The material of the topic of the lecture contains the content of the following issues: the structure of the process control system; purpose, goals and functions of the process control system; examples of information and control process control systems; the main types of automated process control systems; composition of the process control system.

Structure of process control system. See also the content of lectures 1, 2,3.

When constructing the means of modern industrial automation(usually in the form of automated process control systems) a hierarchical information structure is used with the use of computing tools of different capacities at different levels. Approximate total modern structure The automated process control system is shown in Figure 14.1:

IP - measuring transducers (sensors),

IM - actuators,

PLC - programmable logic controller,

PrK - programmable (configurable) controller,

InP - intelligent measuring transducers,

InIM - intelligent actuators,

Modem - signal modulator / demodulator,

TO - technical support (hardware, hardware),

IO - information support (databases),

Software - software,

KO - communication support (serial port and software).

POpl - user software,

SOPR - manufacturer's software,

Ind is an indicator.

Figure 14.1 - A typical functional diagram of a modern process control system.

Currently, automated process control systems are usually implemented according to the schemes:

1. 1-level (local system) containing a PLC, or a monoblock customizable controller (MNC) providing indication and signaling of the state of a controlled or regulated TP on the front panel,

2. 2-tier (centralized system), including:

1. At the lower level, several PLCs with sensors and actuators connected to them,

2. At the top level - one (possibly several) operator (works) stations (automated workstations (AWS) of the operator).

Typically, a workstation or workstation is a computer in a special industrial design, with special software - a data collection and visualization system (SCADA system).

Typical functional diagram of a single-level APCS shown in figure 14.2

Figure 14.2 - A typical functional diagram of a single-level automatic control system for ACS.

The main functions of the elements:

1. Reception of discrete signals from converters of technological equipment,

2. Analog-to-digital conversion (ADC) of analog signals coming to the inputs from converters,

3. Scaling and digital filtering of data after ADC,

4. Processing of received data according to the program of operation,

5. Generation (in accordance with the program) of discrete control signals and their supply to actuating devices,

6. Digital-to-analog conversion (DAC) of output information data into output analog signals,

7. Supply of control signals to the relevant actuators,

8. Protection against the loss of performance due to the hang of the processor using a watchdog timer,

9. Maintaining performance during a temporary power outage (due to an uninterruptible power supply with a battery of sufficient capacity),

10. Monitoring the performance of sensors and the reliability of the measured values,

11. Indication of current and integral values ​​of the measured values,

12. Control signaling of the state of the controlled process,

13. Control light and symbolic signaling of the controller status,

14. Possibility of configuration (setting parameters) via a PC connected to a special port.

Converters (PR):

1. Converting the value of the measured value (temperature, pressure, displacement, etc.) into a continuous or pulsed (for PLC counting inputs) electrical signal.

Executive devices (ID):

1. Converting control electrical continuous or pulse signals into mechanical movement of actuators, electronic current control in power circuits, etc.

Matching device (if necessary):

1. Galvanic or other types of isolation between the PLC and actuators (ID),

2. Coordination of the permissible values ​​of the output current of the PLC control channels and the current required for the normal operation of the DUT.

If the number of channels of one PLC is insufficient, a distributed I/O scheme is used using other (managed, slave PLCs) or additional I/O controllers (modules).

Typical functional diagram of a single-level process control system with distributed input/output shown in figure 14.3 :

Figure 14.3 - Typical functional diagram of a single-level APCS with distributed I/O

A typical functional diagram of a 2-level process control system is shown in Figure 14.4.

Figure 14.4 - Typical functional diagram of a 2-level process control system

All PLCs and workstations are connected by an industrial information network that ensures continuous data exchange. Advantages: allows you to distribute tasks between the nodes of the system, increasing the reliability of its functioning.

Main functions of the lower level:

1. Collection, electrical filtering and ADC of signals from transducers (sensors);

2. Implementation of local process control systems in the scope of PLC functions of a single-level system;

3. Implementation of emergency and warning signaling;

4. Organization of a system of protections and blockings;

5. Exchange of current data from the upper-level PC through the industrial network at the request of the PC.

Main top-level features:

1. Visualization of the state of the technological process;

2. Current registration of the characteristics of the technological process;

3. Operational analysis of the state of equipment and technological process;

4. Registration of operator's actions, including in case of emergency messages;

5. Archiving and long-term storage values ​​of technological process protocols;

6. Implementation of algorithms of the “advisor system”;

7. Supervisory management;

8.Storage and maintenance of databases:

process parameters,

Critical equipment parameters,

Signs of emergency conditions technological process,

The list of operators allowed to work with the system (their passwords).

Thus, the lower level implements the algorithms management equipment, the upper one - the solution of strategic issues of functioning. For example, the decision to turn the pump on or off is made at the top level, while the supply of all necessary control signals, checking the status of the pump, and the implementation of the blocking mechanism are performed at the lower level.

The hierarchical structure of the process control system implies:

1. The flow of commands is directed from the top level to the bottom,

2. The bottom responds to the top according to his requests.

This ensures predictable behavior of the PLC in the event of a failure of the upper layer or industrial network, since such failures are perceived by the lower layer as the absence of new commands and requests.

When configuring the PLC, it is set: until what time after receiving the last request, the PLC continues to function, maintaining the last set mode, after which it switches to the mode of operation required for this emergency.

For example, the structure of the organization of a process control system for some concrete production at concrete mixing plants can be divided into two main levels according to the logic of construction:

The lower level is the level of task implementation based on industrial controllers (PLC);

The upper level is the level of implementation of the task of visualizing the processes occurring during the production of concrete at the BSU (SCADA).

At the lower level, the system solves the following main tasks:

Collection of primary information from BSU executive units;

Analysis of the collected information;

Development of the logic of the technological process in the production of concrete, taking into account all modern requirements;

Issuance of control actions on executive devices.

At the top level, the system solves other tasks:

Visualization of the main technological parameters with BSU (state of executive bodies, current consumption of the mixer, weight of dosed materials, etc.);

Archiving of all parameters of the concrete production process;

Issuing commands to influence executive bodies BSU;

Issuing commands to change the parameters of external influences;

Development and storage of concrete mix formulations.

Purpose of process control system. The process control system is designed to develop and implement control actions on a technological control object.

Technological control object (APCS) is a set of technological equipment and implemented on it according to the relevant instructions or regulations of the technological process for the production of products, semi-products, products or energy,

Technological control objects include:

Technological units and installations (groups of machines) that implement an independent technological process;

Separate industries (workshops, sections), if the management of this production is mainly of a technological nature, that is, it consists in the implementation of rational modes of operation of interconnected technological equipment (aggregates, sections).

The jointly functioning TOU and the process control system that controls them form an automated technological complex (ATC). In mechanical engineering and other discrete industries, flexible production systems (FPS) act as ATCs.

The terms APCS, TOU and ATK should be used only in the given combinations. The totality of other control systems with their control of process equipment is not ATC. The control system in other cases (not in the ATK) is not a process control system, etc. A process control system is an organizational and technical system for managing an object as a whole in accordance with the accepted management criterion (criteria), in which the collection and processing of the necessary information is carried out using computer technology.

The above wording emphasizes:

Firstly, the use of modern computer technology in the process control system;

Secondly, the role of a person in the system as a subject of labor, taking a meaningful part in the development of management decisions;

Thirdly, that the process control system is a system that processes technological and technical and economic information;

Fourthly, that the purpose of the operation of the process control system is to optimize the operation of the technological control object in accordance with the accepted control criterion (criteria) by appropriately selecting control actions.

Control criterion in process control systems - this is a ratio that characterizes the degree of achievement of management goals (the quality of the functioning of the technological control object as a whole) and takes on different numerical values ​​depending on the control actions used. It follows that the criterion is usually technical and economic (for example, the cost of the output product for a given quality, the productivity of the TOU for a given quality of the output product, etc.) or technical indicator(process parameter, characteristics of the output product).

If the TOU is controlled by the process control system, all the operating personnel of the TOU involved in the management and all controls provided for by the documentation for the process control system and interacting when managing the TOU are part of the system, regardless of which way (new construction or modernization of the control system) was created ATK.

Process control system is created by capital construction, because regardless of the scope of supply, for its commissioning, it is necessary to carry out construction, installation and commissioning work at the facility.

APCS as a component of the overall control system of an industrial enterprise is designed to purposefully conduct technological processes and provide related and higher-level control systems with operational and reliable technical and economic information. APCS created for the objects of the main and (or) auxiliary production, represent the lower level of automated control systems in the enterprise.

APCS can be used to manage individual industries that include interconnected TOUs, including those managed by their own APCS at the lower level.

For objects with a discrete nature of production as part of flexible production systems automated systems may be included technological preparation production (or their respective subsystems) and computer-aided design technology (CAD technology).

The organization of interaction between the process control system and higher levels of management is determined by the availability of industrial enterprise automated system enterprise management (ASUP) and automated systems of operational dispatch control (ASODU).

If they are available, the process control system together with them form an integrated automated control system (IACS). In this case, the APCS receives from the relevant subsystems of the APCS or enterprise management services directly or through the OSODU tasks and restrictions (the range of products or products to be released, production volume, technical and economic indicators, characterize the quality of the ATK functioning, information about the availability of resources) and provides training and transfer to these systems of the technical and economic information necessary for their operation, in particular, on the results of the work of the ATC, the main indicators of products, the operational need for resources, the state of the ATC (equipment condition, the course of the technological process, its technical and economic indicators, etc.) .),

If the enterprise has automated systems for technical and technological preparation of production, the necessary interaction of the process control system with these systems should be ensured. At the same time, the process control systems will receive from them the technical, technological and other information necessary to ensure the specified conduct of technological processes, and send the actual operational information necessary for their operation to these systems.

When creating an integrated product quality management system at an enterprise, automated process control systems act as its executive subsystems that ensure the specified quality of TOU products and the preparation of operational factual information about the progress of technological processes (statistical control, etc.)

Goals and functions of process control systems.

When creating an automated process control system, specific goals for the functioning of the system and its purpose in overall structure enterprise management.

Examples of such goals are:

Saving fuel, raw materials, materials and other production resources;

Ensuring the safety of the operation of the facility;

Improving the quality of the output product or ensuring the specified values ​​of the parameters of the output products (products);

Reducing the cost of living labor;

Achieving optimal loading (use) of equipment;

Optimization of operating modes of technological equipment (including processing routes in discrete industries), etc.

Achievement of the set goals is carried out by the system through the implementation of a set of its functions.

The APCS function is a set of system actions that ensure the achievement of a particular control goal.

At the same time, the set of system actions is understood as the sequence of operations and procedures described in the operational documentation, performed by the elements of the system for its implementation.

The particular purpose of the operation of the process control system is the purpose of the operation or the result of its decomposition, for which it is possible to determine the full set of actions of the elements of the system, sufficient to achieve this goal.

The functions of the process control system according to the direction of actions (on-value of the function) are divided into main and auxiliary, and in terms of the content of these actions - on managerial and informational.

To main(consumer) functions of the process control system include functions aimed at achieving the goals of the system functioning, performing control actions on the TOU and (or) exchanging information with related control systems. Usually, they also include information functions that provide the operational personnel of the ATK with the information they need to control the technological process of production.

To auxiliary APCS functions include functions aimed at achieving the required quality of functioning (reliability, accuracy, etc.) of the system that implements control and management of its operation.

To manager APCS functions include functions, the content of each of which is the development and implementation of control actions on the corresponding control object - TOU or its part for the main functions and on the APCS or its part for auxiliary ones.

For example:

Basic control functions;

Regulation (stabilization) of individual technological variables;

Single-cycle logical control of operations or devices (protection);

Software logical control of technological devices;

Optimal control of TOU;

Adaptive control of TOU, etc.;

Auxiliary control functions;

Reconfiguration of the computer complex (network) APCS;

Emergency shutdown of APCS equipment;

Switching the technical means of the process control system to an emergency power source, etc.

To informational APCS functions include functions, the content of each of which is to receive and convert information about the state of the TOU or APCS and its presentation to related systems or operational personnel of the ATC.

For example, the main information functions:

Control and measurement of technological parameters;

Indirect measurement of process parameters (internal variables, technical economic indicators);

Preparation and transfer of information to snow management systems, etc.;

Auxiliary information functions:

Control of the condition of the APCS equipment;

Determination of indicators characterizing the quality of the functioning of the process control system or its parts (in particular, the operating personnel of the process control system), etc.

The main types of process control systems There are two modes of implementation of system functions: automated and auto- depending on the degree of participation of people in the performance of these functions. For control functions, the automated mode is characterized by human participation in the development (making) of decisions and their implementation.

In this case, the following options are distinguished:

- « manual» a mode in which the complex of technical means provides the operating personnel with control and measuring information about the state of the TOU, and the selection and implementation of control actions remotely or locally is carried out by a human operator;

Mode " adviser”, in which a set of technical means develops management recommendations, and the decision on their use is implemented by the operational staff;

- « interactive mode”, when operational personnel have the opportunity to correct the statement and conditions of the problem solved by the complex of technical means of the system when developing recommendations for managing the facility;

- « auto mode”, in which the control function is carried out automatically (without human intervention).

At the same time, they distinguish:

Mode indirect control when computer facilities change setpoints and/or settings local systems automatic control (regulation) ( supervisory or cascade control);

Mode direct(direct) digital control ( NCU), when the control computing device directly affects the actuators.

The day of information functions, the automated implementation mode provides for the participation of people in operations to receive and process information. In automatic mode, all the necessary information processing procedures are implemented without human participation.

Let us consider in more detail the control schemes in the process control system.

Acquisition control

After the identification stage, it is necessary to choose a TP control scheme, which, as a rule, is built taking into account the application of control principles that determine the operating mode of the process control system. The simplest and historically the first appeared TP control scheme in acquisition mode. In this case, the ACS is connected to the process in a manner chosen by the process engineer (Figure 14.5).

The variables of interest to the process engineer are converted to digital form, perceived by the input system and placed in memory PPK (computer). The values ​​in this step are digital representations of the voltage generated by the sensors. These quantities are converted into engineering units according to the appropriate formulas. For example, to calculate the temperature measured using a thermocouple, the formula T \u003d A * U 2 + B * U + C can be used, where U is the voltage from the thermocouple output; A, B and C are coefficients.

