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E-Journal N1-3(42)2019

"PROBLEMS of the REGIONAL ENERGETICS (special issue) in progress"

CONTENTS

0 INTERNATIONAL SCIENTIFIC-PRACTICAL CONFERENCE “ELECTROTECHNIC AND COMPUTER SYSTEMS: THEORY AND PRACTICE” ELTECS-2019
1 The Method of Determining the Turbogenerator Characteristics Using Automated Numerical Calculations of Magnetic Fields
Authors: Milykh V. I., Revuzhenko S. A. National Technical University «Kharkiv Polytechnic Institute» Kharkiv, Ukraine
  Abstract: A typical way for obtaining the characteristics of the electric machines are the methods based on the theory of the magnetic circuits. These methods contain assumptions that lead to significant errors in the calculation results. Modern software allows to perform calculations of the magnetic fields using the numerical methods, and, it is thus possible to obtain more adequate characteristics of the electric machines, which are indicative of their working properties in operation. Hence, the aim of this study is to describe the method of obtaining the characteristics of a high power turbogenerator by the calculation of its magnetic fields. The proposed methods for determining the characteristics of the electric machine under study are based on the iterative methods using the automated numerical calculations of the magnetic fields. The calculations were carried out using the FEMM software finite element method and the Lua script. The paper presents characteristics of turbogenerator such as the idle speed and short circuit, angular, stator winding excitation, adjusting and U-shaped. The adequacy of the calculations was checked by comparing the obtained characteristics with those calculated by classical methods. The most important results of the work are the obtained differences in determining the characteristics by numerical calculation and calculations using the theory of magnetic circuits. Their significance lies in the fact that the modernization of turbogenerators often takes an increase in their power by an amount commensurate with the error by using the classical method of obtaining characteristics based on the theory of magnetic circuits.
  Keywords: turbogenerator characteristics, electromagnetic values, magnetic field, iterative numerical calculations.
DOI: 10.5281/zenodo.3239170
2 Control of an Electrical Vector Drive of a Mechanical Variable Masses’ System
Authors: Kvashnin V. V., Babash A. V., Kosenko V. A., Kvashnin V. O., Klimenko G. P. Donbass State Engineering Academy Kramatorsk, Ukraine
  Abstract: The aim of this paper was the development of a positional system model for a vector control of a static loads’ stand using the electrical drive and the study of the effect of various types of speed controllers and their settings on the dynamics of the transient processes during the simulation of the regulation and disturbance actions. This goal was achieved by the development of a vector control system model using the stand electric drive with the PID-speed controller setting, which ensured minimal speed errors and restrictions in the dynamic loads during the regulating and disturbing action. The synthesis of the current control circuits of the stator and speed in the torque control channel was performed. It was shown that using the existing PI-regulators of speed and current and their settings, the speed dynamic error was found to be as high as 21% at a regulating action, whereas during the disturbing action it was 8%. The achievement of the above indicators of the regulation quality was possible in the presence of the intensity setter at the speed regulator input. In this case the dynamic speed error while operating under control increased substantially. The introduction of the speed PID controller made it possible to reduce dynamic errors, however, it gave no desired results with the standard configuration. Changing the controller’s proportional part parameters allowed us to minimize the dynamic speed error while operation, both under regulating or disturbing influences.
  Keywords: vector control, PI controller, PID controller, correction, quality indicators, mathematical model, functional scheme.
DOI: 10.5281/zenodo.3239202
3 Eco-design of Electric Equipment
Authors: Tsutsuianu O. Romanian National Committee of the World Energy Council Bucharest, Romania
  Abstract: In the last time, some factors and especially the environmental protection requirements have forced to add the ecological criterion for design of electric equipment, within a new Eco-design concept. The essence of this concept consists in the integration of environmental aspects at project phase, taking into account full life cycle of product. The work presents some theoretical and practical aspects of eco-design for electric equipment. The actual eco-design conception com-bines Qualitative Assessment of Life Cycle Criteria with a quantitative method based on the Product Carbon Footprint. The calculation of the last indicator means the quantification of the greenhouse gases emissions (kgCO2 equivalent) during the life cycle of products and services. From the study of the technical literature and its own practical work, the author has found that "maintenance", one of the phases of the life cycle of electric equipment, is not sufficiently analyzed and quantified in terms of negative impacts on the environment, including CO2 emissions involved in the service performed. As a result, it has achieved himself and in collaboration with other specialists studies and research, with the ultimate objective of establishing environmental performance indicators in this field. Thus, the main objective of this paper refers to the original contribution of the author who has established two such indicators, namely: 1. Absolute indicator "CO2 emissions involved in service (Es) [kg CO2]" and 2. Relative indicator "Specific CO2 emissions involved in service (es) (kg CO2 / euro)".
  Keywords: environmental legislation, eco-design, life cycle of product/service, product carbon footprint, environmental performance indicator, CO2 emissions.
DOI: 10.5281/zenodo.3239204
4 Power Balanced Adjustment of Quad-Inverter Installation with Modified Discontinuous PWM
Authors: Oleschuk V., Ermuratskii V. Institute of Power Engineering of Moldova Kishinau, Republic of Moldova
  Abstract: Abstract. Purpose of this work is in the development and modification of control scheme and of basic algorithms of discontinuous space-vector modulation for synchronous and balanced regu-lation of multi-inverter topology of six-phase open-end winding installation with four insulated dc sources. This purpose has been achieved due to including in the control and modulation scheme of specialized control correlations connecting coefficients of modulation of inverters, required power ratio between dc-links, and voltages of the corresponding dc sources. So, basic novelty of this research is in the fact, that the elaborated and investigated control and modula-tion algorithms for installation on the base of inverters with discontinuous space-vector modula-tion (with both 300-non-switching intervals and 600-non-switching intervals) insure both required power sharing capability between dc links and advanced harmonic composition (without even harmonics and subharmonics) of spectra of the phase and line voltages of six-phase installation. Mutual comparison of behavior of system with two basic schemes of modified discontinuous pulsewidth modulation (PWM) has been executed. Investigation of harmonic composition of the phase voltage of multi-inverter system illustrates an important fact, that for the all analyzed con-trol modes, connected with balanced adjustment of drive under different conditions, phase volt-age of installation has symmetry for any control regimes, including control modes with fraction-al frequency ratios between switching frequency of converters and fundamental frequency of installation, with absence in its spectra of undesirable subharmonics. Factor of minimization of subharmonics in spectra of voltage and current of ac drives of different topologies is especially important for the medium-voltage medium-power installations on the basis of PWM converters.
  Keywords: voltage source inverter, induction motor, modulation strategy, voltage spectra, integral harmonic composition.
DOI: 10.5281/zenodo.3239206
 
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