Description of the block diagram of automation. Technique for reading automation schemes. Positional designations of devices, automation equipment and electric devices

The main technical document determining the structure and nature of automation of a technological object is a functional diagram of control, regulation and remote control. Functional diagrams are made in the form of drawings. Installations and units on them are depicted in the symbols adopted in the technological part of the project or in accordance with their natural appearance without respect to scale. The image of the process equipment, its individual elements and pipelines has corresponding explanatory inscriptions (name of the process equipment, its number, if any, etc.), and is also indicated by flow direction arrows. Separate units and installations of technological equipment can be shown separately from each other, but the necessary indications of their relationship are always given.

Process pipelines denoted in the same way as on the technological schemes. Automation elements (selective devices, primary and secondary devices, control devices, actuators and regulatory bodies) are designated according to GOST 21.404-85 “Conventional designations of devices and automation equipment in diagrams”.

In the functional diagrams, the installation location of the equipment should be determined:

In technological communications or directly near them, selective devices, thermocouples, resistance thermometers, diaphragms, sensitive devices of flow meters built into pipelines, regulatory bodies and related actuators are depicted;

Equipment mounted outside the boards and control panels is depicted in a rectangle with the inscription "Local devices";

The equipment placed on the panels of units, departments, installations, workshops is allocated in separate rectangles with the appropriate inscriptions, for example, “Central control panel”, “Devices on the panel”.

The image of sets of instruments and automation equipment on functional diagrams can be made in a simplified or expanded way.

A simplified method is used to display devices on flow diagrams. At simplified way the diagrams do not show primary measuring transducers and all auxiliary equipment. Instruments and automation equipment that perform complex functions (control, regulation, signaling) and are performed in the form of separate blocks are shown with one conventional graphic designation.

On the vertical lines to the instruments indicate the operating values of the controlled and adjustable parameters of the environment. The diagram shows all automation equipment (except for auxiliary equipment: relays, power supplies, filters, gearboxes, etc.).

In complex circuits, it is allowed to break the connecting lines, numbering them from the side of the selective device and from the side of the equipment. The numbers of communication lines are arranged in horizontal rows. The numbers of the communication lines of the lower row are arranged in ascending order, and the upper ones - in any order.

All communication lines between automation tools are drawn as single-line, regardless of the actual number of impulse pipes and electrical wires that actually carry out this connection.

The main requirements for the image of the connections of communication lines is the need for a clear and visual image of the functional connections of elements and automation devices from the beginning of the signal to the final place of its application.

The positional numbering of the elements and automation devices is carried out in Arabic numerals with the letter indexing of all elements sequentially from the receiving devices to the regulatory body.

The numbering of positions should be end-to-end for all functional diagrams. Bosses, pockets for installing thermal receivers and other devices included in the set of process equipment, pipelines or mounting fixtures that are made during the installation process are not assigned reference designations.

The distance between communication lines must be at least 3 mm. The thickness of the lines of the drawing must comply with GOST 2.303-68. In particular, for the image of units, process equipment, the recommended thickness of the contour lines is 0.6-1.5 mm, pipelines 0.6-1.5 mm, the image of automation equipment is 0.5-0.6 mm, communication lines are 0.2 -0.3 mm, rectangles depicting boards, consoles and local devices - 0.6-1.5 mm, callouts - 0.2-0.5 mm.

Conditional graphic designations of devices and automation equipment on the diagrams are made with a solid thick main line, and a horizontal dividing line inside the graphic designation and communication lines - with a solid thin line in accordance with GOST 2.303-68.

The font of letters is taken according to GOST 2.304-81 equal to 2.5 mm.

Symbols according to GOST 21.404-85

appliances:

a) main designation

b) allowed designation

executive mechanisms:

regulators:

According to the functional diagram of automation of technological processes, a custom specification of instruments and automation equipment is drawn up according to the form established by ESKD.

Methodology for drawing up a functional-technological scheme of automation.

The functional diagram is the main technical document that determines the structure and nature of the automation of the technological process of the designed object and equipping it with devices and automation equipment.

The functional diagram conditionally depicts technological equipment, communications, controls, instruments and automation equipment, as well as the connections between them.

