JPH0357977A - Device for detecting partial discharge of gas-insulated switchgear - Google Patents

Abstract

PURPOSE:To exclude the effect of external noise and to make it possible to detect and electromagnetic wave of a required frequency band efficiently and with a high S/N ratio by providing an antenna inside a tank and by using a rectangular waveguide for an antenna element. CONSTITUTION:An antenna 8 for catching an electromagnetic wave generated at the time of a corona discharge and a conducting layer 22 made up of a copper material of about 5.4mum are formed by sticking a copper leaf or other means inside a tank (pipeline) 1, 21, while a round hole (recessed part) 23 is provided in the middle of the tank. In the hole, a rectangular waveguide 24 is provided and it is connected to an E (electric field) coupling element 25, and H (magnetic field) coupling element 26 and receivers 27 and 28 therefor. When the corona discharge is generated in the tank 1, a discharge wave is caught by the antenna 8, passed through a high-pass filter 9 and a level comparator 7 and inputted to a waveform processing circuit 5 as a start signal when the wave is a reference value or above. Meanwhile, an ultrasonic wave is detected some time later by an ultrasonic sensor 4, and therefore the degree of the corona discharge, that is, the degree of deterioration of an insulating gas, is determined on the basis of the detection.

Description

[Detailed Description of the Invention] A. INDUSTRIAL APPLICATION FIELD The present invention relates to a partial discharge detection device for detecting partial discharge in S Fe gas of a gas insulated switchgear (GIS) to determine insulation strength.

B. SUMMARY OF THE INVENTION The present invention provides an SF. In a partial discharge detection device that detects partial discharge in gas, the influence of external noise is eliminated by installing an antenna inside the tank to capture electromagnetic waves generated by corona discharge, and by using a rectangular waveguide in the antenna section. This is because it is able to accurately detect the required electromagnetic waves.

C. Conventional technology To detect partial discharge (corona) in SFll gas in GIS, it is necessary to detect high-frequency pulse current generated by partial discharge (electromagnetic coupling method) or detect ultrasonic waves (ultrasonic method). , or a combination of these.

Figure 5 shows a case where the electromagnetic coupling method and the ultrasonic method are combined, so a grounding wire 2 is connected to the tank 1, which houses a switch such as a vacuum interrupter, and a current transformer is connected to the grounding wire 2. A CT 3 is inserted to detect high-frequency pulse current (corona current) caused by corona discharge, while an ultrasonic sensor 4 is attached to the tank I to detect ultrasonic waves during discharge, and a waveform processing circuit 5 detects the ultrasonic waves generated by the discharge. I'm trying to process it.

The current transformer 3 is used as a start signal for this waveform processing circuit 5.
The output of the level comparator 7 which compares the output of the reference value setter 6 with the output (reference value) of the reference value setter 6 is used.

With such a configuration, when a corona discharge occurs in the GIS, the high frequency pulse current jc is first detected by the current transformer 3, and this is compared with a reference value by the level comparator 7. This comparison output is applied to the waveform processing circuit 5 as a start signal.

On the other hand, an ultrasonic wave is detected by the ultrasonic sensor 4 after a certain time delay (see FIG. 6), and becomes the human power of the waveform processing circuit 5.

Here, waveform processing of the ultrasonic detection signal is performed to determine whether or not there is a partial discharge, or the extent of the partial discharge. That is, detection of a high frequency pulse current generated by partial discharge is the start of the partial discharge determination process.

D. Problems to be Solved by the Invention However, in such a configuration, since the GIS tank 1 plays the role of an antenna, a noise current in flows through the tank 1 due to external noise, and this is detected by the current transformer 3. and unnecessary processing operations are performed. In other words, there is a problem in that it is easily influenced by external noise.

An object of the present invention is to provide a partial discharge detection device for a gas-insulated switchgear that can eliminate the influence of external noise as much as possible.

E. Means for Solving the Problems The present invention provides an ultrasonic sensor attached to a tank for a gas insulated switchgear in which a switch, a conductor of a live part, etc. are housed, and an ultrasonic sensor that transmits electromagnetic waves generated by corona discharge inside the tank. An antenna installed to capture the ultrasonic wave, a waveform processing circuit that performs waveform processing of the ultrasonic detection signal, and an electromagnetic wave detection signal from the antenna is compared with a reference value, and when the electromagnetic wave detection signal from the antenna is equal to or higher than the reference value, a start signal is given to the waveform processing circuit. A conductive layer made of a copper material formed on the inner surface of a tank for a gas insulated switchgear in which a switch, a live part conductor, etc. are housed, and a conductive layer formed on a part of the tank. a rectangular waveguide inserted into the recess, an E coupling part and an H coupling part attached to the rectangular waveguide, and a receiver connected to these coupling parts. Shino is characterized by:

F. When a working corona discharge occurs and electromagnetic waves and ultrasonic waves are generated, the electromagnetic waves are captured by an antenna, and the detected signal is compared with a reference value by a level comparator.

If it is less than the reference value, a start signal is given to the waveform processing circuit, and the waveform processing of the input ultrasonic detection signal is performed with a certain time delay.

In addition, when corona discharge occurs and electromagnetic waves are generated, the electromagnetic waves in the required frequency band propagate with low loss due to the presence of the conductive layer.
Transmitted into a rectangular waveguide. Then, it is detected with a high S/N ratio due to the Takagi filter effect of the waveguide.

G. EXAMPLES Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIG. 1 shows an embodiment of the present invention, where I is a tank in which a switch such as a vacuum inruptor is housed, 2 is a grounding wire, 4 is an ultrasonic sensor attached to the tank L, 5 is a waveform processing circuit that performs waveform processing of the ultrasonic detection signal, 6 is a reference value setting device, and 7 is a comparison between the set value (reference value) by this setting device 6 and human power (the subsequent electromagnetic wave detection signal), A level comparator provides the output as a start signal to the waveform processing circuit 5; 8 is an antenna provided inside the tank 1 to capture electromagnetic waves generated during corona discharge; 9 is a manual end of the level comparator 7; This is a high pass filter provided between the antennas 8.

