KR100666505B1 - External Sensor for Diagnosis Partial Discharge of Gas-Insulated Switchgear - Google Patents

Abstract

The present invention relates to an external partial discharge detection sensor of a gas insulated switchgear, which is installed outside a GIS (Gas Insulated Switchgear) spacer and a patch antenna for detecting a partial discharge UHF signal generated in the GIS ( (Patch Antenna) is provided, the patch antenna is accommodated and the appearance is composed of a metal shielding material for minimizing external noise due to exposure, the insulator for fixing the patch antenna is an external type of gas insulated switchgear filled inside the metal shielding material In the partial discharge detection sensor, the patch antenna is installed in the detection window of the GIS to detect the partial discharge signal of 5pC, the length of the antenna is proportional to the half wavelength (λ / 2) as a function of the frequency, omni-directional radiation Dipole patch antenna having a characteristic; A Fat dipole patch antenna having a modified length of the dipole patch antenna and having the same length and width; A pair of planar logarithmic periodic patch antennas that periodically vary as a logarithm of frequency with a wideband antenna element; An conformal spiral patch antenna having a geometry in which the conductor surface is expressed as an angle; And a spiral patch antenna that is linearly proportional to polar with respect to the conformal spiral and has a frequency independence characteristic, thereby detecting and detecting partial discharge of the gas insulated switchgear.

 Gas Insulation, Switchgear, Sulfur Fluoride, Partial Discharge, Detection Sensor, Ultra High Frequency, Broadband

Description

External Sensor for Diagnosis Partial Discharge of Gas-Insulated Switchgear}

1A is a view illustrating an internal electric field and an internal phenomenon when partial discharge occurs due to an enclosure fixing protrusion inside a general gas insulated switchgear.

1B is a graph showing a current pulse by a typical partial discharge.

2 is a view showing the electromagnetic wave propagation and transmission state inside the gas insulated switchgear (GIS).

3 is a diagram illustrating an electromagnetic wave generation, a traveling path, and a detection method inside a GIS.

4A through 4D are diagrams illustrating a spiral linear antenna.

Figure 5a shows a spiral plate, Figure 5b illustrates a slot antenna.

FIG. 6A illustrates a planar logarithmic periodic antenna, and FIG. 6B illustrates a lead logarithmic periodic antenna.

FIG. 7A illustrates a trapezoidal saw blade planar logarithmic periodic antenna, and FIG. 7B illustrates a trapezoidal saw blade leaded logarithmic periodic antenna.

8 is a view showing the structure of an external sensor as an embodiment of the present invention.

9A to 9B are views illustrating a structure of a patch antenna applied to an external sensor.

FIG. 10 is a graph comparing a measured value and a reflection loss (RL) calculation value of a patch antenna applied to an external sensor.

11 is a diagram illustrating an external sensor for an actual scale GIS.

FIG. 12 is a graph comparing the calculated RL (reflection loss) calculated value and the measured value according to the structure of a patch antenna applied to an external sensor.

FIG. 13 is a graph illustrating RL characteristics in the presence of a free space and a metal case of a dipole patch antenna; FIG.

14 is a graph illustrating RL change of a dipole patch antenna installed in a free space.

FIG. 15A shows a partial discharge generator, and FIG. 15B is a graph showing the apparent discharge amount 5pC.

16 is a diagram illustrating an actual scale GIS mockup for performance test of an external sensor.

17 is a configuration diagram of an external sensor test apparatus.

18A to 18E are graphs comparing RL of an external UHF (ultra high frequency) sensor.

19A to 19E are graphs comparing frequency response characteristics of an external UHF sensor.

20A to 20E are graphs illustrating waveforms of measurement of partial discharge signals of an external UHF sensor.

The present invention relates to an external partial discharge detection sensor of a gas insulated switchgear, and more particularly, to a high-sensitivity ultra-high frequency sensor that detects and detects a partial discharge of a SF ₆ (sulfur fluoride) gas insulated switchgear used as a power equipment. It is about.

SF ₆ Gas-Insulated Switchgear (GIS) is a power equipment with excellent dielectric strength, breaking performance and reliability. In case of a failure, the economic effect of the ripple effect is very high. At present, technology development and efforts to prevent GIS accidents are steadily progressing, and on-site application technology is proposed and applied in very few countries such as Europe and Japan. However, the state-of-the-art technology is not only because of high technical barriers, but also somewhat lacking in actual field application, the application is not universal.

