JP2581584B2 - Power line carrier signal transmission device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power line carrier signal transmission device using an arc-extinguishing reactor grounded distribution line, and is particularly suitable for cooperating with an arc-extinguishing reactor control device. Power line carrier signal wire device.

[Conventional technology]

For the conventional power line carrier signal transmission equipment, see the Hitachi Hitachi Review Vol.65, No.6 (1983-6) Miyahara, Ikeda et al. It is stated in. However, the reference is directed to a high-resistance grounded distribution line, and no consideration is given to an arc-extinguishing reactor grounded distribution line. Regarding resistive grounding and arc-extinguishing reactor grounding, refer to the Electricity Calculation Vol. 43, 1975, Maruta, “Accidents in Distribution Substations and Concepts of Protection and Relay Systems,” 3. Accident Phenomena, (1) Ground Fault The purpose and operation of the accident are described in the accident section. However, this document aims at system protection and does not consider power line transportation.

[Problems to be solved by the invention]

The above prior art does not consider the distribution line of the arc-extinguishing reactor grounding. In particular, since the arc-extinguishing reactor control device selectively controls the impedance of the arc-extinguishing reactor while measuring the zero-phase voltage, the following description will be given. There was a problem.

First, the operation principle of the arc extinguishing reactor control device will be described.

In a distribution line, a slight zero-sequence voltage is usually generated due to unbalance of a load and unbalance of each phase of a ground capacitance. If this is defined as the residual zero-sequence voltage of the system and the generation of this residual zero-sequence voltage is determined as a micro-ground fault between one line and the ground, the equivalent circuit can be expressed as shown in FIG.
Vol.43, 1975, Fujihira, "How a ground fault directional relay works from the perspective of input and output," 4. Explanation of a ground fault.

_Rg is the impedance at a minute point in the line, 3C is the system-to-ground capacitance, L is the arc-extinguishing reactor, γ is the resistance of the arc-extinguishing reactor, and R is the parallel resistance. In such an equivalent circuit, the residual zero-sequence voltage V ₀ can be expressed by the following equation.

However, And

In the above equation, since γ is usually several% as compared with jωL, ignoring γ, Z ₀ becomes , That is, when the earth capacitance of the system is equal to the impedance of the arc-extinguishing reactor, the maximum value is obtained. The condition under which the zero-sequence voltage V ₀ becomes maximum is also when Z ₀ becomes maximum according to the equation (1).

The impedance of the arc-extinguishing reactor must be equal to the ground capacitance for the purpose of installation. From this, an arc-extinguishing reactor control device that switches the impedance of the arc-extinguishing reactor, measures the value of the zero-sequence voltage, obtains the impedance of the arc-extinguishing reactor that maximizes the voltage, and controls it is considered. It was implemented with such a configuration. The zero-phase voltage of the system is detected by a measuring instrument ground transformer (GPT) 11 connected to the substation bus 1, and the zero-phase voltage measurement circuit 22 converts an AC amount into a DC amount voltage, thereby controlling the arc extinguishing reactor. It is taken into the device (PC control device) 15. The arc-extinguishing reactor 18 is connected to an open delta open end of a grounding transformer (GTR) 16 connected to the substation bus 1 together with a parallel resistor 17. The tap changeover switch 19 is connected so that the impedance of the arc extinguishing reactor 18 can be changed, and the PC control device 15 controls on / off of the switch.

In the above configuration, the PC control device 15 switches the tap switching switch 19 at regular time intervals to select a tap at which the zero-phase voltage becomes maximum. For example, there are switching taps 1 to 21 and the arc extinguishing reactor 18 together with the number of taps.
Assuming that the impedance of the PC increases,
In the step 15, if the tap at the start of the switching operation is 10, the tap is switched to the next tap 11, the value of the zero-phase voltage is measured and compared with the zero-phase voltage at the time of the tap 10. The operation will be described below with the zero-phase voltage at each tap set to V10, V11,.

