JP7039149B2 - Failure point distance detector - Google Patents

Description

The present invention relates to a fault point distance detecting device that detects a fault point in a power line as a distance from a power transmission end to a fault point.

It is important to maintain, monitor, and maintain the insulation performance of low-voltage, high-voltage, and extra-high-voltage AC power circuits and DC power circuit cables and wires (hereinafter referred to as power lines) in indoor distribution lines, outdoor distribution lines, and underground distribution lines. It is a business. In the Electricity Business Law, the maintenance and supervision of these facilities is stipulated by the safety regulations, and the maintenance and supervision of electric power lines is carried out by the electric power companies and the installers of private electric facilities.

The wiring method of the AC power circuit includes a three-phase three-wire system, a three-phase four-wire system, a single-phase two-wire system, a single-phase three-wire system, and the like, and a DC power circuit includes a DC two-wire system. Of these power circuits, in the AC power circuit, if the insulation performance of the power line deteriorates, is defective, or a ground fault (hereinafter referred to as a failure) occurs, the zero phase component will occur, so monitor the zero phase. Therefore, it is possible to detect that a failure has occurred in any system of the power circuit. Then, in order to determine which phase of the power circuit is out of order, the failure phase can be obtained by individually measuring the insulation resistance of each phase of the power circuit with an insulation resistance tester. Further, the failure phase can be obtained by using Japanese Patent Application No. 2019-141054 previously filed by the present applicant.

In a DC power circuit, a failure can be detected by a DC leakage detector, and the failure phase is obtained by individually measuring the insulation resistance of each phase of the power circuit with an insulation resistance tester in the same way as an AC power circuit. be able to.

FIG. 13 shows a three-phase three-wire power circuit in which a faulty phase is obtained by individually measuring the insulation resistance of each of the three phases of the three-phase three-wire power circuit with an insulation resistance tester. It is a circuit diagram. This three-phase power circuit is composed of three-phase RST-phase power lines from the transmission end 11 to the terminal 12. Now, it is assumed that a failure has occurred in the T phase of the three RST phases. That is, it is assumed that the R phase and the S phase are the healthy phase and the T phase is the faulty phase. Rr is the DC resistance of the R-phase power line, Rs is the DC resistance of the S-phase power line, and Rt is the DC resistance of the T-phase power line. Of the DC resistance Rt of the T-phase power line, Rt1 is the DC resistance from the transmission end 11 to the failure point G, Rt2 is the DC resistance from the terminal 12 to the failure point G, and Rt = Rt1 + Rt2.

If a failure occurs in any of the RST phases, a zero phase component is generated in the three RST phases. Therefore, when the zero-phase component is detected in the three-phase RST phase, the three-phase power circuit is stopped, and the insulation resistance tester 13 is sequentially connected to each of the three phases to obtain the fault current Ig and the fault resistance Rg. In this case, if there is a branch power circuit in the middle of the three-phase power circuit, the end of the branch power circuit is opened.

The fault resistance Rg to ground insulation resistance value is usually considered to be about 0Ω to several tens of MΩ. In the power circuit of FIG. 13, the decrease in the insulation resistance value to the ground is a lumped constant, and the capacitance to the ground is a distribution constant. Capacitance can be excluded.

In FIG. 13, the insulation resistance tester 13 is connected to the T phase, which is the fault phase, and the fault current Ig and the fault resistance Rg are obtained. In this case, the DC current of the insulation resistance tester 13 is gradually increased while monitoring the current value of the ammeter 14 of the insulation resistance meter 13. This is done by changing the output current of the DC power supply device 15 to which the positive terminal is grounded by the variable resistor 16. The DC current of the insulation resistance tester 13 may be gradually increased by directly varying the output voltage of the DC power supply device 15 instead of the variable resistor 16. In this case, it is preferable that the DC voltage can be adjusted from 0 V to about 10 kV. Assuming that the failure point voltage is Eg, the failure resistance Rg is obtained by Rg = Eg / Ig.

In this way, the failure resistance Rg, the failure current Ig, and the failure point voltage Eg of the failure point G can be obtained, but the position of the failure point G is unknown. Therefore, it is required to detect the position of the failure point G in the failure phase.

Here, as a device for detecting the position of the failure point G in the failure phase, a DC voltage is applied to the conductor at one end of the power cable, and the first pulse wave propagated to the conductor at one end of the power cable is processed. The signal waveform was obtained by processing the second pulse wave propagated to the conductor at the other end of the power cable as the second signal waveform, and the phase difference between the first signal waveform and the second signal waveform was obtained for each frequency. There is one that can detect the fault point with high accuracy based on the phase difference (see Patent Document 1). In addition, there is also one in which insulation failure of a cable having a shield layer is detected by the principle of Wheatstone bridge (see Non-Patent Document 1).

Japanese Unexamined Patent Publication No. 2007-232623

Fujikura Dia Cable Ltd., Live-line sheath insulation defect measuring device, https://www.fujikura-dia.co.jp/products/lilia150T

However, in Patent Document 1, when detecting a failure point, an operation of processing a pulse signal propagated to the end of a power cable and an operation of obtaining a phase difference between the processed first signal wave and the second signal wave are performed. It will be necessary, and an advanced arithmetic processing device will be required. Further, in Non-Patent Document 1, the target is poor insulation of a cable having a shield layer, and since it has a Wheatstone bridge circuit, it is expensive.

Many low-voltage power circuits for indoor wiring are installed in buildings and factories, and those that have been laid for more than 50 years, when many power lines are laid on the laying route, or where the ceiling is high from the floor. It is often laid in. Further, since the power line is housed in the pipe outside the building or on the roof, it is practically impossible to detect and specify the position even if the insulation failure occurs at the intermediate position of the power line. Therefore, when a power line with abnormal insulation is identified, the failure section is investigated by removing and replacing the entire power line or by cutting and investigating the middle of the power line. Therefore, it is required to detect the position of the accident point on the power line with high accuracy and at low cost with a simple configuration.

An object of the present invention is to target the power lines of a power circuit such as a three-phase three-wire system, a three-phase four-wire system, a single-phase two-wire system, a single-phase three-wire system, and a DC two-wire system, with a simple configuration and at low cost. It is an object of the present invention to provide a fault point distance detecting device capable of detecting a fault point in a power line as a distance from a power transmission end to a fault point.

The fault point distance detecting device according to the invention of claim 1 is
When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the DC power supply device passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the failure phase, and passes through the confluence point on the transmission end side. A fault phase current detector that detects the fault phase current I1 flowing through the first ground fault circuit that returns to the negative terminal of
From the positive terminal of the DC power supply device, the DC power supply passes through the failure point, branches at the failure point, passes through the termination of the failure phase and the short-circuit device, passes through the healthy phase, and passes through the confluence point on the transmission end side. A healthy phase current detector that detects the healthy phase current I2 flowing through the second ground fault circuit that returns to the negative terminal of the device, and
A total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The faulty phase current detector and the healthy phase current detector are ammeters whose internal resistance is smaller than the resistance value of the power line.
The faulty phase current I1 / the total current I3 is defined as the first index value E1, the healthy phase current I2 / the total current I3 is defined as the second index value E2, and the distance of the power line from the transmission end to the end is L. When
The distance x1 from the power transmission end to the failure point is calculated separately by the following equations (a) and (b), respectively.
x11 = 2L · (1-E1) ... (a), x12 = 2L · E2 ... (b)
The distance x1 from the power transmission end to the failure point is obtained as the average value of the calculated value x11 and the calculated value x12.
The distance x2 from the end point to the failure point is calculated separately by the following equations (c) and (d), respectively.
x21 = L · (2E1-1) ... (c), x22 = L · (1-2E2) ... (d)
It is characterized in that the distance x2 from the end point to the failure point is obtained as an average value of the calculated value x21 and the calculated value x22.

The fault point distance detecting device according to the invention of claim 2 is
When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the DC power supply device passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the failure phase, and passes through the confluence point on the power transmission end side. The first ground fault circuit returning to the negative terminal and the positive terminal of the DC power supply device pass through the failure point, branch at the failure point, pass through the termination of the failure phase and the short circuit device, and pass through the healthy phase. A switching device that switches the second ground fault circuit that passes through the confluence on the power transmission end side and returns to the negative terminal of the DC power supply device at the power transmission end of the power line.
When connected to the first ground fault circuit by switching between the first ground fault circuit and the second ground fault circuit in the switching device, the fault phase current I1 flowing in the first ground fault circuit is detected and said. A combined current detector that detects the healthy phase current I2 flowing in the second ground fault circuit when connected to the second ground fault circuit, and
The combined current detector is an ammeter whose internal resistance is smaller than the resistance value of the power line.
A total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The faulty phase current I1 / the total current I3 is defined as the first index value E1, the healthy phase current I2 / the total current I3 is defined as the second index value E2, and the distance of the power line from the transmission end to the end is L. When
The distance x1 from the power transmission end to the failure point is calculated separately by the following equations (a) and (b), respectively.
x11 = 2L · (1-E1) ... (a), x12 = 2L · E2 ... (b)
The distance x1 from the power transmission end to the failure point is obtained as the average value of the calculated value x11 and the calculated value x12.
The distance x2 from the end point to the failure point is calculated separately by the following equations (c) and (d), respectively.
x21 = L · (2E1-1) ... (c), x22 = L · (1-2E2) ... (d)
It is characterized in that the distance x2 from the end point to the failure point is obtained as an average value of the calculated value x21 and the calculated value x22.

The fault point distance detecting device according to the invention of claim 3 is
The invention according to claim 1 or 2, wherein the distance x1 from the power transmission end to the failure point is a calculated value x12, and the distance x2 from the end to the failure point is a calculated value x22.

