Electrical Engineering and Power Engineering

Operation of autonomous electromechanical converters of low and medium power

M.A. Kovalenko — 2025-04-30

Purpose. To assess the reliability of operation of low and medium power electromechanical converters based on real experience in operating such systems.

Methodology. Statistical analysis methods, classical calculation methods for synchronous salient pole generators with electromagnetic excitation.

Findings. An analysis of failure statistics of autonomous electromechanical converters of small and medium power was carried out. The results obtained emphasize the need to implement generator condition monitoring systems for early detection of malfunctions. Regular diagnostics and load control will help prevent critical breakdowns and increase the service life of the equipment. The collected statistical data can be used to develop effective preventive measures, improve maintenance instructions and optimize generator operating modes. Further research can be aimed at developing algorithms for automatic load distribution between phases, improving protection systems and increasing the reliability of insulating materials. An analysis of the failure statistics of diesel and gasoline generators showed that electrical breakdowns account for 51% of cases, and mechanical ones - 49%. This indicates an approximately even distribution between the two categories of failures, which indicates the need for a comprehensive approach to maintenance and diagnostics. When using these installations for military purposes, the balance of failures shifts: mechanical failures: 75-85%, electrical failures: 15-25%. Among electrical failures, the most common are damage to the stator windings due to load asymmetry, failure of voltage regulators, malfunctions of the battery system and violations of the insulation of the electrical wiring. Mechanical failures are most often associated with wear of the piston group, insufficient lubrication, engine overheating due to malfunctions of the cooling system and malfunctions in the fuel system.

Originality. A detailed generalization of the experience of operating autonomous electromechanical converters in real conditions was carried out, which allowed us to establish the regularities of their operation, identify typical problems and develop recommendations for their elimination. The methods for assessing the efficiency of autonomous electromechanical converters proposed in the study can be used for further modernization of existing systems, as well as for creating new highly efficient autonomous power generating units.

Practical value. The results of the study have practical value for engineers, users and manufacturers of electromechanical equipment. The results obtained can be used to improve the efficiency and reliability of autonomous power systems operating in various conditions. In particular, it is possible to reduce maintenance costs, improve energy efficiency and extend the service life of the equipment. The results obtained can be used in the development of recommendations for the selection, modernization and diagnostics of autonomous electromechanical installations.

Features of minimizing total electrical losses in high-voltage electromechanical systems for stationary industrial fan installations

A.V. Synetskyi — 2025-04-30

Purpose. Conduct a study of commutation processes and develop a methodology for determining the switching frequency of semiconductor elements in the converter for high-voltage electromechanical systems to minimize electrical losses during their operation with fan loads.

Methodology. Methods of multi-criteria and single-criteria optimization for finding the optimal values of electrical losses in an electromechanical system, methods for solving first-order differential equation systems, and analytical methods.

Findings. To improve the energy efficiency of a high-voltage electromechanical system for stationary industrial fan installations without modifying their structural design, the level of total losses has been assessed. A target function has been constructed to represent the dependence of total losses in the electric drive on the switching frequency of power switches and the harmonic distortion coefficients of the stator and rotor currents in a high-voltage wound-rotor asynchronous motor. Through approximation, a generating dependence of the switching frequency of the converter’s power switches on the harmonic distortion coefficient of the stator and rotor currents of the asynchronous motor has been established. The target function, initially dependent on three variables, has been transformed into a function of a single variable. Simulation modeling of electromagnetic and energy processes in the high-voltage electromechanical system has been conducted to evaluate total loss levels. A comparative analysis has been performed, confirming the adequacy of the obtained analytical expression for determining the optimal switching frequency of the converter’s power elements under the condition of minimizing losses in the high-voltage electromechanical system, with results validated through simulation.

Originality. A study of commutation processes in the power elements of the converter, which is part of the high-voltage electromechanical system, has been conducted. More precise analytical dependencies have been obtained, allowing for the determination of the main and commutation losses in the power elements of the converter for the high-voltage electromechanical system.

