JP4732192B2 - GIS partial discharge detection sensor and insulation abnormality monitoring system using the same - Google Patents

Description

  The present invention relates to a partial discharge detection sensor for detecting an electrical signal of a partial discharge generated by an insulation abnormality of a gas insulated switchgear (hereinafter referred to as GIS) and an insulation abnormality monitoring system using the same.

The conventional partial discharge detection device for GIS leaks from the spacer and the bushing to the outside of the metal container due to the partial discharge generated in the metal container in which the insulating gas is sealed and the high voltage conductor is supported by the spacer. Conductive electromagnetic wave is provided with a dipole antenna made of a linear or plate-like conductive material along the spacer surface outside the metal container, and is electrically insulated from the antenna receiver outside the dipole antenna. A cover is attached (see, for example, Patent Document 1).
Further, the partial discharge signal is detected by installing an electrode at a position where the spacer is sandwiched between the flanges of the metal container and diverting the discharge current, and measuring the voltage generated in the detector connected between the electrodes (for example, Patent Document 2).

JP 2000-162263 A Japanese Patent Laid-Open No. 10-19969

However, in such a partial discharge detection device of GIS, since the dipole antenna resonates with respect to a frequency at which a half wavelength becomes the antenna length, the sensitivity is improved. For example, in the frequency region below 150 MHz, the antenna length However, there is a problem that it is not practical because one meter or more is required.
In the method of detecting a partial discharge signal by installing an electrode at a position where a spacer is sandwiched between flanges of a metal container and diverting a discharge current, and measuring a voltage generated in a detector connected between the electrodes, For high-frequency current exceeding 1 GHz, which is a characteristic band of the partial discharge signal, the impedance of the spacer is lowered, and the shunt component flowing to the detector side of the partial discharge current is reduced, so that the detection sensitivity is lowered. is there.

  An object of the present invention is to provide a partial discharge detection sensor for GIS that detects with high sensitivity components from low frequency to high frequency of electromagnetic waves generated by partial discharge, and an insulation abnormality monitoring system using the same.

The partial discharge detection sensor for GIS according to the present invention has a partial discharge generated in a metal container that is composed of a plurality of tanks that are integrated through insulating spacers while accommodating a high voltage portion on a central axis. In the partial discharge detection sensor for GIS to be detected, the first electric wire whose tip is electrostatically coupled to the outer peripheral end face of the flange of one of the tanks holding the spacer and the flange of the other tank holding the spacer A first electric wire is a core wire of the coaxial cable, the second electric wire is an outer conductor of the coaxial cable, and the coaxial cable is arranged parallel to the central axis, the potential difference between the flange of the flange and the other tank of said one tank being induced by electromagnetic waves generated along with the partial discharge Detects the induced by electromagnetic waves for detecting a partial discharge by receiving the electromagnetic waves leaking from the spacer Ri.

  The effect of the partial discharge detection sensor for GIS according to the present invention is that the potential difference generated on the flanges on both sides of the spacer by the partial discharge is induced with high sensitivity, and at the same time, the electromagnetic wave radiated from the spacer is detected with high sensitivity using resonance. Can do. Furthermore, since the low frequency noise is cut by electrostatic coupling between the first electric wire and the second electric wire and the tank, it is possible to provide a partial discharge sensor for GIS having a good SN ratio and high sensitivity. .

The partial discharge sensor for GIS according to the present invention detects an electromagnetic wave leaking from a spacer sandwiched between a metal container for detecting an electric field change of a metal container of GIS and an electrode pair electrostatically coupled to the flange of the metal container. And an antenna section. In other words, the electric field change generated on the wall surface of the metal container when the electromagnetic wave generated by the partial discharge propagates in the metal container that can be regarded as a waveguide is arranged so as to face the metal container through the dielectric member. Detected by a pair of electrodes. On the other hand, an electromagnetic wave propagating through the metal container and leaking from the spacer which is an opening of the impedance discontinuity surface is detected by a monopole antenna disposed on the outer peripheral end surface of the spacer. At this time, the sensitivity with respect to the frequency band of 10 MHz to several hundred MHz is favorable for the electrode pair electrostatically coupled to the metal container, and the sensitivity to the frequency band of several hundred MHz to several GHz is good for the antenna unit. The partial discharge sensor for GIS according to the present invention has good sensitivity in the electromagnetic wave band extending from 10 MHz to several GHz as a result of having both sensitivities.
Hereinafter, embodiments of the present invention will be specifically described.

