For general acquaintance with the system, a block diagram is provided (Fig. 6.2). Structural scheme - this is a diagram that defines the main functional parts of the product, their purpose and relationships.

Structure - this is a set of parts of an automated system into which it can be divided according to a certain attribute, as well as ways to transfer the impact between them. In general, any system can be represented by the following structures:

• ? constructive - when each part of the system is an independent constructive whole;
• ? functional - when each part of the system is designed to perform a specific function (full information about the functional structure, indicating the control loops, is given on the automation diagram);

Rice. 6.2.

? algorithmic - when each part of the system is designed to perform a certain algorithm for converting the input value, which is part of the functioning algorithm.

It should be noted that block diagrams may not be given for simple automation objects.

The requirements for these schemes are established by RTM 252.40 “Automated process control systems. Block diagrams management and control". According to this document, constructive block diagrams contain: technological subdivisions of the automation object; points

control and management, including those not included in the project being developed, but having a connection with the system being designed; technical staff and services that provide operational management and normal functioning of the technological object; the main functions and technical means that ensure their implementation at each control and management point; relationships between parts of the automation object.

The elements of the block diagram are shown as rectangles. Separate functional services and officials may be shown as a circle. Inside the rectangles, the structure of this section is revealed. The functions of an automated process control system are indicated by symbols, the decoding of which is given in the table above the main inscription according to the width of the inscription. The relationship between the elements of the structural diagram is depicted by solid lines, merging and branching - by lines with a break. The thickness of the lines is as follows: conditional images - 0.5 mm, communication lines - 1 mm, the rest - 0.2 ... 0.3 mm. The sizes of elements of block diagrams are not regulated and are chosen at discretion.

The example (Fig. 6.2) shows a fragment of the execution constructive scheme management and control of the water treatment plant. In the lower part, the technological divisions of the automation object are disclosed; in the rectangles of the middle part - the main functions and technical means of local units control points; in the upper part - the functions and technical means of the station centralized control point. Since the diagram occupies several sheets, the transitions of the communication lines to subsequent sheets are indicated and a broken rectangle is shown, revealing the structure of the automation object.

On the communication lines between the individual elements of the control system, the direction of the transmitted information or control actions can be indicated; if necessary, communication lines can be marked with letters of the type of communication, for example: K - control, C - signaling, remote control, AR - automatic control, DS - dispatching communication, PGS - industrial telephone (loud-speaking) communication, etc. P.

Is the control scheme in acquisition mode. At the same time, it is connected to the technological process in the manner chosen by the process engineer.

The connection is carried out by means of interfacing with the object (USO). Measured values ​​are converted to digital form. These quantities are converted into units according to the corresponding formulas. For example, to calculate the temperature measured by a thermocouple, the formula T = A * U2 + B * U + C can be used, where U is the voltage at the output of the thermocouple; A, B and C are coefficients. The calculation results are recorded by output devices for subsequent study of the technological process under various conditions of its passage. Based on this, it is possible to build or refine a mathematical model of the controlled process.

This mode does not have a direct impact on the technological process. Here I found a cautious approach to the implementation of management methods in process control systems. However, this scheme is used as one of the mandatory control sub-schemes in other more complex process control schemes.

In this scheme, the process control system works at the pace of the technological process. The control loop is open, i.e. the outputs of the process control system are not connected with the bodies that control the technological processes. Control actions are carried out operator-technologist receiving recommendations from the computer.

All necessary control actions are calculated by the computer in accordance with the process model, the calculation results are provided to the operator in hard copy(or in the form of messages on the display). The operator controls the process by changing the settings.

Regulators are the means to maintain optimal process control. The operator performs the role of a follower and manager, whose efforts the process control system continuously and accurately directs to optimize the performance of the technological process.
The main disadvantage of this control scheme is the presence of a person in the control circuit. With a large number of input and output variables, such a control scheme cannot be used due to the limited psychophysical capabilities of a person. However, this type of management also has advantages. It satisfies a cautious approach to new management methods.

Advisor mode provides a good opportunity to test new models technological processes. The process control system can monitor the occurrence of emergencies, so that the operator has the opportunity to pay more attention to the operation of the installations, while the process control system can monitor a greater number of emergency situations than the operator.