(A) When V10 <V11, the tap is further increased and V1
1 is compared with V12, and if V11> V12, the tap is switched to 11, and the PC control device 15 ends the switching operation. V11
In the case of <V12, the tap is further increased and the tap is switched to the tap at which the zero-phase voltage becomes the maximum.

(B) If V10> V11, switch the tap to 9, and
Is compared with V9, and if V10> V9, the tap is switched to 10, and the PC control device 15 ends the switching operation. V10 <V
In the case of 9, the tap is reduced and the tap is switched to the tap having the maximum zero-phase voltage.

The tap switching operation of the PC control device 15 when the power line carrier signal transmission device according to the related art is installed in the distribution substation where the PC control device 15 described above is installed and signals are transmitted and received will be described.

Now, it is assumed that the tap is set to 10, and the system-to-ground capacitance and the impedance of the arc-extinguishing reactor match each other.
Since the PC control device 15 performs the tap switching operation at regular time intervals, it is assumed that the tap control is switched from the tap 10 to the tap 11 and the zero-phase voltage is measured. If no zero-phase voltage is generated from the power line carrier signal transmission device, V10 should be larger than V11. However, at this time, if the power line carrier signal transmission device is transmitting and receiving signals, V10 <V11. Therefore, the PC controller further taps and compares the voltages of V11 and V12. At this point, if the transmission / reception operation of the power line carrier signal transmission device has been completed, V11> V12, so the PC control device 15 switches to the tap 11, and the tap switching operation ends. This causes a problem that the PC control device 15 cannot perform a normal switching operation.

Although the problem at the time of tap switching operation of the PC control device 15 at a fixed time interval has been described, the PC control device 15 includes:
Furthermore, after detecting a sudden change in the zero-sequence voltage and detecting a sudden change,
It also has a function of performing a tap switching operation. This is for performing a tap switching operation promptly when the ground capacitance changes due to an accident in the system or a system switching operation. However,
When the residual zero-sequence voltage becomes small, the zero-sequence voltage generated by the power line carrier signal transmission device cannot be ignored, and the change of the zero-sequence voltage in the signal transmission / reception operation is performed by the PC controller
The problem 15 is that a sudden change is detected and a tap switching operation is performed.

An object of the present invention is to allow the PC control device 15 to perform a regular tap switching operation and detect only a sudden change in the regular zero-phase voltage even when the power line carrier signal transmission device performs a signal transmission / reception operation. An object of the present invention is to provide a power line carrier signal transmission device capable of coordinating operations.

[Means for solving the problem]

The above-described problem is caused by a grounding transformer for an instrument connected to a substation bus, a zero-phase voltage measuring circuit that inputs and rectifies a zero-phase voltage of the bus from the grounding transformer for the instrument, and is connected to the bus. A grounding transformer, an arc-extinguishing reactor connected to the grounding transformer, and an arc-extinguishing reactor control device for controlling tap switching of the arc-extinguishing reactor in accordance with the output of the zero-phase voltage measuring circuit. An arc reactor device; a master-station zero-phase voltage generating circuit for grounding one phase of the bus via an impedance and changing the impedance value to generate a zero-phase voltage; and a zero-phase voltage of the bus connected to the bus. A master station zero-phase voltage generation circuit for detecting a voltage; a master station demodulation circuit for encoding a change in output of the master station zero-phase voltage generation circuit; an input of an encoded signal of the master station demodulation circuit; Zero-phase voltage generation in station zero-phase voltage generation circuit A master station transmission / reception main circuit; and a high-voltage distribution line connected to the bus, grounding one phase of the distribution line via an impedance, and changing the impedance value to generate a zero-phase voltage. A phase voltage generation circuit;
A slave station zero-phase voltage generation circuit connected to the distribution line to detect a zero-sequence voltage of the distribution line; a slave station demodulation circuit for encoding a change in output of the slave station zero-phase voltage generation circuit; A slave station transmission / reception main circuit that inputs a coded signal of the circuit and instructs the slave station zero-phase voltage generation circuit to generate a zero-sequence voltage;
In a power line carrier signal transmission device using a zero-phase carrier transmission method, wherein the distribution line and the bus are used as a signal transmission path between the master station transmission / reception main circuit and the slave station transmission / reception main circuit, Signal transmission period control for intermittently performing signal transmission between a master station transmission / reception main circuit and the slave station transmission / reception main circuit and outputting a transmission period signal for performing the signal transmission and a non-transmission period signal for not performing the signal transmission Circuit;
Subsequent to the zero-phase voltage measurement circuit, when the non-transmission period signal is input from the signal transmission period control circuit, the output of the zero-phase voltage measurement circuit is directly output to the arc extinguishing reactor control device, When the transmission period signal is input, the output of the zero-phase voltage measurement circuit is held, and the output of the zero-phase voltage measurement circuit immediately before the transmission period signal is input is output to the arc extinguishing reactor control device. The problem can be solved by providing a hold circuit.

