Automated method of calculation of parameters for non-traditional heating technologies and conditioning of buildings

Purpose. Develop an automated method for calculating parameters for heat pump systems for heating, air conditioning and hot water supply, designed for use in domestic conditions with non-standard heat transfer flows. Methodology. Mathematical modeling of thermodynamic processes occurring in heating, air conditioning and hot water supply systems. Findings. The automated method of calculating the parameters of non-traditional technology, which uses standard heat pump equipment of the water heating system for the cooling mode of the air in the warm period of the year, and the discharge of heat dissipated into the ground, was substantiated and developed; and for the needs of hot water supply heat pump air-liquid, acting as a high-speed water heater. The estimation of technologies of the thermal energy utilization in buildings developed earlier by authors is executed. The first technology involved the use of a heat pump and heat accumulator scheme in the cold season, and halved the consumption of conventional fuel compared to a gas column for hot water at the same facility. The second technology involved heat recovery with the help of a heat accumulator in a complex system of air conditioning and hot water supply in the warm period, which saves from 74 to 82% of conventional fuel compared to the scheme with boiler and air conditioner without heat accumulator. Critical conclusions were drawn about the need to use additional dimensional equipment for these technologies and the excess amount of hot water received. Possibilities of realization of such scheme were analyzed. Analytically substantiated recommendations on the design (ribbing of heat exchange surfaces) of heating devices and parameters of their operating modes in the cold and warm periods of the year were given. The condition of invariance of heat exchange areas of heating devices and basic water consumption in the heating system was fulfilled. The need to regulate the air conditioning regime by changing the water flow in the system to maintain a constant indoor air temperature with fluctuations in outdoor air temperature was substantiated. Originality. For the first time, attention is paid to the study of non-traditional methods of using heat pump heating for heating, air conditioning and hot water supply of residential premises. The automated method for determining rational parameters for these technologies was developed. Practical value. The automated method of forming the control dependence of the mass flow of water in the system on the outside air temperature on the condition of constancy of the set comfortable indoor air temperature was developed. The use of air-liquid heat pump for hot water supply in the warm period was analyzed, a high energy conversion factor was noted (14 ... 22). The savings of conventional fuel from the application of the considered technology from 13% to 18% in comparison with the technology using a heat accumulator were substantiated.

Modeling of welding arc power supply diagrams in Matlab / Simulink

Purpose. Creation of virtual blocks and simulation laboratory stands for the study and comprehensive research of the dynamic properties of welding power supplies. Methodology. Review of literary sources on the subject, simulation modeling of electromagnetic processes in the MATLAB software environment, comparative analysis of obtained and available data. Findings. The comparative analysis of means of modeling of power sources of a welding arc is executed. One of the main parameters by which the environments were compared is functionality. Among the considered simulators, Simulink of the MATLAB software environment is the most effective one in the considered systems modeling. Using special features, its user can not only simulate, but also analyze the operation of the over time installation. Mathematical and functional models of welding arc power supplies were built using SimPowerSystems elements and blocks from the Simulink library with the involvement of the MATLAB system itself, which significantly expands the possibilities for such systems modeling. Mathematization of certain processes to some extent shows the level of reliability of the results and the degree of their scientific development. The developed models act as a laboratory, which allows you to set and explore any modes and characteristics. Numerical experiments and comparative analysis of numerical and field experiments are given. Experimental verification of the obtained results on specific examples showed the relevance of the problem and the correctness of its solution. Further research is related to the expansion of the range of simulated power sources of the electric arc, a comprehensive study of their dynamic properties and basic characteristics, experimental verification of the developed models, as well as comparative analysis and development of recommendations for model improvement. Originality. The method of circuit modeling of general-purpose electrical and electronic circuits was further developed by extending it to a new class of objects - the power supply system of electrical installations. Practical value. Construction of mathematical and functional models of complex systems with the involvement of MATLAB allows to take into account their main features, significantly expands the possibilities for modeling, study and research of power supplies. Based on the proposed approach, simulation laboratory stands of specific power supplies were developed and built, which allow to set and study any modes and characteristics.

