KR101379201B1

KR101379201B1 - Partical discharge coupler reducing cavity interference

Info

Publication number: KR101379201B1
Application number: KR1020130022165A
Authority: KR
Inventors: 이상화; 선종호; 강동식; 이헌진; 조국희; 황돈하; 송기동; 윤영우
Original assignee: 한국전기연구원
Priority date: 2013-02-28
Filing date: 2013-02-28
Publication date: 2014-03-31

Abstract

The present invention relates to a partial discharge coupler for detecting an abnormality of a power device. The present invention relates to a patch antenna and a patch antenna that detect a partial discharge ultra high frequency (UHF) signal generated inside a power device. It is characterized in that it comprises a cavity (cavity) which is installed to protect the patch antenna, the electromagnetic wave absorber is formed inside the cavity (cavity) to absorb the radio waves.
According to the present invention, the UHF (Ultra High Frequency) signal generated inside the power device is prevented from being scattered by the cavity, thereby improving the sensitivity of the sensor during the partial discharge measurement.

Description

Partial discharge coupler reducing cavity interference

The present invention relates to a sensor for measuring a partial discharge signal generated in the power device, and more particularly to detect the ultra-wideband, ultra-high frequency electromagnetic pulses generated in the internal discharge of the device in order to diagnose the insulation state of the power device For couplers.

Types of partial discharges in power equipment include void discharges that generate voids in the insulator, corona discharges near the tip of the electrode, and creepage discharges along the surface of the insulator. It is a generic term for discharges generated in any part of power equipment such as power receiving facilities and high voltage switchboards installed in various industrial and power system substations.

It is very important to monitor the abnormality of such power equipment and to monitor the degree of deterioration of the insulator and to predict the time of repair, and the measurement and monitoring of partial discharge enables such prediction and management.

For this purpose, partial discharge measuring devices are used in various power devices such as high voltage cables, transformers, and gas insulated switchgears (GIS), and most of the partial discharge measuring devices use the time-based change in measured discharge amount. The insulation diagnosis of the object is performed and technically advanced functions such as the type of discharge and noise cancellation are performed based on the distribution according to the high voltage phase of the measured partial discharge pulses.

Electromagnetic signals generated by internal defects in power equipment can be detected by mounting sensors that react in the UHF (Ultra high frequency: 300 MHz to 3 GHz) band inside or outside the power equipment. UHF Method), which is currently applied to the diagnosis of power equipment, is widely used for monitoring and diagnosing gas insulated switchgear (GIS) at home and abroad.

Ultra high frequency sensors used in the UHF partial discharge detector method are commonly used built-in sensors installed inside the maintenance hall or window in case of gas insulated switchgear (GIS) and external sensors attached to the outside of the spacer. have. Both types consist of an electrode for effectively coupling the electromagnetic wave signal propagating inside the device, and a metal cavity inside and surrounding the electrode.In the case of an external sensor, the cavity interior space is gas insulated. switchgear (GIS) is molded from the same material as the spacer or with a similar dielectric constant.

1 is a diagram illustrating a general structure of an external UHF partial discharge sensor.

The external UHF PD sensor is installed in contact with an outer side of a spacer of a gas insulated switchgear that surrounds the outside of a high voltage current conducting wire.

The internal structure of the external UHF PD sensor consists of a cavity surrounding the outside of a patch antenna that detects discharge propagation in a gas insulated switchgear. have.

A part of the outside of the cavity is provided with a connector, and serves to connect an external measuring device and a sensor.

Using this connector, the voltage generated by the partial discharge of the internal power equipment such as the GIS received by the UHF sensor can be viewed through the external measuring device.

