JPH0573184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an overhead distribution line fault point detection device that applies high voltage pulses to search for discharge ground fault points in overhead power distribution lines.

[Conventional technology]

As a conventional fault point detection device for overhead distribution lines,
For example, there is one that utilizes the "signal arrival direction detection device" disclosed in Japanese Patent Application Laid-Open No. 59-68678. This conventional device will be explained with reference to the drawings.

Figure 6 is a block diagram of this fault point detection device, where (1) is an overhead distribution line where a discharge ground fault appears to have occurred, and 4A and 4B are the fault points propagated on this distribution line 1 from the fault point. An electromagnetic wave detection antenna 5 for detecting electromagnetic waves emitted by an incoming current traveling wave is a receiving device, and is connected to the antennas 4A and 4B via coaxial cables 6A and 6B, respectively. Note that waveform I in the figure indicates the first wave of fault current flowing through the distribution line 1.

9A and 9B are antennas, absolute value circuits that output positive polarity voltage signals in response to signal input from 4A and 4B, and 10A and 10B are absolute value circuits 9A and 9B.
A monostable multivibrator that outputs a single pulse of the required pulse width T _d in response to a signal input from
1A and 11B are NAND circuit elements whose input and output terminals are connected to each other to form a flip-flop circuit. 12A and 12B are inverters that invert the signal level of the input signal and output it; 13A and 13B
is a signal indicator.

Next, the operation of this receiving device 5 will be explained with reference to the time chart shown in FIG.

Now, antenna 4A has a time difference from antenna 4B.
Assuming that the above electromagnetic wave is received td first, first the A ₀ in Fig. 7 output from the antenna 4A.
A voltage signal as shown in FIG. 7 is input to the absolute value circuit 9A, and the voltage signal as shown in FIG.
In response to a signal as shown in _A1 , the monostable multivibrator 10A outputs a single pulse with a required time width T _da as shown in FIG. _7A2 . By inputting this single pulse, the NAND circuit element 11B is interlocked and the NAND circuit element 11B is interlocked.
A outputs an output signal as shown in FIG. 7 _A3 for the time width T _da of the above input pulse, and
A causes the signal to be inverted as shown in FIG. _7A4 , lighting up the signal display 13A and indicating the direction of the accident point. Subsequently, when the antenna 4B receives the electromagnetic wave and outputs a voltage signal, it operates in the same way, and the monostable multivibrator 10B sends a single pulse with a time width T _db to the NAND circuit element 11B as shown in FIG. _7B2 . is input, but as above,
NAND circuit element 11B is NAND circuit element 11A
Since it is interlocked by
During the time period T _da during which the single pulse is input to the NAND circuit element 11A, it is not driven, and therefore the signal indicator 13B is not input and does not light up.

[Problem that the invention seeks to solve]

_{However ,} in the conventional fault point detection device for overhead distribution lines configured as described above, the signal indicator is
After normally displaying for T _da , the other signal display 13B incorrectly displays for (t _d + T _db - T _da ), but the time widths T _{da and} T of the respective output pulse signals of the monostable multivibrators 10A and 10B Due to variations in the capacitance and resistance values used to set db and changes over time, it is difficult to set and maintain T _da = T _db . Therefore, the above-mentioned incorrect display time becomes a value _that cannot be ignored. There were problems such as misjudgment of the direction of the accident point.

This invention has been made in order to solve the above-mentioned problems, and aims to provide a fault point detection device for overhead power distribution lines that can prevent false indications on the other signal display after a normal display on one signal display. purpose.

[Means for solving problems]

A fault point detection device for an overhead power distribution line according to the present invention includes a high voltage pulse applying means that intermittently applies a high voltage pulse to an overhead power distribution line in a power outage state to cause a ground fault discharge at a fault point; An antenna that receives electromagnetic waves emitted by a traveling current wave from an accident point, a time difference signal output means that outputs a time difference signal based on the output signal of this antenna, and a first-arrival signal of the output signals of the time difference signal output means that is continuously outputted. and a first-arriving signal holding means for preventing the output of the second-arriving signal, a signal display means for displaying the direction of the accident point with respect to the position of the antenna by the output of the first-arriving signal holding means, and a reset means for resetting the first-arriving signal holding means. This configuration includes signal generating means.

