KR20120066828A - Internal defect measuring device of transformer - Google Patents

Abstract

The present invention relates to a device for measuring internal defects of a transformer which detects an electrical signal and an acoustic signal accompanying an internal defect at the same time and accurately detects an internal defect and a location of the internal defect. A main sensor unit attached to an outer side of the housing, the main sensor unit analyzing a signal by measuring an acoustic signal accompanying partial discharge using a piezoelectric element and a sudden electric potential change occurring when partial discharge occurs, and attached to an outer side of the housing; And a plurality of sub sensor units for detecting and supplying an acoustic signal to the main sensor unit when the partial discharge occurs.

Description

Detecting internal cracks of transformer

The present invention relates to a transformer, and in particular, the internal defect measurement of the transformer to detect the electrical and acoustic signals accompanying the internal defect at the same time to accurately detect the internal defect and the location of the defect inside Relates to a device.

In general, with the increase in power demand, transformers are getting larger and ultra-high pressure, and substations are becoming unmanned. When an accident occurs in such a large-capacity transformer, its ripple effect is widespread, economic loss and psychological anxiety are enormous, and the need for insulation diagnosis to prevent the accident of the transformer is increasing.

Recently, in order to secure the reliability of the transformer and to supply the power stably, a constant monitoring device has been developed for measuring abnormal symptoms, which are the occurrence of an accident, in the operation state of the transformer at all times. Development of a preventive diagnostic system to stop the operation and take countermeasures when abnormal symptoms progress and determine the type of abnormality based on the correlation between the abnormal detection data and determine the type of abnormality. It is becoming.

In general, the transformer has a structure as shown in Figure 1 to transform the voltage to be used in power demand, such as factories and homes, for smooth power transmission and distribution. That is, FIG. 1 is a view showing the appearance and circuit of a general transformer.

As shown in FIG. 1, a transcoil consisting of a primary coil and a secondary coil and a magnetic field core for smooth mutual induction of the transcoil, and a housing accommodating the mutually defective transcoil and the magnetic field core are configured. do.

The housing is filled with an insulating insulating cooling oil (hereinafter referred to as 'insulating oil') to cool the heat generated in the transformation process, most of these insulating oils are petroleum-based, but some of them as non-combustible synthetic insulating oil, According to the present invention, the properties are various, and in general, they have high volumetric electrical resistance, low viscosity, and are stable to oxidation.

However, these transformers are frequently caused by thermal deterioration due to high temperature operation, thermal deterioration due to external short-circuit, mechanical damage and discharge deterioration due to partial discharge, resulting in mechanical breakdown, increased vibration, and flammable gas. Progress.

Therefore, the insulation breakdown of the transformer due to overheating has caused many problems such as explosion of the transformer and power failure.

In order to minimize the conventional failure of the transformer, on-line abnormality detection technology applied to the constant monitoring of the transformer includes a gas analysis technology, partial discharge measurement technology, temperature measurement technology and the like of the transformer insulating oil.

Here, partial discharge continuously degrades the insulation inside the transformer, resulting in a transformer insulation accident.

The internal defects in the transformers according to the prior art are measured using piezoelectric elements and acoustic signals using capacitive sensors when partial discharge occurs due to internal defects.

However, when the acoustic signal is detected by using a piezoelectric element to measure the internal defect of the transformer according to the prior art, the position estimation is difficult when the signal is detected only in one or two sensors among a large number of attached sensors. Very difficult.

In addition, when a piezoelectric element and a capacitive sensor are installed in a transformer to detect an acoustic signal and an electrical signal in a complex manner, when an internal defect occurs inside the transformer, the electrical signal is immediately detected by the light beam and the acoustic signal is weak in oil. 340 [m / s] can be used to help determine the exact location of the partial discharge because it can confirm the point of occurrence of partial discharge.However, when the piezoelectric element, the capacitive sensor, and the detection device are separately installed, the cost increases. Not suitable for low cost transformers.