In the case of the built-in sensor, the sensor electrode, that is, the patch antenna, is mainly used in the form of a disk antenna or a top-loaded monopole, and recently, in Korea, a spiral antenna or a flat logarithmic dick is used. Ultra-wideband antennas such as (Log-periodic) are also used as internal electrodes. In general, the shape of the disk antenna matches the polarization of the TEM-mod, which is a basic mode inside a gas insulated switchgear (GIS), which enables effective sensing.In the case of an ultra-wideband flat antenna electrode, an embedded sensor is mounted. It should be accompanied by a careful design that considers the distortion of the field distribution by the gas insulated switchgear (GIS) access window. Electrodes of external sensors are also being applied using various types of patch antennas as internal electrodes.

The metal cavity of the sensor is mounted for the purpose of precisely measuring the internal partial discharge by blocking radiation noise coming directly from the outside of the power device.

However, in general, simply applying the metal cavity to the antenna will change the operation characteristics of the sensor at all, and even if the design considers the cavity, the operating frequency band width that can be secured by the design is reduced. In particular, if the cavity is applied while using the electrode of the broadband antenna type, the operating frequency of the sensor is very narrow, and the sensitivity is very low in the actual partial discharge measurement.

Accordingly, the present invention has been made in view of the above, and the present invention provides a design method for increasing the operating bandwidth of the sensor by reducing the destructive interference caused by the cavity and consequently improving the sensitivity of the sensor during the partial discharge measurement. There is this.

Partial discharge coupler according to the present invention created to achieve the above object is the outside of the patch antenna (Patch Antenna), the patch antenna (Patch Antenna) for detecting the partial discharge ultra-high frequency (UHF) signal generated inside the power equipment It is characterized in that it comprises a cavity (cavity) is installed to protect the patch antenna, a radio wave absorber is formed inside the cavity (cavity) to absorb the radio waves.

In addition, the electromagnetic wave absorber is installed on the remaining inner surface of the cavity except the surface in contact with the power device.

In addition, the electromagnetic wave absorber is characterized in that it is installed only on the opposite side of the surface in contact with the power device.

In addition, the portion provided on the side surface of the cavity of the electromagnetic wave absorber is characterized in that it is installed so as to cover only half of the side surface.

In addition, two pieces of the electromagnetic wave absorbers are provided on the opposite side of the surface where the cavity contacts the power device.

In addition, the electromagnetic wave absorber is characterized in that it is installed in a sheet form.

In addition, the electromagnetic wave absorber is characterized in that it is applied in the cavity (cavity) in the form of a paint.

In addition, the partial discharge coupler is characterized in that for use in the power device abnormality detection system.

According to the present invention, the UHF (Ultra High Frequency) signal generated inside the power device is prevented from being scattered by the cavity, thereby improving the sensitivity of the sensor during the partial discharge measurement.

In addition, there is an effect that the operating frequency of the UHF sensor is widened by alleviating the cancellation interference caused by the cavity (Cavity).

In addition, due to the improved sensitivity of the patch antenna (Patch Antenna), even when the same partial discharge than the conventional UHF sensor receives a larger internal signal, there is an effect that can accurately diagnose the abnormality of the power device.

In addition, there is an effect that the peak voltage sensitivity ratio of the sensor is higher than that of a general metal cavity sensor.

In addition, it is possible to secure an additional center frequency, there is an effect that can more accurately determine the abnormality of the power equipment.

1 is a view showing a general structure of an external UHF partial discharge sensor.
2 is a UHF sensor to which a radio wave absorber is applied in a cavity according to a first embodiment of the present invention.
3 is a UHF sensor according to a second embodiment of the present invention.
4 is a UHF sensor according to a third embodiment of the present invention.
5 is an experimental diagram for evaluation of sensitivity during actual partial discharge of an external type UHF partial discharge sensor.
6 is a graph showing a reflection coefficient measurement result when only the electrode of the bowtie antenna antenna type is provided.
7 is a graph showing a measurement result of a UHF sensor to which only a cavity is applied.
8 is a graph showing reflection coefficient measurement results of a UHF sensor to which a radio wave absorber is applied in a cavity;
9 is a graph showing simulation results of reflection coefficients of a UHF sensor to which a radio wave absorber is applied in a cavity.
10 is a graph of the experiment confirmed the performance of the UHF sensor to which the radio wave absorber is applied compared to the commercial reference sensor.
Figure 11 is a graph of the experiment confirmed the partial discharge of the UHF sensor having a common metal cavity (Cavity) compared to a commercial reference sensor.
12 is a view showing peak voltage sensitivity ratios of a UHF sensor to which a radio wave absorber is applied and a UHF sensor (Cavity Backed Sensor) having a general metal cavity.

