JPS646579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a remote monitoring and control system that defines a communication procedure between a terminal device and a central device.

2. Description of the Related Art A power distribution line-carrying remote monitoring system is a typical remote monitoring and control system that monitors terminal devices located far away. In this system, as shown in FIG. 1, signals are transmitted between a relay device 1 provided for each block and a central device 2 using a communication line 3. Further, signals between the terminal device 4 in the same block and the relay device in that block are transmitted by transmitting a high frequency carrier signal through the power distribution line 5. Each relay device 1
is provided to convert signals between the communication line 3 and the power distribution line 5.

Conventionally, distribution line-based remote monitoring systems have adopted a remote monitoring and control method called the polling method, in which a central device takes full control.
FIG. 2 is for explaining the system operation of the remote monitoring and control method. In this system, the central device first sends out a paging signal 6 ₁ for the first terminal device to all terminal devices. Since the calling signal includes address information indicating the terminal, only the first terminal device can receive this calling signal 6 ₁ . When the first terminal device receives the calling signal 6 ₁ , it sends back the monitoring signal 7 ₁ to the central device. The monitoring signal is a signal that notifies the presence or absence of a change in status, such as a distribution line accident, for example. The central device monitors signal 7 ₁
If it receives correctly, it sends out a paging signal 6 ₂ to the second terminal device. Thereafter, the central device sequentially performs the monitoring operation from the first terminal device to the Nth terminal device (N is an arbitrary number) in the same manner. Note that in this figure, the relay device only plays the role of a signal converter.

In the conventional remote monitoring and control method, the central device sequentially calls terminal devices that do not need to report at that time.
The disadvantage is that the total monitoring time increases in proportion to the increase in the number of terminal devices. In other words, as the number of terminal devices increases, it becomes difficult to collect information on distribution line accidents, information on the occurrence of breakdowns in power distribution equipment, changes in protective switches due to accidents, etc. in a short time, and it becomes difficult to maintain the system. This led to undesirable results.

For this reason, consideration is being given to adopting a remote monitoring and control method that combines a method called a contention method, in which a terminal device that detects a state change is activated without a paging signal and immediately sends a request signal to the central device. . However, when attempting to incorporate both the polling method and the contention method into a power distribution line-carrying remote monitoring and control system, the following problems arose.

(1) When about 10 terminal devices are connected to one distribution line, several terminal devices may simultaneously detect changes in status such as short circuits and ground faults in the event of a distribution line fault. In such a case, communication is impossible even if the central unit is in a standby state. Third
The figure is for explaining an example of such a case. For example, assume that the first terminal device and the second terminal device simultaneously detect a change in state. These terminals in this case simultaneously transmit activation signals 8 ₁ , 8 ₂ . This causes signal interference in the central device, making it unable to receive signals.

(2) On the other hand, if a terminal device starts up while the central device is monitoring all the terminal devices in sequence, communication becomes similarly impossible even if only a single terminal device starts up. FIG. 4 is for explaining an example of such a case. For example, assume that the central device transmits a paging signal 6 ₁ to a first terminal device, and the first terminal device starts transmitting a monitoring signal 7 ₁ in response thereto. At this time, when the second terminal device detects a state change and transmits the activation signal 8 ₂ , the monitoring signal 7 ₁ and the activation signal 8 ₂ interfere with each other. In this case, if the central device transmits the paging signal 6 ₁ again, it will be possible to correctly receive the monitoring signal 7 ₁ sent from the first terminal device. However, in this case the activation signal 8 ₂ sent from the second terminal device
will be ignored. In this case, the central device detects a change in state for the first time when it transmits a normal paging signal 6 ₂ to the second terminal device and receives a corresponding monitoring signal 7 ₂ .

Due to these problems, conventional remote monitoring and control systems have adopted only the polling method and have not been able to use the contention method in combination.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a remote monitoring control method that can be used in conjunction with a contention method to collect changes in status in a short time.

In the present invention, a predetermined activation acceptance time is set in the system, and activation signals are transmitted at different time intervals until each terminal device receives activation. Thereby, the above-mentioned purpose is achieved by ensuring that the activation is accepted at the activation acceptance time.

The present invention will be explained in detail with reference to Examples below.

