JPS62278602A - Knowledge decentralization control method for plant - Google Patents

Abstract

PURPOSE:To attain the easy expansion/reduction of the function as well as the easy maintenance with high reliability and a fast processing speed for the titled control method, by controlling the plant control knowledge after dividing it into a knowledge group of the entire plant and the other one proper to each plant equipment. CONSTITUTION:The plant equipments E1 and E2 are controlled by controllers C1 and C2 respectively. The operating states of these equipments are observed by measuring devices M1 and M2 and given to a controller. The output of the controller is sent to the operating A1 and A2 and these devices control the plant equipment. An operator console OP is connected to a controller C0 and the states of the switches, etc., operated by an operator are sent to the controller Co. While the output of the controller C0 is sent to the operator by an indicator, etc.

Description

[Detailed Description of the Invention]: 3. Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention provides a method for controlling a plurality of equipment in a large-scale plant by using a plurality of computers connected through communication lines. This invention relates to a knowledge-distributed control method for a plant that is controlled through an inference function.

(Prior Art) Many systems have been put into practical use that connect multiple computers to a local area network (hereinafter referred to as LAN) to control large plants such as power plants and steel mills.

In general, the knowledge used when controlling a plant can be broadly classified into the following four types.

■ Knowledge of the characteristics and operation of plant equipment.

■ Knowledge of operating procedures between plant equipment.

■ Knowledge of rules, standards, etc.

(a) Knowledge of external phenomena that affect the plant.

Plant equipment is distributed throughout the plant premises, and each control device is often installed near the equipment. Therefore, it is recommended to install a LAN within the premises and to transmit signals and information between the control devices via the LAN. It will be done.

However, with the conventional production rule set, it is not possible to divide it into separate sets and perform inference in parallel for each separate set. Problems have arisen in that the speed-up, function expansion, and ease of maintenance cannot be fully satisfied.

(Problems to be Solved by the Invention) The present invention stores experiential knowledge for controlling plant start-up, operation, shutdown, etc. in a computer, performs inference for each device in parallel based on this knowledge, The purpose of this study is to provide a knowledge distributed control method for plants that efficiently controls plant equipment.

[Structure of the invention]

(Means and operations for solving the problems) In the control method of the present invention, each control device has a calculation device, and this calculation device is composed of a storage device and a normal calculation device or an inference calculation device.

The storage device stores knowledge and data related to the control device, and inference is performed by executing the inference software of the computing device.

Reasoning on one control device is performed in units of software modules called objects installed in each control device, and objects receive messages transmitted by objects in other control devices transmitted via LAN, and perform self-control. Calculations or inferences corresponding to this message are performed using the data and knowledge stored in the device, and the results are used to generate control outputs to plant equipment, rewrite self-memory data, and send messages to objects in other control devices. Send.

The operations of calculation, inference, and control performed by the objects described above are executed in cooperation with each other through message communication, thereby starting, operating, and stopping the plant.

The following objects are the basis of this method.
and message communication
ng) will be explained.

Objects are expressed in a special language called an object-oriented language as follows.

The following expressions are OKB L (object) developed by Toshiba.
oriented knotzledge base
d language), but other languages with similar formats may also be used.

C: object <object name> (: 5t
ate (state variable name and its initial value) (: 5u
per <superior object declaration>) (:
receive (<message>)・・・・・・・・・
・)] In the above description, the description in the part surrounded by square brackets is rewritten according to the purpose.1 For example, an object named "rloi counter" is described as follows.

(: object decimal counter (: 5tat
e (C: =O] ) (: 5upper
counter )(:receiva(:up)
CC: =(add I C)))(: recs
iva (: count?) C)] Here, 8tata is the memory value of this object,
It is indicated by the count value C of a decimal counter, and its initial value is 0.

5uper is a counter, and for example, a binary counter, an 84 counter, or the like is used in addition to an IO counter.

Receiva describes the symbol strings (messages) that this object can receive and the processing to be performed after receiving them. This decimal counter is a symbol string (: up) (
message) is given, performs the operation of adding 1 to C and assigning the result to C again, and (: coun
T? ) is given, it returns C to the message source.

In this example, the messages defined by the object and available for receipt are sent via the LAN from objects residing in other control devices. Although not included in the decimal counter description above, objects can send messages.

Next, in order to describe the description for specifying the transmission destination and transmission method, we will first describe a message transmission/reception method between objects, which is an important point of the present invention.

The message sending/receiving method according to the present invention can be classified into the following types.

