JPH0690253B2 - Receiver for accident point exploration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an accident point search receiver.

[Conventional technology]

As a conventional receiver for detecting an accident point, for example, JP-A-59
There has been one using the "signal arrival direction detection device" disclosed in Japanese Patent Publication No. 68678. This conventional device will be described below with reference to the drawings.

Figure 6 is a block diagram of the receiver for this accident point exploration. (1) is an overhead distribution line that seems to have a discharge-induced ground fault, and (4A) and (4B) are on this distribution line (1). An electromagnetic detection antenna for detecting electromagnetic waves emitted by a current traveling wave propagating from an accident point, (5) is a pair of antennas (4
A), (4B) is a receiving device which determines the accident direction from the arrival time difference td of the signals received, and the antenna (4A),
It is connected to (4B) via coaxial cables (6A) and (6B), respectively. The waveform (I) in the figure shows the first wave of the fault current flowing through the distribution line (1).

(9A) and (9B) are absolute value circuits that amplify the input signals output from the antennas (4A) and (4B) and always output positive voltage signals regardless of the polarity of the input signals, (10
A) and (10B) are monostable multivibrators (11A) and (11A) that output a single pulse with a required pulse width Td in synchronization with the rising edges of the output signals of the absolute value circuits (9A) and (9B).
B) is a NAND circuit element in which a flip-flop circuit is configured by connecting the input and output terminals of each other. (12A), (12B)
Is an inverter that outputs a low-level voltage signal when the input signal is a high-level voltage, and outputs a high-level voltage signal when the input signal is a low-level voltage. (13A) and (13B) are LEDs
A signal indicator consisting of an element and its protective resistor, etc., which lights up only when a high level voltage is input from the inverter (12A) or (12B).

Next, the operation of the receiving device (5) will be described.

Assuming now that the antenna (4A) receives the electromagnetic wave earlier than the antenna (4B) by a time difference td, first, the voltage signal output from the antenna (4A) is received via the coaxial cable (6A) as a receiving device ( It is input to the absolute value circuit (9A) in 5), is amplified by this absolute value circuit (9A) and is converted into a positive polarity signal regardless of the polarity of the input signal, and this output signal is output. It is input to the vibrator (10A). The monostable multivibrator (10A) outputs a single-shot pulse of a required time width Td synchronized with the rising of the first wave of this input signal, and this single-shot pulse is input to the NAND circuit element (11A) in the subsequent stage. The NAND circuit element (11A) and the other NAND circuit element (11B) form a flip-flop circuit.
The output voltage of the NAND circuit element (11A) constantly changes from the high level state to the low level, and the NAND circuit element (11B)
This state is maintained for the duration Td of the single pulse output from the monostable multivibrator (10A). The output voltage of the NAND circuit element (11A) is inverted from low level to high level by the inverter (12A) and input to the signal indicator (13A), the signal indicator (13A) is turned on and the direction of the fault point is displayed. To do. continue,
Similarly, when the antenna (4B) receives the electromagnetic wave and outputs a voltage signal, the absolute value circuit (9B) and the monostable multivibrator (10B) are driven, and the NAND circuit element (11B) has a single shot with a time duration Td. A pulse is input, but as described above, NAN
Since the D circuit element (11B) is interlocked with the NAND circuit element (11A) to which the single pulse was input earlier with the time difference of td, the time when the single pulse is input to the NAND circuit element (11A) It is not driven during Td, its output voltage signal is held in a high level state, and the signal indicator (13B) does not light up.

As described above, only the signal indicator (13A) corresponding to the antenna (4A) that received the electromagnetic wave first lights up to indicate the direction of the accident point. Also, when the accident point is located on the side of the antenna (4B), the antenna (4B) receives the electromagnetic wave before the antenna (4A), so contrary to the above, only the signal indicator (13B) lights and the accident point. Display the direction of B.