Conventionally, as a power facility in Japan, a test three-phase substation was constructed in order to upgrade the system's maximum voltage from 500 kV to 1,000 kV and has been in trial operation for a long time since 1996. Operational accidents occurred during the test operation of the 1,000kV transformer and GIS developed by the company, and the performance of these devices is continuously verified and supplemented. Moreover, numerous research institutes have applied various methods to detect internal defects of GIS.

Meanwhile, in the UK and Japan, UHF (Ultra High Frequency) diagnostic technology has been developed, and in Sweden and Norway, research is being conducted on acoustic signal diagnosis technology.

As a result, intensive efforts have been focused on CIGRE (International Power Engineering Conference) to select suitable technologies for field application. As a result, the CIGRE specialized group uses UHF diagnostic method as electrical method and mechanical method. Recommends a combination of acoustic signal diagnostics.

In particular, the UK's Diagnostic Monitering System (DMS) was the first company to develop UHF technology. Starting in the early 1980s, all GISs introduced in the UK since 1988 standardized the inclusion of UHF sensors. In light of these technical trends, there is an urgent need for a diagnosis technology that can always monitor the status of the GIS by measuring signals in the UHF band generated by partial discharge.

Insulated with sulfur fluoride (SF ₆ ) When partial discharge is generated in the GIS, the partial discharge pulse is a pulse having a steep rise time of several ns and is known to contain a frequency component of several hundred MHz to several kHz. Electromagnetic signals generated by GIS internal defects are accompanied by complex resonance, reflection and attenuation and propagate inside the GIS. The electromagnetic wave signal propagated from the inside can be detected by mounting a sensor that reacts in the UHF band in the GIS or externally, which is called the UHF partial discharge detector method (UHF method).

)에 따라 결정된다.In the related art, FIG. 1A illustrates an internal electric field and an internal phenomenon when partial discharge occurs due to the GIS internal enclosure fixing protrusion, and FIG. 1B shows a typical current pulse waveform. When partial discharge occurs in the GIS, a transient electric current having a very fast rise time of several tens of ps flows in the GIS, as shown in FIG. 1B. In this case, assuming that the current pulse is a Gaussian pulse, and the pulse width is 1 ns, the frequency distribution of the current pulse is distributed from DC to 1 GHz band, and the electromagnetic pulse reaches 20 GHz due to the current pulse. Is radiated. Here, the power of the electromagnetic wave (power, P _EM ) and the frequency (f _EM ) are respectively the magnitude of the current pulse (i _t ), the rise of the current pulse, and the rate of change of the current at the falling portion (

Is determined by).

As described above, the ultra-high frequency signal radiated by the partial discharge current propagates in the form of frequencies with different wavelengths along the inner conductor, and the electromagnetic waves are dispersed and propagated due to reflection, thereby interfering between signals. This occurs and propagates by attenuation as it encounters a medium that is delayed or has a different dielectric constant (eg, a spacer).

The GIS chamber structure can be assumed to be a transmission line in the form of coaxial electrodes acting as a low loss waveguide for UHF signal transmission, so if there is no spacer or discontinuity, a 1 GHz signal in the case of a 0.5 m radius waveguide The propagation loss of is theoretically only 3-5dB / km. However, due to the complex structure inside the GIS and the reflection caused by numerous discontinuities, the generated signal has attenuation and resonance of about 2dB / m.

로 감소된다. 여기서

는 스페이서 절연체(에폭시)의 비유전율이다. GIS 내부 구조의 불균일에 의해 UHF 신호는 복잡한 형태의 반사를 일으키며, 이에 의한 효과는 이론적으로 분석될 수 없지만 크게 단순화시켜 표현할 수 있다.The UHF signal generated by such a defect propagates inside the GIS chamber while rapidly attenuating the portion of the signal that falls below the cutoff frequency for each mode. The signal propagates along a feed line in the form of a coaxial electrode at a speed close to the speed of light.

Is reduced. here

Is the dielectric constant of the spacer insulator (epoxy). UHF signals cause complex reflections due to non-uniformity of the GIS internal structure, and their effects cannot be analyzed theoretically but can be greatly simplified.

Figure 2 shows the electromagnetic wave propagation and transfer state inside the GIS, the electromagnetic wave generated inside the GIS proceeds along the feed line of the SF ₆ gas and coaxial electrode starting from the point where the partial discharge occurs. Ongoing electromagnetic waves reach the metal enclosures, spacers and inspection windows. Electromagnetic theory states that in the case of a complete conductor, all components of the system must be zero in the region inside the conductor. Therefore, the electromagnetic waves that reach the GIS enclosure are not transmitted but are internally reflected inside the GIS.