FIG. 5 is a diagram for explaining a remote monitoring and control method in a distribution line carrying type remote monitoring and control system. In this system, 13 terminal devices are grouped into one block. That is, the first block integrates the first to 13th terminal devices, and the second block integrates the 14th to 26th terminal devices.
Terminal devices are integrated. The same applies to the terminal devices after the 27th terminal device not shown.

In this system, (1) each terminal device is equipped with a function (terminal activation function) that immediately sends an activation signal to the central device when a state change is detected. In addition, (2) the central device has a function of transmitting an activation stop signal that instructs each terminal device to stop transmitting the activation signal. Further related to this, (3) each terminal device is provided with a function of repeatedly transmitting the activation signal at predetermined intervals until it receives the activation stop signal. The transmission interval of this activation signal is set to be different between terminal devices belonging to the same distribution line system. (4) After the central device performs a polling-based monitoring operation on all terminal devices in one block, it waits for a predetermined period of time during which the monitoring operation is suspended, and then starts monitoring the next block. It is set. This period is shown as activation acceptance time T in the figure.

At the start of remote monitoring control, the central device first starts a polling-based monitoring operation for each terminal device in the first block. That is, the central device sequentially sends out paging signals 6 ₁ to 6 ₁₃ to each terminal device, and monitor signals 7 ₁ to 7 ₁₃ from these terminal devices.
will be received.

By the way, at time _t1 when the first block is being monitored and controlled in this way, the second and third blocks are
Assume that the terminal device detects a change in state. These terminal devices immediately transmit the first activation signals 8 ₂ -1, _{8 3} -1 at this time t ₁ . These activation signals 8 ₂ -1, _{8 3} -1 are sent to the central unit, but the central unit cannot receive them. That is, the central device receives these activation signals 8 ₂ -1, _{8 3}
-1 is ignored and monitoring control is executed by polling.

Now, as described above, the second and third terminal devices each have a function of repeatedly transmitting the activation signal at different transmission intervals. Therefore, the second and third terminal devices transmit the second activation signals 8 ₂ -2, 8 ₃ -2 at predetermined times t ₂ and t ₃ (however, t ₂ ≠ t ₃ ) after time t ₁ , respectively. do. As shown in the figure, if these activation signals 8 ₂ -2 and _{8 3} -2 are similarly ignored, the second and third terminal devices will be activated at subsequent times t ₄ and t ₅ (however, t ₄ ≠t ₅ ), the third activation signals 8 ₂ -3, _{8 3} -3 are transmitted. In this way, the activation signals 8 ₂ -3 and _{8 3} -3 transmitted at the activation acceptance time T are both correctly received by the central device. When the central device receives the activation signal 8 ₂ -3, it sends out a activation stop signal 9 ₂ to stop the second terminal device from being activated thereafter. Similarly, when the central device receives the activation signal 8 ₃ -3, it sends out an activation stop signal 9 ₃ to stop the third terminal device from starting from now on. In this way, the activation of the second and third terminal devices is quickly detected without waiting for the end of the monitoring control of the terminal devices after the second block.

It should be noted that from the above explanation regarding the control operation, it is understood that the activation interval of each terminal device should be kept within a predetermined limit range. That is, first of all, (1) the activation interval must be set shorter than the activation acceptance time T. This is because if it is set longer than the startup acceptance time, there will be cases where the startup will not be accepted. Furthermore, (2) it is not preferable to set the startup interval to be extremely short compared to the time required for polling one block. This is because the shorter the activation interval, the more the number of terminals whose reception becomes abnormal due to the activation signal increases, resulting in a decrease in the efficiency of monitoring and control. Of course, not only the startup interval but also the number of terminal devices to be integrated into one block and the startup acceptance time T should change depending on various conditions such as the communication speed and data length of the applied system, and will vary depending on each system. It is to be determined.

FIG. 6 shows the configuration of a terminal device used in this system. A signal arriving at the terminal device from the central device via the power distribution line 5 is extracted by the high voltage coupling circuit 11 and converted into a digital signal by the demodulation circuit 12. This digital signal is sampled by the receiving circuit 13 and supplied to the determining circuit 14. The determination circuit 14 receives the address of its own terminal device from the address setting unit 15, and verifies whether the received signal is related to its own terminal device (address verification).
I do. At the same time, an error check such as a parity check is performed on the digital signal. As a result, when a signal related to its own terminal device is correctly received, it is determined and a signal corresponding to the content of the signal is output to the reception control circuit 16.

