JPH0248867B2 - KAKUHAIDENSENNOJIKOTENTANSAHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the fault point when a ground fault occurs in an overhead high-voltage distribution line for some reason, resulting in a power outage.

The following method was considered as an example of a method for searching for this type of accident point. That is, a carrier signal of about 100Hz to 1000Hz is placed on an overhead high-voltage distribution line that has experienced a power outage due to a ground fault, and an explorer moves along the overhead high-voltage distribution line with a receiver for the carrier signal. If the carrier signal passes through the accident point during the movement process, most of the carrier signal disappears, so a method was devised to detect the disappearance on the display section of the receiver to determine the accident point.

However, with this method, if the road is in the state shown in Figures 1 or 2, the level entering the receiver will change (become lower) when passing the point shown by B. Although the actual accident point is the location indicated by A, there is a problem in that point B is mistakenly designated as the accident point.

Therefore, in order to solve the above-mentioned problems, the present invention makes it possible to easily search for the fault point, and in addition, in the case where the fault point may be approached or separated from the distribution line as shown in FIG. 1 or 2 during the search process. but,
The object of the present invention is to provide a fault point detection method for overhead power distribution lines that can accurately detect fault points regardless of such circumstances.

In order to achieve the above object, the present invention carries an exploration signal to the overhead power distribution line involved in the accident, and the exploration signal is such that the modulated wave signal is intermittent in one cycle of the carrier wave signal and the carrier wave signal. In a fault detection method for an overhead power distribution line using a signal superimposed on A signal and a modulated wave signal are received, and the amount of the positive polarity side and the amount of the negative polarity side of the received carrier wave signal are compared within the time when the received modulated wave signal exists, and the difference between them is calculated. The display is made to respond to the amount, and in the process of movement, the point of change in the display that appears on the display as the amount of the difference changes is found, and that point of change is searched as an accident point. The present invention provides a method for detecting fault points in overhead power distribution lines.

The drawings showing the embodiments of the present application will be described below. Figure 1 shows the situation where the fault point is being investigated, where 1 is a utility pole and 2 is an overhead voltage distribution line.
Shows the distribution lines involved in ground faults. Note that A indicates the accident point. 3 is a transmitter in the search device, one of its output ends is connected to the above-mentioned power distribution line, and the other end is grounded. 4 is an explorer, 5 is a receiver in the exploration device, and 6 is a road.

Next, in FIG. 3, which shows the circuit configuration of the transmitter 3 as a block diagram, 10 is a carrier wave oscillation circuit, which is configured to transmit a carrier wave signal. As shown in the figure, this carrier wave signal uses a 510 Hz sine wave intermittent at 3.3 Hz. 11
12 is a synchronous circuit, 12 is a gate circuit, and 13 is a modulated wave oscillation circuit, which is controlled by the synchronous circuit 11 and gate circuit 12, and is superimposed on the carrier wave signal so that the modulated wave signal is intermittent during one cycle of the carrier wave signal. Ru. That is, the modulated wave signal is configured to be superimposed on a portion of one cycle of the carrier wave signal. As an example, a 10.2 KHz signal is used as this modulated wave signal, and is output in synchronization with the peak portion of the carrier wave signal. 14 is an amplifier circuit which superimposes a modulated wave signal on the carrier wave signal and amplifies it to a required level (for example, 80 W). Reference numeral 15 denotes an output transformer, which is used to efficiently transfer the output signal of the amplifier circuit 14, that is, the exploration signal, to the distribution line 2.

Next, FIG. 4, which shows the circuit configuration of the receiver 5 as a block diagram, will be explained. In this circuit, waveforms at each point I to I are shown in FIGS. 5 and 6.
20 is an antenna designed to receive a modulated wave signal, and has a form suitable for receiving the signal;
configuration is used. Reference numeral 21 denotes a modulated wave signal receiving circuit, which extracts a modulated wave signal from the signal received by the antenna 20, and is composed of a well-known matching circuit 22, attenuation circuit 23, and LC tuning amplifier circuit 24, respectively. Next, reference numeral 25 denotes an antenna, which is designed to receive a carrier wave signal, and has a shape and configuration suitable for receiving the signal. Reference numeral 26 denotes a carrier wave signal receiving circuit, which extracts a carrier wave signal from the signal received by the antenna 25, and is composed of a well-known matching circuit 27, an attenuation circuit 28, and an LC tuning amplifier circuit 29, respectively. Note that the LC tuned amplifier circuit 29 has a small Q value. Next, 30 is a phase comparison circuit, which is a circuit designed to determine whether or not the modulated wave signal and the carrier wave signal are in phase with each other.
In this circuit 30, 31 is a waveform conversion circuit;
2 is a gate circuit configured to allow the signal from the carrier signal receiving circuit 26 to pass only when the signal from the waveform conversion circuit 31 is present. Reference numeral 33 denotes an integrating circuit configured to integrate only the positive polarity side of the signal from the gate circuit 32. Reference numeral 34 denotes an integrating circuit configured to integrate only the negative polarity side of the signal from the gate circuit 32. 35 is an inverting circuit. 36 is a comparison circuit, and 37 is a filter circuit, which is configured to pass a signal having the same frequency as the intermittent frequency of the carrier signal in the transmitter (3.3 Hz in this example). Reference numeral 38 denotes a DC conversion circuit which, when receiving input from the filter circuit 37, converts it into DC and outputs it. Next, numeral 39 is a display, for example a meter is used, and the output of the conversion circuit 38 is displayed by the deflection of the pointer. Furthermore, this display 39
Instead of a meter, a meter that emits light or emits an audible sound may be used.

