JPS61256835A - Distribution line carring equipment - Google Patents

Abstract

PURPOSE:To attain communication with high quality by providing an impedance network between a distribution line at the side of a repeater station and ground and causing the series resonance state at communication so at to improve the quality of a signal current remarkably. CONSTITUTION:When a high frequency transmission signal is fed to ground from a transmitter 31 or 32 of a terminal station based on a data transmission request from the side of the repeater station, a signal current flows in a direction of the side of a pole transformer having a low impedance, that is, in a direction shown in dotted or full line arrow. Since an impedance ZN causes resonance with respect to the signal frequency and a low impedance is given, the flowing current flows to ground via the impedance network. In detecting the sending current by three CTs 5 provided to b, n, c phase lines, the sending current is increased much larger than that of the case lines, the sending current is increased much larger than that of the case without the insertion of the impedance network 6ZN. Thus, the sending current flowing to a receiver 4 is increased to improve the S/N.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to the operation of electrical equipment connected to a power distribution system, such as monitoring and controlling the system and load equipment, automatic meter reading, or collecting various management information. The present invention relates to a distribution line conveying device.

[Conventional technology]

With the recent development of power distribution systems, the use of electric power has been increasing because electric power is an extremely useful medium both as energy and as an information network.

In other words, the power distribution system is characterized by its large-scale configuration and the fact that various electrical devices are connected to its loads.

In order to automate the operation of such large-scale and complex power systems, so-called power distribution automation devices are being put into practical use. Among these, power distribution line conveying devices that superimpose high-frequency current or voltage on power distribution lines are gradually attracting attention.

Figure 3 shows a configuration diagram of a conventional 2-wire ground-to-ground return distribution line carrier system. In the figure, 1 is a pole transformer, 2 is a single-phase 3-wire distribution line, and 3 is a transmitter installed at a terminal station. Each of the transmitters 31 and 32 is connected to a single-phase three-wire distribution line 2 consisting of A, N, and C via transmitting side coupling devices 30b and 30c. 4 is a receiving device of a relay station, and a receiver coupling device 40-1
40-2 to respective receivers 41.42.

Next, the operation will be explained. First, as a signal transmission method, a signal of the same polarity is sent from one of the transmitting devices 3, which is a terminal station, to the ground via the transmitting side coupling device 30b or 30c to the two phases of the single-phase three-wire distribution line 2. Apply voltage. By this operation, the signal voltage propagates in parallel toward the receiving end through the two wires, and the corresponding two-wire receiving side coupling device 40-1.40
-2 to the receiver 41 or 42. For example, the applicable frequency in this case is sufficiently higher than the system frequency and is output from a separately prepared oscillation circuit. Single-phase 3-wire arrangement with V-connection! In a system where there is a separate load on the b-n phase and the c-n phase, as in the case of line 2, two types of transmitters 31 and 32 are installed to improve the signal-to-noise ratio (S/N). A method is adopted in which two types of receivers 41 and 42 are arranged and reception is performed by whichever pair is better.

[Problem that the invention seeks to solve]

Conventional power distribution line carrier devices are configured as described above, and a signal is applied to two wires of a single-phase three-wire power distribution line from a separately prepared oscillation circuit at a sufficiently high frequency different from the commercial frequency voltage of the power line. Since the carrier method was to propagate the signal as a wave and detect it on the receiving side, depending on the signal power application/detection device, the signal transmission ratio could not be improved and the equipment would become large and expensive.

In addition, the neutral point n is usually grounded near the receiving device, and even if the transmitting end injects signal power from one point, the receiving device connects it to three points, S, S, and n. There are problems in that the transmitted signal current is divided into three points, reducing the signal transmission rate, and is also affected by the impedance of the pole transformer.

This invention was made in order to solve the above-mentioned problems, and involves establishing a ground return path between a transmitting device, which is a terminal station, and a receiving device, which is a relay station, and injecting signal power between them. The purpose of the present invention is to provide a distribution line transportation system that enables highly efficient signal transmission and reception.

[Means for solving problems]

The distribution line transport device according to the present invention includes a relay station provided with an impedance Φ network and a transmitting device on the side of a pole transformer that feeds power to a low-voltage distribution system, and a transmitting device provided in a terminal station of a load customer, so that both stations are busy. A ground return path is provided, and signal power is injected from the terminal station's transmitting device to the ground, causing series resonance in the impedance network of the relay station, and the transmitting current is detected by the receiving device.

[For production]

In order to lower the high frequency impedance during communication and improve the 8/N ratio, the carrier device using the power distribution line in this invention has an impedance network consisting of a plurality of filters between the power distribution line on the relay station side and the ground, and The series resonance is reproduced, and at that time, the high 8
/N ratio signal current is detected.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 3 are designated by the same reference numerals. In FIG. ), 6 is an impedance network for grounding, which has frequency characteristics of blocking fundamental waves and passing signal frequencies, which will be described later. It also has a contact P that opens and closes the grounding circuit as necessary.

