JP3315423B2 - Apparatus and method for receiving carrier signal applied to electric circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of applying a carrier wave to a circuit when transmitting or receiving a desired signal using the circuit and a method of receiving the applied carrier.

[0002]

2. Description of the Related Art As means for transmitting monitoring data output from an insulation monitoring device or the like installed in a power receiving room to a control room or the like where a person is resident, an electric line such as a power line is used. When the electric circuit used at this time is a single-phase three-wire system, a voltage obtained by modulating a carrier wave with data to be transmitted is applied to the electric circuit via a second-class ground wire connected to a ground-side electric circuit of the single-phase three-wire circuit. At the receiving point, the modulated carrier signal (hereinafter referred to as "carrier signal") present between the ground-side electric circuit and the third-class ground is detected and demodulated to receive data. A transport system called a return route system is employed. As an example of the conventional means, there is an invention disclosed in Japanese Patent Publication No. 2-18009 by the same applicant.

However, in the above-mentioned conventional method, when detecting a carrier signal at a receiving point, a third-class ground wire generally provided on a housing of a load device is often used.
At this time, if the ground terminal of the housing of the load device with large leakage current or the ground terminal of the noise elimination filter is connected,
Or if the ground potential fluctuates for some reason,
The potential of the third-type ground point fluctuates. For this reason, when a carrier signal is detected between the ground-side electric circuit and the third-class ground at the receiving point as in the related art, the fluctuation of the potential is added as a noise voltage.
N has significantly deteriorated, and it has often been difficult to correctly demodulate received data. In recent years, due to an increase in leakage current due to a noise removal filter accompanying the introduction of various OA devices or an increase in the amount of various noise currents flowing into the ground accompanying the spread of inverter devices, the above tendency has become even more remarkable and has become a major problem. .

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional data transmission method using an electric circuit or the like. It is an object of the present invention to provide a receiving method and a transmitting method in which / N reduction is prevented.

[0005]

In order to solve such a problem, the present invention directly detects a carrier signal voltage at a receiving point from a single-phase three-wire circuit without using a third-class ground having a large ground resistance. This is to detect a carrier signal. That is, the commercial frequency voltages of the two non-grounded circuits of the single-phase three-wire circuit are 180 ° out of phase with each other, while the carrier signal voltage applied to the circuit is in phase with the two non-grounded circuits and the grounded circuit. Is applied.

FIG. 4 shows this relationship. The low-voltage circuit of the power receiving transformer T is a single-phase three-wire system, and the ground circuit 3 is a ground line 1.
The are Class II ground (E ₂₎ through, the carrier signal voltage e ₀ is applied to the ground line 1. When because it is a single-phase three-wire path ungrounded side path 2 commercial voltage between the ground-side electrical path 3 and V _0, the commercial voltage between the ground-side electrical path 3 and the non-grounded path 4 is V ₀ becomes paths 2,4 The voltage between them is 2V ₀ .
On the other hand, the voltage between the ungrounded side electric circuit 2, the grounded side electric circuit 3, the non-grounded side electric circuit 4, and the ground is V ₀ + e ₀ , as shown in FIG.
e ₀ and −V ₀ + e ₀ .

Therefore, if the sum voltage between the non-ground side electric circuits 2 and 4 is detected, V ₀ + e ₀ + (− V ₀ + e ₀ ) = 2e
_It becomes ₀ , and the carrier signal voltage is detected.

As described above, according to the present invention, the carrier signal voltage superimposed on the non-ground-side electric circuit is positively used to detect the carrier signal voltage. It is intended to provide a receiving method that eliminates the influence of noise due to potential fluctuation.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. The low-voltage-side electric circuit 3 of the single-phase three-wire power receiving transformer T is grounded to the second kind (E ₂ ) by the ground line 1, and the modulators MOD are connected to the electric lines 2, 3, and 4 by the injection transformer OT coupled to the ground line 1. The resulting carrier signal voltage is applied to the output and the carrier signal is
It is modulated by the output of V. On the other hand, at the receiving point, the non-ground side electric lines 2 and 4 are applied to the (−) input terminal of the operational amplifier (differential amplifier) OP via the high resistances R ₁ and R ₂ , and the ground side electric line 3 is connected to the high resistance R ₃ . OP via OP
(+) Input terminal.

A feedback resistor R is connected to the output terminal of the (-) input terminal of the operational amplifier OP, and the output of the operational amplifier OP is applied to the demodulator DEM via the commercial frequency rejection filter F. Obtains received data.

[0011] The voltage injection transformer OT is induced in the ground line 1 by the output of a modulated modulator MOD in the output data of the monitoring device SV and e _0, between paths 2-3 and path 3
Assuming that the commercial voltage between −4 and V ₀ is V ₀ , the voltages of the electric circuits 2, 3, and 4 with respect to the ground are respectively V ₀ + e _0, e _{0, and} −V ₀ + e
It becomes ₀ .

