Basics of automation of production processes. Fundamentals of automation of technological processes in oil and gas production

PREFACE

INTRODUCTION

Chapter 1. GENERAL INFORMATION ABOUT AUTOMATIC CONTROL OF PRODUCTION PROCESSES, CLASSIFICATION OF AUTOMATIC CONTROL SYSTEMS (ACS)

1.1 Basic concepts and definitions of the theory of automatic control

1.1 Regulatory principles

1.3 Algorithm (law) of regulation5

1.4 Basic requirements for automatic control systems

2 Transfer functions linear system. Block diagrams and their transformations

3 Statics of automatic control systems

3.1 Static characteristics of ACS elements and links

3.2 Static characteristics of link connections

4 The concept of stability of automatic control systems

Chapter 2. METROLOGICAL CHARACTERISTICS OF TECHNICAL MEASUREMENTS

2.1 Basic metrological terms and definitions. Measurement concept

2 Types of measuring instruments (MI)

3 Systems and units of physical quantities

4 Metrological characteristics of measuring instruments. Calibration and verification of measuring instruments

Chapter 3. ELECTRICAL SENSORS OF MECHANICAL QUANTITIES

3.1 Linear and angular displacement sensors

2 Force sensors

3 Rotation speed sensors

Chapter 4. METHODS AND TOOLS FOR MEASUREMENT OF BASIC TECHNOLOGICAL PARAMETERS

4.1 Electrical measurement methods

2 Methods and means of measuring temperature

3 Methods and means of level measurement

4 Methods and means of measuring pressure

4.1 Direct pressure measurement methods

4.2 Methods for indirect pressure measurements

5 Methods and means of flow measurement

5.1 Variable pressure flow meters

5.2 Constant differential pressure flow meters

5.3 Electromagnetic flow meters

5.4 Ultrasonic flow meters

5.5 Variable level flow meters

5.6 Thermal flow meters

5.7 Vortex flowmeters

5.8 Coriolis flow meters

Chapter 5. METHODS AND TOOLS FOR MEASURING VIBRATION

5.1 Vibration measurement methods

2 Vibration measurement tools

Chapter 6. MEASUREMENT OF PHYSICAL AND CHEMICAL PROPERTIES OF LIQUIDS AND GASES

6.1 Measurement physical and chemical properties oil and formation waters

1.1 Measurement of physical and chemical properties of oil

1.2 Measurement of physical and chemical properties of produced water

2 Measurement of physical and chemical properties of gases

Chapter 7. RELAY ELEMENTS

7.1 Electromagnetic relays for direct and alternating current

1.1 Electromagnetic relays permanent (neutral)

1.2 AC electromagnetic relays

2 Magnetic contacts (reed switches)

Chapter 8. TRANSMISSION OF INFORMATION IN AUTOMATION SYSTEMS

8.1 Basic information about telemechanics systems

2 Data interfaces

Chapter 9. MICROPROCESSORS

9.1 Basic information about microprocessors

2 Analog-to-digital and digital-to-analog conversion of information

CONCLUSION

LITERATURE

APPLICATIONS

Appendix 1. Test materials

Appendix 2. List of practical and laboratory work

Appendix 3. List of topics for calculation and graphic works (abstracts)

Appendix 4. List of basic and additional literature

PREFACE

Tutorial “Fundamentals of Automation” technological processes oil and gas production" contains a systematic presentation of the academic discipline of the same name, fully complies curriculum, and, in fact, is the main educational book on the discipline. It reflects the basic knowledge defined by the didactic units of the Federal State educational standard in the direction of 131000 “Oil and Gas Engineering”, specialty “Operation and Maintenance of Oil Production Facilities”. Content teaching aid includes a description of methods for obtaining and using knowledge in the field of automation of technological processes, methodological foundations of basic methods and patterns of functioning of measuring instruments and automation systems and the development of the areas of activity reflected in them, as well as key problems and most important trends in the development of the oil and gas industry.

The purpose of the textbook is to provide methodological assistance to students in creating the necessary initial theoretical knowledge base for students on the basic principles of building automation systems for production processes, as well as on the technical means of automation on the basis of which the mentioned systems are built. When studying educational material the student will receive information about the basics of automation of measurement processes, types and methods of measurement, the design and operating features of specific sensors of basic technological parameters, secondary devices and microprocessor technology.

The purpose of the manual is to provide students with the opportunity to study the structure and operating principle of specific equipment and automation equipment, as well as some rules for their operation.

In the process of studying the material, students should become familiar with the basics and classification of methods and measuring instruments; get a clear idea of the technological complex, the points where the signal of technological process parameters is collected; learn circuit diagrams equipment, principles of operation of sensors and relays, technical capabilities of microprocessor equipment and automation equipment, rules for constructing block diagrams, regulation criteria, prospects for the introduction of computers in the development and operation of wells, rules for technically competent operation of equipment and automation equipment; acquire skills in conducting comparative analysis control and automation equipment; learn about the difficulties of using automation tools and the prospects for their development.

