JP2645703B2 - Transmission line fault point detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

 The present invention relates to an apparatus for detecting an accident point on a transmission line.

[Prior art]

As a method of detecting the fault point of the transmission line, a plurality of light output type converters (hereinafter referred to as optical CTs) are provided through predetermined locations on the overhead ground wire, and the light emitting diodes (LEDs) of the optical CTs emit light. Is received by a photodiode via an optical fiber, is converted into an electrical signal by the photodiode, and the phase of the electrical signal is compared by a phase determination circuit to determine a position of a faulty tower or a faulty section of a transmission line. It has been proposed (JP-A-57-46622).

[Problems to be solved by the invention]

Since this optical CT is provided on an overhead ground wire, it is used under extremely severe conditions both in terms of weather and electrically, but high reliability is required for this optical CT. However,
In the detection device according to this proposal, the judgment circuit functions only when a large current flows through the overhead line due to an accident, and does not function at all in normal times. There was a drawback that could not be found. Therefore, in an accident point detector for an overhead ground line with a very low incidence of accidents, optical CT
There was a need for a means of confirming that the data was normal. In the accident point detecting device according to the present invention, the fault point is detected based on the phase of the current of the overhead ground wire obtained by the plurality of current detecting means provided on the overhead ground wire, whether or not the current detecting means is operating normally. It is an object of the present invention to improve the reliability of the operation of the accident point detecting device by constantly monitoring whether or not it is.

[Means for Solving the Problems]

The fault point detection device according to the present invention is a current detection device with a rated capacity that is magnetically saturated with a large current flowing through an overhead ground wire at the time of an accident, and that a small current flowing constantly in normal times can be detected within a linear detection range. Means (1) and an electric / optical conversion means (4) for outputting a detection signal of the current detection means (1) as an optical signal, and two optical CTs respectively provided on overhead ground lines on both sides of the power transmission tower; Two optical / electrical conversion means (8) for respectively converting the optical signals output from the optical CT into electric signals; and in the event of an accident, the two optical / electronic By determining whether the phase difference of the pulse signal output from the conversion means (8) is equal to or greater than a predetermined value,
A phase judgment circuit (10) for judging whether or not a transmission line accident has occurred at the transmission tower;
Schmitt for integrating a signal output from the power conversion means (8) by an integration circuit and outputting a pulse when the integrated value exceeds a predetermined level or every time a signal of a predetermined level is input. A monitor circuit (11) for supplying to the trigger circuit and determining that the optical / electrical conversion means (8) and the optical CT are functioning normally when a pulse is output from the Schmitt trigger circuit; It is characterized by.

[Action]

As described in the above-mentioned publication, if a large current of an accident is detected within a linear detection range (that is, a large rated capacity is used) by a current detection means, a small current flowing in a normal state cannot be detected. . When carefully examined here, it is not necessary to faithfully detect the waveform of the large current of the accident, but only the phase at the time of occurrence. Therefore, the fault point is determined by determining the phase of the pulse output for magnetic saturation by using the current detecting means (1) having a small rated capacity and determining the fault point. A small current that is constantly flowing is detected within the linear detection range by the current detection means (1), and the presence or absence of the detection signal (for example, whether or not the integrated value of the detection signal exceeds a predetermined level) is determined. By performing the detection, it is possible to monitor whether the circuit of the optical CT including the current detecting means (1) is functioning normally.

