Underground power transmission line fault detection training device

Abstract

The objective is to provide a portable underground power transmission line fault detection training device that has a simulated fault point that can be arbitrarily positioned to simulate a ground fault in an underground power transmission line. [Solution] The underground power transmission line fault location training device comprises a plurality of interconnected terminals indicating a normal state and a simulated fault point indicating a ground fault state, connected by a simulated cable, pulse detectors 1 and 2 positioned at both ends of the simulated cable, and a pulse measuring instrument. The interconnected terminals and the simulated fault point can be rearranged to any position. A DC voltage is applied from one end of the simulated cable to discharge at the simulated fault point, and the pulse measuring instrument determines the position of the simulated fault point based on the time difference of the pulses that reach pulse detectors 1 and 2.

Description

Technical Field

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[0001] The present invention relates to a training device for detecting underground transmission line faults.

Background Art

[0002] Power outages due to ground faults in power cables have a significant impact on social functions. Therefore, when a fault such as a ground fault occurs in a power cable, it is important to quickly and accurately detect the fault point in order to restore the fault point at an early stage. Since the underground transmission line cannot visually observe the fault point, electrical measurement is performed to detect the fault point, and the work of replacing the target section is carried out.

[0003] Normally, for fault point calibration, the Murray loop method that uses the principle of a bridge and measures the resistance to the accident point with the core wire of the faulty cable as one side of the bridge, or the pulse radar method that captures the reflection of an electrical pulse is used. Recently, as a preventive measure for ground fault accidents caused by cable movement due to phenomena such as the wave riding phenomenon (the phenomenon where the cable under the road deflects due to the load and vibration of the vehicle and the cable moves along the vehicle traveling direction), a program has been developed that causes a computer to execute a process of inputting certain information into a learned model that has been learned to estimate the movement amount and outputting the estimation result (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the event of a ground fault in an underground power distribution system, it is desirable that the maintenance department possesses the skills and techniques to quickly and accurately locate the fault in order to restore power as soon as possible. Therefore, the maintenance department regularly trains its workers to acquire and maintain fault location techniques and skills. However, training equipment with fixed fault locations makes it difficult to master the technique through repeated practice. In addition, large-scale training equipment is location-dependent, which presents challenges in terms of where and when it can be used.

[0006] This invention was proposed in view of the above circumstances, and aims to provide a portable underground power transmission line fault detection training device for pulse radar that has a simulated fault point whose position can be freely set. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and embodiments of the present invention may include the following configurations. (1) The underground power transmission line fault location detection training device is Connected by simulated cables, Multiple interconnected terminals showing a normal state and a simulated fault point showing a ground fault state, The pulse detector 1 and pulse detector 2 are positioned at both ends of the aforementioned simulated cable, Equipped with a pulse measuring instrument, The aforementioned connecting terminal and the aforementioned simulated fault point can be rearranged to any desired location. An underground power transmission line fault location detection training device characterized by applying a DC voltage from one end of the simulated cable to discharge at the simulated fault point, and determining the location of the simulated fault point using the pulse measuring instrument based on the time difference of the pulses that reach the pulse detector 1 and the pulse detector 2. (2) The connecting terminal comprises two connecting terminals, a conductor, and an earth terminal. The two connecting terminals are electrically connected to each other via a conductor. The simulated fault point comprises the two connecting terminals, the ground terminal, and the switching unit. The underground power transmission line fault location detection training device according to (1), characterized in that the switching unit becomes the simulated fault point by a sphere gap formed by arranging a sphere electrode connected to one of the connection terminals and a sphere electrode connected to the ground terminal opposite each other. (3) The underground power transmission line fault location training device according to (1) or (2), wherein the simulated cable is a coaxial cable with a diameter of 1 to 10 mm. (4) The underground power transmission line fault location detection training device according to (1), further comprising a high-voltage power supply device that applies a DC voltage from one end of the simulated cable. (5) The underground power transmission line fault location detection training device according to (4), wherein the high-voltage power supply device is a high-voltage generation module that boosts a voltage of 1,000V or less to 5,000 to 100,000V. [Effects of the Invention]

[0008] The training device of the present invention has multiple simulated fault points whose positions can be freely set, thereby increasing the variety of training. Furthermore, because the training device is lightweight and compact, it is portable, allowing training to be conducted regardless of location or time. Through the acquisition of fault location techniques by workers, it can be used to improve fault recovery techniques. [Brief explanation of the drawing]