Based on the acquired theoretical knowledge, students must learn to perform practical and laboratory work, and subsequently be able to install simple equipment, decipher and analyze equipment recording diagrams, evaluate the information received, adjust the development and operation modes of automation systems for oil and gas production processes using specialized equipment.

INTRODUCTION

Automation of technological processes is a decisive factor in increasing labor productivity and improving the quality of products.

Technological processes of modern industrial facilities require control large number parameters and difficult to manage. In this regard, during the design and operation industrial installations exceptional importance is attached to the issues of professionalism of specialists working at fuel and energy complex enterprises.

Over the years of development of oil refining and petrochemical industry There is an increase in the complexity of processes, which requires more precise management of them. In the first half of the 20th century, instruments for recording and monitoring parameters, the so-called instrumentation and control devices, appeared. The origin, formation and development of measurement and control devices, the process from automatic control to automated control systems and control at the macro and micro levels is an integral part of the processes of oil and gas production, oil refining and petrochemicals.

Further improvement of instruments for recording, monitoring and controlling parameters led to automation and telemechanization of oil refining and petrochemicals. The latter led to computerization and process management, that is, to automated control systems (ACS).

And, naturally, progress in instrument making and hardware engineering in automated control systems is an interesting problem, the solution of which is necessary to determine further prospects for development based on overcoming global problems management in the oil and gas sector.

Six main modern problems operational production management and automation in oil and gas production:

Accounting for the production, movement and use of hydrocarbon raw materials, oil, gas, petroleum products, for the solution of which it is important to ensure the ability to monitor accounting operations, including from licensed areas, as well as to ensure internal and external audits of oil accounting, which in turn requires the development relevant measuring instruments, as well as software and information systems.

Management of territorial assets, organization maintenance and repair of equipment, ensuring the safety of production and personnel. To solve this problem, it is necessary to develop software and information tools that provide accounting, planning of maintenance and repairs, monitoring the condition of production assets and work performed; control over the conclusion and implementation of contracts with contractors for the performance of work; control over the presence of personnel at production facilities; possibility of training personnel on site using simulators; availability at workplaces of up-to-date documentation on the use of equipment, on the technology for performing procedures and operations.

High level of energy consumption in production and the need for energy saving and energy efficiency measures. To solve this problem, software and information tools are required to provide accounting, planning of maintenance and repairs, monitoring the state of energy consumption by elements of the technological process; identification of energy consumption facilities with excess levels of electricity consumption; control over the implementation of energy saving measures.

A variety of automated process control tools that simulate and information systems. This problem requires the development of software and information tools that ensure the formation of an array of initial information for strategic (plans for development and production location), medium-term (annual and monthly plans) and operational (daily and shift plans) management plans; meeting the requirements for the composition and structure of documents in accordance with the internal regulations of the enterprise, the requirements for standardization of shareholders; unification of access and differentiation of powers when working with documents.

Minimizing the cost of operating the system while maximizing the level of information service provided to decision makers. To solve the problem, the following is required: development of a methodology for performing work on the development of the MES level, automation of previously non-automated production facilities and software and information tools ensuring: maintaining databases up to date and system software in working condition; control of the functioning of the system software (for information exchange with automated process control systems, ERP, etc.); recording the actions of personnel involved in the operation of the system.

The increase in funds and labor required to extract each ton of oil, due to the fact that cheap oil fields in Western Siberia, discovered in the late 1950s, are gradually depleted. In the oil-bearing region, there are mainly reserves with difficult extraction that require new technological solutions and additional capital investments. To solve this problem, it is necessary to increase the efficiency of capital investments and facilitate oil recovery management; increase the efficiency of capital investments and facilitate the management of oil extraction from the subsoil through an approach called “smart fields”, “smart fields”, “smart oil fields”, “smart wells”; optimize the operation of all field facilities: wells, reservoirs, pipelines and other surface facilities.

Chapter 1. GENERAL INFORMATION ABOUT AUTOMATIC CONTROL OF PRODUCTION PROCESSES, CLASSIFICATION OF AUTOMATIC CONTROL SYSTEMS (ACS)

1Basic concepts and definitions of the theory of automatic control

It is known that technical process characterized by a set of data, values, indicators. The set of operations for starting, stopping a process, maintaining constant process indicators or changing them according to a given law is called control.

Maintaining indicators at a given level or changing them according to a given law is called regulation, i.e. regulation is part of management. And if these control processes are carried out without human (operator) participation, then they are called automatic.

A device that carries out a technological process, the indicators of which need to be controlled or regulated, is called a control object, or a controlled object. Control objects can be a drilling pump, a drilling rig, a drilling rig drive, etc., or their individual components that perform certain operations of the technological process, for example, a drilling rig winch.

A technical device that carries out control in accordance with a program (algorithm) is called an automatic control device.

The combination of a control object and a control device is called a system automatic control(self-propelled guns).

We are not interested in all automatic control operations, but only in regulation, i.e. those operations that relate to maintaining or changing process indicators.

Any regulatory process can be carried out

· without control of the result - open-loop regulation;

· with control of the result - closed-loop regulation.

