CN1115566C - Partial discharge detector of gas-insulated apparatus - Google Patents

Abstract

A compact antenna with a wide band and high sensitivity is used for detecting an electromagnetic wave caused by partial discharge which occurs in the interior abnormality of gas-insulated equipment. Two semicircular boards in a metal container 3 of the gas-insulated equipment are assembled on a plane to form a circular antenna receiving part 4 which is utilized to use the wide band and the high sensitivity to detect the electromagnetic wave with the partial electricity. Detected signals pass through a coaxial seal terminal 7 and a coaxial cable 8 and are measured by a measuring device 10. In addition, because the antenna receiving part of the semicircular boards is made to have a large area, the electric capacity between the antenna receiving part and an electric potential measuring part can be increased; accordingly, electric potentials can be measured with high sensitivity.

Description

Partial discharge detection device for gas insulated equipment

technical field

The present invention relates to a partial discharge detection device for gas-insulated equipment, particularly suitable for detecting the insulation generated inside a metal container from the outside of the metal container in gas-insulated equipment such as gas circuit breakers filled with insulating gas, gas-insulated switchgear, and gas-insulated busbars. An abnormality is a partial discharge signal detection device that is a partial discharge.

Background technique

As electric power equipment used in substations, there are gas-insulated switchgear, gas-insulated bus bars, gas-insulated transformers, and the like. These electrical equipment are gas-insulated equipment in which a high-voltage conductor is insulated and supported in an airtight metal container filled with insulating gas. When there are internal defects such as metal foreign objects, a high electric field will be formed locally, resulting in partial discharge. If the partial discharge that occurs is left alone, it will cause insulation breakdown, which may cause a major accident. Therefore, it is necessary to detect such a partial discharge occurring inside the metal container at an early stage and to take some kind of countermeasure. It is well known that insulation damage can be predicted in advance by detecting partial discharge signals, and attention has been paid to detecting partial discharge as a preventive protection method for gas-insulated equipment.

However, the partial discharge in SF ₆ gas is a high-voltage phenomenon in which a sharp pulse current occurs, and the electromagnetic wave generated by the partial discharge radiates into space instantaneously and propagates in the metal container. Therefore, it is possible to predict insulation abnormality by detecting this electromagnetic wave. However, since the container is an airtight container, electromagnetic waves are hardly radiated from the inside to the outside of the metal container. Therefore, a measuring device that detects the signal inside the airtight container and uses an airtight terminal to measure it from the outside has been proposed. Partial discharge detection device for gas insulated equipment for detection.

For example, known methods include, as described in Japanese Patent Application Laid-Open No. 3-56016, a loop antenna is installed in a metal container of a gas-insulated device, and the loop antenna detects electromagnetic waves radiated from partial discharges that occur, and As described in Japanese Patent Application Laid-Open No. 3-164023, a detection method is performed from the outside of a metal container using a slot antenna.

In addition, for gas-insulated equipment, a voltage detection device is also required for voltage detection in the operation voltage measurement to check whether a normal voltage is applied and the surge voltage measurement to check lightning or switching surge. As a non-contact detection method for this voltage measurement, there is known an electrostatic voltage dividing method as described in Japanese Patent Application Laid-Open No. 8-248065.

The previous partial discharge detection method for gas-insulated equipment is the method described above, but the partial discharge signal is very weak, and due to the influence of external noise, the detection sensitivity of the partial discharge signal may not meet the required accuracy. Therefore, A higher sensitivity partial discharge detection method is desired. In addition, depending on the location where the partial discharge occurs, not only the magnitude of the signal but also the output of each frequency may vary greatly. In order to calibrate the part where the partial discharge occurs, it is required to have high detection sensitivity in a very wide frequency band from 0 to several GHz.

In addition, in voltage measurement, in order to perform accurate measurement, the measurement apparatus becomes large-scale, and therefore, a method capable of simple and accurate measurement is required.

A first object of the present invention is to provide a wide-band, highly sensitive partial discharge detection device for gas-insulated equipment.

A second object of the present invention is to provide a partial discharge detection device for gas insulated equipment capable of measuring operating voltage and surge voltage.

