JPS634148B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a receiving device used for detecting a fault point on an overhead power distribution line using a high voltage pulse application method.

When a grounding fault occurs on an overhead power distribution line, the point of fault is detected using a high-voltage pulse application method. This involves applying a high voltage pulse to a section of line that is in a power outage state, and detecting the pulse current flowing through the distribution line using a receiver equipped with an antenna to locate the point of a ground fault.

The principle of such exploration will be explained below. FIG. 1 is a diagram showing a state in which a grounding accident point is being searched.
In the figure, 1 is the high voltage pulse generator, 2 is the distribution line, 3 is the ground, 4 is the ground fault point, Rg is the ground fault resistance, Cg is the ground capacitance after the ground fault point,
5 is a search coil antenna close to the power distribution line;
6 is a receiving device, and 7 is a lead wire connecting the antenna 5 and the receiving device 6.

In such a configuration, a high voltage pulse generator 1 applies a high voltage pulse between the power distribution line 2 and the ground 3, and a receiving device 6 equipped with an antenna 5 detects the current flowing through the power distribution line 2, thereby preventing a grounding accident. Explore points. In other words, Figure 2 shows the waveform of the voltage pulse generated by the high voltage pulse generator 1, and if the current flowing through the line due to the application of this high voltage pulse is integrated once, (a) If there is no grounding fault on the line, (b) There is an accident, and in the section from pulse generator 1 to the accident, the integral value becomes zero, (c) There is an accident, and the integral value is the fault current value. In the section after the accident, the integral value becomes zero, so by reading the integral value after a certain period of time, the above three types of values are discriminated and the accident point is searched.

However, in the case of a search coil type antenna, the antenna output is equivalent to passing the line current waveform through a kind of differentiation circuit once, so by performing the integration twice, the same result as above can be obtained.
Figure 3 shows an example of a conventional receiving device for accident point detection.
8 is an amplifier, 9 is a gate, 10 is a first integrator, 1
1 is a second integrator, 12 is a detection display gate, 13 is a detection meter, and 14 is a gate signal generator.

To explain the operating waveforms of the receiving device 6, FIG. 4 shows that when there is no accident on the track,
The figure shows the section from the high voltage pulse generator 1 to the fault when there is an accident on the line, and Figure 6 shows the case after the fault point, where a is the line current, b is the antenna output, and g ₁ is the gate signal generation. c is the output of the first integrator 10, d is the output of the second integrator 11, _g0 is the signal to the detection display gate 12 of the gate signal generator 14, e is the detection meter It is a swing of 13.

Next, the operation of the receiving device 6 will be explained. The output signal from the antenna 5 is amplified to a sufficient magnitude by an amplifier 8, and the gate signal generator 14 detects the first point in time of this signal and opens the gate 9 for a time longer than the pulse width of the high voltage pulse. , second integrator 1
Integrate twice using 0 and 11. Next, after a certain period of time, the detection display gate 12 is opened, and the detection meter 13 determines the state of the accident.

By the way, in a high resistance fault of several kilohms or more, the integrated value of the distribution line current becomes very small, so
Detecting high resistance faults was difficult because the effects of amplifier temperature drift and commercial frequency current flowing nearby could no longer be ignored.

Therefore, in order to search for high-resistance faults with conventional receiving devices, it has been necessary to calibrate the receiving device before the search. Furthermore, in areas where large commercial frequency currents are flowing (sections with large stray currents flowing through public ground lines or sections with double overhead wires), there is a drawback that erroneous detections may occur and a large amount of time is required for the search.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional system, and it provides a receiving device with an amplifier temperature compensation function and a function to remove malfunctions due to commercial frequency current, thereby eliminating the need for calibration operations and further reducing the need for commercial frequency current. The object of the present invention is to provide a receiving device that can extremely effectively detect high resistance faults even in sections where the wind is flowing.

An embodiment of the present invention will be described below.
FIG. 7 is a block diagram showing an embodiment of a receiving device for detecting a fault point in a distribution line according to the present invention, in which 8 is an amplifier;
is the first gate, 15 is the second gate, 16 is the subtracter, 10 is the first integrator, 11 is the second integrator, 12
13 is a detection display gate, 13 is a detection meter, and 14 is a gate signal generator, all of which are indicated by 17.