An example of open-loop regulation without monitoring the result (flow Q) is the stabilization of the supply of flushing liquid Q during operation piston pump on full performance when the corresponding gearbox speed is turned on (unregulated drive and no flushing fluid discharge). Here, in case of significant (non-emergency) changes in the characteristics of the hydraulic path (due to sludge in the bottom hole, falling out of pieces of rock from the walls of the well, etc.), the flow rate of the flushing fluid remains constant.

In the given example, the control object is a mud pump with a fixed drive ( pumping unit). The control (regulatory) body, which must contain an object to control the supply of flushing fluid, is the gearbox.

Open-loop regulation is used much less frequently than closed-loop regulation due to the instability of the characteristics of the elements. System elements are subject to various kinds of disturbances. In the example given, this may be a change in the filling factor of the pump cylinders due to changes in the parameters of the flushing liquid or the suction path.

Let's consider an example of closed-loop regulation with control of the result - flow rate Q. In Fig. Figure 1.1 shows a block diagram of the regulator (stabilizer) for the flow of flushing liquid Q. Here, the flow Q is controlled by a flow sensor DR. By adjuster Z by adjusting the voltage U ass the required flow rate Q is set. The motor shaft speed n (and therefore the flow rate Q) is determined by the load and voltage U G , which depends on the value of ∆U.

∆U = U ass - U os1 , (1.1)

where U os1 - voltage at the sensor output (U d ), proportional to the flow rate Q, and is called the feedback voltage. And this connection is in this case negative (conventionally indicated by painting the sector): decreases the value of U ass . When flow rate Q deviates from the specified value, U also changes os1 , which leads to a change in n and thus to the restoration of consumption Q.

Automatic maintenance a given law of change in process indicators using feedback is called automatic regulation. In the example considered, one indicator is Q. And it is called the controlled variable.

So, based on the example considered, we will assume that automatic device which carries out automatic regulation is called an automatic regulator.

In turn, the object controlled by the regulator is called a regulated object.

The combination of a regulated object and an automatic regulator constitutes an automatic control system (ACS).

By functional purpose automatic systems are divided into open-loop automatic control systems, closed-loop automatic control systems and automatic control systems.

Let's look at examples demonstrating the operation of the considered circuits.

1.Example. Filament current stabilizer for electronic tubes. The diagram demonstrates open-loop control.

Maintaining a constant filament current I N occurs without operator participation, i.e. no control is exercised.

Example Manual speed control ω electric motor shaft.

Rotational speed ω drive motor shaft D is a function of the voltage at the generator terminals U G , which at a constant armature rotation frequency ( ω VD = const) is determined by the current in the excitation winding of the generator. To regulate or maintain constant speed ω the operator monitors the readings of the voltmeter V, calibrated in the dimensions of rotational speed ω and, manually changing the current I with a rheostat P ovg in the excitation winding, achieves the required value ω.

Here we see a closed regulatory system. But such a manual control system has significant disadvantage: low control accuracy and undesirable presence of an operator. In addition, there are a number of disturbing influences: changing torque on the motor shaft M WITH , change in ambient temperature, brush wear electric machines etc., hence the inaccuracy of the regulatory system; The system is not applicable for fast processes.

The considered examples allow us to provide a basis for considering the issue of regulatory principles.

1.1.1 Regulatory principles

During the operation of the systems discussed above, the influence of external factors (disturbing influences) becomes obvious. The most simple solution To take into account each disturbing influence, it is necessary to install an appropriate sensor. However, this approach is not always feasible. As a way out of this situation, techniques are usually used according to which the deviation from a given value is first measured by installing a sensor, and then a correction is introduced based on the measured deviation (similar to the example with changing the position of the rheostat P slider).

The following basic principles of regulation are distinguished:

· by deviation;

· by indignation;

· compensation;

· combined.

Figure 1.4 demonstrates a circuit for automatic regulation (stabilization) of the engine shaft speed using one sensor for monitoring the deviation of the speed from the set value, which is a tachogenerator.

This scheme, in fact, is a transformation of a manual control scheme (Fig. 1.3) into an automatic control scheme (Fig. 1.4). Here the operator is replaced electrical system control and a system for influencing rheostat R. Rheostats R are included in the circuit 1 and P 2, a reversible motor RD, an electronic amplifier of the power unit, and a gearbox Red, which is mechanically connected to the rheostat motor R.

Let's consider the main regulatory elements (Fig. 1.4):

· the object of regulation, which is the engine, all other elements are included in the system regulator;

· indicator of the regulation process, which is angular velocity ω , i.e. a controlled quantity, which can be either constant or change in accordance with any law;

· a regulatory body, the role of which is played by the armature chain of the engine, by changing the position or state of which, the controlled variable can be changed;

· regulating influence - voltage in the armature circuit of the engine;

· setting value (impact) of the system - U ass ; that is, it is a quantity that is proportional or functionally related to the controlled quantity and serves to change the level of the latter; via U ass a specific value is specified ω.