[Effect]

In the fault point detection device for an overhead power distribution line according to the present invention, the time difference signal generating means first outputs a signal corresponding to the direction of the fault point on the power distribution line, albeit for a short time,
The first-arriving signal holding means which receives these output signals as input holds the first-arriving signal and outputs a continuous signal, and also blocks the output of the second-arriving signal. In addition to displaying the point direction, the first arrival signal holding means is reset by inputting the output signal of the reset signal generating means after an arbitrary time, and the operation of the signal displaying means is stopped.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Note that the same reference numerals as in the conventional example indicate the same or corresponding parts. In Figure 1, 1 is an overhead power distribution line where a discharge ground fault appears to have occurred, and this section is in a power outage state. 3 is the faulty equipment, such as an insulator or arrester that caused a discharge ground fault, which was connected to the unknown point B of this distribution line 1, and the purpose is to investigate the installation point B of this faulty equipment 3. . Reference numeral 2 denotes a high voltage pulse application means (power charging device) that generates high voltage pulses intermittently, and is connected to the above distribution line 1 at point A, and the application of one high voltage pulse starts the discharge of the accident equipment. The distribution line 1 can be charged until the required voltage corresponding to the voltage is reached. 4A and 4B are electromagnetic wave detection antennas that detect electromagnetic waves emitted by traveling current waves propagating from the fault point on the distribution line 1. Usually, a loop antenna is used, and the antennas are separated by an appropriate distance l (m). , for example, is installed on the roof of the automobile 7 in series with the direction of movement of the automobile 7. 8 is a receiving device that determines the direction of the accident point from the arrival time difference td of the signals received by the pair of antennas 4A and 4B, and is connected to the antennas 4A and 4B via coaxial cables 6A and 6B, respectively. It is installed in car 7. Note that waveform I in the figure is distribution line 1.
This shows the first wave of fault current flowing through the circuit.

FIG. 2 is a block diagram of the receiving device 8.
9 inputs the output signals of antennas 4A and 4B and
This is a time difference signal output means that outputs a signal having a time difference between two signals, and in this embodiment, it is composed of absolute value circuits 9A and 9B that amplify the input signal and always output a positive polarity voltage signal regardless of the polarity of this input signal. has been done. 14A and 14B are inverters that waveform-shape the output signals of these absolute value circuits 9A and 9B and invert the high and low levels and output them, and 15 is the above-mentioned time difference signal that is inputted via these inverters 14A and 14B. It is a first-arriving signal holding means that continuously outputs the first-arriving signal among the output signals of the output means 9 and blocks the output of the later-arriving signal, and in this embodiment, the inverter 14 shown at 16A and 16B
R is set by inputting the low-level voltage signals of A and 14B to the respective input terminals, and outputs a high-level voltage signal from the output terminal Q while self-holding the input signal until a reset signal is input to the terminal. -S flip-flop circuit element and a pair of NAND circuit elements 11 forming a flip-flop circuit that receives the output signals of these as inputs, respectively.
It is composed of A and 11B.

13 is a signal display means for displaying the direction of the accident point;
This embodiment is composed of signal indicators 13A and 13B consisting of LED elements and their protective resistors, etc., and lights up only when a high level voltage is input from the inverter 12A or 12B.

17 is a reset signal generating means for resetting the first-arrival signal holding means 15;
Input the outputs of circuit elements 11A and 11B
AND circuit element 18 and a monostable multivibrator 19 which, by inputting the low-level voltage signal of this AND circuit element 18, is triggered by the rising edge of this input signal and outputs a single pulse signal with a time width T _e . By inputting the output pulse signal of this monostable multivibrator 19, a monostable multivibrator 20 that is triggered by the falling edge of the trailing edge of this input pulse signal and outputs a single pulse of time width T _r , and a manual reset manual reset switch 21, and this manual reset switch 2.
1 and an AND circuit element 22 which inputs the output signal of the monostable multivibrator 20, and the output terminal of this AND circuit element 22 is connected to the R-S flip-flop circuit elements 16A, 16B.
Connect to the reset terminal of

The monostable multivibrator 19 is provided with a variable resistor 23 and a capacitor 24 for arbitrarily setting the time width T _e of the output pulse signal, and the monostable multivibrator 20 is provided with a variable resistor 23 and a capacitor 24 for setting the time width T e of the output pulse signal. A resistor 25 and a capacitor 26 are provided to set _r to an appropriate value. In the figure, Vcc indicates the power supply of the circuit.