An example of drawing a functional diagram of automation is shown in fig. 2.

When designing and describing functional diagrams, the terminology must comply with GOST 17194-71, and the symbols for instruments and automation equipment must comply with GOST 3925-59.

If there are technological objects of the same type (workshops, departments, installations, units, apparatuses) that are not interconnected and have the same equipment with devices and automation equipment, a functional diagram is performed for one of them, while an explanation is given on the drawing, for example, “The diagram is drawn up for unit 1; for units 2-5, the schemes are similar. To this are added explanations regarding the features in positional designations (marking) and in the specification. For example, “The specification includes equipment for five units. The marking of devices and automation equipment for units 2-5 is similar to that given for unit 1 with a change in the digital index according to the number of the unit.

To indicate on the diagrams of the designed telecontrol (TU), telesignaling (TS) and telemetry (TI) systems in the rectangles of the panels and (remote panels, horizontal lines are drawn with inscriptions on the left side of the TU, TS, TI. The connection of these systems with instruments and automation equipment is shown by lines technological equipment and communications of an automated object are depicted on functional diagrams in a simplified way, but in such a way as to show their relative position and interaction with devices and automation equipment.It is allowed to depict parts of the object in the form of rectangles indicating their names. 3464-63) show only those regulating and shut-off bodies that are involved in the process control system.On the pipeline lines, the diameters of the conditional passages are indicated and the arrows indicate the directions of the flow of the substance in accordance with the technological scheme.

Instruments and automation tools built into technological equipment and communications or mechanically associated with it are depicted on functional diagrams in close proximity to technological equipment. These include: selective devices for pressure, level, composition of the substance, receiving devices that perceive the effects of measured and controlled quantities (narrowing devices, rotameters, resistance thermometers, thermocylinders of manometric thermometers, thermocouples, etc.), actuators, regulating and shut-off bodies .

Instruments and automation equipment that do not have a direct structural-mechanical connection with process equipment are shown in rectangles located at the bottom of the drawing field. These include: primary transducers (sensors) operating in a set with selected devices, transducers, amplifiers; instruments and control equipment, etc. . They are located on the diagram in one or more horizontal rows and are conditionally limited to rectangles.

Their names are indicated in the rectangle on the left: “Local devices”, “Control panel”, etc. Auxiliary equipment and devices (, filters and pneumatic supply reducers, fuses, magnetic starters, etc.) that do not affect the functional structure of the automation circuit are not shown in the diagrams.

The exception is magnetic starters used in control loops to control actuators. The devices on the boards are shown on the diagram conditionally in the lower rectangle, local devices are located above it.

The communication lines on the functional diagram are depicted as one line, depending on the number of wires and pipes that make this connection, and are applied with the least number of kinks and intersections. Communication lines should clearly display the functional relationships between circuit elements from the beginning of the signal to the end. It is allowed to combine blocking communication lines into one common line. For the convenience of reading automation functional diagrams with a large number of technological equipment and automation tools, it is allowed to draw a rectangle with inscriptions under the rectangles of panels and consoles explaining the purpose of the depicted automation tools.

On the diagrams, all devices and automation equipment are assigned positional designations.

The designations uniquely identify the type and installation location of the device. Each set of automation tools is assigned a serial number (for example, set 1 in Fig. 2). A set is considered functionally-related devices that perform a specific task. Each device of the kit is assigned an alphanumeric designation, consisting of the serial number of the kit and an alphabetic index.

On the drawings of functional diagrams, on the right side above the stamp of the drawing, a specification (one of the variants of the diagrams) is placed, which is the source material for compiling application lists and order specifications. If the project provides for the use of new technological equipment, then its specification is placed first, then the specification for automation equipment is placed, moreover, in the groups “local devices”, “devices on boards”.

The specification includes all devices that are assigned reference designations in the diagrams.

Designations of basic quantities and conditional images of devices and automation equipment in diagrams.

GOST 3925-59 establishes the designations of measured and controlled quantities and conditional images of instruments and automation devices used in functional diagrams. These include the designations of the main controlled and adjustable quantities, the names of the main electrical measuring instruments, as well as images of measuring and regulating instruments, types of transmissions for remote action, primary converters that perceive the impact of measured or controlled quantities, actuators and regulatory bodies, additional devices and recommended image sizes devices and means.