If ∆U = U ass - U OS = 0, then a state of equilibrium will occur. U OS - this is the feedback voltage, which is proportional to the controlled value ω. When changing ω ( due to a change in moment M With resistance on the motor shaft) the feedback voltage U generated by the tachogenerator changes OS , the equilibrium is disturbed (∆U ≠ 0), which leads along the chain (EU - RD - Red - R - I ovg ) to a change in the voltage U generated by the generator G and to the restoration of the controlled variable ω.

In the considered scheme, the controlled variable is controlled in an active way, and the signal transmission circuit from the output to the input of the system is called the main feedback.

The principle of regulation, which is embedded in the diagram (Fig. 1.4), is called the principle of regulation by deviation. Systems that are built according to this principle always contain feedback. This means that they operate in a closed cycle.

By an automatic control system based on deviation, we mean a system during the operation of which the deviation of a controlled quantity from a given value is measured, and as a function of the deviation value, a certain regulatory action is generated that reduces this deviation to a minimum value.

Let us note and remember that deviation control systems must always contain the main negative feedback.

Another control principle, which is much less commonly used in automatic regulators, is the disturbance control principle or the compensation principle, as well as disturbance compensation.

In Fig. 1.5 demonstrates the generator circuit DC. This illustration explains the principle of disturbance control. Here the generator operates on a varying load R n . Voltage U is an adjustable variable. The emf of the generator is proportional to the excitation flux Φ V E G = k Φ V .

U = E - I n R A , (1.2)

E = U + I n R A =I n R n +I n R A =I n (R A + R n ) (1.3)

Let us assume that when the current I changes n voltage U = U O = const. Then the condition must be satisfied

E=U O + Δ E = U O +I n R A = k ( Φ in + ΔΦ V ). (1.4)

Means, Δ E will change due to

Φ V ·U O =k Φ in And ΔΦ V = (R A /k)·I n = c I n , (1.5)

those. change of controlled variable ΔΦ must be proportional to load current I n . This condition is met due to the compound winding, which provides additional excitation flux Φ extra , proportional to the disturbance load - current I N . Based on this, the main winding (main excitation flux F basic ) is intended to create an initial voltage U ABOUT. Meaning Δ E is determined by the compound winding. Both windings create a total magnetic flux F in.

As a result of changing the load current I N the total flow F changes in , and voltage U O constantly. This is an example of the implementation of the principle of compensation in regulation, when when measuring a load (disturbing effect) as a function of the measured value, a certain regulatory effect is generated, which allows the controlled value to remain constant. Systems operating on this compensation principle are open-loop systems that do not have feedback.

The main advantage of such systems is their speed. However, the system also has a number of disadvantages:

· due to the fact that the object has several disturbing influences and for compensation systems it is necessary to measure each disturbing influence separately and, as a function of it, develop a regulatory influence, which significantly complicates the system;

· the problem of measuring non-electrical disturbances;

· ambiguity and complexity of the dependence of the regulatory influence on the disturbing influence.

Due to these shortcomings, the systems considered are used much less frequently in comparison with systems that implement the principle of regulation by deviation.

The third principle of regulation is combined (a combination of the first two principles). Used even less frequently than the first two. The advantages and disadvantages are the same. The systems are quite complex and their study is not yet provided.

1.2 Classification of automatic control systems

According to the law of reproduction (change) of the controlled variable, closed control systems are divided into three types:

· stabilization systems,

· program control systems,

· tracking systems.

They differ from each other not fundamentally, but only in their mode of operation and design. They have a common theory and are studied using the same methods.

The stabilization system is a system for maintaining the constancy of the controlled variable. The systems discussed above relate to stabilization systems.

In program control systems, the controlled quantity must change according to a previously known program in time.

Tracking system. Here the controlled quantity changes according to an unknown arbitrary law. The law is determined by some external reference influence (arbitrarily).

Depending on the nature of the regulatory influence on the executive element, automatic control systems are divided into:

· continuous systems,

· pulse and

· relay regulation.

In continuous control systems, the signals at the output of all elements of the system are continuous functions of the signals at the input of the elements.

Pulse control systems are distinguished by the fact that in them, at certain intervals, the control loop is opened and closed by a special device. The control time is divided into pulses, during which processes proceed in the same way as in continuous control systems, and into intervals, during which the influence of the regulator on the system ceases. Such regulators are used to regulate slowly occurring processes (temperature regulation in industrial ovens, temperature and pressure in boilers).

In relay control systems, the control loop is opened by one of the system elements (relay element) depending on the external influence.

Depending on the results obtained during automatic regulation, two types of automatic regulation are distinguished:

· static and

· astatic.

Static is an automatic control in which the controlled quantity, under various constant external influences on the controlled object, takes on different values at the end of the transition process, depending on the magnitude of the external influence (for example, load).

In Fig. 1.6, and the water level regulator in the tank is presented. In the water level regulator, as the water flow rate q increases, the level decreases, a valve opens through the float and lever, inflow q 1 increases and vice versa.

The static control system has the following characteristic properties:

equilibrium of the system is possible at different values of the controlled variable;

Each value of the controlled quantity corresponds to a single specific position of the regulatory body.