[Problems to be solved by the invention]

However, in the conventional receiver for detecting an accident point configured as described above, a pair of antennas (4A) and (4A)
If the distance l between B) is a substantial value and l = 3 (m), the minute time difference td of the reception signals of the antennas (4A) and (4B) is 10 ns or less, which is extremely small. Until the time difference Td is expanded to the required time difference, that is, variations in the characteristics of the pair of antennas (4A) and (4B), variations in the amplification factor and response characteristics of the pair of absolute value circuits (9A) and (9B),
Due to variations in the input voltage and switching characteristics of the pair of monostable multivibrators (10A) and (10B), the time difference td between the received signals of the pair of antennas (4A) and (4B) is NA.
There was a problem that the ND circuit elements (11A) and (11B) were reversed at the stage of inputting a single pulse and could be erroneously detected.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a receiver for fault point search capable of more reliably detecting the fault point direction of an overhead distribution line.

[Means for solving problems]

The receiver for accident point exploration according to the present invention includes an antenna for receiving an electromagnetic wave generated from the distribution line due to a ground fault discharge at an accident point in an overhead distribution line, and an output signal of the antenna which is two signals having different polarities. And a half-wave rectifying means for half-wave rectifying the two output signals of the amplifying means, and the half-wave outputs a first-arrival signal of the output signals from the rectifying means and a second-arrival signal. The first-arrival signal prioritizing means for blocking the output of the above is provided.

[Action]

That is, in the present invention, a ground fault discharge is caused at a fault point by a high-voltage pulse applied to the distribution line, and at this time, an electromagnetic wave generated by a current traveling wave propagating through the distribution line from the fault point is emitted, for example, at a charging point. And an antenna located between the accident point and the antenna, the orientation of the antenna with respect to the distribution line is determined so that the polarity of the first wave of the output voltage of the antenna is, for example, negative, and this antenna is set to the accident point. When it is moved toward the side, the polarity of the first wave of the output voltage of the antenna is inverted from negative to positive on the side of the point opposite to the voltage applied from the accident point, and the amplifying means changes the output signal of the antenna to two signals with different polarities. The half-wave rectifying means half-wave rectifies the two output signals of the amplifying means, and the first-arrival signal priority means outputs the first-arrival signal of the outputs from the half-wave rectifying means and blocks the latter-arrival signal output. You By, it is to search the fault point.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. The same reference numerals as those in the conventional example indicate the same or corresponding portions. In Fig. 1, (1) is an overhead distribution line that seems to have a discharge-to-ground fault, and this section is in a power failure state. (3) is an accident equipment such as an insulator or an arrester that has been connected to an unknown point B of this distribution line (1), for example, a discharge ground fault, and the installation point B of this accident equipment (3) is searched. Is what you are trying to do. (2) is a voltage-applying device that intermittently generates high-voltage pulses. It is connected to the distribution line (1) at point A, and one high-voltage pulse is applied to match the discharge start voltage of the accident equipment. The distribution line (1) can be charged until the required voltage is reached. (4) is a loop antenna that receives an electromagnetic wave generated by a current traveling wave propagating from the accident point B on the overhead distribution line (1) and outputs a voltage signal corresponding to a change in the magnetic field of the electromagnetic wave, and (8) is this A receiving device which receives the output voltage of the loop antenna (4) and displays a signal corresponding to the polarity of the first wave of the output voltage of the loop antenna (4), and (6) is the loop antenna (4) and the receiving device. It is a coaxial cable for connecting (8). In addition,
The loop antenna (4), the coaxial cable (6), and the receiving device (8) are mounted on the automobile (7), and the loop antenna (4) has a normal direction of its antenna surface as the traveling direction of the automobile (7). Is installed at a right angle and parallel to the ground.
FIG. 2 is a block diagram of the receiving device (8). In the figure, (14) is an amplifying means for outputting the output signal of the antenna (4) as two signals having different polarities. , Inputs the output voltage of the first inverting amplifier (15A) and the first inverting amplifier (15A) that increases the input voltage at the required amplification rate and inverts and outputs the polarity. It is composed of a second inversion amplifier (15B) that inverts and outputs only the polarity without performing voltage amplification. (16A) and (16B) are the first and second inversion amplifiers (15A) and (15), respectively.
The first and second half-wave rectifying means output the pulse voltage by shaping the output voltage of B) after half-wave rectification. (17) is a first-arrival signal priority means for outputting the first-arrival signal of the output signals from the half-wave rectifying means (16) and blocking the output of the latter-arrival signal. In this embodiment, (17A), (17B)
, D type positive edge trigger type flip-flop circuit elements with reset terminals (hereinafter referred to as D-flip-flop circuit elements) in which the terminals Q and the other terminal D are connected to each other are used. When the output pulse voltages of the half-wave rectifying means (16A) and (16B) are input to T, a voltage signal is output from the terminal Q in synchronization with the rising of these pulse voltages, and the other output is blocked. Has a lock function. That is, of the D-flip-flop circuit elements (17A) and (17B), the one that is input first outputs a voltage signal from its terminal Q and blocks the output from the other terminal Q that is input with a delay. . (18) is the D-flip flip circuit element (17
A reset signal generation circuit for resetting A) and (17B).