A third object of the present invention is to provide a partial discharge detection device for gas insulated equipment with wide frequency band, high sensitivity, and capable of measuring operating voltage and surge voltage.

disclosure of invention

In order to achieve the above object, the present invention provides a partial discharge detection device for gas insulated equipment having a metal container filled with insulating gas and a high voltage conductor supported by an insulating support, comprising: A signal receiving antenna part; a coaxial cable connected to the signal receiving antenna part and electrically drawn to the outside of the above-mentioned metal container through a coaxial sealed terminal; and a measuring device connected to the coaxial cable, characterized in that: the signal receiving antenna It is formed by setting two semicircular plate-shaped conductive electrodes with a gap facing each other, representing the core wire and outer wire of the signal line of the coaxial cable and the two and a half pieces around the gap at the middle of the circle formed thereby. Any one of the circular plate-shaped conductive electrodes is connected.

A brief description of the drawings

Fig. 1 is a longitudinal sectional view showing a partial discharge detecting device for a gas-insulated device according to an embodiment of the present invention.

Fig. 2 is a longitudinal sectional view showing an example of potential measurement applied to gas insulation.

Fig. 3 is a longitudinal sectional view showing a modified example of Fig. 2 .

Fig. 4 is a longitudinal sectional view showing a modified example of Fig. 1 .

Fig. 5 is a partial longitudinal sectional view showing a modified example of Fig. 1 .

Fig. 6 is a longitudinal sectional view showing a modified example of the antenna receiving unit.

Fig. 7 is a longitudinal sectional view showing a modified example of Fig. 2 .

Fig. 8 is a longitudinal sectional view showing an example in which a reflecting plate is provided.

Best form for carrying out the invention

Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 8 . Fig. 1 is a longitudinal sectional view showing a partial discharge detection device according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view showing an example applied to gas-insulated potential measurement, and Fig. 3 is a longitudinal sectional view showing a modified example of Fig. 2 4 is a partial vertical sectional view showing a modified example of FIG. 1, FIG. 5 is a partial vertical sectional view showing a modified example of FIG. 1, and FIG. 2 is a longitudinal sectional view showing a modified example, and FIG. 8 is a longitudinal sectional view showing an example in which a reflector is provided.

The example shown in FIG. 1 shows a case where the partial discharge detecting device of this embodiment is applied to one phase of a gas-insulated bus bar well known as a gas-insulated device. A metal container 3 formed in a tubular shape has a ground potential, and in this metal container 3 , a high-voltage conductor 2 is supported by an insulating support 1 . In addition, in the metal container 3, an insulating gas such as _SF6 having excellent insulating performance is enclosed. On the case part of the metal container 3, a hand hole is provided, and in the hand hole, the antenna receiving part 4 is provided. A flange 5 for sealing is provided on the hand hole. The antenna receiving unit 4 is configured by arranging a circular plate composed of two semicircular plates in a planar shape. The two semicircular plates form conductive electrodes using copper or aluminum, which are good conductors. The antenna receiving part 4 is mounted on the antenna support stand 6 fixed to the flange 5 and provided in the hand hole. Therefore, the antenna is electrically floatingly fixed in the metal container 3 as a grounded container through an insulator. A coaxial cable 8 with a small change in impedance is provided at the center of the antenna support stand 6 . The antenna receiver 4 is connected to the coaxial cable 8 by connecting two semicircular plates to the core wire and the outer wire of the coaxial terminal near the center of the circle near the installation position. The coaxial cable 8 is connected to the coaxial cable 8 outside the metal container 3 through the coaxial sealed terminal 7 provided on the flange 5 , and further connected to the measurement device 10 through the coaxial connector.

In the partial discharge detection device for gas insulated equipment thus configured, when a partial discharge occurs in the metal container 3 , a high-frequency current pulse up to several GHz is generated, and electromagnetic waves propagate in the metal container 3 . When the propagating electromagnetic wave is received by the antenna receiving unit 4 , a voltage is induced in the antenna receiving unit 4 . The induced voltage is output to the outside of the metal container 3 through the sealed terminal 6 attached to the flange 5 , and transmitted to the measuring device 10 through the coaxial cable 8 . The antenna receiving part 4 as a detector is a structure in which two semicircular plates are combined into a circle, and is shaped to increase the area of the receiving part of the symmetrical dipole antenna, thereby increasing the capacitance between the high-voltage conductor 2 and the ground, thereby Possibility to determine the potential in gas-insulated equipment. In addition, by adopting a coaxial structure in which signals are transmitted from the antenna receiving unit, the received signals of 100 MHz or higher can be transmitted to the measurement device without attenuation, and high frequency bands of several GHz can be measured. In addition, since the space for accommodating the antenna receiving unit 4 in the metal container 3 is limited, by using such an antenna receiving unit 4, wideband signals can be received in a small space.