Physical modeling of unsteady electromagnetic processes in power transformer under sharp load fluctuations

Purpose. To develop and experimentally confirm the method of physical modeling of non-stationary electromagnetic processes in a powerful power transformer operating under variable loads by combining similarity criteria and equivalence coefficients. Methodology. Theoretical provisions of mathematical and computer modeling, theoretical electrical engineering were used in the research, as well as the theory of experiment with the application of equivalence coefficients. Findings. Methods of experimental research were developed, which include the formation and registration of a set of external and internal parameters of physical models, prototypes and real equipment. Criteria for similarity of nonstationary electromagnetic processes excited by sharply changing scattering fields in special purpose power transformers are obtained. . Originality. The theory and practice of physical modeling, as well as the similarity theory applied to unsteady electromagnetic processes in powerful transformer equipment for special purposes were further developed. A set of distinctive features of test conditions and their registration were formed. Practical value. Application of physical modeling of unsteady electromagnetic processes at the design and manufacture stages of power transformers for power supply systems of electric arc furnaces, rolling mill drives, etc., as well as during the refinement of general-purpose power transformers.

Specific standards of energy consumption in the problem of controlling its use efficiency

Purpose. Analysis of the existing methods of specific energy consumption standardization and determination of the method acceptable for the standardization in conditions of transient structural and regime changes in energy consumption at a modern industrial enterprise. Methodology. Analysis of the existing methods of specific energy consumption standardization, identification of their disadvantages and advantages. Comparison of the possibilities of these methods with the requirements for the specific energy consumption standardization in modern production. Findings. Emphasis is focused on the significant dependence between reliability of the results of energy efficiency control of the production process (savings or overconsumption of energy) and the accuracy of the calculation of specific norms of energy consumption. The dependence between the assessments of the enterprise’s staff energy saving activity and the achieved accuracy of energy consumption standardization is determined. It is highlighted that in energy efficiency standardization practice, the existing methods are focused on the production conditions, where their benefits are fully revealed. It is proved that due to the increased accuracy of the standardization, efficiency of obtaining and processing information, the statistical method is the most acceptable for the conditions of transient structural and regime changes in the power consumption of the object. Prospects for improving the method of energy efficiency control are described. Originality. For the first time, the use of the statistical method of specific energy consumption standardization in the system of energy efficiency control of production processes with rapid structural and regime changes in energy consumption of the object is proposed. Practical value is to determine an acceptable method of specific energy consumption standardization in the conditions of modern industrial production, as well as ways to improve it.

Polynomial approximation of dynamic signals of single platform railway scales

Purpose. Obtaining an approximating function (or a system of approximating equations), which, with a minimum error, will make approximations to the available data on a train of railway objects through 1 platform scales. Methodology. To solve this problem, numerical methods are used, namely, the approximation by polynomial functions of the nth order. The experimental data on the basis of which the experiments were carried out were obtained from the weighing and identification system of wagon in motion on a single platform scale. The approximation process is automated using a program written in the Python programming language in which the polyPit and polyid functions of the numPy library are used to obtain the polynomial coefficients. Findings. Due to the use of polynomial approximation in data processing from tensometric railroad weighing systems, it was possible to obtain a system of linear equations that, with minimal error, restored the experimental data that were obtained from the existing system of the Severny GOK: Metinvest enterprise. When normalizing the readings of the sensors from conventional units, obtained from the summing box to the range of values [0; 1] it became possible, in percentage terms, to describe a railway object. This makes it possible to avoid the dependence of the final results on the travel speed of the carriage or locomotive, which leads to an increase in the accuracy of the identification of cars in the rolling stock due to the use of the percentage of the axles staying on the weighing platform (approach / exit). It became possible to determine the type of carriage with the same number of axles, but different characteristics of the center space and the base of the rolling stock. Originality. The novelty is to obtain a general method of approximation of experimental data of the passage of wagons through a single-platform scales, which can be used to train intelligent systems and generate close to real data of the passage of a car (due to the imposition of noise, etc.). Practical value. Improving the accuracy and speed of the carriage identification as a whole, which reduces the plant downtime, contributes to an increase in the number of weighed and identified moving objects, as well as the ability to identify the type of carriage with the same number of axles in the train. The methods presented in the work can be used both for identification and for tasks, the end result of which is the classification of input data (neural networks, etc.).