The calculation results are recorded by the APCS output devices for subsequent use by the process engineer. main goal data collection is the study of TA in various conditions. As a result, the process engineer gets the opportunity to build and (or) refine the mathematical model of the technological process that needs to be controlled. Data collection does not have a direct impact on TP, it has found a cautious approach to the introduction of management methods based on the use of computers. However, even in the most complex TP control schemes, the data collection system for the purposes of analysis and refinement of the TP model is used as one of the mandatory control subschemes.

Figure 14.5 - Data acquisition system

This mode assumes that the control panel as part of the process control system operates in the rhythm of the TP in an open loop (in real time), i.e. the outputs of the process control system are not connected with the bodies that control the technological process. Control actions are actually carried out by the process operator receiving instructions from the control panel (Figure 14.6).

Figure 14.6 - Process control system in operator advisor mode

All necessary control actions are calculated by the PPC in accordance with the TP model, the calculation results are presented to the operator in hard copy(or as messages on the display). The operator controls the process by changing the settings of the regulators. Regulators are means of maintaining the optimal control of the TP, and the operator plays the role of a follower and control link. The process control system plays the role of a device that accurately and continuously guides the operator in his efforts to optimize the technological process.

The scheme of the adviser system coincides with the scheme of the information collection and processing system.

The ways of organizing the functioning of the information-advising system are as follows:

The calculation of control actions is carried out when the parameters of the controlled process deviate from the specified technological modes, which are initiated by the dispatcher program containing the subroutine for analyzing the state of the controlled process;

The calculation of control actions is initiated by the operator in the form of a request, when the operator has the opportunity to enter additional data necessary for the calculation, which cannot be obtained by measuring the parameters of the controlled process or kept in the system as reference.

These systems are used in cases where a careful approach to decisions generated by formal methods is required.

This is due to the uncertainty in the mathematical description of the controlled process:

The mathematical model does not fully describe the technological (production) process, since it takes into account only a part of the control and manageable parameters;

The mathematical model is adequate to the controlled process only in a narrow range of technological parameters;

Management criteria are of a qualitative nature and vary significantly depending on a large number of external factors.

The uncertainty of the description may be due to insufficient knowledge of the technological process, or the implementation of an adequate model will require the use of expensive PPC.

With a large variety and volume of additional data, the communication between the operator and the control panel is built in the form of a dialogue. For example, alternative points are included in the process mode calculation algorithm, after which the calculation process can continue according to one of several alternative options. If the logic of the algorithm leads the calculation process to a certain point, then the calculation is interrupted and a message request is sent to the operator additional information, on the basis of which one of the alternative ways to continue the calculation is selected. The PPC plays a passive role in this case, associated with the processing of a large amount of information and its presentation in a compact form, and the decision-making function is assigned to the operator.

The main disadvantage of this control scheme is the constant presence of a person in the control circuit. With a large number of input and output variables, such a control scheme cannot be used due to the limited psychophysical capabilities of a person. However, this type of management also has advantages. It satisfies the requirements of a cautious approach to new management methods. The advisor mode provides a good opportunity to test new TP models; an engineer-technologist, "subtly feeling" the process, can act as an operator. He will surely detect the wrong combination of settings, which can be issued by an incompletely debugged APCS program. In addition, the process control system can monitor the occurrence of emergencies, so that the operator has the opportunity to pay more attention to working with settings, while the process control system monitors a greater number of emergencies than the operator.

supervisory management.

In this scheme, the process control system is used in a closed loop, i.e. settings for regulators are set directly by the system (Figure 14.7).

Figure 14.7 - Scheme of supervisory control

The task of the supervisory control mode is to maintain the TP near the optimal operating point by promptly influencing it. This is one of the main advantages of this mode. The operation of the input part of the system and the calculation of control actions differ little from the operation of the control system in the adviser mode. However, once the setpoints have been calculated, they are converted into values ​​that can be used to change the settings of the controllers.

If the regulators perceive voltages, then the quantities generated by the computer must be converted into binary codes, which, using a digital-to-analog converter, are converted into voltages of the appropriate level and sign. TP optimization in this mode is performed periodically, for example. once a day. New coefficients must be introduced into the control loop equations. This is carried out by the operator through the keyboard, or by reading the results of new calculations performed on a computer of a higher level. After that, the process control system is able to work without outside intervention for a long time.

Examples of process control systems in supervisory mode:

1. Management of the automated transport and storage system. The computer issues the addresses of the rack cells, and the system of local automation of stacker cranes works out their movement in accordance with these addresses.

2. Management of melting furnaces. The computer generates the values ​​of the electric mode settings, and the local automation controls the transformer switches according to the computer commands.

3. CNC machine control via interpolator.

Thus, supervisory control systems operating in the supervisory control mode (supervisor - a control program or a set of programs, a dispatcher program), is designed to organize a multi-program operating mode of the control panel and is a two-level hierarchical system with broad capabilities and increased reliability. The control program determines the order in which programs and subroutines are executed and manages the loading of PPK devices.

In the supervisory control system, part of the parameters of the controlled process and logical-command control is controlled by local automatic controllers (AR) and PPC, processing the measurement information, calculates and sets the optimal settings for these controllers. The rest of the parameters are controlled by the control panel in direct digital control mode.

The input information is the values ​​of some controlled parameters measured by sensors Du of local regulators; controlled parameters of the state of the controlled process, measured by sensors Dk. The lower level, directly related to the technological process, forms local regulators of individual technological parameters. According to the data coming from the sensors Dn and Dk through the communication device with the object, the control panel generates setpoint values ​​in the form of signals that come directly to the inputs of automatic control systems.

Direct digital control.

In the NCU, the signals used to actuate the control bodies come directly from the process control system, and the regulators are generally excluded from the system. The NCU concept, if necessary, allows replacing the standard regulatory laws with the so-called. optimal with a given structure and algorithm. For example, an optimal performance algorithm can be implemented, etc.

The process control system calculates real impacts and transmits the corresponding signals directly to the control bodies. The NCC scheme is shown in Figure 14.8.

Figure 14.8 - Scheme of direct digital control (NCD)

The settings are entered into the automated control system by the operator or a computer that performs calculations to optimize the process. In the presence of the NCU system, the operator must be able to change the settings, control some selected variables, vary the ranges of permissible change in the measured variables, change the settings, and generally must have access to the control program.

One of the main advantages of the NCU mode is the ability to change control algorithms for circuits by simply making changes to the stored program. The most obvious drawback of the NCU is manifested when the computer fails.

So the systems direct digital control(PTsU) or direct digital control (NTsU, DDC). The control panel directly generates the optimal control actions and, using the appropriate converters, transmits control commands to the actuators.

Direct digital control mode allows you to:

Exclude local regulators with setpoint;

apply more effective principles regulation and management and choose their optimal variant;

Implement optimizing functions and adaptation to change external environment and variable parameters of the control object;

Reduce maintenance costs and unify controls and controls.

This control principle is used in CNC machines. The operator must be able to change the settings, control the output parameters of the process, vary the ranges of permissible change of variables, change the settings, have access to the control program in such systems, the implementation of the start and stop modes of processes is simplified, switching from manual control to automatic, switching operations of actuators. The main disadvantage of such systems is that the reliability of the entire complex is determined by the reliability of the communication devices with the object and the control panel, and if the object fails, it loses control, which leads to an accident. The way out of this situation is the organization of computer redundancy, the replacement of one computer with a system of machines, etc.

The composition of the process control system.

The performance of the functions of the process control system is achieved through the interaction of its following components:

Technical support (TO),

Software (SW),

Information support (IS),

Organizational support (OO),

Operational personnel (OP).

These five components and form the composition of the process control system. Sometimes other types of support are also considered, for example, linguistic, mathematical, algorithmic, but they are considered as software components, etc.

Technical support The process control system is a complete set of technical means (including computer equipment) sufficient for the operation of the process control system and the performance of all its functions by the system. Note. Regulatory bodies are not included in the TO APCS.

The complex of selected technical means should provide such a system of measurements under the conditions of operation of the automated process control system, which, in turn, provide the necessary accuracy, speed, sensitivity and reliability in accordance with the specified metrological, operational and economic characteristics. Technical means can be grouped according to operational characteristics, control functions, information characteristics, and structural similarity. The most convenient is the classification of technical means according to information characteristics.

In connection with the above, the complex of technical means should contain:

1) means of obtaining information about the state of the control object and means of input to the system (input converters, sensors) that convert input information into standard signals and codes;

2) means of intermediate information conversion, providing the relationship between devices with different signals;

3) output converters, information output and control means that convert machine information into various forms necessary for process control;

4) means of generating and transmitting information that ensure the movement of information in space;

5) means of fixing information, ensuring the movement of information in time;

6) means of information processing;

7) means of local regulation and management;

8) computer facilities;

9) means of presenting information to operational personnel;

10) executive devices;

11) means of transmitting information to adjacent automated control systems and automated control systems of other levels;

12) devices, devices for adjusting and checking the system performance;

13) documentation technology, including the means of creating and destroying documents;

14) office and archival equipment;

15) auxiliary equipment;

16) materials and tools.

Auxiliary technical means ensure the implementation of secondary management processes: copying, printing, processing correspondence, creating conditions for the normal work of managerial personnel, maintaining technical equipment in good condition and their functioning. The creation of standard automated process control systems is currently impossible due to a significant discrepancy organizational systems enterprise management.

The technical means of automated process control systems must comply with the requirements of GOSTs, which are aimed at ensuring various compatibility of the automation object.

These requirements are divided into groups:

1. Informational. Provide information compatibility of technical means among themselves and with service personnel.

2. Organizational. The process control structure, control technology, technical means must correspond to each other before and after the introduction of automated process control systems, for which it is necessary to provide:

Correspondence of the structures of the CTS - the structure of the facility management;

Automated execution of basic functions, information extraction, its transmission, processing, data output;

Possibility of modification of KTS;

Possibility of creation of organizational systems of control of work of KTS;

Ability to create personnel control systems.

3. Mathematical . Smoothing out inconsistencies in the work of technical means with information can be done with the help of programs for transcoding, translation, re-layouts.

This causes the following requirements for mathematical software:

Quick solution of the main tasks of automated process control systems;

Simplification of communication of personnel with KTS;

Possibility of information docking of various technical means.

4. Technical requirements:

Necessary productivity for timely solution of APCS tasks;

Adaptability to the conditions of the external environment of the enterprise;

Reliability and maintainability;

The use of unified, mass-produced blocks;

Ease of operation and maintenance;

Technical compatibility of funds based on a common elemental and design base;

Ergonomics, technical aesthetics requirements.

5. Economic requirements for technical means:

Minimum capital investment for the creation of KTS;

Minimum production area for the placement of CTS;

Minimal costs for auxiliary equipment.

6. Reliability APCS. When considering the technical support, the issue of the reliability of the automated process control system is also considered.

At the same time, it is necessary to conduct research on automated process control systems, highlighting the following points:

1) complexity (a large number of different technical means and personnel);

2) multifunctionality;

3) multidirectional use of elements in the system;

4) multiplicity of failure modes (causes, consequences);

5) the relationship between reliability and economic efficiency;

6) dependence of reliability on technical operation;

7) dependence of reliability on CTS and the structure of algorithms;

8) the impact of personnel on reliability.

The level of operational reliability of APCS is determined by such factors as:

The composition and structure of the technical means used;

Modes, maintenance and recovery options;

Operating conditions of the system and its individual components;

The APCS software is a set of programs and operational software documentation necessary for the implementation of the functions of an automated process control system of a given mode of operation of the APCS hardware complex.

The APCS software is subdivided into general software (OPS) and special software (SPO).

To general APCS software includes that part software, which is supplied complete with computer equipment or purchased ready-made in specialized funds of algorithms and programs. The HPO APCS includes programs used for developing programs, linking software, organizing the operation of a computer complex and other utility and standard programs (for example, organizing programs, broadcasting programs, libraries of standard programs, etc.). HIF APCS is manufactured and supplied in the form of products for industrial purposes by manufacturers of VT means (see clause 1.4.7).

To special APCS software refers to that part of the software that is developed when creating a specific system (systems) and includes programs for implementing the main (control and information) and auxiliary ones (ensuring the specified functioning of the CTS system, checking the correctness of information input, monitoring operation of the CTS system, etc.) of the functions of the process control system. Special software for process control systems is developed on the basis of and using software. Individual programs or open source software for process control systems as a whole can be produced and delivered in the form of software tools as products for industrial and technical purposes.

The software includes general software supplied with computer equipment, including organizing programs, dispatcher programs, broadcast programs, operating systems, libraries of standard programs, as well as special software that implements the functions of a particular system, ensures the functioning of the CTS, including by hardware.

Mathematical, algorithmic support. As you know, a model is an image of the object of study, displaying the essential properties, characteristics, parameters, relationships of the object. One of the methods for studying processes or phenomena in automated process control systems is the method of mathematical modeling, i.e. by constructing their mathematical models and analyzing these models. A variety of mathematical modeling is simulation modeling, which uses direct substitution of numbers that simulate external influences, parameters and process variables using UVC. To conduct simulation studies, it is necessary to develop an algorithm.

Algorithms used in APCS are characterized by the following features:

Temporal connection of the algorithm with the controlled process;

Storage of work programs in random access memory UVK for access to them at any time;

Excess specific gravity logical operations;

Separation of algorithms into functional parts;

Implementation of UVC algorithms in time-sharing mode.

Taking into account the time factor in control algorithms is reduced to the need to fix the time of receiving information into the system, the time of issuing messages by the operator to form control actions, predict the state of the control object. It is necessary to ensure timely processing of signals from the UVC associated with the controlled object. This is achieved by compiling the most efficient in terms of speed algorithms implemented on high-speed UVC.

From the second feature of the APCS algorithms, there are stringent requirements for the amount of memory required to implement the algorithm, for the algorithm's connectivity.

The third feature of the algorithms is due to the fact that technological processes are controlled on the basis of decisions made based on the results of comparing various events, comparing the values ​​of object parameters, checking the fulfillment of various conditions and restrictions.