The present invention is to solve the above problems and to detect the electrical and acoustic signals accompanying the internal defects at the same time at the same time to detect the internal defects and the location of the internal defects of the transformer accurately Its purpose is to provide an internal defect measuring apparatus.

An apparatus for measuring internal defects of a transformer according to the present invention for achieving the above object includes a housing constituting a transformer and an acoustic signal accompanying partial discharge using a piezoelectric element attached to an outer side of the housing and a sudden occurrence of partial discharge. And a plurality of sub sensor units attached to an outer side of the housing to detect a potential change and detect a sound signal when a partial discharge occurs and supply the acoustic signal to the main sensor unit. .

The internal defect measuring apparatus of the transformer according to the present invention has the following effects.

First, by attaching a piezoelectric element for measuring electrical signals and acoustic signals simultaneously on the outer surface of the transformer, it is possible to accurately detect the internal defect and the position of the defect by estimating the position of the partial discharge source when the partial discharge occurs inside the transformer.

Second, the piezoelectric element is formed by attaching electrodes to both sides of the dielectric, and an amplifier capable of amplifying an acoustic band signal when a partial discharge occurs due to an internal defect in a transformer, and an electrical signal having a sudden transient voltage type. By connecting the amplifiers in parallel, low-cost transformers can be installed by measuring electrical signals, including acoustic signals, in place of capacitive sensors.

Third, to set the point of time of the detected electrical signal as the origin of signal generation from the defect, calculate the time from the detection of the delayed signal to the delay time, calculate the distance from the sensor, and use only the normal acoustic signal as the location of the defect. The position can be analyzed more accurately.

Fourth, the acoustic signal is generally attenuated inside the transformer, so it is very difficult to estimate the position if only a small number of sensors attached to the sensor are detected. The location where this occurred can be estimated accurately.

1 is a view showing the appearance and circuit of a typical transformer
2 is a schematic view showing an internal defect measuring apparatus of a transformer according to the present invention
3 is a schematic view showing the inside of the internal defect measuring apparatus of FIG.
Figure 4 is a waveform diagram showing the waveform of the electrical and acoustic signals detected through the internal defect measuring device of the transformer according to the present invention

Hereinafter, an internal defect measuring apparatus of a transformer according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram showing the internal defect measuring apparatus of the transformer according to the present invention, Figure 3 is a schematic diagram showing the interior of the internal defect measuring apparatus of FIG.

As shown in FIGS. 2 and 3, the apparatus for measuring internal defects of a transformer according to the present invention includes a housing 110 constituting a transformer and an external piezoelectric element attached to an outer side of the housing 110 to prevent from a partial discharge. A main sensor unit 120 for analyzing a signal by measuring an accompanying acoustic signal and a sudden change in potential generated during partial discharge, and attached to an outer side of the housing 110 to detect an acoustic signal during partial discharge to detect the main sensor unit ( It is configured to include a plurality of sub-sensor unit 130 to supply to 120.

The main sensor unit 120 is attached to the housing 110 to detect a sound signal (AE) and an electrical signal (potential change) at the same time when a partial discharge occurs inside the transformer, and the piezoelectric element. An amplifier circuit 122 for amplifying the acoustic signal and the electrical signal detected by the element 121, and a frequency filter 123 for filtering the frequencies of the high frequency signals among the acoustic signal and the electrical signal amplified by the amplifier circuit 122, respectively. ), An A / D converter 124 for converting the acoustic signal and the electric signal filtered from the frequency filter 123 into digital signals, and an acoustic signal converted to the digital signal from the A / D converter 124, respectively. And a microprocessor 125 that receives the electrical signal, analyzes the factor of each signal, determines whether or not the actual partial discharge, and finally determines the position of the partial discharge, and a portion determined from the microprocessor 125. Communication module 126 for transmitting the position of the discharge to the outside, the display unit 127 for indicating the position of the partial discharge determined from the microprocessor 125, and the sound measured from the plurality of sub-sensor unit 130 And an A / D converter 128 for receiving a signal and converting the signal into a digital signal, and a power supply 129 for supplying power to each component.

