PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems

The research object of this paper is distributed industrial control systems - one class of control systems that used for supporting for broad spectrum of technical systems. The purpose of this paper is design and analysis of approaches for creating and realization of distributed industrial control systems elements. According to State system industrial devises and automation tools requirements such systems can be considered as a complex of automation and control subsystem and collection, transmission and distribution subsystem. For each subsystem a features of functioning and realization methods are considered, examples are shown. The specification of elements functioning for each form subsystems is performed. The object and subject of research for this paper are defined. The component and communication models of subsystems are created and analyzed and their similarities and differences are indicated. It allowed suggesting the common approaches to providing parameters and characteristics of its basic elements. The typical structure of the distributed information and control system is presented, the objects of management and control are highlighted, the processes of collecting, transmitting and distributing information between devices of different levels of administration are analyzed. The analysis of design methods of control systems elements is done; the requirements for their practical realization are formulated. The approach to providing of preset operation and technical indicators of control systems elements. It based on using technical diagnostics methods, ways to improve the reliability of data transmission and decision-making algorithms for the results of processing diagnostic information. A formal formulation of the problem of ensuring the quantitative and qualitative indicators (reliability, testability, transmission reliability) of the control systems elements has been completed. The results of implementation of offered approaches are shown; the directions of next research are defined.

One of the main reasons for the increase in the damage of single-phase cable lines made by an electric cable of a new generation, using cross-linked polyethylene as an insulation, is the wrong choice of the screen section and its grounding schemes in terms of accounting for induced currents and the power losses caused by them. In the article considered the possibility of solving actual problems of study of the electrical screen mode single-phase power cables with XLPE insulation with over-Zeleniy cable shield at both ends. The scheme of substitution is offered and theoretical research of features of current flow in the cable screen and the earth is executed, and also the analysis of losses of active power in the screen taking into account resistance of grounding conductors. The calculated ratios for determining the current in the "earth channel" and the screen of the power cable of the new generation with insulation made of cross-linked polyethylene are obtained. The interrelation between the currents of cable core, cable screen and "earth channel"is established. The results of a computational experiment to determine the values of the "earth-Lee" current for cables with cross-linked polyethylene insulation with different screen cross-sections are presented. The estimation of active power losses in the ground, core and cable screen at grounding on both sides and overvoltage on the cable screen at one-way grounding is performed. It is shown that for the implementation of measures to optimize energy losses in power supply systems of industrial enterprises it is advisable to build a single-phase cable line with two cables insulation made of cross-linked polyethylene. At the same time, the implementation of a single-phase two-wire power line with wires of different cross sections due to an increase in electricity losses is impractical.

The article presents the basic requirements for the converters of the switched-reluctance motors (SRM): the possibility of implementing positive, negative and zero circuits, saving energy accumulated in the winding phase of the switched-reluctance drive (SRD) for further use, ensuring the operation of the phases with overlap, fault tolerance. The modes of operation and advantages of the classical asymmetric half-bridge сonverter circuit SRM containing a source, two transistor switches, two reverse diodes and a capacitor are presented. A new circuit solution for the сonverter is proposed. A single-key circuit is considered, which contains two independent galvanically isolated DC voltage sources, two capacitors, a diode, a semiconductor key and a phase stator winding of a SRM divided into two half-windings. The mathematical model is presented and simulation in the environment of MatLab/Simulink, classical and single-key power supply circuit of the switched-reluctance machine (SRM) phase is carried out. Comparative graphs of instantaneous values of currents in the winding and electromagnetic moment, which differ in amplitude by two times the values of currents and voltages on a semiconductor key and diode, are obtained for two circuits. The new scheme, while maintaining the advantages of the classical scheme, allows to reduce the number of power semiconductor elements and, consequently, the cost of the converter, and also allows you to implement a separate power supply of coils SRМ. Power supply scheme of SRD with one power key element (transistor) is proposed for switching each phase. While the most commonly used at present is the half-bridge power circuit SRM, which has two key elements. Reducing the number of relatively expensive power elements will reduce the cost of the converter and simplify its power part. The main application area of the new circuit solution is determined. Since the single-key circuit requires two sources, it is most convenient for electric drives powered from autonomous electric power sources, for example, electric vehicles, robots, aircraft and underwater vehicles of drive mechanisms, as well as electric drives operating in places remote from the centralized power supply.