Next, a description will be given of the search for an accident point using the above-mentioned search device and the operation of the receiver in that case. A probe signal is transmitted from the transmitter 3 to the power distribution line 2 as shown in FIG. 1 or 2. The voltage of this probing signal is indicated by V in FIGS. 5 and 6, respectively. When the above exploration signal is applied to the distribution line 2, a current as shown by C' in Fig. 5 flows in the distribution line 2 in section C before the fault point A, and in the section D after the fault point A.
A current as shown by D' in FIG. 6 flows through the distribution line 2.

This point will be explained based on FIGS. 7 to 9. Figure 7 shows accident point A during accident point exploration.
Nearby electrical equivalent circuit diagram, Figure 8 A is a vector diagram in section C, B is a vector diagram in section D, Figure 9
The figure shows (a) the voltage waveform of the exploration signal (V in Figures 5 and 6)
(b) Current waveform in section C (C' in Figure 5), (c)
In order to make it easier to see the mutual relationship between the current waveforms (D' in FIG. 6) in section D, a part of each is enlarged and the horizontal axes (time axes) are aligned.

First, as a matter of course, the position of the modulated wave signal at the voltage V in the time axis direction and the position of the modulated wave signal at the current in the time axis direction coincide (see FIG. 9).

Next, the phase will be explained. As shown in Fig. 7, the distribution line 2 in section C before the accident point A includes:
The current iC ₁ flowing in the ground capacitance C ₁ in section C, the current iR flowing in the fault point resistance R at fault point A, and the current iC ₂ flowing in ground capacitance C ₂ in section D after fault point A. A total current iO flows. If this is expressed in a vector diagram, it will look like Figure 8 A, and the above current
Due to the presence of iC ₁ and iC ₂ , the phase of the current iO is shifted from the phase of the voltage V by ψ.

On the other hand, as shown in Fig. 7, the ground capacitance of the distribution line 2 in section D after the accident point A is
Only the current iC ₂ flowing through C ₂ flows. If this is expressed in a vector diagram, it will be as shown in Figure 8 (b), and the above current
The phase of iC ₂ is shifted by 90° from the phase of the voltage V mentioned above. This phase point is shown in Figure 9 as follows:
As is clear from the comparison between (b) and (c), the current iC ₂ in section D clearly has a phase shift with respect to the current iO in section C.

With the exploration signal placed on the power distribution line 2 as described above, the explorer 4 moves on the road 6 along the power distribution line 2 with the receiver 5 in hand. First, in section C, the receiver 5 receives the probe signal shown as C' in FIG. 5, and the waveforms at each point I to I in the receiver 5 become as shown in FIG. That is, the modulated wave signal and the carrier wave signal are received by the antennas 20 and 25 as shown in A and B, respectively. The position of the received modulated wave signal A in the time axis direction matches the position of the modulated wave signal in the current iO in the time axis direction. Further, the waveform of the received carrier wave signal B and the waveform of the current iO match in the time axis direction. The received modulated wave signal is converted by the waveform conversion circuit 31 into a rectangular wave as shown in FIG. Since the gate circuit 32 allows the carrier signal to pass only in the portion corresponding to the rectangular wave, its output signal is as shown in E. The positive polarity component of this signal is integrated by the integrating circuit 33, as shown by F. Further, the negative polarity component of the output signal of the gate circuit 32 is integrated by the integrating circuit 34. Since this negative polarity component is small, only a small output is generated from the inverting circuit 35 as shown in G.

Therefore, the output of the comparison circuit 36 becomes as shown by H. This signal passes through a filter circuit 37, is converted into direct current by a conversion circuit 38, and is displayed on the display 3.
Added to 9. Then, the display 39 causes the pointer to wave in response.