(a) One-to-one communication immediate return type (no sending message type) Response waiting type immediate return mail reception type (b) One-to-many communication (multicast) immediate return type (
(No sending type) Waiting for a reply type Waiting for all replies type 1 waiting for reply type Immediate return mail receiving type (c) Broadcast communication (broadcast) Immediate return type (no sending type) Immediate return mail receiving type Object A is another object T When exchanging messages with someone, if T is one, it is one-to-one communication, and if T is a specific number of T, , T, ... TN, it is one-to-one communication.
Point-to-many communication, where T is an unspecified number of people, is broadcast communication.

FIG. 1 shows the basic system configuration of the present invention.

That is, N plant equipment EL to EN from 1 to N.
, control devices WC, -C, and operating devices A1 - AH, respectively.

Control device! ! 01 to CN can be realized by a computer system as shown in FIG. In this computer system,
The main memory [21 is connected to the arithmetic control unit W via the memory bus 22]
123. Auxiliary storage controller @24. An input/output controller M25 and a direct memory access l[26 are coupled.

In FIG. 1, control devices C1 to C are each connected to a LAN.
It is connected to the communication line 1 via the control devices ifL to LN. Each of the LAN controllers-1 to LN2 is indicated by 29 in the figure, and is connected to the memory bus 22 via a direct memory access device W126.

In FIG. 1, output data from the control devices Wcs to CN are passed to operating devices A to AN, respectively, and the operating devices operate plant equipment E2 to En based on this data. The operating device is indicated by 28 in FIG. 2 and is connected to the memory bus 22 via the input/output controller 25.

Inside the main storage device 21, there is a special area for temporarily storing messages, and this area is an input message buffer (hereinafter referred to as the IN buffer) and an output message buffer (hereinafter referred to as the OUT buffer). It is divided into two parts.

The IN buffer and OUT buffer are shown in FIG. 3A.

As shown in B, this is a storage area in which a necessary number of words capable of storing fixed-length character strings are arranged consecutively, and these words have consecutive addresses.

One word of the IN buffer stores one of the incoming messages. Also, one message to be sent is stored in one word of the OUT buffer.

A flag (1-bit information) is attached to each word to indicate whether the word contains a message to be used or not (is empty).

The direct memory access device 26 sends the message to LA.
N control system! ! When the message is received from 29, it is immediately stored in a vacant word of the IN buffer, and the received signal is returned to the LAN control device that sent the message.

Objects are written in the aforementioned object-oriented language and stored in the main memory 21, and this program is an arithmetic and control unit! ! 23.

In this program, only the message defined in the dotted line in the sentence containing the word receive, i.e. (:receive...), will be called this receive.
This is a message that can be accepted by the receive statement.

Management of the IN buffer is performed by the operating system in the control device 13. The operating system retrieves the message that entered the IN buffer the earliest and stores it in the receive file containing that message.
Execute the statement.

If the rectAve statement is executed first according to the flow of the program and the message defined by this statement is not stored in the IN buffer, execution of the receive statement is temporarily suspended until the message is retrieved. Ru.

One control! 13, it is possible to run a program that describes a plurality of objects. Since all the messages that an object wants to receive are defined in advance by the receive statement, the messages needed by each control device can be scheduled in advance. Therefore, among the messages stored in the IN buffer, it is possible to select which messages are needed and which are not. Therefore, each time a new message is stored in the IN buffer, a screening program is activated to determine whether it is necessary or not, and if it is unnecessary, it vacates the word in which it is stored.

The OUT buffer stores a transmission sentence, which will be described later, and the OUT buffer
One word in the T-buffer is assigned to one object. When Q objects are executed concurrently within one control device, the OUT buffer is composed of Q words.

When a sent message is executed, the entire sent message is stored in the OUT buffer corresponding to the object containing the sent message. Simultaneously with the execution of the transmission sentence, a signal is sent to the direct memory access device Wt26, and the direct memory access device 26 takes out the transmission sentence from the OUT buffer, sends it to the LAN control device 29, and empties the corresponding word in the OUT buffer.

The LAN control device 29 analyzes the contents of the transmitted message and transmits the message to the necessary destination. For communications other than broadcast communications, the received signals are received from all destinations, and after receiving them, the arithmetic and control unit 23 is notified of the reception.

Execution of the transmission statement in the arithmetic and control unit 23 is completed upon notification of receipt of the received signal. That is, execution of the program is temporarily suspended until acknowledgment of the received signal is received.

The transmission text is defined as follows for each type of message transmission/reception method. T.A.

B and C are destination object names, M is a message, and X is a mailbox name.

(1) Immediate return type transmission statement format: For one-to-one communication (T <-M) For broadcast communication (() <-M1 Procedure: 4th
As shown in the figure.

