JPH01286530A - Distribution line carrier system - Google Patents

Abstract

PURPOSE:To improve the data transmission speed and to maintain the reliability against noise by increasing number of significant states of modulation when noise state of a distribution line is excellent and decreasing the number of significant states of modulation when noise state of the distribution line is not excellent. CONSTITUTION:A carrier signal is formed by a guard signal 1, a start bit 2, a modulated designation signal 3, and a data signal 4 and is a signal subject to frequency shift modulation. Then the modulation designation signal 3 in succession to the start bit 2 is modulated by a binary code designating the number of significant state of modulation of the data signal 4, the data signal 4 in succession to the modulation designation signal 3 is modulated by a code of number of the designated significant state by the modulation designation signal 3 and the designation of the significant state number is revised in response to the state of the distribution line. That is, when the noise state of the distribution line is excellent, number of significant state of modulation is increased and when the noise state of the distribution line is not excellent, the number of significant state of modulation is decreased. Thus, the data transmission speed is improved and the reliability against noise is maintained.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a distribution line carrier system in which data is transmitted by frequency shift keying using a low frequency carrier signal and using a signal transmission path between the lines of a distribution line. This is related to the improvement of.

(Background of the Invention) This type of distribution line conveyance system includes a ripple control system and a current answerback system, which are widely used for load concentration control, switch control, etc. The former is a method in which a voltage signal is superimposed on the busbar of a power distribution substation to transmit command data, and the latter is a method in which data is sent back to the substation as a current signal from the end of the power distribution system. In both cases, the center frequency of the carrier signal is a relatively low frequency of about 100 to 600 Hz, which has good signal transmission characteristics.

Conventionally, the data transmission speed of these two systems has been limited to 20 to 30 b/s for the following reasons, which is a major obstacle in expanding the application of the distribution line transport system.

■ Harmonic voltages and currents of the commercial frequency exist as noise on power distribution lines, and the signal transmission band is set to avoid this harmonic noise, so the bandwidth is limited.

■ Resonance sharpness Q of the resonant circuit that couples the signal to the distribution line
However, due to problems such as reduced coupling efficiency and heat generation due to signal power,
Since it cannot be made too small, the bandwidth is still limited.

In conventional distribution line transportation, only 2 modulations are performed,
By adopting multilevel modulation, which is widely used in general data communication systems, it is possible to improve the data transmission speed in the same band as before. However, when employing multilevel codes for distribution line transportation, there are the following problems.

(2) When the signal level is the same as that of the conventional method, the level difference between each level of modulation using a multilevel code is smaller than that of a binary code, so reliability against noise is lowered.

- Power distribution lines have higher noise levels and fluctuations than general communication lines, and the reliability of modulation and demodulation using multilevel codes may deteriorate significantly.

(Purpose of the invention) The object of the present invention is to solve the above-mentioned problems.

It is an object of the present invention to provide a distribution line transport system that can improve data transmission speed and maintain reliability against noise.

(Features of the Invention) In order to achieve the above object, the present invention forms a carrier signal by frequency shift keying by a synchronization start signal, a modulation designation signal, and a data signal, and provides the modulation designation signal following the synchronization start signal. , the data signal is modulated by a binary code that specifies the number of significant states of modulation, the data signal following the modulation designation signal is modulated by the sign of the number of significant states designated by the modulation designation signal, and the distribution line The designation of the number of significant states is changed according to the state of the distribution line, and when the noise condition of the distribution line is good, the number of significant states of modulation is increased to increase the transmission speed and reduce the noise of the distribution line. It is characterized in that when the condition is bad, the number of significant states of modulation is reduced to maintain reliability against noise.

In addition, when a carrier signal is returned from a slave station to the master station in response to a carrier signal from the master station, return modulation that specifies the significance of the modulation of the return data signal is performed in the carrier signal from the master station. Including the designated signal, the number of significant states of modulation of the carrier signal from the slave station to the master station is also changed according to the state of the power distribution line,
It is characterized by changing the data transmission speed.

