JPH04337930A - Signal injecting method for power line carrier - Google Patents

Abstract

PURPOSE:To efficiently realize power line carrier at low cost by injecting a signal voltage to a secondary coil side by using a current transformer for gauge. CONSTITUTION:When the signal voltage is injected to the secondary coil side of current transformers 21 and 22 for gauge as general electric equipments, on a primary coil side, a voltage corresponding to the current transformers 21 and 22 is generated. When inserting signals between three-phase power distribution lines by using these current transformers 21 and 22, the current transformers 21 and 22 are inserted into two phases (R and S phases) and when the signal voltage is injected while connecting the secondary coil side to a reverse polarity, the signals can be injected to the primary side of the R and S phases. As a result, the double signals can be injected between the lines of the R and S phases. When injecting signals to three-phase power distribution lines as a zero phase voltage, the current transformers are inserted into all the three phases and when the signal voltages are injected while parallelly connecting the secondary side coil, the signals can be injected to the respective primary sides or R, S and T phases. Then, this voltage snows signal injection as the zero phase voltage.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injecting signals into power line carriers.

0002

2. Description of the Related Art When transmitting various control signals to sub-substations and terminal load equipment, a large amount of cost is required to install new control lines. Therefore, power line transportation is a method of superimposing signals on existing power distribution lines and using the wiring lines as signal lines as they are. A dedicated injection device is required to inject signals into power lines.

0003

The conventional signal injection method for power line transport requires a dedicated injection device, which poses a problem in that the cost required to implement the method is high.

[0004] An object of the present invention is to provide a signal injection method for power line transport that can efficiently inject signals by using a current transformer (CT), which is a general electric device. be.

[0005]

[Means for Solving the Problems] The present invention is a method for injecting a signal into a power distribution line by power line conveyance, which is characterized by using an instrument current transformer and injecting the signal into the secondary winding side of the current transformer. do.

[0006] The present invention also provides a method for injecting signals into a three-phase power distribution line by power line transport, in which a voltage transformer is inserted into two phases, and their secondary windings are connected with opposite polarity. , is characterized by injecting a signal to the secondary winding side.

Furthermore, the present invention provides a method for injecting a signal into a three-phase power distribution line by power line transmission, in which a voltage transformer is inserted in each of the three phases, and their secondary windings are connected in parallel. It is characterized by injecting a signal to the next winding side.

[0008]

EXAMPLE First, a current transformer (CT) used in the method of the present invention will be explained. As shown in FIG. 1, when a signal voltage is injected into the secondary winding side of a current transformer (CT) 10, a voltage corresponding to the current transformer is generated on the primary winding side. For example, if the CT ratio is 50/5 and the injection signal is 10V, a voltage of 1V can be injected to the primary side.

When inserting a signal between the lines of a three-phase power distribution line using such an instrument current transformer, as shown in FIG. S phase), connect the secondary winding side with the opposite polarity, and inject a signal voltage. This means that a signal can be injected into the primary side of each of the R and S phases, but the resulting signal is This means that twice as many signals can be injected between the R-phase and S-phase lines, resulting in more efficient signal injection.

[0010] In order to receive the signal, a transformer (TR) or a potential transformer (PT) that can detect the line voltage is used.

Furthermore, when injecting a signal as a zero-phase voltage into a three-phase power distribution line using a current transformer, insert CTs 31, 32, and 33 in all three phases as shown in FIG. When the secondary windings are connected in parallel and a signal voltage is injected, R, S
, a signal can be injected to the primary side of each of the T phases, and this voltage means that the signal can be injected as a zero-sequence voltage (voltage to ground).

[0012]The reception of the signal is as shown in FIG.
It will be received by the capacitors 41, 42, 43 inserted between the ground and the detection resistor 44, but as a result, the signal voltage of, for example, 1V injected into each phase will be received by the capacitor 41, 42, 43, and the detection resistor 44.
42 and 43, and the detection resistor 44 receives three times as much received signal as the injection for one phase, which also results in efficient signal supply.

Both the line-to-line and zero-phase injection methods described above involve voltage injection, but the impedance on the power supply side can be considered to be 0 (both between the lines and between the ground), and the power supply side is short-circuited and grounded for the signal voltage. Similarly, the signal voltage can only be injected to the load side.

[0014]

[Effects of the Invention] As explained above, according to the present invention, it is possible to efficiently inject signals into power line carriers by using an instrument current transformer, which is a general electric device.
This has the effect of realizing power line transport at low cost.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating an instrument current transformer used in the present invention.

FIG. 2 is a diagram illustrating a method of injecting signals between lines.

FIG. 3 is a diagram illustrating a method of injecting a signal as a zero-phase voltage.

FIG. 4 is a diagram showing a receiving side device.

[Explanation of symbols]

10, 21, 22, 31, 32, 33 Instrument current transformer 41, 42, 43 Capacitor 44 Detection resistor

Claims (3)

[Claims] 1. A method for injecting signals into a power distribution line using power line transport, the method comprising using an instrument current transformer and injecting the signal into the secondary winding side of the current transformer. 2. A method for injecting a signal into a three-phase power distribution line by power line conveyance, comprising: inserting a voltage transformer into two phases;
A signal injection method for power line transmission, characterized by connecting the secondary windings with opposite polarities and injecting a signal into the secondary windings. Claim 3: In a method of injecting a signal into a three-phase power distribution line by power line transmission, an instrument current transformer is inserted in each of the three phases, their secondary winding sides are connected in parallel, and the secondary winding A signal injection method for power line transport characterized by injecting a signal to the side.