Vector control system of electric drive of grain machine conveyor

Purpose. Synthesis of an automatic control system for an asynchronous electric drive of a grain thrower conveyor based on a frequency converter with vector control. Methodology. The research was carried out using methods of mathematical modeling of an electric drive; using methods of tuning optimization and regulator synthesis. The technique of synthesis of vector control systems is based on the representation of a non-stationary multi-connected object, which is an AC machine, in the form of a set of stationary subobjects with linear links in the main control channels. Findings. The study of the work of the subordinate regulation system, which implements the principles of vector control, oriented along the vector of the rotor flux linkage, has been carried out. The modeling of the processes of AM excitation, AM start-up at idle speed, nominal load surge, speed reduction has been carried out. It was found that the synthesized system is characterized by good quality indicators. The overshoot at start does not exceed 5%, the regulation time is 0.4 s, the torque limitation is carried out at a predetermined level. It has been proven that oscillatory processes in transient modes with significant torque surges with classical settings of loop regulators can be compensated by introducing artificial cross-links into the control part of the electric drive. Originality. A system of subordinate regulation of the blood pressure of the grain thrower trimmer conveyor has been implemented to set the speed of the grain flow with the aim of throwing grain at a given distance by creating an appropriate ballistic flight trajectory, which ensures a reduction in losses from damage to grain. Practical value. The structure of the vector control system of a frequency-controlled asynchronous electric drive with additional compensating cross-connections between active and reactive energy control channels is proposed to improve the quality indicators of the system.

Methodology for selecting the rated parameters of power transformers in the town’s electrical distribution networks in settlements

Purpose. To substantiate a technique of a choice of nominal power of power transformers for increase of their use efficiency in distributive electric networks of the cities Methods. Analytical processing of statistical data. Findings. The paper solves the problem of efficient use of the installed power of transformers, their rational choice in the design of urban electrical networks. It was found that the choice of transformers according to classical methods causes a significant error and an overestimation of the rated power at the design stage. The method of reducing this error was developed for selecting the power of transformers of urban electrical networks. This method takes into account the predicted indicators of the operating modes of the equipment, the type of consumers, the load capacity of the equipment, the parameters of the operating mode and the environment, constant heating time of existing types of transformers that can be accepted for installation, the appropriate level of reactive load compensation. Originality The scientific novelty lies in the development of the method for selecting the rated power of power transformers 6 (20) /0.4 kV urban distribution networks by comprehensive consideration of the parameters of typical consumers and their actual structure, which will effectively use transformer equipment for load capacity during the regulated period of their operation. Practical value. The obtained results show the increase in the efficiency of capital and operating costs by selecting a rational rated power of distribution transformers 6 (20) / 0.4 kV with ensuring the effective use of their load capacity in the conditions of electric grids of cities.

Subsystem of sample processing of active and reactive power of transformer substation

Purpose. Apply statistical analysis to the volumetric samples of electricity consumption parameters to reduce the amount of network node capacity that will be stored. Methodology. Using the statistical data methods processing in the graphical programming system LabVIEW. Findings. Electricity is one of the energy types, the generation volume, transportation, distribution and use of which is constantly growing. At all these stages, the control of the change rate parameters of electrical energy – power occurs. Power is characterized by certain parameters that are subject to continuous monitoring. The change capacity in the conditions of industrial enterprises has a complex character with certain stochastic components. The need to record detailed information causes an increase in the data amount to be stored. As a result, there is a processing data problem on electric energy volumes and electric power parameters with reduction data volume and informativeness preservation. Based on the statistical normal distribution concept, in the graphical programming environment the data processing subsystem on sampling intervals of active and reactive powers of low voltage section the step-down substation is constructed. Using the indicators of the characteristics of the normal distribution of active and reactive power, the analysis of their semi-daily samples was performed. Selected intervals at which the indicators of normal distribution differ significantly, which allowed to form conclusions about the presence of modes close to idling Originality. It is established that due to the difficulty covering long time periods under the fixing condition data on electric power parameters, there is a dilemma regarding the resulting information amount and its detailing, to avoid information loss, a procedure based on the law of normal data sampling is the resulting data to be stored, with the possibility recording significant deviations in terms of excess and sample asymmetry. Practical value. Applying the proposed method in the monitoring system for long-term monitoring electrical power parameters, it is possible to reduce significantly the amount of data during the transmission basic information, power level and range, and, if necessary, use additional information about changes in observation intervals expressed through excess and asymmetry.