Next, the operation will be described. In Fig. 1, the overhead power distribution line (1) in a power failure state is charged by applying a high-voltage pulse with a positive potential at the power supply device (2), and the ground fault is discharged at the accident facility (3), causing an accident. A current traveling wave propagates on the distribution line (1) from the point B toward the voltage application point A and the opposite voltage application point side C. When this traveling wave of current passes through the probe point D near the overhead of the loop antenna (4), an electromagnetic wave is generated from this probe point D, and the loop antenna (4) receives this electromagnetic wave and changes the magnetic field of this electromagnetic wave. The induced voltage corresponding to the minute is output. That is, when the current traveling wave passes through the inspection point D, a magnetic field change occurs around the distribution line (1) in the vicinity of the inspection point D, but the loop antenna (4) passes the distribution line (1). Since it is arranged on a plane including the above, the voltage induced by the change in the interlinkage magnetic flux due to the change in the magnetic field is output. The positive / negative polarity of the first wave of the output voltage of the loop antenna (4) is uniquely determined by the direction of the ground fault current. In this example, however, the distribution line (1) is charged to a positive potential, so The current flows from the point A and the point C on the opposite side to the accident point B. In Fig. 3, a), when the probe point D is on the A side from the accident point B, When the first wave of the output voltage of the loop antenna (4) has a negative polarity as shown in (a) in the figure, (b), when the survey point E is on the side of the point C opposite to the point of charge application from the accident point B, the loop In this embodiment, the loop antenna (4) is arranged so that the first wave of the output voltage of the antenna (4) has a positive polarity as shown by (b) in the figure.

Therefore, if the fault point direction is detected while moving along the overhead distribution line (1) from the side of the charging point A, when the fault point B is passed, the output voltage of the loop antenna (4) The accident point can be searched by reversing the polarity of one wave. The rate of change of the charging current due to the high voltage pulse applied by the power supply device (2) of the distribution line (1) is extremely smaller than the rate of change of the first wave of the ground fault discharge current at the fault point B. Therefore, there is no false detection when a high voltage pulse is applied.

Next, the operation of the receiving device (8) will be described with reference to FIG. FIG. 4 shows the time chart at the input / output end of each block of the receiver (8). The output voltage of the loop antenna (4) is input via the coaxial cable (6) to the first inverting amplifier (15A) that constitutes the amplifier (14) of the receiving device (8), and this inverting amplifier The voltage (amplifier) (15A) boosts the voltage and reverses the polarity at the appropriate magnification and outputs. The polarity of this output voltage is inverted again by the second inversion amplifier (15B) and the result is output. As a result, the output voltages of the inversion amplifiers (15A) and (15B) have the same voltage waveform but different polarities.
This output voltage is the half wave rectification means (16A) in the latter stage,
Half-wave rectification and waveform shaping are performed by (16B) and output as a positive pulse voltage. Taking the case of the search at the search point D in FIG. 3 as an example, the above loop antenna (4)
The first wave of the output voltage becomes negative as shown in Fig. 4 A ₀ , and the polarity of the first wave of the output voltage of the inverting amplifiers (15A) and (15B) is shown in Fig. 4 A ₁ , B ₁ Since the former is positive and the latter is negative as shown in Fig. 4, the half-wave rectifying means (16A) outputs the pulse voltage corresponding to the first wave of the output voltage of the loop antenna (4) as shown in Fig. 4 A ₂ . . This pulse voltage is
Is inputted to the terminal T of the D- flip-flop circuit elements (17A), the circuit element (17A) is by connexion driving the rise of the pulse voltage, shown from the terminal Q of the circuit element (17A) in FIG. 4 A ₃ Output a voltage signal like this and drive the signal indicator (13A) in the subsequent stage with this voltage signal to display the direction of the fault point. By driving the D-flip-flop circuit element (17A), the other D-flip-flop circuit element (17A) is driven.
B) is interlocked, that is, the circuit element (1
The output voltage level of the terminal of 7A) changes from high to low, and this is added to the terminal D of the circuit element (17B). Therefore, the latter half wave rectification means (16B) causes the first wave of the output signal of the loop antenna (4). Even if a pulse voltage is input to the circuit element (17B) as shown in Fig. 4 B ₂ for the second wave of the opposite polarity,
The voltage signal output from the circuit element (17B) is shown in Fig. 4 B ₃
The signal indicator (13B) in the latter stage is not driven as shown in (3). Above D-flip-flop circuit element (17
The output states of A) and (17B) do not change even if the pulse voltage signal is input to each terminal T again, and the reset signal is input to each reset terminal by the operation of the pushbutton switch (18). Held until

