JPH0450798B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a remote monitoring device that monitors a monitoring target such as an electric power system, and in particular accurately recognizes state change times and grasps the state change order. The present invention relates to a transmission signal processing method suitable for.

[Conventional technology]

In recent years, computer systems that collect and monitor numerical information such as the status of equipment and power consumption in geographically scattered power systems have been deploying highly functional slave stations at electrical stations such as substations. The system configuration is such that information is transmitted from the station to the central computer system, and switches are opened and closed through slave stations based on commands from the central computer. An example of the overall configuration of this system is shown in FIG.

When an accident occurs in the power system, the protection system is designed to ascertain the accident situation as much as possible and recover as quickly as possible, and to minimize the scale of the accident. An important issue is to accurately understand the order of operation.
This type of report creation has become one of the essential functions of power system monitoring systems. For this purpose, the monitoring system has a configuration in which the slave stations add the operation times of protection relays, etc. to status information (operation data) and send it to the central computer _P.
Misrecognition of the operating time is avoided by the transmission time of data from ~C _o to the central computer (hereinafter referred to as master station) P. For this purpose, each slave station C ₁ to _{C o} has a clock, but in power systems that are closely connected by power transmission lines, protection relay operations in the event of an accident span multiple electrical stations, and multiple slave stations involved in an accident is reported to the master station P. In such a situation, in order to accurately know the operating order of relays, etc., it is necessary to make the times of C ₁ to _{C o} of all slave stations the same. The need to accurately know this sequence of operations is important in identifying the location of an accident and investigating the cause of the accident. Conventionally, the following two measures have been considered and implemented regarding this point.

(1) A method in which the master station P corrects the absolute time transmitted from the slave stations C ₁ to _Co. This method uses the master station P
The data transmission delay is corrected using a constant bias value. This correction value is calculated from the data transmission speed and data length of the communication line, but in order to ensure accuracy, the following a) to c) must be taken into consideration.

a) Rise time of the modem carrier signal;
b) Processing time of the communication device; c) Processing time of the slave station/master station. (2) A method of making the absolute time itself of the slave station accurate and making it consistent throughout the device. An example of this method is Brown Bovely Review 9/10-
84 (Brown Boveri Rev. 9/10-84) is known. In this method, slave station C
be equipped with a highly accurate standard time device, or
As shown in FIG. 3, the slave station C corrects the time transmitted from the master station P by providing a minute signal pulse generator or the like. This method requires as many time devices as there are slave stations C, making the entire system expensive. To explain Fig. 3 in detail, the slave station C prepares a minute pulse signal of the time, and uses the minute pulse signal to correct the transmission time etc. with respect to the absolute time transmitted from the master station P. C temporarily stores the absolute time of the master station P in a temporary area, and synchronizes the internal clock of the slave station C with the next minute pulse signal. For example, when data indicating 13:00:0 is transmitted from the master station P, the slave station C sets its internal clock to 13:01:0 when the minute pulse is input immediately after reception.

[Problem that the invention seeks to solve]

In the method (1) above, points a) and b) are not uniform among each device, and it is impossible to know the degree of variation in advance. Furthermore, since these times vary depending on environmental conditions such as temperature, there is a problem in that it is not possible to accurately determine when to make corrections.

On the other hand, in the method (2) above, equipping each slave station with a highly accurate time device requires an enormous amount of equipment cost. In addition, the accuracy of knowing the time depends on how accurate minute pulse signal generators are provided in all slave stations, so if this is required, Problems that are difficult to solve remain.

Therefore, the present invention provides a transmission system that can accurately grasp the order of state changes without providing precise time devices in all slave stations, and without being affected by differences in communication equipment or fluctuations in environmental conditions. The purpose is to provide a signal processing method.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention uses the standard time in the master station and slave stations as relative time (elapsed time) that takes into account the communication time between the master station and slave stations, rather than the absolute time. The main feature is that the reference time is determined and processed by calculation at the master station.

That is, the first invention of the present application has a master station P, and a plurality of slave stations C ₁ to C _o installed corresponding to each monitoring target, each having a time counter, and connected to the master station via a transmission line. In a remote monitoring device that monitors the status of a monitored target by transmitting status information of the monitored target from each slave station to a master station, the master station instructs the slave station to reset its time counter. A signal TMS is transmitted at a predetermined period, and after resetting its own time counter using this reset command signal, a response signal R-TMS is returned from the slave station to the master station, and the response is started from the transmission time _T1 of the reset command signal. Measure the elapsed time T ₂ - _{T 1} until the signal reception time T ₂ , and the time when 1/2 of this elapsed time, that is, (T ₂ - _{T 1} )/2 has elapsed.
The present invention is characterized in that _TR is estimated as the reset execution time of the time counter, and the state change time of the monitored object is recognized based on this estimated reset time _TR .