Next, the operation will be explained. In FIG. 1, the overhead power line 1 in a power outage state is charged by applying a high voltage pulse with the high voltage pulse application means (power charging device) 2, and when the faulty equipment 3 causes a ground fault discharge, the above-mentioned distribution line 1 is charged. A ground fault current due to the charged charges flows into the fault point B. The rise of the first wave of the transient current in this ground fault discharge is generally very steep, and the current travels along the distribution line 1 from the fault point B in the direction of the energized point A and the opposite energized point side C. propagate. A car 7 equipped with a pair of antennas 4A, 4B and a receiving device 8 runs parallel to the overhead power distribution line 1 directly below the power distribution line 1 from a charging point A toward a non-powering point C. Assuming that the electromagnetic waves emitted from the current traveling wave propagating through the distribution line 1 are received by the antennas 4A and 4B when the antenna is located at an arbitrary point D between the energizing point A and the fault point B. In this case, the antenna 4A on the side of the accident point B receives the signal first, and the other antenna 4B receives the signal with a delay of the time difference td. If the distance between antennas 4A and 4B is l=3(m), then the time difference td is td=l/C=3(m)/0.3
(m/ns) = 10 (ns) (C: speed of light 0.3 m/ns), but since electromagnetic waves usually arrive from the direction above the antenna's inclination, the actual time difference is shorter than the above calculation, less than 10 ns. It is. When the vehicle 7 is located on the opposite charging point side C from the accident point B, the antenna 4
When antennas A and 4B receive the electromagnetic waves, the rear antenna 4B, that is, on the accident point B side, receives the electromagnetic waves earlier than the other antenna 4A by a time difference td. Therefore, among the pair of antennas 4A and 4B,
By determining which of the electromagnetic waves emitted by the current traveling wave propagating from the fault point is received first, the direction of arrival of the current traveling wave, that is, the direction of the fault point can be detected. Since the direction of the accident point can be detected every time the power applying device 2 applies a high voltage pulse intermittently, the direction of the fault point can be detected by the antenna 4 as described above.
If a car 7 equipped with A, 4B and a receiver 8 is driven from the charging point 2 along the overhead power distribution line 1 while detecting the direction of the accident point, the antenna that receives the electromagnetic waves first will receive the electromagnetic waves from the antenna 4A. By changing to the antenna 4B, the ground fault point B can be detected.

This operation will be explained in detail below with reference to FIGS. 2 and 3. In other words, it is assumed that a vehicle 7 equipped with antennas 4A, 4B, a receiving device 8, etc. is located near a point D between a charging point A and a ground fault point B, and the signal propagates through the distribution line 1 from the ground fault point B. Assuming that the antenna 4A receives the electromagnetic waves generated by the traveling current waves earlier than the antenna 4B by a minute time difference td (for example, 10 ns), the antennas 4A and 4B receive the electromagnetic waves A ₀ , B ₀ in Fig. 3. A signal as shown in is output.
From the absolute value circuits 9A and 9B that constitute the time difference signal output means 9 by inputting these output signals, as shown in FIG.
A signal with a time difference td that has been amplified and converted to positive polarity as shown in A ₁ and B ₁ is output, and the inverter 14
A, 14B, as shown in FIG. 3 _A2 , _B3 , the R-S flip-flop circuit element 16A, which is waveform-shaped and inverted and constitutes the first-arrival signal holding means 15;
16B is input to each input terminal. R
-S flip-flop circuit elements 16A and 16B are set by inputting a low-level voltage signal, hold this input signal and output from output terminal Q as shown in _FIG .
A high-level voltage signal as shown in _B3 is output, and this signal is input to the NAND circuit elements 11A and 11B, respectively. These NAND circuit elements 11
Since the input signals of A and 11B have a time difference of td, the NAND circuit 11A to which the first-arrival signal is input operates and outputs a low-level voltage signal to the inverter 12A, as shown in FIG. _{3 A4} and B4. A high level voltage signal as shown in FIG. 3 A5 is input to the signal display 13A constituting the signal display means 13, and the signal display 13A lights up to indicate the direction of the accident point. Next, a late arrival signal was input.
Since the NAND circuit element 11B is interlocked with the NAND circuit element 11A, which is already activated by the input of the first-arrival signal, it does not output (high level state) as shown in FIG. The signal display 13B is not inputted and does not light up as shown in FIG. 3B5. The output states of the NAND circuit elements 11A and 11B do not change even if signals are input again to the respective input terminals of the R-S flip-flop circuit elements 16A and 16B, and the output states of the NAND circuit elements 11A and 11B do not change even if signals are input again to the respective input terminals of the R-S flip-flop circuit elements 16A and 16B. It is held until a reset signal is input.