Next, the operation will be described. When corona discharge occurs within the GIS tank I, ultrasonic waves are generated in addition to the radio waves being emitted. The radiated radio waves are captured by an antenna 8 and inputted to a level comparator 7 as an electromagnetic wave detection signal via a high-pass filter 9.

This comparator 7 compares it with a reference value, and if it is greater than or equal to the reference value, it is applied to the waveform processing circuit 5 as a comparison output or a start signal.

On the other hand, the ultrasonic wave is detected by the ultrasonic sensor 4 after a certain time delay and becomes an input to the waveform processing circuit 5.

At this time, a start signal is applied from the level comparator 7 to the waveform processing circuit 5, and waveform processing is started. This process determines the degree of corona discharge, that is, the degree of deterioration of the insulating gas.

In this case, since the antenna 8 is inside the tank 1, external radio waves are blocked by the tank 1. In addition, as shown in Fig. 2, the noise that enters the GIS from the imaginary ill through the busonong part IA, the surge impedance ZI between the live part conductor of the GIS and the tank l, the surge impedance Z between the tank l and the ground, Because the pressure is divided between the two, it becomes smaller.

As a result, the influence of external noise is significantly reduced.

3 and 4 show means for detecting radiated radio waves (electromagnetic waves) within the GIS tank 1, in which a conductive layer 2 made of copper material with a thickness of about 5.4 μm is placed on the inner surface of the GIS pipe (tank) 21.
A circular hole (recess) 23 is provided in the middle of the conduit 2l, and a rectangular waveguide 24 is inserted into it, forming a so-called electromagnetic horn. .

This rectangular waveguide 24 has an E (electric field) coupling part 25 and an H (
magnetic field, ) coupling portions 26 are provided, each connected to a receiver 2728.

Note that the reason why the thickness of the conductive layer 22 made of copper material is set to about 5.4 μm is because the skin thickness when a high frequency current of 300 MI{z flows through the surface of copper is taken into consideration. Also, GIS
The conductor of the live part is surrounded by a ground conduit, and the external noise coming in from the bushing is below several hundred MHz, so UHF noise does not appear even near the bushing.
It is decided that electromagnetic waves in the band (300 MHz to 3 C I-{ z ) or higher are to be detected, and the rectangular waveguide 24 is sized to match this.

With such a structure, among the electromagnetic waves in the frequency band up to the UHP band generated by corona discharge in the conduit (tank) 21, electromagnetic waves in the UHF band are absorbed by the presence of the conductive layer 22 made of copper material. Propagates with low loss due to rectangular waveguide 2
4. This waveguide has a ``Takagi filter effect,'' which cuts electromagnetic waves with wavelengths longer than its cutoff wavelength. Therefore, even if external noise penetrates this far, it is prevented from entering the waveguide 24 and only the electromagnetic waves to be detected are transmitted. And E coupling part 25 and 1-
1 is detected by the receivers 27 and 28 via the coupling section 26. The receivers 27 and 28 with higher outputs are selected.

H. Effects of the Invention As described above, according to the present invention, since an antenna is provided in the GIS tank to capture electromagnetic waves generated by corona discharge, the influence of outer noise can be significantly reduced. In addition, by providing four parts in a part of the tank (pipe line) and inserting a waveguide into these parts to create an antenna, by forming a conductive layer made of copper material on the inner surface of the pipe line,
It becomes possible to detect electromagnetic waves in a required frequency band efficiently and with a high S/N ratio.

[Brief explanation of drawings]

Fig. I is a configuration diagram showing an embodiment of a partial discharge detection device for a gas insulated switchgear according to the present invention, Fig. 2 is an explanatory diagram of the state of surge intrusion from an overhead line in the same embodiment, Fig. 3 and Fig. FIG. 4 is a sectional view showing means for detecting electromagnetic waves generated by corona discharge, FIG. 5 is a configuration diagram showing a conventional example, and FIG. 6 is a waveform diagram for explaining the operation of the conventional example. ■ and 2l... Tank (pipeline), 2... Ground wire, 4
Ultrasonic sensor, 5... Waveform processing circuit, 6... Reference value setter, 7... Level comparator, 8... Antenna, 9
High-pass filter, l1... Overhead line, 22... Conductive layer made of copper material, 23... Hole, 24... Rectangular waveguide, 25... E coupling part, 26... H coupling part, 27 , 2 8... Receiver. Diagram 1 of the other two people

Claims (2)

[Claims] (1) An ultrasonic sensor attached to a tank for a gas insulated switchgear that houses a switch, a conductor of a live part, etc. inside the tank, and an antenna installed inside the tank to capture electromagnetic waves generated by corona discharge; A waveform processing circuit that performs waveform processing of an ultrasonic detection signal, and a level comparator that compares the electromagnetic wave detection signal from the antenna with a reference value and provides a start signal to the waveform processing circuit when the electromagnetic wave detection signal from the antenna is equal to or greater than the reference value. A partial discharge detection device for a gas insulated switchgear, characterized in that: (2) A conductive layer made of a copper material formed on the inner surface of a tank for a gas insulated switchgear that houses a switch, a live part conductor, etc., a recess provided in a part of the tank, and a conductive layer that is inserted into the recess. A gas-insulated switchgear characterized by comprising a rectangular waveguide, an E coupling part and an H coupling part attached to the rectangular waveguide, and a receiver connected to these coupling parts. partial discharge detection device.