Electromagnetic waves propagated through the spacer pass through a medium (spacer) having a different dielectric constant from that of SF ₆ gas, so that some of them are reflected and some are transmitted by the difference in dielectric constant. The reflected electromagnetic waves are present inside the GIS of the bay before being transmitted and the electromagnetic waves passing through the spacer are present inside the next bay GIS or radiated into the air. The electromagnetic waves generated by the partial discharge decrease the electromagnetic energy by repeating reflection and transmission every time they pass through the spacer, and eventually become attenuated and extinguished.

Partial discharge measurement by electromagnetic wave detection method detects Ultra Wide Bandwidth (UWB) Electro-Magnetic Wave (EM Wave) signal due to partial discharge in ultrahigh frequency band (300MHz ~ 3GHz). This makes it possible to measure the partial discharge in the field with high sensitivity, resulting in the determination of the defect location.

Ultra-high frequency sensors can be classified into internal type attached to GIS maintenance hall or window and external type attached to open or closed spacers. Depends. The ultra-high frequency sensor used in the early stage of development has the structure of a single disk type detection unit using the principle of capacitive coupler, and the electromagnetic wave is detected by using the principle of resonance in a single frequency band. . This single disk type ultra-high frequency sensor is a narrow bandwidth (narrow bandwidth; Δf ≤ 1.5f _c , f _c ; center frequency) sensor, which is limited in the frequency analysis of radiated electromagnetic waves by partial discharge. Since the metal disk was exposed to the SF ₆ gas inside the inspection window, the risk of breakdown of the metal disk as a detection part was raised when a high field was applied.

In order to solve this problem, studies using an ultra wide-bandwidth (Δf> 1.5f _c ) or frequency independent patch type antenna as an ultra-high frequency sensor have been actively conducted.

As described above, when the ultra-high frequency signal emitted by the partial discharge current reaches the inspection window after reaching the GIS waveguide, the medium is different, so that some parts are reflected and some are transmitted by the difference in dielectric constant. The reflected electromagnetic waves exist inside the GIS and the transmitted electromagnetic waves are emitted into the air.

As a result, among the partial discharge signals generated due to a defect in the GIS, the electromagnetic signal passes through the spacer or the inspection window while the internal structure of the GIS is transmitted as a transmission medium, and the electromagnetic signal can be detected through the external UHF sensor. Some reflected electromagnetic waves can be detected by the built-in UHF sensor. 3 shows the generation, progress and detection path of electromagnetic waves.

An object of the present invention is to provide an external sensor that is installed outside the spacer of the gas insulated switchgear as the ultra-wideband sensor.

Furthermore, another object of the present invention is to provide a patch antenna having various shapes and performances mounted on an external sensor.

In order to achieve the object according to the present invention, a patch antenna is installed outside the GIS (Gas Insulated Switchgear) spacer to detect a partial discharge UHF (Ultra High Frequency) signal generated inside the GIS, In the external partial discharge detection sensor of the gas insulated switchgear which the patch antenna is accommodated and the exterior is made of a metal shielding material for minimizing external noise by exposure, and the insulator for fixing the patch antenna is filled inside the metal shielding material,

The patch antenna detects a partial discharge signal of 5pC,

A dipole patch antenna having a omnidirectional radiation characteristic whose length of the antenna is proportional to the half wavelength [lambda] / 2 as a function of frequency;

A Fat dipole patch antenna having a modified length of the dipole patch antenna and having the same length and width;

A pair of planar logarithmic periodic patch antennas that periodically vary as a logarithm of frequency with a wideband antenna element;

An conformal spiral patch antenna having a geometry in which the conductor surface is expressed as an angle; And

An external partial discharge detection sensor of a gas insulated switchgear having any one of spiral patch antennas linearly proportional to a polar angle and having a frequency independence with respect to a conformal spiral is provided.

Hereinafter, the external partial discharge detection sensor of the gas insulated switchgear according to the present invention will be described in detail with reference to the accompanying drawings.