[Action]

The sample-and-hold circuit includes a non-transmission period signal indicating a period during which the signal transmission period control circuit does not transmit a signal between the master station transmission and reception main circuit and the slave station transmission and reception main circuit and does not generate a zero-phase voltage at the substation bus. When a signal is transmitted between a master station and a slave station, the signal is input alternately with a transmission period signal indicating a period during which a zero-phase voltage is generated in the substation bus, and when the non-transmission period signal is input, the zero-phase voltage When the output of the measurement circuit is output to the arc extinguishing reactor control device as it is and the transmission period signal is input, the output of the zero-phase voltage measurement circuit is held and the non-transmission period immediately before the transmission period signal is input. Since the output of the zero-phase voltage measurement circuit based on the signal is output to the arc extinguishing reactor control device, the arc extinguishing reactor control device transforms the power by the signal transmission between the master station transmitting and receiving main circuit and the slave station transmitting and receiving main circuit. Mother It is possible to control the extinguishing reactor without being affected by the zero-phase voltage generated in. When a signal for controlling the operation of the arc-extinguishing reactor during the transmission period signal generation period is input to the zero-phase voltage measurement circuit, the signal is not immediately input to the arc-extinguishing reactor control device, but the transmission period The non-transmission period signal is input after the signal, and the switching period of these two signals is sufficiently shorter than the operation time of the arc extinguishing reactor. Therefore, the tap switching operation and the sudden change detecting operation of the arc extinguishing reactor are performed normally. Done.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The substation bus in the distribution substation is connected to the master station 4, which transmits and receives signals to and from the slave station 9, the instrument ground transformer (GPT) 11, which extracts the zero-phase voltage of the system, and the zero-phase circuit. Arc reactor
Ground transformer (GTR) 1 for connecting 18 and parallel resistor 17
6 is connected. The master station 4 extracts a zero-phase voltage generation circuit 6 for generating a zero-phase voltage in the system, and a zero-phase voltage signal and a reference phase voltage signal proportional to the zero-phase voltage of the system and the reference phase voltage from the substation bus 1. -Phase voltage dividing circuit 5 for inputting a zero-phase voltage signal and a reference phase voltage signal from the zero-phase voltage dividing circuit 5, and a zero-phase voltage generating circuit 6 installed in the slave station 9.
A demodulation circuit 7 for extracting a change in the zero-phase voltage of the system generated by the above and demodulating the transmitted ON-OFF signal;
The master station transmits a control command or a measurement command to the master station 4 via the zero-phase voltage generation circuit 6 and receives and processes the return information from the slave station 9 by receiving the demodulated output of the demodulation circuit 7. And a transmission / reception main circuit 8. Further, the master station transmission / reception main circuit 8 intermittently performs signal transmission between the master station transmission / reception main circuit and the slave station transmission / reception main circuit, and transmits a transmission period signal (sample command) for performing the signal transmission and the signal transmission. A signal period control circuit that outputs a non-transmission period signal (hold command) that is not performed is built in, and a sample / hold command 20 is output to the zero-phase voltage measurement circuit 14.

