JPH0556827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a transmission system, and particularly to a transmission system for locating faulty sections of power transmission lines.

[Prior art] Power transmission lines are indispensable equipment for today's power transmission operations, and accidents involving these equipment can have an extremely serious impact on modern society, which is rapidly becoming electrified, and in some cases can cause damage in all directions. Social functions can also be paralyzed.

For this reason, overhead ground wires are installed to protect power transmission lines from lightning strikes, etc., and extremely reliable insulated support methods are adopted to prevent flash faults. We have yet to completely eliminate accidents. Therefore, in the event that such an accident should occur on a power transmission line, the next best challenge is to quickly determine the location of the accident.

Conventionally, so-called fault locators such as pulse radar, surge reception, and impedance methods have been used to detect the location of an accident, and all of these methods determine the location of the accident by determining the line length from the measurement point to the accident point. It's becoming like that.

However, with the conventional fault locator described above, although there is no problem with power transmission lines without branches, when applied to power transmission lines with branches, reflections at each branch point are superimposed on the received signal, making it difficult to locate accurately. There was a problem with becoming.

For this purpose, the current flowing through the overhead ground wire installed on the power transmission line is detected at multiple points, and the phase difference or absolute value of this current is monitored through the optical fiber in the optical fiber composite overhead ground wire (OPGW) at substations, etc. Various methods have been studied and proposed for transmitting information to a device and locating the section where the accident occurred. In this case, it is better to concentrate the fault current information (absolute value and phase) flowing through the OPGW in one place, and to improve the response to various types of faults, rather than locating the fault area in a separate manner at the tower. This is advantageous in terms of location accuracy, but in order to do this, it is necessary to transmit the fault current information in the form of a waveform, that is, the instantaneous current value, to the monitoring device from time to time. There was a problem that I couldn't solve.

[Problems to be Solved by the Invention] As described above, in the method of transmitting fault current information in the form of a waveform to a monitoring device in order to concentrate the fault current information in one place, the amount of information becomes too large and cannot be transmitted at high speed. There was a problem that it had to be done.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transmission system for locating a fault section of a power transmission line, which solves the problems of the prior art described above and can significantly reduce the amount of transmitted information.

[Means for Solving the Problems] The gist of the present invention is to transmit transmission information for locating accident sections,
Rather than the current waveform itself, the system summarizes the absolute value and phase of the overhead ground wire current and sends it to the monitoring device.

That is, a plurality of transmission devices are connected in series along the overhead ground wire to which the fault current waveform flowing through the overhead ground wire detected by the current detection sensor is supplied, and each transmission device calculates the absolute value of the current from the fault current waveform. At the same time, the phase is determined by measuring the time difference between the timing signal generated by the most upstream transmission device that is synchronized with the fault current waveform and the fault current waveform, and the absolute current value and phase of each part of the overhead ground wire determined by each transmission device are calculated. In this system, the information is multiplexed and concentrated while being relayed to other transmission devices to a monitoring device installed at the most downstream position.

[Operation] The fault current flowing through the overhead ground wire at the time of an accident is detected by a current detection sensor and supplied to the transmission device as a fault current waveform. Each transmission device determines the current absolute value and phase based on this fault current waveform, and uses this as fault current data at the point where the current detection sensor is installed. Then, the fault current data from the upstream transmission device is sequentially relayed and output, and after the last fault current data is relayed and transmitted, the local station data is sent out and all the data is collected in the most downstream monitoring device.

[Example] Examples of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 2 is a configuration diagram of a power transmission line system to which the transmission method for locating power line fault sections of the present invention is applied, and an optical fiber composite ground wire (OPGW) 10 is installed on the power transmission line. A current detection sensor 30 is attached to the OPGW 10 near the steel tower 20, and a transmission device 40 connects three current detection sensors 30 attached near each steel tower 20 as a set from upstream to downstream of the power transmission line. It will be installed over time. This transmission device 40 is installed on a steel tower 20, and the optical signal from the current detection sensor 30 of the steel tower section where the transmission device 40 is installed is sent to the transmission device 40 through an optical fiber 11 as shown in FIG. Further, the optical signals from the current detection sensors 30 on the left and right tower sections are sent to the transmission device 40 through the optical fiber 12 in the OPGW 10. On the other hand, the transmission devices 40 are connected in series by the optical fiber 13 in the OPGW 10, and reach the central monitoring device 50 at the downstream end through the optical fiber 14.