The use of the fourth feature of the APCS algorithms allows the developer to formulate several tasks of the system, and then combine the developed algorithms of these tasks into single system. The degree of interrelation of the tasks of the APCS can be different and depends on the specific control object.

To take into account the fifth feature of control algorithms, it is necessary to develop real-time operating systems and plan the sequence of loading modules that implement the algorithms of APCS tasks, their execution depending on priorities.

At the stage of development of automated process control systems, measuring information systems are created that provide complete and timely control of the operating mode of the units, which allow analyzing the course of the technological process and speeding up the solution of optimal control problems.

The functions of centralized control systems are reduced to solving the following tasks:

Determination of current and predicted values ​​of quantities;

Determination of indicators depending on a number of measured values;

Detection of events that are violations and malfunctions in production.

The general model of the problem in assessing the current values ​​of the measured values ​​and the TEC calculated from them in the centralized control system can be represented as follows: a set of values ​​and indicators that need to be determined in the control object is specified, the required accuracy of their assessment is indicated, there is a set of sensors that are installed on automated object. Then the general task of estimating the value of a single quantity is formulated as follows: for each individual quantity, it is required to find a group of sensors, the frequency of their polling and an algorithm for processing the signals received from them, as a result of which the value of this quantity is determined with a given accuracy.

To solve problems in the conditions of automated process control systems, such mathematical methods as linear programming, dynamic programming, optimization methods, convex programming, combinatorial programming, nonlinear programming are used. Methods for constructing a mathematical description of an object are the Monte Carlo method, mathematical statistics, experiment planning theory, queuing theory, graph theory, systems of algebraic and differential equations.

The information support of the process control system includes: a list and characteristics of signals characterizing the state of the ATC:

Description of the principles (rules) of classification and coding of information and a list of classification groups,

Descriptions of information arrays, forms of documents for video frames used in the system,

Regulatory reference (conditionally permanent) information used in the operation of the system.

Part organizational support APCS includes a description of the APCS (functional, technical and organizational structure of the system) and instructions for operational personnel, necessary and sufficient for its functioning as part of the ATC.

Organizational support includes a description of the functional, technical, organizational structures of the system, instructions and regulations for operational personnel on the work of automated process control systems. It contains a set of rules, regulations that ensure the required interaction of operational personnel between themselves and a set of tools.

Thus, the organizational structure of management is the relationship between people involved in the operation of the facility. The personnel involved in operational management maintains the technological process within the specified standards, ensures the implementation production plan, controls the operation of technological equipment, monitors the conditions for safe process management.

The operating personnel of the APCS ensures the correct functioning of the CTS of the APCS, keeps records and reports. The automated process control system receives production tasks from a higher level of management, the criteria for the implementation of these tasks, transfers to higher levels of management information about the fulfillment of tasks, quantitative and qualitative indicators of products and the functioning of an automated technological complex.

To analyze the organizational structure and determine the optimal construction of internal relationships, methods of group dynamics are used. In this case, the methods and techniques of social psychology are usually used.

The conducted studies made it possible to formulate the requirements necessary for organizing a group of operational technological personnel:

All production information should be transmitted only through the manager;

One subordinate should have no more than one immediate supervisor;

In the production cycle, only subordinates of one leader interact with each other in information.

Subdivisions Maintenance perform work at all stages of the creation of automated process control systems (design, implementation, operation), their main functions are:

Ensuring the operation of systems in accordance with the rules and requirements of technical documentation;

Ensuring current and scheduled repair of technical means of automated process control systems;

Carrying out, together with the developers, tests of automated process control systems;

Conducting research to determine the economic efficiency of the system;

Development and implementation of measures for the further development of the system;

Advanced training of employees of the APCS service, study and generalization of operating experience. To perform the functions, the technologist-operator must be provided with technical and software tools that provide, depending on the characteristics of the technological process, the required sets of the following information messages:

Indication of measured parameter values ​​on call;

Indication and change of the set limits of control of process parameters;

Sound alarm and indication of parameter deviations beyond the regulatory limits;

Sound alarm and indication of deviations in the rate of change of parameters from the set values;

Displaying the state of the technological process and equipment on the scheme of the control object;

Registration of trends in parameter changes;

Operational registration of violations of the technological process and operator actions.

Information support (IS) includes a coding system for technological and technical and economic information, reference and operational information, contains a description of all signals and codes used to communicate technical means. The codes used must include a minimum number of characters, have a logical structure and meet other coding requirements. Forms of output documents and submissions of information should not cause difficulties in their use.

When developing and implementing an IS APCS system, it is necessary to take into account the principles of organizing the process control, which correspond to the following stages.

1) Definition of APCS subsystems and types management decisions for which it is necessary to provide scientific and technical information. The results of this stage are used to determine the optimal structure of information arrays, to identify the characteristics of the expected flow of requests.

2) Definition of the main groups of information consumers. Consumers of information are classified depending on their participation in the preparation and adoption of management decisions related to the organization of the technological process. The accumulation of information is carried out taking into account the types of tasks solved in the process management. The consumer can obtain information on related technological areas, and conditions are also created for the redistribution of information when needs change.

3) Study of information needs.

4) The study of the flows of scientific and technical information necessary for managing processes is based on the results of the analysis of management tasks. Along with the flow of documentary information, facts are analyzed that reflect the experience of this and similar enterprises.

5) Development of information retrieval systems for process control.

Automated systems are characterized by information processing processes - transformation, transmission, storage, perception. When managing a technological process, information is transmitted and the input information is processed by the control system into output information. At the same time, control and regulation are necessary, which consist in comparing information on the results of the previous stage of activity with information corresponding to the conditions for achieving the goal, in assessing the mismatch between them and developing a corrective output signal. The mismatch is caused by internal and external disturbing influences of a random nature. The process of information transfer presupposes the existence of a source of information and a receiver.

Documentation of information is necessary to ensure human participation in the management of the technological process. Subsequent analyzes require the accumulation of statistical initial data by recording the states and values ​​of process parameters over time. On the basis of this, compliance with the technological process, product quality is checked, the actions of personnel in emergency situations are monitored, and directions for improving the process are searched.

When developing information support for automated process control systems related to documentation and registration, it is necessary:

Determine the type of registered parameters, place and form of registration;

Select the registration time factor;

Minimize the number of recorded parameters for reasons of necessity and sufficiency for operational actions and analysis;

Unify document formats, their structure;

Enter special details;

Solve the issues of classification of documents and routes of their movement;

Determine the amount of information in the documents, establish the place and terms of storage of documents.

The information flows in the communication channels of the automated process control system must be transmitted by the system from necessary quality information from the place of its formation to the place of its reception and use.

To do this, the following requirements must be met:

Timely delivery of information;

Transmission fidelity - no distortion, loss;

Reliability of functioning;

Unity of time in the system;

Possibility of technical implementation;

Ensuring the economic acceptability of information requirements. In addition, the system must provide:

Regulation of information flows;

Possibility of external relations;

Possibility of expanding the process control system;

Convenience of human participation in the analysis and management of the process.

The main characteristics of the information flow include:

Control object (source of information);

The purpose of the information;

Information format;

Volumetric-temporal characteristics of the flow;

Frequency of occurrence of information;

The object that uses the information.

If necessary, the flow characteristics are detailed by indicating:

Type of information;

Names of the controlled parameter;

Range of parameter change in time;

Numbers of parameters with the same names on the object;

Conditions for displaying information;

The speed of information generation.

The main information characteristics of the communication channel include:

The location of the beginning and end of the communication channel;

The form of the transmitted information;

Transmission channel structure - sensor, encoder, modulator, communication line, demodulator, decoder, display device;

Type of communication channel - telephone, mechanical;

Transfer rate and amount of information;

Ways of information transformation;

Channel capacity;

Signal volume and communication channel capacity;

Noise immunity;

Information and hardware redundancy of the channel;

Reliability of communication and transmission over the channel;

Level of signal attenuation in the channel;

Information coordination of channel links;

Mobility of the transmission channel.

A temporal sign of information can be introduced into the automated process control system, which assumes a single time system with a centralized reference scale. For information communications of automated process control systems, a characteristic feature is the action in real time.

The use of a unified time reference system ensures the fulfillment of the following tasks:

Documenting the time of receiving, transmitting information;

Logging of events occurring in the process control system;

Analysis of production situations on a time basis (order of receipt, duration);

Accounting for the time of information passing through communication channels and the time of information processing;

Management of the order of reception, transmission, processing of information;

Setting the sequence of control actions within a single time scale;

Display of the common time within the APCS coverage area.

When creating an automated process control system, the main attention is paid to the signals associated with the interaction of individual elements. Signals of human interaction with technical means and some technical means with other technical means are subject to study. In this regard, the following groups of signals and codes are considered:

The first group is stylized languages ​​that provide economical input of data into technical means and their output to the operator. By the nature of the information, technical and economic data are distinguished.

The second group - solves the problems of data transmission and docking of technical means. Here the main problem is the fidelity of the message transmission, for which error-correcting codes are used. Information compatibility of technical means is ensured by the installation of additional matching equipment, the use of auxiliary programs for data conversion.

The third group is machine languages. Usually, binary codes are used with data protection elements on a digital module, with the addition of a code with a check bit.

General technical requirements for automated process control systems for information support:

1) maximum simplification of information coding due to code designations and repetition codes;

2) ensuring ease of decoding output documents and forms;

3) information compatibility of automated process control systems with related systems in terms of content, coding, form of information presentation;

4) the possibility of making changes to previously transmitted information;

5) ensuring the reliability of the system's performance of its functions due to the noise immunity of information.

The APCS personnel interacts with the CTS, perceiving and entering technological and economic information. In addition, the operator interacts with other operators and higher-level personnel. To facilitate these links, measures are being taken to formalize information flows, to compress and streamline them. The computer transmits information to the operator in the form of light signals, images, printed documents, sound signals.

When the operator interacts with UVK, it is necessary to ensure:

Visual display of the functional-technological scheme of the control object, information about its state in the scope of functions assigned to the operator;

Displaying the connection and nature of the interaction of the control object with the external environment;

Alarm about violations in the operation of the facility;

Rapid identification and elimination of faults.

Separate groups of elements, the most essential for the control and management of an object, are usually distinguished by size, shape, color. The technical means used to automate control allow you to enter information only in a certain predetermined form. This leads to the need to encode information. Data exchange between the functional blocks of the control system must be carried out by complete semantic messages. Messages are transmitted by two separate data streams: informational and control.

Information flow signals are divided into groups:

measured parameter;

measuring range;

States of the functional blocks of the system;

Addresses (belonging of the measured parameter to a certain block);

time;

Service.

To protect against errors in the exchange of information through communication channels at the input and output of the equipment, redundant codes should be used with their checking for parity, cyclicity, iteration, and repeatability. Information security issues are related to ensuring the reliability of the control system, forms of information presentation. Information must be protected from distortion and misuse. Information protection methods depend on the operations performed, on the equipment used

Operational staff The process control system consists of technologists-operators of the automated control system who control the work and control the TOU using information and recommendations on rational management developed by the automation systems of the process control system, and the operational personnel of the process control system, which ensures the correct functioning of the complex of hardware and software APCS. Repair personnel are not included in the operational personnel of the process control system.

During the process of designing the process control system, mathematical and linguistic support is developed, which are not explicitly included in the functioning system. Mathematical support of the process control system is a set of methods, models and algorithms used in the system. Mathematical support of the process control system is implemented in the form of special software programs.

The linguistic support of the process control system is a set of language tools for communication of the operational personnel of the process control system with the means of the CT system. The description of the language means is included in the operational documentation of the organizational and software systems. Metrological support A process control system is a set of works, design solutions and hardware and software tools aimed at providing the specified accuracy characteristics of the system functions implemented on the basis of measuring information.

The operational personnel includes technologists-operators of the automated technological complex, who manage the technological facility, and the operational personnel of the automated process control system, which ensures the functioning of the system. Operational personnel can work in the control loop and outside it. In the first case, the management functions are implemented according to the recommendations issued by the CCC. In the second case, the operating personnel sets the operating mode for the system, controls the operation of the system, and, if necessary, assumes control of the technological object. Repair services are not included in the APCS.

Dispatching service in APCS is located at the junction of process control and production management. The operator and dispatcher stations of the automated control system provide an economical combination of the capabilities of operational personnel and the capabilities of technical means.

Introduction 2

1. Development block diagram 6

2. Development of electrical circuit diagram 8

3. Settlement part 11

4. Design development 16

Conclusion 19

List of sources used 20

Annex A - List of elements

Introduction

Temperature measurement and control is one of the most important human tasks, both in the production process and in everyday life, since many processes are temperature-controlled, for example:

Heating regulation based on measuring the temperature difference of the coolant at the inlet and outlet, as well as the temperature difference between the room and the outside;

Regulation of water temperature in the washing machine;

Temperature control of an electric iron, electric stove, oven, etc.;

Temperature control of PC nodes.

In addition, other parameters such as flow, level, etc. can be indirectly determined by measuring the temperature.

Electronic systems for automatic temperature control are widely used in warehouses finished products, foodstuffs, medicines, in chambers for growing mushrooms, in industrial premises, as well as in the premises of farms, poultry houses, greenhouses.

Automatic control systems are designed to control technological processes, while the nature of their behavior and parameters are known. In this case, the object of control is considered as deterministic.

These systems control the relationship between the current (measured) state of the object and the established “norm of behavior according to the known mathematical model of the object. Based on the results of processing the information received, a judgment is issued on the state of the control objects. Thus, the task of the SAC is to assign an object to one of the possible qualitative states, and not to obtain quantitative information about the object, which is typical for IS.

In SAK, thanks to the transition from measurement absolute values to relative (as a percentage of the “normal” value), the efficiency of work is significantly increased. With this method of quantitative assessment, the SAC operator receives information in units that directly characterize the level of danger in the behavior of the controlled object or process.

Automated control systems in flexibleproduction systems (GPS)

SAC GPS is its most important module, since it determines the possibility of implementing an unmanned production process.

SAC solves the following tasks:

• obtaining and presenting information about the properties, technical condition and spatial location of controlled objects and the state of technical about logical environment;
• comparison of the actual values ​​of the parameters with the given ones;
• transfer of information about discrepancies for decision-making at various levels of management of the State Fire Service;
• obtaining and presenting information on the performance of functions.