The slave station 9 receives a control command or a measurement command from the master station 4 and receives control and measurement commands from the zero-phase reception voltage divider 5, the zero-phase voltage generator 6, the demodulation circuit 7, and performs control and measurement processing. And a main transmitting / receiving main circuit 10 for replying, and is connected to the high voltage wiring 2 drawn from the substation bus 1.

Since the zero-phase voltage of the system is taken out from the open delta open end of the instrument grounding transformer 11, the zero-phase voltage measurement circuit 14 inputs this, and the rectifier circuit 12 converts the AC voltage into a DC voltage, and the sample-and-hold circuit. The output 21 is output to the arc extinguishing reactor control device 15 via the reference numeral 13. The operation of the zero-phase voltage measuring circuit 14 will be described with reference to FIG. FIG. 4 (a) shows a zero-phase voltage waveform of the system, and a dotted line shows a change in the magnitude of the voltage. In the figure, the time zone of t ₁ , t ₃ , t ₅ indicates the residual zero-phase voltage of the system, and the time zone of t ₂ , t ₄ indicates the time when the zero-phase voltage of the system changes by the zero-phase voltage generation circuit 6. Is shown. In response to such a change in the zero-sequence voltage, the output of the rectifier circuit 12 outputs a DC voltage V1 proportional to the residual zero-sequence voltage as shown in FIG.
And a DC voltage V2 when the zero-phase voltage is changed by the zero-phase voltage generation circuit 6. On the other hand, when the sample / hold command 20 is given to the sample / hold circuit 13 as shown in FIG. 4 (c), the output 21 becomes the residual zero-phase voltage as shown in FIG. 4 (d). Only the proportional DC voltage V1 is output. The master station transceiver main circuit 8, it is possible to manage the time the zero-phase voltage generator 6 of the master station side or daughter operates, as in the FIG. 4 (c), the t _2, t ₄ That is, the hold command can be output in synchronization with the time zone. Further, when changing the sample command from the hold command, t delayed by What time τ than the time period at the end of ₂ and t _4, the response time for the output to follow the input to the circuit 12 of the rectifier circuit 12 Is considered. In this manner, the zero-phase voltage measurement circuit 14 can output only the magnitude of the residual zero-phase voltage to the arc-extinguishing reactor control device 15.

Arc-extinguishing reactor 18 connected to grounding transformer (GTR) 16
Is provided with a tap so that the impedance can be changed, and a tap changeover switch 19 is connected.
This tap switching switch 19 is an arc extinguishing reactor control device.
The tap is switched by the arc extinguishing reactor 15 under the control of the control unit 15.

Next, the tap switching operation of the arc extinguishing reactor control device 15 will be described with reference to FIG.