Embodiment 1 FIG.
FIG. 1 is a view showing a state where a GIS partial discharge sensor according to Embodiment 1 of the present invention is arranged in a metal container. FIG. 2 is a top view of the GIS partial discharge sensor according to the first embodiment. FIG. 3 is a block diagram of an insulation abnormality monitoring system according to the present invention. 1 is a cross-sectional view taken along a line AA in FIG.
The GIS 1 to which the GIS partial discharge sensor according to Embodiment 1 of the present invention is applied is a general one as shown in FIGS. 1 and 2, and is a steel metal container 2 that is grounded. In order to ensure insulation between a high voltage part (not shown) disposed in the metal container 2 and the high voltage part and the metal container 2, a spacer 3 for supporting or serving as both a support and a partition is provided.

The metal container 2 includes a plurality of cylindrical tanks 4a and 4b, and flanges 5a and 5b are provided at both ends of the tanks 4a and 4b. The flanges 5a and 5b have bolt holes 8 through which the bolts 7 penetrate at equal intervals.
Moreover, the high voltage part is arrange | positioned on the central axis of tank 4a, 4b.
The spacer 3 supports the high voltage portion, and the outer peripheral edge portion 9 is sandwiched between the flanges 5a and 5b. When the spacer 3 is sandwiched between the flanges 5a and 5b, the bolt holes of the flanges 5a and 5b. A bolt hole 10 is opened at a position overlapping 8.
Then, the bolts 7 and nuts 11 passing through the flanges 5 a and 5 b and the spacer 3 are tightened and fixed.
By tightening the flanges 5a and 5b through the spacer 3 in this way, the inside of the metal container 2 is hermetically sealed, and an insulating gas such as sulfur hexafluoride gas (SF ₆ ) is enclosed therein.

  As shown in FIG. 3, the insulation abnormality monitoring system according to the present invention has a high-frequency electric field strength induced in the metal container 2 by electromagnetic waves accompanying partial discharge generated in the metal container 2 and a gap between the tanks 4 a and 4 b. The GIS partial discharge sensor 13 that detects the intensity of electromagnetic waves leaking from the GIS, the electro-optic converter 14 that converts the electrical signal of the GIS partial discharge sensor 13 into an optical signal, and the electro-optic converter 14 through the optical fiber cable 15 Status monitoring is performed based on the intensity, frequency, frequency characteristics, and histogram of partial discharge obtained from the transmitted optical signal, and it is determined that an insulation abnormality has occurred when these monitored items show the specified characteristics. An insulation abnormality monitoring device 16 is provided.

Next, the GIS partial discharge sensor 13 disposed in the GIS 1 will be described.
As shown in FIGS. 1 and 2, the GIS partial discharge sensor 13 includes a core wire 21 as a first electric wire, an insulator 22, an outer conductor 23 as a second electric wire, and an insulation coating 24. And a dielectric cable 30a, 30b disposed between the outer peripheral end face 27 of the flanges 5a, 5b and the exposed core wire 21 and the exposed outer conductor 23, respectively. The coaxial cable 25 has the longest core wire 21 and is sequentially processed in the order of an insulator 22, an outer conductor 23, and an insulating coating 24.
The coaxial cable 20 is parallel to the central axis of the metal container 2 and is disposed adjacent to the outer surfaces of the tanks 4a and 4b.
The exposed core wire 21 and the exposed outer conductor 23 are fixed to the outer peripheral end surfaces 27 of the flanges 5a and 5b via dielectric plates 30a and 30b, respectively.

Next, the state of propagation of electromagnetic waves when a partial discharge occurs in the high voltage portions in the tanks 4a and 4b will be described.
In the tanks 4a and 4b, for example, when a foreign matter adheres to a high voltage part or a crack of a solid insulator occurs and a problem in insulation occurs, a partial discharge is generated at that part and an electromagnetic wave is emitted. Since this partial discharge is a very high-speed phenomenon, the radiated electromagnetic wave is a broadband signal having a frequency extending to a band exceeding 1 GHz.
Since the tanks 4a and 4b function as waveguides with respect to the electromagnetic waves, the electromagnetic waves generate many modes while resonating in the tanks 4a and 4b, and propagate to a distant place. At this time, since the impedance changes greatly between the flanges 5a and 5b holding the spacer 3 in the middle of propagation of the electromagnetic wave, the outer circumference length of the flanges 5a and 5b, the bolt 7 for fixing the flanges 5a and 5b and the spacer 3 A high frequency electric field having a frequency determined by the pitch of the spacer 3 and the thickness of the spacer 3 is generated in the central axis direction of the metal container 2 from one flange 5a toward the other flange 5b at the spacer 3 portion, and electromagnetic waves are radiated.