That is, a description regarding object A is executed in a certain control device 13. In this description of A, there is a transmission sentence (T
<-M), and when this transmission statement is executed, this transmission statement is sent to the LAN control device 29 using the method described above. L
AN control system! ! 29 deciphered T and M from this transmission,
Transmission is performed using the name of the LAN control device where 1' exists as the destination and M as the transmission data.

After receiving the transmission, the LAN control device 29 detects the presence or absence of a transmission error, and then stores the message M in the main memory bag Vi2 via the direct memory access device 26 of the control device using the method described above.
1 into the IN buffer, and immediately after that, the source L
Returns the received signal to the AN control device.

The sender LAN control device that received the received signal transmits this signal to the control device 6. The control device waits for the completion of execution of the transmitted message [T<-M] until it receives this received signal. , upon acceptance, the execution ends and the program execution resumes.

(2) Format of response-waiting transmission: For one-to-one communication: (T<-M) For one-to-many communication: For example, when sending message M to A, B, and C, wait for all responses. The type is ((A, B, C) (-M) 1 response waiting type is (IA, B, CI<-M) Procedure: Figure 5 shows.

In other words, when a sent message (T < -M) is executed, even after M is received by the control device where T exists and the execution of the sent message is completed, the following processing is performed. , execution of the source object is in a wait state.

In the description of M, there are variables to which the answer value should be assigned (for example, K x
)It is included. The description of object T includes a statement to receive M, and when this is executed, the contents of M are decoded and processing corresponding to the contents indicated in M is performed. Assign the answer value of the processing result to X, and re
Execution of the receive statement ends.

When the execution of the receive statement including Kyoin is completed, the arithmetic control unit notifies the LAN control unit. When the description of M includes a variable starting with Toin as shown above, the LAN control device that received M remembers the name of the sending control device,
Upon completion of execution of the receive statement, the value assigned to X is transmitted to the sender. The LAN control device that is the sender knows that when it sends M, X will be returned, so after receiving X, it allocates it to X in the main storage device 21 through the direct memory access control device 26. The transmitted value is stored in the new word, and the arithmetic and control unit 23 is instructed to resume execution.

In FIG. 5, the procedure from ■ to ■ and ◎ is the same as the corresponding part in FIG. 4, and the explanation thereof will be omitted.

In the case of one-to-many communication, the sent text is ((A, B, C) <-M)
In this case, when this send statement is executed, the CA is actually
<-M], (B<-M), (CAM) are executed sequentially,
Each takes the steps shown in FIG. At point ◎, execution of the next program is resumed when all responses from A, B, and C are received.

If the transmission statement is of the one-reply wait type, execution of the next program is resumed when any one response is received at point ◎.

(3) Format of immediate return mail reception type transmission: % expression %)) Procedure: The communication procedure when this transmission is executed is exactly the same as the immediate return type procedure (FIG. 4). In this case, a request is made to T for a reply corresponding to M, and the reply is transmitted and stored in the word named y on the main memory 21 of the control device @13 that is the sender. is demanding that.

However, in this case, the sending control device does not wait for the reply to y to arrive; after the execution of the sent statement is finished, it continues to execute the next program, checks whether y has a value at an appropriate time, and then enters the If it's there, use it, and if it's not, check again at the next convenient time.

When this type of send statement is executed, the sender's LAN
The control device 12 stores the fact that data will be returned from T, and the direct memory access device [26 stores the address of the word named y and the data to be stored in T.
It will be remembered that the item will be returned to you.

When the value to be assigned to y is sent in the same manner as ◎, ◎, and ■ in Fig. 5, the direct memory access device stores the value in the word corresponding to y on the main memory 21, and Flag indicating that the value is unused (1-bit storage unit)
Set to 1. Only one flag is provided on the main storage device 21 corresponding to y.

The value sent to y is called a mail.
Mail is a string of symbols. A program can easily use mail by reading the contents of the above flag indicating whether mail has arrived. After using mail, reset this flag to 0.

(Example) The series of processes spanning plant start-up, operation, and shutdown are as follows:
It is composed of many subprocesses, and one subprocess is separated from the next by an abstract concept called a state.

For example, the startup process of a certain thermal power plant includes the following partial processes.

Startup process: Preparation for startup Boiler ignition drum Steam boost Pressure increase after fuel system switching (coal firing) Boost turbine ventilation Turbine - Next rotation increase (up to 800 rpm) Turbine secondary rotation increase (3000# II) System synchronization input Primary load increase ( (up to 25% of rating) Secondary load increase (up to 50% of rating) Tertiary load increase (up to 100% of rating) An abstract concept called state exists at the connection point of these partial processes.5 For example, startup preparation and boiler ignition In between, there is a state called "ready to start," which is widely recognized by operators.