The failure point distance detecting device according to the invention of claim 4 is
When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the power transmission passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the termination of the failure phase and the short-circuit device, and passes through the healthy phase. A healthy phase current detector that detects the healthy phase current I2 flowing through the second ground fault circuit that passes through the confluence on the end side and returns to the negative terminal of the DC power supply unit.
A first ground fault circuit that passes from the positive terminal of the DC power supply device, passes through the failure point, branches at the failure point, passes through the failure phase, passes through the confluence point on the transmission end side, and returns to the minus terminal of the DC power supply device. The total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The healthy phase current detector is an ammeter whose internal resistance is smaller than the resistance value of the power line.
When the healthy phase current I2 / the total current I3 is the second index value E2 and the distance of the power line from the transmission end to the end is L.
The distance x1 from the power transmission end to the failure point is calculated by the following equation (b).
x12 = 2L ・ E2 ... (b)
The distance x1 from the power transmission end to the failure point is obtained as a calculated value x12.
The distance x2 from the end point to the failure point is calculated by the following equation (d).
x22 = L · (1-2E2) ... (d)
It is characterized in that the distance x2 from the end point to the failure point is obtained as a calculated value x22.

The fault point distance detecting device according to the invention of claim 5 is
When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the DC power supply device passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the failure phase, and passes through the confluence point on the transmission end side. The faulty phase current I1 flowing through the first ground fault circuit returning to the negative terminal of the current and the positive terminal of the DC power supply device pass through the fault point, branch at the fault point, and pass through the termination of the fault phase and the short circuit device to be sound. A differential current detector that detects the differential current I12 from the healthy phase current I2 that flows through the second ground fault circuit that passes through the confluence point on the transmission end side via the phase and returns to the negative terminal of the DC power supply device.
A total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The differential current detector is a differential magnetic field detection type that detects the difference current I12 between the faulty phase current I1 and the healthy phase current I2 by inputting the faulty phase current I1 and the healthy phase current I2 in opposite directions. Current detector,
When the difference current I12 / the total current I3 is the third index value E3 and the distance of the power line from the transmission end to the end is L.
The distance x1 from the power transmission end to the failure point is calculated by the following equation (e).
x1 = L · (1-E3) ... (e)
The distance x2 from the end point to the failure point is calculated by the following equation (f).
x2 = L ・ E3 ... (f)
It is characterized in that the distance x1 from the power transmission end to the failure point and the distance x2 from the end to the failure point are obtained.

The failure point distance detecting device according to the invention of claim 6 is the failure point distance detecting device according to claims 1 to 4, from the transmission end to the failure point obtained in claims 1 to 4. When the sum (x1 + x2) of the distance x1 and the distance x2 from the end to the failure point is greater than the distance L of the power line from the transmission end 11 to the end 12 by α1, the calculated value x1 and the calculated value x2 are calculated by α1 / 2. The distance x1 from the transmission end 11 to the failure point G and the distance x2 from the end 12 to the failure point are obtained by subtracting from the above, while the distance x1 from the transmission end 11 to the failure point G and the distance from the end 12 to the failure point G. When the sum (x1 + x2) with the distance x2 is smaller by α2 than the distance L of the power line from the transmission end 11 to the end 12, add only α2 / 2 to the calculated value x1 and the calculated value x2, and the failure point G from the transmission end 11. It is characterized in that the distance x1 to and the distance x2 from the end point 12 to the failure point G are obtained.

According to the invention of claim 1, the first index value is used by using the fault phase current I1 and the full phase current I2 detected by the fault phase current detector or the healthy phase current detector whose internal resistance is smaller than the resistance value of the power line. E1, the second index value E2, the distance L from the power transmission end to the end, and the calculation formulas (a) to (d). Therefore, the accuracy of the distance to the failure point is improved, and the distance to the failure point can be obtained inexpensively with a simple configuration. Further, the distance x1 from the transmission end of the power line to the failure point is obtained as the calculated value x11 and the calculated value x12 by the two separate calculation formulas (a) and (b), and the two separate calculation formulas (c) are obtained. ) And (d), the distance x2 from the end of the power line to the failure point is calculated as the calculated value x21 and the calculated value x22, and the distance x1 from the transmission end to the failure point is the average value of the calculated value x11 and the calculated value x12. Since the distance x2 from the end to the failure point is obtained as the average value of the calculated value x21 and the calculated value x22, the accuracy of the distance to the failure point is further improved.

According to the invention of claim 2, since the faulty phase current I1 and the healthy phase current I2 can be detected by the combined current detector whose internal resistance is smaller than the resistance value of the power line , the current detector can be used as the total current detector and the combined current. The current detector can be often saved and the device can be simplified by using the two together with the detector, and the same effect as that of claim 1 can be obtained.

According to the invention of claim 3, in the invention of claim 1 or 2, the healthy phase current I2 detected by the healthy phase current detector which is not easily affected by the detection error is used from the transmission end to the failure point. Since the distance x1 is obtained as the calculated value x12 and the distance x2 from the end to the failure point is obtained as the calculated value x22, if the healthy phase current detector or the failure phase current detector has a detection error, the failure point is more accurate. Can calculate the distance to.

According to the invention of claim 4, the distance from the transmission end to the failure point using the healthy phase current I2 detected by the healthy phase current detector without providing the faulty phase current detector that is easily affected by the detection error. Since x1 is obtained as the calculated value x12 and the distance x2 from the end to the failure point is obtained as the calculated value x22, the current detector can be saved. In addition, the distance to the failure point can be calculated with the same accuracy as in claim 3.

According to the invention of claim 5, since the differential current detector is a differential magnetic field detection type current detector and the internal resistance is practically zero, the faulty phase current I1 and the healthy phase detected by the differential current detector The difference current I12 from the current I2 can be detected with high accuracy. Since the distance to the failure point is calculated using the difference current I12 having high detection accuracy between the failure phase current I1 and the healthy phase current I2, the distance to the failure point can be calculated accurately.

According to the invention of claim 6, in the inventions of claims 1 to 4, the sum of the calculated value of the distance x1 from the transmission end to the failure point and the calculated value of the distance x2 from the end to the failure point is the transmission end. If there is an excess or deficiency with respect to the distance L of the power line from the transmission end to the end, the sum of the distance x1 from the transmission end to the failure point and the distance x2 from the end to the failure point is the distance L of the power line from the transmission end to the end. Since the correction calculation is performed so as to be, the accuracy of the distance to the failure point is improved.

FIG. 6 is a block diagram of an example in which the failure point distance detection device according to the first embodiment of the present invention is applied to a three-phase three-wire power circuit. FIG. 3 is a block diagram of another example in which the failure point distance detection device according to the first embodiment of the present invention is applied to a three-phase three-wire power circuit. FIG. 6 is a block diagram of an example in which the failure point distance detection device according to the first embodiment of the present invention is applied to a three-phase four-wire power circuit. The block diagram of an example which applied the fault point distance detection apparatus which concerns on 1st Embodiment of this invention to a single-phase two-wire type or DC two-wire type power circuit. FIG. 6 is a block diagram of an example in which the failure point distance detection device according to the second embodiment of the present invention is applied to a three-phase three-wire power circuit. FIG. 3 is a block diagram of another example in which the failure point distance detection device according to the second embodiment of the present invention is applied to a three-phase three-wire power circuit. FIG. 6 is a block diagram of an example in which the failure point distance detection device according to the third embodiment of the present invention is applied to a single-phase two-wire power circuit. FIG. 3 is a block diagram of another example in which the failure point distance detection device according to the third embodiment of the present invention is applied to a single-phase two-wire power circuit. FIG. 3 is a block diagram of another example in which the failure point distance detection device according to the third embodiment of the present invention is applied to a single-phase two-wire power circuit. FIG. 6 is a block diagram of an example in which the failure point distance detection device according to the fourth embodiment of the present invention is applied to a three-phase three-wire power circuit. FIG. 3 is a block diagram of another example in which the failure point distance detection device according to the fourth embodiment of the present invention is applied to a three-phase three-wire power circuit. The circuit diagram of the matching test circuit which performs the test adjustment and accuracy matching of the total current detector and the difference current detector in the 4th Embodiment of this invention. A circuit diagram of a three-phase three-wire power circuit in which a faulty phase is obtained by individually measuring the insulation resistance for each of the three phases with an insulation resistance tester.

Hereinafter, embodiments of the present invention will be described. The fault point distance detecting device according to the embodiment of the present invention detects the position of the fault point G of the fault phase after determining which phase of the power circuit is faulty with an insulation resistance tester. be.
<First Embodiment>
FIG. 1 is a configuration diagram of an example in which the failure point distance detection device according to the first embodiment of the present invention is applied to a three-phase three-wire power circuit. With respect to the circuit diagram of the three-phase three-wire power circuit shown in FIG. 13, the same elements are designated by the same reference numerals and overlapping description will be omitted.

The fault point distance detection device according to the first embodiment of the present invention includes a short circuit device 17, a DC power supply device 15, a fault phase current detector 18, a healthy phase current detector 19, a total current detector 20, and a total current detector 20. It is composed of a distance calculation device 21.

The short-circuit device 17 is in a state where the three-phase power circuit is stopped, that is, in a state where the application of the three-phase alternating current to the RST phase power line is stopped, and at the end 12 of the three-phase power line, the faulty phase of the three-phase power lines. And the termination of the healthy phase of any one of the two healthy phases is short-circuited. FIG. 1 shows a case where the faulty phase is the T phase and the healthy phase is the R phase and the S phase, and the faulty phase T phase and the healthy phase S phase are short-circuited by the short-circuit device 17. The reason why the short-circuit device 17 short-circuits the T phase, which is the faulty phase, and the S phase, which is the healthy phase, is to form a DC circuit for supplying a DC current from the DC power supply device 15 to detect the fault point position. be.

In the DC power supply device 15, the T phase of the faulty phase and the S phase of the healthy phase are short-circuited by the short-circuit device 17 at the terminal 12 of the three-phase power line, and the T phase of the faulty phase is short-circuited at the transmission end 11 of the three-phase power line. And a negative DC voltage is applied to the S phase of the healthy phase. That is, the positive terminal of the DC power supply device 15 is grounded, and a DC voltage is applied from the DC power supply device 15 to the T phase of the faulty phase and the S phase of the healthy phase via the ground and the fault point G. In this case, if there is a branch power circuit in the middle of the three-phase power circuit, the end of the branch power circuit is opened.