The arc extinguishing reactor control device 15 performs tap switching operation at regular time intervals, and confirms whether the arc extinguishing reactor 18 correctly compensates for the earth capacitance 3 of the distribution line.
Assume that the tap switching operation is started at time T0 in FIG. 5 (d). Assuming tap 10 before T0,
At time T0, the tap is switched to 11. Fig. 5 (a)
Indicates the output of the rectifier circuit 12, where the residual zero-sequence voltage at tap 10 is V1, the voltage at tap 11 is V3, and the voltage at tap 9 is tap 9.
V5. The zero-phase voltages generated by the master station 4 or the slave station 9 are V2, V4, and V6. FIG. 5 (b) shows a sample / hold command 20, and FIG. 5 (c) shows an output 21. Even if the tap is switched to 11 at time T0, the output 21 still outputs V1, but at the time T1 when the arc extinguishing reactor controller 15 confirms the magnitude of the zero-phase voltage and switches to the next tap. Since the output 21 has also changed to V3, the arc-extinguishing reactor control device 15 can compare V1 with V3, and can make a correct determination. Therefore, if the tap 10 is a tap that correctly compensates for the ground capacitance 3, V1> V3, and the tap 9 is switched at time T1. Similarly, at time T2, since the output 21 has changed to V5, V1 and V5 can be compared, and a correct determination can be made. Since V1> V5, the tap is switched to 10 at time T2, and the tap switching operation is completed. During this time, even if the master station 4 and the slave station 9 perform transmission and reception, only the residual zero-sequence voltage is output at the output 21, so that the arc extinguishing reactor control device 15 has no effect on the operations of the master station 4 and the slave station 9. Instead, the tap switching operation can be performed. Although FIG. 5 shows an example in which the sample-and-hold command 20 shown in FIG. 5B is performed only once between the times T0 and T1, the arc-extinguishing reactor control device 15 performs tap switching. A confirmation time is provided until the residual zero-sequence voltage of the system changes and stabilizes. The confirmation time and the transmission time transmitted by the master station or the slave station at one time are always set so that (confirmation time)> (transmission time). Therefore, since the sampling command must be generated at least once during the time T1 after the time T0, the arc extinguishing reactor control device 15 correctly detects the change in the residual zero-phase voltage due to the tap switching in any communication state. You can judge.

Next, the operation of the arc quenching reactor controller 15 for detecting a sudden change in the zero-phase voltage will be described with reference to FIG. FIG. 6 (a)
Indicates a change in the DC output of the rectifier circuit 12, and V1 and V3 are DC outputs proportional to the magnitude of the residual zero-sequence voltage of the system.
2, V4 denotes a DC output proportional to the magnitude of the zero-phase voltage of the system changed by the master station 4 and the slave station 9. FIG. 6 (b)
Indicates a sample-and-hold command 20, and FIG.
The output 21 is shown. The output 21 outputs only the magnitudes V1 and V3 of the residual zero-sequence voltage according to the sample / hold command 20,
Since V2 and V4 are not output, the arc extinguishing reactor controller 15
Detects only that the zero-phase voltage has changed from V1 to V3 at time T, and does not detect the change due to the zero-phase voltage generated by the master station 4 and the slave station 9.

As described above, the arc-extinguishing reactor control device 15 can correctly detect the change in the residual zero-sequence voltage, and can perform the sudden change detection operation without being affected by the operations of the master station 4 and the slave station 9 at all.

According to the present embodiment, the arc extinguishing reactor control device 15 is not affected at all by the zero-phase voltage generated by the master station 4 and the slave station 9 even when the transmission / reception operation is performed by the master station 4 and the slave station 9. In addition, there is an effect that the tap switching operation and the sudden change detection of the zero-phase voltage can be performed.

Next, another embodiment in which the zero-phase voltage measuring circuit 14 is constituted by the rectifier circuit 12 as shown in FIG. 7 will be described. The rectifier circuit 12 shown in FIG. 7 receives an AC input proportional to the zero-phase voltage of the system obtained from the instrument grounding transformer (GPT) 11, performs full-wave rectification with a diode, and then operates an operational amplifier (op-amp) and a resistor. Low-pass filter circuits 23, 24,
According to 25 and 26, a DC voltage proportional to the magnitude of the AC input is extracted. The difference between the low-pass filter circuits 23 to 26 is that only the values of the resistor and the capacitor are different, and the circuit configuration is the same. With the circuit configuration as described above, the low-pass filter circuit having a high-speed response can be compared with the low-pass filter circuit 27 including a resistor and a capacitor as shown in FIG. 8 which is known as the simplest low-pass filter circuit. Can be configured. For example, the response of the rectifier circuit 12 to a change in the AC input can be evaluated by the output response characteristic of the low-pass filter to the step input shown in FIG. FIG. 9, A is shows the response to step input in the series connection of a seventh view of a low-pass filter circuit 23-26, the response time (t _A
−t ₀ ) is about 70 ms. 9 and B show the response to the step input of the low-pass filter circuit 27 of FIG. 8, and the response characteristic is expressed by the following equation.