【Example】

FIG. 1 shows an embodiment of the present invention. An overhead ground wire 2 passes through the current transformer 1, and an output of the current transformer 1 is input to an input unit of the LED drive unit 3. An LED 4 is connected to the output side of the LED drive unit 3. The light entrance 6 of the optical fiber 5 is arranged to receive the light of the LED 4. The photodiode 8 is arranged so that light from the light emitting section 7 of the optical fiber 5 can enter. The signal converted from the optical signal to the electric signal by the photodiode 8 is input to an input section of an amplifier 9, and the signal amplified by the amplifier 9 is input to a phase determination circuit 10 and a monitor circuit.
11 is input to each. The output of the monitor circuit 11 and the output of the phase determination circuit 10 are input to a transmission device 12, from which various command signals are output based on the detection results. In the above configuration, the current transformer 1, the LED driving unit 3, and the L
The circuit composed of ED4 is the optical CT. A pair of such optical CTs is provided on each side of the power transmission tower on an overhead ground wire, and a phase determination circuit 10 and two monitor circuits 11 are provided for the pair of optical CTs. The operation of the device having the above configuration will be described below. When a ground fault occurs in a transmission line, a ground fault current of several hundred A flows through the overhead ground fault as shown in FIG. The magnitude of this current can be obtained by calculation from the line constant of the transmission line. The rated capacity of the current transformer 1 is selected so that the current transformer 1 is magnetically saturated when the ground fault current flows.
Therefore, when a ground fault current flows through the overhead ground wire 2, the output of the optical CT becomes a pulse as shown in the lower diagram of FIG. 5 due to the magnetic saturation of the current transformer 1. The output is sent to the phase determination circuit 10 via the amplifier 9. By the way, when a ground fault of a transmission line occurs at a transmission tower, the fault current at that time flows as a ground fault current through the tower, but since the ground resistance of the tower itself is not zero, a part of the fault current is It flows to the tower on both sides through the line. Even in the tower into which the fault current flows, since the ground resistance of the tower is not zero, a part of the tower further flows through the overhead ground wire. Thus, the direction of the current flowing through the overhead ground wire on both sides is opposite (180 ° phase difference) in the tower where the accident occurred, but the current flowing through the overhead ground wire on both sides is the same in the non-accidental tower. Direction (phase difference 0 °). Therefore, the direction of the ground fault current passing through the current transformer 1 is known by comparing the phase of the pulse obtained from the photodiode 8 corresponding to each optical CT by the phase determination circuit 10, and thereby, the fault point can be determined. Can be oriented. The signal output by the phase determination circuit 10 is input to the transmission device 12, and the transmission device 12 outputs a desired command signal. For example, as shown in FIG. 2, the phase determination circuit 10 includes a gate 21 for selectively passing a detection signal output from each amplifier 9 to a subsequent stage, and when a detection signal is output from each gate,
A one-shot multivibrator 22 that outputs a pulse of a fixed width, a phase comparison circuit 23 that compares the phase difference between the pulses output from both wasshot multipipulators 22,
A determination output circuit that outputs a pulse indicating that a power transmission line accident has occurred in the tower when the phase difference is equal to or greater than a predetermined location (eg, 120 °); The phase comparison circuit 23 can be implemented using a counter that counts clocks. In the present embodiment, when a pulse is input from one one-shot multivibrator 22, another one-shot multivibrator, for example, outputs a signal of 120 °. A pulse having a width is output, and this pulse and the pulse from the other one-shot multivibrator 22 are supplied to the AND gate.If the phase difference between the pulses from both the one-shot multivibrators 22 is within 120 °, , And a high signal is output from the AND gate. When one pulse is output from the one-shot multivibrator 22, the next pulse is output only after one cycle has elapsed, so that the one-shot multivibrator 22 does not detect the nozzle during that time. When a pulse is output from the multivibrator 22, the gate circuit 21 is closed for a predetermined time. In addition, when an accident occurs, as shown in FIG. 5, power transmission is interrupted within three cycles, and then, after 10 to 20 cycles, power is retransmitted. Each time the output circuit 24 performs the determination operation, the gate circuit 21 is closed. Next, a description will be given of a monitor circuit for monitoring whether or not the optical CT is normal, which is the gist of the present invention. Even in normal times when the ground fault does not occur on the transmission line, the dielectric current of the transmission line or the charging current to the ground due to insufficient mounting of the transmission line always flows through the overhead ground line 2 with a magnitude of several A. The present invention focuses on this current. As shown in the lower diagram of FIG. 5, the output waveform of the optical CT in the normal state is a half-wave rectification of the primary current of the current transformer 1, that is, the current of the overhead ground wire 2 (the LED has a current when flowing in one direction). Therefore, if such a half-wave rectified waveform is output from the amplifier 9, the amplifier 9 and the optical CT circuit connected to it are functioning normally. The monitor circuit 11 is provided in order to know this, and to know this. As shown in FIG. 3, the monitor circuit 11 integrates an output of the amplifier 9 and outputs a High level signal when the level of the integrated output signal of the integration circuit 11a exceeds a threshold value, as shown in FIG. And a comparison circuit 11b. A small current flowing through the overhead ground wire in normal times is detected by the optical CT, and its signal is integrated by the integrating circuit 11a of the monitor circuit 11 through the amplifier 9, and the integration result exceeds the threshold value. A high-level signal is output, and when the high level is input to the transmission device 12, the transmission device 12 outputs a signal indicating that the optical CT is functioning normally. If a failure occurs in any of the components of the light CT, for example, when the LED 4 stops emitting light, the output of the amplifier 9 disappears and the integral output of the integrating circuit 11a does not occur. Therefore, the output of the comparison circuit 11b becomes Low level, thereby
You can know the failure. Here, in the monitor circuit 11, in order to detect that a half-wave rectified signal (the output level becomes 0 intermittently) is output from the amplifier 9, the output signal of the amplifier 9 is integrated into the integrating circuit 11.
Although the integration is performed at a and it is determined whether or not the integrated value exceeds a predetermined level, the integration may be realized by a Schmitt trigger circuit without using the integrator 9. That is, as shown in FIG. 4, if a Schmitt trigger circuit that outputs a pulse every time a signal exceeding a predetermined level is input is used as the monitor circuit 11, a Schmitt trigger circuit is output every time a half-wave signal is input. Output a pulse H, while the pulse H is output, the light CT
Is normal.

