JPS6329456B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a signal transmission system using low-voltage distribution lines, and particularly to a signal transmission system using low-voltage distribution lines for transmitting various signals necessary for a comprehensive automation system for power distribution. The present invention relates to a preferred signal transmission system.

[Background of the Invention] Today, most of the power distribution systems using low-voltage distribution lines in Japan are the 100V/200V single-phase three-wire system shown in FIG. In other words, the primary side of the pole transformer 1 is connected to the 6600V high-voltage distribution line 2, and its secondary side is a three-wire system with two circuits of single-phase 100V; , the neutral wire of the pole transformer 1 is grounded to the earth by a grounding wire 3, and various 100V loads 5 and 200V loads 6 are connected to the low voltage distribution line 4 as shown in the figure. , the distribution system is
It is composed of many pole transformers 1 and low voltage distribution lines 4.

For such low-voltage distribution systems, it is possible to transmit signals between customers and consumers using low-voltage distribution lines for comprehensive automation of power distribution, such as load control of water heaters, etc., and automatic meter reading of electricity meters. desired.

There are two methods for transmitting signals using low-voltage distribution lines: a line-to-line circuit method and a ground return method.

The line-to-line circuit method transmits signals by superimposing them on two of the three single-phase wires, but the upstream signal from the customer end to the pole equipment is transmitted by a signal installed at each pole transformer. It is transmitted to the high voltage distribution line via the above-mentioned pole device. However, in this method, each pole transformer has an independent circuit, so it is necessary to install a pole device for each pole transformer.

On the other hand, since the earth return system has conventionally been a signal transmission system with the configuration shown in Figure 2, the pole transformer 1
It was necessary to install the pole-mounted device 7 in pairs.

That is, a pole-mounted device 7 has a voltage transformer 8 for transmission and a current transformer 9 for reception coupled to a grounding wire 3 that connects the neutral line on the secondary side of the pole-mounted transformer 1 to the earth.
On the customer end side, a receiving circuit 10 is installed between the neutral wire and the ground, and a switch is installed between one of the three low-voltage distribution lines 4 other than the neutral wire and the ground. 1
1 and an impedance 12, the terminal device 13 is installed therein.
In this way, from the pole device 7 to the terminal device 13
A down signal from the terminal device 13 to the pole device 7 is transmitted as shown by a solid arrow A, and an up signal from the terminal device 13 to the pole device 7 is transmitted as shown by a broken arrow B. By the way, in general,
The secondary neutral wire of the pole transformer 1 is connected to each pole transformer 1.
Since each pole transformer 1 is grounded, the above ground return method was applied to each pole transformer 1. However, this has the problem that as the number of pole-mounted transformers 1 increases, the number of pole-mounted devices 7 also increases, which is uneconomical.

[Purpose of the invention]

The present invention has been made in view of the above, and its purpose is to connect terminals connected to low-voltage distribution lines on the secondary side of a plurality of pole transformers by simply providing one pole-mounted device. The object of the present invention is to provide a signal transmission system using a low-voltage power distribution line that can communicate with all devices.

[Summary of the invention]

A feature of the present invention is that all the neutral wires of the low voltage side distribution lines of the plurality of pole transformers are connected, and the neutral wire of one of the plurality of pole transformers is connected. Install a pole-mounted device that connects a transmitter/receiver circuit only to the ground wire that connects the line to the earth, and block the earth return signal to each ground wire that connects the neutral wire of the other pole-mounted transformers to the earth. The point is that the structure has an inserted impedance.

[Embodiments of the invention]

The present invention will be explained in detail below using the embodiments shown in FIGS. 3 to 5.

FIG. 3 is a block diagram showing an embodiment of a signal transmission system using a low-voltage distribution line according to the present invention, and shows a case in which there are n pole transformers. In Figure 3, 1
a~1n are pole transformers, 2 are high voltage distribution lines, 3a~
3n is a grounding wire of the secondary side neutral line of the pole transformers 1a to 1n, 4a to 4n are low voltage distribution lines, and 6a to 6n are 200V loads connected to the low voltage distribution lines 4a to 4n.

By the way, in the present invention, the pole transformer 1a
The secondary neutral wires of ~1n are all connected with the overhead ground wire 14, and the ground wire 3 of the secondary neutral wire of the pole transformer 1a
A pole device 7 in which a voltage transformer 8 for transmission and a current transformer 9 for reception are combined is installed only on a, and the grounding wire 3b of the secondary side neutral wire of the other pole transformers 1b to 1n is installed. An impedance 15 for blocking the earth return signal was inserted in each of the impedances 1 to 3n.

