JP2020197478A - Current transformer and electromagnetic induction type power generator using the same - Google Patents

Abstract

To provide a current transformer which is easily attachable to a power transmission line and can be reduced in size and weight, and an electromagnetic induction type power generator using the current transformer.SOLUTION: A current transformer 10 comprises: a magnetic core 11 attachable to an insulation-coated power transmission line 2; and a coil 15 wound around the magnetic core 11. The magnetic core 11 includes: a first core part 12 enclosing the power transmission line 2 in a substantially U shape; and a second core part 13 extending in a second direction orthogonal to a first direction being an extending direction of the power transmission line 2 and connecting one end 12c1 and the other end 12c2 of the first core part 12. The coil 15 is wound around the second core part 13. A thickness t1 of the first core part 12 in a direction orthogonal to the extending direction of the first core part 12 as seen from the first direction is thinner than a thickness t2 of the second core part 13 in a third direction orthogonal to the first and second directions.SELECTED DRAWING: Figure 2

Description

The present invention relates to a current transformer attached to a transmission line, an electromagnetic induction power generation device using the same, and a transmission line monitoring system, and more particularly to a structure of the current transformer.

There are known IoT devices that are attached to power lines to constantly monitor their condition. For example, Patent Document 1 describes a surveillance camera system using an electromagnetic induction type power supply device. This surveillance camera system is detachably provided on the transmission / distribution line, and has a power generation CT core that generates power by an electromagnetic induction method and a power conversion unit that converts AC power generated from the power generation CT core into DC power. , It is equipped with a camera module that shoots moving images and a wireless communication module that transmits the output data of the camera module to the outside.

Regarding a current transformer attached to a power transmission line, for example, Patent Document 2 describes a clamp-type current transformer that can be used by opening and closing a pair of split cores and arranging them around an existing electric wire or cable.

Special Table 2016-571261 International Publication No. 2017/146256 Pamphlet

Until now, regular inspections have been the mainstream for maintenance and management of underground transmission lines, and constant monitoring has not been carried out. However, with the increase in underground transmission lines, the need for constant monitoring is increasing.

As the current transformer used for the maintenance and management of the underground transmission line, the one using the split type magnetic core described in Patent Document 2 is generally used.

However, in such a conventional current transformer, the magnetic core is large and heavy, and it is difficult to attach it to a transmission line. In particular, underground transmission lines are laid in the cave, and in many cases, three transmission lines corresponding to three-phase alternating current are laid in a bundled state, so it is very difficult to install a large magnetic core. Have difficulty.

Therefore, an object of the present invention is to provide a current transformer that can be easily attached to a transmission line and can be made smaller and lighter, and an electromagnetic induction type power generation device and a transmission line monitoring system using the current transformer.

In order to solve the above problems, the current transformer according to the present invention includes a magnetic core that can be attached to an insulatingly coated transmission line and a coil wound around the magnetic core, and the magnetic core connects the transmission line. One end and the other end of the first core portion extending in a second direction orthogonal to the first direction which is the extension direction of the transmission line and the first core portion surrounding in a substantially U shape. The coil is wound around the second core portion, and the coil is wound around the second core portion, and the coil is wound in a direction orthogonal to the extending direction of the first core portion as viewed from the first direction. The thickness of the first core portion is smaller than the thickness of the second core portion in the first direction and the third direction orthogonal to the second direction.

According to the present invention, the magnetic core can be partially thinned. Therefore, it is possible to realize a current transformer that is compact, lightweight, and easy to attach to a transmission line.

In the present invention, the maximum width of the first core portion in the first direction viewed from the second direction is wider than the maximum width of the second core portion in the first direction viewed from the second direction. Is preferable. By making the first core portion thinner, it is possible to reduce the size and weight and facilitate the attachment to the transmission line, but the cross-sectional area of the first core portion becomes smaller, so that the power generation efficiency is lowered. However, when the maximum width of the first core portion is widened, it is possible to secure a sufficient cross-sectional area of the first core portion and prevent a decrease in power generation efficiency.

In the present invention, it is preferable that the second core portion is detachably configured with respect to the first core portion. As a result, the current transformer can be easily attached to the transmission line.