SAC provides: the possibility of automatic restructuring of control facilities within the specified range of controlled objects; compliance of the dynamic characteristics of the ACS with the dynamic properties of controlled objects; completeness and reliability of control, including control of transformation and transfer of information; reliability of controls.

According to the impact on the object, control can be active and passive. The most expedient and promising is the active control of product parameters and modes of technological processes and environments in the processing zone, since it allows you to provide regulation or control of them and eliminate (reduce) the appearance of defects.

Rice. 1.1 - Relationships between ACS and GPS elements

1 - material flows; 2 control signals; 3 control and measurement information.

The typical structure of the SAK (Fig. 1.2) flexible production systems includes three levels. The upper level provides general control over the aggregate of the flexible production module and coordinates them, reconfigures and repairs, issues information to the control panel of flexible production systems, receives, processes and summarizes information coming from the middle level; control of the volume and quality of products and tools; control over the execution of a set of operations performed by flexible production modules (FPM).

Rice. 1.2 - Structure of the ACS in the GPS

The middle level provides control of the GPM and presentation to the upper level of generalized information about the properties, technical condition and spatial location of controlled objects and components of the GPM. At the same time, the following tasks are solved: quality control of the manufactured product at the GPM, self-control and control of the functioning of the lower level; processing of information about the parameters of the technological environment.

The lower level provides control of processing and assembly objects, technical condition and spatial arrangement of HPM components (CNC machines, PR). At this level, the SAC solves the following tasks: input and output control of the production facility; obtaining and processing information about the controlled parameters of the processing or assembly object in the process of processing; transfer of information to the middle level; transition control. The means of control at the lower level are positioning sensors and control of the technological environment (temperature, pressure, speed, humidity), etc.

In this case, the measurement parameters can be spaced both in time and space. So some of the parameters can be controlled in the processing area, another - during transportation, the third - during storage, etc.

In principle, it is possible to share control between different processing cells and build it according to one of the following principles: with rechecking the control parameters on the next cell in full or in part; with the division of the complete group of tested - irl.meters between the output of the previous and the input of the next cells; with no re-control at the input of the next cell.

Control in the processing zone includes control of the correct installation and fixation of the workpiece in the clamping device of the machine, and in the case of active control, a number of geometric (dimensional and shape parameters) characteristics.

To ensure product quality, not only product parameters are controlled, but also a number of tool parameters (change, wear rate, blade temperature), machine tool (workpiece clamping and positioning, absence of foreign objects in the processing area, deformation of machine parts), processing mode (force, speed , cutting power, torque, feed and depth of cut), process environment (temperature and coolant flow, external influencing factors, including vibration, temperature, pressure and air humidity) and supporting systems.

The controlled parameters of the technical means of the GPS can be divided into functional parameters into the parameters of the intended purpose, power supply, operating modes, readiness for operation, control circuits, safety, as well as parameters that determine the performance and reliability of the GPS elements.

The upper-level computer makes a decision on the mode of operation of the ACS according to information from automatic cells and provides periodic self-control of its work.

In the reconfiguration mode, control information is sent to the upper-level computer, which decides on the reconfiguration of the control system at the middle and lower levels. The computer of the lower level establishes a set of controlled parameters and functions of processing objects and control standards.

Fallback mode is initiated by any level of ACS. At the lower level, it is caused by an increase in the acceptable level of rejects, a deviation from the norm of the GPM parameters or the controls themselves.

The nominal mode of operation of the ACS The alarm signal from each level is transmitted to a higher level is displayed on the control panel of the GPS.

The SAK software (SW) consists of:

• Software for monitoring the progress of the manufacturing process at specific workplaces of the State Fire Service;
• Control system software as a control subsystem:
• SAC software implements following features:
• Automatic collection of information about the actual release of parts on controlled equipment;
• Automatic accounting of equipment downtime and differentiation for reasons;
• A documented call to the repair services of the workshop;
• Issuance of operational information on the progress of production, downtime to the line personnel of the shop during the shift;
• Automatic reception and processing of information about the dimensions of parts for the control of TP;
• Automatic processing of receiving control information.

SAC are divided into several classes, which are designed to measure the geometric, physical and mechanical parameters of parts and assembly units and electrical parameters and characteristics.

1 Development of an electrical block diagram

The electrical structural diagram is presented in the graphic part of the course project BKKP.023619.100 E1.

According to the condition of the course design, the developed scheme must meet the following requirements:

Device name -automatic control systems

Regulated (controlled) parameter - temperature;

Sensor thermoelectric;

Type, control device family microcontroller NEC

Executive (control) device DC motor;

Alarm - light

Electronic key bipolar transistor;

Supply voltage 220 V, 50 Hz;

Power consumed by the executive device 20 W;

Additional requirements forcourse design condition:

Design - panel

Indication of set and actual temperatures digital (3 digits)

When the temperature drops below the set limit, an alarm is triggered and the fan motor is switched off.

Working temperature range: 100…300 about C

The devices included in the circuit perform the following functions:

Converter AC/DC accepts AC input voltage, outputs a stabilized DC voltage with a high degree of accuracy.

The voltage-to-current converter is designed to convert AC voltage into a unified DC output signal (4 ... 20mA);

Electronic key are used to switch the control circuit;

DC motor regulates the temperature value at the output of the circuit;

Fan controls temperature range;

Light alarm turns on when the temperature drops below the set limit;

Reference voltage source for powering the ADC in the microcontroller.

1. Circuit operation:

The circuit is powered by a 220 V mains source with an industrial frequency of 50 Hz. AC power is used to power the circuit elements. DC converter. With two output channels with voltage 12V, 24V.

24V required for power supplyvoltage current converter (PNT).

12V is needed to power the DC motor.

The microcontroller is powered by a voltage of 5 V, from the stabilizer microcircuit D.A. 2.

The operation of the system is activated by closing the switch SA1.

Signals are received at the MC inputs, one of them is from the operator's console, the second is from the sensor.

The master device (operator's console) is the buttons SB1 "More", SB2 "Less", SB3 "Task", which are connected to the inputs of the microcontroller NEC , respectively P45, P44, P43.

The operator sets the required temperature value through the control panel. The value is written through the arithmetic logic unit to register1. Thus, the limits of the count are set.

The second, analog signal, fromtransmitter with fixed temperature measuring rangeconverter voltage current (PNT), acting on the input ANI 0 of the microcontroller, is converted using the built-in ADC into a discrete (digital code), then enters the memory register 2, and is stored until the comparison signal arrives.

The values ​​of register1 and register2 are compared on a digital comparator, and if the actual value decreases above the set value, the EC closes, an alarm is triggered, and the fan motor is turned off. And in the case of normal operation: the set and actual values ​​are the same, the fan controls the temperature range.

Also, the signal from registers 1 and 2 is fed to the mode selection circuit, and then to the decoder, which is needed to display the temperature values ​​on a digital display.

2. Development of an electrical circuit diagram

The electrical circuit diagram is shown in the drawing BKKP.023619.100 E3.

The stand supply voltage is 220V 50Hz.

However, a lower level voltage is used directly to power the circuit elements. To provide such power, AC is used in the circuit. DC series converter TDK lambda LWD 15. With two output channels voltage 12V, 24V. I chose this converter based on the required parameters, low cost and versatility. The operation of the system is driven by closing the switch SA1.

To display the work of the stand there is an indicator HL 1.

The operator's console contains 3 buttons KM1-1:

When the button SВ1 is pressed, the operator increases the temperature value, and the indication displays the set value at the time of entry.

By pressing the SВ2 button, the operator reduces the set temperature value and the display shows the set value at the time of entry,

By pressing SB3 the operator confirms the set temperature.

A thermal converter with a unified output signal of the KTXA type measures the temperature.The primary thermal converter (PP) is equipped with a measuring transducer (MT), which is placed in the terminal head and provides continuous temperature conversion into a unified output current signal of 4-20 mA, which is fed to the input of the microcontroller.

The primary thermal converters are thermoelectric converters KTKHA, KTKKhK, KTNN, KTZhK modifications 01.XX;

To complete the primary thermal converters, a measuring transducer with a fixed temperature measurement range PNT was used.

I chose PNT type KTXA 01.06-U10 - I-T 310 - 20 - 800. class 0.5; (0 ... 500)°С, 4-20 mA- cable thermocouple with chromel-alumel graduation, constructive modification 01.06-U10, terminal head made of polymer material with measuring transducer PNT, working junction insulated(AND), heat-resistant cover(T 310) diameter 20 mm. installation length ( L) 800 mm. Transmitter type PNT, accuracy class 1 in the temperature range O - 500 ° C. Unified output 4-20 mA.

The brand's LED is used as a light signaling AL308.

Digital indication - ALS 324 A with a common cathode.

Chip stabilizer KR142en5a, necessary to power the microcontroller NEC.

I chose an electronic key on a bipolar transistor KT805 A. Since its parameters satisfy the condition.

The central and basic element is the microcontroller NEC 78K0S/KA1+ series. I chose this MK from forlow cost, the required number of pins and the right parameters. MK NEC has a standard structure. It contains a processor, internal read-only memory for program storage (in NEC IROM terminology), internal random access memory for data storage (IRAM), and a set of peripherals.

Some characteristicsmicrocontroller NEC 78K0S/KA1+ series.

Figure 2.1 microcontroller pin assignment NEC

Reference voltage source (ION) D.A.1 used to power the ADC in the microcontroller.ION connected to reference voltage input AVref.

ION MAX6125 I chose based on the necessary requirements. U in : 2.7 ... 12.6 V, U out : 2.450 ... 2.550 V.

Below are ION firms MAX , for clarity.

Figure 2.2 MAX

3. Settlement part

3.1.1. Electronic key calculation

Figure 3.1 Calculated scheme

Diode VD 1 performs the function of protecting the switching device: DC motor M. I chose the KD 105B diode from for suitable parameters and examples of other circuits.

3.1.2. We calculate the circuit parameters to select a transistor.

3.1.3. We calculate the rated load current according to the formula:

(3.1)

3.1.4. We calculate the collector current taking into account the starting mode according to the formula:

(3.2)

3.1.3. Initial data

Collector supply voltage U pit = 12 V.

Load current I n \u003d 3.3 A.

U o out DD 1< 0,6В

U 1 out DD 1 \u003d U power - 0.7 \u003d 4.3V (3.3)

We select a bipolar silicon transistor KT 838 A in terms of load current and supply voltage.

The bipolar silicon transistor KT 838A has the following parameters:

H21 e \u003d 150 - 3000

Uke us = 5V

Ube us = 1.5V

Uke max =150 V

Ik max \u003d 5 A

Pk max =250 W

U be then \u003d 1.5V

Calculation procedure

3.1.4 At the microcontroller output DD 1 discrete signal 0 or 1. When the signal is low, the transistor VT 1 must be securely closed, fully open and saturated when high. To do the first one:

U o out DD 1< U бэ порог. (3.4)

0.6V< 1,5В.

3.1.5. We calculate the base current at which its saturation mode is ensured by the formula:

(3.5)

3.1.6 Calculate the current flowing through the resistor R11

(3.6)

K base current safety factor, taking into account the aging of the transistor K = 1.3

3.1.7. We calculate the resistance of the resistor R11

(3.7)

Choosing the resistance of the resistor R11 from the standard range of nominal resistance values, equal to R \u003d 75 Ohm.

R11

Resistor S2-33N-0.25-75 Ohm 5% OZHO.468.552 TU

3.1.8. We calculate the power of the resistor R11

(3.8)

Choosing a resistor R 11 0.1 W

3.1.9. Finding the power dissipated by the transistor

(3.11)

Since P VT 1< P k max , а именно: 16.5W< 250 Вт, транзистор выбран правильно.

3.1.11. Because u bae us \u003d 1.5 V, then we take the switching voltage of the transistor from the closed state to the open

(3.12)

and the switching voltage from open to closed

(3.13)

The corresponding base currents will be I b + \u003d I b - \u003d 0.039A

(3.14)

1. calculation of light signaling:

U pet

Figure 1.3 - Calculated scheme

3.2.1. Initial data:

Supply voltage: U pit = 5 V

LED AL 308, with parameters:

Direct voltage drop on the LED: Upr \u003d 2 V

Rated forward current of the LED: Ipr.nom.=10 mA

Calculation procedure

3.2.2. We calculate the resistance of the resistor R 9 , according to the formula:

R9 = (3.13)

R9=

3.2.3 Choosing a resistance R9 from a number of standard, equal to 300 Ohm

According to the results of calculations, we choose as a resistor R9

C 2-33-0.125-300 Ohm ± 5% OZHO.467.173.TU

3.3. We calculate the parameters of the resistor R7 , which is located at the input of the MK ANI 0 and we exit with PNT:

3.3.1. Knowing the unified current signal, which is equal to 5 ... 20mA and the supply voltage equal to 5V, we find the resistance using the formula of Ohm's law:

4 Design development

4.1 PCB dimensioning

Printed circuit board a plate of electrically insulating material, rectangular in shape, used as a base for the installation and mechanical fastening of mounted radio elements, as well as for their electrical connection to each other by means of printed wiring.

For the manufacture of printed circuit boards, foil fiberglass is most often used. The dimensions of each side must be a multiple of: 2.5, 5, 10 with a length of up to 100, 350 and more than 350 mm, respectively. The maximum size of any side cannot exceed 470mm, and the aspect ratio must be no more than 3:1.

Determining the size of the board is reduced to finding the total installation areas of small-sized, medium-sized and large-sized elements. And for this you need to know the overall dimensions of each element. Small-sized include all miniature elements, namely, resistors (P ≤ 0.5 W), small-sized capacitors, diodes, etc. For medium-sized microcircuits in rectangular cases, resistors (P ≥ 0.5 W), electrolytic capacitors, etc. To large-sized variable resistors and capacitors, semiconductor devices on radiators, etc.

Overall dimensions, as well as the installation area of ​​all elements located on the board, are shown in Table 4.1.