GOST gives examples of the use of conditional images of devices, regulators direct action, control devices, consisting of several links, and the designation of controlled and adjustable values, as well as an example of an image of a functional diagram of automation.

When developing an automation project, first of all, it is necessary to decide from which places certain sections of the object will be controlled, where control points, operator premises will be located, what should be the relationship between them, i.e. it is necessary to resolve the issues of choosing a management structure. The control structure is understood as a set of parts of an automatic system into which it can be divided according to a certain attribute, as well as ways of transferring influences between them. A graphic representation of the control structure is called a block diagram. Although the initial data for the selection of the control structure and its hierarchy are specified with varying degrees of detail by the customer when issuing a design assignment, the complete control structure must be developed by the design organization.

The choice of the control structure of the automation object has a significant impact on the efficiency of its work, reducing the relative cost of the control system, its reliability, maintainability, etc.

In general, any system can be represented by:

constructive structure;

functional structure;

algorithmic structure.

In the constructive structure of the system, each part of it is an independent constructive whole.

The design scheme contains:

Object and automation system;

Information and control flows.

In the algorithmic structure, each part is designed to perform a specific input signal conversion algorithm, which is part of the entire system operation algorithm.

The designer develops an algorithmic block diagram (ACS) of the automation object according to differential equations or graphical characteristics. The automation object is represented as several links with different transfer functions interconnected. In the ACC, individual links may not have physical integrity, but their connection (the circuit as a whole) in terms of static and dynamic properties, in terms of the functioning algorithm, should be equivalent to the automation object. Figure 9.2 gives an example of ACC ACS.

AT functional structure each part is designed to perform a specific function.

In automation projects, structural block diagrams are depicted with elements of functional features. Complete information about the functional structure, indicating local control loops, control channels and process control, is given in the functional diagrams.

The block diagram of the APCS is developed at the “Project” stage in a two-stage design and corresponds to the composition of the system.

The block diagram displays in a general view the main decisions of the project on the functional, organizational and technical structures of the automated process control system in compliance with the hierarchy of the system and the relationship between control and management points, operational personnel and the technological control object. Accepted at runtime block diagram the principles of organizing the operational management of a technological object, the composition and designations of individual elements of the block diagram must be preserved in all design documents for the process control system.

The block diagram shows the following elements:

Technological subdivisions (departments, sections, shops, productions);

Points of control and management (local boards, operator and dispatch centers, block shields etc.);

Technological personnel (operational) and additional special services providing operational management;

The main functions and technical means that ensure their implementation at each control and management point;

The relationship between departments and with the higher ACS.

The block diagram of the automation system is performed by nodes and includes all elements of the system from the sensor to the regulatory body, indicating the location, showing their interconnection.

Structural diagram (according to GOST) is a diagram that defines the main functional parts of the automation system, their purpose and relationships. For automatic systems often make up skeletal block diagrams.

The block diagram of automation is intended to determine the control and management system of the TP of a given facility and to establish links between panels and control panels, units, and operator workstations. The block diagram is the main design document, which establishes the optimal channels for administrative, technical and operator control. They reflect the features of TP and TSA when creating local control and automation systems.

The block diagram in general terms reflects the complex used technical means automation, the principle of interaction of a technological object with a control device and operational personnel.

We will build the structure of the control system of the press for casting the bottom of shoes based on the control loops of individual technological parameters. The construction of a block diagram in a general form will allow you to clarify it when choosing a TSA and arranging the selected equipment.

On this equipment, two control objects can be distinguished: OU1 - mold, OU2 - injection system.

For the first object, it is necessary to control the position (Figure 2.1 DP1, DP2) and the temperature of the mold (Figure 2.1 DT1).

In OU2, we select the following parameters: temperature in three heating zones (Figure 2.1 DT2, DT3, DT4), melt pressure (Figure 2.1 DT1), thermoplastic elastomer level in the hopper (Figure 2.1 DN1), screw rotation speed during the cycle (Figure 2.1 DH1 ).