Practical value. A methodology for determining the optimal switching frequency of the semiconductor elements in the converter, which is part of the high-voltage electromechanical system, has been proposed. The calculation error of the optimal switching frequency of the semiconductor elements, obtained analytically, does not exceed 3.5% compared to the results obtained through simulation. The proposed methodology can be applied to minimizing losses in high-voltage electromechanical drive systems for both AC and DC applications used in various industrial mechanisms.

Automation of studies of pulsed current generators based on the topological-isomorphic model

N. І. Siddelev — 2025-04-30

Purpose. To evaluate the real usefulness of the topological-isomorphic model of powerful electromagnetic circuits on the example of the study of pulse current generators.

Methodology. Nodal potential method, Contour current method, Topologically isomorphic transformations.

Findings. The mathematical apparatus created and implemented as a program in MATLAB allows solving the problems of modeling and research of electromagnetic devices in parts (by types of stored energy).This makes it possible to simplify the research and optimization of such technical characteristics as efficiency, mass-dimensional indicators, etc. The magnetic circuit is depicted in the same detail as the electric circuit, and is described by a contour matrix. The mathematical description of electromagnetic devices determines the inductive parameters due to the geometric dimensions and characteristics of the magnetic conductors. The topology of the electrical circuit is represented by matrix blocks, which allows obtaining a mathematical description that simultaneously takes into account the distribution of currents and charges in the elements of the circuit. The system of equations is reduced to the Cauchy form and is composed taking into account the increments of magnetic fluxes and potentials on capacitors, which simplifies its solution by numerical methods on a computer. Thus, it is convenient to control the energy processes in the reactive energy-consuming elements of the circuit. The paper presents an example of research of a charger of a pulse current generator with an inductive-capacitive converter. In the research example, the expected qualitative characteristics were obtained.

Originality. The mathematical model of electromagnetic circuits does not provide for equivalent transformations associated with the geometric configuration of magnetic conductors. The topology of the electromagnetic circuit is presented in the form of separate matrices, which are connected by a matrix of coil connections.

Practical value. The implemented software in the MATLAB shell uses the parameters of magnetic conductors in the form of geometric dimensions of magnetic conductors and their technical characteristics. The results of modeling a powerful electromagnetic devices allows you to estimate the accumulated energy of the electric charge in capacitors and the magnetic field in magnetic circuits and to analyze the efficiency and pos-sible impact on the environment. The presented data preparation technology allows us to investigate processes in more complex magnetic structures, for example, in magnetic flux-controlled transformers.

Features of the creation of electric power quality control systems in power supply systems of space rocket complexes

V.S. Reva — 2025-04-30

Purpose. Solution of electric power quality issues at space rocet complexes during the execution of launch preparation and launch cycles for the space rocket through the creation and solution of the electric power quality control system (EPQCS) as a separate structure within the power supply system of space rocet complexes PSS SRC with the provision of specified power parameters.

Methodology. Review of literary sources on the subject, method of expert evaluations, method of system analysis, method of experimental research.

Findings. Indicators of electricity quality, which are the most important for SRC electricity consumers, and which must be monitored, are given. The main requirements to EPQCS have been determined. In case of exceeding the permissible limits of electricity power quality indicators, EPQCS will allow to take operational measures necessary to counter off-nominal situations, by using to the management of the elements of the power supply system. Information security was carried out using a routinely adopted structural block diagram of such systems, on the basis of which the three-tier structure of the EPQCS was implemented. The algorithm and basic principles of the operation of the EPQCS in the nominal mode and the mode beyond the limits of the power quality indicators (PQI) are reviewed. A short description of the structure, as well as an example of the algorithm for managing the EPQCS subordinates, has been included.

Originality. The task of a comprehensive approach to electricity power quality indicators was solved and created electric power quality control system in the SRC power supply systems. Microprocessor control means primarily provide speed in comparison with similar systems based on analog-to-digital converters. The proposed EPQCS carries out electricity quality control with the display of data on the operator's screen in real time, continuous monitoring with fixation and registration of the main parameters, as well as notification of the operator in case off-nominal situations.