The above is an example of exploration at exploration point D in FIG.
At the exploration point E on the side C opposite to the charging point, the direction of the ground fault current flowing through the distribution line (1) is opposite to that at the exploration point D, so that the first wave of the output voltage of the loop antenna (4) is The signal becomes positive (positive) and the signal display (13
B) is driven.

As is clear from the above description, the positive / negative polarity of the first wave of the output signal of the loop antenna (4) is determined by the corresponding D-flip-flop circuit element [(17
A) or (17B)], and a D-flip-flop circuit element [(17
Either B) or (17A)] is blocked. Therefore, the rise time difference td _{2 from} the output signal of the first wave of the loop antenna (4) depends on the pulse voltage output from the half-wave rectifying means (16A), (16B) corresponding to these signals. This is important because it determines the rise time difference, but the time difference td ₂ is shown below.

(A) The resonance frequency of the output signal of the loop antenna (4), which is determined by the inductance of the loop antenna (4) and the capacitance of the coaxial cable (6), is usually 0.5 MHz.
Select in the range of ~ 5MHz.

The time difference td ₂ between the first wave and the second wave of the output signal of the loop antenna (4) is Therefore, for example, when the resonance frequency is 1MHz, td ₂ = 500 (ns), 2MH
At z, td ₂ = 250 (ns).

(B) A stabilizing resistor having an appropriate value is inserted in parallel at the end of the coaxial cable (6), and the loop antenna (4)
If the resonance between the coaxial cable and the coaxial cable does not occur, the second wave having a polarity different from the first wave in the output signal of the loop antenna (4) is generated by the current traveling wave generated by the ground fault discharge. After passing through the exploration point of the high-voltage overhead distribution line (1), it is reflected at the end of the distribution line, and when it passes through the exploration point again, the magnetic field change around the exploration point causes the loop antenna (4).
By receiving. In this case, the time difference td ₂ is the distance L from the search point to the end point in the distribution line (1).
Even if it is only 15m : However, it becomes 100ns from C = 0.3 (m / ns: speed of light), and a sufficiently large time difference is usually obtained.

The time difference td ₂ between the output signal of the first wave of the loop antenna (4) and the output signals of the second and subsequent waves having different polarities is 100 ns or more in both cases (a) and (b) above. In the most practical case (a) above, when the resonance frequency of the loop antenna (4) and the coaxial cable (6) is 1 to ₂ MHz, td ₂ = 250 to 500 ns, while the receiving device (8) The variation in the signal transmission time from the output end of the inverting amplifier (14) to the output end of the pair of half-wave rectification means (16a) (16b) due to the characteristic variation of the components is very small, that is, special consideration. Since the time difference td ₂ in the output signal of the loop antenna (4) can be easily adjusted to 50 ns or less without paying for the signal input stage to the D-flip-flop circuit elements (17a) and (17b). There is no fear of reversing with the loop antenna (4) above. The polarity of the wave of the output voltage reliably be determined.

Further, the conventional example requires two antennas, but this embodiment has an advantage that only one loop antenna is required.