Electrical signals from the measuring transducers are fed to the control device. The most promising will be the use of an industrial controller. The presence of built-in memory (RAM), timers, counters, a lot of discrete and analog inputs and outputs, the ability to connect additional modules, expanding the possibilities of use, a unified output signal - all this speaks in favor of the use of an industrial controller.

Part of the block diagram showing the devices for influencing the technological object has a general view and is presented in the form of 9 power converters (PR1 - PR9) and 9 actuators (IM1 - IM9).

IM1 - mold drive;

IM2 - ejector drive;

IM3 - voltage regulator supplied to the heating elements of the mold;

IM4 - cooling system engine;

IM5, IM6, IM7 - voltage regulator supplied to the heating elements of the injection system;

IM8 - screw rotation motor;

IM9 - valve for supplying the melt into the mold.

Power converters are needed to convert the control signal of an industrial controller into a power signal that acts directly on the IM.

The block diagram also shows the control panel (CP), the alarm unit (BAS) and the presence of a communication channel with the enterprise's automated control system.

The block diagram is shown in Figure 2.1

Figure 2.1 - Block diagram of automation

Block diagrams automation in automation projects is recommended to be developed in accordance with GOST 24.302-80. System technical documentation on ASU. General requirements to the implementation of schemes (p. 2.1, 2.2, 2.6).

The graphic construction of the scheme should give the most visual representation of the sequence of interaction of functional parts in the product. On the lines of interaction it is recommended by arrows (according to GOST 2.721-74) indicate the direction of the course of processes occurring in the product.

The block diagram displays in a general view the main decisions of the project in terms of functional, organizational and technical structures automated system process control (APCS) in compliance with the hierarchy of the system and the relationship between control and management points, operational personnel and the technological control object. The principles of organizing the operational management of a technological object, the composition and designations of individual elements of the structural diagram adopted during the implementation of the block diagram, must be preserved in all design documents for the process control system, in which they are concretized and detailed in the functional diagrams of automation, the block diagram of the complex of technical means (CTS) of the system, schematic diagrams of control and management, as well as in project documents related to the organization of operational communications and organizational support for automated process control systems.

Starting materials for the development of block diagrams are:

assignment for the design of automated process control systems;
fundamental technological schemes the main and auxiliary production facilities of the technological facility;
assignment for the design of operational communication of the subdivisions of the automated technological facility;
master plan and title list of the technological facility.

The block diagram is developed at the stages of "project" and "working draft". On the stage " working documentation» with two-stage design, a block diagram is developed only in case of changes in the technological part of the project or decisions on the automated process control system adopted during the approval of the automation project.

As an example on rice. 8.4 a block diagram of the management of sulfuric acid production is given.

On the block diagram show:

technological subdivisions of the automated object (departments, sections, workshops, productions);
monitoring and control points (local boards, operator and dispatching stations, etc.), including those not included in the project being developed, but having a connection with the designed control and management systems;
technological (operational) personnel and specialized services, providing operational control and normal functioning of the technological object;
the main functions and technical means (devices) that ensure their implementation at each control and management point;
the relationship between the divisions of the technological facility, points of control and management and technological personnel among themselves and with the superior control system (ACS).

Rice. 8.4. A fragment of the block diagram of the management and control of sulfuric acid production: 1-line communication with the workshop chemical laboratory; 2 - communication line with points of control and management of the acid site; 3 - communication line with the point of control and management of III and IV technological lines

The function of the automated process control system and their symbols in fig. 8.4

Table 8.1

Symbol	Name
	Parameter control
	Remote control technological equipment and executive devices
	Measuring conversion
	Monitoring and signaling of equipment status and parameter deviations
	Stabilizing regulation
	Selection of the operating mode of the regulators and manual control of the setpoints
	Manual data entry
	Registration of parameters
	Calculation of technical and economic indicators
	Accounting for production and compiling data per shift
	Diagnostics of technological lines (aggregates)
	Load distribution of technological lines (aggregates)
	Optimization of individual technological processes
	Analysis of the state of the technological process
	Forecasting of key production indicators
	Evaluation of shift work
	Monitoring the implementation of planned targets
	Repair control
	Preparation and issuance operational information in the automated control system
	Receipt of production constraints and tasks from the automated control system

Elements of the block diagram are depicted, as a rule, in the form of rectangles. Separate functional services [department of chief power engineer (OGE), department of chief mechanic (OGM), department technical control(OTC), etc.] and officials (director, chief engineer, shop foreman, shift supervisor, foreman, etc.) may be depicted in the block diagram in the form of circles.

