JP3149312B2 - Distribution line carrier signal injection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a signal injection method in distribution line conveyance using a line between three-phase distribution lines as a transmission line of a command data signal.

[0002]

2. Description of the Related Art Distribution line transportation is a technology that is widely used in distribution system automation systems of electric power companies because existing distribution line paths can be utilized.
Centralized load control, switch control, collection of various distribution system management information, automatic meter reading, etc.

In the transmission of distribution lines, the transmission side injects a command data signal into the three phases of the three-phase distribution line at the power supply terminal in three phases, and the reception side transmits one line of any one of the three-phase lines. Generally, a method of detecting a command data signal from the control signal is used.

The receiving side is multi-connected on a distribution line as a signal transmission path, and operates in response to command data from the transmitting side. Therefore, the reliability of the transmitting device greatly affects the reliability of the entire system. This is an important factor in system design.

[0005]

The reliability of such a transmitting device can be improved by improving the reliability of a single device and by multiplexing the devices (a plurality of circuits having the same rating and function are mounted, and one If a failure occurs, switching to another system by using a switching circuit will be sufficient for practical use. However, multiplexing of devices has problems, especially in terms of the cost and shape of the main circuit. Was.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and solve the above problem.
Even if a failure occurs in a main circuit (amplifying circuit) for outputting a command data signal in the transmission device without multiplexing a transmission device for injecting a three-phase signal into each phase of the phase distribution line, the command data signal is output. An object of the present invention is to minimize the reduction in transmission reliability and maintain system functions.

[0007]

SUMMARY OF THE INVENTION According to the present invention, one of three independent main circuits of a transmitting apparatus for injecting three-phase signals into each phase of a three-phase distribution line has a failure. When this occurs, the same command data signal is injected a plurality of times by changing the phase order by using the main circuit of the remaining two phases, so that the command data signal received by the receiving device is kept at a certain level. It is characterized by being able to secure the above.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method for injecting a three-phase signal into each phase of a three-phase power distribution line. By injecting a signal, it is possible to detect a signal of a constant level even on the receiving side, and in this case, it is a method of actively utilizing the fact that a level difference occurs in the received signal in each phase. .

FIG. 1 is a general equivalent circuit diagram when a three-phase signal is injected into a distribution line. Where E ₁ , E ₂ ,
E ₃ is the voltage source of three-phase, represented by _{E 1 = E E 2 = Eexp} (-j · 2π / 3) E 3 = Eexp (-j · 4π / 3). Z ₁ , Z ₂ , and Z _m are signal coupling circuit impedances, and Z _TF is a distribution line impedance.
Note that U, V, and W represent the three-phase order.

When the main circuit is sound for all three phases, signals for each phase can be easily obtained by calculating the equivalent circuit of one phase obtained by converting Y in FIG. 1 as shown in FIG. _{That, EΔ RS = EY S -EY R} = √ (3) Z m / A · Eexp (-j · 5π / 6) Z TF (1) EΔ ST = EY T -EY S = √ (3) Z m / A · Exp (j · π / 2) Z _TF (2) EΔ _TR = EY _R −EY _T = √ (3) Zm / A · Exp (−j · π / 6) Z _TF (3) where A = Z ₁ Z _m + (Z ₂ + Z _TF ) Z _m + Z ₁ (Z
₂ + Z _TF ) On the other hand, when one phase of the main circuit is opened due to a fault, the signal level of one of the voltage sources E ₁ , E ₂ , and E ₃ in FIG. Opened by B and determined by calculating the current flowing through the distribution line with the remaining healthy two-phase voltage source. Hereinafter, in FIG.
Calculation is performed for the case where the main circuit of the phase is opened by the main circuit switching relay B.

FIG. 3 is an equivalent circuit diagram obtained by modifying the equivalent circuit of FIG. 1 in order to obtain the current flowing through E _{2. When} the current flowing in each phase is obtained, equations (4) to (6) are obtained. Become.