First, in the present invention, various types of external UHF sensors that can be applied to a real scale, for example, 170kV mock-up GIS, are designed to be applied to 170kV GIS and tested for their fabrication and performance. . In addition, the patch antenna embedded in the external sensor was designed using a broadband antenna element, and the characteristics of the sensor were confirmed using a 3D high frequency electromagnetic field analysis tool. Various kinds of patch antennas were designed for each sensor, and the return loss (RL) characteristics of the sensors were compared according to the shape. Also, 170kV class GIS mock-up sensor was installed at actual scale to install 5pC according to IEC 60270. By measuring and comparing the detection frequency characteristics and peak power of the sensors with respect to the Partial Discharge (PD) signal, the type of patch antenna most suitable for the correlation and installation structure for each characteristic is selected and It is applied.

On the other hand, the basic characteristics and design elements for a log-spiral patch antenna and a log-periodic patch antenna having a bandwidth of 40: 1 or more applied to the design of an external sensor of the present invention will be described. .

In general, a broadband antenna refers to an antenna having a wide bandwidth, but the term 'wideband' is a relative measure of bandwidth and thus varies according to various conditions. The bandwidth is represented by the ratio of the upper limit value f _u and the lower limit value f _L of the operating frequency. Assuming that the center frequency (or design frequency) is f _C , the bandwidth B _p for the center frequency is given by the following equation.

[Equation 1]

The bandwidth B _p is also defined by the ratio B _{r and} is given by the following equation.

[Equation 2]

The bandwidth of the narrowband antennas is expressed in percentage using Equation 1, while the broadband antennas are quoted in ratio using Equation 2.

If the impedance and pattern of the antenna do not vary significantly for approximately one octave (f _U / f _L = 2) or more, it is classified as a broadband antenna.

However, UHF sensor applied to GIS should be able to detect electromagnetic signal for frequency band over 1GHz in the range including ultrahigh frequency band (300MHz ~ 3GHz), so ultra wide band (UWB) with bandwidth over 40: 1 Antenna is required.

A Log-Spiral Antenna is a geometry in which the conductor plane is expressed in degrees. Thus, any requirements for the form that can be used to design a wideband antenna can be met. Since the curve along the surface is infinitely long, it is necessary to determine the length for finite lengths. The lowest operating frequency is when the entire length is equal to the wavelength. At frequencies above the optimum operating frequency, the radiation pattern and impedance characteristics are frequency independent.

The interpretation of the broadband antenna introduced by Rumssey and simplified by Elliott follows the following assumptions for the best explanation in the sphere coordinate system (r, θ, φ).

1. The antenna has two terminals that approach the origin indefinitely.

2. Antenna terminals are symmetrical with θ = 0 and π axes, respectively.

3. The antenna is a perfect conductor and is surrounded by an infinitely uniform isotropic medium.

According to the above assumption, the antenna conductor surface or edge may be well represented by a curve as in the following equation.

[Equation 3]

Here, r is the distance between the conductor surface or the edge, and the general solution of Equation 3 is as follows.

[Equation 4]

The conformal spiral curve can be derived by setting the derivative of Equation 4 as follows.

[Equation 5]

Where A is a constant and δ is a Dirac delta function. Using Equation 5, Equation 4

[Equation 6]

Becomes Where A is

[Equation 7]

In terms of wavelength, Equation 6 can be written as follows.

[Equation 8]

Where φ ₁ is

[Equation 9]

to be. Another form of Equation 6 is as follows.

[Equation 10]

Here, 1 / a is the expansion ratio of the spiral, and ψ is an angle formed by the tangent of the radial distance p and the spiral as shown in FIG. 4A. And it is clear from Equation 8 that the change in wavelength is equal to the change in φ ₀ which merely rotates the pattern of infinity structure. Therefore, similar characteristics can be seen in the finite structure within the range determined by the length of the antenna.

The same result can be obtained by examining Equation 10. The C ₀ that by increasing the frequency in logarithmic (ln f) the same as for rotating the structure by C ₀ tanψ. As a result, the radiation pattern only rotates and does not change. Thus, you get an antenna that is independent of frequency.

Moreover, the total length L of the spiral

[Equation 11]

Can be calculated by using Equation 8,

[Equation 12]

Same as Where ρ ₀ and ρ ₁ are the radius inside and outside the spiral.

일 때이다. 이외에 여러 가지 구성이 가능하다.Various structures of spirals are used to make different types of antenna systems. When φ ₀ is 0 and π in Equation 6, the linear spiral antenna is in the form of FIG. 4B, and the structures of FIGS. 4C and 4D are

When Many other configurations are possible.

The conformal metal surface denoted by P can be expressed by using Equation 6 to express the edge curve as follows.

