JPH0894675A - Zero-phase current detector for gas insulation switch device - Google Patents

Abstract

PURPOSE: To provide a zero-phase current detection device for a gas insulation- opening/closing apparatus which can directly detect a zero-phase current without being influenced by an external magnetic field. CONSTITUTION: Flanges 11a, 12a of containers 11, 12 containing devices constituting an opening/closing circuit are connected each other via an insulation spacer 13. An optical fiber 22 of a plurality of the number of turns is set in the flange 12a. A fiber-optic current transformer is constituted of the optical fiber 22 to detect a zero-phase current flowing in a main circuit. conductor in the containers 11, 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zero phase current detecting device for detecting a zero phase current flowing through a main circuit conductor of a gas insulated switchgear.

[0002]

2. Description of the Related Art A gas-insulated switchgear installed in an electric substation or the like has a plurality of metal containers, which collectively accommodate the three-phase components of a switch circuit, butted together with flanges of an insulating spacer. , The butted flange and the insulating spacer are fastened with bolts, and SF _{6 is} placed in each metal container.
It has a structure in which gas is sealed at a predetermined pressure.

When a ground fault occurs in an electric station such as a substation, it is necessary to immediately detect it and take necessary measures. Therefore, in gas-insulated switchgear installed in substations, etc., a zero-phase current detector that detects the zero-phase current flowing through the main circuit conductor must be installed to detect the zero-phase current flowing through the main circuit conductor. Has been used to detect the occurrence of a ground fault.

FIG. 6A shows the structure of a zero-phase current detector used in a conventional gas-insulated switchgear.
In the figure, 1 is a metal container of the gas insulated switchgear,
Reference numerals 2u to 2w are three-phase main circuit conductors housed in the container 1 and supported by insulating spacers (not shown). Container 1
The optical current transformers 3u to 3w are attached to the outer peripheral surface of the optical waveguides at positions close to the conductors 2u to 2w, and the outputs of these optical current transformers are input to a detector (not shown). A detector (not shown) vector-adds the outputs of the optical current transformers 3u to 3w to detect a zero-phase current.

In FIG. 6A, when the three-phase currents are in equilibrium, the optical magnetic field sensors 3u to 3w are three-phase conductors 2u to 2w as shown by the solid lines in FIG. 6B.
In order to detect the magnetic field generated from the main circuit currents Iu to Iw flowing through, the vector addition of the outputs of these optical magnetic field sensors results in zero. On the other hand, for example, if a ground fault occurs between the U-phase conductor 2u and the container 1, the U-phase current disappears, and the outputs of the optical magnetic field sensors 3u to 3w are as shown in FIG.
As indicated by a broken line in (B), the detected value of the V-phase current Iv and the detected value of the W-phase current Iw are vector-added, and the zero-phase component is detected.

FIG. 7A shows another example of the structure of a zero-phase current detecting device used in a conventional gas-insulated switchgear. In this example, three-phase main circuit conductors 2u to 2w are used. Winding current transformers CTu to CTw are attached to the respective winding current transformers, and the outputs of these current transformers are input to a detector (not shown). FIG. 7B is a vector diagram similar to FIG. 6B, and in this example, the zero phase component can be detected as in the case of FIG.

[0007]

In the device shown in FIG. 6A, the three optical magnetic field sensors 3u to 3w are affected by the external magnetic field in addition to the magnetic field generated from the main circuit current. In consideration of the above, it is necessary to calculate the output of the optical magnetic field sensor to obtain the zero-phase component, and there is a problem that the calculation process becomes complicated.

Further, the apparatus shown in FIG. 7 (A) has a problem that it cannot be applied to an existing gas insulating apparatus because it is necessary to mount a current transformer in the container 1 of the gas insulating switchgear.

An object of the present invention is to provide a zero-phase current detecting device for a gas-insulated switchgear capable of detecting a zero-phase current without performing complicated arithmetic processing in consideration of the influence of an external magnetic field. .

[0010]

SUMMARY OF THE INVENTION The present invention provides a switching circuit including a switching circuit.
It is arranged in the metal container of the gas insulated switchgear in which the flanges of a plurality of metal containers that collectively house the components of the phase are butted against each other via insulating spacers, and the butted flanges and the insulating spacers are fastened with bolts. The present invention also relates to a zero-phase current detecting device for detecting a zero-phase current flowing through a three-phase main circuit conductor.