In addition, by using the antenna receiver 4 as a ground, the antenna itself can be used at a ground potential without using the antenna itself as a floating electrode, thereby reducing trouble even if it is installed inside a gas-insulated device.

In this way, partial discharges in a wide frequency band can be detected with high sensitivity, and not only high-precision preventive maintenance of gas-insulated equipment can be realized, but also a single antenna in the gas-insulated equipment can detect a wide range, so there is no need to install multiple antennas, so in It is also cost-effective economically.

Examples of potential measurement applied to gas-insulated equipment are shown in FIGS. 2 and 3 . At this time, the antenna receiving unit 4 is supported by a coaxial cylindrical tube without using an antenna support stand. As shown in FIG. 2 , a capacitor C1 is formed between the antenna receiving unit 4 and the high-voltage conductor 2 , and a capacitor C2 is formed between the antenna receiving unit 4 and the ground. The capacitance C1 and the capacitance C2 are values that can be measured in advance, and the potential of the static electricity divided by the capacitance can be measured by the antenna receiving unit 4 . From this determined potential, the voltage on the high-voltage conductor 2 can be determined via electrostatic partial voltage. When the potential is measured by electrostatic partial pressure, the greater the capacitance, the higher the sensitivity. In this embodiment, since the antenna receiving section 4 is configured as described above, it is suitable for a detector having a large area of the receiving section.

In addition, the example shown in FIG. 3 shows a configuration example for measuring potential with higher sensitivity. In this example, the core wire and the outside wire of the coaxial cable 8 provided outside the metal container 3 are connected, and the capacitor C3 is inserted between the core wire and the ground. By making the capacitance of the capacitor C3 much larger than that of the capacitor C2, that is, C2<<C3, high-sensitivity voltage measurement can be performed.

When the above-mentioned semicircular plate antenna is used in a gas-insulated device, it is necessary to consider the insulation degradation due to the concentration of the electric field, so the installation position becomes a problem. Since it is necessary to prevent insulation degradation due to electric field concentration under the influence of this antenna, it is installed in a low electric field part such as a particle collector, an adsorbent container, or a hand hole. At the same time, the studies shown in Fig. 4 to Fig. 6 were carried out.

In the example shown in FIG. 4 , the edge portion of the outer peripheral portion of the semicircular plate forming the antenna receiving portion 4 is rounded. By employing such a configuration, electric field concentration can be prevented without reducing reception sensitivity.

In the example shown in FIG. 5 , a shield electrode 16 made of metal as a cover is provided outside the antenna support platform 6, and the shield electrode 16 is formed to bend toward the center side, and the semicircle constituting the antenna receiving part 4 Part of the outer peripheral portion of the shaped plate is covered. Such a structure can also prevent electric field concentration.

In the example shown in FIG. 6 , the antenna receiver 4 is formed into a shape matching the cylindrical curvature of the inner surface of the metal container 3 , and installed inside the metal container 3 . In this case, it is not necessary to install in the hand hole, so, as shown in FIG. 6, a hole having the same outer diameter as the sealed terminal 7 can be formed, and the size of the flange 5 can be reduced. The antenna receiving unit 4 can install two antennas on the left and right sides of the sealed terminal 7. In this case, not only a semicircular plate but also a plate-shaped antenna in a semi-elliptical shape or a rectangle can be used. In this way, by forming the antenna so as to bend along the curvature of the inner surface of the metal container 3, it is possible to install it even if it does not fit in a hand hole as large as the antenna. In addition, insulation degradation due to electric field concentration can be prevented without reducing reception sensitivity.

In the example shown in FIG. 7 , a transmission circuit 11 equipped with a matching circuit and an amplifier is provided to transmit a signal received by the antenna receiving unit 4 in the metal container 3 in consideration of measurement at a remote location. A transmitting antenna is provided at the tip of the coaxial cable 8 connected to the transmitting circuit 11 . The measuring device 10 is set at a position away from the metal container 3 , and the receiving antenna 12 is set on the measuring device 10 through the coaxial cable 8 . The partial discharge signal detected by the antenna receiving unit 4 is impedance-matched and amplified by the transmission circuit 11 , and transmitted from the transmission antenna 13 as an electromagnetic wave. The signal transmitted by the transmitting antenna 13 is received by the receiving antenna 12 installed at a position away from the gas-insulated equipment, and is measured by the measuring device 10 . Here, by using a highly directional antenna as the receiving antenna 12, a single receiving antenna 12 can detect at which part a partial discharge has occurred in a plurality of partial discharge detection devices mounted on the gas-insulated equipment.