To implement such a connection between the sensor and the actuator, the control loop must consist of so-called static links, in which, in a state of equilibrium, the output value uniquely depends on the input: . This is explained by the fact that the water flow q is equal to the inflow q1 at some strictly defined, specific level H. The flow will change, the level will change, the inflow will be equal to the flow - and equilibrium will come again.

A controller that performs static control is called a static controller.

To characterize the degree of dependence of the deviation of the controlled variable on the load in control theory, the concept of unevenness, or regulation staticism, is used.

Let the graph of the dependence of the steady-state values of the controlled variable x on the load q (control characteristic) have the form shown in Fig. 1.6, b (the control characteristic is given in specific coordinates for the water level regulator in the tank; below the coordinates are given in general view, for any static regulators). The maximum value of the controlled variable xmax corresponds to the idle speed of the object (no load); minimum value - rated load - qnom.

To determine the statism of regulation, we will use relative coordinates:

where φ is the relative value of the controlled variable;

The controlled variable itself;

Minimum value of the controlled variable (at nominal mode);

and qnom - basic values of quantities;

λ - relative load value.

Then the unevenness δ (or staticism) of the system in the general case is the partial derivative at a given point (or the relative slope of the control characteristic at this point):

If the control characteristic is linear, then droop will be a constant value for all load values. And it can be defined like this:

A static controller does not maintain a strictly constant value of the controlled variable, but with an error, which is called the static error of the system. Thus, regulation droop is a relative static error when the load changes from idle speed to nominal.

In some systems, a static error (even if only hundredths of a percent) is undesirable, then they move on to regulation in which it is equal to zero - to astatic regulation. The control characteristic of such a system is represented by a line parallel to the load axis.

Astatic control is automatic control in which, at various constant values of external influence on the object, the deviation of the controlled quantity from the set value at the end of the transition process becomes equal to zero.

In an astatic regulator of the water level H in the tank (Fig. 1.7), the float moves the rheostat slider in one direction or another depending on the change in level from the set value, thereby powering the motor that controls the position of the damper. The engine will be turned off when the water level reaches the set value.

The astatic control system has the following characteristic features:

equilibrium of the system occurs only at one value of the controlled variable, equal to the given value;

the regulatory body has the ability to occupy different positions with the same value of the controlled variable.

In real controllers, the first condition is met with some error. To fulfill the second condition, a so-called astatic link is introduced into the control loop. In the given example, an engine has the property that in the absence of voltage its shaft is motionless in any position, and in the presence of voltage it rotates continuously.

Depending on the source of energy received by the regulator, there are

· direct and

· indirect regulation.

In direct control systems, the energy for moving the control element is obtained from a sensor (for example, a static water level controller).

In indirect control systems, the energy for rearranging the control element is obtained from an external source (for example, an astatic water level regulator).

Automatic control systems with several controlled quantities (for example, steam pressure in the boiler, water supply to the boiler, fuel and air supply to the furnace) are divided into uncoupled and coupled control systems.

Unrelated regulation systems are those in which regulators designed to regulate various sizes, are not related to each other and can only interact through a common object of regulation. If in a system of unrelated regulation a change in one of the controlled quantities entails a change in other controlled quantities, then such a system is called dependent; and if it does not imply, then the system is called independent.

Coupled control systems are those in which regulators of various controlled quantities are connected to each other and in addition to the object of regulation.

A system of coupled regulation is called autonomous if the connections between its constituent regulators are such that a change in one of the regulated quantities during the regulation process does not cause a change in the remaining regulated quantities.

Closed-loop autonomous control systems that have only one (main) feedback are called single-loop. Automatic control systems that, in addition to one main feedback, have one or more main or local feedbacks are called multi-loop.

Depending on the type of characteristics of the elements that make up the systems, all systems are divided into:

· linear and

· nonlinear.

Linear systems are those that consist only of elements that have linear characteristics; transient processes in such elements are described by linear differential equations.

Nonlinear systems are those that have one or more elements with nonlinear characteristics; Transient processes in such systems are described by nonlinear differential equations.

When classified according to the type of energy used, all systems can be divided into:

· electrical,

· hydraulic,

· pneumatic,

· electrohydraulic,

· electro-pneumatic, etc.

Depending on the number of controlled quantities of the automatic control system (ACS):

one-dimensional,

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Basics of industrial process automation

Lecture Notes

Part 1. Theory of Automatic Control (TAC)

1. Basic terms and definitions of TAU.

1.1. Basic concepts.

Control systems for modern technological processes are characterized by a large number of technological parameters, the number of which can reach several thousand. To maintain the required operating mode, and ultimately the quality of the products, all these quantities must be maintained constant or changed according to a certain law.

Physical quantities that determine the progress of a technological process are called process parameters . For example, process parameters can be: temperature, pressure, flow, voltage, etc.

A technological process parameter that must be maintained constant or changed according to a certain law is called controlled variable or adjustable parameter .

The value of the controlled quantity at the considered moment in time is called instantaneous value .

The value of the controlled quantity obtained at the considered moment in time based on the data of some measuring device is called its measured value .