[Equation 13]

[Equation 14]

과 K는 각각From here,

And K are respectively

[Equation 15]

[Equation 16]

to be.

The two curves, specified as the edges of the conductor surface, have the same shape when zoomed in toward the opposite side or rotated by an angle δ. Magnification or rotation is also applied to the conductor element P having a finite width as in FIG. The counter element Q may be expressed by the following equation.

[Equation 17]

과

는 각각Where, here,

and

Are each

Equation 18

[Equation 19]

는, Where

Is

[Equation 20]

to be.

, 단자의 길이 ρ₂ 로서 나타낸다. 또한 각 도체는 종단에서 정합이 잘 되도록 도 5a의 점선으로 표시된 것처럼 끝에서 테이퍼져 있다.The system consisting of two conductors P and Q constitutes an equilibrium system as shown in FIG. 5A. The length of the finite structure is shown as a fixed length L _{0 which} is spirally formed along the center line of the conductor. The overall structure of the antenna is the rotation angle δ, conductor length L ₀ , spiral expansion rate

, The length of the terminal ρ ₂ . Each conductor is also tapered at the end as indicated by the dashed line in FIG. 5A so that it is well matched at the end.

5B is a structure with a spiral slot over a large conductor plane and tapered for termination matching. Slot antennas are most practical because they are easily fed by balanced coaxial feeding to maintain overall balance.

Spiral slot antennas with good radiation characteristics can be made from 1/2 to 3 turns. The optimal design is about 1.25 to 1.5 laps, with a total length of one wavelength or more. Expansion rates should not exceed 10 per turn. The radiation pattern should be maximum in both directions perpendicular to the antenna plane and zero in the direction defined by the infinite structure. The radiated radio waves radiate in circular polarization near the axis of the main lobe at the available bandwidth. When cutting off the tip, the beam width changes with frequency due to the rotation of the pattern.

In general, however, slot antennas that have wider antenna widths and closer spiral spacings have smoother, more uniform radiation patterns with small variations in beam width with frequency. In the case of a symmetrical configuration, the directivity of the radiation pattern is not inclined and is also symmetrical.

As another antenna independent of frequency change, the Log-Periodic structure introduced by DuHamel and Isbell is completely independent of frequency because the entire structure of the antenna cannot be expressed entirely by angle. I can not say.

The current distribution of the planar logarithmic periodic antenna plane in FIG. 6A shows that the electric field on the conductor decays very rapidly with distance, which means that the current mostly concentrates at or near the edge of the conductor. Therefore, in order to make a linear antenna as shown in FIG. 6b, a linear antenna having the same structure as the shape of the edge of the conductor plane is made and tested, and the performance is almost the same as in FIG. 6a. Therefore, the linear structure is characterized by structurally simpler, lighter, more economical and wind-resistant than the flat plate. The same non-planar structure made by bending both elements into a V-shape is also widely used.

In FIG. 6, when the edge or line of the flat plate is straightened to form a straight line, a trapezoidal saw blade logarithmic periodic structure as shown in FIG. 7 is obtained. This simplified structure is somewhat convenient to manufacture without degrading the properties. There are many algebraic periodic antennas that are unusual in form, including algebraic periodic array structures. In the structure of Figure 7, if the saw blade is made of the same period the ratio of the logarithmic period is

[Equation 21]

And the width of the antenna slot is

[Equation 22]

Same as τ represents the magnitude ratio. If f ₁ and f ₂ are separated by one period, τ is related to frequency as follows.

[Equation 23]

Extensive studies have been made on the properties determined by α, β, τ and χ at the antenna in FIG. 7B. In general, these structures have almost the same performance as flat and conical structures. The difference is that the logarithmic periodic structure is linearly polarized instead of circularly polarized.

As a structure of an external sensor applied to the present invention, FIG. 8 is an antenna type sensor that detects a partial discharge signal generated by a GIS internal defect in a form mounted outside the GIS spacer through a patch antenna embedded in the sensor. In order to minimize the influence of external noise caused by exposure, the exterior is shielded with a metal shield case, and the inside of the sensor is filled with an insulator for fixing a patch antenna.

8 is a basic structure of an external sensor, and design elements that influence the characteristics of the sensor are as follows.

1. Structure of Patch Antenna

2. Distance between spacer and patch antenna

3. The dielectric constant of the internal insulator (ε _r )

Therefore, by properly adjusting these components, it is possible to design the sensor optimized in the desired frequency band.