Here, the power supply device 129 serves to supply power to the plurality of sub sensor units 130 as well.

The amplifying circuit for amplifying the sound signal of the amplifying circuit 122 amplifies and outputs the sound signal detected from the piezoelectric element 121 by 40 dB or more, and the frequency filter 123 is amplified from the amplifying circuit 122. Eliminate unused frequency band signals from sound signals. That is, the frequency filter 123 performs a function of filtering a signal of a frequency band that is out of a preset value (about 50 to 300 kHz) among frequency bands of the sound signal supplied from the amplifying circuit 122 at a predetermined ratio.

An amplifying circuit for amplifying an electric signal among the amplifying circuits 122 amplifies and outputs an electric signal detected from the piezoelectric element 121 by 10 dB or more, and the frequency filter 123 is amplified from the amplifying circuit 122. Eliminate unused frequency band signals from sound signals. That is, the frequency filter 123 performs a function of filtering a signal having a frequency band out of a preset value (about 1 to 300 MHz) among frequency bands of the electrical signal supplied from the amplifying circuit 122 at a predetermined ratio.

It is configured to include a monitoring device 140 for receiving a position from which the partial discharge from the main sensor unit 120 from the communication module 126 to monitor the transformer.

The piezoelectric element 121 of the main sensor unit 120 is used in the form of electrodes attached to both sides of the dielectric, which is an electrical signal in the form of a sudden transient voltage rather than an acoustic band when partial discharge occurs due to internal defects in the transformer. When connected in parallel with the amplification circuit 122 capable of amplifying, it is possible to measure not only an acoustic signal but also an electrical signal at the same time, so that it can be used as a substitute for a capacitive sensor.

In general, for electric signals, the frequency band of the filter is about 1 to 300 MHz, and for acoustic signals it is about 50 to 300 kHz.

The plurality of sub-sensor units 130 are attached to the housing 110 through a wear plate to detect a sound signal AE when a partial discharge occurs inside the transformer, and the piezoelectric element ( An amplifying circuit 132 for amplifying the sound signal detected from the 131 and a frequency filter 133 for filtering the frequencies of the ultra-high frequency signals among the sound signals amplified by the amplifying circuit 132, wherein the frequency filter ( The audio signal filtered from the 133 is transferred to the A / D converter 128 of the main sensor unit 120.

Figure 4 is a waveform diagram showing the waveform of the electrical signal and the acoustic signal detected by the internal defect measuring device of the transformer according to the present invention.

As shown in Fig. 4, in the case of detecting a signal in a complex manner, when an internal defect occurs inside the transformer, the electric signal is immediately detected by the sensor at the speed of light, but the acoustic signal is measured at the speed of about 340 [m / s] in water. Since there is a time delay compared to the transmitted electric signal, the distance from the sensor is calculated by setting the time point of the detected electric signal as the origin of signal generation from the defect and calculating the time until the acoustic signal is detected as the delay time. The position of can be analyzed much more accurately than the method using only general acoustic signal.

In addition, the acoustic signal is generally attenuated inside the transformer, so it is very difficult to estimate the position when only a small number of sensors attached to the sensor are detected. Can be detected more accurately.

The internal defect measuring apparatus of a transformer according to the present invention configured as described above includes a main sub unit 120 including a piezoelectric element 121 that simultaneously detects an acoustic signal and an electrical signal on an outer side of the transformer to a housing 110 of the transformer. And a plurality of sub sensor units 130 including piezoelectric elements 131 which detect sound signals in different numbers according to the size of the transformer while having a constant distance from the main sub unit 120. In the case of partial discharge, the electric signal propagated in all directions can be detected and the acoustic signal can be detected to accurately estimate the location of the partial discharge.

