JPH0418272B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an overhead ground wire ground fault section determining method and apparatus for determining a ground fault section of an overhead ground wire.

[Summary of the invention] A method for determining a ground fault section of an overhead ground wire according to the present invention includes:
When a ground fault occurs between two points, we focus on the points where the currents are in opposite phases at those two points, extract half-wave signals of the current flowing at each of those two points, and synthesize these half-wave signals. Then, by counting the number, the number of counts in the accident section is approximately twice that of the healthy section, and this is used to determine the ground fault section.

The ground fault section determination device for an overhead ground wire according to the present invention includes:
Current detectors are installed at two points on the overhead ground wire, and each half-wave signal of the current flowing there is extracted and outputted as an optical signal, and each of the optical signals is transmitted through an optical fiber. This system determines the ground fault section by combining the signals given from the optical fibers with a ground fault section detector and counting the number of signals, and also prevents erroneous signals from entering during the half-wave signal transmission process. be.

[Prior Art] Conventional power transmission line failure point locating methods include a surge reception method and a pulse radar method.

[Problems to be Solved by the Invention] However, the surge reception method has the problem of malfunction, while the pulse radar method cannot be used on power transmission lines with branches and has problems such as poor separation performance.

An object of the present invention is to provide a method and apparatus for determining a ground fault section of an overhead ground wire, which can accurately determine a ground fault section.

[Means for solving the problems] The means of the present invention for achieving the above object are as follows:
An explanation will be given with reference to FIGS. 1 to 4, which correspond to embodiments.

The method for determining the ground fault section of an overhead ground wire according to the present invention is as follows:
A device that extracts half-wave signals of the current flowing at two points a certain distance apart on the overhead ground wire 2, synthesizes these half-wave signals, and determines the ground fault section by counting the number of half-wave signals. It is.

The device for determining the ground fault section of an overhead ground wire according to the present invention is installed at two points separated by a certain distance on the overhead ground wire 2, and extracts the half-wave signals of the current flowing there and converts them into optical signals. A current detector that outputs a current detector, an optical fiber that transmits each of the optical signals, and a ground fault section detector that combines signals input through each of the optical fibers and counts the number of signals to determine a ground fault section. It is characterized by consisting of.

[Effect] According to the method for determining the ground fault section of an overhead ground wire as described above, the count number in the accident section is approximately twice that of the healthy section, so the count number is significantly different between the accident section and the healthy section. By checking, the ground fault section can be accurately determined.

According to the device for determining the ground fault section of an overhead ground wire as described above, each half-wave signal of the current flowing through the overhead ground wire is extracted, and this is converted into an optical signal to detect the ground fault section using an optical fiber. Since the detection signal is sent to the detector, it is possible to avoid the introduction of erroneous signals in the process of transmitting the detection signal and to accurately determine the ground fault section.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 4. In this embodiment, 1 span between the pylons 1 of the overhead ground wire 2 installed on the pylon 1 is 1 span.
A current detector 3 is attached to each end of the section. This current detector 3 includes a current transformer 4
and a light emitting diode 6 and a protection diode 7 connected in antiparallel to this via a current limiting resistor 5.
It consists of. The current transformers 4 at both ends of one section have the same polarity so that currents of the same phase can be taken out during normal operation. The optical signal output from the current detector 3 is transmitted via an optical fiber 8 to a ground fault section detector 9. This ground fault section detector 9 includes an optical multiplexer that combines optical signals sent via an optical fiber 8 from current detectors 3 at both ends of the section to be detected, and an optical multiplexer that combines the number of optical signals that have been combined. It consists of a counter for counting. The output signal from the counter is again converted into an optical signal and transmitted to the terminal station via the optical fiber 10, so that the point of failure can be comprehensively determined.