Example 1. Scheme of manual temperature control of the drying cabinet.

It is necessary to manually maintain the temperature in the drying cabinet at the T set level.

The human operator, depending on the readings of the mercury thermometer RT, turns on or off the heating element H using the switch P. 

Based on this example you can enter definitions:

Control object (object of regulation, OU) – a device whose required operating mode must be supported externally by specially organized control actions.

Control – formation of control actions that ensure the required operating mode of the op-amp.

Regulation – private view control, when the task is to ensure the constancy of any output value of the op-amp.

Automatic control – control carried out without direct human participation.

Input influence (X)– influence applied to the input of a system or device.

Output impact (Y) – the impact produced at the output of a system or device.

External influence – the impact of the external environment on the system.

The block diagram of the control system for example 1 is shown in Fig. 1.2.

Example 2. Scheme of automatic temperature control of the drying cabinet.

The circuit uses a mercury thermometer with RTK contacts. When the temperature rises to a given temperature, the contacts are closed by a column of mercury, the coil of the relay element RE is excited and the heater circuit H is opened by the contact RE. When the temperature drops, the contacts of the thermometer open, the relay is de-energized, resuming the supply of energy to the object (see Fig. 1.3). 

R
is. 1.3

Example 3. Temperature ASR circuit with measuring bridge.

When the temperature of the object is equal to the set one, the measuring bridge M (see Fig. 1.4) is balanced, no signal is received at the input of the electronic amplifier, and the system is in equilibrium. When the temperature deviates, the resistance of the thermistor R T changes and the balance of the bridge is disrupted. A voltage appears at the input of the EC, the phase of which depends on the sign of the temperature deviation from the set one. The voltage amplified in the EC is supplied to motor D, which moves the motor of the autotransformer AT in the appropriate direction. When the temperature reaches the set value, the bridge will be balanced and the engine will turn off.

(exercise)

The value of the set temperature value is set using resistor R set. 

Based on the examples described, it is possible to determine a typical block diagram of a single-circuit automatic control system (see Fig. 1.5). Accepted designations:

x - reference action (task), e = x - y - control error, u - control action, f - disturbing influence (disturbance).

Definitions:

Setting influence (the same as the input influence X) - the influence on the system that determines the required law of change of the controlled variable).

Control action (u) - the impact of the control device on the controlled object.

Control device (CD) - a device that influences the control object in order to ensure the required operating mode.

Disturbing influence (f) - an impact that tends to disrupt the required functional relationship between the reference impact and the controlled variable.

Control error (e = x - y) - the difference between the prescribed (x) and actual (y) values of the controlled variable.

Regulator (P) - a set of devices connected to a regulated object and providing automatic maintenance of the set value of its controlled variable or its automatic change according to a certain law.

Automatic control system (ASR) - an automatic system with a closed circuit of influence, in which control (u) is generated as a result of comparing the true value of y with a given value of x.

Additional contact in structural diagram The ASR directed from the output to the input of the considered section of the chain of influences is called feedback (FE). Feedback can be negative or positive.

The introduction of technical means into enterprises that allow automation of production processes is a basic condition efficient work. Diversity modern methods automation expands the range of their applications, while the costs of mechanization, as a rule, are justified by the end result in the form of an increase in the volume of manufactured products, as well as an increase in their quality.

Organizations that follow the path of technological progress occupy leading positions in the market and provide better quality working conditions and minimize the need for raw materials. For this reason, it is no longer possible to imagine large enterprises without implementing mechanization projects - exceptions apply only to small craft industries, where automation of production does not justify itself due to the fundamental choice in favor of manual production. But even in such cases, it is possible to partially turn on automation at some stages of production.

Automation Basics

In a broad sense, automation involves the creation of such conditions in production that will allow certain tasks for the manufacture and release of products to be performed without human intervention. In this case, the operator’s role may be to solve the most critical tasks. Depending on the goals set, automation of technological processes and production can be complete, partial or comprehensive. The choice of a specific model is determined by the complexity of the technical modernization of the enterprise due to automatic filling.

In plants and factories where full automation is implemented, usually mechanized and electronic systems management is transferred all the functionality to control production. This approach is most rational if operating modes do not imply changes. In partial form, automation is implemented at individual stages of production or during the mechanization of an autonomous technical component, without requiring the creation of a complex infrastructure for managing the entire process. A comprehensive level of production automation is usually implemented in certain areas - this could be a department, workshop, line, etc. In this case, the operator controls the system itself without affecting the direct work process.

Automated control systems

To begin with, it is important to note that such systems assume complete control over an enterprise, factory or plant. Their functions can extend to a specific piece of equipment, conveyor, workshop or production area. In this case, process automation systems receive and process information from the serviced object and, based on this data, have a corrective effect. For example, if the operation of a production complex does not meet the parameters of technological standards, the system will use special channels to change its operating modes according to the requirements.