In the present invention, an optical fiber wound around a three-phase main circuit conductor around a plurality of turns is provided inside a flange of a metal container, and the optical fiber for zero-phase current detection is changed by the plurality of turns of the optical fiber. Configure a sink. To provide multiple turns of optical fiber in the flange, provide a groove on the flange to the side of the insulating spacer,
The optical fiber may be housed in the groove. In this case, the groove for accommodating the optical fiber is preferably provided on the outer peripheral side of the O-ring that seals between the insulating spacer and the flange so as not to affect the airtightness of the container. Further, the groove for accommodating the optical fiber is preferably provided on the inner peripheral side of the bolt so as not to detect the magnetic field generated from the ground fault current flowing through the bolt for fastening the flange and the insulating spacer. That is, it is preferable that the groove that accommodates the optical fiber is provided between the O-ring that seals between the insulating spacer and the flange and the bolt that fastens the flange and the insulating spacer.

The above-mentioned optical fiber current transformer utilizes an effect (Faraday effect) in which the polarization direction is rotated by the influence of the magnetic field generated by the electric current when the linearly polarized light travels in the optical fiber. Then, one end of the optical fiber is connected to the light source via the polarizer, and the other end is connected to the light receiver via the analyzer.

In the above structure, the optical fiber is provided in the flange of the container. However, the optical fiber is wound around the outer periphery of the flange of the metal container or the outer periphery of the insulating spacer by a plurality of turns, and the optical fiber of the plurality of turns is used to detect a zero-phase current. You may make it comprise a current transformer. In this case, when the short-circuit bar that connects the adjacent flanges is provided, the optical fiber is wound inside the short-circuit bar. Further, in this case, it is necessary to insulate each bolt from each flange in order to prevent a ground fault current from flowing through the bolt that fastens the flange and the insulating spacer.

[0014]

In the above device, the optical fiber current transformer is
Like an ordinary optical current transformer, one end of an optical fiber is connected to a light source through a polarizer and the other end is connected to a light receiver through an analyzer for use. The light generated by the light source passes through the polarizer to become linearly polarized light and enters the optical fiber. This linearly polarized light 3
Its polarization direction is rotated by an angle corresponding to the vector sum of the magnetic fields produced by the currents flowing in the main circuit conductors of the phases. Therefore, the optical output output through the analyzer is intensity-modulated by the vector sum of the magnetic fields generated by the currents flowing through the main circuit conductors. The vector addition value of the flowing current can be detected.

As described above, when the optical fiber current transformer is constructed by providing the optical fiber so as to circulate around the three-phase conductor a plurality of times, all the magnetic fields from the outside of the loop of the optical fiber are canceled and the inside of the metal container is closed. Only the magnetic field due to the current corresponding to the vector sum of the currents flowing through the main circuit conductor can be detected. Therefore, it is possible to directly detect the zero-phase current flowing in the steady state and the ground fault accident without performing a complicated calculation process in consideration of the influence of the external magnetic field.

When the optical fiber is wound around the outer circumference of the flange or the outer circumference of the insulating spacer, the mounting is easy, and it can be easily applied to an existing gas-insulated switchgear.

[0017]

1 and 2 show an embodiment of the present invention. FIG. 1 shows a longitudinal sectional view of a main portion, and FIG. 2A shows a sectional view taken along the line AA of FIG. ing. Further, FIG. 2B is a vector diagram of the current flowing through the main circuit conductor.

11 and 12 in FIGS. 1 and 2A.
Are metal containers of the gas insulated switchgear, and the containers 11 and 12 have flanges 11a and 12a at their ends. Adjacent flanges 11 of containers 11 and 12
a and 12a are butted against each other via the insulating spacer 13,
O-rings 14 and 15 are housed in grooves formed around the inner circumferences of the end surfaces of the flanges 11a and 12a, and these O-rings form a joint between the flanges 11a and 12a and the insulating spacer 13. Airtightness is maintained. A large number of stud bolts 16 penetrating the flanges 11a and 12a and the insulating spacer 13 are provided in the circumferential direction of the flange, and nuts are screwed on both ends of each bolt to form the flange 11
a and 12a and the insulating spacer 13 are fastened. A short-circuit bar 17 is provided across the flanges 11a and 12a, and the short-circuit bar is connected to the outer peripheral portion of the flanges 11a and 12a. The short-circuit bar electrically connects the containers 11 and 12 to each other.

