the partial discharges according to frequency bands, and then database them;

Separating the laser beam generated from the laser 1 into two beams using the coupler 2,

A part of the light beam separated from the coupler 2 passes through the reference coil 3 and a part passes through the sensing coil 4;

Transmitting the light rays passing through each of the reference coil 3 and the sensing coil 4 together using another coupler 5;

Measuring the intensity of the light beam,

Converting the measured analog signal into a digital signal;

Converting the digitized signal into an ultrasonic signal and outputting the converted ultrasonic signal;                     

And analyzing whether the band of the ultrasonic signal belongs to a frequency band in which partial discharge of the database is easily generated, and diagnosing a deterioration state of the transformer according to the result.

Hereinafter, the configuration and operation of the present invention as described above will be described in more detail with reference to the accompanying drawings.

1 is a schematic diagram according to one embodiment of the apparatus of the present invention.

As shown in this figure, the laser beam generated from the laser 1 has a coupler 2 attached to the front of the laser for coupling to a single mode optical fiber. The laser beam coupled to the single mode optical fiber passes through the coupler 2 and is then split into two beams.

Some of the light beams separated from the coupler 2 pass through the reference coil 3 which is not affected by the partial discharge, and some of the sensing coils 4 installed in the insulating oil of the transformer 10 may be partially discharged. As it passes, it is affected by ultrasound. The laser beams passing through these different paths are then combined into a single beam by the coupler 5.

The light beams passing through the coupler 5 are measured by the light detector 6 in the form of an analog signal, which is converted into a digital signal by the A / D converter 7 and then the oscilloscope 8 ) As an ultrasonic signal.

Thereafter, the signal processor 9 analyzes the ultrasonic waveform for each frequency region of the ultrasonic wave, and outputs a deteriorated state of the transformer.

Hereinafter, the principle of the diagnostic device and method of deterioration state of the transformer of the present invention configured as described above will be described.

As shown in FIG. 1, the paths through which the laser beam passes are all composed of optical fibers. The optical fiber sensor used in the present invention has many advantages as a sensor due to the advantages of low loss, small size, light weight, wide bandwidth, induction, strong corrosion resistance, especially high sensitivity, and the material is made of a dielectric to insulate the device. While providing flexibility in design, the measurement method is non-contact and has high accuracy, making it suitable for various applications.

This measurement technique using the optical fiber sensor, such as the present invention, by installing the sensor 4 inside the transformer 10, it is possible to precisely measure the external noise as possible. In addition, since the distance between the two paths is determined by the length of the optical fiber, no effort is required to match the path lengths.

In addition, since the optical fiber is used, the optical fiber may be added to the part requiring measurement, and thus the configuration of the sensor may be facilitated, and the area of the reference wave may be less affected by other external influences.

Finally, the optical fiber is made of a dielectric material (glass, plastic, etc.), which has the advantage that the electromagnetic field, such as a power device, can be located inside a complex device. In one embodiment of the present invention, the optical fiber sensor is wound on the mandrel for the purpose of increasing the sensitivity of the optical fiber sensor.

In this case, when the length of one optical fiber of the two light beams is changed, the intensity of the output light is determined by the phase difference φ generated by passing through two different paths. Thus, by measuring the intensity of this output light, a minute change in length is detected, and ultrasonic waves are detected through this.

In an embodiment of the present invention, an optical fiber sensor is configured for the purpose of insulating transformer insulation diagnosis.

In the case of a conventional piezoelectric element type ultrasonic sensor, it is used to attach to the case of the device, so that ultrasonic waves generated inside the device are measured through an insulator medium and through a metal enclosure. The weak signal is also weak. In order to identify this weak signal, an amplification element must be located after the sensor.

In contrast, in the case of transformer degradation diagnosis using ultrasonic measurement using optical fiber according to the present invention, since the optical fiber is made of a dielectric material, it can be placed inside the transformer, so that ultrasonic waves generated during discharge can be measured with high sensitivity. Resistant to noise

Here, the ultrasonic signal generated by the partial discharge is divided into analysis ranges through a software bandpass filter.