Inside the rectangles depicting sections (subdivisions) of the automated object, their production structure is revealed. At the same time, workshops, sections, production lines or groups of units are allocated to perform the completed stage of the technological process, which are essential for disclosing in the project documents all the relationships between the controlled (technological control object) and control systems.

On the diagram, the functions of the automated process control system can be indicated in the form symbols, the decoding of which is given in the table on the drawing field ( table 8.1).

The name of the elements of the production structure must correspond to the technological part of the project and the names used in the implementation of other documents of the APCS project.

The relationship between control and management points, technological personnel and the control object is depicted in the diagram by solid lines. The merging and branching of lines are shown in the drawing by broken lines ( fig.8.4).

If there are similar technological objects (workshops, departments, sections, etc.), it is allowed to disclose the control structure on the diagram for only one object. Necessary explanations for this are given in the diagram.

From the block diagram to fig.8.4 It follows that the control system for the main technological processes of sulfuric acid production is four-level:

the first level - local control of units carried out by apparatchiks from working posts;
the second level - centralized control of several units included in one or another technological section, carried out by a senior apparatchik;
third level - centralized management of several sites included in I and II (or III and IV) technological lines of sulfuric acid production;
the fourth level - control from the dispatcher's office of all technological lines of sulfuric acid production, carried out by the dispatcher.

Structural diagrams are executed, as a rule, on one sheet. Table with symbols ( table 8.1) is located in the field of the diagram drawing above the title block. The table is filled from top to bottom. With a large number of symbols, the continuation of the table is placed to the left of the main inscription with the same filling order. The main inscription and additional columns to it are performed in accordance with GOST 21.103-78.

The thickness of the lines in the diagram is chosen in accordance with GOST 2.303-68. Recommended to use for conditional images lines 0.5 mm thick; for communication lines - 1 mm; for other lines - 0.2 - 0.3 mm.

The sizes of numbers and letters for inscriptions are selected in accordance with GOST 2.304-81. Explanatory text should be in accordance with GOST 2.316-68. The text part placed on the drawing field is placed above the main inscription. It is not allowed to place images, tables, etc. between text and main inscriptions. Paragraphs of the explanatory text should be consecutively numbered. Each item is written from the red line. The heading "Note" is not written. Abbreviations of words are not allowed in the text and inscriptions, with the exception of generally accepted ones, as well as those established by annexes to GOST 2.316-68 and GOST 2.105-95.

The sizes of all conditional images are not regulated and are chosen at the discretion of the performer, observing the same sizes for images of the same type.

At present, for technological control and automatic control, aggregated systems of telemechanics, complexes of technical means of local measuring and control systems, aggregated control and regulation systems, electrical centralized, etc. are widely used.

As a rule, aggregated complexes are made on the basis of elements of microelectronic equipment, they have a developed and flexible system of connections between the devices included in it, as well as with the control object and maintenance personnel, which provides quite ample opportunities for their use in various layout options and operating modes.

Personal computers and PC networks are widely used for the layout of various structures of automated process control systems in the energy, chemical, petrochemical, oil refining, gas, metallurgical, metalworking, mining, instrument-making, pulp and paper and other industries.

They allow the following information and computing functions APCS:

collection, primary processing and storage of information;
indirect measurements of process parameters and the state of technological equipment;
signaling the state of the parameters of the technological process and equipment;
calculation of technical, economic and operational indicators of the technological process and technological equipment;
preparation of information for higher and related systems and levels of management;
registration of process parameters, equipment conditions and calculation results;
control and registration of deviations of the process parameters and the state of the equipment from the specified ones;
analysis of operation of interlocks and protections of technological equipment;
diagnostics and forecasting of the course of the technological process and the state of technological equipment;
prompt display of information and recommendations for the maintenance of the technological process and the management of technological equipment;
implementation of procedures for automatic exchange of information with higher and related control systems.