(Embodiment of the Invention) FIG. 1 shows an example of the signal format of a carrier signal according to the present invention sent from a master station to a slave station.

This carrier signal consists of a guard signal 1, a start bit 2, a modulation designation signal 3, and a data signal 4, and is a one-frequency shift keyed signal. Guard signal 1 has a low frequency fL (
The start bit 2 is a signal transmitted at a high frequency fl (space) among the frequencies of the signal transmission band, and the guard signal 1 and start bit 2 constitute the synchronous start signal of the present invention. do. The modulation designation signal 3 is a signal modulated by a binary code that designates the number of significant states of modulation of the data signal 4, and in the example of FIG.
For example, if the binary code of modulation designation signal 3 is OO, the number of significant states of modulation of data signal 4 is 2 (binary modulation), and if the bit is 10, the number of significant states is 4 (4-value modulation). ), Ol, the number of significant states is predetermined as 8 (8-value modulation). The number of significant states of modulation of the data signal 4 designated by the modulation designation signal 3 is changed depending on the state of the power distribution line. That is, if the condition of the power distribution line is good, the number of significant states is changed to a large number, and if the condition of the power distribution line is bad, the number of significant states is changed to a small number. In addition,
Considering the stability of transmission characteristics, accuracy on the demodulation side, etc., it is difficult to implement higher than 8 values.

The data signal 4 is modulated with the sign of the number of significant states specified by the modulation designation signal 3. The frequency arrangement in that case is as shown in FIG.

Note that fo is the center frequency of the signal transmission band.

In the case of 8-level modulation, the frequency change state of the carrier signal is
as shown in the figure. The sampling point on the receiving side is set based on start bit 2, which is the center of each bit.

An example of the apparatus for carrying out the present invention is shown in FIGS.
The figure shows the configuration of a master station. The master station is composed of a solid device 5 installed at a branch or business office of an electric power company, and a substation device 6 installed at a substation. The solid device 5 has an operation panel 7, C
It includes a PU 8 and a line control circuit 9. The substation device 6 is connected to the solid device 5 by a dedicated communication line IO, and includes a transmitting circuit 11, a coupling circuit 12, and a receiving circuit 13. The coupling circuit 12 is coupled to a bus bar 15 connected to the secondary side of the main transformer 14 of the substation. The receiving circuit 13 is connected on the secondary side to an auxiliary current transformer 17 that is connected to the secondary side of the feeder current transformer 16 .

FIG. 5 shows the arrangement of a slave station for switch control. The slave station 18 is connected to the secondary side of the distribution transformer 19 and controls the opening and closing of the line switch 21 that opens and closes the feeder 20. do.

FIG. 6 shows the configuration of the slave station 18. The slave station 18 includes a receiving circuit 22, a transmitting circuit 23, and a control circuit 24. 25
2 is a low voltage distribution line connection terminal, 26 is a control output terminal, and 27 is a monitoring input terminal.

Next, the operation will be explained. In the solid equipment 5, when a command to transmit a carrier signal instructing to open the track switch 21 is issued by operating the operation panel 7, the CPU 8 sends data TxD indicating the command to open the track switch 21 to the line. The signal is sent to the control circuit 9.

The line control unit 9 determines the noise state of the power distribution line based on the response status of the slave station 18, the time of day, etc., and sends the modulation designation signal 3.
At the same time, the signal format of the carrier signal shown in FIG. 1 is sent to the transmission circuit 11 of the substation equipment 6. The transmitting circuit 11 transmits a frequency shift keyed carrier signal according to the signal format, and superimposes it on the commercial frequency of the bus 15 via the coupling circuit 12.

In the slave station 18, the receiving circuit 22 detects the guard signal l, demodulates the zero-order modulation designation signal 3 that is synchronized when the guard signal l ends and switches to the start bit 2,
The number of significant states of modulation of the data signal 4 is determined based on the number of significant states determined at the zeroth order, and the data signal 4 is demodulated, and the data of the command to open the line switch 21 is transferred to the control circuit 24.