The three-phase main circuit conductor 2 is provided in the containers 11 and 12.
0 u to 20 w are housed, and these main circuit conductors are partially connected to and supported by the through conductor 13 a provided in a state of being embedded in the insulating spacer 13. The gas-insulated switchgear is further provided with switching devices such as circuit breakers and disconnectors, and devices such as cable heads, and the respective devices are housed in predetermined containers, but these are not shown. .

In this embodiment, the flange 12a of the container 12 is
A groove 21 is provided around the end face of the insulating spacer 13 facing the insulating spacer 13 between the O-ring 15 and the bolt 16, and a plurality of turns are wound in the groove 21 so as to circulate around the conductors 20u to 20w. The rotated optical fiber 22 is accommodated. As the optical fiber 22, a fiber having a Faraday effect is used. Both ends 22a of the optical fiber 22,
22b is led out to the outside through a hole provided in the flange 12a. An optical fiber current transformer for detecting a zero-phase current is constituted by the optical fiber 22 wound a plurality of turns. The usage of this optical fiber current transformer is similar to that of a general optical current transformer using the Faraday effect. As shown in FIG. 4, one end 22a of the optical fiber 22 is connected to the light emitter 24 via the polarizer 23. The other end 22b is connected to the light receiver 26 via the analyzer 25.

When linearly polarized light is given to the optical fiber 22 from the light emitter 24 through the polarizer 23, the linearly polarized light is
In the process of traveling in the optical fiber, its polarization direction is rotated by an angle corresponding to the vector sum of the magnetic fields generated by the currents flowing through the main circuit conductors 20u to 20w due to the Faraday effect. Therefore, the optical output output through the analyzer 25 is intensity-modulated by the vector sum of the magnetic fields generated by the currents flowing through the main circuit conductors 20u to 20w, and this optical output is received by the photodetector 26 and demodulated. , The vector addition value of the current flowing through the main circuit conductors 20u to 20w can be detected. Figure 2
As shown by the solid line in (B), when the three-phase currents Iu to Iw are balanced, the vector addition value of these currents becomes zero, and the zero-phase component is not detected (zero-phase current is 0). .
On the other hand, for example, when a ground fault occurs between the U-phase conductor 20u and the container 12, the U-phase current Iu becomes zero, and thus the vector addition value Iv + Iw of the current is detected as the zero-phase component Io. It FIG. 5 shows an example of the waveform of the detection signal obtained by the optical current transformer. When there is no accident and the three-phase currents are balanced, the detection signal is zero, but at time t1 the ground fault occurs. When an accident occurs, a detection signal corresponding to the zero phase component Io is obtained.

Although the optical fiber is provided in the flange of the container in the above-mentioned embodiment, the optical fiber 22 may be provided so as to circulate around the three-phase conductor, and in the case of being provided in the flange as in the above-mentioned embodiment. Not limited to. For example,
As shown in FIG. 3, the zero-phase current detection optical fiber current transformer may be configured by winding the optical fiber 22 around the flange 12a of the container 12 for a plurality of turns. In this case, in order not to detect the ground fault current flowing through the short-circuit bar 17, the optical fiber 22 is wound inside the short-circuit bar 17 as shown.

Further, in order to prevent a ground fault current from flowing through the bolt 16, it is necessary to insulate each bolt from each flange.

In the example shown in FIG. 3, the optical fiber 2
Although 2 is wound around the outer circumference of the flange 12a, the optical fiber 22 may be wound around the outer circumference of the insulating spacer 13.

Although the preferred embodiments of the present invention have been described above, the main aspects of the invention disclosed in this specification will be described below.