Next, the operation of the reset signal generating means 17 will be explained. The above TNAND circuit elements 11A, 11 are connected to the input terminal of the monostable multivibrator 19.
When the output signal (low level voltage) of B is input through the AND circuit element 18, the monostable multivibrator 19 outputs from the output terminal Q due to the falling edge of the input signal as shown in FIG. 3 _C2. A high-level voltage pulse signal having a predetermined time width T _e is output, and this signal is input to the input terminal of the monostable multivibrator 20 . Due to the fall of the trailing edge of this input signal, this monostable multivibrator 20 has a time width T _r as shown in _FIG .
Outputs a low-level voltage pulse signal. This signal is input to the terminals of the R-S flip-flop circuit elements 16A and 16B via the AND circuit 22, and the R-S flip-flop circuit element 1
6A and 16B are reset at the same time. Therefore, unlike the conventional example, for example, after the signal display 13A normally lights up and displays, the other signal display 13B lights up momentarily and causes an erroneous display, which does not occur at all. The lighting display time of the signal indicator 13A or 13B is determined by the operating time from setting to reset of the R-S flip-flop circuit elements 16A, 16B, that is, the time width T _e of the output pulse signal of the monostable multivibrator 19. but,
This time width T _e can be arbitrarily set using a variable resistor 23 external to the monostable multivibrator 19 . The time width T _r of the output pulse signal of the monostable multivibrator 20 is set to a sufficient time (for example, several milliseconds) to reliably reset the R-S flip-flop circuit elements 16A, 16B. Note that the R-S flip-flop circuit elements 16A, 16 are manually operated by operating the switch 21.
B can be reset at any time.

FIG. 4 shows another embodiment, in which the first-arrival signal holding means 15 is constructed using a pair of D-type negative edge trigger type flip-flop circuit elements 31A and 31B (hereinafter referred to as D-flip-flop circuit elements) with reset terminals. , each inverting output terminal is connected to the other input terminal D, and the clock input terminal is used as an input terminal. A pair of monostable multivibrators 10A, 10B and a NAND circuit element 11 forming a flip-flop circuit
A and 11B are inserted. Furthermore, the reset signal generating means 17 is replaced with an OR circuit element 18 in the reset signal generating means 17 in the above embodiment.
It is constructed using circuit elements 32.

FIG. 5 shows a receiving device 8 of the embodiment shown in FIG.
The time charts at the input and output terminals of each circuit block are shown. The feature of this embodiment is that the absolute value circuits 9A and 9B constituting the time difference signal generating means 9 output minute time differences td as shown in _{FIG .}
(for example, 10ns or less) to NAND circuit element 11A, 1
At the output stage of 1B, _the time difference T _d (for example, several _ms ) is expanded as shown in FIG. is activated by the falling edge of the leading edge of this input signal, and A ₄ , B ₄ in Fig. 5
As shown in the figure, the first-arrival signal is securely held,
The purpose is to prevent the output of late arrival signals. And these D-flip-flop circuit elements 31A, 3
By inputting one of the high level output signals of 1B to the terminal B of the monostable multivibrator 19 through the OR circuit element 32, C ₂ , As shown in C ₃ ,
After a time corresponding to the time width T _e of the output pulse signal of the monostable multivibrator 19 (which can be arbitrarily set using the variable resistor 23), a low level pulse signal with a time width T _r is output from the monostable multivibrator 20.
The signal is input to the D-flip-flop circuit elements 31A and 31B through the AND circuit element 22, and these circuit elements 31A and 31B can be simultaneously reset to an arbitrarily set time. Therefore, this embodiment also has a signal indicator (either 13A or 13B) like the above embodiment shown in FIG.
After the display is completed normally, the other signal display (13
B, 13A) will not be displayed erroneously for a moment, and the display time can be set arbitrarily.