I _2RS = −Z _m (3A + Z _m ² ) E ₂ / [3A (3A + 2Z _m ² )] (4) I _2ST = Z _m E ₂ / 3A (5) I _2TR = −Z _m ³ E ₂ / [3A (3A + 2Z _m ^2)] When determined by (6) in the same manner E ₃ the current flowing through each ^{_{phase, I 3RS = Z m 3 E}} 3 / [3A (3A + 2Z _m ^2)] (7) I _3ST = - Z _m E ₃ / 3A (8) I _3TR = Z _m (3A + Z _m ² ) E ₃ / [3A (3A + 2Z _m ² )] (9) From each of equations (4) to (9), each phase at the time of one-phase failure is missing. Is obtained as follows.

E′Δ _RS = (I _2RS + I _3RS ) · 3Z _TF (10) E′Δ _ST = (I _2ST + I _3ST ) · 3Z _TF (11) E′Δ _TR = (I _2TR + I _3TR ) · 3Z _TF (12) The ratio of the signal level of each phase when the one-phase failure is lost to the three-phase soundness is obtained by comparing (1) to (3) with (10) to (12). (1) to (3) are the same level, and the following calculation is a calculation for obtaining only the level ratio. Therefore, the signal at the time of three-phase sound is expressed by EΔ = √ (3) Z _m / A
・ Represent by ( _EZTF ).

The level ratio of the _ST phase not related to the failure phase is: | E'ΔST / EΔ | = | [exp (−j · 2π / 3) −exp (−j · 4π / 3)] / √ (3) | = 1 (13), and the level does not decrease.

On the other hand, the levels of the RS phase and the TR phase related to the failed phase decrease at a certain ratio with respect to the normal state. A calculation example of the reduction rate is shown below.

The impedance of each unit used in the calculation is an empirical value for a specific signal frequency obtained from the actual device and the actual distribution system, and Z ₁ = 0.10-j 3.22 Z ₂ = 5.08-j7 .10 Z _m = 0 + j 2.30 Z _TF = 3.35 + j 3.10. As calculated by the impedance _{example, | E'Δ RS /EΔ|=|0.31+j0.63|=0.70 (14)} | E'Δ TR /EΔ|=|0.48+j0.08|=0.49 (15) It can be seen that the signal level of the RS phase is maintained at 70% of that in the normal state. In contrast, the level of the TR phase is reduced to 50%. Although this ratio changes depending on the impedance constituting the circuit, it shows almost the same tendency.

The above results are obtained when the voltage source is set as E ₁ = 1 E ₂ = Eexp (−j · 2π / 3) E ₃ = Eexp (−j · 4π / 3) If the phase sequence is changed and E ₁ = 1 E ₂ = Eexp (−j · 4π / 3) E ₃ = Eexp (−j · 2π / 3), it is clear from the relations (4) to (12). As described above, the level decrease rate of the RS phase and the level decrease rate of the TR phase are interchanged.

As described above, according to the present invention, when a failure occurs in a one-phase main circuit, a level difference is generated between the lines of each phase, and the relation of the level difference changes the phase order of the voltage source. It focuses on replacement, that is, when a failure occurs in the one-phase main circuit on the transmission side,
If the transmission side temporarily stops signal transmission, opens and disconnects the main circuit of the failed phase, transmits the same signal again, and further changes the phase order, then performs transmission. Since a signal is detected between any one of the three-phase distribution lines, the received signal level can be maintained at about 70% of that in the case where all three phases are sound, and the period until the fault is recovered In this case, it is possible to minimize a decrease in the reliability of data signal transmission.

FIG. 4 is a diagram showing an example of a data signal transmission pattern when the one-phase main circuit according to the present invention fails. FIG. 4 (a) shows an example of a command data signal having no response.
FIG. 4B shows a case of a command data signal having a response.

