JPH10234114A - Dielectric breakdown prevention device for gas insulated switchgear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the possibility of dielectric breakdowns by controlling an air exhauster or a sealing device, adjusting a gas pressure inside a tightly closed container so as to increase the dielectric breakdown voltage of a gas-installed switchgear, and increasing the difference between the operation voltage and breakdown voltage. SOLUTION: If a partial discharge occurs by a metal foreign matter inside a tightly closed container of a gas-insulated switchgear 1, a detection signal from a partial discharge detector 2 is inputted to a controller 4. If the partial discharge occurs at a gap in a gas and sealing pressure is 0.5MPa, then an electromagnetic valve 7 is opened. By the opening of the electromagnetic valve 7, an SF6 gas of the gas-insulated switchgear is discharged into an exhaust tank 5 through a gas piping 9, and the rated working pressure of 0.5MPa drops to a minimum working pressure of 0.4MPa. If the gas pressure of the gas- insulated switchgear 1 reaches the minimum working pressure, signals from a pressure sensor 3 are inputted to a control 4, the electromagnetic valve 7 is closed, the discharge of the SF6 gas is stopped, and a metallic foreign matter is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects partial discharges caused by insulation abnormality inside a gas insulated switchgear (hereinafter referred to as GIS) filled with SF6 gas, and temporarily increases the breakdown voltage of GIS. The present invention relates to a device for preventing dielectric breakdown.

[0002]

2. Description of the Related Art In GIS, substation equipment such as disconnectors, circuit breakers, and lightning arrestors are housed in a sealed container, and the insulation distance is reduced by using SF6 gas, which has excellent electrical insulation and arc extinguishing properties. This is a highly reliable power type combined switchgear with compact equipment and improved environmental resistance.

The GIS is designed to have a shape such that an equal electric field or a quasi-equal electric field is formed between the high-voltage charging section and the ground section so as to withstand a high voltage. For this reason, depending on the mixing or occurrence of metallic foreign matter such as needle-like or powder-like, the electric field is partially concentrated and an unequal electric field is formed, which lowers the insulation performance and increases the risk of dielectric breakdown. .

[0004] When an unequal electric field is formed by a metallic foreign substance, a partial discharge occurs first and a partial discharge continues to occur, unless the dielectric breakdown occurs immediately at the time of formation. In some cases leads to dielectric breakdown.

For this reason, by detecting a partial discharge, it is possible to detect an internal abnormality of the GIS before dielectric breakdown, and as an effective means for managing the GIS during operation, Japanese Patent Application Laid-Open No. H4-215074 has been proposed. Such partial discharge detectors have been studied.

[0006] When partial discharge occurs, as a method of continuing operation, gas is sealed in a GIS from a gas cylinder and the pressure is temporarily increased as in JP-A-7-23528 to suppress the occurrence of partial discharge. A way to do that has been proposed.

[0007]

However, in the partial discharge detector disclosed in Japanese Patent Application Laid-Open No. Hei 4-215074, the function of restoring the insulation performance of the GIS is displayed, although the fact that the partial discharge is detected is displayed or output as an alarm. I do not have.

In the apparatus of Japanese Patent Application Laid-Open No. Hei 7-23528, it is described that the operation can be continued by suppressing the partial discharge by increasing the pressure of the GIS.
1. In a GIS with an operating voltage of Vb, when the breakdown voltage at the time of forming an uneven electric field has the characteristics shown in FIG. 2 with respect to pressure, in a region where the breakdown voltage decreases as the pressure increases, the pressure increases from P1. Increases the risk of dielectric breakdown or may lead to dielectric breakdown.

According to the present invention, when a signal indicating that partial discharge is detected is output from the partial discharge detector, control is performed so as to temporarily increase or decrease the pressure of the GIS so as to increase the breakdown voltage. It is intended to provide a device that reduces the risk of dielectric breakdown with a simple configuration and without reducing the reliability of the device.

[0010]

In order to achieve the above object, a partial discharge detector for detecting a partial discharge in a closed container of a gas insulated switchgear filled with SF6 gas, and a gas pressure in the closed container are provided. Pressure sensor, an exhaust device for exhausting SF6 gas in the closed container, and SF6 in the closed container.
Control the gas pressure inside the sealed container so that the gas discharge device or the gas filling device is controlled by the signal from the gas discharge device and the partial discharge detector and the pressure sensor to increase the breakdown voltage of the gas insulated switchgear. In accordance with the characteristics of the breakdown voltage and the gas pressure shown in FIG. 2, the operating gas and the gas pressure of the GIS are increased by increasing the pressure in P2 and decreasing the pressure in P1 according to the characteristics shown in FIG. This is a dielectric breakdown prevention device that increases the difference from the breakdown voltage to reduce the risk of dielectric breakdown.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention. In FIG. 1, a GIS 1 includes a partial discharge detector 2 for detecting a partial discharge, a pressure sensor 3 for detecting a gas pressure in a closed container, an exhaust device 40 for exhausting SF6 gas in a closed container, and an SF6 gas in a closed container. Is provided. The exhaust device 40 includes an exhaust tank 5, an electromagnetic valve 7, and a gas pipe 9, and the sealing device 50 includes a gas cylinder 6, an electromagnetic valve 8, and a gas pipe 10. The exhaust tank 5 is set to have a capacity sufficient to reduce the pressure of the GIS 1 to the minimum operating pressure, and the gas cylinder 6 is filled with SF6 gas sufficient to increase the pressure of the GIS 1 to the maximum operating pressure. Further, the gas pipe 10 is connected to the gas pipe 9, but may be directly connected to the GIS.