Supervisory management.

In this scheme, the process control system is used in a closed loop, i.e. the settings for the regulators are set directly by the system.

1. Management of an automated transport and warehouse. In such a system, the computer issues the addresses of the rack cells, and the system of local automation of stacker cranes works out their movement in accordance with these addresses.
2. Management of melting furnaces. The computer generates setpoint values ​​for controlling the operating modes of electric furnaces, and local automation, by computer commands, controls the transformer switches.
3. Machine tools with numerical control.

Direct digital control.

In mode direct digital control(NCU) the signals used to actuate the control bodies come from the process control system, and the regulators are generally excluded from the control system. Regulators are analog calculators that solve a single equation in real time, such as this:

where y may indicate the position of the valve; k0, k1, k2, k3 - settings, thanks to which the controller can be configured to work in different modes; X - the difference between the measured value and the setpoint. If X is not =0, then moving the control body is required to bring the process to the specified mode.

If the regulator uses the first two terms of the equation for its work, then it is called. If the first three terms are used, then the regulator is proportional-integral, and if are all terms of the equation, then the controller is proportional-integral-derivative.

The NCU concept allows you to replace regulators with a setpoint. Real impacts are calculated, which are transmitted directly to the control bodies in the form of appropriate signals. The NCU scheme is shown in the figure:

Designations introduced:
MA - managed object
D is a sensor.

The settings are entered into the automated control system by the operator or a computer that performs calculations to optimize the process. The operator must be able to change the settings, control some of the selected variables, change the ranges of the allowable change of the measured variables, change the settings, and must also have access to the control program. One of the main advantages of the NCU mode is the ability to change control algorithms by making changes to the control program. The main disadvantage of the direct digital control scheme is the ability of the system in the event of a computer failure.

ACS is an abbreviation that stands for Automated Control Systems. The answer to the question, what is ACS, can be formulated as follows: it is a set of technical systems and processes, organizational complexes and scientific methods that allow to ensure optimal control a complex technical process or object, as well as a team of people who have one common goal.

In contact with

Structural diagram of ACS

In the structure of any automated control system, the following components can be distinguished:

1. The main part - includes mathematical and Information Support and technical part.
2. Functional part - implies specific managerial functions and a number of related programs.

Systems can be elementary or large and complex.

It is customary to distinguish between two structural varieties of such systems - an automated process control system (APCS) and a system organizational management(ASOU).

The differences among these systems lie in the characteristics of the object that the system will manage. Process control systems are built to control complex technical objects, mechanisms, devices, machines. ASOU are designed to control the functioning of teams of people. According to the use of automated control systems, the methods of transmitting information will also differ - these can be documents or various physical signals.

There is also an abbreviation for SAU - system automatic control. Its peculiarity lies in the fact that it can act for some time without human intervention. Such systems are used to manage small hotel facilities.

Application and main functions of ACS

ACS are widely used in various fields industrial production. The main functions of the systems are as follows:

Basic principles of ACS

For the first time principles of action automated systems management, the procedure for their development and creation were formulated by V.M. Glushkov.

Information base of automated control system

The information base of the automated control system can be called the entire set of information placed on machine media and necessary for the normal functioning of the system.

As a rule, all information base It is conditionally subdivided into three sectors - general, derivative and operational.

Technical characteristics of the automated control system

Under the technical base of the automated control system, it is customary to understand all the technical means that are used to collect, accumulate and process information, as well as to display and transmit it. This also includes the executive nodes of the system that affect the control object.

The main technical elements and equipment of the automated control system are electronic computers that ensure the accumulation and processing of all data circulating within the system. This technique allows you to simulate production processes and build proposals for management.

For the construction and management of automated control systems, two types of electronic computers are used - accounting and regulatory and information and settlement.

Information and computing equipment is at the highest hierarchical level in management system. Their task is to resolve all issues related to the centralized management of the facility. Such mechanisms are characterized by high speed, the presence of a system of interrupts, variable word length, syllabic processing of input data.