In the present invention, the magnetic permeability of the second core portion is preferably higher than the magnetic permeability of the first core portion. According to this configuration, the cross-sectional area of the second core portion can be reduced, and the size of the second core portion can be reduced. As a result, it is possible to reduce the size and weight without excessively reducing the magnetic permeability of the entire magnetic core.

In the present invention, the first core portion is preferably made of nickel, and the second core portion is preferably made of ferrite. When nickel is used as the material of the first core portion, a thin and rust-resistant first core portion can be realized. Further, when ferrite is used as the material of the second core portion, the second core portion having a higher magnetic permeability than the first core portion can be realized.

The length of the second core portion is preferably larger than the diameter of the lead wire portion of the transmission line. When the length of the second core portion is smaller than the diameter of the lead wire portion of the transmission line, the power generation efficiency of the current transformer is significantly reduced. However, when the length of the second core portion is smaller than the diameter of the lead wire portion of the transmission line, such a decrease in power generation efficiency can be prevented.

In the present invention, it is preferable that the first core portion has elasticity. Further, it is preferable that the inner diameter area of the first core portion changes according to the thickness of the transmission line. As a result, the current transformer can be reliably attached to the transmission line, and the versatility of the current transformer for various transmission lines can be enhanced.

It is preferable that the current transformer according to the present invention further includes a capacitor connected to the coil, and the coil and the capacitor form a resonance circuit. According to this configuration, the power generation of the current transformer can be increased.

Further, the electromagnetic induction type power generation device according to the present invention is characterized by including a current transformer having the above-described characteristics of the present invention and a power supply circuit connected to the current transformer. According to the present invention, it is possible to provide an electromagnetic induction type power generation device provided with a small and lightweight current transformer that can be easily attached to a transmission line.

Furthermore, the transmission line monitoring system according to the present invention includes the above-mentioned electromagnetic induction power generation device according to the present invention, an IoT device that receives power from the electromagnetic induction power generation device and performs a monitoring operation of the transmission line, and the above. It is characterized by including a data communication unit that transmits monitoring data acquired by the IoT device by wireless communication or wired communication. According to the present invention, it is possible to provide a transmission line monitoring system that can be easily attached to a transmission line and can suppress an excessive power supply to an IoT device.

According to the present invention, it is possible to provide a current transformer that can be easily attached to a transmission line and can be made smaller and lighter, and an electromagnetic induction type power generation device and a transmission line monitoring system using the current transformer.

FIG. 1 is a diagram schematically showing a configuration of a transmission line monitoring system according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the current transformer 10 according to the first embodiment of the present invention. FIG. 3 is a plan view showing the configuration of the current transformer 10. FIG. 4 is a diagram showing an example of a method of attaching the current transformer 10 to the transmission line 2. FIG. 5 is a schematic view showing a state in which one current transformer 10 is attached to each of three bundles of power transmission lines. FIG. 6 is a cross-sectional view showing the configuration of the current transformer 10 according to the second embodiment of the present invention. 7 (a) and 7 (b) are schematic cross-sectional views showing the configuration of the current transformer 10 according to the third embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing a configuration of a transmission line monitoring system according to an embodiment of the present invention.

As shown in FIG. 1, the transmission line monitoring system 1 monitors the transmission line 2 by receiving power from the electromagnetic induction type power generation device 3 that generates power by the current I flowing through the transmission line 2 and the electromagnetic induction type power generation device 3. It includes an IoT device 4 that operates, and a data communication unit 5 that transmits monitoring data acquired by the IoT device 4 by wireless communication or wired communication. The electromagnetic induction type power generation device 3 serves as a power source for the IoT device 4 and the data communication unit 5, and the IoT device 4 and the data communication unit 5 are connected to the output terminal of the electromagnetic induction type power generation device 3. The type of the IoT device 4 is not particularly limited, and may be various sensor modules for measuring the physical or electrical state of the transmission line 2, a remote surveillance camera, or the like. The data communication unit 5 transmits the data collected by the IoT device 4 to the server.

