JPH10300809A - Fault current detecting device for transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device easy to construction and also easy to maintain and regulate by detecting a 1-line earth fault by the CT of an overhead earth- wire, and detecting a short-circuit accident by a coil. SOLUTION: A zero phase overcurrent detector 10 detects a 1-line earth fault current when the current value detected by a CT becomes a fixed value or more. A short-circuit current detector IS detects a short-circuit current when even one of voltages of respective coils becomes a fixed value or more. A low voltage detector UV detects that a transmission line is interrupted in an accident when the voltages of detecting bars B1, B2 are suddenly reduced lower than a fixed value. A delay circuit DEL takes the output voltages of the detecting bars B1, B2 as those delayed for 2-3 cycles of commercial frequency, and the outputs are rectangular. Thus, it is prevented that the reference phase in the following vectorization is deviated by the change of the phase of the voltages detected by the detecting bars in an accident. The voltage of a battery E is synchronously rectifying through a synchronous rectifying circuit SYN by the output of the delay circuit DEL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accident current detector for detecting a fault range of a transmission line.

[0002]

2. Description of the Related Art Conventionally, (1) a method of measuring a current at the time of an accident by attaching a CT to an overhead ground wire of a tower, and (2) a method of measuring a current by attaching a coil to a central portion of a tower. There was a method in which a coil and a measuring rod were attached near all the electric wires in the tower.

[0003]

The method of the above (1) is as follows.
The method of (2) has difficulty in detecting both the ground fault current and the short-circuit current, and the method of (3) has a complete detection, but the equipment is complicated, but the construction and maintenance are difficult. , Is difficult to adjust.

[0004]

The present invention provides the above (1).
The advantages of the method of (3) and the advantages of the method of (3) are adopted, and further, the waste caused by the combination is eliminated. One-line ground fault is detected by CT of the ground wire,
The coil detects a short circuit accident. Further, the voltage of the detection rod is obtained through a delay circuit to obtain a reference phase before the accident, and based on the reference phase, all detected voltages and currents are vectorized and temporarily stored as digital signals. The detection of the occurrence of an accident is performed based on the excessive current of the CT and the excessive voltage of the coil, and finally, whether or not to actually transmit the signal is determined by the voltage drop of the electric pole. The receiving side calculates what vector the ground fault current and the short-circuit current have flowed from the power supply, and determines a point where the difference of the fault currents including the phase is the largest in the vector, as the fault section.

[0005]

According to the present invention, one-line ground fault is detected by CT of an overhead ground wire, and short-circuit is detected by a coil. These all take advantage of their features, which allows the coil to
6. The number of test rods is reduced to 2/6, and the error of 10 which has conventionally been a major cause of malfunction is reduced.

[0006]