In order to briefly explain the embodiment, it is assumed that there are only two plant devices in the configuration shown in FIG. The configuration of the present invention in this case is as shown in FIG.

In FIG. 6, plant equipment E tEz is controlled by controllers C□ and C2, respectively. The operating state of the plant equipment is measured by the measuring device M1. It is measured by M2 and transmitted to the controller. The output from the controller is the controller A,, A,
The operator controls the plant equipment based on this information.

Operator console ○P is connected to controller C,
Controller C0 controls the status of switches etc. operated by the operator.
The output from the controller C0 is transmitted to the operator through a display or the like.

A plant in a certain state S undergoes a partial process and returns to state S1.
FIG. 7 shows how the system of FIG. 6 operates in the case of a transition to +1.

FIG. 7 shows the flow of processing in the controller [C, , C1, C, where the plant is in state SL,
After passing through the partial process, the plant becomes in the state S1+1 at (3).

When C0 receives input from the operator that affects the current state, it first determines the next state SL+1 using data (i.e., state measurement values of plant equipment) for determining which state to proceed to. . The data necessary for this determination is collected from each control device, and this collection can be performed by the above-mentioned message sending/receiving type all-reply waiting type one-to-many communication.

Based on the received data, C, determines the next state,
To make this decision, reasoning using empirical rules can be performed and the results can be used. Controller C0
In the configuration shown in FIG. 2, the operating device 28 in FIG. 2 is replaced by an operator console oP. Rules used for inference execution are stored in the auxiliary memory bag [27, and are transferred to the main memory 21 as needed to be used for inference. Addition, modification, and deletion of rules are performed by operator operations from the operator console OP.

Control device! Once c o has determined the next state Si÷1, this is transmitted to the control device 1ctt Cx by broadcast communication or one-to-many communication. After receiving this, C□ and C2 measure the state of the plant equipment, perform necessary calculations or inferences, and determine the output. Rules necessary for inference are stored in the main memory of each control device. This output is sent to each plant equipment via the operating device 28.

Each controller partially determines whether the next state of the plant S i+1 has been reached by controlling the plant equipment (only for the part related to that plant equipment), and the partial information that S L+1 has been reached is determined by each controller. is sent to the controller Ca by instant return type one-to-one communication or the like.

The controller C0 makes a comprehensive judgment based on the partial information sent from each controller to set the plant to the next state S L+1.
It is determined that the state has been reached, and this is replaced with the current state. The following procedure is a repeat of the above.

Note that the communication port m11 in FIG. 1 can be formed into a ring shape, and various types of local area networks can be used.

〔Effect of the invention〕

As explained above, according to the present invention, knowledge regarding plant control is managed separately into a knowledge set for the entire plant and a knowledge set specific to each plant device, and inferences based on this are executed in parallel. , high reliability, faster processing, easier expansion/reduction of functions, easier maintenance, etc. can be achieved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the general system configuration of the present invention, Figure 2 is a diagram showing the general system configuration of the present invention.
The figure shows the internal configuration of one control device in FIG. 1, FIGS. The figure shows the general procedure for sending and receiving messages in the immediate return type 121 communication, and Figure 5 shows the response waiting type 1:
6 is a diagram showing the system configuration of an embodiment consisting of three $11 devices, and FIG. 7 is a diagram showing the basics of message transmission and reception in the embodiment of FIG. 6. FIG. L, 29... LAN control device C913... Control device A, 28... Operator E... Plant equipment 1
1... Communication line 21... Main storage device 22.
...Memory bus 23...Arithmetic control unit 24...
・Auxiliary memory control bag! ! 25... Input/output control device 26.
... Direct memory access control device 27 ... Auxiliary storage device Agent Patent attorney Yoshiaki Inomata (and one other person) Figure 1 (IN bar 777) (OLJ
Ding bar/77) (A) (B) Fig. 3 Migo box = I word 1
Sill: fl (II Fig. 4 Fig. 5 39 Fig. 6 0C1C2 Fig. 7

Claims (1)

[Claims] A first control device that stores knowledge related to the operation of the entire plant and a plurality of second control devices that store knowledge related to the control of each of a plurality of plant devices are connected via a communication line, and the first control device stores knowledge related to the operation of the entire plant. determines the current state of the plant, deduces the next state to which it should move, and sends this as a message to the second control device, which receives the transmitted message and controls the respective plant equipment. It is characterized by controlling the plant to move to the next state and transmitting the control state to the first control device from time to time, so that the first control device determines whether the plant state has reached the next state. A knowledge-distributed control method for plants.