Signals from the partial discharge detector 2 and the pressure sensor 3 are input to the controller 4, and the signals are used to open or close the electromagnetic valve 7 or the electromagnetic valve 8. Hereinafter, the operation will be described in detail.

FIG. 2 shows the relationship between the gas pressure and the dielectric breakdown voltage when an AC voltage is applied when an uneven electric field is formed by a gap in SF6 gas due to the incorporation of a metallic foreign matter. When the pressure of SF6 gas rises, the breakdown voltage rises once, shows a local maximum value, and then decreases. In this case, for example, a GI with a rated filling pressure of 0.5 MPa
In S, the breakdown voltage can be increased by lowering the pressure. Further, when the rated filling pressure is 0.07 MPa as in the cubicle type GIS, the breakdown voltage can be increased by increasing the pressure.

FIG. 3 shows the relationship between the gas pressure and the breakdown voltage when an unequal electric field is formed by the adhesion of metal foreign matter to the surface of an insulator in SF6 gas. The breakdown voltage decreases as the gas pressure increases. In this case, GI
The breakdown voltage can be increased by lowering the pressure irrespective of the S sealing pressure.

When a partial discharge occurs due to a metallic foreign matter in the sealed container of the GIS 1, a detection signal is input from the partial discharge detector 2 to the controller 4. At this time, since the generation pattern of the partial discharge with respect to the main circuit voltage phase has the characteristics as shown in FIG. 4, it is possible to determine whether the mixed form of the metal foreign matter is a gas gap or an insulating surface adhesion.

When the generation of the partial discharge is a gap in the gas, the controller 4 sends an open signal to the electromagnetic valve 7 at an enclosed pressure of 0.5 MPa to open the electromagnetic valve 7. When the electromagnetic valve 7 is opened, SF6 gas of the GIS 1 is discharged to the exhaust tank 5 through the gas pipe 9 and the rated working pressure is set to 0.
The pressure is reduced from 5 MPa to the minimum operating pressure of 0.4 MPa. When the sealing pressure is 0.07 MPa, an open signal is sent to the electromagnetic valve 8 to open the electromagnetic valve 8. When the electromagnetic valve 8 is opened, the SF6 gas in the gas cylinder 6 is additionally sealed into the GIS 1 through the gas pipe 10 and rises from the rated pressure of GIS 1 of 0.07 MPa to a pressure less than the pressure vessel regulation (0.2 MPa or more) of the electrical equipment technical regulations. Let it. When the partial discharge occurs on the surface of the insulator, fill pressure 0.5M
At both Pa and 0.07 MPa, the electromagnetic valve 7 is opened and the SF6 gas of the GIS 1 is discharged to the exhaust tank 5 through the gas pipe 9 to lower the pressure to the minimum operating pressure.

When the gas pressure of the GIS 1 reaches the minimum operating pressure or the maximum operating pressure, a signal is input from the pressure sensor 3 to the controller 4, and the controller 4
Alternatively, a close signal is sent to the electromagnetic valve 8 to close the electromagnetic valve 7 or the electromagnetic valve 8 to stop the release or sealing of the SF6 gas. This state is continued until the metallic foreign matter mixed in the closed container of the GIS is removed. Therefore, the operation can be stopped at an early stage, the metallic foreign matter in the closed container can be removed, and the normal state can be restored.

[0018]

According to the GIS, when a partial discharge caused by mixing of a metallic foreign substance into the main body closed container and formation of an uneven electric field due to generation is detected by a partial discharge detector, the G
By increasing or decreasing the gas pressure of the IS,
The dielectric breakdown voltage can be temporarily increased to reduce the risk of dielectric breakdown.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of a dielectric breakdown prevention device of the present invention.

FIG. 2 is a diagram showing an example of the relationship between gas pressure and dielectric breakdown voltage when a foreign substance is mixed and an uneven electric field is formed by a gap in gas in a gas insulated switchgear.

FIG. 3 is a diagram showing an example of the relationship between gas pressure and dielectric breakdown voltage when a foreign substance is mixed and an uneven electric field is formed due to adhesion to the surface of an insulator in a gas insulated switchgear.

FIG. 4 is a diagram showing an example of a generation pattern with respect to a main circuit voltage phase of a partial discharge when a foreign substance is mixed and a foreign substance adheres on a gap in a gas and on an insulator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas-insulated switchgear 2 Partial discharge detector 3 Pressure sensor 4 Controller 5 Exhaust tank 6 Gas cylinder 7 Solenoid valve 8 Solenoid valve 9 Gas piping 10 Gas piping 40 Exhaust device 50 Encapsulation device

Claims (1)

[Claims] 1. A partial discharge detector for detecting a partial discharge in a sealed container of a gas insulated switchgear filled with SF6 gas,
A pressure sensor for detecting the gas pressure in the closed container, an exhaust device for exhausting SF6 gas in the closed container, a sealing device for filling SF6 gas in the closed container, and a signal from the partial discharge detector and the pressure sensor A device for preventing breakdown of a gas-insulated switchgear, comprising: a controller for controlling an exhaust device or a sealing device and adjusting a gas pressure in a closed vessel so as to increase a breakdown voltage of the gas-insulated gas-insulated switchgear.