2 is a view for explaining the principle of ultrasonic analysis by frequency domain of the transformer degradation diagnostic apparatus of the present invention. This is illustrated for the segmentation step and the frequency range according to the frequency of the ultrasonic waves.

On the other hand, Figure 3 is a graph showing the transformer degradation diagnosis results measured by the transformer degradation diagnostic apparatus of the present invention, it is a frequency spectrum distribution chart when partial discharge occurs. Ultrasonic waves are generated over a wide range of frequencies 0 to 250 [MHz].

4A and 4B are graphs of frequency component analysis in the time domain based on FIG. 3, respectively, which have undergone a software bandpass filter.

Here, FIG. 4A shows a 125-250 [MHz] band signal separated from the circular signal, and shows no change compared to when there is no discharge signal. Therefore, it can be seen that the signal of this band cannot be used to determine whether the transformer 10 insulating oil is deteriorated.

On the other hand, Figure 4b shows a signal of the frequency 15.63 ~ 31.25 [MHz] band. This figure shows that the overall shape tends to decrease exponentially, and that the maximum magnitude is very large, indicating that partial discharge has occurred. Therefore, it can be seen that the insulating oil of the transformer 10 is deteriorated, and the larger the maximum value is, the more severe the deterioration degree is.

Therefore, the data such as the band and the maximum value are made into a database, and by referring to this database, the signal processor 9 can easily calculate and display the degree of deterioration by intensively examining only the band where the partial discharge occurs well. .

As such, a continuous monitoring system is required for insulation diagnosis, and in order to meet this demand, a frequency band having the largest change in discharge occurrence is selected, and an intensive analysis of this band is required, rather than data analysis of the entire frequency band region. This significantly reduces the time and effort of the analysis.                     

Although the technical idea of the apparatus and method for diagnosing deterioration of a transformer using the optical fiber sensor of the present invention has been described with the accompanying drawings, this is merely illustrative of the best embodiment of the present invention, which is intended to limit the present invention. It is not.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

According to the present invention as described above, by using a Mach-gender interferometer to measure the fine ultrasonic signal generated by the partial discharge, early detection of the degradation of the transformer to prevent large accidents, as long as the transformer reaches the end of its life It is effective to use for a long time. In addition, online diagnosis is easy by selecting a frequency band of ultrasonic waves by partial discharge and performing intensive analysis on the band.

Claims (2)

In the device for diagnosing the degree of degradation of the transformer using a fiber optic sensor, A database configured by separating and analyzing the ultrasonic waves generated by the partial discharge for each frequency band, and storing the ultrasonic waves; A coupler 2 for separating the laser beam generated from the laser 1 into two beams, A part of the light beam separated from the coupler (2) passes through the reference coil (3), and a part of the optical fiber passing through the sensing coil (4) mounted inside the transformer 10, Coupler (5) for transmitting together the light beams passing through each optical fiber, An optical detector 6 for measuring the intensity of the light beams passing through the coupler 5, An A / D converter 7 for converting the analog signal measured by the photodetector 6 into a digital signal; An oscilloscope 8 displayed on the screen after converting the digitized signal into an ultrasonic signal; And a signal processor (9) for analyzing whether the band of the ultrasonic signal belongs to a frequency band in which partial discharge of the database is easily generated, and diagnosing a deterioration state of the transformer according to the result. Transformer degradation diagnostic device used. In the method for diagnosing the degree of degradation of the transformer using an optical fiber sensor, Separating and analyzing the ultrasonic waves generated by the partial discharges according to frequency bands, and then database them; Separating the laser beam generated from the laser 1 into two beams using the coupler 2, A part of the light beam separated from the coupler 2 passes through the reference coil 3 and a part passes through the sensing coil 4; Transmitting the light rays passing through each of the reference coil 3 and the sensing coil 4 together using another coupler 5; Measuring the intensity of the light beam, Converting the measured analog signal into a digital signal; Converting the digitized signal into an ultrasonic signal and outputting the converted ultrasonic signal; Analyzing whether the band of the ultrasonic signal belongs to a frequency band in which partial discharge of the database is easily generated, and diagnosing the deterioration state of the transformer according to the result of the transformer degradation diagnosis using the optical fiber sensor Way.

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