By applying the DC voltage of the DC power supply device 15 to the T phase of the failure phase, the failure current Ig flows from the positive terminal of the DC power supply device 15 via the failure resistance Rg of the ground and the failure point G, and the failure current Ig fails. It branches at the point G and splits into a faulty phase current I1 passing through the T phase of the faulty phase and a healthy phase current I2 passing through the S phase of the healthy phase. The faulty phase current I1 passing through the T phase of the faulty phase returns to the negative terminal of the DC power supply device 15 via the confluence point B on the transmission end 11 side. On the other hand, the healthy phase current I2 passing through the S phase of the healthy phase passes through the S phase of the healthy phase via the termination 12 of the T phase of the faulty phase and the short-circuit device 17, and passes through the confluence point B on the transmission end 11 side. Return to the negative terminal of the DC power supply device 15.

That is, the positive terminal of the DC power supply device 15 passes through the ground and the failure resistance Rg of the failure point G, passes through the T phase of the failure phase and the confluence point B on the transmission end 11 side, and returns to the negative terminal of the DC power supply device 15. 1 A ground fault circuit is formed, and the positive terminal of the DC power supply device 15 passes through the ground and the failure resistance Rg of the failure point G, passes through the T-phase termination 12 of the failure phase, and the short-circuit device 17, and then the S of the healthy phase. A second ground fault circuit is formed that passes through the phase, passes through the confluence point B on the transmission end 11 side, and returns to the negative terminal of the DC power supply device 15.

The faulty phase current detector 18 provided on the power transmission end side detects the faulty phase current I1 flowing in the first ground fault circuit, and the healthy phase current detector 19 provided on the power transmission end side detects the second ground fault. It detects the healthy phase current I2 flowing in the circuit. Further, the total current detector 20 provided on the transmission end side detects the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2.

Here, an ammeter having a small internal resistance is used as the faulty phase current detector 18 and the healthy phase current detector 19. This is because the faulty phase current detector 18 is connected to the first diversion circuit formed between the fault point G of the first ground fault circuit and the confluence point B on the transmission end 11 side, and the healthy phase current detector 19 is The first diversion circuit and the second diversion circuit formed in parallel are connected to the second diversion circuit formed between the failure point G of the second ground fault circuit and the confluence point B on the transmission end 11 side. This is because the diversion current that flows is affected by the magnitude of the internal resistance of the faulty phase current detector 18 and the healthy phase current detector 19.

The resistance of the power line of the power circuit forming the first shunt circuit and the second shunt circuit is usually 0.05 [mΩ / m] to several [mΩ / m], but the internal resistance of the analog mA ammeter is Compared to that, it is considerably larger and is several tens of Ω. Further, since the first shunt circuit and the second shunt circuit are formed in parallel, the first shunt circuit and the second shunt circuit depend on the magnitude of the internal resistance of the faulty phase current detector 18 and the healthy phase current detector 19. The shunt ratio of the current flowing through is affected.

That is, the total current I3 is divided into the faulty phase current I1 flowing in the first diversion circuit and the healthy phase current I2 flowing in the second diversion circuit, but the internal resistance of the faulty phase current detector 18 and the healthy phase current detector 19 If the diversion ratio of the current flowing in the first diversion circuit or the second diversion circuit is affected by the magnitude, the current flowing in the first diversion circuit and the second diversion circuit cannot be detected accurately.

Therefore, in the first embodiment of the present invention, the fault phase current detector 18 and the healthy phase current detector 19 are current detectors having a small internal resistance, for example, a digital current detector and an operational amplifier (arithmetic amplifier) type current detector. , A magnetic field detection type current detector, etc. is used. Also in the second embodiment, the third embodiment, and the third embodiment described below, a current detector having a small internal resistance is used as the current detector connected to the first diversion circuit and the second diversion circuit. Since the total current detector 20 is not connected to the divergence circuit, it does not affect the divergence ratio. Therefore, it is not necessary to adopt a current detector having a small internal resistance.

Next, the distance calculation device 21 is composed of, for example, a general computer, a storage device in which a software program is installed, a calculation control device for calculating a software program, an input device for inputting information to the calculation control device, and a calculation control device. It has an output device that outputs the calculation result of. The distance calculation device 21 inputs the faulty phase current I1 detected by the faulty phase current detector 18, the healthy phase current I2 detected by the healthy phase current detector 19, and the total current I3 detected by the total current detector 20. Then, based on these currents, the distance x1 from the transmission end 11 of the three-phase power line to the failure point G and the distance x2 from the end 12 of the three-phase power line to the failure point are calculated.

The relationship between the faulty phase current I1 detected by the faulty phase current detector 18, the healthy phase current I2 detected by the healthy phase current detector 19, and the total current I3 detected by the total current detector 20 is as follows (1). ).

I3 = I1 + I2 ... (1)
Further, the DC resistance Rt of the T-phase power line of the fault phase is the sum of the DC resistance Rt1 from the transmission end 11 of the three-phase power line to the fault point G and the DC resistance Rt2 from the terminal 12 to the fault point G. The following equation (2) holds.

Rt = Rt1 + Rt2 ... (2)
Assuming that the distance of the power line from the power transmission end 11 to the end point 12 is L, the distance from the power transmission end 11 to the failure point G is x1, and the distance from the end point 12 to the failure point G is x2, the following equation (3) holds.

L = x1 + x2 ... (3)
Further, assuming that the unit length resistance value of the RST phase power line is r, the DC resistance Rr of the R phase power line, the DC resistance Rs of the S phase power line, and the DC resistance Rt of the T phase power line are usually the same values. , RST phase DC resistances Rr, Rs, Rt of the power line are represented by the following equation (4). Further, the DC resistance Rt1 from the transmission end 11 of the three-phase power line to the failure point G and the DC resistance Rt2 from the terminal 12 to the failure point G are represented by the following equations (5) and (6).

Rr, Rs, Rt = r · L ... (4)
Rt1 = r · x1 ... (5)
Rt2 = r · x2 ... (6)
Since the potential difference between the failure point G and the confluence point B in the first ground fault circuit and the second ground fault circuit is equal, the following equation (7) holds.

I1 ・ Rt1 = I2 ・ (Rt2 + Rs)… (7)
From the equation (7), the faulty phase current I1 is represented by the following equation (8), and the healthy phase current I2 is represented by the following equation (9).

I1 = {(Rt2 + Rs) / Rt1} ・ I2 ... (8)
I2 = {Rt1 / (Rt2 + Rs)} ・ I1 ... (9)
By substituting the healthy phase current I2 in the equation (9) into the equation (1) to obtain the relational expression between the faulty phase current I1 and the total current I3, the following equation (10) is obtained.

I1 = {(Rt2 + Rs) / (Rt1 + Rt2 + Rs)} · I3 ... (10)
By substituting the faulty phase current I1 of the equation (8) into the equation (1) to obtain the relational expression between the healthy phase current I2 and the total current I3, the following equation (11) is obtained.

I2 = {Rt1 / (Rt1 + Rt2 + Rs)} · I3 ... (11)
Next, using these equations (1) to (11), how to calculate the distance x1 from the power transmission end 11 of the power circuit to the failure point G and the distance x2 from the end 12 of the power circuit to the failure point G. Will be explained.

The distance x1 from the power transmission end 11 to the failure point G has two cases, one is obtained from the equation (10) and the other is obtained from the equation (11), and these two ways are calculated separately.

When the distance x1 from the power transmission end 11 to the failure point G is obtained from the equation (10), it is obtained as follows. First, by substituting the equations (4), (5), and (6) into the equation (10), the equation (12) is obtained.

I1 = {(r ・ x2 + r ・ L) / (r ・ x1 + r ・ x2 + r ・ L)} ・ I3
= {(X2 + L) / (x1 + x2 + L)} ・ I3 ... (12)
Then, by substituting x2 = L−x1 obtained from the equation (3) into x2 of the equation (12), the equation (13) is obtained.

I1 = {(2L-x1) / 2L} ・ I3 ... (13)
Now, let I1 / I3 be the first index value E1. Then, by substituting (I1 / I3) = E1 into the equation (13) and solving for the distance x1, the equation (14) is obtained. The distance x1 to the failure point G obtained by the equation (14) is set as the calculated value x11.

x1 = 2L · (1-E1) = x11 ... (14)
Further, when the distance x1 from the power transmission end 11 to the failure point G is obtained from the equation (11), it is obtained as follows. First, the equation (4), the equation (5), and the equation (6) are substituted into the equation (11) to obtain the equation (15).

I2 = {r ・ x1 / (r ・ x1 + r ・ x2 + r ・ L)} ・ I3
= {X1 / (x1 + x2 + L)} ・ I3 ... (15)
Then, by substituting x2 = L−x1 obtained from the equation (3) into x2 of the equation (15), the equation (16) is obtained.

I2 = {x1 / 2L} ・ I3 ... (16)
Now, let I2 / I3 be the second index value E2. Then, by substituting (I2 / I3) = E2 into the equation (16) and solving for the distance x1, the equation (17) is obtained. The distance x1 to the failure point G obtained by the equation (17) is set as the calculated value x12.

x1 = 2L · E2 = x12 ... (17)
As a result, the calculated value x11 is represented by the following formula (18), and the calculated value x12 is represented by the following formula (19).

x11 = 2L ・ (1-E1)… (18)
x12 = 2L ・ E2 ... (19)
The distance x1 from the power transmission end 11 of the power line to the failure point G is obtained as the average value of the calculated value x11 obtained by the equation (18) and the calculated value x12 obtained by the equation (19), and the position of the failure point G is obtained. Ask for.

Next, the distance x2 from the end 12 of the power circuit to the failure point G can be obtained from the equation (10) and (11) in the same manner as when the distance x1 from the power transmission end 11 of the power circuit to the failure point G is obtained. ) There are two ways to calculate from the formula, and these two ways are calculated separately.

When the distance x2 from the terminal 12 to the failure point G is obtained from the equation (10), it is obtained as follows. First, the equation (4), the equation (5), and the equation (6) are substituted into the equation (10) to obtain the equation (12). Until the equation (12) is obtained, it is the same as the case where the distance x1 from the power transmission end 11 to the failure point G is obtained.

Then, x1 = L−x2 obtained from the equation (3) is substituted into x1 of the equation (12). This point is different. By substituting x1 = L−x2 for x1 of the equation (12), the equation (20) is obtained.