Figure 3 shows a current detection sensor 30 and a transmission device 40.
FIG. 4 is an explanatory diagram of waveforms of each part. A feed-through current transformer (CT) 31 is installed in the OPGW10, which is set to be in the magnetic saturation region, and a resistor 3 is connected to the secondary winding of the CT31.
2. A light emitting diode (LED) 34 is connected via a diode 33. Therefore, LED3
The optical signal emitted from the LED 34 has a shape corresponding to the half-wave rectified waveform of the alternating current, but since the CT 31 is set to be in the magnetic saturation region, the light emission waveform of the LED 34 has the shape shown in FIG. 4b. The width T ₁ of the light emission waveform of the LED 34 changes depending on the magnitude (peak value) of the current flowing through the OPGW 10 (FIG. 4a). this
The LED light emission signal is received by the photoelectric converter 41 through the optical fiber 11 or 12, converted into a rectangular wave having a width T ₁ as shown in FIG. 4c, and output. Therefore, the pulse width T ₁ after conversion by the pulse counter 42a which obtains the clock pulse from the pulse generator 44 is
By measuring the current peak value, the current peak value can be determined. Also, a timing signal is output from the timing signal output port 45c of the multiplex transmission device 45 at every fixed time interval transmission period T ₃ (here, set equal to the AC power transmission current period) sent from the most upstream transmission device 45. timing signal (TM in Figure 4 d)
The current phase can also be determined by measuring the width of the output waveform (FIG. 4e) of the flip-flop circuit 43, which is the time T2 from ₁ to the output of the photoelectric converter, using the pulse counter 42b. These measurement data T ₁ and T ₂ are input to data input ports 45a and 45b of the multiplex transmission device 45. In addition, 45
d is a reset output port of the multiplex transmission device 45.

FIG. 5 is an explanatory diagram showing the transmission procedure of data sent and received by the multiplex transmission device 45. First, when the data D1 from upstream is received, the timing signal TM is output, and the phase information _T2 is output. In addition to being used for measurement, all received data is relayed to the central monitoring device 50 side. Next, immediately after relaying and transmitting the last received data Di-1, the local station data Di consisting of _T1 and _T2 is sent out. Although FIGS. 3, 4, and 5 are omitted to show the case where one current detection sensor 30 is used, in reality, the above processing is performed on information from three sensors, and the sending data Di includes three sets of T ₁ and T ₂ information.

Perform the above procedure for each transmission device 40,
Finally, the peak values and phases of all the currents flowing through the OPGW 10 detected by the sensor 30 are collected by the central monitoring device 50.

As described above, according to this embodiment, the peak value and phase of the current flowing through the OPGW are used as the data to be transmitted to the monitoring device, so it is possible to significantly reduce the amount of information to be transmitted. For example, if a conventional method is adopted in which instantaneous current values are transmitted moment by moment to a central monitoring device and the peak value and phase are evaluated at the central monitoring device, one cycle of the current is sent in temporal divisions. Assuming that the number of divisions is n, it is desirable that n be larger in order to reproduce the current waveform, but it is necessary that at least n≧10. Therefore, compared to the conventional method described above, in the transmission method of this embodiment, the peak value T ₁ and the phase T ₂ are
Even if the transmission speed is taken into account, it is possible to reduce the transmission speed to 2/n, or increase the number of sensors to n/2 if the transmission speed remains the same.

In addition, by using CT in the magnetic saturation region, it is possible to obtain a pulse width proportional to the current peak value, making it possible to easily and accurately obtain peak values without the need for a special peak value detection circuit. I can do it.

Furthermore, since each transmission device is connected in series to multiplex transmit data, it is possible to use a single transmission line.

In the above embodiment, the period of the timing signal sent from the most upstream transmission device is set to be equal to the AC power transmission current period, that is, the period of the commercial frequency AC, but it may be set to be equal to or greater than the period.

[Effects of the Invention] In summary, according to the present invention, the transmission information for locating the accident section is summarized not as the current waveform but as the absolute value and position of the overhead ground wire current, and is concentrated and multiplexed to the monitoring device. As a result, it is possible to significantly reduce the amount of transmitted information, and there is no need to increase the transmission speed, which is an excellent effect.

[Brief explanation of drawings]

Figure 1 is a transmission system diagram of a transmission system for locating faulty sections of power lines according to an embodiment of the present invention, Figure 2 is a configuration diagram of a power transmission line system to which the transmission system is applied, and Figure 3 is a current detection sensor and transmission system. FIG. 4 is a diagram showing the circuit configuration of the device, FIG. 4 is an explanatory diagram showing waveforms of each part thereof, and FIG. 5 is an explanatory diagram showing the transmission procedure. In the figure, 10 is an overhead ground wire, 13 and 14 are optical fibers, 30 is a current detection sensor, 31 is a through-type current transformer, 34 is a light emitting diode, 40 is a transmission device,
TM is a timing signal.

Claims (1)

[Scope of Claims] 1. A plurality of transmission devices are connected in series along the overhead ground wire to which the fault current waveform flowing through the overhead ground wire detected by the current detection sensor is supplied, and each transmission device is supplied with the fault current waveform flowing through the overhead ground wire. In addition to finding the absolute current value from A transmission method for locating a fault section of a power transmission line, which is characterized by transmitting multiplexed current absolute value and phase to a monitoring device installed at the most downstream position while relaying it to other transmission devices. 2 The current detection sensor is composed of a feed-through current transformer used in the magnetic saturation region and a light emitting diode connected between the secondary windings of the transformer, and the fault current waveform detected by this is 2. The transmission system according to claim 1, wherein the light emission waveform has a width corresponding to a peak value of the light emission waveform, and the absolute value of the current is determined by measuring the width of the light emission waveform. 3. The transmission system according to claim 1 or 2, wherein each transmission device is connected in series by an optical fiber or an optical fiber composite overhead ground wire. 4. The transmission method according to claim 1, 2, or 3, wherein the period of the timing signal generated from the most upstream transmission device is equal to or longer than the period of commercial frequency AC.