In the present invention, the sensor was designed based on the actual scale of 170kV GIS, and the appearance and internal insulator of the sensor were changed while changing the shape of the patch antenna and analyzed the characteristic change of the sensor according to the patch antenna structure.

In the design and fabrication of the patch antenna of the external sensor, various types of patch antennas were designed to compare different antennas with respect to the characteristics of the dipole antenna, which is the most basic antenna type, and the modified patch was compared Fat-Dipole, same width W and length L, a pair of flat log-periodic patch antennas, spiral patch antennas, and conformal spirals that are widely used as broadband antenna elements. Spiral) patch antenna was designed and fabricated.

The patch antenna structure of the external sensor is shown in FIGS. 9A to 9E. Each antenna element is arranged to minimize the coupling between the metal case and the magnetic field formed in the antenna and to increase the detection sensitivity.

In addition, the patch antenna has a width, a length, and a thickness of 40 mm, 106 mm, and 1.6 mm, respectively, and a dielectric constant ε _r = 4.4 (FR4) substrate was used. The return loss RL of each patch antenna is shown in the graph of FIG. 10. In the case of the basic dipole patch antenna of FIG. 9A, resonance occurred at 2.7 GHz due to size limitation, and the case of the modified pet dipole patch antenna of the dipole patch antenna of FIG. 9 b is widely distributed over 1 to 3 GHz.

Furthermore, FIG. 9F shows the size of the substrate and the parameters of the pad dipole for the manufacture of the pad dipole patch antenna. In other words, the dipole has a square shape. The dipole width W of the pad dipole patch antenna is preferably 18 mm, the length L is 18 mm, and the distance d between the dipoles is 2 mm. The substrate size is 40 mm in width SW and 106 mm in length SL, and is rectangular in shape.

In addition, the pair of flat logarithmic periodic patch antennas of FIG. 9C achieve multiple resonances, but show a low return loss of less than -3 dB at 500 MHz to 3 GHz. As a result of FIG. 10, the logarithmic periodic patch antenna, the conformal spiral patch antenna and the pad dipole patch antenna have the most suitable RL characteristics for application as an external sensor.

로서 0.86이고, 기판 크기는 너비(SW) 40mm에 길이(SL) 40mm로서 직사각형의 형태이며, 기판의 두께는 1.5mm이다.Furthermore, FIG. 9G illustrates the size of the substrate and the dipole parameters for the fabrication of a pair of planar logarithmic patch antennas, and the slot width of the pair of planar logarithmic patch antennas.

It is 0.86, and the substrate size is 40 mm in width (SW) and 40 mm in length (SL) in the form of a rectangle, and the thickness of the substrate is 1.5 mm.

The length L ₀ of the inner side of the antenna saw blade is 20 mm, the outer length L ₁ of the saw blade is 44 mm, the relative dielectric constant? _R of the substrate is 4.4 (FR4), and the center terminal distance is preferably 2 mm.

The external sensor is designed for a 170kV class GIS, and the external appearance of the sensor is shielded by a metal case, and the surface on which the sensor is mounted is manufactured in an annular shape so as to be suitable for a spacer surface.

The external sensor is shielded by a metal case, which is different from the free space characteristic of a general antenna. For efficient design and verification, the RL values obtained using the high frequency electromagnetic field analysis program are compared with those measured by the actual sensors.

12 is a result of comparing the RL measurement value and the calculated value of the external sensor with a built-in patch antenna. In FIG. 12, the solid line represents the measured RL value, and the dotted line represents the calculated value. As a result of FIG. 12, the calculated RL value of the dipole patch antenna and the resonance characteristics of the actual manufactured RL value are almost the same. In other structures, the resonance characteristics are similar, but the cause of the error is clearly It is determined that the coupling structure between the antennas and the case and the feeding structure for measuring the RL value in the actual antenna and the simulation model are different.

In the patch antenna mounted on the external sensor, the RL value is changed by the relative dielectric constant of the metal case of the sensor and the internal insulator. FIG. 13 shows the difference in characteristics between the free space and the metal case of the basic dipole patch antenna. In the presence of a metal case, the resonance point of the patch antenna shifted to a band as low as 1 GHz due to the relative dielectric constant of the internal insulator (ε _r = 3-4), and another resonance characteristic appeared at 1.2 GHz by coupling with the metal case. .