2 is a UHF sensor to which a radio wave absorber is applied in a cavity according to an embodiment of the present invention.

The patch antenna 200, which detects partial discharge UHF signals generated inside power devices such as high voltage cables, transformers, and gas insulated switchers (GIS), is a metal cavity ( Cavity, 100 is installed inside. Cavity (100) is mounted for the purpose of blocking the radiation noise flowing from the outside, because the cavity (Cavity, 100) is made of metal and theoretically reflects all the radio waves flowing from the outside.

However, the ultra-high frequency radiated from the power device inside the cavity 100 also strikes and reflects inside the cavity 100 to create scattering of complex radio waves inside the cavity 100. The propagation scattering in the cavity 100 prevents the internal patch antenna 200 from accurately measuring surge current or voltage due to deterioration or sudden abnormality of an insulator in the power device.

Therefore, in addition to removing noise generated outside, the noise inside the cavity 100 plays an important role for the patch antenna 200 to accurately measure the abnormality of the power device.

The present invention uses a method of installing the radio wave absorber 300 inside the cavity (Cavity, 100) to remove such internal noise.

The electromagnetic wave absorber 300 is attached to the side and the bottom in the form of a sheet inside the cavity (Cavity, 100). However, it may not necessarily be attached in the form of a sheet, and may be formed by applying the radio wave absorber 300 to the inside of the cavity 100 in the form of a paint.

The electromagnetic wave absorber 300 absorbs UHF (Ultra High Frequency) signals generated inside the power device. Therefore, unlike when there is only the metal cavity (Cavity, 100), the radio wave that strikes the inside of the cavity (Cavity, 100) is absorbed by the radio wave absorber 300 without being reflected again and disappears. Therefore, the patch antenna 200 may receive the pure UHF (Ultra High Frequency) signal generated from the power device and measure the value without being affected by the scattered radio waves inside the cavity 100. Therefore, it is possible to accurately detect an abnormality in a power device such as a gas insulated switcher (GIS).

The radio wave absorber 300 used above is made of a mixture of ferrite, rubber, carbon, polyurethane, silicon, etc., and various radio wave absorbers are made. Various radio wave absorbers 300 may be used in the present invention.

3 is a UHF sensor according to a second embodiment of the present invention.

In the case of FIG. 3, the radio wave absorber 300 is provided only on the opposite side of the surface on which the patch antenna 200 is installed. That is, only the bottom surface of the cavity (Cavity, 100) is installed. However, it should be noted that the lower surface in the present specification means the lower surface in the drawings, and may be the upper surface depending on the position where the UHF sensor is installed.

FIG. 4 is a UHF sensor according to a third embodiment of the present invention, in which only half of the side surface of the cavity (Cavity) 100 is wrapped in the radio wave absorber 300.

In addition, in the drawings of FIGS. 2, 3, and 4, an embodiment in which the sheet of the electromagnetic wave absorber 300 is further provided on the lower surface may be considered.

The reason why the radio wave absorber 300 is installed in various ways is that various embodiments are required to effectively absorb the radiation noise generated from the inside depending on the power device in which the UHF sensor is used. Therefore, the radio wave absorber 300 may be installed inside the cavity 100 in various forms in addition to the formats of FIGS. 2, 3, and 4, and one of ordinary skill in the art may be naturally derived. Therefore, obviously not limited to the embodiment of the present invention.