In this case, as shown in (a), even if a noise signal other than the probe signal is input and it has the same frequency as the modulation wave signal or carrier wave signal,
The signal is processed as shown and does not affect the display on the display 39.

Eventually, when the explorer 4 passes the accident point A and reaches section D, the receiver 5 receives the exploration signal indicated by D' in FIG. The result is as shown in Figure 6.

That is, the modulated wave signal and the carrier wave signal are received by the antennas 20 and 25 as shown in A and B, respectively. The position of the received modulated wave signal in the time axis direction shown in A coincides with the position of the modulated wave signal in the current iC ₂ in the time axis direction. The waveform of the received carrier signal and the current shown in FIG.
The waveform of iC ₂ matches in the time axis direction. 6th
The modulated wave signal in Figure A matches the modulated wave signal in Figure 5 A in the time axis direction, whereas the carrier wave signal waveform in Figure 6 B and the carrier wave signal waveform in Figure 5 B are shifted in the time axis direction. This is due to the large phase shift between iO and iC ₂ in FIG. 9. By passing the carrier wave signal as described above through the gate circuit 32, the gate circuit 3
In the output signal No. 2, as shown by E, the amount on the positive polarity side and the amount on the negative polarity side are approximately equal. This output is subjected to similar integration in integration circuits 33 and 34, respectively. As a result, the output of the comparator circuit 36 disappears as shown by H, and therefore the indicator 33 does not move the pointer.

In this case, even if the same noise as in the previous case is input as shown in (b), and the resulting signal appears at the output of the comparator circuit 36 as shown in (b)', the signal will not pass through the filter circuit. removed by 37,
The display on the display 39 is not affected.

Therefore, by finding a point where the display on the display 39 changes while looking at the display 39 while moving as described above, the explorer 4 can know that point as a ground fault point.

In this case, as described above, the amount of the positive polarity side and the amount of the negative polarity side of the received carrier wave signal are compared within the time period in which the received modulated wave signal exists, and the amount of the difference is calculated. Since the display 39 is designed to respond to the situation, as shown in FIG. 1, the road 6 is curved or there is a step 6a
Even if the distance between the power distribution line 2 and the receiver 5 changes due to excessive heat, even if the reception level of the exploration signal changes due to the change in distance, the display 39 will not give an incorrect display. do not have.

As described above, in the present invention, while transmitting an exploration signal to the distribution line 2 involved in the accident, the receiver 5 is moved along the distribution line 2 involved in the accident, and the exploration signal entering the receiver 5 is transmitted. Since the accident point is discovered by detecting changes in signals, the explorer 4 who investigates the accident simply moves along the road 6 along the distribution line 2 involved in the accident while holding the receiver 5. It has the advantage of being able to easily and accurately locate the accident point A.

Furthermore, in the present invention, in the process of moving along the road along the distribution line 2 with the receiver 5 as described above, the road 6 is curved as shown in FIG. As shown in the step 6a
Even if the level of the exploration signal received by the receiver 5 fluctuates due to fluctuations in the level of the exploration signal received by the receiver 5, the accident point is determined as described above, so the accident point can be determined without being confused by such fluctuations. It also has the advantage of being able to be detected accurately.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIGS. 1 and 2 are diagrams showing the investigation state of the accident point, FIG. 3 is a block circuit diagram of the transmitter, and FIG. 4 is a block circuit diagram of the receiver. , FIG. 5 and FIG. 6 are diagrams showing waveforms at each point on the power distribution line and in the receiver, FIG. 7 is an equivalent circuit diagram, FIG. 8 is a vector diagram, and FIG. 9 is a waveform diagram for comparative explanation. 2... Overhead distribution line, 3... Transmitter, 4... Explorer, 5
...Receiver, 20, 25...Antenna, 21...Modulated wave signal receiving circuit, 26...Carrier wave signal receiving circuit, 30
...Phase comparator circuit, 39...Display device.

Claims (1)

[Claims] 1. An exploration signal was placed on the overhead power distribution line involved in the accident, and the exploration signal used a carrier signal and a signal that was superimposed with a modulated wave signal intermittent within one cycle of the carrier signal. In the fault point detection method for an overhead power distribution line, a receiver is moved along the power distribution line involved in the accident, and in the process of moving the receiver, the carrier wave signal and the modulated wave signal are received from the power distribution line, and the receiver is moved along the power distribution line involved in the accident. Comparing the amount of the positive polarity side and the amount of the negative polarity side of the received carrier wave signal within the time period in which the received modulated wave signal exists, and causing a display device to respond to the amount of the difference, An accident on an overhead power distribution line characterized in that, in the process of said movement, by finding a change point in the display that appears on the display as the amount of difference changes, the change point is searched as a fault point. Point exploration method.