The signal format shown in Figure 1 is used for the downlink command signal sent from the master station to the slave station, but on the other hand, the uplink transmission signal sent from the slave station to the master station is Since the response situation is not known, the number of significant states of modulation cannot be uniquely determined on the slave station 18 side. Therefore, in the present invention, the number of significant states of modulation of the return data signal is specified in the downlink command signal. A specified signal is added. FIG. 7 shows an example of the signal format of the downlink command signal and the uplink return signal.

In the downlink command signal, a return modulation designation signal 28 is added after the data signal 4. The return modulation designation signal 28 is a signal modulated by a binary code that specifies the number of significant states of modulation of the return data signal 29 in the uplink transmission signal. Note that the modulation designation signal 3 in the upstream return transmission signal has the same number of significant states as the return modulation designation signal 28.

FIG. 8 shows the operation of the line control circuit 9 when using the signal format of FIG. 7. When data TxD is input from the CPU 8, a modulation designation signal 3 and a return modulation designation signal 2
The number of significant states of 8 is determined to be the maximum (8 values), and the data signal 4
is modulated with the sign of the maximum number of significant states. After transmitting the downlink command signal, it starts counting a fixed reception time and waits for reception of the uplink transmission signal. When the reception circuit 13 receives the uplink transmission signal normally, it transfers the received data to the RxD1 CPU 8. If there is no normal reception within, for example, 1/3 of the reception time, it is determined that the condition of the power distribution line is not good, and when there is no response, only the number of significant states of modulation designation signal 3 is decreased (4 value), and if there is a response but there is an error in the returned data, only the number of significant states of the returned modulation designation signal 28 is decreased (
4 values) and send again. Even so, if there is no normal reception within, for example, 2/3 of the reception time, the number of significant states of the modulation designation signal 3 or return modulation designation signal 28 is further decreased (to binary) and transmitted again. If there is still no normal reception within the reception time, the process is repeated again from the maximum number of significant states (8 values).

FIG. 9 shows the operation of the receiving circuit 13 of the substation equipment 6. The receiving circuit 13 detects the guard signal 1 of the uplink transmission signal, and synchronizes when the guard signal 1 ends and switches to start beat and t 2. The zero-order modulation designation signal 3 is demodulated and the number of significant states of modulation of the return data signal 29 is determined.The zero-order return data signal 29 is demodulated and it is determined whether or not there is an error in the return data. If there is no error, the returned data is transferred to the line control circuit 9, and the line control circuit 9 determines that normal reception has been made. If there is an error, the error code is transferred to the line control circuit 9, and the line control circuit 9 changes only the number of significant states of the return modulation designation signal 28 as described above.
and send it again.

FIG. 1O shows the operation of the receiving circuit 22 of the slave station 18. The receiving circuit 22 detects the guard signal l, and synchronizes when the guard signal l ends and switches to the start bit 2.0-order modulation designation signal The data signal 4 is demodulated to the 0th order, and if there is no error in the data, the number of significant states of the return modulation designation signal 28 is determined, and the transmitting circuit Transfer to 23. The data is then transferred to the control circuit 24. The control circuit 24 performs control according to the data, and the transmitting circuit 23 modulates the return data with the code of the number of significant states specified by the return modulation designation signal 28, and transmits an uplink transmission signal.

(Effect of the invention) As explained above, according to the present invention as set forth in claim 1,
A carrier signal by frequency shift keying is formed by a synchronization start signal, a modulation designation signal, and a data signal, and the modulation designation signal following the synchronization start signal is formed by a binary code that designates the number of significant states of modulation of the data signal. modulating the data signal following the modulation designation signal with a sign of the number of significant states designated by the modulation designation signal;
The designation of the number of significant states is changed according to the condition of the distribution line, and if the noise condition of the distribution line is good, the number of significant states of modulation is increased to increase the transmission speed, and the number of significant states of the distribution line is increased. When the noise condition is bad, the number of significant states of modulation is reduced to maintain reliability against noise, which improves data transmission speed and maintains reliability against noise. be able to.