【The invention's effect】

As described in detail above, the present invention provides an accident point detection device that determines an accident point based on output signals of current detection means provided at a plurality of locations on an overhead ground wire, using a current detection means having a small rated capacity, For a large fault current, the fault point is determined by determining the phase of the pulse output for magnetic saturation, and for a small current that is constantly flowing in normal times, the current detection is performed. Means is detected within the linear detection range, and whether or not the detection signal is actually detected is checked to check whether or not the apparatus is functioning normally. In some types of detection devices, except for the uneasiness of whether the operation of the current detection means is functioning normally,
The reliability of the accident point detection operation can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing an example of a phase determination circuit used in the embodiment of FIG. 1. FIG. 3 and FIG. 4 are embodiments of FIG. FIG. 5 is a waveform diagram showing a primary current waveform of a current transformer and an output waveform of an optical CT. 1... A current transformer 2... An overhead ground wire 4. ... Photodiode 9 ... Amplifier 10 ... Phase judgment circuit 11 ... Monitor circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaru Ihara 1-3-1 Shimaya, Konohana-ku, Osaka City Inside Sumitomo Electric Industries, Ltd. Osaka Works (72) Koichi Hibayashi 1-1-1, Shimaya, Konohana-ku, Osaka-shi No. 3 Sumitomo Electric Industries, Ltd., Osaka Works (72) Inventor Yuji Kimura 950, Kazatori-cho, Kumatori-cho, Sennan-gun, Osaka Sumitomo Electric Industries, Ltd., Kumatori Works (56) References JP-A-57-46622 Shokai Sho 57-3335 (JP, U)

Claims (1)

(57) [Claims] A current detecting means having a rated capacity capable of detecting a small current which is magnetically saturated by a large current flowing through an overhead ground wire at the time of an accident and constantly flowing in a normal state within a linear detection range; An optical / optical conversion means (4) for outputting a detection signal of the current detection means (1) as an optical signal, and two optical CTs respectively provided on overhead ground wires on both sides of the power transmission tower.
And two optical / electrical converting means (8) for respectively converting the optical signals output from the optical CT into electric signals; and in the event of an accident, the two optical / optical converting means by magnetic saturation of the current detecting means. A phase determination circuit (10) determines whether or not a transmission line accident has occurred in the power transmission tower by determining whether or not the phase difference between the pulse signals output from the power conversion means (8) is equal to or greater than a predetermined value. And when a small current flows through the overhead ground wire in normal times, the signal output from the optical / electrical conversion means (8) is integrated by an integrating circuit,
When the integrated value is above a certain level, or
The signal is supplied to a Schmitt trigger circuit that outputs a pulse every time a signal of a predetermined level is input, and when a pulse is output from the Schmitt trigger circuit, the light /
A fault detecting device for a transmission line, comprising: a power conversion means (8) and a monitor means (11) for determining that the optical CT is functioning normally.