The transmission line 2 is preferably an underground transmission line, and more preferably a high-voltage transmission line having a transmission voltage of 66 kV or more. Since the underground power transmission line is laid in a narrow cave, the working environment is poor and it is difficult to install and maintain the IoT device 4. An alternating current of a commercial frequency (50 Hz or 60 Hz) flows through the transmission line 2, and an alternating magnetic field is generated around the transmission line 2. The magnitude of the alternating magnetic field changes depending on the magnitude of the current flowing through the transmission line 2.

The electromagnetic induction type power generation device 3 includes a current transformer 10 attached to the transmission line 2 and a power supply circuit 20 connected to the current transformer 10. Although not shown, the power supply circuit 20 includes a rectifier circuit that rectifies the AC output voltage from the current transformer 10 and a regulator circuit that limits the DC voltage output from the rectifier circuit to a constant voltage level.

FIG. 2 is a schematic side sectional view showing the configuration of the current transformer 10 according to the first embodiment of the present invention. Further, FIG. 3 is a plan view showing the configuration of the current transformer 10.

As shown in FIGS. 2 and 3, the current transformer 10 includes a magnetic core 11 surrounding a power transmission line 2 composed of a conducting wire portion 2a covered with an insulator 2b, and a coil 15 wound around the magnetic core 11. ing. The magnetic core 11 extends in a substantially U-shaped first core portion 12 surrounding the transmission line 2 and in the Y direction (second direction) orthogonal to the Z direction (first direction) which is the extending direction of the transmission line 2. It has a substantially rod-shaped second core portion 13 that connects _one tip portion 12c ₁ of the first core portion 12 and the other tip portion 12c ₂ . The coil 15 is wound around the second core portion 13, and the coil shaft is oriented in the Y direction. Although not shown, it is preferable that the first core portion 12 and the second core portion 13 are housed in a resin case, respectively.

The first core portion 12 is formed by forming a thin plate-shaped or sheet-shaped magnetic member in a substantially U-shape. The first core portion 12 is preferably an elastic member, preferably made of nickel. The humidity inside the cave where the underground power transmission line is laid is high, and the metal is rusty easily, but nickel is hard to rust, so the secular change of magnetic permeability can be suppressed. The first core portion 12 may have a folded shape that makes a half circumference along the outer peripheral surface of the transmission line 2 and returns to the original position.

The material of the first core portion 12 may be a nickel steel plate or permalloy, or may be a magnetic sheet in which ferrite powder is dispersed in a resin sheet. Since the magnetic sheet is very thin and highly flexible, it can be wound along the outer peripheral surface of the power transmission line 2 and is easy to install.

The second core portion 13 is preferably made of a magnetic material having a higher magnetic permeability than the first core portion 12, and is preferably ferrite. As described above, a material having a high magnetic permeability is used for at least a part of the magnetic core 11, and a coil 15 is wound around this part, so that a desired generated power can be secured. Further, by using a material having a high magnetic permeability for the second core portion 13, the cross-sectional area of the second core portion 13 can be reduced to reduce the size.

The length L ₁ of the second core portion 13 is preferably larger than the diameter D of the conductor portion 2a of the transmission line 2. If the length L ₁ of the second core portion 13 is smaller than the diameter D of the conductor portion 2a of the transmission line 2, the power generation efficiency is significantly reduced. However, when the length L ₁ of the second core portion 13 is larger than the diameter D of the conductor portion 2a of the transmission line 2 can ensure a desired power generation efficiency.

As shown in FIG. 2, the thickness t ₁ of the first core portion 12 in the direction orthogonal to the extending direction of the first core portion 12 as seen from the extending direction (Z direction) of the transmission line 2 orthogonal to the paper surface is , T is thinner than the thickness t ₂ of the second core portion 13 in the X direction (third direction) orthogonal to the Z direction and the Y direction. Therefore, the magnetic core 11 can be partially thinned, and even if a plurality of power transmission lines 2 are bundled, the magnetic core 11 can be easily attached.

As shown in FIG. 3, when viewed from the Y direction (second direction) orthogonal to the extending direction of the transmission line 2, the first core portion 12 includes a base portion 12a accommodating the transmission line 2 and a second core. It has a tapered portion 12b whose width gradually narrows toward the mounting position of the portion 13, and a tip portion 12c to which the second core portion 13 is mounted, and the width W _1c of the tip portion 12c is the width of the second core portion 13. Wider than W ₂ , the width W _1a of the base portion 12a is even wider than the width W _1c of the tip portion 12c. That is, the maximum width of the first core portion 12 in the Z direction viewed from the Y direction is wider than the maximum width of the second core portion 13 in the Z direction viewed from the Y direction.

