INCREASING THE ENERGY EFFICIENCY OF THE AC ELECTRIC LOKOMOTIVE TRACTION DRIVE

The study of the energy characteristics of the active traction converter with pulse-width modulation as part of the traction electric drive of an AC electric locomotive was held during the research. Active traction converter provides pulse-width control of the collector DC traction motors voltage and belongs to the basic AC / DC circuit. The transient process when switching transistor switches is accompanied by significant voltage surge, due to the scattering inductance reaction of the traction transformer. Studies have shown that the diode discharge buffer circuits do not provide discharge of the electromagnetic energy accumulated in the winding of the transformer. An active traction converter control algorithm has been developed, which implies the use of pulse-width and phase regulation of rectified voltage. Switching of transistor switches occurs in the presence of a parallel current circuit. This creates the conditions for the discharge of electromagnetic energy accumulated in the secondary winding circuit of the traction transformer. The developed mathematical model allows to investigate the electromagnetic processes that occur during the switching of transistor switches and to evaluate the energy efficiency of the electric locomotive with active traction converter. In the simulation process, the influence of active traction converter parameters and control algorithms on the power rate of the converter, the total THD distortion rate of current and voltage and the relative values of the rectified voltage were investigated. Measures to increase the power rate and to reduce the emission level of higher current harmonics into the traction network were proposed.

Mutual influence of currents in plane inductor system with solenoid between two massive conductors

Introduction. Inductor systems, as tools for metal processing, widely used in industrial technologies using the energy of powerful pulsed electromagnetic fields. Problem. A common disadvantage of the known works on the creation of tools for magnetic-pulse impact on conductive objects has the use of physical and mathematical models, in which the exciting currents do not depend on the ongoing electromagnetic processes. Such the assumption, have distorts the picture of the real energy in the working area of the inductor system. Goal. To obtain design ratios and numerical estimates of the mutual influence of exciting and induced currents of a flat inductor system with a circular solenoid located between massive well-conducting objects, moreover to carry out a theoretical analysis of electromagnetic processes in this system. Methodology. Have applied integrating Maxwell’s equations using the Laplace and Fourier-Bessel integral transformations in the approximation of the ideal conductivity of the metal objects to be processed. Results. The calculated relations for the theoretical analysis of electromagnetic processes have obtained in the high-frequency approximation. It shown that the inductance of the studied system decreases as the objects being processed approach the solenoid and increases as they move away from it. It found that for the invariability of the power indicators, of the proposed tool, a corresponding correction of the amplitude (on average up to 20 times) of the exciting current has necessary in the solenoid winding. Originality. For the first time, the tool design with a circular solenoid located between the massive metal objects has proposed for flat magnetic-pulse stamping. As a result of the theoretical analysis, the influence of electromagnetic processes on the currents flowing in the system has confirmed. Practical significance. The use of the results obtained will allow to increase the efficiency of the tool of magnetic-pulse technologies, and to reduce the energy costs for performing the specified production operations.

Methods and equipment for power supply of underwater vehicles

Object and purpose of research. The object of the work is the power supply systems of submersibles. The aim is to assess the characteristics of the submersible energy supply systems and find ways to improve them. Materials and methods. The study was conducted on the basis of analytical methods and computer simulation of electromagnetic processes of the systems of energy supply of submersibles. Main results. A comparative assessment of the characteristics of the main systems of energy supply of submersibles has been carried out. New ways and devices powering submersibles, developed methods for calculating these devices. Ways to improve the power supply systems of submersibles are shown. Conclusion. The results of the research allow us to identify ways to further improve the characteristics of the power supply systems of submersibles and to speed up the process of their implementation in practice.