On the basis of industrial UEVMs, control computer complexes (CCS) are implemented that perform various functions, including:

regulation of individual parameters of the technological process;
single-cycle logic control;
cascade regulation;
multi-coupled regulation;
software and logical operations of discrete control of the process and equipment;
optimal control of the steady state of the technological process and equipment operation;
optimal control of the transient process;
optimal control of the technological object as a whole.

In the automation project, it is necessary to select and arrange the aggregated complexes of technical means and automation means, i.e. on the basis of typical technical means, develop a block diagram of technological control and management of certain parameters of a given automation object.

On the structural diagram, the aggregated and modular elements of the complex of technical means and automation tools are depicted in the form of rectangles with indication of symbols in them. The decoding of these designations with an indication of their functions is made in the table placed on the diagram drawing. The connection between the elements of the circuit is depicted by lines with arrows showing the direction of the signals.

As an example on fig.8.5 a simplified block diagram of the technical support of the automated process control system for blast furnace No. 9 of the Krivoy Rog Metallurgical Plant, built using UVK tools, is given. The blast furnace has a conveyor system for supplying materials to the top. The collection of information about the operation of the blast furnace, conveyor system, charge supply and other systems is carried out by level sensors DU in charge rooms and sensors of the type of material DVM in intermediate hoppers, signaling devices C for the presence and type of materials on conveyors for overflowing chutes and intermediate funnels, pressure and pressure drop sensors DDPD in separate cavities of the loading device, sensors of the angle of rotation of the DUP tray of the loading device, temperature sensors DT, flow sensors DR, etc.

Processing and provision of information, stabilization or change of technological parameters according to a given program, input of information into the UVM and output of recommendations for controlling the operation of the blast furnace, and other operations are carried out using technical means for centralized control and management of the operation of the blast furnace.

When developing projects for the automation of complex technological processes using aggregated computer technology systems that require preliminary research and experimental work in the conditions of operating equipment during the development of design capacities, phased implementation should be provided. installation work and the inclusion of UVK in the work.

1) start the object with technological control and automatic control from local control systems; during this period, the dynamic and static characteristics of the object are specified, errors in installation and design, possible defects in process equipment are eliminated, and technological process etc.; programs and algorithms are being worked out on the UVM without their connection to the existing technological equipment;

2) connection of the CCM to the operating technological equipment and its inclusion in the "adviser" mode with the issuance of recommendations to the operating personnel on controlling the operation of the blast furnace;

3) turning on the UVM in the mode of automatic control of the object through local control systems.

If necessary, in automation projects, block diagrams of individual complexes of technical means and automation tools are given.

Rice. 8.5. Simplified block diagram of the process control system for blast furnace No. 9 of the Krivoy Rog Metallurgical Plant

DNM - sensors for the presence of materials; DU - level sensors; DV - mass sensors; ASHiK - charge and coke analyzers; VK - coke moisture meter; DVM - material type sensors; DRLC - conveyor belt break sensors; PVMB - feeders for issuing materials from bunkers; IM - executive mechanisms; DT - temperature sensors; DDPD - pressure or differential pressure sensors; DR - flow sensors; DVl - humidity sensors; ADiG - blast and gas analyzers; DUP - rotation angle sensors; TK - television cameras; ST - signal board; VP - secondary devices; MS - mnemonic diagrams; KU - control keys; RZVD - manual dose weight transmitters; LSDM - local dosing systems for materials; LSR - local control systems; BCIC - block digital indication with frequency inputs; RDZ - manual remote transmitters; QI - digital indicators; IPM-indicators of the position of mechanisms; TV - TV sets; COMPUTER SHP - electronic computer for charge supply (controlling the weighing of materials and the performance of the SHP tract); TsVU SSK - a digital computing device of the centralized control system (which collects and processes primary information, calculates complex and specific indicators of the furnace, automatically fills in reporting documents); BCR - block of digital registration; BCID - digital indication unit with discrete inputs; COMPUTER UHDP - an electronic computer that controls the thermal state and operation of the furnace; IT - information boards; I - the first stage of implementation (start-up complex); II and III, respectively, the second and third stages of implementation.