Table 4.1 Overall dimensions of elements and their installation area

Element designation	Item type	Overall dimensions, mm 2	Quantity, pcs	Installation area, mm 2	Dimensions
	2
R1-R6,R8,R10 , R12,R13	C1-4	6 x 2.3			mg
R7, R9, R11	C2-33	7 x 3			mg
	KT502V	5.2 x 5.2		27,04	mg
VT 2- VT 4	KT3142A	5x5			mg
VD 1	KD 105B	7 x 4.5		31,5	mg
	MAX6125	3 x 2.6		7, 8	Wed
	kr142en5a	16.5 x 10.7		176,6	Wed
	78K0S/KA1+	6.6 x 8.1		53,9	Wed
	HC-49 U	11x5			mg
C1, C5	K50 - 6	4 x 7			sg

Continuation of table 4.

С2, С3, С4	K73-17	8 x 12			sg
C6, C7	KM-5B	4.5x6			mg
HG1-HG3	ALS 324 A	19.5 x10.2		596,7	sg

Find the area occupied by elements of the same type of dimensions

S mg = 138+63+27.04+75+31.5+55+54=393.54 mm 2 (6)

S sg = 176.6+7.8 +53.9+56+288+596.7=1179 mm 2

According to the data given in Table 4.1, we calculate the area of ​​the installation zone

S mz \u003d 4 ∙ S mg + 3 ∙ S sg +1.5 ∙ S kg, (4.1)

where S mz the area of ​​the calculated installation zone;

S mg total area occupied by small radioelements, cm 2 ;

S sg total area occupied by medium-sized radio elements, cm 2 ;

S kg total area occupied by large radioelements, cm 2 .

S ms = 4∙ (393,54) + 3∙ (1179) \u003d 5111.16 mm 2 \u003d 51.1 cm 2

The area of ​​the printed circuit board must not be less than 52 cm 2 .

5. Development of the stand design

The view block drawing is presented in the graphic part of the course project BKKP.023619.100 VO

When developing a design, the following basic requirements must be taken into account:

The design of the device must comply with the operating conditions

The device and its parts should not be overloaded during operation from the impact on them of current, vibration, temperature and other loads. The elements of the devices must withstand their permissible values ​​for a certain time, provided that they operate without failure.

Most of the parts are mounted on a printed circuit board made of one-sided foil fiberglass. It is strengthened inside the case, where the power source is also placed. The device controls are located on the front panel. Toggle switch "network", fuses, light signaling, digital indication, buttons.

The automatic control system is placed in the case Bopla model NGS 9806 c made changes and overall dimensions 170x93x90 made of plastic.

There are mounting holes on the body for panel mounting.

On the front panel there are: LED, digital indication, light signaling, and button modules.

Toggle switch L2T-1-1 has only two positions: on toggle switch up, off toggle switch down. A terminal block is attached to the rear wall of the case for connecting the converter, PNT, fan motor to electrical network 220 V 50 Hz.The power connection is made through a standard cord with a plug.

The printed circuit assembly is attached to the case using four M3-1.5 GOST17473-72 screws, which cut through the board into the case protrusions. These protrusions are made by casting together with the body.

AC-DC firm converter TDK lambda LWD series 15 is attached to the bottom wall of the housing with 4 screws M3-1.5 GOST17473-72.

Conclusion

In this course project, an automatic temperature control system was developed, during the development, the parameters of the specified devices were calculated, in particular an electronic key, a resistor for a light alarm and a resistor at the PNT output. In addition, the dimensions of the printed circuit assembly were calculated. All elements of the system are widely used, readily available for purchase and interchangeable, which ensures high maintainability of the circuit.

The graphic part of the course project is represented by an electrical structural diagram and an electrical circuit diagram of the stand and a general view drawing.

A text editor was used in the design of the course project. Microsoft Word 2007 and graphics editor Splan 7.0

List of sources used

1 Industrial electronics and microelectronics: Galkin V.I., Pelevin

E.V. Proc. Minsk: Belarus. 2000 350 pp.: ill.

2 printed circuit boards. Technical requirements TT600.059.008

3 Rules for the implementation of electrical circuits GOST 2.702-75

4 Fundamentals of automation / E.M. Gordin M .: Mashinostroenie, 1978 304p.

5 Semiconductor Devices: A Handbook / V.I. Galkin, A.A. Bulychev,

P.N.Lyamin. Mn.: Belarus, 1994 347

6 Diodes: Handbook O.P. Grigoriev, V.Ya. Zamyatin, B.V. Kondratiev,

S.L. Pozhidaev. Radio and communications, 1990.

7 Resistors, capacitors, transformers, chokes, switching

REA devices: Ref. N.M. Akimov, E.P. Vashchukov, V.A. Prokhorenko,

Yu.P. Khodorenok. - Minsk: Belarus, 1994.

8 Semiconductor devices: Reference book V.I. Galkin, A.L. Bulychev,

P.M. Lyamin. - Minsk: Belarus, 1994.

9 Usatenko S.T., Kachenok T.K., Terekhova M.V. Execution of electrical circuits according to ESKD: a Handbook. Moscow: Standards Publishing House, 1989.

10 OST45.010.030-92 Molding of leads and installation of electronic products on printed circuit boards.

11 STP 1.001-2001 Registration rules explanatory note 1 course and diploma project.

12 Information from the sitehttp://baza-referat.ru/Systems_of_automated_control

13 Information from the sitehttp://forum.eldigi.ru/index.php?showtopic=2

Send your good work in the knowledge base is simple. Use the form below

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Introduction

2.3 Structure of APCS DNS

2.4 Complex of technical means 20

2.4.6 Flowmeter Metran-350

2.4.8 Vibration transducer DVA-1-2-1 27

2.4.10 3050 OLV Moisture Analyzer

2.4.12 Cable products

3.1 Rationale for choosing a controller

3.2 Basic technical data of the SLC controller 5/04

3.3 Controller configuration

3.4 Programming the controller

3.6 Operator interface

4. Calculation of the reliability of the designed system

4.1 General

4.2 Failure rate

4.3 MTBF

4.4 Probability of failure-free operation

4.5 Average recovery time

4.6 Conclusion by section

5. Evaluation of economic efficiency

5.1 Methodology for calculating the economic indicators of the designed system

5.2 Calculation of non-recurring costs

5.3 Calculation of generalizing indicators of economic efficiency

5.4 Section Conclusions

6. Safety and environmental friendliness of the project

6.1 Ensuring the safety of workers

6.1.1 Characteristics of working conditions

6.1.2 Personal protective equipment

6.1.3 Electrical safety

6.2 Environmental assessment of the project 80

6.2.1 Impact of BPS facilities on the environment

6.2.2 Impact of BPS on surface and groundwater

6.2.3 Land cover

6.2.4 Fire fighting measures

6.3 Forecasting emergency situations

6.4 Section Conclusions

Conclusion

List of sources used

AT conducting

Modern oil and gas production enterprises are complex complexes of technological facilities dispersed over large areas, the size of which reaches tens and hundreds of square kilometers.

The successful process of processing and pumping oil and gas depends on the strict control and maintenance of pressure, temperature, flow rate, as well as on the quality control of the output product. Maintaining the parameters of high-speed processes with a given accuracy at a given level with manual control is not possible. Therefore, modern petrochemical and oil refining production is possible only if technical installations are equipped with appropriate automatic measuring instruments, information-measuring systems and automatic control systems. In this way, modern stage development of oil and gas production and processing is unthinkable without the use of instrumentation and microprocessor technology.

APCS provides: presentation of operational information to personnel for diagnosing and predicting the state of equipment, monitoring and control of technological processes and equipment, providing an opportunity to find out the reasons for a violation of the normal operating mode, analysis of various working situations.

In this graduation project, the development of a booster automation project is carried out. pumping station DNS-7 of the Fedorovskoye oil and gas field, designed to control, manage, regulate and signal accidents occurring at this facility. Due to the fact that DNS-7 was built and put into operation in the late 70s, devices and automation equipment at this moment morally obsolete and did not provide a sufficient level of information content and controllability of the system. In order to simplify the operation process and increase the reliability of the system in this project, old instruments and sensors were replaced with new, more modern ones and a microprocessor controller was used for centralized control of the technological process.

1. general characteristics automation object

1.1 Information about the control object

Booster pumping station DNS-7 is part of the Fedorovskoye oil and gas field.

This field was discovered in 1971. The deposits are at a depth of 1.8-2.3 km. The initial flow rate of wells is 17-310 tons/day. Oil density is 0.86-0.90 g/cm3.

The Fedorovskoye oil and gas field is part of OAO Surgutneftegaz, one of the largest Russian fields. The scope of the company's activities covers exploration, development and development of oil and oil and gas fields, production and sale of oil and gas, production and marketing of petroleum products and petrochemicals.

Surgutneftegaz is distinguished by stable growth dynamics based on high pace production growth and constant increase in raw material potential. The flexible long-term development strategy of the company is based on many years of experience and the use of the latest technologies.

The territory along the middle course of the Ob River, near the city of Surgut, in the mid-sixties became one of the first oil and gas production areas in Western Siberia. In 1993 on the basis of the property complex production association“Surgutneftegaz” was founded joint-stock company of the same name.

Currently, more than 50 divisions of OJSC “Surgutneftegas” perform a full range of works on exploration, development and development of oil and oil and gas fields, production and sale of oil and gas.

1.2 Description of the technological process

A single-pipe pressure system was adopted as a field collection scheme for oil, petroleum gas and water, which ensures the transportation of produced oil through all technological facilities, including oil treatment facilities, due to wellhead pressures in any way of their operation. Pressure two-pipe and multi-pipe collection systems are allowed only in the section from group installations to oil treatment installations with separate collection of watered and non-watered or mixed oil, respectively. The desire to maximize the use of the energy of the reservoir leads to the fact that the flowing well is transferred to the mechanized production method only when the flowing completely stops. This leads to the need to build booster pumping stations (BPS) combined with separation tanks. In addition, field gas gathering networks are being built to collect gas from the separated gas at the BPS.

In the case of a high water content (over 30%) of the transported liquid, separation plants are used. The water-oil mixture first enters the inlet separators SV-1/1 and SV-1/2, which are designed to separate the bulk of the liquid from the gas; at the same time, these devices are gas-liquid flow pulsation dampers. Further, the liquid is drained into the separators of the first stage С-1/1…С-/4 under the action of the hydrostatic liquid column (due to the difference in the installation heights of the devices). After the first stage separators, the watered, degassed oil enters the settling tanks O-1 and O-2, where the oil is separated from the water. Partially degassed oil enters the Heater-Triter X/T-1 and X/T-2 preliminary water discharge unit. Then oil with an average water cut of less than 10% enters the second stage separator C-2/1 and C2/2, where the final degassing takes place. after that, oil is accounted for by volume, weight (28-280 m 3 /h) and supplied to the oil pipeline. The gas released from the oil in the separation units and in the Heater-Triter preliminary dehydration unit (furnace) is fed to the GPP, as well as to the flare. Formation water separated at dewatering plants enters reservoirs, and then to cluster pumping stations, from where it is pumped into injection wells.

The master plan of the DNS is presented in Appendix A.