Further, according to the present invention as set forth in claim 2, when a carrier signal is returned from the slave station to the master station in response to a carrier signal from the master station, the return data signal is included in the carrier signal from the master station. Including a return modulation designation signal that designates the number of significant states of modulation,
The number of significant states of modulation of the carrier signal from the slave station to the master station is also changed according to the state of the power distribution line, and the data transmission speed is changed. Transmission speed can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the signal format of the carrier signal used in the present invention, FIG. 2 is a diagram showing frequency allocation when the number of significant states of modulation of the carrier signal used in the present invention is changed, and FIG. 4 is a block diagram showing an example of the configuration of a master station implementing the present invention, and FIG. 5 is a connection diagram showing the arrangement of slave stations implementing the present invention.
FIG. 6 is a block diagram showing an example of the configuration of the slave station, FIG. 7 is a diagram showing another example of the signal format of the carrier signal used in the present invention, and FIG. 8 is a block diagram showing the operation of the line control circuit of the master station. FIG. 9 is a flowchart showing the operation of the receiving circuit of the master station, and FIG. 10 is a flowchart showing the operation of the receiving circuit of the slave station. 1... Guard signal, 2... Start bit, 3... Modulation designation signal, 4... Data signal, 5... Solid Equipment, 6...Substation equipment, 7...Operation panel, 8...CP
U, 9... Line control circuit, 11... Transmitting circuit, 13... Receiving circuit, 18......
Slave station, 22... Receiving circuit, 23... Transmitting circuit, 24... Control circuit, 28...
Return modulation designation signal, 29...Return data signal. Patent Applicant Osaki Electric Industry Co., Ltd. Representative Minoru Nakamura Fig. 1 2 Constant modulation section Variable number of significant states section Dark Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Return data signal return section - Evening signal Fig. 8 Fig. 9 Lotus〉 ] Distribution - 2] --- 2 @ Demodulation 1 1 1 Number of significant states Undefined 1 To the transmitting circuit 1 To the control circuit

Claims (2)

[Claims] (1) In the distribution line carrier method, in which the lines of the distribution line are used as signal transmission paths and data is transmitted by superimposing a carrier signal based on frequency shift modulation on the commercial frequency, the carrier signal is used as a synchronous start signal and a modulation designation signal. and a data signal, the modulation designation signal following the synchronization start signal is modulated by a binary code that designates the number of significant states of modulation of the data signal, and the data signal following the modulation designation signal is modulated by the data signal. 1. A distribution line conveyance system characterized in that modulation is performed using the sign of the number of significant states specified by a modulation designation signal, and the designation of the number of significant states is changed depending on the state of the distribution line. (2) In the distribution line carrier method, data is transmitted between the master station and the slave stations by using the lines of the distribution line as a signal transmission path and superimposing a carrier signal by frequency shift keying on the commercial frequency, from the master station to the slave station. A carrier signal to a slave station is formed by a synchronization start signal, a modulation designation signal, a data signal, and a return modulation designation signal, and the modulation designation signal following the synchronization start signal designates the number of significant states of modulation of the data signal. The data signal following the modulation designation signal is modulated by a binary code, and the data signal following the modulation designation signal is modulated by a sign of the number of significant states designated by the modulation designation signal, and the return modulation designation signal is modulated by a significant state of the modulation of the return data signal. A carrier signal from the slave station to the master station is formed by a synchronization start signal, a modulation designation signal, and a return data signal, and the modulation designation signal following the synchronization start signal is modulated by a binary code that specifies the number. The return data signal following the modulation designation signal is modulated by a binary code representing the number of significant states designated by the modulation designation signal, and the return data signal is modulated by the code of the number of significant states designated by the modulation designation signal. A power distribution line transport system characterized in that the designation of the number of significant states is changed at a station according to the state of the power distribution line.