Here, E _OB is an output voltage, and E _i is a step input voltage.

The time t _A was set so as not to affect the sudden change detection and the tap switching operation of the arc extinguishing reactor control device 15, and the output became 99% of the final value with respect to the step input. In contrast, the time t _B, if only to focus on the step inputs (E _i), it is possible to the same or less than the time t _A, the actual input is full-wave rectified waveform of the AC input Therefore, in order to extract only the DC voltage, the second harmonic must be attenuated. Therefore, it is necessary to consider the attenuation characteristic. In the case of a full-wave rectified waveform, the second harmonic is included at a rate of 66.7% of the DC component. Therefore, in order to attenuate the second harmonic component to 1% or less, it is necessary to set the time constant, that is, the value of R1 × C1 to 0.08845 seconds or more. For this reason, the value of R1 × C1 needs to be 0.08845 seconds or more, and the time t _B is necessarily 0.405 seconds or more according to the equation (2).

In the rectifier circuit 12 shown in FIG. 7, the values of the low-pass filter circuits 23 to 26 are determined so that the second harmonic is attenuated to 1% or less. Is about 70 ms.

As described above, in the rectifier circuit composed of the primary low-pass filter including the resistor and the capacitor as shown in FIG. 8, it takes 0.4 seconds or more to follow the change in the zero-phase voltage of the system. Therefore, the non-communication time from when the master station 4 transmits to when the slave station 9 starts to reply next needs to be 0.4 seconds or more. In the 60 Hz system, when one bit / cycle is used, one word is 0.133 seconds, so that the non-communication time is equivalent to the communication time of three words, and is a time that cannot be ignored. On the other hand, by using a high-order low-pass filter circuit according to the present invention, the ripple of the DC voltage output can be reduced to 1% or less, the response time can be reduced to about 70 ms, and the non-communication time can be reduced to 83 ms (5 cycles). ). In a power line carrier signal transmission device based on the zero-phase carrier transmission method, an idle time of several cycles is usually provided between a master station transmission and a slave station reply to distinguish between transmitted and received words. It doesn't matter. That is, according to the present embodiment, there is an effect that, even from the power line carrier signal transmission device side, the control and monitoring of the slave station can be performed without being affected by the transmission / reception operation by the presence or absence of the arc extinguishing reactor control device. .

〔The invention's effect〕

According to the present invention, even when a power line carrier signal transmission device is installed in a distribution substation in which an arc extinguishing reactor control device is installed, the power line carrier signal transmission device intermittently performs transmission and reception, and performs transmission and reception. There is a remarkable effect that the arc-extinguishing reactor can be controlled without impairing its function by utilizing the zero-phase voltage of the power distribution system during a period of no time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram expressing the generation of a residual zero-sequence voltage as a micro-ground fault between one line and the ground, and FIG. 3 shows a conventional example. Block diagram, fourth
The figure is a waveform diagram for explaining the operation of the zero-phase voltage measurement circuit,
FIGS. 6 and 7 are waveform diagrams for explaining the operation of the arc extinguishing reactor control device. FIG. 7 is a circuit diagram of another embodiment.
FIG. 9 is a circuit diagram of a low-pass filter including a resistor and a capacitor. FIG. 9 is a response characteristic diagram of the low-pass filter to a step input. 1 ... Substation bus, 2 ... High-voltage distribution line, 3 ... Capacitance to ground, 4 ... Master station, 5 ... Zero-phase voltage dividing circuit, 6 ... Zero-phase voltage generating circuit, 7 ... Demodulation circuit, 8 master station transmission / reception main circuit, 9 slave station, 10 slave station transmission / reception main circuit, 11 instrument ground transformer, 12 rectifier circuit, 13 sample / hold circuit, 14… Zero phase voltage measurement circuit, 15… Arc extinguishing reactor controller, 16… Grounding transformer, 17… Parallel resistor, 18… Arc extinguishing reactor, 19… Tap switching switch, 20… Sample・ Hold command, 21 …… Output, 22…
… Zero-phase voltage measurement circuit, 23,24,25,26 …… Low-pass filter circuit, 27 …… Low-pass filter circuit.