In addition, in the present invention, the embodiment of the present invention has been described as a method of installing the electromagnetic wave absorber 300 sheet having a thickness of 2 mm inside the cavity 100, but the UHF sensor according to the present invention may be used in various ways. The thickness can be adjusted.

5 is an experimental diagram for evaluation of sensitivity during actual partial emission of an external UHF partial discharge sensor.

Test sensor (Sensor # 1, Test) and reference sensor (Sensor # 2, reference) on the spacer (2) outside the GIS (Gas Insulation Switchgear) that surrounds the conductive wire with high voltage Install a partial discharge generator (PD Cell) capable of generating a real partial discharge in a portion away from the sensors at a predetermined position, and apply a high voltage.

The voltage generated by the PD cell is measured by a sensing device such as an oscilloscope connected to the outside through a test sensor (Sensor # 1, Test) and a reference sensor (Sensor # 2, reference). . These experiments were produced in accordance with the recommendations of the International Institute of Power Engineering (CIGRE), and detailed test methods can be found in Korean Patent Publication No. 10-0666505.

In the experiment of FIG. 5, the UHF sensor used for the test is a UHF sensor in which a sheet of the radio wave absorber 300 is further installed on the lower surface of the UHF sensor according to the embodiment of FIG. 4.

The thickness of the sheet was experimented with 2 mm, and the electromagnetic wave absorber 300 was experimented with a ferrite core or Mn-Zn-based ferrite mixed with rubber. In addition, in the experiment according to an embodiment of the present invention, the radio wave absorber 300 is attached to the inside of the cavity (Cavity, 100) in the form of a sheet, but the experiment is not necessarily limited thereto. Can be.

First, in order to verify the effect of the UHF sensor used in the test, only the patch antenna (Patch Antenna, 200) and the patch antenna (Patch Antenna, 200) is further provided with a cavity (Cavity, 100) and the cavity (Cavity, The case where the radio wave absorber 300 is provided in 100 was set as a comparative example and the measured sensitivity of each experiment was compared through the reflection coefficient.

6 is a graph of reflection coefficient measurement results when the external UHF sensor includes only an electrode of a bowtie antenna antenna type.

If there is only an antenna without cavity, wideband single resonance is performed in the center frequency of 2.3 GHz band.

However, since the resonance characteristics are changed while installing the cavity outside, the resonance is narrowed at the center frequency of 1.7 GHz and the bandwidth is narrowed as shown in FIG. 7. This is because the offset interference caused by the cavity (cavity) occurs, the sensitivity is lowered.

Due to the above results, it may be determined that not applying a cavity is desirable to secure a wider operating frequency of the UHF (Ultra High Frequency) sensor, but it should be noted that the result of FIG. 6 is an experimental result. .

In the experimental environment, it is possible to secure the operating frequency band by the performance of the antenna itself since the influence of external radiation noise is small. However, in the real environment, the performance of the antenna may be degraded due to various electronic devices or naturally occurring noise radiation. have.

Therefore, in actual operation of the UHF (Ultra High Frequency) sensor, a cavity must be provided to prevent performance degradation of the antenna due to external noise.

However, due to the installation of the cavity (cavity), the resonance characteristic is completely different, it is obvious that the sensitivity of the ultra high frequency (UHF) sensor is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and is intended to secure a wider operating frequency of a UHF (Ultra High Frequency) sensor while reducing the influence of external radiation noise by installing a cavity outside the antenna.

To this end, the present invention is provided with a radio wave absorber inside the cavity (Cavity).

8 is a graph showing a reflection coefficient measurement result of a UHF sensor to which a radio wave absorber is applied in a cavity.