Next, the principle of detecting a high-frequency electric field by the GIS partial discharge sensor 13 will be described.
Since the core wire 21 and the outer conductor 23 of the coaxial cable 25 are electrostatically coupled to the tanks 4a and 4b via the dielectric plates 30a and 30b, the potential fluctuations of the tanks 4a and 4b are caused by the core wire 21 and the outer conductor 23. Be guided to. In this way, a high-frequency electric field due to partial discharge is induced in the coaxial cable 25.

  Since the coaxial cable 25 is an antenna having a structure in which the core wire 21 protrudes from the outer conductor 23 in the same manner as the basic structure of a so-called monopole antenna, the coaxial cable 25 receives electromagnetic waves whose quarter wavelength is the length of the core wire 21. . Since the length of the core wire 21 referred to here is the length of the core wire 21 protruding from the outer conductor 23, it is the sum of the thickness of the flange 5b and the thickness of the spacer 3, but the coaxial cable 25 is close to the flange 5b. In this configuration, the thickness of the spacer 3 is substantially the length that functions as an antenna.

At this time, the core wire 21 and the outer conductor 23 electrostatically coupled to the metal container 2 have good sensitivity to the frequency band from 10 MHz to several hundreds MHz, and the antenna section from which the core wire 21 protrudes has good sensitivity to the frequency band from several hundred MHz to several GHz. Since electromagnetic waves in two frequency bands are detected in this manner, a high frequency electric field in a wide frequency band due to partial discharge can be detected.
On the other hand, noise components distributed mainly in a low frequency band are attenuated by the dielectric plates 30a and 30b disposed between the flanges 5a and 5b and the core wire 21 and the outer conductor 23.

Next, a signal detected by the GIS partial discharge sensor 13 according to the first embodiment when a partial discharge simulated pulse is injected into the metal container 2 of the GIS 1 will be described. As a comparative example, a signal detected by a dipole antenna disclosed in Patent Document 1 will also be described. FIG. 4 shows detected signals that change with the passage of time by the dipole antenna and the GIS partial discharge sensor 13 according to the first embodiment. FIG. 5 shows the frequency spectrum of the signal detected by the GIS partial discharge sensor 13 according to the first embodiment shown in FIG. FIG. 6 shows the frequency spectrum of the signal detected by the dipole antenna shown in FIG.
As can be seen from FIGS. 4 to 6, the GIS partial discharge sensor 13 according to the first embodiment has a higher signal strength compared to the dipole antenna, and the signal strength detected in a wide frequency range. Is big.

  By using the GIS partial discharge sensor 13 according to the first embodiment, a weak partial discharge electromagnetic wave can be detected with high sensitivity over a wide frequency range, and a low-frequency noise component is attenuated. Partial discharge detection with an excellent SN ratio is possible.

  In addition, such an insulation abnormality monitoring system using the GIS partial discharge detection sensor 13 connects the GIS partial discharge sensor 13 and the insulation abnormality monitoring device 16 with an optical fiber cable 15, so that the GIS 1 can be opened and closed. The accompanying surge voltage or the like can be prevented from shifting to the insulation abnormality monitoring device 16, and a highly reliable insulation abnormality monitoring system can be realized.

Embodiment 2. FIG.
FIG. 7 is a view showing a state where the GIS partial discharge sensor according to the second embodiment of the present invention is arranged in a metal container. FIG. 8 is a view of the GIS partial discharge sensor according to the second embodiment as viewed from above. 7 is a cross-sectional view taken along the line BB of FIG.
The GIS partial discharge sensor 13B according to the second embodiment of the present invention has an electrode 35a that increases and equalizes the capacitance between the tanks 4a and 4b of the GIS partial discharge sensor 13 according to the first embodiment. , 35b are added, and the rest is the same, and the same parts are denoted by the same reference numerals and the description thereof is omitted.
As shown in FIGS. 7 and 8, the electrodes 35a and 35b according to the second embodiment are exposed to the first electrode 35b installed on the outer peripheral end surface 27 of the flange 5b where the exposed core wire 21 is disposed. It is comprised from the 2nd electrode 35a installed on the outer peripheral end surface 27 of the flange 5a in which the outer skin conductor 23 currently arranged is arrange | positioned.
The first electrode 35b and the second electrode 35a are quadrangular plates having sides equal to the lengths of the exposed core wire 21 and the outer conductor 23, respectively.