18 Calculation methods for determining the settings of controllers in LSU

19 LSU modeling

Modeling, in a general sense, is the representation of a phenomenon (process) by some description.

The description can be verbal, in the form of models:

Physical modeling- this is the study of objects on physical models, which are some objects that retain the physical nature of the original object, or are described by mathematical equations similar to equations. describing the original object. An example of the first type of simulation is the study of the aerodynamic properties of an aircraft or a car on mock-ups, an example of the second type is the simulation of a pendulum using an RLC chain (oscillatory link).

Math modeling- MM - a record in the language of mathematics of the laws governing the flow of the process under study or describing the functioning of the object under study. MM is a compromise between the infinite complexity of the object or phenomenon under study and the desired simplicity of its description.

MM must be complete enough for that. so that you can study the properties of the object and at the same time simple to do so. so that its analysis by means existing in mathematics and computer technology is possible.

Simulation is based on the reproduction by means of a computer of the process of the functioning of the system deployed in time, taking into account the interaction with external environment. The basis of any simulation model (IM) is: the development of a model of the system under study, the choice of informative characteristics of the object, the construction of a model of the impact of the external environment on the system, the choice of a method for studying the simulation model. Conditionally, the simulation model can be represented in the form of operating, software (or hardware) implemented blocks. The block of imitation of external influences (EIVI) generates realizations of random or deterministic processes simulating the influence of the external environment on the object. The results processing block (RB) is designed to obtain informative characteristics of the object under study. The information necessary for this comes from the block of the mathematical model of the object (BMO). The control unit (BUIM) implements a method for studying a simulation model, its main purpose is to automate the process of conducting IE.

The purpose of simulation is the design of the IM of the object and the implementation of IE over it to study the law of functioning and behavior, taking into account the given restrictions and target functions in conditions of imitation and interaction with the external environment. The advantages of the simulation method include: 1. conducting an IE over the MM of a system for which a full-scale experiment is not feasible for ethical reasons or the experiment is associated with a danger to life, or it is expensive, or because the experiment cannot be carried out with the past ; 2. problem solving, analytical methods for which they are not applicable, for example, in the case of continuous-discrete factors, random effects, nonlinear characteristics of system elements, etc.; 3. the ability to analyze system-wide situations and make decisions with the help of a computer, including for such complex systems, the choice of a criterion for comparing behavior strategies for which at the design level is not feasible; 4.reduction of terms and search for design solutions that are optimal according to some criteria; evaluation of efficiency; 5. analysis of options for the structure of large systems, various control algorithms for studying the influence of changes in system parameters on its characteristics, etc. The task of simulation modeling is to obtain the trajectory of the system under consideration in n - dimensional space (Z 1 , Z 2 , ... Z n), as well as the calculation of some indicators that depend on the output signals of the system and characterize its properties. Basic simulation methods: Analytical method is used to simulate processes mainly for small and simple systems, where there is no randomness factor. Statistical modeling method originally developed as a method of statistical testing. This is a numerical method that consists in obtaining estimates of probabilistic characteristics that coincide with the solution of analytical problems (for example, with the solution of equations and the calculation of a definite integral). Combined method(analytical-statistical) allows you to combine the advantages of analytical and statistical methods modeling. It is used in the case of developing a model consisting of various modules representing a set of both statistical and analytical models that interact as a whole. Moreover, the set of modules can include not only modules corresponding to dynamic models, but also modules corresponding to static mathematical models.

20 Assessment of the quality of LSU functioning

Automatic control systems should not only be stable, but also ensure the quality of the control process. The main most significant requirements for the quality of management, which allow you to evaluate the performance of almost all management systems, are called indicators of the management process. They characterize the behavior of the system in the transition process. The quality indicators will be the regulation time, overshoot, process oscillation, steady-state error, the nature of the attenuation of the transient process, and the stability margin.

The quality of control processes is usually assessed by the transition function, which is the system's response to external influences such as a single jump. For servo systems and program control, the transition function is considered in relation to the master action, and for stabilization systems, in relation to the perturbation.

Figure 1. Determination of quality indicators of regulation by transient response.

On fig. 1 shows the transition function by which it is possible to determine the main indicators of the quality of the transition process: regulation time, overshoot, etc.