Through the experimental graph of FIG. 8, it can be seen that the operating frequency has been widened to the center frequency of 1.8 GHz. In addition, an additional operating frequency of 1.4 GHz was secured. Through this, it can be seen that by providing a radio wave absorber, the offset interference caused by the cavity is alleviated, thereby improving the sensitivity of the UHF sensor.

9 is a graph showing simulation results of reflection coefficients of a UHF sensor to which a radio wave absorber is applied in a cavity.

Through the simulation of FIG. 9, a patch antenna, a cavity, and an absorber were all predicted without directly fabricating the characteristics of the sensor, and thus, the partial discharge coupler according to the present invention could be freely designed.

10 and 11 are other experiments in which the UHF sensor according to the present invention is compared with a commercial reference sensor and a sensor having a general metal cavity, in which the bandwidth measured by the reflection coefficient (Fig. 8) is a simple heat loss of the radio wave absorber. It is an experiment to check whether the sensitivity is increased by increasing or absorbing the actual partial discharge.

10 is a graph of an experiment confirming the performance of the UHF sensor to which the radio wave absorber is applied in comparison with a commercial reference sensor.

In the graph, yellow is the waveform measuring the partial discharge of the sensor to which the radio wave absorber is applied, and blue is the waveform measuring the partial discharge using a commercial reference sensor. Comparing the two graphs, it can be seen that the UHF sensor with the radio absorber has improved the performance compared to the commercial reference sensor, as yellow is receiving a larger pulse for the partial discharge of the same size.

FIG. 11 is a graph illustrating partial discharge of a UHF sensor having a general metal cavity compared with a commercial reference sensor.

Yellow is the waveform of the partial discharge measured by a UHF sensor with a common metal cavity, and blue is the waveform of the partial discharge pulse using a commercial reference sensor. Both sensors measured the same partial discharge pulses, but the commercial reference sensor measures larger pulses, indicating better sensitivity.

10 and 11, it can be seen that the reference sensor according to the present invention shows better sensitivity than a commercial reference sensor or a sensor having only a general metal cavity.

FIG. 12 is a table illustrating peak voltage sensitivity ratios of the UHF sensor to which the radio wave absorber is applied and the UHF sensor having a general metal cavity.

The results are summarized through 100 experiments, and the UHF sensor with a radio absorber shows a voltage sensitivity ratio of 1.03 for a UHF sensor with a general metal cavity, and shows a voltage sensitivity ratio of 0.8. .

Accordingly, it can be seen from the results of FIGS. 10 and 11 that the UHF sensor according to the embodiment of the present invention effectively removes the interference from the inside of the cavity in addition to the noise emitted from the outside, thereby showing more excellent reception sensitivity.

On the other hand, the present invention is not limited to the embodiments described, it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention.

Therefore, it should be said that such modifications or modifications belong to the claims of the present invention.

100: Cavity
200: patch antenna
300: radio wave absorber

Claims

A patch antenna for detecting a partial discharge ultra high frequency (UHF) signal generated inside the power device;
A metal cavity installed to protect the patch antenna from the outside of the patch antenna and having an opening formed at a surface contacting the power device; And
And a radio wave absorber formed inside the metal cavity except for the opening of the metal cavity to absorb radio waves.

The method of claim 1,
The electromagnetic wave absorber is installed only on the opposite side of the surface in contact with the power device.

The method of claim 1,
The electromagnetic wave absorber is installed on the opposite side of the surface in contact with the side surface of the cavity, the portion installed on the side surface of the cavity is installed to cover only half of the side surface.

4. The method according to any one of claims 2 to 3,
A partial discharge coupler, in which two pieces of the electromagnetic wave absorbers are installed on a surface opposite to a surface where the cavity is in contact with the power device.

5. The method of claim 4,
The electromagnetic wave absorber is a partial discharge coupler is installed in the form of a sheet.

5. The method of claim 4,
And the electromagnetic wave absorber is applied in the cavity in the form of a paint.

The method of claim 1,
Power device fault detection system having the partial discharge coupler.

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