I1 = {(L + x2) / 2L} ・ I3 ... (20)
Since the first index value E1 is represented by I1 / I3, the equation (21) can be obtained by solving the equation (20) with respect to the distance x2. The distance x2 to the failure point G obtained by the equation (21) is set as the calculated value x21.

x2 = L · (2E1-1) = x21 ... (21)
Next, when the distance x2 from the terminal 12 to the failure point G is obtained from the equation (11), it is obtained as follows. First, the equation (4), the equation (5), and the equation (6) are substituted into the equation (11) to obtain the equation (15). Until the equation (15) is obtained, it is the same as the case where the distance x1 from the power transmission end 11 to the failure point G is obtained.

Then, x1 = L−x2 obtained from the equation (3) is substituted into x1 of the equation (15). This point is different.
Substituting x1 = L−x2 for x1 in equation (15) gives equation (22).

I2 = {(L-x2) / 2L} · I3 ... (22)
Since the second index value E2 is represented by I2 / I3, the equation (23) can be obtained by solving the equation (22) for the distance x2. The distance x2 to the failure point G obtained by the equation (23) is set as the calculated value x22.

x2 = L · (1-2E2) = x22 ... (23)
As a result, the calculated value x21 is represented by the following formula (24), and the calculated value x22 is represented by the following formula (25).

x21 = L · (2E1-1) ... (24)
x22 = L · (1-2E2) ... (25)
The distance x2 from the end 12 of the power line to the failure point G is obtained as the average value of the calculated value x21 obtained by the equation (24) and the calculated value x22 obtained by the equation (25), and the position of the failure point G is determined. Ask.

In the above description, when the faulty phase is the T phase and the healthy phase is the R phase and the S phase, the fault point is from the transmission end 11 of the three-phase power line using the T phase of the fault phase and the S phase of the healthy phase. The case of calculating the distance x1 to G and the distance x2 from the end 12 of the three-phase power line to the failure point G has been described, but as shown in FIG. 2, the R phase of the healthy phase is used instead of the S phase of the healthy phase. It may be used to calculate the distance x1 and the distance x2 using the T phase of the faulty phase and the R phase of the healthy phase.

Furthermore, the distances x1 and x2 calculated using the T phase of the faulty phase and the R phase of the healthy phase, and the distances x1 and x2 calculated using the T phase of the faulty phase and the S phase of the healthy phase are calculated, respectively. , You may try to take the average value of these. Since the distances x1 and x2 are calculated for not only one healthy phase but also two healthy phases, the DC resistance Rr of the R phase power line, the DC resistance Rs of the S phase power line, and the DC resistance Rt of the T phase power line. If there is a variation in the DC resistance value of, the variation can be corrected.

Further, in the above description, the case where it is applied to a three-phase three-wire system power circuit has been described, but it can also be applied to a three-phase four-wire system power circuit. The three-phase four-wire power circuit is a power circuit in which one neutral wire having the same specifications as the RST phase power line is added in addition to the three RST phase power lines. FIG. 3 is a configuration diagram of an example in which the failure point distance detection device according to the first embodiment of the present invention is applied to a three-phase four-wire power circuit. In FIG. 3, when the faulty phase is the T phase and the healthy phase is the R phase and the S phase, the fault point is from the transmission end 11 of the three-phase power line using the T phase of the fault phase and the N phase of the neutral line. The distance x1 to G and the distance x2 from the end 12 of the three-phase power line to the failure point G are calculated. That is, the N phase of the neutral line is used instead of the R phase or the S phase which is the healthy phase.

Of course, even in a three-phase four-wire power circuit, as in the case of a three-phase three-wire power circuit, one of the faulty phase and the healthy phase of the three-phase power lines can be used. It may be used to calculate the distance x1 from the transmission end 11 of the three-phase power line to the failure point G and the distance x2 from the end 12 of the three-phase power line to the failure point G.

In this way, when the power circuit is a three-phase four-wire system, with the three-phase four-wire system power circuit stopped, the faulty phase of the three-phase power lines and the healthy phase and the neutral line are included. Short-circuit the end 12 of any one phase, calculate the distance x1 from the transmission end 11 of the three-phase power line to the failure point G and the distance x2 from the end 12 of the three-phase power line to the failure point G, and fail in the failure phase. Find the position of point G.

Since the three-phase four-wire power circuit is a power circuit in which one neutral wire having the same specifications as the RST phase power wire is added, the distance to the failure point G calculated using the neutral wire x1 and x2. , The average value of the distances x1 and x2 to the failure point G calculated using the R phase and the S phase, which are healthy phases, may be taken.

Furthermore, it can be applied to a single-phase two-wire system or a DC two-wire system. FIG. 4 is a configuration diagram of an example in which the failure point distance detection device according to the first embodiment of the present invention is applied to a single-phase two-wire system or a DC two-wire system power circuit. For convenience, the single-phase two-wire or DC two-wire power line is shown as the ST phase, the faulty phase is shown as the T phase, and the healthy phase is shown as the S phase. As in the case of a three-phase three-wire system or a three-phase four-wire system power circuit, the termination of the faulty phase and the healthy phase is short-circuited with the single-phase two-wire system or DC two-wire system power circuit stopped. Then, the distance x1 from the power transmission end 11 to the failure point G and the distance x2 from the terminal 12 to the failure point G are obtained, and the position of the failure point G is obtained.

When applied to a single-phase three-wire power circuit, the single-phase three-wire power circuit is a power circuit in which one neutral wire having the same specifications as these is added in addition to the two power lines. Therefore, it is a power circuit in which one neutral wire is added to the single-phase two-wire power circuit shown in FIG . Therefore, using the T phase of the faulty phase and the N phase of the neutral line (or the S phase which is the healthy phase), the distance x1 from the transmission end 11 of the single-phase power line to the fault point G and the end 12 of the three-phase power line. The distance x2 from the fault point G to the fault point G is calculated. That is, with the single-phase three-wire power circuit stopped, the faulty phase and one of the healthy phase and the neutral wire are used to reach the fault point G from the transmission end 11 of the single-phase power line. The distance x1 and the distance x2 from the end 12 of the three-phase power line to the failure point G are calculated.

Since the single-phase three-wire power circuit is a power circuit in which one neutral wire having the same specifications as the two power wires is added, the distance to the failure point G calculated using the neutral wire x1 and x2. , The average value of the distances x1 and x2 to the failure point G calculated using the S phase, which is a healthy phase, may be taken.

According to the first embodiment, the DC power supply device 15 is used at the transmission end 11 of a power circuit such as a three-phase three-wire system, a three-phase four-wire system, a single-phase two-wire system, a DC two-wire system, or a single-phase three-wire system. The fault phase current I1 flowing through the first ground fault circuit that passes through the fault point G, branches at the fault point G, passes through the confluence B on the transmission end 11 side, and returns to the DC power supply device 15, is the fault phase current. It is detected by the detector 18, passes through the failure point G from the DC power supply device 15, branches at the failure point G, passes through the termination 12 of the failure phase and the short circuit device 17, passes through the healthy phase, and passes through the confluence point B on the transmission end 11 side. The healthy phase current I2 flowing through the second ground fault circuit returning to the DC power supply device 15 is detected by the healthy phase current detector 19, and the total current I3 of the sum of the faulty phase current I1 and the healthy phase current I2 is the total current detector. Detected at 20, the first index value E1 (failure phase current I1 / total current I3) and the second index value E2 (healthy phase current I2 / total current I3) are obtained, and the first index value E1 and the second index value E2 are obtained. , The distance x1 from the transmission end 11 of the power line to the failure point G and the distance x2 from the end 12 of the power line to the failure point are calculated by the calculation formula represented by the distance L of the power line from the transmission end 11 to the end 12. The distance to the failure point G can be obtained inexpensively with a simple configuration.

Further, the distance x1 from the transmission end of the power line to the failure point is obtained as the calculated value x11 and the calculated value x12 by the two separate calculation formulas (18) and (19) , and the two separate calculation formulas (24 ) are obtained. ) And (25) , the distance x2 from the end of the power line to the failure point is calculated as the calculated value x21 and the calculated value x22, and the distance x1 from the transmission end to the failure point is the average value of the calculated value x11 and the calculated value x12. Since the distance x2 from the end to the failure point is obtained as the average value of the calculated value x21 and the calculated value x22, the accuracy of the distance to the failure point is improved.

In this way, when a deterioration in insulation performance or a ground fault is detected in the power line of the power circuit, the position of the failure point G can be easily identified, so that the response time and personnel for the failure can be significantly reduced. It will be possible. Since the position of the failure point G can be specified, partial maintenance can be performed and the wire material and maintenance time can be significantly reduced as compared with removing and replacing the power line in which the insulation failure has occurred.

In addition, by combining it with a technology that can constantly detect the fault phase in which the insulation performance of the power circuit has deteriorated, the ground insulation resistance value, and the ground capacitance (Japanese Patent Application No. 2019-141054 previously filed by the present applicant). It is possible to maintain a high level of insulation performance of power circuits including load equipment. Furthermore, if the insulation performance of the power circuit deteriorates or a ground fault occurs, the position can be identified within a short time, and the power circuit can be temporarily restored, the power supply can be restored, and the equipment can be restarted, and the power supply is stopped. It helps to minimize the economic loss associated with the equipment, and it also enables the subsequent planned repair and maintenance, which helps to improve the safety and productivity of the equipment.
<Second Embodiment>
Next, a second embodiment of the present invention will be described. FIG. 5 is a configuration diagram of an example in which the failure point distance detection device according to the second embodiment of the present invention is applied to a three-phase three-wire power circuit. An example of this second embodiment is provided with a switching device 22 for switching between the first ground fault circuit and the second ground fault circuit between the power transmission end 11 and the confluence point B with respect to the first embodiment shown in FIG. In addition, the combined current detector 23 is provided in place of the faulty phase current detector 18 and the healthy phase current detector 19. In FIG. 5, as in the case of FIG. 1, the faulty phase is the T phase, the healthy phase is the R phase and the S phase, and the faulty phase T phase and the healthy phase S phase are short-circuited by the short-circuit device 17. Shows the case. The same elements as those in FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted. Further, as described in the first embodiment, since the combined current detector 23 is connected to the first diversion circuit and the second diversion circuit, a current detector having a small internal resistance is used.