[0009] [Figure 1] Diagram showing an overview of the underground power transmission line fault location training device. [Figure 2] Enlarged view of the simulated fault point [Figure 3] Appearance of the underground power transmission line fault location training device [Figure 4] Example of use of the underground power transmission line fault point detection training device of the present invention [Figure 5] Diagram showing an overview of the high-voltage power supply equipment. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described with reference to Figure 1. Figure 1 is a diagram showing an overview of the underground power transmission line fault location training device of this embodiment. The underground power transmission line fault location training device of the present invention is a loop-type training device comprising a plurality of interconnection terminals 8 indicating a normal state and a simulated fault point 7 indicating a ground fault state (hereinafter, the plurality of interconnection terminals 8 and the simulated fault point 7 together may be referred to as the simulated fault device 1), connected by a simulated cable, pulse detectors 1(2) and pulse detectors 2(3) arranged at both ends of the simulated cable, and a pulse measuring instrument 4. A DC voltage is applied from one end of the simulated cable. The training device of this invention employs a "discharge detection type pulse radar method" among pulse radar types. The respective components are described below.

[0011] <Simulated Cable> In this invention, the connecting terminal 8, the simulated fault point 7, the pulse detector 1(2), the pulse detector 2(3), and the pulse measuring instrument 4 are connected by a simulated cable 5. More specifically, each component is connected by the core wire of the simulated cable 5. The type of simulated cable 5 is not limited as long as it is a cable-like object with a shielding layer that can electrically connect each device. A coaxial cable is a cable in which a shielding layer is arranged to cover the copper wire (hereinafter sometimes referred to as the core wire) that transmits signals. A coaxial cable is not particularly limited as long as the shielding layer covers the core wire, but from the viewpoint of ease of availability and durability, a round cable is preferred in which the core wire is surrounded by a tubular insulating layer, further covered with a shielding layer, and finally covered with an outer sheath. Although it is used for the internet and television / video distribution, in this invention, it is preferable to use a coaxial cable because it can be compactly stored even when the cable is long and can propagate pulse waves because it has a shielding layer.

[0012] A coaxial cable will be specifically described. The core wire is preferably, for example, a stranded wire formed by combining a plurality of conductive elementary wires, a columnar conductor composed of a single metal bar having a solid structure inside, a tubular conductor having a hollow structure inside, or the like. A combination of these plural types of conductors may also be used. As the columnar conductor, for example, a single-core wire or a bus bar is preferable. As the material of the core wire, for example, a metal material such as a copper-based or aluminum-based material is preferable. The insulating layer is preferably made of an insulating material such as a synthetic resin mainly composed of a polyolefin-based resin such as crosslinked polyethylene or crosslinked polypropylene. The shielding layer is preferably a copper-based material made of copper or a copper alloy excellent in electromagnetic wave shielding property, or an aluminum-based material made of aluminum or an aluminum alloy having a small specific gravity. It is preferable to use the coaxial cable (3d-2v) of ESCO Corporation.

[0013] When the outer diameter of the coaxial cable becomes large, it becomes heavy and its workability deteriorates. Therefore, the diameter of the coaxial cable is preferably 1 to 10 mm, more preferably 2 to 8 mm. The total length of the coaxial cable is not particularly limited as long as it can be accommodated inside the ground transmission line fault point exploration training device.

[0014] <Simulated fault device> The simulated fault device 1 of the present invention has a plurality of cooperating terminals 8 indicating a normal state and simulated fault points 7. The simulated fault points 7 can be arbitrarily set from among the plurality of cooperating terminals 8. The cooperating terminals 8 indicate a normal state, and the simulated fault points 7 indicate a ground fault state. Preferably, there are two or more cooperating terminals 8, more preferably three or more. Although more increases the variations of training, since the device itself becomes heavy, preferably there are 10 or less, more preferably 6 or less. By having a plurality of cooperating terminals 8, the selection range for setting the simulated fault points increases, so that the variations of the fault locations can be increased, resulting in good training.

[0015] The cooperating terminal 8 includes two connection terminals (11a or 11b) and a ground terminal 12. The two connection terminals (11a or 11b) are electrically connected to each other via a conductor 15.

[0016] The plurality of cooperating terminals 8 are preferably connected in series by the core wire of a coaxial cable via the connection terminals 11a or 11b. It is preferably connected in series by the core wire of a coaxial cable of 5 to 50 m. When there are three or more cooperating terminals 8, the lengths of the coaxial cables connecting the respective cooperating terminals 8 may be the same or different. For example, the length of the coaxial cable connecting the cooperating terminal A and the cooperating terminal B in FIG. 4 may be the same as or different from the length of the coaxial cable connecting the cooperating terminal B and the cooperating terminal C.