In this way, the first electrode 35b is connected to the core wire 21, and the first electrode 35b is disposed so as to face the outer peripheral end surface of the flange 5b via the dielectric plate 30b. Therefore, the core wire 21 and the tank 4b Is determined by the thickness of the dielectric plate 30b, the dielectric constant of the dielectric plate 30b, and the area of the first electrode 35b, so that only the core wire 21 is the dielectric plate 30b as in the first embodiment. As compared with the electrostatic capacity determined by facing the tank 4b via, the value can be easily controlled.
Further, the second electrode 35a is connected to the outer conductor 23, and the second electrode 35a is disposed so as to face the outer peripheral end surface 27 of the flange 5a via the dielectric plate 30a. 4a is determined by the thickness of the dielectric plate 30a, the dielectric constant of the dielectric plate 30a, and the area of the second electrode 35a, so that only the outer conductor 23 is dielectric as in the first embodiment. The value can be easily controlled as compared with the capacitance determined by facing the tank 4a through the body plate 30a.

Such a partial discharge sensor 13B for GIS is induced between the flanges 5a and 5b because the core wire 21 and the outer conductor 23 and the tanks 4a and 4b are electrostatically coupled by a precisely controlled capacitance. Variation in sensitivity for detecting the electric field strength between models is reduced.
Further, since it is opposed to the outer peripheral end surfaces of the flanges 5a and 5b in a plane, the predetermined capacitance is not necessarily required even if the first electrode 35b and the second electrode 35a are not in close contact with the dielectric plates 30a and 30b. Is obtained.

  A predetermined capacitance can be obtained by spatially separating the first electrode 35b and the second electrode 35a from the outer peripheral end surfaces 27 of the flanges 5a and 5b by a predetermined distance, and therefore the dielectric plates 30a and 30b. May be omitted. If the dielectric plates 30a and 30b are omitted in this way, for example, when applied to a portable partial discharge detector, the adhesion between the GIS partial discharge sensor 13B and the outer peripheral end surfaces 27 of the flanges 5a and 5b becomes nervous. Therefore, it is possible to easily detect the partial discharge with high sensitivity.

Embodiment 3 FIG.
The partial discharge sensor for GIS according to the third embodiment is a case where the partial discharge sensor for GIS according to the first embodiment is arranged so as to face the outer peripheral end face 27 of the flanges 5a and 5b apart from the bolt 7. Since the GIS partial discharge sensor 13 itself is the same, the same reference numerals are given to the same parts and the description thereof is omitted.
The flanges 5a and 5b and the bolts 7 sandwiching the spacer 3 function like a slot antenna, and the electric field intensity on the outer peripheral end face of the spacer 3 is 1 / n (n is a positive integer) that ½ wavelength is a bolt pitch. In the case of the electromagnetic wave of), the bolt 7 portion indicates a node, and several antinodes are indicated between the bolts 7. Therefore, if the GIS partial discharge sensor 13 is arranged in the middle while avoiding the bolt 7 which is a node, it can be detected with high sensitivity. For example, when the bolt pitch is ½ wavelength of the electromagnetic wave to be detected, the middle of the bolt 7 has the strongest electric field strength. Therefore, the GIS partial discharge sensor 13 can be detected with the highest sensitivity by arranging it at that position. .
When the impedance of the slot antenna formed by the flanges 5a and 5b and the bolt 7 does not match the characteristic impedance of the coaxial cable 25, the position where the partial discharge sensor 13 for GIS is arranged is most sensitive by simulation. Sensitivity may be higher when the position obtained as good is slightly shifted.
In this way, partial discharge can be detected with high sensitivity by avoiding the top of the bolt 7 as a position where the GIS partial discharge sensor 13 is disposed.