When the 12 thickness t ₁ of the first core portion is thinned, the magnetic core 11 is partially thinned so that it can be easily attached to the transmission line 2, but the width of the magnetic path seen from the first direction is narrow. Therefore, the power generation efficiency is lowered as it is. However, by widening the width of the magnetic path seen from the second direction, as much magnetic flux generated around the transmission line 2 can be collected and sent to the second core portion 13, and the cross-sectional area of the magnetic path can be increased. It is possible to prevent a decrease in power generation efficiency due to a decrease in power generation.

In the present embodiment, the second core portion 13 is detachably configured with respect to the first core portion 12. Therefore, the first core portion 12 can be removed to accommodate the transmission line 2 in the first core portion 12, whereby the transmission line 2 can be clamped. When the second core portion 13 is attached to the first core portion 12, the tip surface of the second core portion 13 is connected directly to the inner end surface of the first core portion 12 or through a gap. As a result, a closed magnetic path composed of a combination of the first core portion 12 and the second core portion 13 is formed.

FIG. 4 is a diagram showing an example of a method of attaching the current transformer 10 to the transmission line 2.

As shown in FIG. 4A, first, the second core portion 13 is removed from the first core portion 12. Next, as shown in FIG. 4 (b), the transmission line 2 is set in the first core portion 12, and further, as shown in FIG. 4 (c), the second core portion 13 is attached to the first core portion 12. As described above, the current transformer 10 can be attached to the transmission line 2.

FIG. 5 is a schematic view showing a state in which one current transformer 10 is attached to each of three bundles of power transmission lines.

As shown in FIG. 5, when the three transmission lines 2A, 2B, and 2C corresponding to each of the three-phase alternating currents are bundled and the gap G between the two adjacent transmission lines is very narrow, it is thick. It is difficult to attach a conventional clamp-type current transformer composed of a magnetic core. However, when the first core portion 12 is thin as in the present embodiment, it is easy to attach the current transformer 10 to each of the transmission lines 2A, 2B, 2C. It is desirable that the mounting positions of the three current transformers 10 in the extending direction of the transmission lines 2A, 2B, and 2C do not overlap each other.

In the electromagnetic induction type power generation device 3, the secondary current increases as the current flowing through the transmission line 2 increases. Therefore, when the current flowing through the transmission line 2 is very large, the amount of power generation also becomes very large. Even though the amount of power generation is increasing in this way, if the IoT device 4 is operating at a constant power consumption, a large amount of extra power will be generated, so it will be converted to heat, etc. It is necessary to consume surplus power in some way.

However, when the surplus electric power is converted into heat, the temperature of the IoT device 4 rises unnecessarily, which may accelerate the deterioration of the parts and elements in the IoT device 4. Further, since the dynamic range of the current flowing through the transmission line 2 is as wide as 50A to 3000A, a large current of several thousand amperes or more may flow through the transmission line 2, but all the surplus power generated by the large current is heated. It is extremely difficult to convert to. Since the IoT device 4 installed on the power transmission line is required to operate stably for a long period of 10 years or more once it is installed, the deterioration of the characteristics of the IoT device 4 due to high temperature or the like is prevented as much as possible. It is desirable to do.

The current transformer 10 according to the present embodiment has lower power generation efficiency than, for example, the conventional current transformer 10 using a ring-shaped ferrite core. However, when the current transformer 10 is permanently installed to supply power to the low power consumption IoT device 4, a large amount of power generation is not required. Since the current transformer 10 according to the present embodiment has a magnetic core structure that emphasizes ease of attachment and durability rather than power generation, it is possible to realize a power source that is advantageous to the IoT device 4.

As described above, in the current transformer 10 according to the present embodiment, since the first core portion 12 constituting the magnetic core 11 is made of a thin magnetic material, the size and weight of the magnetic core 11 can be reduced. It can be easily attached to the transmission line 2.

FIG. 6 is a cross-sectional view showing the configuration of the current transformer 10 according to the second embodiment of the present invention.

