JPS6333995A - Time synchronizing method in remote supervisory equipment - Google Patents

Abstract

PURPOSE:To synchronize the clock of a master station and the clock of a slave station automatically gradually by correcting a set time signal based on the difference of the time between the set time signal added with a transmission delay time sent from the master station and the clock of the slave station. CONSTITUTION:The time t0 (date, hour, minute, second, milli-second) to be set periodically from the master station 0 and a set command signal are sent to each slave station. In this case, the time t0 to be set is the addition of the time of the master clock, the delay time from the master station 0 to the slave station and the time from the send of the set time to the sending of the set command signal. After the time of slave clocks CL1, CL2 just before rewrite is sent to the master station 0, the time is rewritten at the slave station. The master station comapres the time 0 sent to the slave station and to be set with the times t1, t2 just before the rewrite and sent from the slave station. The difference is the difference of the time between the slave clocks CL1, CL2 and the real slave clock considered by the master station 0 and the time t0' to be set next is corrected to decrease the difference and then the error is controlled to be close to zero gradually.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 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 remote monitoring device disclosed in, for example, Japanese Patent Application Laid-Open No. 56-116199. In FIG. station,
1 and 2 are slave stations, GP is a display panel that shows the status of each slave station, and a CD
is a control console for issuing control commands to each slave station 1 and 2, TW
is a typewriter for recording operations and data, CPo is an arithmetic processing circuit, DOl is an output circuit, DIo is an input circuit, TC is a typewriter control circuit, and CL is a master clock circuit.

TR is a code transmitting/receiving circuit, and MD is a modulation/demodulation circuit.

In slave stations 1 and 2, symbols CP, cp2 are arithmetic processing circuits, MDi and MD are modulation/demodulation circuits, and TR.

TR, is a code transmitting/receiving circuit, DIl, DI2 are input circuits,
Dol and Do are output circuits, and CL, CL2 are slave clock circuits. Furthermore, Ll and L are signal transmission paths connecting the master station 0 and the slave stations 1 and 2, respectively.

Next, a method of synchronizing the clocks of the master station O and the slave stations 1 and 2 will be explained. During this time synchronization, the master station 0
The arithmetic processing circuit CP0 transmits the time to (for example, 0:00:00:00:00 am) to be set. Each slave station 1, 2
Then, this is received and the arithmetic processing circuit CP1. CP2 stores the time t0 to be set and waits for the next setting command.

The master station O issues a setting command signal a preset time τ milliseconds ago, which is considered to correspond to the transmission delay time to each slave station 1, 2, and when this signal reaches the slave stations 1, 2, the arithmetic processing circuit CP , CP, sets each child clock CL□, CL2 to time t. Set to .

[Problems to be Solved by the Invention] However, since the time synchronization method in such a conventional remote monitoring device is configured as described above, the expected transmission delay time τ milliseconds is a fixed value; If the signal transmission path changes and the transmission delay time changes,
An error occurs in the clocks of the master station and slave station. In recent years, in order to increase the reliability of signal transmission lines, two or more signal transmission lines, such as regular lines and detour lines, have been established, and if one fails, the system automatically switches to the other.

Furthermore, a switching device may be provided in the middle, but in this case, the transmission delay time may change each time.

On the other hand, as power systems become more highly electrified, the operating time of protective relays and the like is becoming shorter, and errors due to the difference in expected transmission delay times cannot be ignored in accident analysis.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a time synchronization method for a remote monitoring device that can automatically synchronize the clocks of a master station and a slave station. do.

[Means for Solving the Problems] A time synchronization method in a remote monitoring device according to the present invention provides a time synchronization method for a remote monitoring device in which a master station and a slave station each have a clock. A command signal is transmitted to the slave station to correct the clock of the slave station, and time information of the clock in the slave station immediately before correction is transmitted to the master station, and the time setting is transmitted from the master station. By modifying the value signal, the time of each clock of the above-mentioned master station and slave station can be synchronized.

[Function] In the time synchronization method for a remote monitoring device according to the present invention, the set time signal is corrected based on the difference between the set time signal that takes into account the transmission delay time sent from the master station and the time of the clock of the slave station. As a result, the clocks of the master station and the clocks of the slave stations are gradually automatically synchronized.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
The figure is a system block diagram showing a remote monitoring device for implementing a time synchronization method as an embodiment of the present invention. In this figure, 0 is a master station, 1 and 2 are slave stations, GP
is a display panel that shows the status of each slave station, CD is a control console for issuing control commands to each slave station 1 and 2, TW is a typewriter for recording operations and data, CPo is an arithmetic processing circuit, DO
o is the output circuit, DI. is the input circuit, TC is the typewriter control circuit, CL is the master clock circuit, MEM is the memory,
D.1. Do2 is a demodulation circuit, M, 1. M, 2 is a modulation circuit, Rott R, is a code receiving circuit, S Oll S
O2 is a code transmission circuit.

