JPH02124480A - Apparatus for spotting faulty section of underground transmission line - Google Patents

Abstract

PURPOSE:To secure synchronism between both intermediate stations and to improve judging accuracy by dividing a transmission line into a plurality of regions, and supplying a grounding current signal from a current detector which is provided at the boundary of each region to both intermediate stations in both neighboring regions. CONSTITUTION:Current transformers 200 and 300 are provided for a power cable line 100. The attaching position is, e.g. a cross bonding line 310 at the IJB of a single core cable. When the current transformer 300 located at the boundary between sections A and B detects a grounding current, a voltage signal is generated across both ends of a detecting resistor RD. Then LEDs PD1 and PD2 are driven, and the light beams at the same level and in the same phase are emitted. The light signals are received with intermediate stations A and B 500 through optical fiber cables 330, and optoelectronic transducing operation is performed. When the signal transmitted from the current transformer 200 is stored in a memory recorder with said signal as a trigger, the stored data have synchronism between the station A 500 and the station B 500. When the data having the synchronism are processed, highly reliable spotting can be performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fault section locating system for underground power transmission lines.
Especially the ground fault? is the absolute value of the flow (hereinafter referred to as "level")
This paper relates to a fault section locating system for underground power transmission lines that locates ground fault points based on phase and phase.

[Background technology]

As a system for locating ground fault sections of underground power transmission lines, the sheath circuit current at the time of a ground fault is detected by current detection devices installed at appropriate intervals in the longitudinal direction of the line, and the absolute value and phase distribution of the current are used to locate the ground fault section. A system has been proposed to identify the contact area. In other words, when the conductor and sheath are short-circuited due to dielectric breakdown of the cable, the fault area is located by utilizing the fact that the level and phase of the current flowing through the sheath changes significantly from the ground fault point. The principle will be explained with reference to FIGS. 4(a) and (b). In these figures,
The conductor 42 is insulated by the insulator 42a and the sheath 43
By being inserted into the underground power transmission line 41, an underground power transmission line 41 is formed. In FIG. 4(a), both ends of the conductor 42 are connected to a power source 44, and in FIG.
The right end side is connected to the power supply 44, and the left end side is connected to the load 45.

Under normal conditions, current flows through the conductor 4 due to power transmission from the power source 44.
2 in the direction of arrow 47. When such a ground fault occurs in the cable 41, the conductor current 47 is reversed on both sides of the ground fault point 46, and a sheath current flows through the sheath 43 (FIG. 4(a)). That is, a phase shift of about 180 @ occurs in the phase of the sheath current flowing in the sheath 43 on the left and right sides of the ground fault point 4G. On the other hand, in FIG. 4B, most of the conductor current 47 in the conductor 42 flows as a sheath current of 48.48 A at the ground fault point 46. In this case, ground fault point 4
6, the sheath current 4 flowing through the sheath 43 on the load 45 side
8A decreases. For this reason, the load 45
The level of the side sheath current 48A decreases, and the current value changes suddenly.

Such a phase reversal of the sheath current and a sudden change in its current value may occur either or both may occur depending on the power supply conditions of the underground power transmission line. Therefore, by measuring the level and phase of the sheath current at a predetermined location and comparing the measured values with the level and phase of the sheath current at other locations, it is possible to locate the ground fault point. In this system, section determination is performed for each current measurement point, so current detection devices are provided at appropriate intervals over the entire length of the line.

This allows the current during a ground fault to be measured at multiple locations at the same timing, and then compared in sequence. The current measurement point is usually a part such as an IJB that has a cross bond wire,
Detected by an instrument current transformer. The detected current is converted into an optical signal and transmitted to a processing station via an optical fiber, where the waveform of the current at each location is regenerated and a fault section is determined. Transmission using optical signals can avoid the influence of external induced disturbances.

[Problems to be solved by the invention C] As mentioned above, the failure section is determined by sequentially comparing the levels and phases of the ground fault current in adjacent parts to find areas where there is a large change. Concurrency of data acquisition is required. This is especially true for
This becomes important in the case of phase comparison. Data from multiple parts is captured into a multi-channel memory recorder, etc.
In terms of film production, the timing is such that the signal from any one of the corresponding channels is used as a trigger and the signals are captured at the same time. Therefore, there would be no problem if information on the total length of the line could be collected and processed in one place, but in practice there are the following problems.