That is, the main sensor unit 120 uses the piezoelectric element 121 to measure the acoustic signal accompanying the partial discharge and the abrupt potential change generated when the partial discharge occurs, and the acoustic signal and the electrical signal detected by the piezoelectric element 121 are measured. The signal is amplified to facilitate the analysis through the amplifying circuit 122 and the frequency filter 123 is passed to remove signals in the frequency band not necessary for analysis.

Finally, the analog signal passed through the frequency filter 123 is converted into a digital signal through the A / D converter 124 and the signal is analyzed by the microprocessor 125. The microprocessor 125 analyzes the factors of the detected acoustic signals and the electrical signals, determines whether the actual partial discharge is performed, and finally determines the position of the partial discharge.

The result can be confirmed through the display unit 127 attached to the main sensor unit 120 and has a communication module 126 that can transmit the result to the remote monitoring device 140.

The number of the sub-sensor unit 130 is determined according to the size of the transformer, and is composed of two types like the main sensor unit 120 to measure only the acoustic signal in consideration of the economical efficiency and the sensor for measuring both the acoustic signal and the electrical signal. . According to an embodiment of the present invention, only the acoustic signal considering economical efficiency is measured.

Power required for the amplification circuit 132 and the frequency filter 133 of the sub sensor unit 130 is supplied from the battery 129 of the main sensor unit 120. The main purpose of the sub-sensor unit 130 is to detect an acoustic signal when a partial discharge occurs, and transmit the detected signal to the main sensor unit 120 to detect the electrical signal. It is configured to estimate the position of the source.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention It will be apparent to those skilled in the art.

110: transformer housing 120: main sensor unit
130: sub sensor unit 140: monitoring device

Claims (6)

A housing constituting the transformer,
A main sensor unit attached to an outer side of the housing to measure an acoustic signal accompanying partial discharge by using a piezoelectric element and a rapid potential change occurring when partial discharge occurs, and analyzing the signal;
And a plurality of sub sensor units attached to the outside of the housing to detect and supply an acoustic signal to the main sensor unit when a partial discharge occurs. The method of claim 1, wherein the main sensor unit
A piezoelectric element attached to a wear plate of the housing and simultaneously detecting an acoustic signal and an electrical signal when a partial discharge occurs in the transformer;
An amplifying circuit for amplifying the acoustic signal and the electrical signal detected from the piezoelectric element, respectively;
A frequency filter for filtering the frequencies of the high frequency signals of the sound signal and the electrical signal amplified by the amplifying circuit, respectively;
A first A / D converter for converting the acoustic signal and the electrical signal filtered from the frequency filter into digital signals, respectively;
A microprocessor which receives the acoustic signal and the electrical signal converted into the digital signal from the first A / D converter, analyzes the factor of each signal, determines whether the actual partial discharge is performed, and finally determines the position of the partial discharge;
A communication module for transmitting the position of the partial discharge determined from the microprocessor to the outside;
A display unit for displaying the position of the partial discharge determined from the microprocessor;
A second A / D converter for receiving the acoustic signals measured from the plurality of sub-sensor units and converting them into digital signals, and a power supply unit for supplying power to each component. Device. The method of claim 2, wherein the sub sensor unit
A plurality of piezoelectric elements attached to the housing through a wear plate to detect an acoustic signal when a partial discharge occurs in the transformer;
An amplifying circuit for amplifying an acoustic signal detected from each piezoelectric element;
And a frequency filter for filtering a signal other than a required frequency band among the sound signals amplified by the amplifying circuit, and transmitting the sound signal filtered from the frequency filter to the second A / D converter of the main sensor unit. Measuring device for internal defects in the transformer. The apparatus of claim 3, wherein the sub sensor unit receives power from a power supply of the main sub unit. The apparatus of claim 2, further comprising a monitoring device configured to monitor a transformer by receiving a generation position of the partial discharge from the communication module of the main sub-unit. 3. The apparatus of claim 2, wherein the piezoelectric element is used in the form of electrodes attached to both surfaces of the dielectric.

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