In FIGS. 5A and 5B, a switching device 22 is provided at the power transmission end 11 of the three-phase power line. The switching device 22 is a first ground fault circuit that passes from the DC power supply device 15 through the failure point G, branches at the failure point G, passes through the failure phase, passes through the confluence point B on the transmission end 11 side, and returns to the DC power supply device 15. , From the DC power supply device 15, passes through the failure point G1, branches at the failure point G1, passes through the failure phase termination 12 and the short circuit device 17, passes through the healthy phase, passes through the confluence point B on the transmission end 11 side, and reaches the DC power supply device 15. The return second ground fault circuit is switched between the transmission end 11 and the confluence point B.

In FIG. 5A, the combined current detector 23 is connected to the first ground fault circuit by switching the switching device 22. That is, in this state, the combined current detector 23 detects the fault phase current I1 flowing in the first ground fault circuit. The total current detector 20 detects the sum of the faulty phase current I1 flowing in the first ground fault circuit and the healthy phase current I2 flowing in the second ground fault circuit as the total current I3.

FIG. 5B shows a case where the combined current detector 23 is connected to the second ground fault circuit by switching the switching device 22. That is, in this state, the combined current detector 23 detects the healthy phase current I2 flowing in the second ground fault circuit. The total current detector 20 detects the sum of the faulty phase current I1 flowing in the first ground fault circuit and the healthy phase current I2 flowing in the second ground fault circuit as the total current I3.

In this way, by switching between the first ground fault circuit and the second ground fault circuit in the switching device 22, the combined current detector 23 flows to the first ground fault circuit when connected to the first ground fault circuit. The faulty phase current I1 is detected, and when connected to the second ground fault circuit, the healthy phase current I2 flowing through the second ground fault circuit is detected.

Then, as in the first embodiment, the first index value E1 (failure phase current I1 / total current I3) and the second index value E2 are based on the fault phase current I1, the healthy phase current I2, and the total current I3. (Healthy phase current I2 / total current I3) is obtained, and is expressed by the first index value E1, the second index value E2, and the distance L of the power line from the power transmission end 11 to the terminal 12, from the power transmission end 11 of the power line. The distance x1 to the failure point G and the distance x2 from the end 12 of the power line to the failure point are obtained.

In the above description, when the faulty phase is the T phase and the healthy phase is the R phase and the S phase, the fault point is from the transmission end 11 of the three-phase power line using the T phase of the fault phase and the S phase of the healthy phase. The case of calculating the distance x1 to G and the distance x2 from the end 12 of the three-phase power line to the failure point G has been described. As shown in FIG. 6, the R phase of the healthy phase is used instead of the S phase of the healthy phase. It may be used to calculate the distance x1 and the distance x2 using the T phase of the faulty phase and the R phase of the healthy phase.

In FIG. 6A, the combined current detector 23 is connected to the first ground fault circuit by switching the switching device 22, and the combined current detector 23 detects the fault phase current I1 flowing in the first ground fault circuit. On the other hand, in FIG. 6B, the combined current detector 23 is connected to the second ground fault circuit by switching the switching device 22.

Further, the average values of the distances x1 and x2 calculated using the T phase of the faulty phase and the R phase of the healthy phase and the distances x1 and x2 calculated using the T phase of the faulty phase and the S phase of the healthy phase are calculated. You may try to take it. Since the distances x1 and x2 are calculated for not only one healthy phase but also two healthy phases, the DC resistance Rr of the R phase power line, the DC resistance Rs of the S phase power line, and the DC resistance Rt of the T phase power line. If there is a variation in the DC resistance value of, the variation can be corrected.

Further, in the above description, the case where it is applied to a three-phase three-wire power circuit has been described, but a three-phase four-wire power circuit, a single-phase two-wire power circuit, and a single-phase three-wire power circuit have been described. It can also be applied to a DC 2-wire power circuit. The application to a three-phase four-wire power circuit, a single-phase two-wire power circuit, a single-phase three-wire power circuit, and a DC two-wire power circuit is the same as in the case of the first embodiment. Is omitted.

According to the second embodiment, since the combined current detector 23 can also use the faulty phase current detector 18 and the healthy phase current detector 19 of the first embodiment shown in FIG. 1, one current. You can save the detector. Further, it is possible to eliminate the individual error between the faulty phase current detector 18 and the healthy phase current detector 19.
<Third Embodiment>
Next, a third embodiment of the present invention will be described. In the third embodiment, with respect to the first embodiment and the second embodiment, the distance x1 from the transmission end 11 to the failure point G is set as the average value of the calculated value x11 and the calculated value x12, and from the terminal 12 to the failure point G. Instead of finding the distance x2 as the average value of the calculated value x21 and the calculated value x22, the distance x1 from the transmission end to the failure point is set as the calculated value x12, and the distance x2 from the end point 12 to the failure point G is the calculated value. It is calculated as x22.

FIG. 7 is a configuration diagram of an example in which the failure point distance detection device according to the third embodiment of the present invention is applied to a single-phase two-wire power circuit. FIG. 7 shows an example in which the failure point distance detection device according to the third embodiment of the present invention is applied to the single-phase two-wire power circuit shown in FIG. 4 in the first embodiment.

In FIG. 7, the detection error of the faulty phase current detector 18 is ε1%, the detection error of the healthy phase current detector 19 is ε2%, and the detection error of the total current detector 20 is 0%. Further, the faulty phase current detected when there is no detection error in the faulty phase current detector 18 is I1, and the healthy phase current detected when there is no detection error in the healthy phase current detector 19 is I2.

First, the faulty phase current I1a including the detection error detected by the faulty phase current detector 18 is represented by the following equation (26) because the detection error of the faulty phase current detector 18 is ε1%.

I1a = I1 · (1 + ε1 / 100) ... (26)
Substituting E1 = I1 / I3 for E1 in Eq. (14) and further substituting I1a in Eq. (26) for I1, the calculated value x11a of the distance x1a including the error is shown by Eq. (27) below. Is done.

x11a = 2L · {1- (I1 · (1 + ε1 / 100) / I3)} ... (27)
The error portion Δx11 of the calculated value x11a is expressed by the following equation (28).

Δx11 = 2L · (I1 · (ε1 / 100) / I3) ... (28)
Since I1 + 12 = I3 from the equation (1), I1 ≦ I3, and as can be seen from the equation (28), the error component Δx11 becomes maximum when I1 = I3, that is, the failure point G is the transmission end 11. The maximum value of Δx11, Δx11max, is Δx11max = 2L · (ε1 / 100). On the other hand, the error amount Δx11 becomes the minimum when I1 = I3 / 2, that is, when the failure point G is the terminal 12, and the minimum value Δx11min of Δx11 is Δx11min = L · (ε1 / 100). be. The error amount Δx11 of the distance x calculated by using the faulty phase current I1a detected by the faulty phase current detector 18 is summarized as follows.

(A1) The maximum value of the error amount Δx11 is 2L · (ε1 / 100).
When the failure point G is the power transmission end 11 (when I1 = I3),
(A2) The minimum value of the error amount Δx11 is L · (ε1 / 100).
When the failure point G is the terminal 12 (when I1 = I3 / 2)
Next, the healthy phase current I2a including the detection error detected by the healthy phase current detector 19 is represented by the following equation (29) because the detection error of the healthy phase current detector 19 is ε2%. ..

I2a = I2 ・ (1 + ε2 / 100)… (29)
Substituting E2 = I2 / I3 for E2 in Eq. (12) and further substituting I2a in Eq. (29) for I2, the calculated value x12a of the distance x1a including the error is shown by Eq. (30) below. Is done.

x12a = 2L ・ (I2 ・ (1 + ε2 / 100) / I3)… (30)
The error amount Δx12 of the calculated value x12a is expressed by the following equation (31).

Δx12 = 2L ・ (I2 ・ (ε2 / 100) / I3)… (31)
Since I1 + 12 = I3 from the equation (1), I2 ≦ I3 / 2, and as can be seen from the equation (31), the error component Δx12 is maximized when I2 = I3 / 2, that is, the failure point G. Is the terminal 12, and the maximum value Δx12max of Δx12 is Δx12max = L · (1 + ε2 / 100).
On the other hand, the error amount Δx12 is minimized when I2 = 0, that is, when the failure point G is the transmission end 11, and the minimum value Δx12min of Δx12 is Δx12min = 0. The error amount Δx12 of the distance x calculated using the healthy phase current I2a detected by the healthy phase current detector 19 can be summarized as follows.

(B1) The maximum value of the error amount Δx12 is L · (1 + ε2 / 100).
When the failure point G is the terminal 12 (when I2 = I3 / 2),
(B2) The minimum value of the error amount Δx12 is 0.
When the failure point G is the power transmission end 11 (when I2 = 0)
From the above, when calculating the distance x1 from the transmission end 11 to the failure point G, when the detection error ε1% of the failure phase current detector 18 and the detection error ε2% of the healthy phase current detector 19 are taken into consideration, It can be seen that the calculated value x12 calculated by the formula (19) has a smaller error than the calculated value x11 calculated by the formula (18).

In the above description, the case where the distance x1 from the transmission end 11 to the failure point G is calculated using the equations (18) and (19) has been described, but the termination is performed by using the equations (24) and (25). In the case of calculating the distance x2 from 12 to the failure point G, the calculation formula is omitted, but similarly, the calculated value x22 calculated by the formula (25) is larger than the calculated value x21 calculated by the formula (24). However, there are few errors.

Therefore, in an example of the failure point distance detecting device according to the third embodiment, the distance x1 from the power transmission end 11 to the failure point G is set as the calculated value x12, and the distance x2 from the end point 12 to the failure point G is obtained as the calculated value x22. ..

FIG. 8 is a configuration diagram of another example in which the failure point distance detection device according to the third embodiment of the present invention is applied to a single-phase two-wire power circuit, and is a configuration diagram of another example, which is the third embodiment of the present invention shown in FIG. A switching device 22 is provided between the power transmission end 11 and the confluence point B for the failure point distance detection device according to the above, and a combined current detector 23 is used in place of the failure phase current detector 18 and the healthy phase current detector 19. It is provided. The same elements as those in FIG. 7 are designated by the same reference numerals, and duplicate description will be omitted.

