JPS5853250A - Decentralized control system - Google Patents

Abstract

PURPOSE:To increase the reliability of a decentralized control system, by forming a transmission line so as to facilitate the acquisition of the latest control information that is necessary for a subcontroller to monitor the state of its adjacent subcontrollers and to perform the bumpless swithching. CONSTITUTION:A fault of a subcontroller SC1 is detected by a self-diagnosis or the monitor of the state given by an adjacent subcontroller SC2. Thus switches W1A, W1B and W1C are switched to a bypass mode. In the bypass mode, the secondary loop transmission line of the SC2 has a route of 20-21-11-(adjacent controller of SC1)-14-15-16-17-24-25-26-27-28. Then P11-P13 which are so far put under the control of the SC1 and the SC1 are put under the control of the SC2. As a result, the SC2 can be connected with no bump with the input/output processs of the P11-P13 and by means of the control information which is obtained before the fault of the SC1 occurs.

Description

[Detailed Description of the Invention] The present invention relates to a control system for a plant, particularly for plans that require high reliability and safety, such as nuclear couplants.
K relates to a preferred distributed control system.

An example of a conventional distributed system is shown in FIG. The host controller HC has main transmission lines 1, 2゜3.4, 5
．． 6 and 7 to perform system-wide management tasks. Subcontroller SCI.

SC2 is the input/output conversion circuit pH~P13゜P2
1 to P23'i to the operating device V such as the detector S1 valve.
Performs input/output processing for. WIA here.

W2A is a switch whose function is shown in FIG. Normally, the switch W connects the terminals a and d, and the terminals C'l and C'l, as shown in FIG. 2A. When an abnormality occurs in the related sub-controller, the same figure (
As shown in b), a and c are connected, and b and dl are connected, respectively. Since this mode is used for signal bypass, it is hereinafter referred to as bypass mode.

FIG. 1 shows the system configuration when the sub-controller SCI fails. If SCI fails, WIA
switches to bypass mode as shown. As a result, the signal flow in the main loop is changed to main transmission lines 1, 4, 5, .
6 and 7, and the failed controller 5cii is bypassed, so the failure of SC1 does not affect the entire system. However, pH ~ P13 and S, V under SC1 control
stops functioning completely. If the SCI and SC2 are performing input/output processing for completely separate targets, it is meaningful that the operations of the SC2 and the Vs and Ss under its control can continue. However, when SC1 and SC2 share input/output processing for one large target,
Even if it is possible to continue the operation of SC2 and S under its control, it is often pointless.

For this reason, recently, even when the above sub-controller fails,
The operation of S, ■, which was under its control, can be substantially continued,
The method shown in FIG. 3 has been attempted to minimize system downtime. In this method, SC1, pH, PI3. and P.I.
3 as sub-loop transmission lines 10.11, 12, 13, 14.1
5 and 16, SC2 and P21. P22. P23 is connected by sub-loop transmission lines 20, 21, 22, 23, 24, 25 and 26. For example, if SC1 fails, switches WIA, WI B, and WI C go into bypass mode, SC1 is disconnected from the sub-loop transmission line, and the sub-loop transmission line under SC1 is connected to the sub-loop transmission line of SC2. and sub-loop transmission line 20°21.22,23,24
, 12, 13, 14° 15. Make loops of 11, 25 and 26. As a result, Pi1. PI3. and PI3 can continue operating under the control of SC2. However, in this method, there is no transmission path between subcontrollers other than the main transmission path used for communication with the HC. A drawback is that it is very difficult to constantly monitor the status of the SCI and to obtain the latest control information for the pan press switching basin.

The object of the present invention is to enable the sub-controller to
An object of the present invention is to provide a transmission line reconfiguration type distributed control system that facilitates monitoring of controller status and obtaining the latest control information necessary for bumpless switching.

A feature of the present invention is that by connecting an adjacent controller to the sub-loop transmission path of each controller, each controller can command its own input/output conversion circuit, and in the same way, the adjacent controller 'f: can be seen at a glance and can obtain the latest control information. The reason lies in the fact that we have made it possible.