As shown in FIG. 6, the feature of the current transformer 10 is that the first variable member 12 is formed by a combination of the first variable member 12m and the second variable member 12n in which the first core portion 12 can be elastically deformed, and the first variable member 12m is curved. It has a structure in which the tip portion and the curved tip portion of the second variable member 12n overlap each other. Then, since the inner diameter area of the first core portion 12 changes as the degree of overlap of the first variable member 12m and the second variable member 12n changes, it can be attached to various power transmission lines 2 having different wire diameters. Further, when the transmission line 2 is attached to the magnetic core 11, the transmission line 2 can be inserted by widening the tip of the first variable member 12m and the tip of the second variable member 12n to form an opening. it can.

7 (a) and 7 (b) are schematic cross-sectional views showing the configuration of the current transformer 10 according to the third embodiment of the present invention.

As shown in FIGS. 7A and 7B, the feature of the current transformer 10 is that it further includes a capacitor 16 connected in series or in parallel with the coil 15, and the coil 15 and the capacitor 16 form a resonance circuit. There is a point. In particular, FIG. 7A shows an LC series resonant circuit, and FIG. 7B shows an LC parallel resonant circuit. According to this embodiment, the power generation efficiency of the current transformer 10 can be increased.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention, and these are also the present invention. It goes without saying that it is included in the range.

For example, the current transformer connected to the underground transmission line according to the present embodiment is taken as an example, but it is also possible to connect to another transmission line such as an overhead transmission line.

1 Transmission line monitoring system 2,2A, 2B, 2C Transmission line (underground transmission line)
2a Transmission line lead wire 2b Transmission line insulator 3 Electromagnetic induction power generation device 4 IoT device 5 Data communication section 10 Current transformer 11 Magnetic core 12 1st core section 12a 1st core section base section 12b 1st core section Tapered part 12c Tip part of the first core part 12c ₁ One tip part 12c ₂ Tip part of the other 12m 1st variable member 12n 2nd variable member 13 2nd core part 15 Coil 16 Condenser 20 Power supply circuit G 2 transmission lines Gap between

Claims (12)

With a magnetic core that can be attached to an insulated power transmission line,
A coil wound around the magnetic core is provided.
The magnetic core is
The first core part that surrounds the transmission line in a substantially U shape,
It has a second core portion extending in a second direction orthogonal to the first direction, which is the extending direction of the transmission line, and connecting one end portion and the other end portion of the first core portion. ,
The coil is wound around the second core portion, and is wound around the second core portion.
The thickness of the first core portion in a direction orthogonal to the extending direction of the first core portion as viewed from the first direction is the thickness of the first core portion in the first direction and the second direction orthogonal to the second direction. A current transformer characterized by being thinner than the thickness of the core. The maximum width of the first core portion in the first direction when viewed from the second direction is
The current transformer according to claim 1, which is wider than the maximum width of the second core portion in the first direction when viewed from the second direction. The current transformer according to claim 1 or 2, wherein the second core portion is detachably configured with respect to the first core portion. The current transformer according to any one of claims 1 to 3, wherein the magnetic permeability of the second core portion is higher than the magnetic permeability of the first core portion. The current transformer according to any one of claims 1 to 4, wherein the first core portion is made of nickel. The current transformer according to any one of claims 1 to 5, wherein the second core portion is made of ferrite. The current transformer according to any one of claims 1 to 6, wherein the length of the second core portion is larger than the diameter of the lead wire portion of the transmission line. The current transformer according to any one of claims 1 to 7, wherein the first core portion has elasticity. The current transformer according to any one of claims 1 to 8, wherein the inner diameter area of the first core portion changes according to the thickness of the transmission line. The current transformer according to any one of claims 1 to 9, further comprising a capacitor connected to the coil, wherein the coil and the capacitor constitute a resonance circuit. The current transformer according to any one of claims 1 to 10 and
An electromagnetic induction type power generation device including a power supply circuit connected to the current transformer. The electromagnetic induction type power generation device according to claim 11 and
An IoT device that receives power from the electromagnetic induction power generation device and monitors the transmission line.
A transmission line monitoring system including a data communication unit that transmits monitoring data acquired by the IoT device by wireless communication or wired communication.

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