Further, the second invention of the present application includes a master station, and a plurality of slave stations installed corresponding to monitoring targets, each having a time counter, and connected to the master station via a transmission line, In a remote monitoring device that monitors the status of a monitored target by transmitting status information of the target from each slave station to a master station, the master station transmits a command signal to the slave stations to reset their time counters; After resetting its own time counter using the reset command signal, the slave station returns a response signal to the master station, measures the elapsed time from the transmission time of the reset command signal to the reception time of the response signal, and calculates the elapsed time. The time at which 1/2 of the time has elapsed is estimated to be the reset execution time of the time counter, the state change time of the monitored object is recognized based on this estimated reset time, and the recognized state change time is set as the parent. This system is characterized in that it is corrected to an absolute time within the station, and the state change information of the processes is aggregated and output in the order of the corrected absolute time.

To summarize the above, in the present invention, a time counter conventionally provided in a slave station is reset from a master station at high intervals, and the elapsed time (relative time) after resetting the time counter is utilized.
Additionally, a command is issued from the master station to the slave station to reset the time counter (hereinafter referred to as reset command TMS).
In response, the slave station receives the reset command TMS, executes the reset command TMS, and then replies to the master station that the execution has ended (hereinafter referred to as response signal R-TMS).
) is transmitted with the same data length as the reset command TMS.

The transmission time _T1 of the reset command TMS is memorized in the master station, and based on the time _T2 when the slave station receives the response signal R-TMS, the time at which the time counter in the slave station is reset is calculated using the following formula. Estimated by

Reset time = T ₁ + (T ₂ − _{T 1} )12 Then, the master station sorts (classifies or rearranges) the state change information transmitted from each slave station based on the above reset time, thereby sorting the state change information. Output in the order in which state changes occur. The output format may be a screen display using a CRT display or a hard copy to a printer.

[Effect]

According to the present invention having the above configuration, the master station issues a time counter reset command TMS to the slave station.
is transmitted after an elapsed time determined by the system configuration of the monitoring device. Next, this reset command TMS
In response to this, after the reset command is executed, the response signal R-TMS is transmitted from the slave station to the master station after approximately the same elapsed time as described above.

The breakdown of the elapsed time (hereinafter referred to as transmission time) from the sending time of the reset command TMS to the reset command execution time is generally an integrated value of the following times. That is, firstly, the time required for the master station to send the reset command TMS to the communication device (master station processing time), and the time required for the second communication device to raise the modem carrier signal and transmit the reset command TMS. time (communication device processing time), third, the time required for the reset command TMS to be transmitted via the communication line (data transmission time), and fourth, the time required for the slave station to receive the reset command TMS and reset the time counter. This is the time required to do so (slave station processing time).

On the other hand, the elapsed time from the execution time of the reset command TMS at the slave station to the reception time at which the response signal R-TMS is received by the master station (hereinafter referred to as reply time).
can be substantially the same as the above transmission time if the response signal R-TMS uses the same data length as the reset command TMS. This is because the configurations of the transmission path and the reception path are the same despite the difference in transmission direction, and the difference in time required for the first, second, fourth communication processing, etc. is negligible.

From the above, assuming that the sending time and receiving time are substantially the same, the execution time of the reset command for the time counter located at an intermediate point in time is set to 1/2 the sum of the sending time and receiving time. It can be estimated as the time. That is, it is expressed as T ₁ +(T ₂ −T ₁ )/2.

In this way, by setting the estimated reset time as the standard time and recognizing the order of occurrence of status change information (succeeding relationship) based on this estimated reset time, a common absolute time can be used between the master station and the slave stations. This enables accurate sorting of status information.

According to the processing method of the present invention, regardless of the transmission/reception method (point-to-point or multi-drop method) between the master station and the slave station, variations and differences in the models and performance of communication devices, modems, etc., differences in transmission speed, and seasons. The time of the slave station can be appropriately determined without depending on changes in the required time due to temperature changes. This makes it possible to accurately determine the time of state changes that occur within a short period of time between each slave station, and enables the master station to accurately grasp the order in which state changes occur in the entire power system. . Since state change data is simultaneously transmitted to the master station from the numbered child stations, the order in which the data is received does not correspond to the order in which the state changes occur. The master station can provide the user with accurate relay operation order results by rearranging each state change data in the order of occurrence time.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

Overall Configuration of Remote Monitoring Device FIG. 1 shows the overall configuration of a remote monitoring device according to the present invention. For each target to be monitored (not shown) such as a switch in the power system, slave stations C ₁ , C ₂ ,...
..., _Co are installed, and each slave station C ₁ , C ₂ , ..., _Co is equipped with a time counter (not shown). Each slave station C ₁ , C ₂ , . . . , _Co is connected to the master station P via an appropriate transmission line. Main station P
has a state change record file F, which allows each state change information to be sorted chronologically in the order of occurrence along with time data.
The recorded information is output and displayed on a CRT or printer PRNT.