The switching device 22 is from the first ground fault circuit that passes through the failure point from the DC power supply device, branches at the failure point, passes through the confluence point on the transmission end side via the failure phase, and returns to the DC power supply device, and from the DC power supply device 15. A second ground fault circuit that passes through the failure point G1, branches at the failure point G1, passes through the termination 12 of the failure phase and the short-circuit device 17, passes through the healthy phase, passes through the confluence B on the transmission end 11 side, and returns to the DC power supply device 15. To switch between. When the dual-purpose current detector 23 was switched to the first ground fault circuit by the switching device 22, the faulty phase current I1 flowing through the first ground fault circuit was detected, and the switching device 22 switched to the second ground fault circuit. At this time, the fault phase current I2 flowing through the second ground fault circuit is detected.

In FIG. 8, the detection error of the combined current detector 23 is ε4%, and the detection error of the healthy phase current detector 20 is 0%. Further, the faulty phase current detected when there is no detection error in the combined current detector 23 is I1, and the healthy phase current is I2.

The error portion Δx11 of the distance x calculated by using the fault phase current I1 detected by the combined current detector 23 is calculated and summarized as follows in the same manner as in the case of the example of the fault point distance detection device according to the third embodiment. become.

(C1) The maximum value of the error amount Δx11 is 2L · (ε4 / 100).
When the failure point G is the power transmission end 11 (when I1 = I3),
(C2) The minimum value of the error amount Δx11 is L · (ε4 / 100)
When the failure point G is the terminal 12 (when I1 = I3 / 2)
The error portion Δx12 of the distance x calculated by using the fault phase current I1 detected by the combined current detector 23 is calculated and summarized as follows in the same manner as in the case of the example of the fault point distance detection device according to the third embodiment. become.

(D1) The maximum value of the error amount Δx12 is L · (1 + ε4 / 100).
When the failure point G is the terminal 12 (when I2 = I3 / 2),
(D2) The minimum value of the error amount Δx12 is 0.
When the failure point G is the power transmission end 11 (when I2 = 0)
From the above, when the detection error ε4% of the combined current detector 23 is taken into consideration in the calculation of the distance x1 from the power transmission end 11 to the failure point G, from the calculated value x11 calculated by the equation (18), ( It can be seen that the calculated value x12 calculated by the equation 19) has a smaller error.

In the above description, the case where the distance x1 from the transmission end 11 to the failure point G is calculated using the equations (18) and (19) has been described, but the termination is performed by using the equations (24) and (25). In the case of calculating the distance x2 from 12 to the failure point G, the calculation formula is omitted, but similarly, the calculated value x22 calculated by the formula (25) is larger than the calculated value x21 calculated by the formula (24). However, there are few errors.

Therefore, also in another example of the failure point distance detecting device according to the third embodiment, the distance x1 from the transmission end 11 to the failure point G is set as the calculated value x12, and the distance x2 from the end point 12 to the failure point G is set as the calculated value. Obtained as x22.

FIG. 9 is a configuration diagram of another example in which the failure point distance detecting device according to the third embodiment of the present invention is applied to a single-phase two-wire power circuit. In FIG. 9, the fault phase current detector 18 is deleted from the example of the third embodiment shown in FIG. 7. The same elements as those in FIG. 7 are designated by the same reference numerals, and duplicate description will be omitted.

In the third embodiment, the distance x1 from the power transmission end 11 to the failure point G is set as the calculated value x12, and the distance x2 from the end point 12 to the failure point G is set as the calculated value x22. That is, the calculated value x12 and the calculation by the equations (19) and (25) using the healthy phase current I2 detected by the healthy phase current detector 19 without using the current I1 detected by the faulty phase current detector 18. Since the value x22 is obtained, it is not necessary to provide the fault phase current detector 18. Therefore, the fault phase current detector 18 was deleted from the example of the third embodiment shown in FIG. 7. As a result, the current detector can be reduced.

In the above description of the third embodiment, the case where it is applied to the single-phase two-wire system power circuit has been described, but as in the case of the first embodiment and the second embodiment, the three-phase three-wire system and the three-phase system have been described. It can also be applied to a 4-wire system, a single-phase 3-wire system, and a DC 2-wire system.

According to the third embodiment, the calculated value x12 of the distance x1 from the power transmission end 11 to the failure point G and the distance x2 from the end point 12 to the failure point G are used by using the healthy phase current I2 which is not easily affected by the detection error. Since the calculated value x22 is obtained, the distance to the failure point G can be calculated more accurately.
<Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. In the first to third embodiments, a current detector having a small internal resistance is adopted as the faulty phase current detector 18, the healthy phase current detector 19, and the combined current detector 23. As a result, the current shunt ratio of the current flowing through the first shunt circuit and the second shunt circuit is not affected by the magnitude of the internal resistance of the fault phase current detector 18 and the healthy phase current detector 19, and the fault phase current I1 And the healthy phase current I2 can be detected. However, when a flux gate type current detector is used as a current detector having a small internal resistance, for example, the flux gate type current detector has a limit in detection accuracy, and there is a detection error due to individual differences. Therefore, in the fourth embodiment of the present invention, a differential fluxgate type current detector is adopted.

FIG. 10 is a configuration diagram of an example in which the failure point distance detection device according to the fourth embodiment of the present invention is applied to a three-phase three-wire power circuit. An example of this fourth embodiment is a fault phase current detector (current detector with a small internal resistance) 18 and a healthy phase current detector (current detector with a small internal resistance) with respect to the first embodiment shown in FIG. Instead of 19, a differential current detector (differential flux gate type current detector) 24 is provided. In FIG. 10, as in the case of FIG. 1, the faulty phase is the T phase, the healthy phase is the R phase and the S phase, and the faulty phase T phase and the healthy phase S phase are short-circuited by the short-circuit device 17. Shows the case. The same elements as those in FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 10, the differential current detector 24 is a differential magnetic field detection type current detector (differential flux gate type current detector), and can detect a minute direct current. That is, the difference current detector 24 is a current detector having substantially zero internal resistance, and the faulty phase current I1 and the healthy phase current I2 are input in opposite directions to obtain the faulty phase current I1 and the healthy phase current I2. The difference current I12 of is detected. The difference current I12 is represented by the following equation (32).

I12 = I1-I2 ... (32)
Since the difference current detector 24 has virtually zero internal resistance, even a minute current can be detected with high accuracy. The faulty phase current I1 is a current flowing from the DC power supply device 15 through the fault point G, branching at the fault point G, passing through the faulty phase, and returning to the DC power supply device 15, and the healthy phase current I2 is a healthy phase current I2. This is the current flowing from the DC power supply device 15 to the second ground fault circuit that passes through the failure point G, branches at the failure point G, passes through the healthy phase, and returns to the DC power supply device 15. Therefore, when the failure resistance Rg at the failure point G is large, the failure phase current I1 and the healthy phase current I2 are minute currents, but the difference current detector 24 has the difference current I12 between the failure phase current I1 and the healthy phase current I2. Can be detected accurately.

The total current detector 20 inputs the faulty phase current I1 and the healthy phase current I2 that have passed through the difference current detector 24, and detects the total current I3 of the sum of the faulty phase current I1 and the healthy phase current I2. Since the total current detector 20 is connected to the DC power supply device 15 in series and is not connected to the first diversion circuit or the second diversion circuit, the diversion ratio does not become a problem.

The distance calculation device 21 inputs the difference current I12 detected by the difference current detector 24 and the total current I3 detected by the total current detector 20, and based on these currents, the transmission end 11 of the three-phase power line. The distance from the failure point G to the failure point x1 and the distance from the end 12 of the three-phase power line to the failure point x2 are calculated.

Substituting I1 represented by the formula (10) into I1 of the formula (32) and substituting I1 represented by the formula (11) into I2, the difference current I12 is represented by the following formula (33).

I12 = {(Rt2 + Rs-Rt1) / (Rt1 + Rt2 + Rs)} · I3 ... (33)
Here, Rs is r · L from the formula (4), Rt1 is r · x1 from the formula (5), Rt2 is r · x2 from the formula (6), and r · x1 + r · x2 is r · L from the formula (3). Therefore, by substituting these into the equation (33), the equation (34) is obtained.

I12 = {L + (x2-x1) / 2L} ・ I3 ... (34)
Since x2 = L-x1 from the equation (3), the equation (35) can be obtained by substituting this into the equation (34).

I12 = (1-x1 / L)} ・ I3 ... (35)
Now, let the difference current I12 / total current I3 be the third index value E3. Then, by substituting (I12 / I3) = E3 into the equation (35) and solving the distance x1 from the power transmission end to the failure point, the equation (36) is obtained. The calculated value x1 obtained by the equation (36) is defined as the distance x1 from the power transmission end to the failure point G.

x1 = L · (1-E3) ... (36)
Next, the distance x2 from the end 12 of the power circuit to the failure point G is the same until the equation (34) for obtaining the distance x1 from the power transmission end 11 of the power circuit to the failure point G is obtained. By substituting x1 = L-x2 obtained from the formula (3) into the formula (34), the formula (37) is obtained.

I12 = (x2 / L) ・ I3 ... (37)
Then, by substituting (I12 / I3) = E3 into the equation (37) and solving the distance x2 from the terminal 12 of the power circuit to the failure point, the equation (38) is obtained. The calculated value x2 obtained by the equation (38) is defined as the distance x2 from the end 12 of the power circuit to the failure point G.

x2 = L ・ E3 ... (38)
In the above description, when the faulty phase is the T phase and the healthy phase is the R phase and the S phase, the fault point is from the transmission end 11 of the three-phase power line using the T phase of the fault phase and the S phase of the healthy phase. The case of calculating the distance x1 to G and the distance x2 from the end 12 of the three-phase power line to the failure point G has been described, but as shown in FIG. 11, the R phase of the healthy phase is used instead of the S phase of the healthy phase. It may be used to calculate the distance x1 and the distance x2 using the T phase of the faulty phase and the R phase of the healthy phase.