Practical value. Developed, manufactured and successfully passed all types of tests of the electric power quality control system for the SRC «Сyclone -4» (Brazil), and partly for the SRC «Сyclone -4М» (Canada).

Research on power distribution in a microgrid with distributed electricity sources

M.Y. Oliynichenko — 2025-04-30

Purpose. Assessment of power flow distribution in a microgrid with autonomous sources to identify the impact of power levels on frequency and voltage levels.

Methodology. The analysis of existing research in the field of electric power engineering has been conducted, focusing on the management of power flows in microgrids with autonomous small- and medium-capacity generating units. As a result of the analysis, it has been established that a relevant challenge is the control and management of active and reactive power flows in microgrids to maintain the frequency and effective voltage level at a predefined value. It has been noted that this issue presents certain complexities due to the instability of primary energy flows from alternative sources, which can lead to both energy shortages and surpluses. Based on the theoretical foundations of electrical engineering and utilizing methods and techniques commonly applied in power supply system calculations, a simulation model with alternative energy sources has been developed, taking into account the power supply system structure of a small agricultural enterprise..

Findings. In the Simulink/Matlab visual programming environment, a simulation model has been developed that enables the study of active and reactive power distribution at network nodes and the monitoring of frequency and voltage magnitude variations. During the research, several experiments were conducted with specific distributions of active and reactive power between consumers and generating units in the microgrid under both parallel and autonomous operating conditions. As a result of the experiment involving disconnection from the external grid and changes in load levels, greater voltage fluctuations and a redistribution of reactive power between consumers and generating units were observed. This phenomenon is primarily caused by the formation of active and reactive power in the dynamic load block, where calculations are linked to the baseline voltage and frequency levels..

Originality. As a result of summarizing the obtained time diagrams, it was found that the calculation of active and reactive power, both for loads and generating units, must be performed considering the current frequency and voltage level at the observation node relative to the baseline values

Practical value. The obtained results should be taken into account in the implementation of control systems for autonomous power sources, specifically in the methods for calculating the current controlled values of active and reactive power.

Study of the nature of emergency transient processes in power supply systems of enterprises

Yu.A. Papaika — 2025-04-30

Purpose. To investigate the nature of emergency transient processes in power supply systems of enterprises in order to identify the main causes of emergency situations, identify the features of the processes, and assess their impact on the reliability of power supply systems. The article aims to study the impact of neutral modes on human safety and to study methods for controlling the insulation of networks with a voltage of 6–10 kV to improve the safety of operation of electrical networks of enterprises.

Methodology. The study of the nature of emergency transient processes was carried out through statistical analysis of data processing on the occurrence of emergency situations at operating enterprises of Ukraine and analysis of existing calculation methods given in the scientific and technical literature. The main causes and patterns of process development were determined by analyzing emergency processes that occur in networks with an isolated neutral during a single-phase "metal" ground fault at the initial stages of the emergency mode and in the post-emergency mode.

Findings. The result of the analysis of the main patterns of the course of emergency transient processes in the power supply systems of enterprises is the determination of the initial nature of the processes in networks with an isolated neutral during a single-phase ground fault and the nature of the processes in the post-emergency operating mode. The article also derives formulas for calculating the neutral mode impact on human electrical safety during the operation of distribution networks. In order to increase the reliability of power supply systems and reduce the likelihood of emergency situations, the article proposes a method for controlling the insulation parameters of electrical networks with a voltage of 6 - 10 kV.

Originality. Determination of the modern equipment impact on the nature of emergency transients, including nonlinear load and higher harmonics. Evaluation of the relationship between the transient process parameters and the power supply reliability, the impact of emergency modes on the technological processes of the enterprise.

Practical value. The result of the study makes it possible to assess the consequences of emergency transients in the power supply systems of enterprises, which leads to an increase in the reliability of power supply systems and improvement of labor safety conditions at energy facilities. Study of the influence of the neutral mode on electrical safety during the operation of distribution networks.