JP3195862B2 - Partial discharge detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial discharge detecting device used for detecting a partial discharge generated inside a gas insulated switchgear, and more particularly to a partial discharge detecting device used for an outdoor substation having a lot of external noise. It concerns the device.

[0002]

2. Description of the Related Art In recent years, there has been a necessity of strengthening substation facilities in accordance with soaring land and an increase in power supply in urban areas. A so-called gas insulated switchgear, in which substation equipment such as a transformer is housed and arranged in a sealed container and which has a compact installation resistance per environment resistance and kV · A, has been widely used.

The gas insulated switchgear as described above has advantages such as downsizing and elimination of the exposed charged portion of the ground tank, but has difficulty in maintenance diagnosis due to high performance and increases maintenance repair work time. There is a drawback that when an abnormality occurs inside the container, the reliability is significantly reduced.

[0004] For this reason, various efforts have been made in the past to appropriately improve the design and manufacture of a gas insulated switchgear in order to improve the reliability of the entire gas insulated switchgear. As a part of this, it is necessary to check and monitor the reliability of the entire apparatus, and various studies have been made on effective means.

As one of such means, there is a partial discharge detection device used for detecting a partial discharge generated inside a gas insulated switchgear. FIG. 5 shows an example of a conventional partial discharge detection device. That is, a general closed gas switch is housed in a metal container 1, which is electrically divided by an insulating spacer 2 and connected in the longitudinal direction. In the metal container 1, a central conductor 3, which is a high-voltage charging section electrically connected to a transmission line (not shown), is provided, and is supported by the insulating spacer 2.

The metal container 1 is grounded by a ground wire (not shown). The insulating spacer 2 is provided with an electrode 4 for detection of electric power, and a stray capacitance C2 exists between the electrode 4 and the metal container 1.
2 is shown as a capacitor 5. A partial discharge detection device 7 is connected to both terminals of the capacitor 5 via signal drop lines 6a and 6b. This partial discharge detection device 7 is configured such that an amplifier circuit 9 is connected to a filter 8 for extracting a signal of a specific frequency, and further a peak detector and an integration circuit 10 are connected. A power supply 11 is connected to these devices.

[0007] The conventional partial discharge detecting device thus configured operates as described below. That is, when a high voltage is applied to the center conductor 3, the stray capacitance C1 and the capacitor 5 (stray capacitance C2) existing between the center conductor 3 and the electrode 4
Constitute a voltage divider and generate a shared voltage across capacitor 5. When a partial discharge pulse (corona pulse) is generated in the switch, a high-frequency component (signal) due to the discharge is superimposed on the shared voltage and input to the partial discharge detection device 7. In the partial discharge detection device 7, a signal of a specific frequency corresponding to the partial discharge pulse is extracted by the filter 8 and amplified by the amplifier circuit 9,
The signal is output to the outside via the peak detector and the integration circuit 10. Then, from this output signal, it is possible to detect that partial discharge has occurred inside the switch.

[0008]

However, the above-described conventional partial discharge detection device has the following problems. That is, in a gas insulated switchgear arranged in an outdoor substation as shown in FIG. 6, various noises such as broadcast waves, communication waves, and airborne coronas enter the switchgear from the transmission line 81. come. On the other hand, since the other portion is shielded by the grounded metal container, noise existing in the air does not enter the inside from the other portion.

Therefore, noise that enters the switchgear from the transmission line 81 is measured by a plurality of partial discharge detectors disposed at predetermined locations (A to E in the figure) of the gas insulated switchgear. How to remove the influence on the result has been a very important issue in providing a highly accurate partial discharge detection device.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to detect a partial discharge which is not affected by noise existing in the air and has excellent detection accuracy. It is to provide a device.

[0011]

According to a first aspect of the present invention, there is provided a gas insulated switchgear in which a high-voltage charging portion is accommodated in a grounded metal container filled with an insulating gas while being supported by an insulating spacer. A partial discharge detection device, wherein a partial discharge detection electrode is provided in a grounded metal container and the detection is performed by a high-frequency signal induced at the electrode, wherein the partial discharge detection device is provided near an air bushing. The detection frequency range of the discharge detection device is set to 500 MH, which is higher than the detection frequency range of the partial discharge detection device disposed in other places.
z or more, and the detection frequency range of the partial discharge detection device arranged at a location other than the vicinity of the air bushing is selected to be 100 MHz or less, and the partial discharge detection device is set to 4 m to 15 m. Are arranged at intervals.