[0017] The cooperating terminal 8 and the simulated fault point 7 can be rearranged at arbitrary positions. That is, the simulated fault point 7 can be arbitrarily set among the plurality of cooperating terminals 8. More specifically, by installing a switching unit 14 described later in the cooperating terminal 8, the cooperating terminal 8 becomes the simulated fault point 7. It is preferable to set one simulated fault point 7 in the simulated fault device (that is, one among the plurality of cooperating terminals 8).

[0018] An enlarged view of the simulated fault point 7 is shown in FIG. 2. The simulated fault point includes, in addition to the two connection terminals and the ground terminal, a switching unit.

[0019] The ground terminal 12 is a terminal electrically connected to the shielding layer of the coaxial cable, and a lead wire is attached to the shielding layer for grounding. Thereby, since the potential of the shielding layer becomes almost 0 V, it is safe even if one touches the surface of the cable. Also, since the potential distribution (electric field) inside the cable becomes uniform, it can be operated in a stable state. Therefore, the training device of the present invention is portable, and stable training is possible even at the place where it is carried.

[0020] The switching unit 14 has a spherical gap configured by arranging a spherical electrode 13 connected to any one of the connection terminals (11a or 11b) and a spherical electrode 13 connected to the ground terminal 12 to face each other. It is possible to select which connection terminal to connect to.

[0021] The space between a pair of spherical electrodes is called a spherical gap. Compared to a needle gap, which is the gap between a needle-shaped electrode and a flat or spherical electrode, a spherical gap has a larger area of ​​equielectric field between the gaps, and even if the surface of the spheres becomes rough with use, the change in operating voltage is small. Therefore, it is preferable to use a spherical gap in training devices that require durability, as in the present invention. Furthermore, a spherical gap is preferable to a flat gap, which is a structure in which two flat electrodes face each other, because it is less affected by electric field strain at the ends. It is preferable that the pair of spherical electrodes have the same diameter. The material is not limited, but brass is preferred because it is inexpensive. It is preferable that the spheres have a smooth surface and uniform curvature, and that there are no irregularities in the spark region of the spheres. It is preferable that the length of the gap is 0.05 to 0.4 times the diameter of the spheres.

[0022] In this invention, when a DC voltage is applied, the sphere gap discharges and generates pulses, resulting in a simulated ground fault condition. This makes it possible to generate a fault that simulates a ground fault. The DC voltage may be applied from a DC power supply or from a high-voltage power supply device described later. It is preferable to apply 1 to 10 single pulses per second, and more preferably 2 to 5 single pulses per second.

[0023] <Pulse detectors and pulse measuring instruments> The underground power transmission line fault detection training device of the present invention is equipped with pulse detectors 1(2) and 2(3) at both ends of a simulated cable. In this invention, a discharge detection type pulse radar method is employed among pulse radar methods. A DC voltage is applied from one end of the simulated cable to cause a discharge at the simulated fault point, and the pulses generated at that time are detected by pulse detectors 1(2) and 2(3) provided at both ends of the simulated cable. The position of the simulated fault point is measured by a pulse measuring instrument based on the time difference of the pulses that reach pulse detectors 1(2) and 2(3).

[0024] Let's explain this in more detail. When a DC voltage is applied from one end of a simulated cable, causing a discharge at the simulated fault point, a time difference t occurs in the first wave of the discharge pulse that reaches the pulse detectors 1(2) and 2(3) located at both ends of the simulated cable. For example, in Figure 4, when a DC voltage is applied from the pulse detector 1(2) side, the pulse arriving from the simulated fault point in the shortest time is detected by pulse detector 1(2), and the pulse reaching the far end is detected by pulse detector 2(3). This time difference can be expressed by equation (1), where v is the propagation speed.

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[0025] Prior to the above measurement, the pulse propagation speed v is calibrated. For example, by causing a flashover in the sphere gap at the measurement end of the phase to which pulse detector 1(2) is connected, the time difference T between the pulse detected by pulse detector 1(2) and the pulse detected by pulse detector 2(3) after propagating along the entire length L of the cable can be calculated as shown in equation (2).

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[0026] <High-voltage power supply equipment> Generally, the discharge detection type pulse radar method can be used when the resistance value of the simulated fault point is high and discharge-prone. High resistance refers to a resistance of 5 MΩ or more.

[0027] In this invention, it is preferable to apply a DC voltage in order to reproduce a simulated ground fault condition. Therefore, as shown in Figure 4, it is preferable to use a high-voltage power supply device 6 that generates discharge pulses to cause a discharge at the simulated fault point.