The lower level of the control system, as a rule, is given to accounting and regulatory mechanisms and equipment. These mechanisms are usually placed directly on the sites or in production shops. Their task is to collect input data from control objects and the primary processing of this information, followed by its transfer to the information and settlement department and the receipt of planned directive information. In addition, the accounting and regulatory part of the equipment is engaged in local calculations and generates control actions on control objects in case of deviations from the calculated functions. This part of the control system has a well-developed connection with large quantity sources of information and control devices.

Mechanical means of collecting and displaying information

If the system provides for the collection and processing of information with the participation of a person, it includes various registrars that allow you to receive initial data directly from workplaces. This also includes all kinds of temperature sensors, timers, meters of the number of manufactured parts and other similar equipment. Automatic deflection fixators are also mounted in manufacturing process, which register and transmit to the system information about the absence of materials, tools, Vehicle to send manufactured products, as well as irregularities in the operation of machines. Such equipment is installed not only in industrial premises, but also in warehouses for storing raw materials and finished products.

Data display means include all devices that allow displaying information in the most accessible form for a person. This includes all kinds of monitors, scoreboards and screens, printers, terminals, indicators, etc. These devices are connected directly to the central processor of a computer and can provide information either regulated or sporadically - at the request of the operator or in the event of an emergency.

The technical base of automated control systems also includes various types of office equipment, instrumentation and accounting devices that ensure the normal functioning of the main technical units.

The main element of the system are control units (BU) electrolyzer. Each unit controls two baths, except for the CU. installed at the ends of the cases, each of which controls one bathroom. Accordingly, in each building for 98 baths (buildings 1 and 2 of the electrolysis shop), 50 control units are installed. All blocks are united in a single network of the electrolysis building. The top-level computer (workstation of the operator of the building) and the current/voltage controller of the series (CTNS) are included in the same network. The workstations of the building operators are connected via the Ethernet network to the workstations of the technologist.

TROLL control unit

TROLL control units are manufactured at the SPU plant (St. Petersburg). When designing the unit and choosing components, many typical failures for Russia were taken into account. For example, manual override buttons and motor starters have no moving parts, preventing them from sticking to moisture or dirt. Implemented, of course, and multi-level software protection against various hardware failures.

Ease and convenience of maintenance are ensured by the modular design on the connectors, which makes it possible to quickly replace individual units.

BU TROLL are installed in the electrolysis building next to the electrolyzers. The dimensions of the block are 1600x600x400 mm (height/width/depth).

In the lower part of the block there are power modules for controlling the anode frame drive motors, as well as terminal blocks to which the equipment of the electrolyzer is connected and power is supplied to the control unit. On the door of the lower part there are circuit breakers for supplying motors.

At the top of the block is an Octagon MicroPC controller along with Grayhill optical isolation modules. All inputs and outputs of the control unit are galvanically isolated. In the upper part, there are temperature control modules for the control unit, including heaters and fans that provide a constant positive temperature inside the unit.

On the door of the upper part there is an indication and control panel of the unit, consisting of two LED displays for indicating the parameters of the operation of the electrolyzers, combined with membrane keypads for controlling the electrolyzers. In the middle is a membrane keyboard for selecting the display mode. The panel, controlled by a separate microcontroller, allows:

display up to 64 different operation parameters of the electrolyzers and the control unit;

set the setpoint values ​​for the control parameters of electrolyzers;

switch between manual, automatic and special regimes management;

control in manual mode anode motors and automatic alumina supply systems.

It should be noted that all manual control signals pass through the MicroPC controller. The reliability of the channel (keyboard controller M1sgorS optocoupler modules equipment) is not inferior to relay circuits usually used for this, while the controller “knows” about manual actions, records them and takes them into account during further automatic control, and can also limit or prohibit them under certain conditions, correcting gross errors of the staff.

Above the panel there are lamps indicating the 3-phase voltage of the motors and alarms.