An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure shows the system configuration of this embodiment. Symbols are 1st to 3rd
It is similar to the figure. This figure shows a case where the sub-controller is normal. SC2 is 20-21-22-23-24-2
P21~ by the sub loop transmission line of 5-26-27-28
At the same time as managing P23'e, the status of S01 is monitored and control information is obtained.

In this sub-loop transmission path of SC2, SC2 is the master station, P2
1. P22. P23. SCI and each are in the relationship of slave stations.

Similarly, SC1 uses the subloop transmission line 1O-11-(adjacent controller)-14-15-16-17-18.
In addition to managing P11 to P13, it also monitors the status of adjacent controllers connected to its own subloop and obtains control information.

In this way, in the present invention, each sub-controller can periodically monitor the status and obtain control information of the adjacent controller to be backed up, regardless of communication with the host controller through the main transmission path, for example, at the control cycle. It is possible.

Methods of status monitoring include a method of simply monitoring responses, and a method of performing simple calculations and monitoring the results. Further, the control information includes integral values of PID control, input/output data, and the like.

FIG. 5 shows the system reconfiguration when an abnormality occurs in SC1. Abnormalities in SC1 are determined by (f) SCI self-diagnosis,'
(ii) Discovered by status monitoring by the adjacent controller SC2. When an abnormality is discovered, switch WIA,
WI B, WIC switches to bypass mode. As switching means, it has a watchdog timer of SC1, an instruction from SC1, and a switching instruction from adjacent controller SC2. The control line for switching the switch is omitted in FIG. 4 and this figure.

When the switch is in bypass mode, the subloop transmission path of SC2 is 2 (1-21-11-(SCI adjacent controller)-14-15-16-17-24-25-2
The pH was 6-27-28 and was under the control of SC1.
The neighboring controllers of P13 and SCI are brought under the control of SC2.

As a result, input/output processing from pH to P13 can be continued bumplessly using the control information obtained before the occurrence of the SC2 and SC1 abnormalities.

However, the SC2 stores a control program in advance for backing up the adjacent SCI.

Furthermore, unless SC2 has sufficient performance margin from the beginning, the performance of SC2 generally decreases when it takes over the management of pH to P13. Specifically, the performance degradation includes a decrease in processing speed. However, even if processing performance decreases,
The effect of being able to continue operating the system as a whole is far greater.

In this embodiment, only two sub-controllers are shown in the figure, but any number of sub-controllers may be used.

Further, the host controller may be omitted, and the main transmission path is not limited to the loop method. Although the transmission line may be an electric wire such as a twisted pair wire, an optical fiber cable is convenient from the point of view of insulation between each sub-controller. In this case, an optical switch is used as the switch.

According to the present invention, a sub-controller can regularly monitor the status of adjacent sub-controllers and obtain the latest control information regardless of the communication status of the main transmission line, so transmission line reconfiguration that allows bumpless switching is possible. This has the effect of configuring a type of distributed control system.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration and operation of a conventional distributed control system, Fig. 2 is an explanatory diagram of the operation of a switch, Fig. 3 is a configuration diagram of a distributed control system that has been recently attempted, and Fig. 4 is the invention of the present invention. FIG. 5 is a system configuration diagram of one embodiment, and FIG. 5 is an explanatory diagram of reconfiguration operation of one embodiment. HC...Host controller, SC1, SC2...
Sub-controller, W, WIA, WI B, WIC.

Claims (1)

[Claims] 1. In a distributed control system consisting of a plurality of controllers connected to a transmission line, the transmission line is the main transmission line, and separate from this, an individual sub-loop transmission line is provided for each controller, and the sub-loop transmission line is connected to the main transmission line. connects a detector, an operating device, and a controller adjacent to the controller, and in normal times, each controller performs input/output processing for the detector and the operating device, and monitors the adjacent controller and provides the latest control information. However, when the adjacent controller is abnormal, the abnormal adjacent controller is disconnected from the main transmission path and the secondary loop transmission path of the abnormal adjacent controller, and the abnormal controller is connected to its own secondary loop transmission path. 1. A distributed control system comprising a switching means for disconnecting the sub-loop transmission line of the abnormally adjacent controller and connecting all the sub-loop transmission lines of the abnormally adjacent controller.