FIG. 5 shows another embodiment. Instead of the second inverting type thickener (15B) in the thickening means (14) in the embodiment of FIG. 2, the input voltage is inverted in polarity. Using a non-inverting amplifier (20) that increases the width without input, and the input device of this non-inverting amplifier (20) is connected in parallel with the inverting amplifier (15A) to the receiver (8).
Connected to the input terminal (A ₀ ) of the
The thickening means (14) is configured by selecting the same thickening rate for the non-inverted thickening device (20) and A).

Therefore, when the output voltage of the loop antenna (4) is input to the receiving device (8), these inverting amplifiers (15A)
Since the non-inversion amplifier (20) outputs voltages having the same waveform but different polarities, the same effect as the embodiment shown in FIG. 2 can be obtained.

Although not shown, the same effect can be obtained by using a video amplifier that widens one input signal and outputs two signals having different polarities.

Further, in each of the above-described embodiments, an example in which a loop antenna is used as an electromagnetic wave receiving antenna is shown, but it is not necessary to limit to a loop antenna as long as it is an antenna of a type that responds to a change in magnetic field, and a ferrite or An antenna in which a conductor is wound around a core made of a magnetic material with high magnetic permeability such as Amorphus can be used.

Furthermore, in the embodiment shown in FIG. 5, the first-arrival signal priority means (17) is provided with a pair of reset terminal JK type positive edge trigger type flip-flop circuit elements (hereinafter referred to as JK).
Although it is different from the embodiment of FIG. 2 in that it is constituted by flip-flop circuit elements) (17C) and (17D), it is clear that the same effect can be obtained in this case as well.

In the above, the D-flip-flop circuit element (17A),
(17B) and JK flip-flop circuit element (17C), (17
All of D) are of the positive edge trigger type, but if an inverter element for inverting the input signal is inserted and used in the preceding stage, the same effect can be obtained even if a negative edge trigger type flip-flop circuit element is used. Is obtained.

Although not shown, the following circuit elements are included in the first-arrival signal priority means.
That is, a pair of RS flip-flop circuit elements and a pair of NANDs that form a flip-flop circuit that receives the output signals of the RS flip-flop circuit elements, respectively.
Circuit element and in this case, the pair of
The RS flip-flop circuit element self-holds and outputs two input signals with a minute time difference.
The ND circuit element outputs the first-arrival signal and blocks the output of the last-arrival signal. It should be noted that this circuit has the D-flip-flop circuit elements (17A) and (1
When used in place of 7B), it is necessary to insert an inverter in the front stage of each RS flip-flop circuit element and in the rear stage of each NAND circuit element in order to match the signal levels at the input and output ends. Also, since the RS flip-flop circuit is equivalent to a pair of NAND circuits that form a flip-flop circuit, a pair of NAND circuit elements can be used in place of the RS flip-flop circuit element, and a pair of the flip-flop circuit that also forms the flip-flop circuit can be used. It is obvious that a single RS flip-flop circuit element may be used instead of the NAND circuit element of.

As yet another example, a pair of monostable multivibrator and a pair of NAND circuit elements forming a flip-flop circuit to which the output pulse signals of the monostable multivibrator are input may be used. The input signal having the time difference is self-holding and outputting the first-arrival signal for a predetermined time determined by the time width of the output pulse signal of the monostable multivibrator, and the output of the last-arrival signal is blocked. In addition, this circuit, in the conventional example shown in FIG.
Since the time difference between the input signals was extremely small (10 ns or less), there was a problem such as erroneous detection, but in the case of the present invention, there is a relatively large time difference between the input signals (for example, 100 ns or more). ， It can be put to practical use enough.

〔The invention's effect〕

As described above, according to the present invention, the direction of the fault point of the high voltage overhead distribution line is detected by the polarity of the first wave of the output voltage of the antenna, the polarity of the first wave of the output voltage is inverted, and the amplification means is used. The output signal of the antenna is output as two signals having different polarities, the two output signals of the amplifying means are half-wave rectified by the half-wave rectifying means, and the first-arrival signal among the outputs from the half-wave rectifying means by the first-arrival signal priority means. Is output and the output of the late arrival signal is blocked, the accident point is searched. Therefore, there is an effect that the accident point can be searched easily, quickly and surely from the ground.