Estimation of Reset Execution Time of Slave Station Time Counter FIG. 4 shows a calculation method for estimating the reset execution time of the slave station time counter in the signal processing method of the present invention.

The communication program of the master station P has a reset command.
After raising the self-priority level just before issuing TMS,
Capture and store the absolute time _T1 . Reset command
TMS is transmitted to slave stations C ₁ , C ₂ , ..., _Co , and
C ₁ , C ₂ , . . . , _Co sends a response signal R-TMS to the master station P after resetting the time counter. When the master station P receives the response signal R-TMS, the master station P
Retake T ₂ and calculate ΔT=(T ₂ −T ₁ )12.

The master station P sets T ₁ +ΔT as the counter reset time. When the slave stations C ₁ , C ₂ , ..., C _o report a change in the status of the switch, etc., the master station P changes the slave stations C ₁ ,
The state change time is determined as follows from the counter values simultaneously reported by C ₂ , ..., _Co.

Change time=(counter value)×R+T ₁ Here, R is the time for the counter value 1.

The above process is performed every time at a cycle less than half the time at which the time counter overflows. According to this embodiment, not only can the time of state change occurring in _the slave stations C _{1 ,} C _{2 ,} . ..., C _o
Since it is executed individually for each child station, it is possible to accurately calculate the time of a state change that occurs between multiple slave stations. In addition, since the standard time is determined using the elapsed time, which is the relative time of transmission and reception when resetting the count value of the time counter in short cycles, the internal clocks in slave stations C ₁ , C ₂ , ..., _Co It has the advantage that errors are not accumulated and there is no need to have an internal clock with particularly high accuracy.

Method for Calculating Status Change Time Next, an example of a method for calculating the true/false status change time when a status change occurs in the monitored object will be explained based on the reset time estimated by the above method.

FIG. 5 shows an example of a method for calculating the state change time.
According to this example, the master station P determines the generation time of the reset command TMS and the reception time _T2 of the reset command TMS reply.
The reset time of the time counter in the slave station is calculated and stored as described above. Reset command for slave station
Immediately after receiving the TMS, reset the count value of the local time counter. According to this example, the time counter updates the count value (+1) every 2 msec.
However, if the count value exceeds, the maximum count value is maintained. When a state change is reported from the actual plant, the slave stations C ₁ , C ₂ , ..., C _o import the state change data and at the same time update the count value (n).
is added to report the occurrence of a state change to the master station P. The master station P requests the slave stations C ₁ , C ₂ , ..., Co to transmit state change data, and after receiving the _data , it recognizes the state change point and adds a count value (n)
Then, add 2 msec x n to the reset time of the time counter to calculate the state change time.

In order to prevent the count value from exceeding, the master station P transmits a reset command TMS at a cycle approximately half of the counter overtime, thereby preventing the counter from exceeding.

Processing when an error occurs on the line at the time of reply from a slave station Next, a case will be described in which an error occurs on the line when the reset command TMS is sent.

FIG. 6 shows the completion of transmission of the reset command TMS from the master station P to the slave stations C ₁ , C ₂ , ..., _Co , and the transmission of the reset command TMS from the master station P to the slave stations C 1 , C ₂ , .
C ₂ , . . . , _Co resets the time counter, but the response signal R-TMS cannot be received on the master station P side due to a line abnormality. The master station P detected a timeout because the response signal R-TMS, which is the reply data to the reset command TMS, was not received, and sent the latest signal to the master station _P to the slave stations C ₁ , C ₂ , ..., Co. A request is sent to retransmit the data in the transmission buffer, which is the content. The master station P determines whether a line abnormality has occurred between the master station and the slave station (TMS) or between the slave station and the master station (R-TMS) based on the transmission buffer data. If there is an abnormality while transmitting the response signal R-TMS, the slave station C ₁ ,
It can be determined that C ₂ , . . . , _Co has processed the reset command TMS and reset the time counter. In this case, the correction value ΔT calculated when the previous reset command TMS was sent is used, and (TMS transmission time) + ΔT is set as the counter reset time. There is no difference between the previous ΔT and the ΔT to be calculated this time because changes in temperature and equipment are not considered.

Processing in the case of a line abnormality during transmission from the master station Next, a processing method in the case of a line abnormality during transmission of a reset command from the master station will be described with reference to FIG.