Automation objects and their parameters

The main task when introducing production mechanization means is to maintain the quality parameters of the facility, which will ultimately affect the characteristics of the product. Today, experts try not to delve into the essence of the technical parameters of various objects, since theoretically the implementation of control systems is possible at any component of production. If we consider in this regard the basics of automation of technological processes, then the list of mechanization objects will include the same workshops, conveyors, all kinds of devices and installations. One can only compare the degree of complexity of implementing automation, which depends on the level and scale of the project.

Regarding the parameters with which automatic systems operate, we can distinguish input and output indicators. In the first case it is physical characteristics products, as well as the properties of the object itself. In the second, these are the direct quality indicators of the finished product.

Regulating technical means

Devices that provide regulation are used in automation systems in the form of special alarms. Depending on their purpose, they can monitor and control various process parameters. In particular, automation of technological processes and production can include alarms for temperature, pressure, flow characteristics, etc. Technically, devices can be implemented as scale-free devices with electrical contact elements at the output.

The operating principle of the control alarms is also different. If we consider the most common temperature devices, we can distinguish manometric, mercury, bimetallic and thermistor models. Structural design, as a rule, is determined by the operating principle, but operating conditions also have a significant influence on it. Depending on the direction of the enterprise’s work, automation of technological processes and production can be designed taking into account specific operating conditions. For this reason, control devices are developed with a focus on use in conditions high humidity, physical pressure or the effects of chemicals.

Programmable automation systems

The quality of management and control of production processes has noticeably increased against the background of the active supply of enterprises with computing devices and microprocessors. From the point of view of industrial needs, the capabilities of programmable technical means make it possible not only to provide effective management technological processes, but also to automate design, as well as conduct production tests and experiments.

Computer devices that are used in modern enterprises solve problems of regulation and control of technological processes in real time. Such production automation tools are called computing systems and operate on the principle of aggregation. The systems include unified functional blocks and modules, from which you can create various configurations and adapt the complex to work in certain conditions.

Units and mechanisms in automation systems

The direct execution of work operations is carried out by electrical, hydraulic and pneumatic devices. According to the principle of operation, the classification involves functional and portion mechanisms. Similar technologies are usually implemented in the food industry. Automation of production in this case involves the introduction of electrical and pneumatic mechanisms, the designs of which may include electric drives and regulatory bodies.

Electric motors in automation systems

The basis of actuators is often formed by electric motors. Depending on the type of control, they can be presented in non-contact and contact versions. Units that are controlled by relay contact devices can change the direction of movement of the working parts when manipulated by the operator, but the speed of operations remains unchanged. If automation and mechanization of technological processes using non-contact devices is assumed, then semiconductor amplifiers are used - electrical or magnetic.

Panels and control panels

To install equipment that should provide management and control of the production process at enterprises, special consoles and panels are installed. They house devices for automatic control and regulation, instrumentation, protective mechanisms, as well as various elements of communication infrastructure. By design, such a shield can be a metal cabinet or a flat panel on which automation equipment is installed.

The remote control, in turn, is the center for remote control- this is a kind of control room or operator area. It is important to note that the automation of technological processes and production should also provide access to maintenance by personnel. It is this function that is largely determined by consoles and panels that allow you to make calculations, evaluate production indicators and generally monitor the work process.

Automation systems design

The main document that serves as a guide for the technological modernization of production for the purpose of automation is the diagram. It displays the structure, parameters and characteristics of devices, which will later act as means of automatic mechanization. In the standard version, the diagram displays the following data:

level (scale) of automation at a specific enterprise;
determining the operating parameters of the facility, which must be provided with means of control and regulation;
control characteristics - full, remote, operator;
possibility of blocking actuators and units;
configuration of the location of technical equipment, including on consoles and panels.

Auxiliary automation tools

Despite the minor role, additional devices provide important control and management functions. Thanks to them, the same connection between actuators and a person is ensured. In terms of equipping with auxiliary devices, production automation may include push-button stations, control relays, various switches and command panels. There are many designs and varieties of these devices, but they are all focused on ergonomic and safe management key units at the facility.

Automation of production processes is the main direction along which production is currently moving throughout the world. Everything that was previously performed by man himself, his functions, not only physical, but also intellectual, are gradually transferred to technology, which itself carries out technological cycles and controls them. This is the general direction now modern technologies. The role of a person in many industries is already reduced to only a controller behind an automatic controller.

In general, the concept of “technological process control” is understood as a set of operations necessary to start, stop the process, as well as maintain or change in the required direction physical quantities (process indicators). Individual machines, units, devices, devices, complexes of machines and devices that carry out technological processes that need to be controlled are called control objects or controlled objects in automation. Managed objects are very diverse in their purpose.

Automation of technological processes– replacement of human physical labor spent on controlling mechanisms and machines with the work of special devices that ensure this control (regulation various parameters, obtaining the specified performance and quality of the product without human intervention).

Automation of production processes makes it possible to increase labor productivity many times over, increase its safety, environmental friendliness, improve product quality and make more efficient use of production resources, including human potential.

Any technological process is created and carried out to achieve a specific goal. Manufacturing the final product, or to obtain an intermediate result. Thus, the purpose of automated production can be sorting, transportation, and packaging of products. Automation of production can be complete, complex or partial.