If the impedance at the (+) and (-) input terminals of the operational amplifier OP is high and the gain is sufficiently large,
The output voltage e of the operational amplifier OP is expressed by the following equation. e = − (R / R ₁ ) (V ₀ + e ₀ ) − (R / R ₂ ) (− V ₀ + e ₀ ) + [1 + ｛(1 / R ₁ ) + (1 / R ₂ )｝ R] e ₀ (1) If, for example, R ₁ = R ₂ in this equation, then from equation (1), e = e ₀ ... (2), and a carrier signal is detected. On the other hand, R ₁ ≠ R ₂
Then, the commercial frequency component remains in the output of the operational amplifier OP. Also has been set to V ₀ both voltage ungrounded path 2,4 relative path 3, in general there are some differences. Power-frequency components in the output of this resistor R ₁ or by adjusting the R ₂ operational amplifier OP can cancel.

However, in practice, it is sufficient to add a filter F for suppressing the commercial frequency component remaining after the operational amplifier OP and demodulate its output with the demodulator DEM. Although the operational amplifier OP is used in the above embodiment, it is clear that sufficient attention must be paid to power supply to this amplifier, and it is necessary to take measures such as using a floating power supply.

FIG. 2 is a block diagram showing a modified embodiment of the present invention. In the figure, T ₀ is a detecting transformer, while 5 of the input terminals 5 and 6 via the high-resistance value R _1, R ₂ in both ungrounded path 2 and 4 of the path connected, the other input terminal 6 is connected also to the ground path 3 via a high resistance value R _3.

According to this configuration, the voltage between the electric circuits 2 and 4 is added to the primary input terminal 5 of the detection transformer T ₀ , and at the same time, the voltage of the electric circuit 3 is applied to the other input terminal 6.
The primary side of the results in the detectable transformer T ₀ will flow a current corresponding to the voltage difference between the terminals 5 and 6.

At this time, the commercial frequency components of the electric circuits 2 and 4 are
Cancel each other because it is opposite phases, only the carrier signal component flows through the secondary side of the detecting transformer T _0. Thus, although omitted from the drawing through a filter F to suppress the commercial wave residual component as shown in Figure 1 the output of the secondary-side terminals 7 and 8 of the transformer T _0, input to the demodulator DEM, the moiety The received data is obtained by demodulating with.

As shown in the above embodiment, the present invention provides a commercial power supply component by adding a carrier signal voltage superimposed in phase on a single-phase three-wire circuit by using the properties of a single-phase three-wire circuit and adding the voltages of two ungrounded circuits. The present invention is not limited to the above embodiment, and various modifications are possible based on the principle of the present invention.

In the above embodiment, the operational amplifier and the detecting transformer are directly connected to the electric circuit.
It is clear that if a step-down transformer is inserted between 3-4 and these detection circuits are added thereto, it is advantageous for ensuring safety.

In applying the carrier signal to the electric circuit, the injection transformer OT is connected to the ground line 1. However, the present invention is not limited to this. Obviously, it may be made to penetrate through. In general, a single-phase three-wire circuit is generally provided as a single-phase two-wire circuit from a ground-side circuit and one of the two non-ground circuits to a general load device. In this case,
In some cases, the electric circuits 2, 3, and 4 shown in the above embodiment cannot be used simultaneously. In this case, the present invention can be implemented as follows.

FIG. 3 is a block diagram showing another embodiment of the present invention. In this example, the ground-side electric circuits 3 and 2
Of the two non-ground side electric circuits 2 and 4, only one 4 is used as electric circuits 22 and 23 to constitute a single-phase two-wire electric circuit,
This is an example in which a load device is connected to the electric circuits 22 and 23. With this case connects a new electric paths 22 and 23 to the primary side terminals 13 and 14 of the single-phase three-wire transformer T _2, connected to a secondary-side neutral terminal 16 of the transformer T ₂ and ground side electric path 22 Connect with line 18. Thus transformer T ₂ of the secondary new ungrounded side toward the output terminals 15, 17 path 19, 21 and the ground-side electrical path 20 (trans T ₂
New single-phase three-wire electric circuit comprising the above-mentioned terminal 16 is connected. For example the transformer T ₂ 1: if 1 turns ratio, the voltage against the ground of the path 19, 20, 21, respectively,
_{(V 0/2) + e} 0, e 0, - a _{(V 0/2) + e} 0.

Therefore, the electric lines 19, 20, 21 in which the electric lines 2, 3, 4 of the embodiment shown in FIGS.
If a detection circuit is provided in place of the above, a carrier signal can be similarly received.

Therefore, the present invention can be applied to a single-phase two-wire system which is branched from a single-phase three-wire circuit by converting it to a single-phase three-wire system.

[0023]

According to the conventional ground return transport, the characteristics of a single-phase three-wire circuit are used to enable the reception of a transport signal without using a third-type ground wire at the receiving point. The disadvantages can be solved and higher quality data transmission can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a view for explaining a modified embodiment of the present invention.