DEVELOPMENT OF POSSIBILITIES OF THE METHOD OF INDIVIDUAL COMPONENTS FOR ANALYSIS OF MODES IN ELECTRICAL SMART- COMPLEXES

The peculiarities of the formation of the local power system according to the concept of Smart Grid requires a qualitatively new architecture of the power supply system and new principles of operation - both at the level of technical solutions and mechanisms of organizational interaction at the technological level and financial calculations. The scientific and technical problems connected with functioning of separate types of electrotechnical Smart-complexes (ETK-Smart) are analyzed, features of the analysis of electrotechnical complexes with nonlinear elements by the analysis of processes in case of changes of active and reactive loadings that allows to consider corresponding changes of parameters at calculations of electromagnetic processes using analytical methods. The methodology for assessing the impact of conductive periodic interference on the flow of the steady state in electrical Smart-complexes has been improved. The principles of analysis (modeling) of ETC- Smart as systems with periodically changing parameters are considered. It is shown that the use of ETC-Smart requires meticulous attention to the analysis of steady-state and transient, including modulated, modes, in the case of formation of different schedules of energy and technological processes, power supply of various types of loads, etc. Algorithms for calculating currents in electrical complexes with cyclically variable parameters, as well as analysis of the influence of periodic conductive interference in ETC-Smart elements with power converters based on the development of the capabilities of the method of individual components in modeling steady-state modules. Thus, algorithms for analysis of electromagnetic processes in ETC-Smart with variable parameters and RL-load for complex periodic, system analysis in case of nonlinear elements, analysis of internal resistance of generator and transmission lines, analysis of processes in abrupt change of parameters of reactive elements (inductance L) and capacitance C), analysis of the influence of periodic conductive interference (AC and DC) on electromagnetic processes in the elements of ETC-Smart with power converters The basics of methodological support for assessing the energy efficiency of ETC-Smart as elements of intelligent power supply systems are presented. The algorithm of electrotechnical inspection (energy audit) of electrotechnical complexes by application of the offered analytical expressions and the generalized algorithm of calculation of electromagnetic processes in electric complexes with cyclically variable parameters is offered that allows to carry out the corresponding estimations of energy efficiency of functioning. The concept of formation (construction) and modernization of optimization of elements of Smart-technologies for the Smart-microdistrict of the intellectual city by development of algorithm of realization of the corresponding researches and estimations and formation of the Microgrid network (ETC-Smart with power converters) of several levels of hierarchy is offered. and assessment of the general energy efficiency indicators of the Smart-microdistrict of the intellectual city. The presented examples of analysis confirm the effectiveness of the modification of the method of individual components for the analysis of steady-state ETC-Smart.

Computer simulation of a power source based on a bipolar pulse shaper for magnetron sputtering systems

The research object is a pulsed bipolar power supply based on a bipolar pulse shaper of increased frequency for magnetron sputtering systems. The research subject is the electrophysical and electromagnetic processes occurring in the bipolar pulse shaper when it is operated with a magnetron sputtering system, as well as the control characteristics. The purpose of the paper is the possibility of creating a pulsed power supply with a power of up to several tens of kW, which makes it possible to increase the stability of the magnetron sputtering system. Besides, the outcomes of computer simulation of a power source based on a bipolar pulse shaper and control algorithm ensuring its stable and reliable operation in association with a magnetron sputtering system are reflected in the paper. The results show that the deviation of the output control characteristics of the bipolar pulse shaper from the analytically obtained characteristics does not exceed 3%. Circuit modeling is carried out in the Swicher CAD/LTspice software package. The mathematical SPICE models of the field-effect STY112N65M5 transistor, transistor IGBT of IRF4PF50WD and STTH8006 diode are taken from the websites of STMicroelectronics and International Rectifier manufacturers.

Electromagnetic processes in an anisotropically electrically conducting liquid in a running magnetic field

Objective: Purpose is the study electromagnetic processes in an electrically conducting liquid (with anisotropic conductivity) flowing in the channel of an MHD-alternator under the acting of a running magnetic field. Methods: We used Maxwell's equations to describe the electromagnetic processes. Galerkin method is used to determine the current functions. Results: For the case of small values of the magnetic Reynolds number the equations for the induced field and currents in an electrical conducting liquid are given in the form of converging power series. It is shown that for a sufficiently accurate determination of the current functions it is necessary to take into account the first three terms of the series. The first two terms of the other series must be taken into account to determi-nate the solution for the induced field. It is revealed that the induced currents in an electrically conducting liquid consist of currents of zero, main and double frequencies. The currents of zero and double frequencies play a negative role since they lead to an increase in joule losses and the for-mation of forces. These forces do not make the useful work. To reduce them the side walls of the channel should be conductive. We established that the anisotropy of the electrical conductivity of the liquid causes a decrease the currents of the main frequency. Practical importance: The magnet-ic Reynolds number significantly affects the field distribution in a liquid metal. The field of the main frequency increases with its increase and the fields of zero and double frequency become smaller. At the small values of Reynolds number the Hall effect is stronger and the field distribution is less symmetrical. At large values the field distribution is symmetrized due to a decrease in the zero and doub¬le frequency fields.

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.

MATHEMATICAL MODELING AND ANALYSIS OF ELECTROMAGNETIC PROCESSES IN THE THYRISTOR CURRENT REGULATOR SYSTEM - SPECIAL TRANSFORMER INSTALLATION INSTALLATION IN BCF

Peculiarities of mathematical modeling are considered and electromagnetic processes in the system “thyristor current regulator - special transformer” (TRS-ST) are analyzed. An indirect method for measuring the temperature of a die plate, which is controlled by the primary current of the CT, is proposed. A simulation model of the TRS-ST system has been created, which makes it possible to take into account the nonlinearity of the characteristics of the transformer core material and the nonlinearity of the load resistance to achieve the required accuracy of electromagnetic processes. The results of simulation confirmed the effectiveness of the developed mathematical model as the difference between the curves of transients obtained by modeling and the curves obtained during research on the experimental setup is not more than 5% and allows to further optimize multi-loop control systems with interconnected and nonlinear parameters. Bibl. 9, fig. 13.