[0012]

The partial discharge detection device according to the present invention is different from a partial discharge detection device provided near an air bushing into which air noise enters, and a partial discharge detection device provided at other locations. With this configuration, the detection accuracy of the partial discharge at each of the arrangement locations is excellent, and the influence of air noise can be suppressed to a minimum.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have conducted intensive studies based on various measurement data in order to solve the above-mentioned problems of the prior art, and as a result, have reached the present invention. Hereinafter, before describing embodiments of the present invention, the technical basis thereof will be described.

FIG. 2 shows the measurement results of the frequency distribution of noise in the portions A and B inside the gas insulated switchgear shown in FIG. The noise in such a grounded metal container is measured by connecting a coaxial cable to the detection electrode 4 of the insulating spacer shown in FIG. 5 and using a spectrum analyzer. In FIG. 2, the horizontal axis represents frequency, and the vertical axis represents the magnitude (spectrum magnitude) of each frequency component in dB (decibel).

Comparing the two figures, the portion A near the aerial bushing 82 has a lot of noise, and the noise exists up to a high frequency region of 600 MHz or more, but the portion B has less noise. In addition, it can be seen that there is almost no frequency component of 200 MHz or more.

FIG. 3 shows a result of measuring a signal when a partial discharge occurs in a gas in the transformer 85 shown in FIG. 6 by a similar measuring method. In addition,
The measurement was performed for each of the B, C, D, and E sections. As for the display of the figure, similarly to FIG.
The vertical axis indicates the magnitude of the spectrum in dB.

As is clear from the measurement results of FIG. 3, the signal is 1 GH near the location where the partial discharge occurs (parts B and C).
It can be seen that the high-frequency component is present up to about z, but the high-frequency component is significantly attenuated as the distance from the generation source increases (D part, E part).

This is considered to be due to the following reasons. In other words, the waveform of the partial discharge pulse having a pulse width of about 1 ns has a shape close to the original shape near the location where the partial discharge occurs, so that the frequency spectrum of the measured signal is also one.
It exists up to about GHz. On the other hand, as the partial discharge pulse propagates inside the gas insulated switchgear, the waveform of the partial discharge pulse is greatly distorted due to reciprocating reflection, demultiplexing, etc., so that the high-frequency component is greatly attenuated as shown in this measurement result. It is considered something.

Next, FIG. 4 shows the state of attenuation of the partial discharge signal in each frequency region based on the above-mentioned measurement data at the site and test data carried out in the factory. That is, the component of 600 MHz or more is greatly attenuated when it propagates about 4 to 5 m from the signal generation point, whereas the component of about 60 MHz has a relatively small attenuation and 10 m in the switchgear. It turned out that only about half attenuated even if it propagated.

From the above test results, the following has been found. (1) Of the components present inside the switchgear due to air noise,
Those with 600 MHz or higher are few. (2) The frequency component of the partial discharge pulse signal exists up to the 1 GHz region, but the component above 600 MHz attenuates within several meters from the signal generation point. (3) A frequency component of about 60 MHz propagates in the switchgear with a relatively small amount of attenuation, and the attenuation distance is about 7 to 15 m. (4) Even in the region of 100 MHz or less, there is a region where the air noise is small.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to the drawings.

In this embodiment, as shown in FIG.
In the gas insulated switchgear, a partial discharge detection device 21a having a high detection frequency is disposed in the vicinity of an air bushing portion having a plurality of lines, and other portions have relatively little signal attenuation and a low detection frequency. Partial discharge detection device 21b
Are arranged. The signals detected by these partial discharge detection devices 21a and 21b are input to a receiver 25, and subjected to pre-processing such as data conversion and conversion in a monitoring panel 22 installed at the site, and then to a control room or the like. Is transmitted to a data processing unit 23 installed in the apparatus, where abnormality determination, data display output, and the like are performed.