• 1.3 Modern approach to the development of automated control systems for DNS
• As part of the reconstruction of the booster pumping station BPS-4A, OJSC "Surgutneftegas" successfully put into commercial operation a new process control system developed using the TRACE MODE SCADA system (Russia). APCS DNS-4A controls over 1600 parameters of the oil treatment process and provides their visualization on 18 graphic mnemonic diagrams and on archived trends. Automatic and remote manual control of gate valves and valves is implemented in the automatic process control system DNS-4A. The system is integrated with oil and gas metering units. Data from SCADA TRACE MODE is constantly transmitted to the corporate information system JSC "Surgutneftegaz" The APCS DNS-4A uses Austrian controllers Bernecker & Rainer (B&R), the driver for which is included in the extensive library of free TRACE MODE drivers (more than 1585 free drivers). This is already the second BPS owned by Surgutneftegaz, whose automation system is based on SCADA TRACE MODE. Earlier, in 2003, an automated process control system for the DNS of the Piltanskoye field was introduced. The development of the first automated process control system for DNS was carried out by the company LLC "AT" - an Authorized SCADA TRACE MODE system integrator from Moscow. The second APCS of the booster pumping station was completely designed and implemented by the employees of OJSC "Surgutneftegaz" on their own.
• Before starting work on the project, two specialists of OJSC "Surgutneftegas" were trained at the authorized training center of AdAstra Research Group and received the qualification of TRACE MODE certified engineers. When developing the automatic process control system DNS-4A, they took into account all the comments and wishes of technologists, so that the new system became more ergonomic and easy to use. The specialists of OJSC "Surgutneftegas" appreciated the flexibility of TRACE MODE as a universal SCADA system for oil production facilities. Currently, projects for the use of SCADA TRACE MODE at several more BPS and other facilities of OJSC "Surgutneftegas" are being considered. The list of TRACE MODE SCADA system implementations in the oil industry continues to grow.
• The qualified development of control algorithms for the automatic process control system for oil preparation and pumping allowed IBS specialists to ensure the minimum necessary involvement of the personnel of technological facilities in the process of controlling mechanisms and assemblies. This approach significantly reduces the load on the operator and thereby reduces the possible Negative influence "human factor"on the growth of production costs, the creation of prerequisites for emergency situations and pollution environment.
• About 95% of Russian oil is produced today by waterflooding. As a result, the water cut of oil during the production process increases to 80 percent or more, which leads to the need for additional measures for oil treatment and causes a constant increase in the cost of production. More precisely, with an increase in the water cut of the oil and gas emulsion, the costs of separating oil, water, associated gas, and mechanical impurities increase, and at the booster pumping station (BPS) there are more and more functions characteristic of an oil treatment and pumping unit (UPPN). This means that the traditional DNS in terms of functionality is gradually evolving towards the UPPN. At some point, oilmen realized the inefficiency of distillation through infield pipelines (the length of which can often be quite significant) of an emulsion containing 80-90% water. In this regard, tools and units began to be used to reduce water cut directly at the BPS. Although sometimes multi-phase pumps are installed, their use is rather limited. Basically, in the management of water cut, it is transferred to the optimal management of the oil preparation process at the BPS.
• Obviously, it is necessary to solve the following problem - to keep the costs of oil treatment at the same level and at the same time maintain the level of oil quality.
• There are objective factors that impose certain requirements on the automated process control system for oil treatment in Western Siberia - the remoteness of the treatment sites from settlements, the harsh climate and the organization of work resulting from this (shift personnel, turnover of qualified personnel), fire hazard, and underdevelopment of infrastructure. These circumstances should give rise to a new approach to the construction of process control systems, in which increased attention should be paid to reliability and labor intensity.
• It was decided to deploy a project for the introduction of a new type of automated process control system at the Permyakovskoye and Koshilskoye fields of the Nizhnevartovsk Oil and Gas Production Enterprise (NNP), a TNK company. NNP is one of the city-forming enterprises of this region. It develops a number of deposits located at a considerable distance from the city (up to 450 km), which determines the presence of certain features in its activities. So, in addition to the harsh climatic conditions that are typical for this region as a whole, all work at the NNP facilities is carried out on a rotational basis, which implies increased costs for the life support of workers (up to imported drinking water) to maintain the infrastructure. That is why any opportunities for optimizing economic indicators, reducing labor costs and the negative impact of the role of the "human factor", and, consequently, the cost of oil production are very relevant here. In addition, for two BPSs, the company has already purchased imported Sivalls preliminary water discharge installations, which in themselves required a new level of industrial automation.
• The general task assigned to IBS specialists was formulated in purely economic terms - to improve the quality of oil treatment, while reducing the cost of this process. Particular attention was paid to the possibility of subsequent stabilization of the cost level, compensating for the expected increase in the water cut of the extracted oil. The project to create a new generation of automated process control systems for the BPS, which are part of the production structure of oil producing enterprises of TNK, was implemented by IBS in the period 2001-2002. During the implementation of the project, the entire cycle of work required for the commissioning of the automatic process control system for DNS was completed - from the development of technical solutions for automation to commissioning at the facility and staff training. Logically, 3 main levels of the system were identified: the oil treatment site, the oil field level (distance from the oil treatment sites is 50 km), the OGPD level (in a city 400 km away from the oil field). Thus, it turned out 3 zones covered by the project.
• The first stage of the work provided the traditional functions of monitoring the technological process directly at the oil treatment site. Technological goal This stage of the project was to ensure a stable water cut of the output oil with unstable characteristics of the water-and-gas emulsion entering the site. The installation of control and measuring equipment (more than 200 types) was performed, the InTouch SCADA package for 1500 tags was installed and configured (at each preparation site), as well as the Avantis.Pro routine maintenance support system.
• The development implemented at the second stage (also based on the Wonderware product line - Industrial SQL, Active Factory, Suite Voyager, SCADA Alarm) allows you to separate the event stream coming from the technological control object and distribute its various components between the workstations of specialists (operator , technologist, mechanic, power engineer, geologist) capable of making decisions on these events.
• Finally, in the third phase of work, the paradigm of "process" management was implemented.
• If we talk about the technical prospects of the project, the following should be noted. Building a vertical "platform and InTouch - Industrial SQL technological server - workplaces in NGDU based on MS Office + Active Factory" allows you to increase both the number of connected technological objects and the number of jobs in NGDU. A potential bottleneck is the tagged capacity of Industrial SQL, since through it all technological parameters are delivered to the oil and gas production department. The installed capacity (100,000 tags), according to our calculations, allows us to connect all the pads of the field, and thus come to a situation where all the technological information from the field is concentrated in one place and in a single format, which is extremely attractive from the point of view of the possibility of in-depth analysis of the flow TP.
• Let us indicate the main items of operating costs, which were positively affected by the creation of this APCS:
• repairs of technological equipment, elimination of accidents and associated consumption of components, energy carriers, materials, transport resources;
• consumption of operating materials;
• fines (for example, for violation of the ecological state of the adjacent territory);
• expenses for ensuring quality and quantity control of delivered oil;
• payments to employees who were injured in accidents.
• These costs can be taken as economic criteria for assessing the effectiveness of automated process control systems. For various cost items, savings amounted to 5-30%, which was considered a result adequate to the investments made. Obviously, these indicators also indicate the success of the project as a whole.
• 2. Process automation
• 2.1 Target automation function
• Automation of production is carried out to facilitate the process of managing the facility, as a result of which there is no need to involve a large number of operators. The control post of the station is the control panel located in the control room. It provides remote monitoring and control of equipment, as well as operating modes of the main and auxiliary facilities. The automation scheme is presented in Appendix B.

The technological process must proceed as safely as possible in all its stages, for this, new, more accurate, compared to earlier developments, devices, sensors and actuators are used in the automation system. The system's capabilities in terms of monitoring process parameters, actuation of control circuits of instrumentation and emergency shutdown function independently of each other, this is implemented in order to ensure maximum safety of production. The design of the automated control system is carried out in such a way as to ensure safe, reliable and accurate control of the plant systems, as well as to provide for the operation of the plant in the most efficient mode.

2.2 Functions of the developed system

The urgency of creating a system has increased significantly in recent times in connection with the increase in the cost of oil, energy resources, reagents, the cost of maintaining maintenance personnel and maintaining the ecology of the environment.

The main functions of the process control system include:

collection of information about the controlled technological process of oil treatment;

transfer of control commands to the technical complex of the technical level;

registration of events (prehistory of events) associated with the controlled technological process;

registration of personnel actions;

notification of personnel about detected emergency events related to the progress of the controlled technological process;

direct automatic control of the technological process in accordance with the specified algorithms with the possibility of switching to manual mode, both from the automation panel and locally;

real-time display of technological parameters of the process at the automated workplace, as well as presentation of archival information in a form that is easy to understand;

archival database maintenance.

The means of achieving these goals is the use of modern technical means, including microprocessor ones.

The applied technical means should allow implementing single-loop, multi-loop and multi-connected systems of automatic control, signaling and protection from a given set of algorithms, as well as quickly convert and improve existing protection, control and signaling schemes.

The use of modern microprocessor tools should allow, if necessary, the development of a control system, as well as its connection with other information networks, including a higher level.

2.3 Structure of APCS DNS

In the APCS of the DNS, the main 2 levels of the hierarchy are distinguished:

lower level - the level of sensors, instruments, actuators;

the upper level - microprocessor controllers and automated workplaces of operators.

All lower-level sensors, devices and actuators are explosion-proof and are recommended for use in oil and gas industry. The main function of the lower level is the conversion of the necessary technological parameters into electrical signals and signal processing by the microprocessor controller.

The main functions of the upper level is to obtain information from the lower level, the transmission of control commands.

On the automation board based on the process controller of the automated process control system and secondary sensor devices, the following are implemented:

installation technological protection schemes;

schemes for collecting telemechanical information from primary sensors installed at technological facilities;

starting equipment;

manual control.

The equipment for interfacing with the process equipment is based on the SLC5/04 process controller manufactured by Allen Bradley with modules for inputting signals from measuring instruments and sensors installed on the process equipment, and control modules for starting equipment.

automated workplace operator is developed based on the Microsoft WINDOWS operating system using RSView32 SCADA system development tools.

The automated process control system provides for the possibility of regulated operator intervention in the course of the technological process (opening / closing electric shutters, redefining settings for regulators, etc.) by issuing commands from the operator's automated workplace, organized on the basis of an industrial personal computer.

2.4 Complex of technical means

All sensors, devices and actuators are made in an explosive design and are recommended for use in the oil and gas industry. The selected sensors have a high measurement accuracy and are resistant to various external influences.

2.4.1 Pressure gauge indicating signaling DM-2005 SG 1Ex

Pressure gauges showing signaling devices DM - 2005 Cg 1Ex are designed to measure the excess and vacuum pressure of various media and control external electrical circuits from a direct-acting signaling device.

The devices are explosion-proof with the type of protection "explosion-proof enclosure" and are marked for explosion protection 1ExdII VT4.

In terms of protection from environmental influences, the devices have the following versions:

in terms of weather resistance - ordinary and protected from dust and water ingress;

in terms of resistance to aggressive media - ordinary and protected from aggressive media.

Controlled media: non-aggressive, non-crystallizing liquids, gases, vapors, including oxygen.

Technical details:

instrument reading range, MPa

from 0 to 0.1; 0.6; 0.25; 0.4; 0.6; 0.1; 1.6; 2.5; 4.0; 6.0; 10.0; 16.0; 25.0; 40.0; 60.0;100.0;160.0;

instrument accuracy class 1.5;

overpressure measurement range should be from 0 to 75% of the reading range; vacuum pressure is equal to the range of indications;

instrument settings range: from 5 to 95% of the reading range - for the measurement range from 0 to 100%, from 5 to 75% of the reading range - for the measurement range from 0 to 75%;

minimum setting range, set by the signaling device from 0 to 10% of the setting range;

parameters of the signaling device: voltage of external switched circuits: 24; 27; 36; 40; 140; 220; 380V - for AC circuits and 24; 27; 36; 40; 110; 220 V - for DC circuits;

breaking power of contacts 10W DC and 20VA contacts; 30W direct and 50VA alternating current - for a signaling device with a magnetic preload of contacts;

current up to 1 A;

voltage deviation from nominal values ​​should be from + 10 to - 15%;

AC frequency (50+/-1) Hz;

limit of permissible basic error of operation of the signaling device: +/- 2.5% of the range of indications - for devices with sliding contacts; +/- 4% of the range - for devices with magnetic contacts;

devices are resistant to ambient temperature from -50 to + 60 C and relative humidity up to 98% at 35 C and lower temperatures of moisture condensation;

devices are resistant to vibration with a frequency of (5 - 35) Hz with a displacement amplitude of 0.35 mm.

2.4.2 Ultrasonic level detector SUR-3

Ultrasonic level switch SUR-3 is designed to signal the position of the level of various liquid products at two points in process tanks and to control process units.

Technical details:

four optoelectronic keys of the "dry contact" type;

indication of the position of the first and second limit levels using LEDs;

maximum length of the sensitive element 4m (rigid SE) and 16m (flexible SE);

service life of at least 10 years;

Measured media: liquid (oil, dark and light oil products, liquefied gas).

2.4.3 Ultrasonic level detector SUR-5

The SUR-5 ultrasonic level switch is designed to issue an electrical signal to the automatic monitoring and control system when an emergency level of liquid products is reached.

Technical details:

two optoelectronic keys of the "dry contact" type;

indication of the position of the level with the help of LEDs;

operating overpressure 84…106.7 kPa;

operating temperature from -45 to +65 C;

sensing element length 0.25…0.4m;

mean time between failures is not less than 50000 hours;

service life of at least 10 years.

2.2.4 Ultrasonic level sensor DUU4

Ultrasonic level sensor DUU4 is designed to measure the level of various liquid products. Sensors can carry out:

contact automatic measurement of the level of liquids;

contact automatic measurement of up to four levels of separation of immiscible liquid products;

measuring the temperature of the controlled medium at one point;

measuring the pressure of the controlled medium.

Technical details:

output signal 4-20mA or dry contacts or RS-485(Modbus RTU);

operating overpressure 2 MPa;

operating temperature from -45 to +95 C;

sensing element length 4m (rigid SE) or 25m (flexible SE);

mean time between failures is not less than 50000 hours;

service life of at least 8 years.

2.4.5 Thermal converter with unified output signal METRAN 200T-Ex

The sensors are designed to continuously convert the temperature of liquids, steam and gases into a unified current electrical output signal of remote transmission, which can be used in systems for automatic control, regulation and registration of temperature at objects in various industries industry, energy, utilities.

Technical details:

range of measured temperatures 0 - 150 о С;

limit of permissible basic error? 0.5%;

additional sensor error caused by vibration, expressed as a percentage of the output signal range, should not exceed 0.25%;

the change in the value of the output signal caused by a change in the load resistance from 0.1 to 1.0 does not exceed? 0.1%;

additional sensor error caused by ambient temperature change in the operating range, expressed as a percentage of the output signal change range for every 10 ° C, does not exceed 0.45%;

length of the immersed part in the measurement zone 120 mm;

ambient temperature from minus 50 to 60 o C;

limit value of the output signal 4-20 mA;

load resistance connected at the output of the sensor, including the communication line - from 0.1 to 1.0 kOhm;

DC supply voltage 36 ? 0.72V;

power consumption, no more than 0.8 W;

dust and splash resistance IP 54;

climatic version and category U.2;

the assigned service life before decommissioning of the sensor is 12 years;

the mean time between failures is 32,000 hours;

sensor weight, no more than 0.73 kg.

2.4.6 Flowmeter Metran-350

The Metran-350 flow meter (jointly produced with Emerson Process Management) is designed to operate in systems for automatic control, regulation and control of technological processes in various industries, as well as in commercial accounting systems for liquids, steam and gases.

Main advantages:

simple installation in the pipeline through one hole;

installation in the pipeline without stopping the process (special design);

minimum probability of leakage of the measured medium;

lower pressure losses and shorter straight sections compared to flow meters based on orifice devices;

significant reduction in installation and maintenance costs due to the integral design;

ease of interfacing with existing control systems or flow computers via intelligent HART and Modbus communications protocol;

ease of reconfiguration of the dynamic range;

high reliability, no moving parts.

Measured media: gas, steam, liquid.

Measured medium parameters:

temperature: -40…400 °С - integral mounting and -40…677 °С - remote mounting;

excess pressure in the pipeline 25 MPa.

Limits of the basic permissible relative error of mass (volume) flow measurements up to ±1%.

Self-diagnosis.

Average service life - 10 years.

Calibration interval - 2 years.

Metran-350 flow meter operation principle is based on measuring the flow rate and quantity of a medium (liquid, steam, gas) by the variable pressure drop method using Annubar Diamond II+ (4th generation) and Annubar 485 (5th generation) averaging pressure tubes, on which a pressure drop occurs proportional to the flow. The sensors are installed perpendicular to the flow direction, crossing it along the entire section.

2.4.7 Intelligent pressure sensor Metran 100

Metran-100-DI intelligent pressure sensors are used to obtain analog data on overpressure at various units. Metran-100-DD sensors are used to measure the pressure difference at the inlet and outlet of the filters.

Ranges of measured pressures:

minimum 0-25 kPa;

maximum 0-25 MPa.

Basic error up to ±0.1% of range.

Versions:

ordinary;

explosion-proof (Ex);

Check interval: 3 years.

Warranty period: 3 years.