(1) Since the amount of information is enormous, a computer that can handle it is required, and processing time is also required.

(2) Since ground fault information can be transmitted using optical fiber cables, it is subject to transmission distance limitations. In other words, it cannot be applied to lines whose length exceeds the permissible transmission distance.

These problems divide the track lengthwise into multiple regions,
A processing station that processes data for each area (hereinafter referred to as an “intermediate station”)
This can be solved by providing a However, it becomes very difficult to provide the above-mentioned simultaneity to each memory recorder among a plurality of intermediate stations, and there is a possibility that the trigger timing may differ for each intermediate station. Since both the level and phase of the ground fault current are relative comparisons, there is no problem with judgment at each intermediate station, but inevitably there is a risk that the phase will change significantly at the boundary between intermediate stations, resulting in incorrect judgment. There is a problem that this can be a factor.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fault section locating system for underground power transmission lines that can ensure simultaneity between a plurality of intermediate stations, thereby improving reliability and accuracy of determination.

[Means to solve the problem]

In order to achieve the above object, the present invention divides an underground power transmission line into a plurality of fault section determination areas, and detects the ground fault current signal of a current detection device installed at the boundary of each area. We provide a fault section locating system for underground power transmission lines that supply both intermediate stations.

In the underground power transmission line faulty section locating system of the present invention, the underground power transmission line is divided into a plurality of faulty section determination regions in the length direction, and an intermediate station is provided corresponding to each region.

Current detection devices are provided in each region at appropriate intervals.

The ground fault current detected by the current detection device is rectified as necessary and converted into a corresponding halo signal. This optical signal is transmitted via an optical fiber cable to an intermediate station corresponding to that area. Here, the ground fault current signal of the current detection device installed at the boundary of each area is supplied to both intermediate stations corresponding to the double-headed areas adjacent to the boundary simultaneously and without changing the level and phase. Therefore, if the ground fault current signal at the boundary is used as a trigger, the transmitted data will be stored in the memory recorder in a state with simultaneity among the plurality of intermediate stations. In this case, based on the ground fault current signal detected at the boundary of each region, for example, two electrical/optical conversion elements having the same characteristics and arranged in series are driven. By this driving, each electric/optical conversion element emits optical signals having the same level and phase.

This optical signal is desirably transmitted to both intermediate stations via two optical fiber cables with equal transmission line lengths. This optical signal is used at both intermediate stations as a trigger signal to provide simultaneity. Naturally, it will also be processed as data. In addition, in the present invention,
A master station is not necessarily required, and one of the intermediate stations may function as the master station.

〔Example〕

Hereinafter, the underground power transmission line fault section locating system of the present invention will be explained in detail.

FIG. 1 shows a first embodiment of the present invention, in which current transformers 200 and 300 are provided at appropriate intervals in the longitudinal direction of a power cable line 100 for measuring the sheath times +Y & current. The current transformers 200 and 300 are installed at, for example, a cross-bond wire in an IJB of a single-core cable, and in that case, it is desirable that three-phase components are combined together.

The outputs of the current transformers 200 and 300 are respectively electrical/optical converters 40
0 to each intermediate station 500. The intermediate station 500 collects current information of the current transformers 200 and 300, and determines a faulty section based on it. The electric cable line 100 is section A,
It is divided into intermediate stations A and B, and corresponding intermediate stations A and B.
, C500 are provided. Here, sections A, B, C
The current transformer 300 at the boundary detects the ground fault current for the adjacent intermediate station 500.

For example, the current transformer 300 at the boundary of section ASB is
500 and the change in the boundary of section B1C for intermediate station B500! 23300 detects ground fault current for intermediate station B500 and intermediate station C500. Intermediate stations A, B, and C500 are connected to a master station 600.

FIG. 2 is a circuit diagram of the portion of electrical/optical converter 400 connected to boundary current transformer 300. To explain the circuit configuration, a current transformer 2'f that detects the current flowing through the bond wire 310 etc.
r300 and a circuit 400 that converts the current into an optical signal.

The electrical/optical converter 400 includes a detection resistor Rn and a rectifying resistor R1.
, R2, rectifier diode D, ~D1, light emitting diode PD, , PD, and light emitting diode PD, , po,
The light emitting diode P DI -P Dz, which is composed of a resistor R1 inserted in series with the diodes P DI -P Dz, converts an electrical signal into an optical signal, and detects light with an intensity commensurate with the level of the electrical signal. As shown in the figure, two light emitting diodes P
By connecting D+, F) and I) in series, two optical outputs with the same level and phase can be obtained for the same current. This optical output is sent to two adjacent intermediate stations A and B 500 via optical fiber cables 330, respectively.