The controller of the control unit includes: processor board 5025A (processor - i386SX-25 MW; RAM- 1 MB; non-volatile memory - 512 KB; flash drive - 512 KB; operating system- ROM-DOS 6.22), two 5648 I/O boards and an Arcnet 5560 network board. The controller receives signals from 2 analog and 25 digital inputs and controls 22 digital outputs (all inputs/outputs are optically isolated 1.5-4 kV). up to 14 analog inputs, 34 digital inputs and 6 digital outputs can be set. It should be noted that the characteristics of the controller are an order of magnitude superior to those of other systems, where a typical controller pmce "1 1 speed of a 16-bit processor with a clock frequency

has the speed of a 16-bit processor with a clock frequency of 10-16 MHz with a memory of 16-4 KB. The excessive power of the MicroPC controller made it possible to implement some algorithms that are fundamentally impossible in other systems. The blocks are supplied with original software corresponding to the actual equipment of the plant (operational revision of the basic software in accordance with the customer's requirements specification). Software controller is open. Adding new or changing existing algorithms is possible not only when supplied by ToxSoft specialists. but also by factory programmers during operation.

The algorithms developed for the system were tested and tested at the Sayan aluminum plant for two years. During the development process, there was not a single failure in the operation of the algorithms and the effectiveness of their work with various types electrolyzers.

AT general view a block diagram of a single-circuit automatic control system is shown in Figure 1.1. The automatic control system consists of an automation object and a control system for this object. Thanks to a certain interaction between the automation object and the control scheme, the automation system as a whole provides the required result of the object's functioning, characterizing its output parameters and characteristics.

Any technological process is characterized by certain physical quantities (parameters). For the rational course of the technological process, some of its parameters must be kept constant, and some must be changed according to a certain law. During the operation of an object controlled by an automation system, the main task is to maintain rational conditions for the flow of the technological process.

Let us consider the basic principles of constructing the structures of local automatic control systems. In automatic control, as a rule, three types of problems are solved.

The first type of tasks includes maintaining one or more technological parameters at a given level. Automatic control systems, decisive tasks of this type are called stabilization systems. Examples of stabilization systems are systems for controlling the temperature and humidity of air in air conditioning units, the pressure and temperature of superheated steam in boilers, the number of revolutions in steam and gas turbines, electric motors, etc..

The second type of task is to maintain a correspondence between two dependent or one dependent and other independent quantities. Systems that regulate ratios are called tracking automatic systems, for example, automatic systems for regulating the “fuel-air” ratio in the process of fuel combustion or the ratio “steam consumption - water consumption” when feeding boilers with water, etc.

The third type of tasks is the change in the controlled variable in time according to a certain law. Systems that solve this type of problem are called software control systems. A typical example of this type of systems is the control system temperature regime during heat treatment of metal.

In recent years, extreme (search) automatic systems have been widely used to ensure the maximum positive effect of the functioning of a technological object when minimal cost raw materials, energy, etc.

A set of technical means by which one or more adjustable values ​​without the participation of a human operator are brought into line with their constant or changing set values ​​according to a certain law by developing an impact on the controlled values ​​as a result of comparing their actual values ​​with the given ones is called automatic system regulation (ACP) or automatic control system. It follows from the definition that, in the general case, the composition of the simplest ACP should include the following elements:

control object (OC) characterized by controlled value x n . x(t);

a measuring device (MD) that measures the controlled value and converts it into a form convenient for further conversion or for remote transmission;

a master device (memory) in which a setpoint signal is set that determines the set value or the law of change of the controlled variable;

comparing device (CS), in which the actual value of the controlled variable x is compared with the prescribed value g(t) and,

a deviation is detected (g(t)- x(t));

a control device (RU) that, upon receipt of a deviation (ε) at its input, produces a regulatory action that must be applied to the regulated object in order to eliminate the existing deviation of the controlled value x from the prescribed value g(t);

executive mechanism (IM). At the output of the switchgear, the regulatory action has a small power and is issued in a form that is generally not suitable for a direct impact on the object of regulation. Either strengthening of the regulatory action is required, or transformation into a convenient form x p. For this, special actuators are used, which are the executive output devices of the regulatory element;

regulatory body (RO). Actuators cannot act directly on the controlled variable. Therefore, the objects of regulation are supplied with special regulatory bodies of the RO, through which the IM acts on the regulated value;

communication lines through which signals are transmitted from element to element in an automatic system.

As an example, consider an enlarged block diagram of automatic control (Figure 1.1). In the diagram, the output parameters - the result of the operation of the controlled object, are designated x 1, x 2, ……… x n. In addition to these basic parameters, the operation of automation objects is characterized by a number of auxiliary parameters (y 1, y 2,…….y n), which must be controlled and regulated, for example, kept constant.