Further, in slave stations 1 and 2, symbols CP□ and cp2 are arithmetic processing circuits, DI0. Di2 is an input circuit, DO□.

DO2 is an output circuit, and CL□ and CL are slave clock circuits. MEM, MEM2 is a memory, DL and D2 are demodulation circuits, M and M2 are modulation circuits, and S 9S2 is a code transmission circuit. Furthermore, Ll and L are the master station O and slave station 1, respectively.
, 2.

Next, the operation will be explained. At slave station 1 or 2,
Operation signals of protective relays and status signals of circuit breakers, etc. are input through the input circuit DI or DI2, and the time of occurrence is read from the slave clock circuit CL or CL2 of each slave station 1, 2, and the time and occurrence event are calculated. It is also transmitted to the master station O. Therefore, if the slave clocks of each slave station are not synchronized, master station 0 may not be able to arrange the information sent from the slave stations in the order of occurrence, which may lead to erroneous judgment by the operator. .

Therefore, the time to (
(2:02:02, milliseconds) and a setting command signal to each slave station. At this time, set the time. is the time of the master clock, the transmission delay time from the master station O to the slave station, and the time from transmitting the time to be set until transmitting the setting command signal.

On the slave station side, as shown in FIG. 2, the time t to be set.

The memory MEM1. Store in MEM2 and wait for setting command signal. When the setting command signal is received, the slave clock CL1. The time of CL, is rewritten to to, but the time of the slave clock CL, CL2 immediately before being rewritten is transmitted to the master station O, and then rewritten.

The master station O compares the time t0 to be set transmitted to the slave station with the time t□+tz immediately before rewriting transmitted from the slave station. This difference is the child clock CL□ considered by the master station 0,
This is the difference between the time of CL and the actual time of the slave clock, and the next time t should be set so that this difference becomes smaller. ′ is corrected.

Note that if you try to correct it in one go, there is a risk of hunting, so you may want to correct the average error over several thousand times in the past, or correct it in increments of a fraction of the error (in other words, reduce the gain). This method controls the error so that it gradually approaches zero.

In the above embodiment, an example was shown in which the time information immediately before rewriting is sent to the master station to calculate the correction, but as shown in FIG. 3, the slave station has a memory MEM○.

MEMO, the correction value calculation circuit AC stores the difference between the time to be set sent from the master station and the time of the child clock immediately before rewriting for several dozen times in the past, and calculates the correction value based on these data. , , AC2, and this correction value may be added to the information sent from the master station to set the time.

In addition, as a method of calculating the correction value, a method of averaging the past several thousand errors has been described, but it goes without saying that necessary transfer functions may be used in order to obtain a stable system.

[Effects of the Invention] As described above, according to the present invention, corrections for transmission delay time, etc. are automatically corrected, so even if the signal transmission route is changed or the delay time in the middle of the transmission path changes. This has the effect of automatically synchronizing the clocks of the master station and the clocks of the slave stations.

[Brief explanation of drawings]

Figures 1 to 3 show a device for implementing the time synchronization method in a remote monitoring device as an embodiment of the present invention. Figure 1 is a system block diagram thereof, and Figure 2 is a slave station side thereof. FIG. 3 is a block diagram showing another example to explain the functions on the slave station side, and FIG. 4 shows a time synchronization method in a conventional remote monitoring device. FIG. 2 is a system block diagram showing an apparatus for implementing the method. In the figure, 0-master station, 1.2-slave station, AC,. AC, - correction value calculation circuit, CD - control console, CL, - master clock circuit, CL engineering, CL, - child clock circuit, cpo. cp engineering, cp, - arithmetic processing circuit, D z t D z
tDOL tDo2--demodulation circuit, D1. , DI2.
DI, - input circuit, Do. , Dol, Do, -output circuit, GP-display panel, Ll, L2-signal transmission line, M□+
Mg2 M,. M,2-Modulation circuit,MEM,,MEM,,MEMOl. M E M O, --Memory, R1, R,, R,,, R
, 2-... code receiving circuit, S x t S 2 t S
o t t S o 2-code transmission circuit, TW-・-
typewriter. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] (I) In a remote monitoring device in which a master station and a slave station each have a clock, a time setting value signal and a setting command signal are transmitted from the master station to the slave station, and the slave station By correcting the clock, transmitting the time information of the clock in the slave station immediately before the correction to the master station, and correcting the time setting value signal transmitted from the master station, the master station and slave station can A time synchronization method in a remote monitoring device, characterized by synchronizing the time of each clock with a station. (2) The time information of the clock of the slave station immediately before correction is stored in the slave station, and the time setting value signal transmitted from the master station is corrected using this accumulated data. A time synchronization method in a remote monitoring device according to item 1.