When the patch antenna whose characteristics are changed by the metal case and the internal insulator is installed in the spacer, the reflection loss RL is changed again by the relative dielectric constant (epoxy) of the spacer insulator. 14 is a RL change of the dipole patch antenna sensor by the spacer insulator. It can be seen that the resonance point of the sensor moves to a low band of about 500 MHz (1.2 GHz => 700 MHz) by the relative dielectric constant of the spacer insulator.

On the other hand, with respect to the external sensor according to the present invention is provided with a device for the characteristic test, it will be described.

First, the characteristic test of the sensor can be classified into three types. The first is a return loss (RL) measurement to evaluate the performance of the sensor itself. The second is the response characteristic of the sensor's detection frequency band (500MHz to 1.5GHz), and the third is the sensitivity of the sensor. Sensitivity and Peak Power measurements.

In the case of the return loss, since the RL of the sensor itself and the RL when the sensor is installed in the GIS are different, the sensor must be measured while the sensor is installed in the GIS to evaluate the RL performance of the final sensor. In addition, in order to measure the frequency response characteristics and the output of the sensor, a discharge source capable of generating a constant partial discharge signal is required. CIGRE recommends that an apparent discharge amount of 5pC be measured for systems measured with electromagnetic waves. Therefore, a partial discharge generator (PD-Cell) was fabricated to generate an apparent discharge amount of 5 pC. The manufacture of the partial discharge generator should be consistent with the discharge amount (5pC) according to the recommendations of CIGRE, and was manufactured as shown in FIG. 15A in consideration of the type of discharge that can be generated in the GIS.

And 15b is a graph measuring the apparent discharge amount of 5pC by the IEC 60270 fabricated partial discharge generator. Inside the partial discharge generator was put a metal-type (ball-type), the internal pressure was 0.5MPa SF6 gas was applied to the same as the actual GIS pressure. The frequency response characteristics can be compared by calculating the channel power after measuring the frequency spectrum of the sensor for the partial discharge signal inside the GIS. The channel power is average power in the detection frequency band (500 MHz to 1.5 GHz) of the sensor and can be obtained by the following equation.

[Equation 24]

Where CP = Channel power (dBm), CHBW = Channel bandwidth (kHz), RBW = Resolution bandwidth in kHz used for measurement, k _n = Noise used for RBW Correction factor for the bandwidth, where N = number of pixels in the channel, P _i = Level at which dBm is replaced by pixel i, and a _{i (RRC)} = RRC filter Attenuation.

As an external sensor manufactured according to the present invention, in order to measure the return loss, frequency response characteristics and output of a dipole patch antenna, a pet dipole patch antenna, a spiral patch antenna, an algebraic periodic patch antenna and a conformal spiral patch antenna, as shown in FIG. The actual scale 170kV GIS mock-up was produced.

Since the external sensor is installed in a spacer of the GIS to detect a partial discharge signal generated internally, the external sensor is most affected by the spacer among various parts of the GIS. 17 is a configuration diagram of a test apparatus of an external sensor. In the figure, the sensor is installed at the mock-up GIS spacer and a partial discharge generator is installed at one end of the GIS away from the sensor.

After measuring the RL of the sensor with no voltage applied (Network Analyzer, S332B, Anritsu), a partial discharge is generated and an oscilloscope (TDS-7404, Tektronix) and spectrum analyzer ( Spectrum Analyzer, FSP7, Rohde-Schwarz) were connected to check the output and frequency response of the sensor for 5pC partial discharge signal. The partial discharge amount was checked using an IEC-60270 partial discharge meter (DDX8003, Robinson).

According to the present invention, Figures 18a to 18e is an external sensor, a network analyzer (8753D) by installing a dipole patch antenna, a pad dipole patch antenna, a spiral patch antenna, a logarithmic cycle patch antenna and a conformal spiral patch antenna in a spacer (Barrier) RL results measured in HP). The resonance between the sensor and the spacer causes a lot of resonance. The RL of such a sensor is changed by the dielectric constant and spacer size of the spacer insulator (epoxy). Therefore, in order to design an external sensor, the characteristics related to the spacer should be considered first.

As a result of FIGS. 18A to 18E, it can be seen that, in the detection frequency band (500 MHz to 1.5 GHz), a sensor equipped with a pad dipole patch antenna and a logarithmic cycle patch antenna has better RL characteristics than other sensors.

19A to 19E illustrate the results of measuring the frequency response of an external sensor with respect to a 5pC partial discharge signal by using a spectrum analyzer (FSP7, Rohde-Schwarz).