FIG. 5 is a circuit diagram showing an example of a transmitting apparatus for implementing the distribution line carrier signal injection method of the present invention.
FIG. 5A is a circuit diagram, and FIG. 5B is a diagram illustrating a main circuit drive signal for controlling the main circuit M by a control circuit. In FIG. 5A, B is a main circuit switching relay, C is
Is a control circuit, CT is a fault detection current transformer, and M is a main circuit.

In the same figure, assuming that the upper three control transistors are U ₁ , V ₁ and W ₁ and the lower three control transistors are U ₂ , V ₂ and W ₂ , respectively, FIG. As shown in the operation state diagram of the circuit control transistor, U ₁ → V ₁ → W ₁ is turned on with a phase difference of 120 °. The same applies to U ₂ → V ₂ → W ₂ ,
FIG. 6 shows the case of forward rotation, and in the case of reverse rotation, the relationship of phase advance / delay is reversed. In addition, U ₁ ← → U ₂ , V ₁ ← →
V ₂ , W ₁ ← → W ₂ alternately turn on and off.
However, as shown in FIG. 6, a slight delay is provided to prevent a short circuit state due to simultaneous ON.

[0022]

As described above, according to the present invention,
When a failure occurs in one main circuit among three independent main circuits of a transmission device that injects a three-phase signal into each phase of a three-phase distribution line, a sound main two-phase main circuit is provided. Is used to inject the same command data signal a plurality of times while changing the phase order, so that the command data signal received by the receiving device can be maintained at a constant level. Even if a failure occurs in a main circuit that outputs a command data signal in the transmitting device without multiplexing a transmitting device that injects a three-phase signal into each phase, a decrease in reliability of command data signal transmission is minimized. Limit and maintain system functions.

[Brief description of the drawings]

FIG. 1 is a general equivalent circuit diagram when a three-phase signal is injected into a distribution line.

FIG. 2 is an equivalent circuit diagram of one phase converted into Y.

FIG. 3 is an equivalent circuit diagram obtained by modifying the equivalent circuit of FIG. 1;

FIG. 4 is a diagram showing an example of a data signal transmission pattern when a one-phase main circuit according to the present invention has a failure.

FIG. 5 is a circuit diagram illustrating an example of a transmission device that implements the distribution line carrier signal injection method of the present invention.

6 is an operation state diagram of a main circuit control transistor in FIG.

[Explanation of symbols]

B main circuit closing relay C control circuit CT fault detection current transformer E _1, E _2, E ₃ voltage source M main circuit R phase S phase T phase U phase U _1, U ₂ control transistor V-phase V _1, V ₂ control transistor W phase W ₁ , W ₂ control transistor Z ₁ , Z ₂ , Z _m signal coupling circuit impedance Z _TF distribution line impedance

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeyuki Hashimoto 3-7-1, Ichibancho, Aoba-ku, Sendai City, Miyagi Prefecture Tohoku Electric Power Co., Inc. (72) Inventor Hiroshi Hasegawa 2-2-2 Higashi-Gotanda, Shinagawa-ku, Tokyo No. 7 Osaki Electric Industry Co., Ltd. (72) Kyoichi Koyama 2-7-2 Higashi Gotanda, Shinagawa-ku, Tokyo 2-7 Osaki Electric Industry Co., Ltd. (72) Hiroyuki Kurata 2-2-2 Higashi Gotanda, Shinagawa-ku, Tokyo No. 7 Inside Osaki Electric Industry Co., Ltd. (56) References JP-A-58-66541 (JP, A) JP-A-60-148247 (JP, A) JP-A-3-503345 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 3/50-3/60

Claims (1)

(57) [Claims] 1. A distribution line carrier signal injection method for injecting a command data signal by superimposing a carrier wave on a commercial frequency by using a line between three-phase distribution line lines as a signal transmission line. When a failure occurs in one of the three independent main circuits of the transmission device that injects three-phase signals into the transmission device, the same command data is transmitted using the remaining two-phase main circuits that are sound. A method for injecting a distribution line carrier signal, wherein a signal is injected a plurality of times by changing the phase sequence.