[Brief description of drawings]

FIG. 1 is a conceptual diagram for explaining the accident point search method according to the present invention, FIG. 2 is a block diagram showing a receiver for the accident point search according to the present invention, and FIG. 3 is an explanatory diagram showing the situation of the loop antenna output voltage, FIG. 4 is a time chart showing the operation of each block input / output terminal of the receiver shown in FIG. 2, and FIG. 5 is a block diagram of the receiver for fault point search which is another embodiment, and FIG.
The figure shows a block diagram of a conventional receiver. In the figure, (1) is an overhead distribution line, (2) is a power distribution device, (3) is a ground fault equipment, (4) is a loop antenna, (6) is a coaxial cable, (8) is a receiving device, and (14) ) Is an amplification means, (16) is a half-wave rectification means, and (17) is a first-arrival signal priority means. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Oigawa 5-1-14 Yada Minami, Higashi-ku, Nagoya, Aichi Mitsubishi Electric Corporation Nagoya Works (72) Inventor Shinji Yasuda 5 Yata Minami, Higashi-ku, Aichi Prefecture No. 1-14 Mitsubishi Electric Co., Ltd. Nagoya Works (56) References JP-A-57-3056 (JP, A) JP-B 50-20256 (JP, B2) JP-B 49-39286 (JP, B2)

Claims (11)

[Claims] 1. An antenna for receiving an electromagnetic wave generated from a distribution line due to a ground fault discharge at an accident point in an overhead distribution line, an amplifying means for outputting an output signal of the antenna as two signals having different polarities, A half-wave rectifying means for half-wave rectifying the two output signals of the amplification means, and a first-arrival signal priority means for outputting the first-arrival signal of the output signals from the half-wave rectifying means and blocking the output of the last-arrival signal. A receiver for detecting an accident point characterized by the above. 2. A first amplifying and amplifying device for amplifying an input signal and inverting its polarity and outputting the amplified signal, and an output signal of the first inverting and amplifying device after inverting its polarity. The receiver for detecting an accident point according to claim 1, comprising a second inversion amplifier. 3. The amplifying means comprises an inverting amplifier for amplifying an input signal and inverting the polarity and outputting the amplified signal, and a non-inverting amplifier for amplifying and outputting the input signal. The receiver for accident point search according to claim 1. 4. The receiver for accident point search according to claim 1, wherein the first-arrival signal priority means outputs and holds the first-arrival signal by itself. 5. The receiver for accident point search according to claim 1, wherein the first-arrival signal priority means outputs the first-arrival signal by holding it for a predetermined time. . 6. The first-arrival signal priority means has a pair of D-type flip-flop circuits and a reset signal generating circuit for resetting the flip-flop circuits, and each inverting output terminal of the flip-flop circuit and the other input. The receiver for accident point search according to any one of claims 1 to 3, wherein the receiver is connected to a terminal. 7. The first-come-first-served signal priority means has a pair of JK type flip-flop circuits with reset terminals and a reset signal generation circuit for resetting the flip-flop circuits, and each of the inverted output terminals of the flip-flop circuits. The receiver for accident point search according to any one of claims 1 to 3, wherein the receiving device is connected to the other input terminal. 8. The first-arrival signal priority means has a pair of RS flip-flop circuits, a pair of NAND circuits to which outputs of the flip-flop circuits are input, and a reset signal generation circuit for resetting the flip-flop circuits. ,
An accident point search according to any one of claims 1 to 3, wherein each output terminal of the pair of NAND circuits is connected to the other input terminal of the other. Receiver. 9. The first-come-first-served signal priority means has a pair of monostable multivibrators and a pair of NAND circuits each receiving an output of the monostable multivibrator, and respective output terminals of the pair of NAND circuits. Is connected to the other input terminal on the other side, and the receiver for detecting an accident point according to any one of claims 1 to 3 is characterized in that. 10. The receiver for fault point search according to claim 1, wherein the antenna is a loop antenna. 11. The receiver for detecting an accident point according to any one of claims 1 to 9, wherein the antenna is formed by winding a conductor around a core made of a magnetic material. .