The change-over to the 4th generation heat supply networks, according to which residual heat or the heat that is given out as a result of other activities is used, places high requirements to control systems in heat supply networks and to the quality of decisions. The paper considers the issues of selecting temperature rates for heat supply operation by the joint use of boiler plant steam for technological process and the heating of a group of buildings. The paper is aimed at building a model that allows to make decisions about the capacity of heat production and energy feed scheme for heat supply in a group of buildings by steam heating and in the conditions of parallel use of this energy in production process. In order for the set goal to be achieved, a performance curve has been built for heat supply system and the algorithm for managerial decision making has been worked out, correspondingly, which allow to minimize heat-transfer agent temperature deviations from target temperature in the conditions of changed ambience temperature. The performance curve was obtained on the base of statistical data. The use of the suggested approach helped not only minimize the deviations of heat-transfer agent temperature value from the target one, but also after being verified on the base of retrospective data demonstrated the average saving of energy of no less than 30 Gcal/heating period. Besides, the use of ambience temperature forecast data helped obtain a smooth change in equipment performance mode that will provide additional saving and will reduce the wearing of equipment. The proposed approach does not place restrictions on the type of equipment used and the structure of heat supply system.

The article studies the characteristics of an information control network with a random multiple access algorithm with carrier control and collision avoidance by predicting the network load of the predictive p-persistent CSMA channel. A significant advantage of the algorithm in comparison with other algorithms of the class of random multiple access is the dynamic adaptability of the transmission persistence level to the channel load. This is achieved using an advanced mechanism for predicting the expected network load for each data transfer cycle. The result is a decrease in channel access time at low load and a reduced likelihood of data collisions at high load. The algorithm is widely used in fieldbus networks, including the sensor and industrial networks of LonWorks and BacNet. A literary review shows the interest of the world community in the application of the algorithm, for which research and modernization of its mechanisms are actively conducted. The purpose of this work is to study the influence of the law of the distribution of the number of slots of competition for access to a channel on the probabilistic and temporal characteristics of data transmission in a network with the slot access algorithm studied. The paper presents a brief description of the principles of operation of the studied access algorithm and describes the structure of the developed and used model in the simulation environment AnyLogic. The necessary simulation experiments of the functioning of the network with the services of reliable and unreliable message delivery were carried out using three different laws for choosing the slots of rivalry (uniform, normal, exponential). The analysis of the obtained characteristics of the network operation is made and conclusions are made about the impact of the laws of choice of access slots on the duration of transmission and the probability of data loss during various network channel loads and delivery services. Recommendations are formulated on the expediency of applying various laws for choosing access slots.

A method of the mill load degreeoptimization in cement production to increase its efficiency is considered.This problem has many obstacles to solvebecause the quality of grinding and the consumption of resources depend on many factors that present great difficulties in their measurement and forecasting. Reliable measurement of the influencing factors necessary to determine the optimal combination of the volume of the ball load of grinding and the amount of solids necessary to reduce the particle size of the charge with a minimum specific energy consumption. This paper describes an application for the operational management of a closed-loop cement mill that uses prediction technology. A controllerbased on this method, should work in real time and reflect the current state of the grinding process. Decision making for this operational management belongs to the class of multi-criteria tasks. The paper proposes a decision-making method based on the set of permissible technical conditions imposed on the grinding process. Such a formulation of the problem is generally contradictory. The paper proposes an approach to solving this problem based on determining the maximum number of joint weighted technical conditions imposed on the process. This approach allows to organize an interactive procedure for selecting a feasible solution for the operational management of the grinding process. The control optimization for the ball mills allows to increase mill productivity up 3-5 % and reduce specific power consumption to 2-4 %.

The methods of diagnostics of electric machines are gaining immense popularity and significance. Not all enterprises can continuously upgrade their equipment due to lack of funds. They are forced to reduce the budget for re-equipment and use the machines that long ago need repair. Any electric machine, even with proper care, requires repair. If you do not perform repairs on time, then there may be emergencies that are life-threatening for maintenance personnel. Solving this problem, they resort to a constant assessment of the technical condition of the machine. The article deals with the implementation of one of the methods of such the estimation, carried out by spectral analysis of the stator current of a synchronous machine. The instantaneous values of the stator currents are decomposed into a harmonic series by means of the coefficients of the Fourier series. Analysis of the spectrum allows us to state that any additional harmonic causes a clear fault in the machine. This approach is as much more objective than other methods. The advantage of this technique is that it was already tested on an asynchronous machine and produced good results. The synchronous turbine generator of the TTK-50-2U3P series was selected for the study.