Therefore, when a ground fault occurs, part of the ground fault current flows to the overhead ground wire 2. When a ground fault occurs between points A and B, the current flowing through point A and the current flowing through point B have opposite phases as shown in A and B in FIG. 3. When these currents are detected by the current detectors 3 at points A and B, and flow through the light emitting diode 6, they are each half-wave rectified as shown in A and B in FIG. Light is emitted with the waveforms shown in A and B, respectively,
Each of the optical signals is transmitted through an optical fiber 8 and input to a ground fault section detector 9, respectively. In the ground fault section detector 9, each optical signal is combined by the optical combiner and then the third
The signal will be as shown in FIG. In other words, since the signals at point A and point B are in opposite phase, when they are combined, the other signal enters the interval where one signal is zero, and the number of signals is measured at point A or point B in a certain period of time. This is approximately twice the number. This number of signals is counted by a counter in the ground fault section detector 9 for a certain period of time, and the count result is transmitted as an optical signal to the terminal station via the optical fiber 10, and the detection results of other sections are similarly transmitted to the terminal station. do.

When no ground fault occurs between points A and B, the current waveforms at points A and B are in phase as shown at A and B in FIG. 41. Therefore, the half-wave rectified waveforms become as shown in A and B in FIG. 4, and when these are combined, the signals overlap each other as shown in FIG. 4, and the number of signals does not increase. This is approximately 1/2 of the number of signals when a ground fault occurs.

At the terminal station, by comparing the count numbers of each section, since the count numbers are significantly different between the ground fault section and the healthy section, it is possible to reliably determine the ground fault section.

If the frequency of the ground fault current is known, it is possible to determine whether or not the area is in a ground fault accident area by measuring only one area.

The measurement span is not limited to between steel towers, and may be several spans, but the determination range will be wider.

Although it is efficient to use optical fibers in the optical composite overhead ground line as transmission paths for optical signals, depending on the case, separate optical fibers may be installed in parallel.

It is preferable to count the number of waveforms by shaping the waveforms into pulses. It is appropriate to count using a microprocessor.

Although an induced current flows through the overhead ground wire 2 at all times, by selecting the threshold level of the light emitting diode 6 to be larger than the normal current value, it can be set so that it can emit light only in the event of an accident.

[Effects of the Invention] As explained above, the method for determining a ground fault section of an overhead ground wire according to the present invention focuses on the fact that the currents are in opposite phases on both sides of the ground fault section, and divides the current by half. By rectifying the waves, combining them, and counting the number of waves, the accident section is approximately twice as large as the healthy section.
Since the number of counts is doubled, the difference is large, so
It is possible to accurately determine whether or not the area is in a ground fault area.

In addition to the above-mentioned effects, the ground fault section determination device for an overhead ground wire according to the present invention converts the signal transmission into an optical signal and uses an optical fiber.
This has the advantage that judgment can be made while avoiding the mixing of erroneous signals.

[Brief explanation of drawings]

FIG. 1 is a side view showing a schematic configuration of an embodiment of a device according to the present invention, FIG. 2 is a circuit diagram showing an example of a current detector used in the present invention, and FIG. 3 is a side view showing a schematic configuration of an embodiment of a device according to the present invention. FIG. 4 is a waveform diagram of an accident section and a waveform diagram of a healthy section in the case of the method of the present invention. 1... Steel tower, 2... Overhead ground wire, 3... Current detector, 4... Current transformer, 6... Light emitting diode, 7... Diode, 8... Optical fiber, 9...
...Ground fault section detector.

Claims (1)

[Claims] 1. Ground faults can be detected by extracting half-wave signals of the current flowing at two points separated by a certain distance from an overhead ground wire, combining these half-wave signals, and counting the number of half-wave signals. A method for determining a ground fault section of an overhead ground wire, the method comprising determining the section. 2. A current detector installed at two points separated by a certain distance on an overhead ground wire, each extracting a half-wave signal of the current flowing therethrough and outputting it as an optical signal, and a light source transmitting each of the above-mentioned optical signals. A ground fault section determining device for an overhead ground wire, which comprises a fiber and a ground fault section detector that combines signals input through each of the optical fibers and counts the number to determine a ground fault section.