[0028] Typical high-voltage power supply devices weigh about 100 kg, making them heavy and requiring considerable effort to transport. The high-voltage power supply device used in this invention is preferably lightweight so that it can be easily carried along with the training device. While there are no specific requirements for the device's configuration as long as it can apply high-voltage pulses, it is preferable that it consists of a down transformer 22, a bridge diode 23, and a high-voltage generation module 24, as shown in Figure 5.

[0029] The power supply 21 in Figure 5 is a commercial power supply. For example, a commercial power supply with a voltage of 100V is used. The step-down transformer 22 transforms the power supplied from the power supply 21. For example, when 100V is input from the commercial power supply, it is preferable to output 5 to 20V, and more preferably 6 to 10V. The bridge diode 23 is a rectifier circuit that converts AC to DC. Since the high-voltage generation module requires DC power, the power transformed by the step-down transformer 22 is full-wave rectified by the bridge diode and converted from AC to DC. The high-voltage generation module 24 generates a high voltage and discharges it at the simulated fault point.

[0030] The high-voltage power supply device 6 is preferably connected to the detection end, which is one end of the simulated cable. For example, as shown in Figure 4, the high-voltage power supply device 6 is preferably connected between the simulated fault device 1 and the pulse detector 1(2). Alternatively, it is preferably connected between the simulated fault device 1 and the pulse detector 2(3). The high-voltage power supply device 6 is preferably one that uses a high-voltage generation module within the device to boost a voltage of 1,000V or less supplied from commercial power to 5,000 to 100,000V.

[0031] <Use of the underground power transmission line fault location training device of the present invention> The underground power transmission line fault location detection and training device of the present invention can generate any simulated fault point using a simulated fault device. For example, in Figure 4, if a sphere gap is placed at position B, applying a DC voltage will result in a simulated ground fault at B. In this case, t: Time difference (μs) between pulse detector 1(2) and pulse detector 2(3) L: Total length (m) of the coaxial cable from pulse detector 1(2) through simulated fault point 7 to pulse detector 2(3) l: Distance (m) from pulse detector 1(2) to simulated fault point If v is the pulse propagation speed in the cable (m / μs) (which is determined in advance), then the distance l from pulse detector 1(2) to the simulated fault point can be calculated using equation (3).

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[0032] According to the underground power transmission line fault location training device of the present invention, the simulated fault point 7 can be arbitrarily set from multiple interconnected terminals 8, thereby increasing the variety of training and preventing training from becoming monotonous. Furthermore, because the underground power transmission line fault location training device of the present invention is lightweight and compact, it is portable and can be used for training regardless of location or time. [Explanation of Symbols]

[0033] 1: Simulated failure device 2: Pulse detector 1 3: Pulse detector 2 4: Pulse measuring instrument 5: Simulated cable (coaxial cable) 6: High-voltage power supply equipment 7: Simulated failure point 8: Connected devices 11a, 11b: Connection terminal 12: Ground terminal 13: Ball electrode 14: Switching section 15: Conductors 21: Power supply 22: Step-down transformer 23: Bridge Diode 24: High-voltage generation module

Claims

1. The underground power transmission line fault location detection training device is Connected by simulated cables, Multiple interconnected terminals showing a normal state and a simulated fault point showing a ground fault state, The pulse detector 1 and pulse detector 2 are positioned at both ends of the simulated cable, Equipped with a pulse measuring instrument, The aforementioned connecting terminal and the aforementioned simulated fault point can be rearranged to any desired location. An underground power transmission line fault location detection training device characterized by applying a DC voltage from one end of the simulated cable to discharge at the simulated fault point, and determining the location of the simulated fault point using the pulse measuring instrument based on the time difference of the pulses that reach the pulse detector 1 and the pulse detector 2.

2. The aforementioned connecting terminal comprises two connecting terminals, a conductor, and a ground terminal. The two connecting terminals are electrically connected to each other via a conductor. The simulated fault point comprises the two connecting terminals, the ground terminal, and the switching unit. The underground power transmission line fault location detection training device according to claim 1, characterized in that the switching unit becomes the simulated fault point by a sphere gap formed by arranging a sphere electrode connected to one of the connection terminals and a sphere electrode connected to the ground terminal opposite each other.

3. The underground power transmission line fault location detection training device according to claim 1 or 2, wherein the simulated cable is a coaxial cable with a diameter of 1 to 10 mm.

4. The underground power transmission line fault location detection training device according to claim 1, further comprising a high-voltage power supply device that applies a DC voltage from one end of the simulated fault device.

5. The underground power transmission line fault location detection training device according to claim 4, wherein the high-voltage power supply device is a high-voltage generation module that boosts a voltage of 1,000V or less to 5,000 to 100,000V.

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