If the contents of the transmission buffer are reset command
When the TMS is not returned (that is, R-TMS), the slave stations C ₁ , C ₂ , ..., _Co send the reset command TMS.
Since this means that the master station P has not received the reset command TMS, the master station P re-executes the reset command TMS and
Calculate counter reset time for TMS command.

Execution of retransmission request in case of line abnormality is carried out by slave stations C ₁ , C ₂ ,
..., repeated a certain number of times until a reply is received from C _o ,
If no reply is received within the specified number of times, the master station P determines that the slave station or line is permanently out of order and stops communication.

In this way, the master station calculates the exact time of occurrence of the state change data, adds the time together with detailed data such as the name of the state change point, and stores the data in the state change record file. The continuously captured state change data is compared with the time in the record file, and the record file is sorted in chronological order and stored. In this manner, state change data is continuously processed and stored in a recording file. Since the state change due to an accident in one power system ends within a certain period of time, for example, if there is no new state change 1 minute after the last state change time, the state change due to the accident is considered to have ended. without consideration,
Print or display the status change record to the user on a form or screen.

This memory is passed to the person in charge of the power system's protection system and used for designing the protection system, such as re-adjusting relay operation settings.

As described above, since the time within the slave station can be accurately controlled without being affected by the transmission rate, variations in equipment, or environmental conditions, the following effects can be achieved.

(1) It is possible to know the time of state change with an accuracy of about 5 milliseconds without having a standard clock equipment in the slave station.
Simultaneous state changes between slave stations can also be detected with an accuracy of approximately ±5 msec.

(2) The counter is updated every minute, so 1/500
A clock with moderate accuracy is sufficient. Additionally, the status change records output by this device have a significant effect on confirmation and redesign of power system protection systems.

〔Effect of the invention〕

As described above, according to the present invention, the order in which the status of the monitored object changes can be accurately determined without providing a precise clock device in all slave stations and without being affected by differences in communication equipment or fluctuations in environmental conditions. can be grasped.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a remote monitoring system according to the present invention, FIG. 2 is an explanatory diagram showing a conventional example of a general monitoring system, and FIG. 3 is an explanatory diagram showing a conventional time setting method. FIG. 4 is a time chart showing the method of calculating the time counter reset time in the transmission signal processing method according to the present invention, and FIG. 5 is a time chart showing the method of calculating the state change time.
FIG. 6 is a time chart showing a processing method in the case of a line abnormality during a response from a slave station, and FIG. 7 is a time chart showing a processing method in the case of a line abnormality during transmission from a master station. P...Master station, _C1 to C _o ...Slave station, _T1 ...Reset command transmission time, _T2 ...Response signal reception time, T _R
...Reset time, ΔT...Elapsed time, TMS...
...Reset command, R-TMS...Response signal.

Claims (1)

[Scope of Claims] 1. A master station, a plurality of slave stations installed corresponding to each monitoring target, each having a time counter, and connected to the master station via a transmission line, In a transmission signal processing method in a remote monitoring device that monitors the status of a monitored object by transmitting status information from each slave station to a master station, the master station sends a command signal to the slave station to reset its time counter. After resetting its own time counter using this reset command signal, the slave station returns a response signal to the master station, and measures the elapsed time from the time when the reset command signal is transmitted to the time when the response signal is received. , the time at which 1/2 of this elapsed time has elapsed is estimated as the reset execution time of the time counter, and the time at which the state of the monitored object changes is recognized based on this estimated reset time. Transmission signal processing method in equipment. 2. In the method described in claim 1,
1. A transmission signal processing method in a remote monitoring device, characterized in that a reset command signal is transmitted at a shorter cycle than a transmission/reception cycle of status change information between a master station and a slave station. 3. A master station, and a plurality of slave stations installed corresponding to monitoring targets, each having a time counter, and connected to the master station via a transmission line, and transmitting status information of the monitoring targets to each slave station. In a transmission signal processing method in a remote monitoring device that monitors the state of a monitored object by transmitting a signal from the master station to a master station, the master station transmits a command signal to reset the time counter to the slave station, and the reset command signal After resetting its own time counter by The time when the time counter 2 has elapsed is estimated to be the reset execution time of the time counter, the state change time of the monitored object is recognized based on this estimated reset time, and the recognized state change time is transmitted within the master station. A transmission signal processing method in a remote monitoring device, characterized in that the process is corrected to an absolute time, and the state change information of the process is aggregated and output in the corrected absolute time order. 4. In the method described in claim 2,
1. A transmission signal processing method in a remote monitoring device, characterized in that a reset command signal is periodically transmitted at a cycle shorter than a transmission/reception cycle of status change information between a master station and a slave station.