FIG. 4 is a configuration diagram showing one embodiment of the impedance 15 in FIG. 3, which is a parallel circuit of an inductance 15a and a capacitor 15b, and has a value that satisfies the resonance condition at the signal frequency. Therefore, it has a high impedance for signals (high frequency), but has a low impedance for commercial frequencies and impulse surges, and fulfills the function of a grounding line.

On the other hand, on the consumer end side, terminal devices 13a to 13n each include a receiving circuit 10 connected between a neutral wire and the ground, and a transmitting circuit consisting of a switch 11 and a current power source 16 connected in parallel with the receiving circuit 10. The configuration was such that the following was installed.

In addition, in FIG. 3, the flow of downlink signals transmitted from the pole device 7 to all the terminal devices 13a to 13n is shown by solid arrows. The pole device 7 generates the same content as that transmitted via the high-voltage distribution line 2 as a signal at both ends of the grounding wire 3a (between the neutral wire and the earth) using the voltage transformer 8 for transmission. . This signal is transmitted to the overhead ground wire 14 and the low voltage distribution lines 4a to
Each terminal device 13a to 13n passes through the neutral wire of 4n.
The signal is received by the receiving circuit 10 and returns to the grounding point of the grounding wire 3a via the ground. At this time, ground wire 3
Since impedance 15, which has a large value with respect to the signal frequency, is inserted from b to 3n,
The signal current is not shunted to these.

FIG. 5 is the same configuration diagram as FIG. 3, and in FIG. 5, as an example, the flow of an upstream signal from the terminal device 13b to the pole device 7 is shown by a broken line arrow. Now, assuming that the terminal device to which a reply is to be sent is the terminal device 13b, by turning the current power supply 16 on and off with the switch 11, both ends of the terminal device 13b,
That is, a signal is generated between the neutral wire and the ground. This current signal passes through the neutral wire of the low-voltage distribution line 4b and the overhead ground wire 14, passes through the ground wire 3a to which the receiving current transformer 9 of the pole-mounted device 7 is connected, and circulates through the ground. . At this time as well, the grounding wires 3b to 3
Since the impedance 15 is inserted in n, the signal current will not be shunted.

With the above, signal transmission can be performed both up and down.

〔Effect of the invention〕

As explained above, according to the present invention, just by providing one pole-mounted device, it is possible to communicate with all the terminal devices connected to the low-voltage distribution line on the secondary side of a plurality of pole-mounted transformers. This has the advantage that other pole-mounted devices can be omitted.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a 100V/200V single-phase three-wire power distribution system, Figure 2 is a configuration diagram of a conventional ground return type signal transmission system, and Figure 3 is a signal transmission using the low-voltage distribution line of the present invention. FIG. 4 is a block diagram showing an embodiment of the system; FIG. 4 is a block diagram showing an embodiment of the impedance shown in FIG. 3; and FIG. 5 is a diagram for explaining the upstream signal in FIG. 3. 1a to 1n...Pole transformer, 2...High voltage distribution line, 3a to 3n...Grounding wire, 4a to 4n...Low voltage distribution line, 7...Pole device, 8...Voltage transformer for transmission , 9... Current transformer for reception, 10... Receiving circuit, 11... Switch, 13a to 13n... Terminal device, 14... Overhead ground wire, 15... Impedance, 16... Current power source.

Claims (1)

[Scope of Claims] 1. A pole-mounted device in which a transmitting/receiving circuit is coupled to a grounding wire connecting a neutral line of a low-voltage side distribution line of a pole-mounted transformer to the earth, and a pole-mounted device connected to the low-voltage side distribution line. In a ground return type signal transmission system consisting of one of the low-voltage side distribution lines installed near the load for load control and measurement and a terminal device having a transmitting and receiving circuit coupled between the ground, a plurality of a grounding wire that connects all the neutral wires of the low-voltage side distribution lines of the pole transformers and connects the neutral wire of one of the plurality of pole transformers to the ground; The pole-mounted device is installed only in the pole-mounted transformer, and each of the grounding wires connecting the neutral wire of the other pole-mounted transformers and the earth has an impedance inserted therein to block a ground return signal. A signal transmission system using low-voltage distribution lines. 2. The impedance is comprised of a parallel circuit of an inductance and a capacitor.
A signal transmission system using the low-voltage distribution line described in Section 1.