Continuing from the front page (72) Eisaburo Sakami 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Kokubu Plant, Hitachi, Ltd. (72) Kazuo Nishijima 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Hitachi Kokubu Plant (72) Inventor Yoshiki Soda 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Inside Shikoku Electric Power Company (72) Inventor Shuji Sakairi 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Inside Shikoku Electric Power Company (56) References JP-A-57-189518 (JP, A) JP-A-57-193936 (JP, A)

Claims (2)

(57) [Claims] 1. A grounding transformer for an instrument connected to a substation bus, a zero-phase voltage measurement circuit for inputting and rectifying a zero-phase voltage of the bus from the grounding transformer for the instrument, and a zero-phase voltage measuring circuit connected to the bus. A grounding transformer, an arc-extinguishing reactor connected to the grounding transformer, and an arc-extinguishing reactor control device for controlling tap switching of the arc-extinguishing reactor in accordance with the output of the zero-phase voltage measuring circuit. An arc extinguishing reactor device;
A master station zero-phase voltage generating circuit for grounding the phase via impedance and changing the impedance value to generate a zero-phase voltage, and a master station zero-phase voltage connected to the bus and detecting the zero-phase voltage of the bus A generation circuit, a master station demodulation circuit for encoding a change in output of the master station zero-phase voltage generation circuit, an input of an encoded signal of the master station demodulation circuit, and a zero-phase signal for the master station zero-phase voltage generation circuit. A master station transmission / reception main circuit for instructing voltage generation; and grounding one phase of the distribution line via an impedance to a high-voltage distribution line connected to the bus, generating a zero-phase voltage by changing the impedance value. A slave station zero-phase voltage generation circuit, a slave station zero-phase voltage generation circuit connected to the distribution line and detecting a zero-sequence voltage of the distribution line, and a change in output of the slave station zero-phase voltage generation circuit. A slave station demodulation circuit, and an input of an encoded signal of the slave station demodulation circuit; A slave station transmission / reception main circuit for instructing generation of a zero-phase voltage in the slave station zero-phase voltage generation circuit; and connecting the distribution line and the bus between the master station transmission / reception main circuit and the slave station transmission / reception main circuit. In a power line carrier signal transmission device using a zero-phase carrier transmission system as a signal transmission line, the master station transmission / reception main circuit intermittently performs signal transmission between the master station transmission / reception main circuit and the slave station transmission / reception main circuit. A signal transmission period control circuit for outputting a transmission period signal for performing the signal transmission and a non-transmission period signal for not performing the signal transmission; following the zero-phase voltage measurement circuit, the signal transmission period control circuit When the non-transmission period signal is input, the output of the zero-phase voltage measurement circuit is directly output to the arc extinguishing reactor control device, and when the transmission period signal is input, the output of the zero-phase voltage measurement circuit is held. , Just before entering the period signal transmission, the power line carrier signal transmission device is characterized in that a sample-and-hold circuit for the output of the zero-phase voltage measurement circuit and outputs the extinguishing reactor control. 2. A zero-phase voltage measuring circuit comprising: a full-wave rectifier circuit comprising a diode; and a low-pass filter using a voltage follower comprising an operational amplifier, a resistor and a capacitor following the full-wave rectifier circuit. A circuit connected in multiple stages in series,
An apparatus according to claim 1, wherein the apparatus comprises: