JPH078070B2 - Time synchronization method in remote monitoring device - Google Patents

Description

The present invention relates to a method for synchronizing the times of clocks installed in a master station and a slave station in a remote monitoring device.

[Prior Art] FIG. 4 is a diagram for explaining a time synchronization method in a conventional distant monitoring device disclosed in, for example, Japanese Patent Laid-Open No. 56-116199, in which 0 is a parent. Stations, 1 and 2 are slave stations, GP is a display panel showing the status of each slave station, CD is a control console for issuing control commands to each slave station 1, 2 and TW is a typewriter that records operations and data. , CP ₀ is an arithmetic processing circuit, DO ₀ is an output circuit, DI ₀ is an input circuit, TC is a typewriter control circuit, C
L ₀ is a master clock circuit, TR ₀ is a code transmission / reception circuit, and MD ₀ is a modulation / demodulation circuit.

In the slave stations 1 and 2, the symbols CP ₁ and CP ₂ are arithmetic processing circuits and M
D ₁ and MD ₂ are modulation / demodulation circuits, TR ₁ and TR ₂ are code transmission / reception circuits, D
I ₁ and DI ₂ are input circuits, DO ₁ and DO ₂ are output circuits, and CL ₁ and CL ₂ are child clock circuits. Further, L ₁ and L ₂ are signal transmission lines connecting the master station 0 and the slave stations 1 and 2, respectively.

Next, a method for synchronizing the clocks of the master station 0 and the slave stations 1 and 2 will be described. At the time of time synchronization, the arithmetic processing circuit CP ₀ of the master station 0 transmits the time t ₀ to be set (for example, 0: 00: 00: 00 ms). Each of the slave stations 1 and 2 receives this, stores the time t ₀ to be set by the arithmetic processing circuits CP ₁ and CP ₂ , and waits for the next setting command.

The master station 0 issues a setting command signal before a preset time τ millisecond which is considered to correspond to the transmission delay time to each slave station 1, 2, and when this arrives at the slave stations 1, 2, the arithmetic processing circuit C
P ₁ and CP ₂ set their respective child clocks CL ₁ and CL ₂ at time t ₀ .

[Problems to be Solved by the Invention] However, since the conventional time synchronization method in such a remote monitoring device is configured as described above, the expected transmission delay time τ millisecond is a fixed value. If the signal transmission path changes due to, and the transmission delay time changes,
There is an error in the clocks of the master station and slave stations. In recent years, in order to increase the reliability of the signal transmission line, two or more signal transmission lines such as a regular line and a detour line are provided, and if one fails, it is automatically switched to the other. A switching device may be provided on the way, but in this case, the transmission delay time may change every time.

On the other hand, as the power system becomes more sophisticated, the operating time of protective relays, etc. has become shorter, and the error due to the difference in the above-mentioned predicted transmission delays cannot be ignored in the accident analysis.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a time synchronization method in a remote monitoring device capable of automatically synchronizing clocks of a master station and a slave station. To do.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a remote monitoring device according to claim 1, wherein the remote station has clocks in the master station and the slave station. The time setting signal and the setting command signal are transmitted to the slave station, and the slave station stores the time setting signal in the memory, corrects the clock in the slave station by the setting command signal, and transmits the time setting signal next time. When the time is corrected or in the slave station, the correction operation based on the difference between the time of the time setting signal and the time of the clock in the slave station immediately before the correction is performed until the difference disappears.

In claim 2, when the slave station receives the setting command signal, it transmits the clock in the slave station immediately before correction to the master station, and the master station receives the time from the slave station and the time of the time setting signal. The time of the time setting signal to be transmitted to the slave station next time is corrected so that the difference between
The time setting signal and the time information are exchanged until the difference disappears.

In claim 3, the difference between the time of the time setting signal and the time of the clock of the slave station immediately before the correction is accumulated many times on the slave station side, and the slave station calculates and receives the correction value based on the accumulated data and receives it. The time of the time setting signal is corrected by the correction value.

[Operation] In the time synchronization method in the remote monitoring device according to the present invention, the set time signal is corrected based on the difference between the set time signal including the transmission delay time sent from the master station and the time of the clock of the slave station, As a result, the master station clock and the slave station clock are gradually and automatically synchronized.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 is a system block diagram showing a distant monitoring device for carrying out a time synchronization method as an embodiment of the present invention. In FIG. 1, 0 is a master station, 1 and 2 are slave stations, and a GP. Is a display board showing the status of each slave station, CD is a control console for issuing control commands to each slave station 1, 2, TW is a typewriter for recording operations and data, CP ₀ is an arithmetic processing circuit, DO ₀ Is the output circuit,
DI ₀ is an input circuit, TC is a typewriter control circuit, CL ₀ is a master clock circuit, MEM ₀ is a memory, D ₀₁ and D ₀₂ are demodulation circuits, M ₀₁ and M ₀₂ are modulation circuits, and R ₀₁ and R ₀₂ are codes. The receiving circuit and S ₀₁ and S ₀₂ are code transmitting circuits.

In the slave stations 1 and 2, the symbols CP ₁ and CP ₂ are arithmetic processing circuits and DI
₁ , ₁ and DI ₂ are input circuits, DO ₁ and DO ₂ are output circuits, and CL ₁ and CL ₂ are child clock circuits. MEM ₁ and MEM ₂ are memories, D ₁ and D ₂ are demodulation circuits,
M ₁ and M ₂ are modulation circuits, and S ₁ and S ₂ are code transmission circuits. Further, L ₁ and L ₂ are signal transmission paths connecting the master station 0 and the slave stations ₁ and ₂ , respectively.

Next, the operation will be described. In slave station 1 or 2,
The operating signal of the protective relay, the status signal of the breaker, etc. are input through the input circuit DI ₁ or DI ₂ , and the occurrence time is read from the slave clock circuit CL ₁ or CL ₂ of each slave station 1, ₂ and It is transmitted to the master station 0 together with the occurrence event. Therefore,
When the slave clocks of each slave station are not synchronized, the master station 0
Since the information sent from the slave station cannot be arranged in the order of occurrence, the operator's judgment may be erroneous.

Therefore, the time t ₀ (day,
(Hour, minute, second, millisecond) and setting command signal are transmitted to each slave station. At this time, the time t ₀ to be set is the time of the master clock plus the transmission delay time from the master station 0 to the slave station and the time from transmitting the time to be set to transmitting the setting command signal. .

As shown in FIG. 2, the slave station stores the time t ₀ to be set in the memories MEM ₁ and MEM ₂ and waits for a setting command signal. When the setting command signal is received, the time of the child clocks CL ₁ and CL ₂ is rewritten to t ₀ , but the time of the child clocks CL ₁ and CL ₂ immediately before rewriting is transmitted to the master station 0 and then rewritten.

The master station 0 compares the time t ₀ to be set transmitted to the slave station with the times t ₁ and t ₂ immediately before rewriting transmitted from the slave station. This difference is the difference between the time of the child clocks CL ₁ and CL ₂ considered by the master station 0 and the time of the actual child clock, and the next time t ₀ ′ to be set is corrected so that this difference becomes smaller. To do.

Since there is a risk of hunting if the correction is performed once, it is necessary to correct the average of the errors of the past tens of times or to correct the error by a fraction (that is, reduce the gain). The error is controlled so as to gradually approach zero by the method.

In the above embodiment, the example in which the time information immediately before rewriting is sent to the master station to calculate the correction is shown. However, as shown in FIG. 3, the slave stations have memories MEMO ₁ and MEMO ₂ . The difference between the time to be set sent from the master station and the time on the slave clock immediately before rewriting is stored for the past tens of times, and the correction value is calculated by the correction value calculation circuits AC ₁ and AC ₂ based on these data. Then
This correction value may be added to the information sent from the master station and used as the time to be set.

Further, as the method of calculating the correction value, the method of averaging the errors of several tens of times in the past has been described, but it goes without saying that a necessary transfer function may be passed in order to have a stable system.

As described above, according to the present invention, the correction of the transmission delay time and the like is automatically corrected, so that the signal transmission route is changed or the delay time in the middle of the transmission path is changed. Even in this case, there is an effect that the clock of the master station and the clock of the slave station can be automatically synchronized.

[Brief description of drawings]

1 to 3 show an apparatus for carrying out a time synchronization method in a remote monitoring apparatus as an embodiment of the present invention. FIG. 1 is a system block diagram thereof, and FIG. 2 is a slave station side thereof. FIG. 3 is a block diagram for explaining the function of FIG. 3, FIG. 3 is a block diagram showing another example for explaining the function on the slave station side, and FIG. 4 shows a time synchronization method in a conventional remote monitoring device. It is a systematic block diagram which shows the apparatus for implementing. In the figure, 0 ... Master station, 1, 2 ... Slave station, AC ₁ , AC ₂ ... Correction value calculation circuit, CD ... Control console, CL ₀ ... Master clock circuit, CL ₁ , CL ₂ ... Slave clock circuit, CP ₀ , CP ₁ , CP ₂ … Operation processing circuit, D ₁ ,, D ₂ , D ₀₁ , D ₀₂ …
Demodulation circuit, DI ₀ , DI ₁ , DI ₂ ... Input circuit, DO ₀ , DO ₁ , DO ₂ ... Output circuit, GP ... Display panel, L ₁ , L ₂ ... Signal transmission line, M ₁ , M ₂ , M ₀₁ , M ₀₂
… Modulation circuit, MEM ₁ , MEM ₂ ,, MEMO ₁ , MEMO ₂ … Memory, R ₁ , R ₂ ,, R
₀₁ , R ₀₂ ... Code receiving circuit, S ₁ , S ₂ , S ₀₁ , S ₀₂ ... Code transmitting circuit, TW ... Typewriter. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] 1. A remote monitoring device having clocks in a master station and a slave station, wherein the master station periodically transmits a time setting signal and a setting command signal to the slave station, and the slave station When the time setting signal is stored in the memory and the clock at the slave station is corrected by the setting command signal, and the time of the time setting signal transmitted from the master station next time or the time at the slave station is corrected, the time setting signal is changed. The time synchronization method in the remote monitoring device, characterized in that the operation of performing correction based on the difference between the time and the time of the clock in the slave station immediately before correction is performed until the difference disappears. 2. Upon receiving the setting command signal, the slave station transmits the clock in the slave station immediately before correction to the master station, and the master station receives the time from the slave station and the time of the time setting signal. The time of the time setting signal to be transmitted to the slave station next time is corrected so that the difference becomes smaller, and the master station and the slave station may exchange the time setting signal and the time information until the difference disappears. A time synchronization method in a remote monitoring device according to claim 1. 3. The difference between the time of the time setting signal and the time of the clock of the slave station immediately before correction is accumulated many times on the slave station side, and the slave station calculates and receives a correction value based on the accumulated data and receives it. The time synchronization method in the remote monitoring device according to claim 1, wherein the time of the time setting signal is corrected by the correction value.