The partial discharge detection devices 21a, 21a
The specific configuration of b is as follows. That is, FIG.
In the partial discharge detection device 21a installed in the portion A near the middle and air bushings, a band-pass filter is used instead of the filter used in the conventional partial discharge detection device, and the detection frequency region is reduced to 500 MHz with less noise.
The above is more preferably selected in the high frequency region of 600 MHz or more. On the other hand, in FIG.
In the partial discharge detection device 21b installed at the portion from the portion to the main bus 89 (portion B to portion E), the detection frequency of the band-pass filter is set to a value less than 100 MHz where signal attenuation is small, and the air noise is reduced. Select an area with less Further, the amplification circuit connected to the band-pass filter has a wide band. Further, the partial discharge detection device having a low detection frequency range is placed at a position away from the air bushing.
They are arranged at intervals of m to 15 m.

The partial discharge detecting device according to the present embodiment having such a structure operates as described below. That is, the detection frequency range of the partial discharge detection device installed near the air bushing is set to 500 MHz or more, more preferably 600 MHz.
By selecting a high-frequency region equal to or higher than z, high-precision partial discharge detection that is not affected by air noise can be performed in a range where the partial discharge signal is not attenuated. On the other hand, by selecting the detection frequency region of the partial discharge detection device installed at a location away from the air bushing to a region of 100 MHz or less, the partial discharge signal is not similarly attenuated, and the influence of the air noise is similarly reduced. It is possible to perform highly accurate partial discharge detection that is not received.

As described above, according to the partial discharge detecting device of the present embodiment, a more accurate and sensitive partial discharge detecting device which is not affected by aerial noise can be constructed. It is possible to monitor the internal partial discharge of the gas insulated switchgear more accurately and at low cost. Further, since the accuracy of the partial discharge detection device can be greatly improved, the number of partial discharge detection devices installed in the gas insulated switchgear can be reduced.

[0027]

As described above, according to the partial discharge detection device of the present invention, the detection frequency region of the partial discharge detection device disposed near the air bushing is disposed at other locations. By selecting the frequency range higher than the detection frequency range of the partial discharge detection device, it is possible to provide a partial discharge detection device excellent in detection accuracy without being affected by noise existing in the air.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a partial discharge detection system using a partial discharge detection device according to the present invention.

FIG. 2 is a diagram showing a frequency distribution of air noise in a gas insulated switchgear;

FIG. 3 is a diagram showing a frequency distribution of an output signal when a partial discharge occurs inside the gas insulated switchgear;

FIG. 4 is a diagram showing an attenuation state of a partial discharge signal in each frequency region.

FIG. 5 is a configuration diagram showing an example of a conventional partial discharge detection device.

FIG. 6 is a side view showing a configuration of a general gas insulated switchgear and a location where a partial discharge detection device is provided.

[Description of Signs] 1 ... Metal container 2 ... Insulating spacer 3 ... Center conductor 4 ... Electricity detection electrode 5 ... Capacitor 6 ... Signal lead-in line 7 ... Partial discharge detection device 8 ... Filter 9 ... Amplification circuit 10 ... Peak detector and integration Circuit 21a: Partial discharge detection device having a high detection frequency range 21b: Partial discharge detection device having a low detection frequency range 22: Monitoring panel 23: Parent data processing unit 25: Receiver 26: Data processing unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-279877 (JP, A) JP-A-4-70573 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/12

Claims (1)

(57) [Claims] 1. A grounded metal container filled with an insulating gas,
A partial discharge detection device of a gas insulated switchgear comprising a high-voltage charging section housed in a state supported by an insulating spacer, provided with an electrode for detecting partial discharge in a grounded metal container, and a high-frequency signal induced on the electrode. In the partial discharge detection device that performs detection by using, the detection frequency range of the partial discharge detection device disposed near the air bushing is set to 500 MHz higher than the detection frequency range of the partial discharge detection device disposed in other places. The above-mentioned frequency range is selected, and the detection frequency range of the partial discharge detection device arranged at a location other than the vicinity of the air bushing is selected to be a region of 100 MHz or less.
A partial discharge detection device, which is arranged at an interval of 5 m.