Figure 1.1. Structural diagram of automatic control

In the process of operation, the control object receives disturbing influences f1 .... fn, causing deviations of the parameters х1…….хn from their rational values. Information about the current values ​​of x current and y current enters the control system and is compared with their prescribed values ​​(setpoints) g1…… gn, as a result of which the control system exerts control actions E1…..En on the object, aimed at compensating for deviations of the current output parameters from the given values.

According to the structure of the automatic control system for an automation object, in particular cases, they can be single-level centralized, single-level decentralized and multi-level. At the same time, single-level control systems are called systems in which the object is controlled from one control point or from several independent ones. Single-level systems in which control is exercised from one control point are called centralized. Single-level systems in which separate parts of a complex object are controlled from independent control points are called decentralized.

2.2 Functionally - technological schemes automatic control

Functional-technological scheme - the main white paper, which determines the functional block structure of devices of nodes and elements of the automatic control system, regulation of the technological process (operations) and control of its parameters, as well as equipping the control object with devices and automation equipment. Also, circuits are often referred to simply as automation circuits. The composition and implementation rules are dictated by the requirements of the standards (see Chapter 1).

The functional-technological scheme of automation is performed on one drawing, in which the technological equipment, transport lines and pipelines, instrumentation and automation equipment are shown with symbols, indicating the links between them. Auxiliary devices (power supplies, relays, circuit breakers, switches, fuses, etc.) are not shown in the diagrams.

Functional automation diagrams are associated with production technology and process equipment, so the diagram shows the placement technological equipment Simplified, not to scale, but taking into account the actual configuration.

In addition to technological equipment functional diagrams automation in accordance with the standards simplified (two-line) and conditionally (single-line) depict transport lines for various purposes.

How to build and study circuits technical documentation must be done in a certain order.

Parameters of the technological process, which are subject to automatic control and regulation;

functional structure management;

Control loops;

The presence of protection and alarms and the accepted blocking of mechanisms;

Organization of points of control and management;

Technical means automation, with the help of which the functions of control, signaling, automatic regulation and control are solved.

To do this, it is necessary to know the principles of building automatic control systems for technological control and conditional images of technological equipment, pipelines, instruments and automation equipment, functional relationships between individual devices and automation equipment, and to have an idea of ​​the nature of the technological process and the interaction of individual installations and units of technological equipment.

On a functional diagram, communication lines and pipelines are often shown in a single-line image. The designation of the transported medium can be either numeric or alphanumeric. (For example: 1.1 or B1). The first number or letter indicates the type of medium being transported, and the next number indicates its purpose. Numeric or alphanumeric designations are presented on the shelves of leader lines or above the transport line (pipeline), and, if necessary, in breaks in the transport line (in this case, the accepted designations are explained in the drawings or in text documents(See table 1.1.). At technological facilities, they show those control and shut-off valves, technological devices that are directly involved in the control and management of the process, as well as selective (sensors), shut-off and regulatory bodies necessary to determine the relative location of sampling sites (sensor installation sites), as well as measurements or parameter control (see Table 1.2).

Complete devices (centralized control machines, control machines, telemechanics semi-sets, etc.) are designated by a rectangle of arbitrary sizes with an indication of the type of device inside the rectangle (according to the manufacturer's documentation).

In some cases, some elements of technological equipment are also depicted on diagrams in the form of rectangles indicating the names of these elements. At the same time, near the sensors, selective, receiving and other devices similar in purpose, the name of the technological equipment to which they relate is indicated.

Table 1.1. Designation of transport lines of pipelines in accordance with GOST 14.202 - 69

Table 1.2. Symbols of technological fittings

Name	Designation according to GOST 14.202 - 69
Shut-off gate valve (gate valve)
Electric valve
Three-way valve
safety valve
Rotary shutter (gate, gate)
Diaphragm actuator
Table 1.3. Output electrical switching elements
Name	Designation according to GOST 2.755 - 87
Contact for switching a high-current circuit (contactor contact)
NO contact
Break contact

To facilitate the reading of diagrams, arrows are placed on pipelines and other transport lines, indicating the direction of movement of the substance.