Furthermore, the distances x1 and x2 calculated using the T phase of the faulty phase and the R phase of the healthy phase, and the distances x1 and x2 calculated using the T phase of the faulty phase and the S phase of the healthy phase are calculated, respectively. , You may try to take the average value of these. Since the distances x1 and x2 are calculated for not only one healthy phase but also two healthy phases, the DC resistance Rr of the R phase power line, the DC resistance Rs of the S phase power line, and the DC resistance Rt of the T phase power line. If there is a variation in the DC resistance value of, the variation can be corrected.

Further, in the above description, the case where it is applied to a three-phase three-wire power circuit has been described, but a three-phase four-wire power circuit, a single-phase two-wire power circuit, and a single-phase three-wire power circuit have been described. It can also be applied to a DC 2-wire power circuit. The application to a three-phase four-wire power circuit, a single-phase two-wire power circuit, a single-phase three-wire power circuit, and a DC two-wire power circuit is the same as in the case of the first embodiment. Is omitted.

FIG. 12 is a circuit diagram of a matching test circuit for performing test adjustment and accuracy matching between the total current detector 20 and the difference current detector 24. FIG. 12 shows a case where the failure point distance detection device according to the fourth embodiment of the present invention is applied to a single-phase two-wire power circuit, from the power transmission end 11 of the power circuit targeted for failure point distance detection. The illustration on the terminal side is omitted.

As shown in FIG. 12, in the matching test circuit, the faulty phase current I1 passing through the difference current detector 24 is connected to the negative terminal of the DC power supply device 15 via the confluence point B with respect to the single-phase two-wire power circuit. A switch S1 is provided in front of the confluence point B of the return path. Further, a switch on a path that branches from the path that leads the healthy phase current I2 to the difference current detector 24 in the direction opposite to the faulty phase current I1 and returns to the negative terminal of the DC power supply device 15 via the switch S1 and the confluence point B. A switch S2 is provided in front of S1. Further, a switch S3 is provided between the DC power supply device 15 and the faulty phase in front of the power transmission end 11, and a switch S4 is provided between the DC power supply device 15 and the healthy phase in front of the power transmission end 11.

Then, the test adjustment and the accuracy matching test between the total current detector 20 and the difference current detector 24 are performed in a state where the faulty phase and the sound phase of the power transmission end 11 of the power circuit to be detected at the fault point distance are open. .. In FIG. 12, a cross indicates that the faulty phase and the healthy phase of the power transmission end 11 are opened. Table 1 shows the open / closed pattern of the switches S1 to S4 at the time of the matching test and the actual measurement.

表１の１、２、３、４はスイッチＳ１～Ｓ４の開閉状態のパターンを示し、×はスイッチが開、○はスイッチが閉であることを示す。まず、パターン１、２、３は整合試験のパターン、パターン４は実測時のパターンである。測定誤差は、測定誤差＝測定値－真値で示される。いま、Ａ１２は差電流検出器２４の検出値で測定値であり、Ａ３は合計電流検出器２０の検出値（Ａ３＝Ｉ３）で真値であるとする。

Table 1, 1, 2, 3 and 4 show the open / closed pattern of the switches S1 to S4, where x indicates that the switch is open and ◯ indicates that the switch is closed. First, patterns 1, 2 and 3 are matching test patterns, and pattern 4 is a pattern at the time of actual measurement. The measurement error is indicated by measurement error = measured value-true value. Now, it is assumed that A12 is a measured value by the detection value of the difference current detector 24, and A3 is a true value by the detection value (A3 = I3) of the total current detector 20.

In pattern 1, switches S1, S2, and S3 are open and switch S4 is closed, and the difference current detector (A12) 24 has a healthy phase current I2 for testing directly from the DC power supply device 15 in the negative direction ( It shows a state in which the current flows in from the direction opposite to the fault phase current I1). That is, I2 (-) flows through the difference current detector (A12) 24, the current detected by the difference current detector (A12) 24 is I2, and the failure current I1 is the difference current detector (A12) 24. Since it does not flow, it indicates that the current detected by the total current detector (A3) 20 is also I2.

Since the measurement error e21 = the measured value A12-the true value A3, the current detected by the difference current detector (A12) 24 is I2 (-), and the current detected by the total current detector (A3) 20 is I3. The error e21 of the difference current detector (A12) 24 is {e21 = A12-A3 = I2 (-)-I3}. Therefore, when the current I2 (-) detected by the difference current detector (A12) 24 and the current I3 detected by the total current detector (A3) 20 are equal to I2, that is, (-A12 = A3 = I2). In some cases, the error e21 of the difference current detector (A12) 24 is zero.

In the pattern 2, the switches S1 and S3 are closed and the switches S2 and S4 are open, and the fault phase current I1 for the test is directly connected to the difference current detector (A12) 24 from the DC power supply device 15 in the positive direction ( It shows a state in which the current flows from the direction opposite to that of the sound phase current I2 in the opposite direction, that is, in the forward direction. That is, I1 (+) flows in the difference current detector (A12) 24, the current detected by the difference current detector (A12) 24 is I1, and the healthy phase current I2 is in the difference current detector (A12) 24. Does not flow, indicating that the current detected by the total current detector (A3) 20 is also I1.

Since the measurement error e21 = the measured value A12-the true value A3, the current detected by the difference current detector (A12) 24 is I1 (+), and the current detected by the total current detector (A3) 20 is I3. The error e12 of the difference current detector (A12) 24 is {e12 = A12-A3 = I1 (+)-I3}. Therefore, when the current value I (+) detected by the difference current detector (A12) 24 and the current I3 detected by the total current detector (A3) 20 are equal to I1, that is, (A12 = A3 = I1). If, the error e12 of the difference current detector (A12) 24 is 0.

In the pattern 3, the switches S1 and S4 are open and the switches S2 and S3 are closed, and the fault phase current I1 for the test is directly applied to the difference current detector (A12) 24 from the DC power supply device 15 from the positive direction. It shows a state in which the current flows in and passes through the switch S2 to become a healthy phase current I2 (−) in the opposite direction and flows into the difference current detector (A12) 24. That is, I1 (+) and I2 (−) flow through the difference current detector (A12) 24, and the current detected by the difference current detector (A12) 24 is I1 (+) + I2 (−) = 0. It shows that the current detected by the total current detector (A3) 20 is I1 (= 12).

The error e1221 of the difference current detector (A12) 24 is the measurement error e1221 = measured value A12-true value A3, and the current detected by the difference current detector (A12) 24 is I1 (+) + I2 (-), total. Since the current detected by the current detector (A3) 20 is I3, it is [e1221 = A3-A12 = I3- {I2 (−) + I (+)}]. Therefore, when the current value {I2 (−) + I (+)} detected by the difference current detector (A12) 24 is 0, that is, when (A12 = 0), the difference current detector (A12) The error e1221 of) 24 is 0.

In pattern 4, the faulty phase and the healthy phase of the transmission end 11 shown in FIG. 12 are connected to the power circuit, the switch S1 is closed, the switches S2, S3, and S4 are open, and the difference current detector (difference current detector). The actual failure phase current I1 passing through the failure point G flows from the DC power supply device 15 into A12) 24 from the positive direction, and the actual healthy phase current I2 passing through the failure point G from the DC power supply device 15 is negative. It shows the state of flowing in from the direction. That is, the actual I1 (+) and I2 (−) flow through the difference current detector (A12) 24, and the current detected by the difference current detector (A12) 24 is I1 (+) + I2 (−). It shows that the current detected by the total current detector (A3) 20 is I1 (+) +12 (−).

The matching of the detection accuracy of the difference current detector (A12) 24 is an error from I12 to I12 of E3 (= I12 / I3) in Eq. (36) for the error e1221 of the difference current detector (A12) 24. It is performed by calculating and obtaining the distance x1 from the transmission end 11 to the failure point G by the equation (39) obtained by substituting (I12-e1221) obtained by subtracting e1221.

x1 = L · {1- (I12-e1221) / I3} ... (39)
Similarly, the distance x2 from the terminal 12 to the failure point G is obtained by substituting (I12-e1221), which is obtained by subtracting the error e1221 from I12, into I12 of E3 (= I12 / I3) in the equation (38). By calculating and obtaining by the formula 40), the detection accuracy of the difference current detector (A12) 24 is matched.

x2 = L · (I12-e1221) / I3 ... (40)
As a result, the total current detector (A3) 20 can accurately detect the total current I3 of the actual fault phase current I1 via the fault point G and the actual healthy phase current I2 via the fault point G.

In the above explanation, the matching test circuit applied to the single-phase two-wire type power circuit is shown, but the three-phase three-wire type power circuit, the three-phase four-wire type power circuit, and the single-phase three-wire type power circuit are shown. Similarly, the matching test circuit can be applied to the DC 2-wire circuit.

According to the fourth embodiment of the present invention, since the principle of current detection of the differential current detector 24 is a non-contact type by magnetic field detection, there is no internal resistance. Further, in the fourth embodiment of the present invention, instead of the faulty phase current detector 18 and the healthy phase current detector 19 of the first embodiment, the faulty phase current detector 18 and the healthy phase current detector 19 are simply one unit. Instead of replacing two magnetic field detection type current detectors (flux gate type current detector), one differential magnetic field detection type current detector (differential flux gate type current detector) Since the difference current I12 between the faulty phase current I1 and the healthy phase current I2 is detected, there is no individual error in each of the current detectors.

That is, the distance x1 from the transmission end 11 of the failure phase to the failure point G and the termination 12 are used by using the difference current I12 between the failure phase current I1 and the healthy phase current I2 detected by one difference current detector 24. Since the distance x2 from the failure point G to the failure point G is calculated, the distances x1 and x2 to the failure point G can be calculated accurately. Since the total current detector 20 is not connected to the divergence circuit, it does not affect the divergence ratio and does not cause a problem. Therefore, it is not necessary to adopt a current detector having a small internal resistance.
<Fifth Embodiment>
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, the calculated value of the distance x1 from the power transmission end 11 to the failure point G calculated in the first to third embodiments and the calculated value of the distance x2 from the terminal 12 to the failure point G are corrected. It is something like that.