FIG. Shows a diagram in which a coil and a CT are attached to a steel tower, where 1 is a CT, 2, 3, 4, 5, a coil,
6, 7, 8, 9, 10, 11 are transmission lines, 12,
Is a steel tower. In this figure, the CT of 1 is attached to penetrate the overhead ground wire, and the coils 2, 3, 4, and 5 respectively detect the magnetic fluxes of the electric wires of the transmission line, 6, 8, 9, 11, and 11 effectively. Mounted nearby. The inspection rod is usually
A metal rod insulated with an insulator is mounted on the coils 5, 5, and 4, but when the phases of the electric wires 8 and 11 are different, they are mounted near electric wires of the same phase. 12 is a steel tower. FIG. 2 is a block diagram of the electronic circuit. In this figure,
The CT is a CT attached to an overhead ground wire. C1, C
2, C3 and C4 are coils. This coil catches the magnetic flux of the electric wire on the left and right of the upper arm and lower arm of the electric wire,
It is particularly useful for detecting short-circuit current. B1 and B2 are electric test bars. There are one transmission line, two transmission lines, four transmission lines, and the like, and the power detection rod takes out only one phase voltage of the transmission line. At this time, if there are two or more lines, the voltages of the same phase are all taken out. The number of coils to be attached is the same as that of each line except for one phase. This is because the short-circuit current is sufficient to detect two of the three phases. F1, F2
‥‥ F7 is a filter for adjusting each voltage to an appropriate value, shaping the waveform and removing harmonics. I0 is a zero-phase overcurrent detector. This is to detect that the value of the current detected by the CT has become equal to or more than a certain value, thereby detecting the current of one line ground fault. IS is a short-circuit current detector. This is to detect that at least one voltage of each coil has exceeded a certain value, thereby detecting a short-circuit current. UV is a low voltage detector. This is to detect that the voltage of the power detection rod has suddenly dropped below a certain value, thereby detecting that the transmission line has been cut off at the time of the accident. DEL is a delay circuit, which takes out the output voltages of the detection rods B1, B2 as being delayed by two to three cycles of the commercial frequency. The output is a rectangle.
This prevents the phase of the detection voltage of the detection rods B1, B2 from changing at the time of an accident, and prevents the reference phase from being out of order at the time of the next vectorization. The voltage of the battery E is synchronously rectified by the output of the delay circuit DEL. This synchronous rectification circuit is SYN. E is a battery. Since this battery is charged by a solar cell, it is necessary to constantly monitor the charging voltage. When the voltage of the battery E is synchronously rectified by the output of the delay circuit DEL, the voltage of the battery E is output as a rectangular wave, so that the phase information and the battery voltage information can be included in one signal. VEC is a vectorization circuit. The input is converted into a vector value by an AD converter, converted into a serial signal, and output. This output is sent to the transmission circuit SE.
The transmission side is transmitted in addition to N, and the receiving side determines a faulty section of the transmission line based on the information.

[0007]

According to the present invention, (1) it is possible to easily detect a one-line ground fault by using an overhead ground line which is easy and does not require adjustment. (2) Perform detection with a coil that is easy and reliable to detect a short circuit accident. (3) By the above methods (1) and (2), an inexpensive product can be obtained as a whole, and a device can be easily constructed, and can be easily maintained and adjusted.

[Brief description of the drawings]

FIG. 1 is a structural diagram in which a CT and a coil of the present invention are attached to a steel tower. The description of reference numerals is as follows: 1) CT 2,3,4,5, Coil 6,7,8,9,10,11, {Electric wire 12} Tower installed on overhead ground wire 1 is a block diagram of an electronic circuit according to the present invention. The description of the reference numerals is as follows. CT {CT C1, C2, C3, C4, Coil B1, B2, {Electricity stick I0} ‥‥ Zero-phase overcurrent detector IS ‥‥‥‥‥‥‥‥‥‥‥‥ Short-circuit current detector UV ‥‥‥‥‥‥‥‥‥‥‥‥ Low-voltage detector DEL ‥‥‥‥‥‥‥ ‥‥‥‥ Delay circuit SYN ‥‥‥‥‥‥‥‥‥‥‥ Synchronous rectification circuit VEC ‥‥‥‥‥‥‥‥‥‥‥ Vectorization circuit SEN ‥‥‥‥‥‥‥‥‥‥‥ Transmission circuit E ‥‥‥‥‥‥‥‥‥‥‥‥‥ battery

Claims (3)

[Claims] 1. A current transformer (hereinafter referred to as CT) is attached to an overhead ground wire of a power transmission tower, and coils are mounted near the upper arm and lower arm wires of the tower, respectively, and are insulated by insulators. A fault current detector for a transmission line, characterized in that conductors are attached to the tower at locations close to wires of the same phase. 2. When at least one of an excessive current flowing through the CT, an excessive voltage of each coil, and a voltage drop of each detection rod is detected, the vectorization circuit is activated and the CT current is detected. And, the fault current detector of the transmission line which vectorizes the voltage of each coil and the voltage of each inspection rod, digitizes the maintenance signal at the same time, temporarily stores it and sends it when a power outage of the transmission line is detected. 3. The fault current detector of a transmission line, wherein the voltage of each power detection rod is added to form a rectangular wave, and then delayed for three cycles or more of a commercial frequency and used as a reference phase for vectorization. .