When the reception control circuit 16 receives a control signal related to the control of the device from the determination circuit 14, it controls the external contact according to the content of the signal. Further, when a calling signal is received, a signal for transmitting a monitoring signal is outputted to the transmission control circuit 17. When the transmission control circuit 17 receives this signal,
The transmission data editing circuit 18 is controlled to create a monitoring signal including the address of its own terminal device supplied from the address setting section 15 and the external state supplied from the state change detection circuit 19. This monitoring signal is sent from the transmission data editing circuit 18 to the modulation circuit 21 and modulated into an FS (Frequency Shift) signal. This modulated monitoring signal is amplified by the amplifier 22 and then passed through the high voltage coupling circuit 11 to the distribution line 5.
and sent to the central unit.

By the way, when the external state changes due to an accident on a power distribution line, the state change detection circuit 19 detects this,
The content of the state change is supplied to the transmission data editing circuit 18. Further, the state change detection circuit 19 sends a signal to the activation control circuit 23 when a change occurs in the external state and on the condition that no external contact control is performed. When the activation control circuit 23 receives this signal, it sends a control signal to the transmission control circuit 17 at predetermined activation intervals to control the activation operation.
In this example, the startup interval settings for each terminal device are
This is done using address information supplied from the address setting section 15. If this method is adopted, it is possible to automatically manage the activation interval by managing the addresses, and it is possible to eliminate the complexity of management.

Now, each time a control signal is sent from the activation control circuit 23, the transmission control circuit 17 causes the transmission data editing circuit 18 to create an activation signal. This activation signal is a signal that includes an address and an external state,
This signal is the same in content as the monitoring signal described above.
The created activation signal is sent to the central device in the same way as the monitoring signal.

When the activation signal sent out in this manner is received by the central device at activation acceptance time T (FIG. 5), the central device sends out an activation stop signal. When the terminal device that sent the activation signal correctly receives this activation stop signal, it outputs a stop signal from the reception control circuit 16 to the activation control circuit 23. This resets the activation control circuit 23 and stops sending out the activation signal.

According to the present invention, since both the polling method and the contention method are compatible, the time from detecting a state change on the terminal device side to confirming it on the central device side can be significantly shortened. As a result of improving the responsiveness of system control, the reliability of the system can be significantly improved.

In addition, although the control method for a distribution line-carried remote monitoring and control system was explained in the embodiment, the control method of the present invention can be similarly applied to various telemeters, telecontrol systems, and data transmission systems that require similar system reliability. Of course it can be applied.

[Brief explanation of the drawing]

Figure 1 is a system configuration diagram of a distribution line-carrying remote monitoring and control system, Figure 2 is an explanatory diagram of system operation to explain the conventionally adopted remote monitoring and control method, and Figures 3 and 4 are conventional proposals. This is to explain the remote monitoring control method that uses both the polling method and the contention method. Figure 3 is an explanatory diagram of system operation when multiple terminal devices are activated in response to one state change. , FIG. 4 is an explanatory diagram of the system operation when the terminal device starts up while the central device performs monitoring control using the polling method, and FIGS. 5 and 6 show the remote monitoring and control system in one embodiment of the present invention. FIG. 5 is an explanatory diagram of the system operation, and FIG. 6 is a block diagram showing the configuration of the terminal device. 2...Central device, 4...Terminal device, 8...Start signal,
23...Start control circuit.

Claims (1)

[Claims] 1 A large number of terminal devices connected to one central unit are grouped into two or more blocks, and each block is monitored and controlled using a sequential polling method. A start signal reception time for receiving start signals from each terminal device is set between the monitoring control method using the polling method and the polling method monitoring control of the next block, and the start signal reception time for receiving the start signal from each terminal device is set between the monitoring control method using the polling method of the next block. The activation signal is repeatedly sent out at different time intervals with the starting point being the starting point, and among these activation signals, the activation signal sent at the activation reception time described above is received by the central device side, and the terminal that sent this activation signal is A remote monitoring and control system characterized in that a central device sends back an activation stop signal to the device to stop further transmission of the activation signal.