Next, the operation of this receiving device 17 will be explained. The output signal from antenna 5 is amplified to a sufficient magnitude by amplifier 8, and the first instant of this signal is detected by gate signal generator 14 to generate a series of gate open signals. First, the first gate 9 is opened for a time that is an integral multiple of one cycle of the commercial frequency and longer than the pulse width of the high voltage pulse from the time of reception, and the output of the amplifier 8 is allowed to pass. Next, a subtractor 16 with a subtraction function of (first gate output) - (second gate output)
The first integrator 10 and the second integrator 11 perform integration twice. Next, from the time when the first gate 9 is closed, the integration is stopped for one period of the commercial frequency or for a period much shorter than one period, for example, about 10 μs, and the integration contents of the first integrator 10 are returned to the initial state. Next, the second gate 15 is opened for the same time as the first gate, and the output of the amplifier 8 is polarized by the subtracter 16 (first gate 9
is closed), and the integration is performed twice in the same way as when the first gate 9 is open. Next, the detection display gate 12 is opened for a time shorter than the high voltage pulse application period, and the content of the second integrator 11 is indicated to the detection meter 13. Figure 8 shows the above operating waveforms, where a is the line current and b
is the output of the amplifier 8, _g1 is the first gate open period, c is the output of the first integrator 10, d is the output of the second integrator 11, _g3 is the integration pause period and the initial setting of the first integrator 10. (reset) signal, g ₂ is the second gate open section,
g ₀ is the detection display gate open section, e is the detection meter 13
This is the fluctuation.

Next, Section 9 describes the removal operation when the amplifier 8 has a DC component in its output due to temperature drift, etc.
This will be explained using the operation waveforms shown in the figure. Note that this figure does not include line current. Figure 9b shows the amplifier 8
This is the output DC voltage Ed when there is no input signal.
g ₁ indicates the open section of the first gate 9, and the output waveforms of the first and second integrators 10 and 11 at this time are waveforms as shown in c and d. _g3 is an integration pause interval and an initial setting of the first integrator 10, whereby the integration contents of the first integrator 10 are returned to the initial state. g ₂ indicates the open section of the second gate 15, and the first integrator 10
is integrated with opposite polarity by the subtracter 16, and the output of the second integrator 11 becomes zero. From this, amplifier 8
As long as it operates stably only in the section from the first gate 9 open to the second gate 15 closed, it will not affect exploration performance, and is extremely effective against long-period drifts such as temperature characteristics. .

Next, the removal operation when the antenna 5 receives induction of a commercial frequency current will be explained using the operating waveforms shown in FIG. Note that, like FIG. 9, this figure also does not include the line current. FIG. 10b shows the induced waveform of the commercial frequency current appearing at the output of the amplifier 8. Since the open interval g ₁ of the first gate 9 is an integral multiple of the period of the commercial frequency, the outputs of the first and second integrators 10 and 11 have different phases as shown in c and d, but the first gate 9 closes. It becomes zero at this point. g ₃ is an integration pause interval, at which time the first integrator 10 is returned to its initial state, but since the integral value is zero, it does not change. 2nd gate 15
Since the open interval g ₂ of is also the same time as the open interval g ₁ of the first gate 9, even if the polarity is reversed by the subtracter 16, the integral value becomes zero at the time when the second gate 15 closes. Note that according to this principle, distortion waves including odd and even harmonics can be removed no matter what phase the integration starts from.

As described above, according to the present invention, the receiving device is equipped with an amplifier temperature drift compensation function and a function to eliminate malfunctions caused by commercial frequency current. This makes it possible to very effectively search for high resistance faults even in places that are easily affected by frequency currents.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the state in which a ground fault point is being searched, Figure 2 is a diagram showing the waveform of the high voltage pulse of the high voltage pulse generator of Figure 1, and Figure 3 is a diagram showing the state in which the ground fault point is being searched. Block diagram of the receiving device, Fig. 4, Fig. 5,
FIG. 6 is an operating waveform diagram showing the principle of exploration, FIG. 7 is a block diagram of the receiving device of the present invention, and FIGS.
10 are operational waveform diagrams showing the principle of the present invention. In the figure, 5 is an antenna, 17 is a receiving device, and 8
is an amplifier, 9 is a first gate, 15 is a second gate,
16 is a subtracter, 10 is a first integrator, 11 is a second integrator, 13 is a detection meter, and 14 is a gate signal generator. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a distribution line fault point detection receiver equipped with an antenna that detects pulse current flowing through the distribution line by high voltage pulses repeatedly applied to the distribution line in order to detect fault points on the distribution line, first and second gates arranged in parallel to pass the received signal;
A subtracter for subtracting the received signal of the antenna that has passed through the gate, an integrator having a reset function and a first integrator and a second integrator arranged in series, and an instruction for the integral value of the second integrator. An indicator to open the first gate for a period corresponding to an integral multiple of the commercial power frequency from the start of the signal received by the antenna and larger than the pulse width of the high voltage pulse, followed by one period of pause. and a gate signal generator for opening a second gate for the same time as the first gate.