In the first embodiment and the second embodiment, the distance x1 from the transmission end 11 to the failure point G is obtained as the average value of the calculated value x11 and the calculated value x12, and the distance x2 from the terminal 12 to the failure point G is the calculated value. It is obtained as the average value of x21 and the calculated value x22, and in the third embodiment, the distance x1 from the transmission end 11 to the failure point G is obtained as the calculated value x12, and the distance x2 from the terminal 12 to the failure point G is used as the calculated value x22. The sum of the calculated value of the distance x1 from the transmission end 11 to the failure point G and the calculated value of the distance x2 from the end point 12 to the failure point G is the distance L of the power line from the transmission end 11 to the end point 12. On the other hand, in the case of excess or deficiency, the sum of the distance x1 from the transmission end 11 to the failure point G and the distance x2 from the end point 12 to the failure point G is the distance L of the power line from the transmission end 11 to the end point 12. Corrected to.

That is, when the sum (x1 + x2) of the distance x1 from the power transmission end 11 to the failure point G and the distance x2 from the end point 12 to the failure point G is greater than the distance L of the power line from the power transmission end 11 to the end point 12 by α1. Only α1 / 2 is subtracted from the calculated value x1 and the calculated value x2 to obtain the distance x1 from the power transmission end 11 to the failure point G and the distance x2 from the terminal 12 to the failure point. As a result, the sum of the distance x1 and the distance x2 becomes equal to the distance L of the power line, and the accuracy of the distance to the failure point is improved.

On the other hand, when the sum (x1 + x2) of the distance x1 from the power transmission end 11 to the failure point G and the distance x2 from the end point 12 to the failure point G is smaller by α2 than the distance L of the power line from the power transmission end 11 to the end point 12. Only α2 / 2 is added to the calculated value x1 and the calculated value x2 to obtain the distance x1 from the power transmission end 11 to the failure point G and the distance x2 from the terminal 12 to the failure point G. As a result, the sum of the distance x1 and the distance x2 becomes equal to the distance L of the power line, and the accuracy of the distance to the failure point is improved.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

11 ... Transmission end, 12 ... Termination, 13 ... Insulation resistance tester, 14 ... Ammeter, 15 ... DC power supply device, 16 ... Variable resistance, 17 ... Short circuit device, 18 ... Failure phase current detector, 19 ... Sound phase current detection Instrument, 20 ... Total current detector, 21 ... Distance calculation device, 22 ... Switching device, 23 ... Combined current detector, 24 ... Difference current detector

Claims (6)

When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the DC power supply device passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the failure phase, and passes through the confluence point on the transmission end side. A fault phase current detector that detects the fault phase current I1 flowing through the first ground fault circuit that returns to the negative terminal of
From the positive terminal of the DC power supply device, the DC power supply passes through the failure point, branches at the failure point, passes through the termination of the failure phase and the short-circuit device, passes through the healthy phase, and passes through the confluence point on the transmission end side. A healthy phase current detector that detects the healthy phase current I2 flowing through the second ground fault circuit that returns to the negative terminal of the device, and
A total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The faulty phase current detector and the healthy phase current detector are ammeters whose internal resistance is smaller than the resistance value of the power line.
The faulty phase current I1 / the total current I3 is defined as the first index value E1, the healthy phase current I2 / the total current I3 is defined as the second index value E2, and the distance of the power line from the transmission end to the end is L. When
The distance x1 from the power transmission end to the failure point is calculated separately by the following equations (a) and (b), respectively.
x11 = 2L · (1-E1) ... (a), x12 = 2L · E2 ... (b)
The distance x1 from the power transmission end to the failure point is obtained as the average value of the calculated value x11 and the calculated value x12.
The distance x2 from the end point to the failure point is calculated separately by the following equations (c) and (d), respectively.
x21 = L · (2E1-1) ... (c), x22 = L · (1-2E2) ... (d)
A failure point distance detecting device, characterized in that the distance x2 from the end to the failure point is obtained as an average value of a calculated value x21 and a calculated value x22. When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the DC power supply device passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the failure phase, and passes through the confluence point on the power transmission end side. The first ground fault circuit returning to the negative terminal and the positive terminal of the DC power supply device pass through the failure point, branch at the failure point, pass through the termination of the failure phase and the short circuit device, and pass through the healthy phase. A switching device that switches the second ground fault circuit that passes through the confluence on the power transmission end side and returns to the negative terminal of the DC power supply device at the power transmission end of the power line.
When connected to the first ground fault circuit by switching between the first ground fault circuit and the second ground fault circuit in the switching device, the fault phase current I1 flowing in the first ground fault circuit is detected and said. A combined current detector that detects the healthy phase current I2 flowing in the second ground fault circuit when connected to the second ground fault circuit, and
The combined current detector is an ammeter whose internal resistance is smaller than the resistance value of the power line.
A total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The faulty phase current I1 / the total current I3 is defined as the first index value E1, the healthy phase current I2 / the total current I3 is defined as the second index value E2, and the distance of the power line from the transmission end to the end is L. When
The distance x1 from the power transmission end to the failure point is calculated separately by the following equations (a) and (b), respectively.
x11 = 2L · (1-E1) ... (a), x12 = 2L · E2 ... (b)
The distance x1 from the power transmission end to the failure point is obtained as the average value of the calculated value x11 and the calculated value x12.
The distance x2 from the end point to the failure point is calculated separately by the following equations (c) and (d), respectively.
x21 = L · (2E1-1) ... (c), x22 = L · (1-2E2) ... (d)
A failure point distance detecting device, characterized in that the distance x2 from the end to the failure point is obtained as an average value of a calculated value x21 and a calculated value x22. The failure point according to claim 1 or 2, wherein the distance x1 from the transmission end to the failure point is a calculated value x12, and the distance x2 from the end to the failure point is a calculated value x22. Distance detector. When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the power transmission passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the termination of the failure phase and the short-circuit device, and passes through the healthy phase. A healthy phase current detector that detects the healthy phase current I2 flowing through the second ground fault circuit that passes through the confluence on the end side and returns to the negative terminal of the DC power supply unit.
A first ground fault circuit that passes from the positive terminal of the DC power supply device, passes through the failure point, branches at the failure point, passes through the failure phase, passes through the confluence point on the transmission end side, and returns to the minus terminal of the DC power supply device. The total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The healthy phase current detector is an ammeter whose internal resistance is smaller than the resistance value of the power line.
When the healthy phase current I2 / the total current I3 is the second index value E2 and the distance of the power line from the transmission end to the end is L.
The distance x1 from the power transmission end to the failure point is calculated by the following equation (b).
x12 = 2L ・ E2 ... (b)
The distance x1 from the power transmission end to the failure point is obtained as a calculated value x12.
The distance x2 from the end point to the failure point is calculated by the following equation (d).
x22 = L · (1-2E2) ... (d)
A failure point distance detecting device, characterized in that the distance x2 from the end point to the failure point is obtained as a calculated value x22. When it is detected that a failure has occurred between the power line of the power circuit and the ground, the power line in which the failure has occurred is set as the failure phase, the power line in which the failure has not occurred is set as the healthy phase, and the power circuit is three-phase 3 In the case of the linear system, the end of one of the failed phase and the healthy phase of the three-phase power lines is short-circuited with the three-phase three-wire system power circuit stopped, and the power is short-circuited. When the circuit is a three-phase four-wire system, the faulty phase of the three-phase power lines and one of the healthy phase and the neutral wire are used with the three-phase four-wire system power circuit stopped. When the end of one phase of the above is short-circuited and the power circuit is a single-phase two-wire system or a DC two-wire system, the power circuit of the single-phase two-wire system or the DC two-wire system is stopped. When the faulty phase and the end of the healthy phase are short-circuited and the power circuit is a single-phase three-wire system, the faulty phase, the healthy phase, and the sound phase are described while the power circuit of the single-phase three-wire system is stopped. A short-circuit device that short-circuits the end of one of the neutral wires, and
A DC power supply device in which the positive terminal is grounded to the ground and the negative terminal is connected to the power transmission end of the power line short-circuited by the short-circuit device at the end of the power line to apply a negative DC voltage from the power transmission end of the power line.
From the positive terminal of the DC power supply device, the DC power supply device passes through the failure point, which is the failure position of the power line in which the failure occurred , branches at the failure point, passes through the failure phase, and passes through the confluence point on the transmission end side. The faulty phase current I1 flowing through the first ground fault circuit returning to the negative terminal of the current and the positive terminal of the DC power supply device pass through the fault point, branch at the fault point, and pass through the termination of the fault phase and the short circuit device to be sound. A differential current detector that detects the differential current I12 from the healthy phase current I2 that flows through the second ground fault circuit that passes through the confluence point on the transmission end side via the phase and returns to the negative terminal of the DC power supply device.
A total current detector for detecting the total current I3, which is the sum of the faulty phase current I1 and the healthy phase current I2, is provided.
The differential current detector is a differential magnetic field detection type that detects the difference current I12 between the faulty phase current I1 and the healthy phase current I2 by inputting the faulty phase current I1 and the healthy phase current I2 in opposite directions. Current detector,
When the difference current I12 / the total current I3 is the third index value E3 and the distance of the power line from the transmission end to the end is L.
The distance x1 from the power transmission end to the failure point is calculated by the following equation (e).
x1 = L · (1-E3) ... (e)
The distance x2 from the end point to the failure point is calculated by the following equation (f).
x2 = L ・ E3 ... (f)
A failure point distance detecting device for obtaining a distance x1 from the power transmission end to the failure point and a distance x2 from the end to the failure point. In the failure point distance detecting device according to any one of claims 1 to 4, the sum of the distance x1 from the transmission end to the failure point and the distance x2 from the end to the failure point (x1 + x2). Is greater than the distance L of the power line from the transmission end 11 to the terminal 12 by α1. The distance x2 to the failure point is obtained, while the sum (x1 + x2) of the distance x1 from the transmission end 11 to the failure point G and the distance x2 from the end point 12 to the failure point G is the power line from the transmission end 11 to the end point 12. When it is smaller than the distance L by α2, add only α2 / 2 to the calculated value x1 and the calculated value x2 to obtain the distance x1 from the transmission end 11 to the failure point G and the distance x2 from the terminal 12 to the failure point G. A featured failure point distance detector.

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