JPH02266272A - Measurement of faulty point on aerial transmission line - Google Patents

Abstract

PURPOSE:To detect an accident occurred in any point throughout the overall length of an aerial transmission line by measuring a temperature distribution in the lengthwise direction of an overhead ground line from a backward scattered beam distribution of an optical fiber on the conjugated overhead ground line of optical fiber. CONSTITUTION:A measuring device 15 for temperature distribution is connected to one end of the conjugated overhead ground line 3 of optical fiber through the optical fiber 8, and a Raman scattering beam pulse generated in the optical fiber of the overhead ground line 3 by a laser pulse beam which is entered from the device 15 is detected by a time division. Since this pulse size depends on the temperature, the temperature distribution corresponding to a current distribution throughout the overall length of overhead ground line 3 can be obtained in the device 15. Temperature distribution signals measured in the device 15 are accumulated in a signal processing device 17. When a trip signal corresponding to the fault is generated, the value of the difference between the temperature distribution signal measured one time before the time receiving a trigger signal which is generated in a trigger signal generator 16 and the temperature distribution signal at the time immediately after receiving the trigger signal is calculated by the device 17 to obtain a distribution of the temperature rise values, thereby a point showing highest temperature rise is decided as the faulty point.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting a fault point in an overhead power transmission line.

[Prior Art] Conventionally, as shown in Fig. 3, a method for detecting a fault point in an overhead power transmission line using an optical fiber composite overhead ground wire is as follows.
A detector 1 and a light source 2 for accident information signals with a wavelength unique to each tower are installed in each tower, and the optical signal is transmitted from other towers by an optical multiplexer/demultiplexer 4 installed in an optical fiber overhead ground wire 3. A method is known in which the optical signal is sent to a central identification device using a gold wave.

However, there is a limit to the number of optical fibers that can be housed in an optical fiber composite overhead ground wire, and there are many towers from which information must be collected, and losses due to optical demultiplexers are large. Attempts have been made to improve this problem, and a detection method as shown in FIGS. 4 and 5 has been considered (Japanese Patent Application Laid-open No. 141121/1983).

That is, as shown in FIG. 4, a discrimination bag 7!1 is provided for each steel tower 5.
6, as shown in FIG.
0, the fault current detection section 13, and the winding and bending section 10.
The drive unit 7 is connected to the drive unit 7 via an arm 11 and applies a force in a direction to change the degree of winding and bending. The drive unit 7 is driven by the output of the fault current detection unit 13 to bend the optical fiber 8 and change the optical transmission loss. 0TDR (Optical Tin
eDonaine Reflectonetry) 12, and transmit light from the location where optical transmission loss occurs (A in Figure 6).
points) are detected as accident points.

[Problem to be solved by the invention] However, the prior art described above has the following problems.

(1) Because accidents are determined for each tower, it is not possible to detect the location of the accident point on the overhead power transmission line between the towers.

(2) Since it is necessary to install a detector on each tower, the longer the IBM, the more expensive it becomes.

(3) When detecting a fault point based on loss changes such as bending an optical fiber, there is a risk that repeated bending of the optical fiber may cause the strength of the optical fiber to deteriorate and lead to TLI lines.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide an inexpensive and simple fault point detection method that can detect faults occurring at any point along the entire length of an overhead power transmission line.

[Means for Solving the Problems] The method for detecting a fault point in an overhead power transmission line of the present invention is based on the backscattered light distribution of an optical fiber in an optical fiber composite overhead ground wire in which an optical fiber is built into the overhead ground wire. The temperature distribution in the longitudinal direction of the overhead ground wire is measured, and the point of failure is detected from the point of change in the temperature distribution.

Preferably, after receiving an overhead transmission line system trip signal, the temperature distribution in the longitudinal direction of the optical fiber is immediately measured using this as a trigger signal, the difference value of the temperature distribution before and after receiving the trip signal is determined, and this difference value is calculated. Detect failure points from change points.

[Operation] The distribution of temperature rise values is approximately proportional to the distribution of fault current flowing through the optical fiber composite overhead ground wire.

Since the fault point is determined from continuous changes in temperature distribution of the optical fiber composite overhead ground wire, all faults that occur at any point can be detected, regardless of whether it is at the tower or in the center between the towers. Therefore, detection accuracy is greatly improved.

In the configuration in which 31 measurements of the temperature distribution are started after receiving a trigger signal, the failure point is located after detecting the occurrence of a failure, resulting in high measurement accuracy.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the accident point detection method of the present invention.

In the figure, 3 is an optical fiber composite overhead ground wire, 8 is an optical fiber drawn out from this optical fiber composite overhead ground wire 3,
15 is a temperature distribution measuring device for determining temperature distribution from the distribution waveform of Raman scattered light by this optical fiber, 14 is a three-current transformer installed in the optical fiber composite overhead ground wire, 16 is a trigger signal generator, and 17 is a signal processing device. It is.