Therefore, when the current transformer 300 located at the boundary between sections A and B detects a ground fault current, it appears as a voltage signal across the detection resistor Ro. This voltage signal is rectified by a rectifier circuit consisting of resistors R, SR, and diodes D1 to D4.

The voltage rectified in this way is applied to the light emitting diode PD,
, PD, and resistor R3. This drives the light emitting diodes PD,,pot,
They emit light based on the same drive current. Needless to say, the light emitting diodes PD, , PD, emit light of the same level (intensity) and the same phase. This optical signal is transmitted via an optical fiber cable 330 to intermediate stations A and B5.
The light is received at 00 and photoelectrically converted there. Therefore, when the signal transmitted from the current transformer 200 is stored in the memory recorder using this signal as a trigger, the stored data will have simultaneity between the intermediate stations A and B 500. Therefore, reliable fault location can be obtained by processing data with simultaneity.

FIG. 3 shows a second embodiment of the invention. Portions common to the first embodiment are indicated by common numbers and symbols, so redundant explanations will be omitted.
It has a configuration in which the light is divided into three equal parts by 0, and the divided light is transmitted to intermediate stations A and B 500 via an optical fiber cable 330.

What is important here is that the optical coupler 340 must be adjusted to ensure that it splits and outputs two beams of equal intensity. As a result, data can be stored simultaneously in the same manner as in the first embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects can be expected.

■It is possible to eliminate the phase difference caused by the difference in trigger time between intermediate stations, and it is possible to greatly improve the reliability and accuracy of failure area determination.

■Since it can be divided at intermediate stations, it can be applied to long-distance power transmission lines that cannot be handled with a single optical fiber cable.

(2) In the first embodiment, the electrical/optical conversion circuit includes only one light emitting diode added to the conventional circuit, so there is no need to increase the number of converters or increase the size.

■Since only one current transformer is required to be installed on the line, there is no significant cost increase.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the fault section locating system for underground power transmission lines according to the present invention, and FIGS. 2 and 3 are diagrams showing the first and second electrical/optical converters used in the present invention. The circuit diagram of the embodiment, and FIGS. 4(a) and 4(b) are explanatory diagrams illustrating the principle of a fault section locating system for underground power transmission lines. Explanation of symbols 100...--1--Cable lines 200, 30
0-・-・・−・−・、・Current transformer 310・・・・−1111・・Bond wire 330・−・・−・・−Optical fiber cable 400・−・−−−1− -Electrical/optical converter 500
・−・・−・−−−−1 intermediate station 600−−−1−
−・−・・−Master station R,,R, −R,・−・−−−One resistor DI−D a′−”−′−・−・−Diode PD, PD, SPD,−・・-------1 Light-emitting diode patent applicant Patent attorney Taira 1) Tadao 41- Underground power transmission line 42 Conductor 42a-1 Insulator 43 North 44 Power supply 4611!! Junction 47 Conductor' current・18,・18△7 north'kai'a?1L00
Cable line 200, 300 Current transformer 310 lb cotton 330 Fiber optic cable 400 - Electrical/optical converter 500 Intermediate station 600 Local station Rfi
, R, ~R3 resistance I], ~D, diode PD, PD, , PD, light emitting diode Fig. 4

Claims (2)

[Claims] (1) A plurality of intermediate data processing stations are provided corresponding to a plurality of areas divided in the length direction of the underground power transmission line, and a plurality of intermediate data processing stations are provided in each of the plurality of areas and their boundaries, and a data processing station is provided corresponding to the fault current. a plurality of current detection units that output a fault current signal; an electrical/optical conversion unit that converts the fault current signal into an optical signal and transmits it to the corresponding intermediate data processing station via an optical fiber cable; a central data processing station that locates a fault section of the underground power transmission line based on data processing results of the data processing station; A fault section locating system for an underground power transmission line, characterized in that the optical signal is output to each of the two intermediate data processing stations adjacent to the boundary based on the fault current signal. (2) The underground power transmission line according to claim 1, wherein the electrical/optical converter includes two light emitting diodes connected in series that emit light with an intensity and phase depending on the level and phase of the fault current. failure zone locating system.