Sensor Capabilities:

control of the current value of the measured pressure;

control and adjustment of sensor parameters;

setting "zero";

system selection and unit setting;

setting the averaging time of the output signal (damping);

reconfiguration of measurement ranges, including non-standard ones (25:1, 16:1, 10:1);

adjustment to the "shifted" measuring range;

selection of the dependence of the output signal on the input value: (linearly increasing, linearly decreasing, proportional to the square root of the pressure drop);

sensor calibration;

continuous self-diagnosis;

testing and control of sensor parameters at a distance;

protection of settings from unauthorized access.

2.4.8 Vibration transducer DVA-1-2-1

DVA-1-2-1 is designed to measure the root mean square value (RMS) of vibration velocity. Output interface type: 4-20mA;

The vibration transducers are explosion-proof with the type of protection "intrinsically safe circuit" and marking for explosion protection 1ExibIICT5 according to GOST 51330.10.

Service life - 8 years.

2.4.9 Detector of pre-explosive concentrations of gases STM-10

Stationary signaling devices STM-10 are designed for automatic continuous monitoring of pre-explosive concentrations of multicomponent air mixtures of combustible gases and vapors.

Measuring range: 0-50% LEL.

Range of signal concentrations: 5-50% LEL.

Standard threshold setting: 1st - 7% LEL, 2nd - 12% LEL.

Alarm response time: no more than 10 s.

Warm-up time: no more than 5 minutes.

Ambient temperature: -60…+50 °С.

Power supply: 220 V (50 ± 1 Hz).

Service life: at least 10 years.

The signaling devices have a light signaling on the front panel for each channel when the threshold concentrations of combustible gases are reached or the sensor malfunctions.

2.4.10 3050 OLV Moisture Analyzer

The 3050 OLV analyzer determines the moisture content in a gas stream by measuring the vibration frequency of a quartz crystal.

When the crystal is blown with wet gas to be analyzed, water is adsorbed by a special coating on the crystal, causing a decrease in its frequency. The crystal is then blown over with a reference gas, which is the dried sample gas. In this case, the adsorbed water is removed from the surface of the crystal, and the frequency of its oscillations increases again.

The difference between these two frequencies is proportional to the water content of the gas.

The frequency of switching between the flow of the analyzed and reference gases, depending on the application, is programmed by the user.

Range: 0.1...2500 ppmv (calibrated), up to 9999 ppmv.

Units of measure: ppmv, ?C dew point, mg/m3;

Accuracy: +10% of reading in the range 0.1...2500 ppmv;

Sensitivity: +0.1 ppmv or 1% of reading;

Response time: no more than 1 min for 90% with a change in humidity from 1000 to 10 ppmv;

Analog output: 4...20 mA.

Relay outputs: 3 relays, for signaling a system error and exceeding the set concentrations;

Interfaces: RS-232, RS-485;

Environment parameters: Analyzer: 5...50 °С (-20...+50 °С in cabinet) .

2.4.11 IRFMD IR point hydrocarbon gas detector

Designed to measure the concentration of hydrocarbon gases in the air.

Specifications and Benefit:

analog signal 4-20mA;

indication of the level of gas contamination on a 4-digit display;

there is no need to perform current calibration;

RS-485 data link via Modbus RTU$ protocol

optical system with heating to remove condensation;

indication of contamination of the optical system;

protection from typical toxic substances;

works in an environment with insufficient oxygen content;

degree of protection IP66;

operating temperature from -45 to +75 C.

2.4.12 Cable products

The laying of cables at the facility is carried out along cable racks, and is carried out in accordance with the PUE ("Rules for the installation of electrical installations"). Overpasses are special structures for laying cables, protecting them from mechanical damage and bad weather. Control cables must be insulated with fireproof partitions. In accordance with the PUE, the minimum distance between intrinsically safe, low-current and power cables must be at least 50 cm.

This project uses several types of cables: KVVG - for laying from actuators to the control room, KVVGe - for laying from primary sensors to the control room, HV-1.0 - for internal disconnection of the cabinet unit, FTP - for connecting the controller with a computer, the minimum distance when joint laying with electrical circuits should be at least 50 cm.

3. Analysis and selection of software development tools

3.1 Rationale for choosing a controller

Industrial controllers are the brain of modern industrial automation systems. They are closest to the technological process. Their failure almost immediately leads to the failure of the entire industrial automation system. Almost all specialists who work in the field of industrial control systems have to deal with industrial controllers.

Dynamic growth Russian economy creates prerequisites for increasing demand for modern process control systems. According to research results, the annual growth of the funds market industrial automation in Russia is at least 25%. For comparison: the Western market of industrial controllers has an annual growth rate of no more than 4.6%. Exists great amount enterprises active in the field of industrial controllers. Some of the largest suppliers of control and process control in the world market are as follows: the Canadian company Control Microsystems, the Tekon group of companies is the leading Russian supplier APCS tools and systems, EleSy, Industrial Computer Systems, Emerson Process Management, Rockwell Automation, Metso Aytomation, Yokogawa Electric, Opto 22, Octagon, Siemens, Modicon, Remicont-130 and others. Products from these manufacturers are becoming less expensive, more thoroughly tested, and more widely available. Below is short review controllers from some manufacturers.

The Industrial Computer Systems company has released the third generation of monoblock controllers of the FX3U family, which has a unique speed for this PLC class, a significant memory size, high configuration flexibility, and advanced communication tools. These controllers combine in a single design: power supply, central processing unit, memory, built-in discrete input/output channels, RS-422 programming port. The number of built-in discrete I/O channels ranges from 16 to 128. If it is necessary to increase the number of channels, it is possible to connect additional I/O modules to the controller's internal high-speed bus. One of the most important design features of the PLC FX3U is the presence of a second expansion bus located on the left side of the controller and designed to connect additional adapter modules.

All controllers of this series have a built-in non-volatile program memory of 256 KB. This makes it possible to implement complex control algorithms and store a large amount of information in data registers.

Benefits of Mitsubishi Electric's new FX3U series of PLCs: Attractive price, high reliability, high performance in its class, configuration flexibility, up to 384 I/O channels, up to 128 analog I/O channels, advanced communications.

The communication controller ELSI-COM, developed by specialists from the Tomsk Scientific Research Institute of Electronic Systems, is designed to solve the problem of collecting information from various subsystems and routing information between subsystems. ELSI-COM is a specialized device designed to organize information exchange between equipment of automation and telemechanics systems using various interfaces. The controller allows, at minimal cost, to implement information exchange between several channels with different communication interfaces, to combine equipment of various manufacturers or types into a single system, and also to convert one protocol to another. ELSI-COM provides the user with the opportunity to work with the most common technological protocols and interfaces. The controller is designed for continuous unattended operation at technological facilities.

The SCADAPack controller, developed by the Canadian company Control Microsystems, combines a high-performance 32-bit processor, 16 MB flash, 4 MB CMOS, analog and digital I/O, extensive LAN and USB communication, and advanced power saving capabilities. . The SCADAPack PLC can be programmed both locally and remotely using ladder languages. For high-speed interaction with other equipment, the control uses an Ethernet adapter that supports ModBus/TCP, ModBus RTU/ASCII in UDP, DNP in TCP protocols. It is possible to supply the controller with an integrated wireless communication module operating at a frequency of 900 MHz or 2.4 GHz.

JSC "ZEiM" has developed a controller with a functionally decentralized architecture - KROSS-500 and a controller with a functionally and geographically decentralized architecture - TRASSA, designed to automate objects of various classes on homogeneous equipment - simple and complex, concentrated and distributed. A distinctive feature of these controllers is the presence of modules that autonomously and independently of the central processor perform not only input / output functions, but also various control functions programmed by the user. This significantly increases the reliability, survivability of the controller and the dynamics of the performance of individual functions, and also reduces the cost of systems.

The ThinkIO controller, developed by Contron, is a new, highly flexible and customizable control system. The small dimensions of the controller (thickness no more than 70 mm) ensure its installation in small-sized industrial switching cabinets. The new system consists of a DIN-rail mounted ThinkIO computer and Wago's modular I/O system. The ThinkIO controller is equipped with a 266 MHz Intel® PentiumR MMX compatible processor, a watchdog timer, standard communication interfaces for USB, two Fast Ethernet, RS-232 and industrial buses (Profibus, CAN and DeviceNet), a DVI digital graphics interface, and also with connectors for direct connection to the Wago I/O system. Ability to configure and manage the controller via the Internet and local network provided by the integrated software environment SOPH.I.A.

Modicon's Quantum series of powerful programmable controllers is the perfect platform for all automation tasks. With the Quantum controller's modular architecture, scalable from a single controller to a global automation system, it can handle the most demanding tasks across the entire enterprise. Quantum controllers are programmatically and also network-compatible with the younger series of controllers - Compact and Momentum, which allows you to build even more flexible and efficient control architectures. Quantum is easy to configure and operate, provides a wide range of architectures and modules, has thousands of installations worldwide, and has been proven in hundreds of applications.

The SIMATIC S7-200 family of programmable controllers from Siemens are designed to build relatively simple and cheap automatic control systems. They have high performance: high instruction execution speed and, as a result, a short program execution cycle time. Availability of high-speed counters external events, expanding the possible areas of application of controllers. Fast processing of interrupt requests. SIMATIC S7-200 controllers are highly versatile: the ability to expand the control system by connecting additional I / O modules. A powerful system of commands for fast and convenient processing of information in any practical application. Many additional features: PPI interface that supports programming, execution of human-machine interface maintenance procedures, serial data exchange with various equipment. Friendly STEP 7 Micro/Win and STEP 7 Micro/DOS programming packages. Three-level password protection of user programs. TD200 text display and a wide range of operator panels to create a user-friendly human-machine interface. SIMATIC S7-200 programmable controllers have been expanded with new types of CPUs: CPU 210, CPU 221, CPU 222 and CPU 224. Compared to their counterparts, the new CPU 22x CPUs are smaller, have more memory, have higher performance, can be programmed in FBD language.

Allen-Bradley is one of the world leaders in the development and production of highly reliable industrial controllers from MicroLogix microcontrollers to powerful PLC controllers. One of the most common controllers are SLC-500 (Small Logical Controller), which have a wide range of applications - from small autonomous to large distributed control systems. SLCs are good example modern programmable logic controller. In this graduation project, an Allen-Bradley SLC-500 microprocessor controller was used.

The SLC-500 controllers are available in fixed and modular designs. A modular controller is a chassis, a power supply, a processor module, and a set of I/O modules for an object, determined by the number of input and output signals. The modular programmable controllers of the SLC series include 12 processor modifications, more than 80 types of I/O modules, special modules, 4 chassis sizes for installing modules (4, 7, 10, 13 seats). Each CPU module can support up to 30 I/O modules in a system and up to 3 chassis.

3.2 Basic technical data of the SLC controller 5/04

In the developed automation system, the modular controller of the American company Allen Bradley SLC 5/04 was used, since its functions meet the requirements of the system being developed. Table 3.1 summarizes the characteristics of the SLC 5/04 controller.

Table 3.1 - Brief characteristics of SLC 5/04

Program memory
Additional memory	Up to 4K words
I/O capacity
Max. Chassis/I/O slot
Additional redundant memory
Programming	APS, RSLogix 500 A.I.
Instruction set
Execution time of bit instructions
Typical scan time	0.9 ms/K

The developed automation system contains the following signals:

discrete inputs - 158;

discrete outputs - 67;

analog inputs - 51.

The I&C table is presented in Appendix B.

3.3 Controller configuration

The controller contains:

CPU - 1747-L541 5/04;

chassis for 13 slots - 2 pcs.;

power supply 1746-P4 - 2 pcs.;

discrete input module (24V) 1746-IB32 - 3 pcs.;

discrete input module (220V) 1746-IM16 - 5 pcs.;

discrete output module (24V) 1746-OB32 - 1 pc.;

discrete output module (220V) 1746-OW16 - 4 pcs.;

analog input module 1746-NI16I - 3 pcs.

analog input module 1746-NR4 - 3 pcs.

The RTU table is presented in Appendix D.

The memory card is presented in Appendix D.

3.4 Controller Programming

The program controlling the automation system contains the following blocks:

main program;

analog module initialization subroutine;

subroutine for copying data from discrete sensors to the controller memory;

subroutine for processing analog and discrete signals;

PID instruction processing subroutine.

In the analog modules initialization subroutine (called only when the controller is first started or when it is rebooted), the configuration word is written.

1746 - NI16I class3 analog module initialization word configuration is shown in Table 3.2.

Table 3.2 - Initialization word for 1746 module - NI16I class3

Bits 15, 14, 13 are error status bits. If 0 is written in bit 13, then the value is greater than 20mA, if bit 14 is 0, then the value is less than 4mA, if the last three bits are 1, then there are no errors.

Controller programming is carried out using Ladder Logic language. This programming language is a ladder, each rung of which begins with one or more conditions and ends with an action. Moreover, this action will be executed only when the conditions preceding it are true. Each rung is called a "rank". The algorithm of the program is presented in Appendix E, and the listing of the program is in Appendix G.

3.5 Selecting the protocol for the exchange of information between the controller and the upper level of the process control system

The information collection and control system is designed to collect data on the state of technological parameters, control installations, auxiliary systems, pumping units, and provide service personnel with reliable information.

The structure of the SCADA system has two levels: the lower level - signals from sensors and the upper one - the operator's automated workplace.

The controller constantly reads information from the sensors, when the process parameters change or exceed the specified settings, it issues a message to the operator room, controls the operation of pumps, valves, regulators, etc.

Information from the sensor enters the module, after which the controller converts this value, compares it with the settings, and using the tag, the value is displayed on the operator's monitor.

To communicate with the controller, a 1748-KTX network adapter is used, designed to work with a DH-485 network using the DF1 protocol. The maximum network length is 4000 feet, the maximum data rate is 19.2 Kbps.

3.6 Operator interface

As software for the implementation of the upper level, we use RSView32, owned by Rockwell Software (USA)

When you log in and out of the surveillance program, you are prompted for a username and personal password. To organize communication with the upper level, a tag table was developed, presented in Appendix I. The operator interface consists of 11 graphic screens, including trends and alarms, the screen hierarchy is presented in Appendix K.