In addition, in the embodiment shown in FIG. 2, the first-arrival signal holding means 15 is composed of a pair of R-S flip-flop circuit elements 16A, 16B and a pair of NAND circuit elements 11A, 11B, but the R-S flip-flop circuit Since it is equivalent to a pair of NAND circuits that constitute a flip-flop circuit, R-S
Four NAND circuit elements (not shown) are used in place of the flip-flop circuit elements 16A and 16B.
It is possible to configure and use a pair of R-S flip-flop circuits, and similarly, one R-S flip-flop circuit (not shown) may be used in place of the pair of NAND circuit elements 11A and 11B. it is obvious. Furthermore, in place of the R-S flip-flop circuit elements 16A and 16B, a set terminal of a D-flip-flop circuit with a set terminal, a reset terminal, a J-K flip-flop circuit, or any other master-slave type R-S flip-flop circuit can be used. A similar effect can be obtained by using it as an input.

Furthermore, in the first-arrival signal holding means 15 in the embodiment shown in FIG. 4, instead of the D-flip-flop circuit elements 31A and 31B, in the case of FIG. It is clear that the same effect can be obtained by using the same method (not shown). If a positive edge trigger type is used as the D-type or J-K type flip-flop circuit element in the embodiment shown in FIG. A similar effect can be obtained by inserting .

In each of the embodiments described above, a loop antenna is used as an antenna for receiving electromagnetic waves. However, it is not necessary to limit the antenna to a loop antenna as long as it is a type of antenna that responds to changes in the magnetic field. It is possible to use an antenna in which a conductor is wound around a core made of a magnetic material with high magnetic permeability.

〔Effect of the invention〕

As described above, according to the present invention, the first-arriving signal holding means holds the first-arriving signal indicating the direction of the fault point among the two signals with a slight time difference outputted by the time-difference signal output means to the fault point detection device for overhead distribution lines. Since the first-arrival signal holding means is configured to be outputted continuously and to prevent the output of the last-arriving signal, and to reset the first-arrival signal holding means to an arbitrary time using the reset signal outputted by the reset signal generating means, it is possible to avoid momentary erroneous display. This problem is solved, and the direction of the accident point can be accurately recognized using the signal display means.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the concept of a fault point detection device for overhead distribution lines according to the present invention, FIG. 2 is a block diagram showing an embodiment of the fault point detection device used in the present invention, and FIG. A time chart showing the operation of the input/output terminals of the receiving device shown in the figure, FIG. 4 is a block diagram showing another embodiment of the accident point searching device used in the present invention, and FIG. 5 is a receiving device shown in FIG. 4. A time chart showing the operation of the input and output terminals of the device, FIG. 6 is a block diagram showing a conventional receiving device, and FIG.
3 is a time chart showing the operation of the input and output terminals of the receiving device shown in the figure. In the figure, 1 is an overhead power distribution line,
2 is a high voltage pulse application means (power charging device), 3 is ground fault equipment, 4, 4A, 4B are loop antennas,
8 is a receiving device, 9 is a time difference signal output means, 13 is a signal display means, 15 is a first-arrival signal holding means, and 17 is a reset signal generating means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. High voltage pulse application means that intermittently applies high voltage pulses to an overhead power distribution line in a power outage state to cause a ground fault discharge at a fault point, and a current traveling wave from the fault point of the distribution line is An antenna that receives emitted electromagnetic waves, a time difference signal output means that outputs a time difference signal based on the output signal of this antenna, and a system that continuously outputs first-arriving signals among the output signals of this time difference signal output means and blocks the output of later-arriving signals. It is characterized by comprising a first-arrival signal holding means, a signal display means for displaying the direction of the accident point with respect to the position of the antenna based on the output of the first-arrival signal holding means, and a reset signal generating means for resetting the first-arrival signal holding means. Fault point detection device for overhead distribution lines. 2. The first-arrival signal holding means has a pair of R-S flip-flop circuits, a pair of NAND circuits each receiving the output signal of the flip-flop circuit, and outputting the output signal of each of the pair of NAND circuits to the other one. 2. A fault point detection device for an overhead power distribution line according to claim 1, wherein the fault point detection device is an input. 3. The first-arrival signal holding means has a pair of D-type flip-flop circuits, and the inverted output signal of each of the flip-flop circuits is input to the other input terminal D. A fault point detection device for an overhead power distribution line according to any one of paragraphs 1 to 2.