The example shown in FIG. 8 is an example in which the sensitivity of the antenna receiving unit 4 is made higher. A hemispherical reflector 15 having the same size as the inner diameter of the hand hole is provided between the antenna receiver 4 and the flange 5 . With such a configuration, even if the electromagnetic waves propagating in the gas-insulated device pass through without being received by the antenna receiving unit 4 , they can be reflected by the reflector 15 toward the antenna receiving unit 4 so that the passing electromagnetic waves do not leak. As a result, sensitivity can be improved by effectively collecting electromagnetic waves that cannot be received in front of the antenna receiving section 4 .

Possibility of industrial use

As described above, according to the partial discharge detection device for gas insulated equipment of the present invention, partial discharge in gas insulated equipment can be detected with high sensitivity over a wide frequency band. In addition, the potential in gas-insulated equipment can be measured using the electrostatic partial voltage with ground. In addition, it is possible to prevent the electric field concentration inside the gas insulated device due to the installation of the antenna receiving section, so that electromagnetic waves generated by partial discharge can be detected with high sensitivity in the same or wider frequency band than the symmetrical dipole antenna.

Claims (12)

1. A partial discharge detection device for a gas-insulated device having a metal container enclosing an insulating gas and a high-voltage conductor supported by an insulating support therein, comprising: a signal receiving antenna part provided in the above metal container; and The coaxial cable connected to the signal receiving antenna part is electrically drawn to the outside of the above-mentioned metal container through the coaxial sealed terminal; and the measuring device connected with the coaxial cable is characterized in that: the signal receiving antenna consists of two semicircular The plate-shaped conductive electrodes are arranged to face each other with a gap, which means that the core wire and the outer wire of the signal line of the coaxial cable are respectively connected with two semicircular plate-shaped conductive electrodes around the gap at the middle of the circle formed thereby. Any one of the electrodes is connected. 2. The partial discharge detection device for gas-insulated equipment according to claim 1, wherein the signal receiving antenna part is arranged inside the gas-insulated equipment with a low electric field intensity including an adsorbent container, a particle collector or a hand hole part. 3. The partial discharge detection device for gas insulated equipment according to claim 1 or 2, wherein a capacitor is inserted between one of the signal lines of the coaxial cable and the ground. 4. The partial discharge detection device for gas-insulated equipment according to claim 1 or 2, wherein each of the two semicircular plate-shaped conductive electrodes is formed along the edge of the metal container. The inner surface. 5. The partial discharge detection device for gas-insulated equipment according to claim 1 or 2, wherein the edge portion of each of the two semicircular plate-shaped conductive electrodes is formed into a circle on the outer peripheral side. horn. 6. The partial discharge detection device for gas-insulated equipment according to claim 1 or 2, wherein a shielding electrode is provided to cover the outer peripheral side of each of the two semicircular plate-shaped conductive electrodes . 7. The partial discharge detection device for gas-insulated equipment according to claim 1 or 2, wherein said measuring device is connected to a coaxial cable through a coaxial connector. 8. The partial discharge detection device for gas-insulated equipment according to claim 1 or 2, wherein one of the two semicircular plate-shaped conductive electrodes is grounded. 9. The partial discharge detection device for gas insulated equipment according to claim 1 or 2, wherein said signal receiving antenna part is supported by said metal container via an insulator. 10. The partial discharge detection device for gas-insulated equipment according to claim 1 or 2, further comprising: A transmitting circuit having an impedance matching circuit and an amplifier connected to the above-mentioned coaxial cable; a signal transmitting antenna connected to the coaxial cable; A signal receiving antenna for receiving electromagnetic waves transmitted from the signal transmitting antenna is connected to the measurement device. 11. The partial discharge detection device for gas insulated equipment according to claim 10, wherein a plurality of said signal transmitting antennas are provided in each part of the gas insulated equipment, and one of said signal receiving antennas is provided in said measuring device . 12. The partial discharge detection device for gas insulated equipment according to claim 1 or 2, characterized in that: between the signal receiving antenna part and the flange connected to the hand hole opening provided on the metal container, there is also a There is provided a hemispherical plate that concentrates electromagnetic waves toward the signal receiving antenna portion by reflection.

Images