Operators and dispatchers receive the necessary information about the progress of the controlled process, as well as information about the state of the equipment by presenting it on the MMI screens presented in Appendix L. For easier perception of information when creating the interface, the following were used: graphs (trends), tables (signaling), animation, etc.

Display of technological parameters of the process: temperature, pressure, level, water cut, etc. must be done with a certain degree of precision. The minimum value of the quantity that the device can measure can be determined by the formula:

(3.1)

As an example, let's determine with what accuracy it is necessary to display the pressure in front of the valve 1e.

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7.1 General characteristics of control systems. Sensors and transducers

Automatic control is based on continuous and accurate measurement of input and output technological parameters of the enrichment process.

It is necessary to distinguish between the main output parameters of the process (or a specific machine), characterizing ultimate goal process, for example, qualitative and quantitative indicators of processed products, and intermediate (indirect) technological parameters that determine the conditions for the process, equipment operating modes. For example, for a coal cleaning process in a jigging machine, the main output parameters may be the yield and ash content of the products produced. At the same time, these indicators are affected by a number of intermediate factors, for example, the height and looseness of the bed in the jigging machine.

In addition, there are a number of parameters characterizing the technical condition of technological equipment. For example, the temperature of bearings of technological mechanisms; parameters of centralized liquid lubrication of bearings; condition of transshipment units and elements of flow-transport systems; the presence of material on the conveyor belt; the presence of metal objects on the conveyor belt, the levels of material and pulp in the tanks; duration of work and downtime of technological mechanisms, etc.

Of particular difficulty is the automatic on-line control of technological parameters that determine the characteristics of raw materials and enrichment products, such as ash content, material composition ores, the degree of opening of mineral grains, the granulometric and fractional composition of materials, the degree of oxidation of the grain surface, etc. These indicators are either controlled with insufficient accuracy or not controlled at all.

A large number of physical and chemical quantities that determine the modes of processing of raw materials are controlled with sufficient accuracy. These include the density and ionic composition of the pulp, volumetric and mass flow rates of process streams, reagents, fuel, air; levels of products in machines and apparatuses, ambient temperature, pressure and vacuum in apparatuses, humidity of products, etc.

Thus, the variety of technological parameters, their importance in the management of enrichment processes require the development of reliable control systems, where the on-line measurement of physical and chemical quantities is based on a variety of principles.

It should be noted that the reliability of the parameters control systems mainly determines the performance of automatic process control systems.

Automatic control systems serve as the main source of information in production management, including automated control systems and process control systems.

Sensors and transducers

The main element of automatic control systems, which determines the reliability and performance of the entire system, is a sensor that is in direct contact with the controlled environment.

A sensor is an element of automation that converts a controlled parameter into a signal suitable for entering it into a monitoring or control system.

A typical automatic control system generally includes a primary measuring transducer (sensor), a secondary transducer, an information (signal) transmission line, and a recording device (Fig. 7.1). Often, the control system has only a sensitive element, a transducer, an information transmission line and a secondary (recording) device.

The sensor, as a rule, contains a sensitive element that perceives the value of the measured parameter, and in some cases converts it into a signal convenient for remote transmission to the recording device, and, if necessary, to the control system.

An example of a sensing element would be the membrane of a differential pressure gauge that measures the pressure difference across an object. The movement of the membrane, caused by the force from the pressure difference, is converted by an additional element (converter) into an electrical signal that is easily transmitted to the recorder.

Another example of a sensor is a thermocouple, where the functions of a sensitive element and a transducer are combined, since an electrical signal proportional to the measured temperature appears at the cold ends of the thermocouple.

More details about the sensors of specific parameters will be described below.

Converters are classified into homogeneous and heterogeneous. The former have input and output values ​​that are identical in physical nature. For example, amplifiers, transformers, rectifiers - convert electrical quantities into electrical quantities with other parameters.

Among the heterogeneous, the largest group is made up of converters of non-electric quantities into electrical ones (thermocouples, thermistors, strain gauges, piezoelectric elements, etc.).

According to the type of output value, these converters are divided into two groups: generator ones, which have an active electrical value at the output - EMF, and parametric ones - with a passive output value in the form of R, L or C.

Displacement transducers. The most widely used are parametric transducers of mechanical displacement. These include R (resistor), L (inductive), and C (capacitive) transducers. These elements change the output value in proportion to the input displacement: electrical resistance R, inductance L and capacitance C (Fig. 7.2).

The inductive transducer can be made in the form of a coil with a tap from the midpoint and a plunger (core) moving inside.

The converters in question are usually connected to control systems using bridge circuits. A displacement transducer is connected to one of the arms of the bridge (Fig. 7.3 a). Then the output voltage (U out), taken from the tops bridge A-B, will change when moving the working element of the transducer and can be evaluated by the expression:

The supply voltage of the bridge (U pit) can be direct (at Z i =R i) or alternating (at Z i =1/(Cω) or Z i =Lω) current with frequency ω.

Thermistors, strain- and photoresistors can be connected to the bridge circuit with R elements, i.e. converters whose output signal is a change in active resistance R.

The widely used inductive converter is usually connected to an AC bridge circuit formed by a transformer (Fig. 7.3 b). The output voltage in this case is allocated to the resistor R, included in the diagonal of the bridge.

A special group is made up of widely used induction converters - differential transformer and ferro-dynamic (Fig. 7.4). These are generator converters.

The output signal (U out) of these converters is formed as an AC voltage, which eliminates the need for bridge circuits and additional converters.

The differential principle of generating an output signal in a transformer converter (Fig. 6.4 a) is based on the use of two secondary windings connected towards each other. Here, the output signal is the vector voltage difference that occurs in the secondary windings when the supply voltage U pit is applied, while the output voltage carries two information: the absolute value of the voltage is about the magnitude of the plunger movement, and the phase is the direction of its movement:

Ū out = Ū 1 – Ū 2 = kX in,

where k is the coefficient of proportionality;

X in - input signal (plunger movement).

The differential principle of generating the output signal doubles the sensitivity of the converter, since when the plunger moves, for example, upwards, the voltage in the upper winding (Ū 1) increases due to the increase in the transformation ratio, the voltage in the lower winding decreases by the same amount (Ū 2) .

Differential transformer converters are widely used in control and regulation systems due to their reliability and simplicity. They are placed in primary and secondary instruments for measuring pressure, flow, levels, etc.

More complex is the ferrodynamic transducers (PF) of angular displacements (Fig. 7.4 b and 7.5).

Here, in the air gap of the magnetic circuit (1), a cylindrical core (2) with a winding in the form of a frame is placed. The core is installed using cores and can be rotated through a small angle α in within ± 20 °. An alternating voltage of 12 - 60 V is applied to the excitation winding of the converter (w 1), as a result of which a magnetic flux arises that crosses the area of ​​\u200b\u200bthe frame (5). A current is induced in its winding, the voltage of which (Ū out), ceteris paribus, is proportional to the angle of rotation of the frame (α in), and the phase of the voltage changes when the frame is rotated in one direction or another from the neutral position (parallel to the magnetic flux).

The static characteristics of the PF converters are shown in fig. 7.6.

Characteristic 1 has a converter without bias winding (W cm). If the zero value of the output signal is to be obtained not on average, but in one of the extreme positions of the frame, the bias winding should be switched on in series with the frame.

In this case, the output signal is the sum of the voltages taken from the frame and the bias winding, which corresponds to a characteristic of 2 or 2 "if you change the connection of the bias winding to antiphase.

An important property of a ferrodynamic transducer is the ability to change the steepness of the characteristic. This is achieved by changing the value of the air gap (δ) between the fixed (3) and movable (4) plungers of the magnetic core, screwing or unscrewing the latter.

The considered properties of PF converters are used in the construction of relatively complex control systems with the implementation of the simplest computational operations.

General industrial sensors of physical quantities.

The efficiency of enrichment processes largely depends on the technological regimes, which in turn are determined by the values ​​of the parameters that affect these processes. The variety of enrichment processes causes a large number of technological parameters that require their control. To control some physical quantities, it is sufficient to have a standard sensor with a secondary device (for example, a thermocouple - an automatic potentiometer), for others, additional devices and converters are required (density meters, flow meters, ash meters, etc.).

Among a large number of industrial sensors, one can single out sensors that are widely used in various industries as independent sources of information and as components of more complex sensors.

In this subsection, we consider the simplest general industrial sensors of physical quantities.

Temperature sensors. The control of thermal modes of operation of boilers, dryers, and some friction units of machines makes it possible to obtain important information necessary to control the operation of these objects.

Manometric thermometers. This device includes a sensitive element (thermal bulb) and an indicating device connected by a capillary tube and filled with a working substance. The principle of operation is based on the change in the pressure of the working substance in a closed thermometer system depending on the temperature.

Depending on the state of aggregation of the working substance, liquid (mercury, xylene, alcohols), gas (nitrogen, helium) and steam (saturated steam of a low-boiling liquid) manometric thermometers are distinguished.

The pressure of the working substance is fixed by a manometric element - a tubular spring, which unwinds with increasing pressure in a closed system.

Depending on the type of working substance of the thermometer, the temperature measurement limits range from -50 ° to +1300 ° C. The devices can be equipped with signal contacts, a recording device.

Thermistors (thermoresistors). The principle of operation is based on the property of metals or semiconductors ( thermistors) change its electrical resistance with temperature. This dependence for thermistors has the form:

where R 0 – conductor resistance at T 0 \u003d 293 0 K;

α T - temperature coefficient of resistance

Sensitive metal elements are made in the form of wire coils or spirals, mainly from two metals - copper (for low temperatures - up to 180 ° C) and platinum (from -250 ° to 1300 ° C), placed in a metal protective casing.

To register the controlled temperature, the thermistor, as a primary sensor, is connected to an automatic AC bridge (secondary device), this issue will be discussed below.

In dynamic terms, thermistors can be represented as a first-order aperiodic link with a transfer function W(p)=k/(Tp+1), if the time constant of the sensor ( T) is much less than the time constant of the object of regulation (control), it is permissible to accept this element as a proportional link.

Thermocouples. Thermoelectric thermometers (thermocouples) are usually used to measure temperatures in large ranges and above 1000 ° C.

The principle of operation of thermocouples is based on the effect of the occurrence of DC EMF at the free (cold) ends of two dissimilar soldered conductors (hot junction), provided that the temperature of the cold ends differs from the temperature of the junction. The value of the EMF is proportional to the difference between these temperatures, and the value and range of measured temperatures depends on the material of the electrodes. Electrodes with porcelain beads strung on them are placed in protective fittings.

The connection of thermocouples to the recording device is made by special thermoelectrode wires. A millivoltmeter with a certain calibration or an automatic DC bridge (potentiometer) can be used as a recording device.

When calculating control systems, thermocouples can be represented, like thermistors, as a first-order aperiodic link or proportional.

The industry produces various types of thermocouples (Table 7.1).

Table 7.1 Characteristics of thermocouples

Pressure Sensors. Pressure (vacuum) and differential pressure sensors received the widest application in the mining and processing industry, both as general industrial sensors and as components of more complex systems for monitoring such parameters as pulp density, media consumption, liquid media level, suspension viscosity, etc.

Devices for measuring excess pressure are called manometers or pressure gauges, for measuring vacuum pressure (below atmospheric, vacuum) - with vacuum gauges or draft gauges, for simultaneous measurement of excess and vacuum pressure - with pressure and vacuum gauges or thrust gauges.

The most widespread are spring-type sensors (deformation) with elastic sensitive elements in the form of a manometric spring (Fig. 7.7 a), a flexible membrane (Fig. 7.7 b) and a flexible bellows.

.

To transfer readings to a recording device, a displacement transducer can be built into the pressure gauges. The figure shows inductive-transformer transducers (2), the plungers of which are connected to the sensitive elements (1 and 2).

Devices for measuring the difference between two pressures (differential) are called differential pressure gauges or differential pressure gauges (Fig. 7.8). Here, pressure acts on the sensitive element from two sides, these devices have two inlet fittings for supplying more (+ P) and less (-P) pressure.

Differential pressure gauges can be divided into two main groups: liquid and spring. According to the type of sensitive element, among the spring ones, the most common are membrane (Fig. 7.8a), bellows (Fig. 7.8 b), among liquid - bell (Fig. 7.8 c).

The membrane block (Fig. 7.8 a) is usually filled with distilled water.

Bell differential manometers, in which the sensing element is a bell partially immersed upside down in transformer oil, are the most sensitive. They are used to measure small differential pressures between 0 and 400 Pa, e.g. to monitor vacuum in the furnaces of drying and boiler installations.

The considered differential pressure gauges are scaleless, the registration of the controlled parameter is carried out by secondary devices, which receive an electrical signal from the corresponding displacement transducers.

Sensors of mechanical forces. These sensors include sensors containing an elastic element and a displacement transducer, tensometric, piezoelectric and a number of others (Fig. 7.9).

The principle of operation of these sensors is clear from the figure. Note that a sensor with an elastic element can work with a secondary device - an AC compensator, a strain gauge sensor - with an AC bridge, a piezometric sensor - with a DC bridge. This issue will be discussed in more detail in subsequent sections.

The strain gauge is a substrate on which several turns of a thin wire (special alloy) or metal foil are glued, as shown in Fig. 7.9b. The sensor is glued to the sensing element, which perceives the load F, with the orientation of the long axis of the sensor along the line of action of the controlled force. This element can be any structure that is under the influence of the force F and operates within the limits of elastic deformation. The load cell is also subjected to the same deformation, while the sensor conductor is lengthened or shortened along the long axis of its installation. The latter leads to a change in its ohmic resistance according to the formula R=ρl/S known from electrical engineering.

We add here that the considered sensors can be used to control the performance of belt conveyors (Fig. 7.10 a), measure the mass of vehicles (cars, railway cars, Fig. 7.10 b), the mass of material in bunkers, etc.

Evaluation of conveyor performance is based on weighing a certain section of the belt loaded with material at a constant speed of its movement. The vertical movement of the weighing platform (2) mounted on elastic links, caused by the mass of material on the tape, is transmitted to the induction-transformer converter (ITP) plunger, which generates information to the secondary device (Uout).

For weighing railway cars, loaded vehicles, the weighing platform (4) rests on strain gauge blocks (5), which are metal supports with glued strain gauges that experience elastic deformation depending on the weight of the weighing object.