When a failure such as a ground fault occurs in a power transmission line, a larger current than normal flows through the optical fiber composite overhead ground wire 3, and the temperature of the optical fiber composite overhead ground wire 3 rises according to the current distribution in the longitudinal direction of the power transmission line. .

Therefore, a temperature distribution measuring device 15 is connected to one end of the optical fiber composite overhead ground wire 3 via an optical fiber 8, and a laser pulse beam is input from this temperature distribution measuring device 15 via the optical fiber 8, and the optical fiber composite By time-divisionally detecting the Raman scattered light pulses generated in the optical fiber in the overhead ground wire 3, the longitudinal distribution of the Raman scattered light can be obtained. Since the magnitude of this Raman scattered light pulse depends on the temperature, the temperature distribution measuring device 15 that detects it can determine the temperature distribution corresponding to the current distribution over the entire length of the optical fiber composite ground wire 3.

Here, the temperature distribution information for determining failure is measured by inputting the current value detected by the current transformer 14 attached to the optical fiber composite overhead ground wire 3 to the trigger signal generator 16 and monitoring it, and responding to the failure. When a trip signal from an overhead power transmission line is received, the trigger signal generator 16 converts it into a trigger signal that causes the temperature distribution measuring device 15 to start measurement, and transmits the trigger signal to the temperature distribution measuring device 15. be exposed.

The temperature distribution signal measured by the temperature distribution measurement device 15 is always stored in the memory of the signal processing device 17, and when a trip signal corresponding to a failure occurs, the signal processing device 17 outputs a trigger signal generator. The difference value between the temperature distribution signal measured one time before the trigger signal generated on 16th and the temperature distribution signal immediately after the trigger signal is received is calculated, and the distribution of temperature rise values is calculated. A large point is determined to be a failure point.

Therefore, the fault point is located after receiving the trigger signal and detecting the occurrence of a fault, resulting in high measurement accuracy.

Figure 2 shows an example of measuring the distribution of temperature rise values at the time of failure. The distribution of temperature rise values is approximately proportional to the distribution of fault current flowing through the overhead ground wire. In Figure 2, the distance M where the temperature rise value is high
Point r is detected as a failure point.

The method of detecting a fault in a power transmission line and generating a trigger signal is as follows:
In the above embodiment, the current value at the time of a fault is detected as a trip signal using a current transformer attached to the overhead ground wire.
, CT may be used, and there are no particular restrictions.

[Effects of the Invention] As described above, according to the present invention, the following excellent effects can be obtained.

(1) The power transmission lines and towers do not require anything other than optical fiber composite overhead ground wires, making it highly economical.

(2) Since the failure point is determined from continuous temperature distribution information of the optical fiber composite overhead ground wire, all failures that occur at any point can be detected, regardless of whether it is in the tower or in the center between the towers.

(3) Since the failure point can be located simply by placing a device at the end of the optical fiber overhead ground wire, there is no need for new construction.
It can be easily applied to existing railway lines.

(4) Overhead power transmission lines in operation can be constantly monitored.

(5) High reliability and accuracy as fault points can be determined from the temperature distribution over the entire length of the overhead ground wire.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device using the fault point detection method according to the present invention, FIG. 2 is a graph of the experimental results, FIGS. 3 and 4 are schematic diagrams showing the conventional fault point detection method, and FIG. The figure is a block diagram of a conventional discrimination device, and FIG. 6 is a graph diagram of experimental results of a conventional failure point detection method. In the figure, 3 is an optical fiber composite overhead ground wire, and 8 is an optical fiber
14 is a current transformer, 15 is a temperature distribution measuring device, 16 is a trigger signal generator, and 17 is a signal processing device. Figure 1 74: Tributary Spring Patent Applicant Tokyo Electric Power Co., Hitachi Cable Co., Ltd. Representative Patent Attorney Nobuo Kinutani Figure 2

Claims (1)

[Claims] 1. In an optical fiber composite overhead ground wire in which an optical fiber is built into the overhead ground wire, the temperature distribution in the longitudinal direction of the overhead ground wire is measured from the backscattered light distribution of the optical fiber, and the temperature is determined. A method for detecting fault points in overhead power transmission lines, characterized by detecting fault points from distribution change points. 2. After receiving a trip signal from the overhead power transmission line system, use this as a trigger signal to immediately measure the temperature distribution in the longitudinal direction of the optical fiber, find the difference value of the temperature distribution before and after receiving the trip signal, and calculate this difference value. 2. The method for detecting a fault point in an overhead power transmission line according to claim 1, wherein the fault point is detected from a change point.