Embodiment 4 FIG.
FIG. 9 is a diagram showing a state in which the GIS partial discharge sensor according to the fourth embodiment of the present invention is arranged in a metal container.
The GIS partial discharge sensor 13D according to the fourth embodiment differs in that a twisted pair cable 37 is used instead of the coaxial cable 25 of the GIS partial discharge sensor 13B according to the second embodiment. Since it is the same, the same code | symbol is attached | subjected to the same part and description is abbreviate | omitted.
The twisted pair cable 37 according to the fourth embodiment includes a first conductor 38a as a first electric wire connected to the first electrode 35b and a second electric wire as a second electric wire connected to the second electrode 35a. The conductor 38b is twisted.

Such a GIS partial discharge sensor 13D can detect an electromagnetic wave due to partial discharge with high sensitivity in the same manner as the GIS partial discharge sensor 13B according to the second embodiment.
Further, since the twisted pair cable 37 is also excellent as a high-frequency transmission line, it is also possible to transmit a signal directly to the insulation abnormality monitoring device 16 efficiently.
In addition, as shown in FIG. 10 instead of the twisted pair cable 37, even if the balanced feeder line 39 is used, the electromagnetic waves can be similarly detected by partial discharge.

It is the figure which showed a mode that the partial discharge sensor for GIS concerning Embodiment 1 of this invention was arrange | positioned in the metal container. It is the figure which looked at the partial discharge sensor for GIS concerning Embodiment 1 from upper direction. It is a block diagram of the insulation abnormality monitoring system concerning this invention. The detected signal which changes with progress of time by the dipole antenna and the partial discharge sensor for GIS concerning Embodiment 1 is shown. The frequency spectrum of the signal detected by the partial discharge sensor for GIS concerning Embodiment 1 shown in FIG. 4 is shown. The frequency spectrum of the signal detected by the dipole antenna shown in FIG. 4 is shown. It is the figure which showed a mode that the partial discharge sensor for GIS concerning Embodiment 2 of this invention was arrange | positioned in the metal container. It is the figure which looked at the partial discharge sensor for GIS concerning Embodiment 2 from upper direction. It is the figure which showed a mode that the partial discharge sensor for GIS concerning Embodiment 4 of this invention was arrange | positioned in the metal container. It is the figure which looked at the other partial discharge sensor for GIS concerning Embodiment 4 of this invention from the upper direction.

Explanation of symbols

  1 Gas Insulated Switchgear (GIS), 2 Metal Container, 3 Spacer, 4a, 4b Tank, 5a, 5b Flange, 7 Bolt, 8, 10 Bolt Hole, 9 (Spacer) Outer Perimeter, 11 Nut, 13, 13B , 13D GIS partial discharge sensor, 14 electro-optic converter, 15 optical fiber cable, 16 insulation abnormality monitoring device, 20 coaxial cable, 21 core wire, 22 insulator, 23 outer conductor, 24 insulation coating, 25 coaxial cable, 27 ( Peripheral end face of flange), 30a, 30b dielectric plate, 35a outer conductor electrode, 35b core wire electrode, 37 twisted pair cable, 38a, 38b conductor, 39 balanced feeder wire.

Claims (4)

In a partial discharge detection sensor for GIS that detects a partial discharge generated in a metal container configured of a plurality of tanks that are integrated via insulating spacers while accommodating a high voltage portion on a central axis,
The first electric wire whose tip is electrostatically coupled to the outer peripheral end face of the flange of one of the tanks holding the spacer and the outer end of the flange of the other tank holding the spacer are electrostatically coupled to the outer peripheral end face of the other tank. And a second electric wire
The first electric wire is a core wire of the coaxial cable, the second electric wire is an outer conductor of the coaxial cable, and the coaxial cable is arranged in parallel to the central axis;
Detecting the electromagnetic wave induced by the potential difference between the flange of the one tank and the flange of the other tank induced by the electromagnetic wave generated by the partial discharge, and receiving the electromagnetic wave leaking from the spacer A partial discharge detection sensor for GIS, which detects partial discharge using A first electrode connected to a tip of the first electric wire and electrostatically coupled to a flange of the one tank;
A second electrode connected to the tip of the second electric wire and electrostatically coupled to the flange of the other tank;
The partial discharge detection sensor for GIS according to claim 1, comprising: The tip of the first wire and the tip of the second wire are not centered on a plurality of bolts that fasten the flange of the one tank and the flange of the other tank with the spacer interposed therebetween. GIS partial discharge detection sensor according to claim 1 or 2, characterized in that located on the normal line from the axis. An insulation abnormality monitoring system using the partial discharge detection sensor for GIS according to any one of claims 1 to 3 .

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