In the functional-technological scheme, as well as the image of the pipeline through which the substance leaves this system, an appropriate inscription is made, for example: “From the absorption shop”, “From the pumps”, “To the polymerization circuit”.

Figure 1.2. Image of sensors and selective devices (fragment)

Conventional graphic symbols of automation equipment are given in tables 1.2., 1.3., 1.4 .. Symbols of graphic symbols of electrical equipment used in automation functional diagrams should be depicted in accordance with the standards (Table 1.3.). In the absence of standard symbols for any automatic devices, you should accept your designations and explain them with an inscription on the diagram. The thickness of the lines of these designations should be 0.5 - 0.6 mm, except for the horizontal dividing line in the symbolic image of the device installed on the shield, the thickness of which is 0.2 - 0.3 mm.

The selection device for all permanently connected devices does not have a special designation, but is a thin solid line connecting the process pipeline or apparatus with the device (Fig. 1.2. Devices 2 and 3a). If it is necessary to indicate the exact location of the sampling device or the measurement point (inside the graphic designation of the technological apparatus), a circle with a diameter of 2 mm is boldly depicted at the end (Fig. 1.2 devices 1 and 4a).

Table 2.4. Conditional graphic designations of automation equipment and devices

Name	Symbol according to GOST 21.404 - 85
A primary measuring transducer (sensor) or a device installed locally (on a production line, apparatus, wall, floor, column, metal structure). Basic Allowed
Device installed on the board, remote control Basic Permissible
Selective device without permanent connection of the device
Actuating mechanism
Travel switch
Electric bell, siren, horn
Electric heater: a) resistance, c) induction
Recording device
Incandescent lamp, gas discharge (signal)
Three-phase electric machine (M - engine, G - generator)
DC electric machine (engine M, generator G)

To obtain a complete (freely readable) designation of a device or other automation tool, an alphabetic symbol is entered into its conventional graphic image in the form of a circle or oval, which determines the purpose, functions performed, characteristics and operation parameters. The location of the letter determines its meaning. Thus, the letters given in Table 1.5 are the main parameters and functions, and the letters given in Table 1.6 specify the function, parameter.

Table 1.5. Designation of the main measured parameters in automation schemes

The letter H is used to designate manual control. Reserve letters can be used to designate values ​​not provided for by the standard: A, B, C, I, N, O, Y, Z (the letter X is not recommended). Used reserve letters must be deciphered by an inscription on the free field of the scheme.

Below are the designations for specifying the values ​​of the measured quantities.

Table 1.6. Additional letter designations

The letter used to clarify the measured value is placed after the letter denoting the measured value, for example P, D - pressure difference (differential).

The functions performed by the devices for displaying information are indicated in Latin letters (see table 2.7).

Table 1.7. Function letters

Additionally, the symbols E, G, V can be used.

All of the above letter designations are put down in the upper part of the circle denoting the device (device).

If several letters are used to designate one instrument, then the order of their arrangement after the first, denoting the measured value, should be, for example: TIR - temperature measuring and recording instrument, PR - pressure recording instrument.

When designating devices made in the form of separate blocks and intended for manual operations, the letter H is put in the first place.

For an example in fig. 1.2 shows an automation scheme using recording devices for temperature and pressure drop, where for the formation symbol device (set), the functional purpose is indicated in the upper part of the circle, and its reference designation is placed in the lower part of the circle (alphanumeric or digital - 1, 2, 4a, 4b, 3a, 3b). Thus, all elements of one set, i.e. one functional group of devices (primary, intermediate and transmitting measuring transducers, a measuring device, a control device, an actuator, a regulatory body) are designated by the same number. In this case, the number 1 is assigned to the first (left) set, the number 2 - to the second, and so on.

In order to distinguish the elements of one set, an alphabetic index is placed next to the number (the letters Z and O, whose outline is similar to the outline of numbers, are not recommended): for the primary converter (sensing element) - the index "a", for the transmitting converter - "b" , for the measuring device - "in", etc. Thus, for one set, the full designation of the primary measuring transducer will be 1a, the transmitting measuring transducer 1b, the measuring (secondary) device 1c, etc. while the height of the number is 3.5 mm, the height of the letter is 2.5 mm.