Partial automation occurs when one operation or a separate production cycle is carried out automatically. At the same time, limited human participation in it is allowed. Most often, partial automation occurs when the process proceeds too quickly for the person himself to fully participate in it, while quite primitive mechanical devices, driven by electrical equipment, do an excellent job with it.

Partial automation, as a rule, is used on existing equipment and is an addition to it. However, it is most effective when included in common system automation from the very beginning - is immediately developed, manufactured and installed as its integral part.

Comprehensive automation should cover a separate large production area, this could be a separate workshop or power plant. In this case, the entire production operates in the mode of a single interconnected automated complex. Complex automation of production processes is not always advisable. Its field of application is modern highly developed production, which uses extremelyreliable equipment.

The breakdown of one of the machines or units immediately stops the entire production cycle. Such production must have self-regulation and self-organization, which is carried out according to a previously created program. In this case, a person takes part in the production process only as a permanent controller, monitoring the state of the entire system and its individual parts, and intervenes in production for start-up and when emergency situations arise, or when there is a threat of such an occurrence.

The highest level of automation of production processes – full automation. With it, the system itself carries out not only the production process, but also complete control over it, which is carried out by automatic control systems. Full automation is advisable in cost-effective, sustainable production with established technological processes with a constant operating mode.

All possible deviations from the norm must be previously foreseen, and systems for protecting against them must be developed. Full automation is also necessary for work that may threaten human life, his health, or is carried out in places inaccessible to him - under water, in an aggressive environment, in space.

Each system consists of components that perform specific functions. IN automated system The sensors take readings and transmit them to make a decision on how to control the system; the command is carried out by the drive. Most often this electrical equipment, since it is with the help electric current It makes more sense to execute commands.

It is necessary to distinguish between automated control systems and automatic ones. At automated control system the sensors transmit readings to the operator’s console, and he, having made a decision, transmits the command to the executive equipment. At automatic system– the signal is analyzed by electronic devices, and after making a decision, they give a command to the executing devices.

Human participation in automatic systems is still necessary, albeit as a controller. He has the ability to intervene in the technological process at any time, correct it or stop it.

So, the temperature sensor may fail and give incorrect readings. In this case, electronics will perceive its data as reliable without questioning it.

The human mind is many times greater than its capabilities electronic devices, although it is inferior to them in terms of response speed. The operator can understand that the sensor is faulty, assess the risks, and simply turn it off without interrupting the process. At the same time, he must be completely confident that this will not lead to an accident. Experience and intuition, which are inaccessible to machines, help him make a decision.

Such targeted intervention in automatic systems does not carry any serious risks if the decision is made by a professional. However, turning off all automation and switching the system to manual control mode is fraught with serious consequences due to the fact that a person cannot quickly respond to changing conditions.

A classic example is the accident at the Chernobyl nuclear power plant, which became the largest man-made disaster of the last century. It occurred precisely because the automatic mode was turned off, when already developed programs to prevent emergency situations could not influence the development of the situation in the station's reactor.

Automation of individual processes began in industry back in the nineteenth century. Suffice it to recall the automatic centrifugal regulator for steam engines Watt's designs. But only with the beginning of the industrial use of electricity did wider automation become possible, not of individual processes, but of entire technological cycles. This is due to the fact that previously mechanical force was transmitted to machines using transmissions and drives.

Centralized production of electricity and its use in industry, by and large, began only in the twentieth century - before the First World War, when each machine was equipped with its own electric motor. It was this circumstance that made it possible to mechanize not only the production process on the machine, but also to mechanize its control. This was the first step towards creating automatic machines. The first samples of which appeared in the early 1930s. Then the term “automated production” itself arose.

In Russia - then still in the USSR - the first steps in this direction were taken in the 30-40s of the last century. For the first time, automatic machines were used in the production of bearing parts. Then came the world's first fully automated production of pistons for tractor engines.

Technological cycles were combined into a single automated process, starting with the loading of raw materials and ending with the packaging of finished parts. This became possible thanks to wide application modern electrical equipment at that time, various relays, remote switches, and of course, drives.

And only the advent of the first electronic computers made it possible to reach a new level of automation. Now the technological process has ceased to be considered as simply a set of individual operations that must be performed in a certain sequence to obtain a result. Now the whole process has become one.

Currently, automatic control systems not only conduct the production process, but also control it and monitor the occurrence of abnormal and emergency situations. They start and stop technological equipment, monitor overloads, and work out actions in case of accidents.

Recently, automatic control systems have made it quite easy to rebuild equipment to produce new products. This is already a whole system, consisting of separate automatic multi-mode systems connected to a central computer, which links them into a single network and issues tasks for execution.

Each subsystem is a separate computer with its own software designed to perform its own tasks. It's already flexible production modules. They are called flexible because they can be reconfigured for other technological processes and thereby expand production and diversify it.

The pinnacle of automated production is. Automation has permeated production from top to bottom. The transport line for the delivery of raw materials for production operates automatically. Automated management and design. Human experience and intelligence are used only where electronics cannot replace it.