Each sensor has frequency distribution in 500MHz ~ 2.0GHz band and shows frequency response similar to that of RL. Table 1 compares the channel power of the sensors in the 500MHz to 1.5GHz band. From the results of Table 1, it can be seen that among the sensors equipped with various types of patch antennas presented in the present invention, the sensor having the RL performance and the pad dipole patch antenna and the logarithmic cycle patch antenna have higher values than the other sensors. Could.

TABLE 1

Kinds Ch Power (dBm) Remarks Dipole -36.60 Fat-dipole -40.43 Spiral -46.32 Log-periodic -39.56 Log-spiral -46.25

20A to 20E illustrate the results of measuring signals detected by each external sensor with respect to a 5pC partial discharge signal with an oscilloscope (TDS-7404, Tektronix). 20A to 20E show the waveforms measured in the time domain of each sensor and the waveforms in the frequency domain by FFT, and the power calculation value (indicated by M1 in the figure) and energy (indicated by M3 in the figure) of the measured signal. Four waveforms are simultaneously displayed.

Table 2 shows the maximum output of each sensor for the 5pC partial discharge signal. From the results in Table 2, the sensors equipped with the pet dipole patch antenna and the logarithmic cycle patch antenna produced 4 to 5 times higher output than the other sensors. This means that the RL characteristic, frequency response and maximum output of the sensor are correlated with each other.

TABLE 2

Kinds Peak Power Remarks ( ㎼) (dBm) Dipole 1.3 -28.9 FAT Dipole 5.5 -22.6 Spiral 1.9 -27.2 Log periodic 6.0 -22.2 Log spiral 1.1 -29.5

Furthermore, in the external sensor of the present invention, the flat dipole patch antenna and the pair of planar logarithmic periodic patch antennas have linear polarization characteristics with respect to an E-field propagation direction (based on the GIS direction; Z-axis direction). .

While the invention has been shown and described in connection with specific embodiments thereof, it is well known in the art that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

As described above, the external partial discharge detection sensor of the gas insulated switchgear according to the present invention is installed in the GIS spacer so as to have the best return loss in the detection frequency band of 500 MHz to 1.5 GHz, and can be applied to an actual scale GIS. By applying the patch antenna of the sensor to the external sensor, the detection frequency characteristics and the maximum output power of the sensor are measured and compared with respect to the partial discharge signal of 5pC, so that the most suitable patch antenna can be selected for the correlation and installation structure of each characteristic. It is. Moreover, correlations were established through computer simulations and experiments on the basic characteristics required to develop various types of sensors applicable to GIS.

Claims (6)

delete  In the partial discharge detection sensor including a patch antenna installed in a GIS (Gas Insulated Switchgear) spacer to sense a partial discharge UHF (Ultra High Frequency) signal generated inside the GIS, The patch antenna detects a partial discharge signal in a frequency detection band of 500 MHz to 1.5 GHz , The length of the antenna is proportional to the half wavelength (λ / 2) as a function of frequency, and the detection sensitivity characteristic is due to the omnidirectional radiation characteristic and the linear polarization characteristic with respect to the field propagation direction and the relative dielectric constant (εr) of at least one of the substrate and the insulator A Fat dipole patch antenna having the same feature of varying length and width ; Or an external partial discharge detection sensor of a gas insulated switchgear, characterized in that one of a pair of planar logarithmic periodic patch antennas periodically changed as the number of frequencies is applied to the broadband antenna element. The method of claim 2, The patch antenna has a rectangular shape of 30-50 mm in width, 100-110 mm in length, 1-2 mm in thickness, and is mounted on a substrate having a relative dielectric constant (ε _r ) of 4.0-5.0 (FR4). External partial discharge detection sensor of the gas insulated switchgear. The method of claim 2, An external partial discharge detection sensor of a gas insulated switchgear, wherein the pad dipole patch antenna has a dipole width of 15-20 mm, a length of 15-20 mm, and a gap between dipoles of 1-3 mm. The method of claim 2, Slot width of the pair of planar logarithmic patch antennas

It is 0.80-0.90, the board size is 30-50mm in width and 30-50mm in length, the thickness of the board is 1-2mm, the length (L ₀ ) inside the antenna saw blade is 10-30mm, the length of the outside of the saw blade ( L ₁ ) is 40-50mm, the relative dielectric constant ε _r of the substrate is 4.0-5.0 (FR4), the center terminal distance is 1-3mm, the external partial discharge detection sensor of the gas insulated switchgear. delete

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