The regulation time determines the duration of the transient process. Theoretically, the transient process lasts indefinitely, but in practice it is considered complete as soon as the deviation of the controlled variable from its new steady-state value does not exceed the permissible limits.

The regulation time is the minimum time after which, starting from the moment the input signal begins, the output variable deviates from the steady value by an amount not exceeding some given constant value of 0.5.

The regulation time characterizes the speed of the system.

The performance can be characterized both by the time the transition function reaches a new steady state value and the time it takes to reach the maximum value.

Overshoot is the maximum deviation of the controlled value from the set value and expressed as a percentage.

Regulating time and overshoot are interrelated. Thus, the overshoot depends on the rate of change of the controlled variable, which graphically represents the tangent of the slope angle α (alpha) of the tangent at point A to the curve (Figure 1).

The greater this speed, the greater the overshoot. Therefore, to reduce it, it is necessary to reduce the speed with which the system approaches a new steady state. But this will lead to an increase in the regulation time. If the system approaches the steady state at zero speed, then there will be no overshoot at all, but the control time will increase significantly (Figure 2).

Figure 2. Step response of an automatic control system without overshoot.

The values of the control time and overshoot are often set as initial data for the synthesis of corrective devices, since the correct choice and adjustment of the latter ensures the suppression of unwanted fluctuations in the controlled variable in the transient process. For some systems, overshoot is generally unacceptable, for example, for systems of automatic control of physical quantities in processes related to the preparation of products. It must also be borne in mind that the desire to reduce the regulation time leads to an increase in the power of the actuator.

The fluctuation of the process is characterized by the number of fluctuations of the controlled variable during the regulation time.

Oscillation is quantitatively estimated by the logarithmic damping decrement, which is the natural logarithm of the ratio of two subsequent deviation amplitudes of the controlled variable in one direction.

The larger the logarithmic damping decrement, the faster the damping of the transient.

The steady error indicates the accuracy of the control in steady state. It is equal to the difference between the set value of the controlled variable and its steady state value under normal load.

The nature of the attenuation of the transient process allows us to classify transient processes in control systems and distinguish four main types among their diversity (Figure 3): oscillatory process (curve 1) - it has several overshoot values; low-oscillatory process (curve 2) – process with one overshoot; monotonic process (curve 4), in which the rate of change of the controlled variable does not change sign during the entire time of regulation; aperiodic process (curve 3) is a process when the controlled value is less than its steady-state value with an accuracy up to the dead zone of the controller for all values of the control time.

Figure 3. The main types of characteristics of transient processes of automatic control systems for a typical single impact.

The stability margin is the physical essence and methods for determining this indicator of control quality.

Indicators that characterize the quality of the system in the transition mode are divided into direct and indirect.

Direct indicators are numerical quality estimates obtained directly from the transient response. To obtain direct quality indicators, it is necessary to have a transient curve, which can be built according to the block diagram or differential equation of automatic control systems using analog computers or computers.

Indirect estimates of the quality of the transient process make it possible to determine some features of the transient process and establish the influence of system parameters on the quality of transient processes. Indirect quality indicators include root, frequency and integral estimates.

Consider the root quality estimates. Geometrically, the degree of stability can be defined as the distance on the plane from the imaginary axis to the root closest to it or the nearest pair of complex roots (Figure 4).

Figure 4. Root estimates of the quality of automatic control systems.

The concept of the degree of stability is used for the synthesis of automatic control systems.

Consider frequency quality estimates. With harmonic effects, the quality of automatic control systems is usually evaluated by frequency characteristics. For this, the following quantities are used: the oscillation index and the cutoff frequency. The oscillation index is the ratio of the maximum value of the amplitude-frequency characteristic of a closed system to its value at a frequency equal to zero. The cutoff frequency is the frequency at which the frequency response is equal to unity. Indirectly, it characterizes the duration of the transition process.

Let us consider integral quality estimates. The transient curve can be used to evaluate the quality of the regulation process in a given system. Indirectly, the quality of regulation can be assessed by the area between the transient curve and the steady state line. In this case, the quality criterion will be a certain time integral of the function that characterizes the difference between the actual and specified values of the controlled variable.

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