Next, the operation of the present invention will be explained below. First, when a high frequency transmission signal is applied to the ground from the transmitting device 31 or 32 of the terminal station based on a data transmission request from the relay station side, a low impedance column A signal current flows in the direction toward the upper transformer, that is, in the direction indicated by the dotted or solid arrow. This inflow current is b - n as shown in Figure 1.
-C phase flows leftward in the figure, but if there is no grounding impedance network ZN6, it will depend on the impedance of the pole transformer 1 and the ground point (neutral point) On.

Generally, a transformer has leakage reactance, so the inflow current is limited by the leakage reactance, and the higher the signal frequency, the greater the effect of attenuation.

Here, the impedance φ network 6 denoted by zN
When zN is inserted, as described above, zN resonates with the signal frequency and exhibits a low impedance, so that the inflow current flows to the ground via the impedance network 6.

If this transmission current is detected by the three CT5s arranged in the A, N, and C phases, it is clear that the transmission current will be extremely large compared to the case where the impedance network 6ZN is not inserted. Therefore, the transmission current flowing into the receiving device 4 becomes thicker (the signal-to-noise ratio improves).

In this case, the CT50 frequency characteristics are a problem, but normally, if carefully designed and manufactured, the frequency characteristics of the pole transformer 1 with an iron core are flat over a bandwidth of loKHz or higher.
Even in the band used as the pruning signal frequency, it does not cause a decrease in detection sensitivity.

By inserting the impedance φ network 6ZN and transmitting the carrier wave in this way, the sensitivity of the received current can be improved.

FIG. 2 is a detailed diagram of the impedance network 6ZN according to the present invention. In the figure, 61b and 61c are fundamental frequency blocking and high frequency passing filters inserted between the b and c phases and the ground, respectively; Reference numeral 62c denotes an F-wave device which is inserted between the ground in series with the filters 61b and 61c and resonates in series with the signal frequency. The four sets of door transducers are residually connected at the intersection 63 and grounded to the ground 6E via the contact 64.

Next, when receiving a signal, the contact 64 is closed in response to a command from the receiving device 4R to form a series resonant circuit for the signal frequency. Therefore, the signal current flows through the impedance network 6 and is detected by the CT 5 together with the leakage current flowing through the ground point N of the pole transformer 1 to earth.

The high frequency impedance seen on the left side of the diagram due to the CT5 as in the case of multiplexing is extremely small compared to the case without the impedance Φ network 6ZN, so the current of the CT5 becomes more uniform and the 8/N ratio during reception is greatly improved. Further, even when the interconnection line 9 is drawn out from the grounding point N and connected to ground, the above-mentioned effect is not diminished. Also, impedance
The filters in the network 602 can be arbitrarily selected depending on the load condition.

〔Effect of the invention〕

As described above, according to the present invention, in order to reduce the high-frequency impedance of the relay station side to the ground during communication of carrier signal current, an impedance network is provided between the wiring fJLH on the relay station side and the ground, and series resonance occurs during communication. Since the high-frequency signal current is generated at the receiving end of the relay station and the signal current is significantly improved, the high-frequency signal current is
It can be detected by the N ratio and has the effect of enabling high quality communication.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the invention 2a! FIG. 2 is a detailed diagram of the impedance network on the relay station side shown in FIG. 1, and FIG. 3 is a configuration diagram of a conventional distribution line transportation device. In the figure, 1 is a pole/overhead pressure vessel, 2 is a single-phase 3-wire distribution line,
3 is a transmitting device, 4 is a receiving device, and 5 is a CT. 6 is an impedance network, 61b. 61c is a filter, 62b and 62c are F-wave devices, 64 is a contact, and 6E is a ground.

Claims (3)

[Claims] (1) A pole transformer that feeds power to the low-voltage distribution system, a receiving device on the relay station side connected to the pole transformer via a CT, and a receiver connected to the pole transformer via a distribution line. A power distribution line carrier device comprising a transmitting device on a terminal station side, and an impedance network connected between a power distribution line on the relay station side and the ground to generate resonance with a signal current during communication and lower high frequency impedance. (2) The configuration of the impedance network is that it is connected directly to the neutral point of the single-phase three-wire distribution line, and the other two wires are grounded through filters, so that selection can be made depending on the state of the load system. A power distribution line conveying device according to claim 1, characterized in that: (3) The distribution line conveying device according to claim 1, characterized in that a contact point is provided between the impedance network and the ground, so that it can be controlled by commands from the receiving device as necessary.