FIG. 4 is a diagram for explaining the principle of the present invention.

[Explanation of symbols]

T, T ₂ ····· Single-phase three-wire transformer T ₀ , T ₁ ··· Detector OT ····· Injection transformer SV ····· Monitoring device MOD ··· ..Modulator DEM ... Demodulator F ... Filter

Claims (8)

(57) [Claims] 1. A carrier signal applied to a single-phase three-wire circuit having at least one end grounded via a ground wire of the circuit.
Carrier signal reception received on extension of the single-phase three-wire circuit
In the apparatus, the receiving side for receiving the carrier signal, the non-grounded side voltage pressurized adding two non-grounded path voltage of the single-phase three-wire path
Calculating means, and the added voltage from the non-ground side voltage adding means.
Detects the difference voltage between the single-phase three-wire circuit and the ground-side circuit voltage
Carrier signal comprising: a difference voltage detecting means.
Receiving device . 2. The non-ground side voltage adding means, wherein :
Is composed of multiple resistors with different resistance values.
The difference voltage detecting means is constituted by an operational amplifier.
The carrier signal receiving apparatus according to claim 1, wherein: 3. A carrier signal applied to a single-phase three-wire circuit via a ground wire of a single-phase three-wire circuit having at least one end grounded .
Carrier signal reception received on extension of the single-phase three-wire circuit
In the apparatus, the receiving side for receiving the carrier signal includes the single-phase three-wire power supply.
Non-ground side voltage summing the two non-ground side circuit voltages of the circuit
Calculating means, and the added voltage from the non-ground side voltage adding means.
The ground-side circuit voltage of the single-phase three-wire circuit is connected to the primary side of the transformer.
Applied to both ends, the difference between the secondary side of the transformer and the primary side
Voltage difference detecting means for detecting a voltage corresponding to the pressure,
An apparatus for receiving a carrier signal, comprising: 4. The non-ground side voltage adding means includes:
Is composed of multiple resistors with different resistance values
The carrier signal receiving device according to claim 3, wherein: 5. A carrier signal applied to a single-phase three-wire circuit, which is grounded at least at one end thereof , via a ground wire of the circuit.
A ground-side circuit and two non-ground-side circuits of the single-phase three-wire circuit;
Extension of a single-phase two-wire circuit tangent to one ungrounded circuit
In a carrier signal receiving apparatus for receiving a carrier signal, a receiving side for receiving the carrier signal applies the single-phase two-wire circuit voltage to a primary side of a single-phase three-wire transformer, and The middle point of the secondary side of the three-phase three-wire transformer is connected to the ground side of the primary side, and two non-connected parts of the single-phase three-wire section of the secondary side of the single-phase three-wire transformer are connected.
A non-ground side voltage adding means for adding a ground side circuit voltage;
Addition voltage from ground side voltage addition means and the single-phase three-wire circuit
And a difference voltage detecting means for detecting a difference voltage from the ground-side circuit voltage . 6. A carrier signal applied to a single-phase three-wire circuit via a ground wire of a single-phase three-wire circuit having at least one end grounded .
Carrier signal reception received on extension of the single-phase three-wire circuit
The method for receiving a single-phase three-wire signal on a receiving side receiving the carrier signal.
The two non-grounded circuit voltages of the circuit, and
Detects the difference voltage between the single-phase three-wire circuit and the ground-side circuit voltage
A method for receiving a carrier signal, comprising: 7. A carrier signal applied to a single-phase three-wire circuit via a ground wire of a single-phase three-wire circuit having at least one end grounded .
Carrier signal reception received on extension of the single-phase three-wire circuit
The method for receiving a single-phase three-wire signal on a receiving side receiving the carrier signal.
The two non-grounded circuit voltages of the circuit, and
The ground-side circuit voltage of the single-phase three-wire circuit is connected to the primary side of the transformer.
Applied to both ends, the difference between the secondary side of the transformer and the primary side
A carrier signal characterized by detecting a voltage corresponding to the pressure.
Receiving method . 8. A carrier signal applied to a single-phase three-wire circuit via a ground wire of a single-phase three-wire circuit having at least one end grounded ,
A ground-side circuit and two non-ground-side circuits of the single-phase three-wire circuit;
Extension of a single-phase two-wire circuit tangent to one ungrounded circuit
In the carrier signal receiving method for receiving on the length, on the receiving side receiving the carrier signal, the single-phase two-wire system
Circuit voltage is applied to the primary side of the single-phase three-wire transformer,
Connect the middle point of the secondary side of the line transformer to the primary side ground line.
Two single-phase three-wire circuits on the secondary side of the single-phase three-wire transformer
The earth side circuit voltage is added, and the added voltage and the single-phase three-wire circuit are added.
Detecting the difference voltage from the ground-side circuit voltage
The method of receiving the carrier signal .