Laboratory stand with wireless interface for investigation of automatic control systems of dc electric drives

Purpose. Development of a laboratory stand with a wireless interface for the study and research of automatic control systems for DC electric drives. Methodology. Physical experiment on the developed laboratory bench, computer modelling, calculation and analytical methods. Findings. The study considered and analyzed the advantages and disadvantages of existing developments of laboratory stands with virtual and remote components, the possibility of organizing a wireless interface, taking into account cost-effectiveness, mobility, reliability and simplicity, as well as the possibility of using as a training stand. The connection of the stand by means of USB and Wi-Fi is developed. The STM32F103C8T6 microcontroller is used for the power switch and the automatic control system. The interface part consists of a NodeMCU board, a MicroSD card module, an interface control unit, a 16x2 LCD and an I2C converter. The UART-USB interface is used for information transfer and programming of the stand. The possibility of current remote transmission of information about the modes and parameters of the engine to a computer with a browser output by installing the Wi-Fi module ESP8266MOD. A closed system of automatic DC motor control with PID current regulators and EMF has been developed. Experiments were performed with a pulse and smooth increase in motor speed and variation of the components of the PID controllers using the control panel of the laboratory stand. All graphs of the results of the experiment were obtained on a web page with a fixed IP address in the browser via Wi-Fi. Originality. The structure of the remote monitoring and control system based on hardware and software combination of telecommunication and measuring systems is proposed and developed, which differs from the existing ones by the presence of current wireless transmission of information, which allows to remotely receive research data of automatic DC motor control systems. Practical value. The developed laboratory stand with the wireless interface allows to receive and store experimental data on parameters of the investigated engine in real time remotely.

Development of ideas about "bias current"

Purpose. In electrical engineering, radio engineering, such concepts as charge, electric field, magnetic field, electromagnetic field, direct electric current, alternating current are used. These abstract concepts reflect certain real physical phenomena. For example, current is understood as the directed movement of electric charges. However, there is also a conditionally abstract concept of "bias current", which was introduced by Maxwell to explain the passage of current through a section of capacitor where there are no charges. The purpose of the article is to reveal the substantive meaning of this term and to explain the real mechanism of current flow in an electric circuit. Methodology. Analysis of the phenomenon is performed on the basis of such traditional concepts as charge, electric field, magnetic field, electromagnetic field, direct electric current, alternating current. Analysis of the contradiction between the concept of current as a directed movement of charges and the concept of "bias current" as a current without charges is presented. Theoretical coordination of the "bias current "concepts and current as a directed motion of charges is done. Findings. It is shown that for all sections of a closed electric circuit, the definition of current as a directed movement of charges is valid only for direct current, when the charges are actually moving in all sections of the circuit. In the circuit with the capacitor, direct current does not flow, because there are no charges in the gap between the plates of the capacitor. However, alternating current occurs, at the moment when the circuit is closed. In the area of the conductor there is a directed movement of charges and the cause of the movement is an electric field, which is variable and occurs together with the alternating magnetic field in all parts of the circuit, including the part of the capacitor where there are no charges. It is shown that in general the concept of current as a directed motion of charges is correct, but conditionally abstract, because in fact the root cause is what is called an electromagnetic field. The concept of bias current is a conditionally abstract expression of the electromagnetic field. Originality. The novelty is that it is possible to understand adequately and non-abstractly the processes that occur in an electric circuit during the passage of current, that no current creates an electric field around the conductor on which charges move, and vice versa, alternating electric field leads to charges ,which are in the conductor areas. Practical value. Understanding the real essence of the term makes it possible to assess correctly the processes occurring in the electrical circuit; gives the answer whether the movement of charges occurs gradually or immediately around the circle when connecting an e.r.s. and closing the circuit. This understanding gives you an idea of what happens when the capacitor electrodes are connected to an e.r.s. and why do the electrons in a conductor come in a directed motion, what is the nature of the force acting on the electrons.