(1) The flanges of a plurality of metal containers that collectively house the three-phase components of the switching circuit are butted against each other via an insulating spacer, and an O-ring is interposed between the insulating spacer and each flange. Detecting a zero-phase current flowing through a three-phase main circuit conductor arranged in the metal container of the gas-insulated switchgear formed by fastening a butted flange and an insulating spacer by bolts arranged on the outer peripheral side of the O-ring. In the zero-phase current detecting device, an optical fiber wound a plurality of turns around the three-phase main circuit conductor is provided between the bolt and the O-ring in the flange of the metal container. A zero-phase current detecting device for a gas-insulated switchgear, characterized in that an optical fiber current transformer for detecting a zero-phase current is constituted by the plurality of turns of the optical fiber.

(2) The flanges of a plurality of metal containers that collectively accommodate the three-phase components of the switching circuit are butted against each other through an insulating spacer, and an O-ring is interposed between the insulating spacer and each flange. Disposed in the metal container of the gas-insulated switchgear in which the butted flange and the insulating spacer are fastened together by bolts arranged on the outer peripheral side of the O-ring, and adjacent flanges are electrically connected by a short-circuit bar. In a zero-phase current detecting device for detecting a zero-phase current flowing through a three-phase main circuit conductor, an optical fiber is wound a plurality of times around the flange of the metal container or the outer circumference of an insulating spacer so as to be located inside the short-circuit bar. The optical fiber current transformer for detecting zero-phase current is constructed by the optical fibers of the plurality of turns, and each bolt is connected to the flap of the metal container. A zero-phase current detector for a gas-insulated switchgear, characterized by being insulated from the switch.

[0028]

As described above, according to the present invention, an optical fiber current transformer is formed by winding a plurality of turns of an optical fiber around a three-phase conductor, and the optical fiber current transformer is formed outside the optical fiber loop. Since the magnetic field due to the current corresponding to the vector addition value of the current flowing through the main circuit conductor in the metal container is detected while canceling the magnetic field from, it is possible to perform complicated calculation processing considering the influence of the external magnetic field. There is an advantage that the zero-phase current flowing through the main circuit conductor can be directly detected during steady state and during ground fault.

Particularly, according to the invention described in claim 2,
Since the optical fiber is wound around the outer circumference of the flange or the outer circumference of the insulating spacer, there is an advantage that it can be easily attached and can be easily applied to an existing gas-insulated switchgear.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a configuration of a main part of an embodiment of the present invention.

2A is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 2B is a vector diagram showing a vector of current of each phase of FIG.

FIG. 3 is a front view showing a partial cross-section of a main part of another embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of an optical current transformer used in an embodiment of the present invention.

FIG. 5 is a waveform diagram showing signals obtained from the optical current transformer when a ground fault occurs.

6A is a vertical cross-sectional view showing a configuration of a main part of a conventional example, and FIG. 6B is a vector diagram showing a current vector of each phase in FIG. 6A.

7A is a vertical cross-sectional view showing a configuration of a main part of another conventional example, and FIG. 7B is a vector diagram showing a current vector of each phase in FIG. 7A.

[Explanation of reference numerals] 11,12 Metal container 11a, 12a Flange 13 Insulating spacer 14,15 O-ring 20u to 20w Main circuit conductor 22 Optical fiber

Claims (2)

[Claims] 1. A gas insulation system in which flanges of a plurality of metal containers accommodating three-phase components of an opening / closing circuit are butted against each other via insulating spacers and the butted flanges and the insulating spacers are fastened by bolts. A zero-phase current detection device for detecting a zero-phase current flowing through a three-phase main circuit conductor arranged in the metal container of a switchgear, wherein the three-phase main circuit conductor is wound around a plurality of turns. A zero-phase current detecting device for a gas insulated switchgear, characterized in that an optical fiber is provided in the flange of the metal container, and an optical fiber current transformer for detecting a zero-phase current is constituted by the plurality of turns of the optical fiber. 2. Gas insulation, wherein flanges of a plurality of metal containers accommodating three-phase components of an opening / closing circuit are butted against each other via insulating spacers, and the butted flanges and the insulating spacers are fastened by bolts. A zero-phase current detection device for detecting a zero-phase current flowing through a three-phase main circuit conductor arranged in the metal container of a switchgear, wherein a plurality of turns of an optical fiber are wound around an outer periphery of a flange of the metal container or an outer periphery of an insulating spacer. A zero-phase current detecting device for a gas insulated switchgear, characterized in that an optical fiber current transformer for detecting a zero-phase current is constituted by the plurality of turns of the optical fiber.