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In the paper special attention is given to application of pulsed-arc tandem welding by coated electrodes. Mock-ups of equipment for tandem welding and surfacing were developed and studied. A scheme was proposed for tandem arc welding by stick coated electrodes, fi tted with capacitive energy storage devices, as well as a device-attachment that allows using any welding current source to perform this kind of welding operations. The attachment operation is based on the principle of controlling the electrode melting rate that ensures their uniform mutual burnout. Also shown are time diagrams, which clarify the principle of operation of the device, photos of surfaced samples, oscillograms of currents supplied to the welding electrodes. 7 Ref., 8 Fig. [ABSTRACT FROM AUTHOR]

Harmonization of the requirements of certain groups of electrical and electrotechnological consumers of electricity with the current supply conditions requires in many cases the use of converters. Prominent among the systems designed to purposefully change the supply voltage of such consumers (regulation, stabilization) are converters with transformer- and-switches executive structure or tap changing (smart) transformers, which use discrete-time control, in particular so-called multi-level AC rectifiers (MLR). In the synthesis of MLR the main problem is to determine the optimal law of sectioning of the secondary envelope of its transformer. The paper analyzes the features of MLR decomposition into two functionally identical blocks under the given limitation of the output voltage control range and its difference from the decomposition of wide-range MLRs. The a priori variety of circuit technical solutions of such MLRs is determined. New MLRs with high efficiency of semiconductor switch elements use are offered. [ABSTRACT FROM AUTHOR]

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Purpose. Determining the rational structure of the automatic control system of the motorcompressor, which provides minimal energy losses when switching on and going to a steady state mode of operation of a household refrigerator. Methodology. The methods of simulation modeling, comparative analysis, research of control systems and the main provisions of technical thermodynamics and the theory of automatic control are used in the work. Findings. The paper considers the principle of operation of the refrigeration unit of a household refrigerator, schematically shows its main elements and the relationship with the steam compression cycle. Simulation models of automatic control systems based on proportional-integral-differential controller, fuzzy and hybrid controllers have been developed. The proposed models allow to evaluate the quality of temperature control in the refrigeration compartment and to determine energy losses during transients. The results of computer simulation of transients in temperature control systems due to changes in the performance of the motor-compressor and the obtained values of power losses are presented. It is established that the smallest losses of the electric power at instant increase of heat inflows in refrigerating department occur at application of a fuzzy regulator. It is determined that the use of fuzzy controllers in automatic control systems reduces the duration of transients, the time of the first negotiation, the number of oscillations, but leads to static error and increases the maximum deviation from the set temperature in the refrigerator compartment. Originality. Simulation models of control systems of the motor-compressor of a household refrigerator for assessment of quality of regulation and definition of losses of the electric power during transient processes are developed. Practical value. The ways to increase the energy efficiency of household refrigerators through the introduction of control systems with fuzzy regulators are proposed. [ABSTRACT FROM AUTHOR]

In the paper the problem of the transients forecasting for electric power systems and their objects based on real time characteristics obtained during their registration using modern monitoring systems of regime parameters and state of electric power systems. It is proposed to create macromodels of power system components in the form of state variables and "black box" approach using the data obtained during field experiments or registered normal and fault regimes for fast prognosis of the transient processes flowing. The development process of the substation Albertirsa macromodel based on "black box" approach and fault regimes data registered by Regina monitoring system is described and obtained results are presented. [ABSTRACT FROM AUTHOR]

The paper considers the frequency load shedding of an electric power system. The objective of this paper is to enhance the structure and algorithms of frequency load shedding-1 (AUFLS-1) using cutting-edge technologies, namely Wide Area Measurement System. We model the operation of the system of complex power supply when various emergencies in the Power Factory software occur. We aim at revealing the fact of the voltage corner reaction on the emergency occurrence and elaborating the algorithm of detecting the emergency by speed of voltage corner change. The result and novelty of this research is that we propose how to upgrade the system AUFLS-1 by introducing the additional starting block reacting to the speed of the voltage corner change which increases the speed of AUFLS-1 system operation. As a result the system AUFLS-1 starts up not only by achieving "frequency" set point but also by analyzing the speed of voltage corner change. [ABSTRACT FROM AUTHOR]

Global decarbonisation and widespread use of alternative and renewable energy sources aims to shortage the fossil fuel using and reduce the harmful impact on the environment within the framework of the sustainable development paradigm. At the same time, wide integration into the power network of unmanaged generating units based on renewable energy sources in the absence of a sufficient number of electric energy storage units of the required capacity in conditions of unpredictability and instability of production may lead to the inability to provide reliable coverage of the consumers power load, which requires the use of alternative ways of balancing the power system. Under such conditions, the coordination of electric power (electricity) demand and supply for should be carried out exclusively by demand-side management in real time or near real time. That is why the improvement of methodological and instrumental provision of demand-side management tasks today is one of the most important components of the effectiveness of the "green" transition. To achieve the goal, the article analyzed the existing DSM-methods, performed an analysis of the requirements of national regulatory documents for DSM and service provision in the liberalized electricity market of Ukraine, described an improved ideal norm method and a modernized toolkit for demand-side management, as well as a reliable budgetary technical solution for the formation of information support for DSM in the retail electricity market is proposed, which together with dynamic pricing and the introduction of real-time tariffs will contribute to ensuring economic regimes of operation of the IPS and high-quality power supply to consumers. References 14, figures 4, tables 2. [ABSTRACT FROM AUTHOR]

The paper considers the European approaches to assessment of the buildings' energy efficiency. We scrutinize their advantages and disadvantages. Specifically, we investigate the feasibility of one of the approaches by employing the example of NTUU "KPI" educational buildings and define principal obstacles that hinder the utilization and can also lead to misinterpretation of the results obtained. We propose possible ways of specification of existing methods and attempt to adapt them to the Ukrainian context. [ABSTRACT FROM AUTHOR]

In this paper, we study the influence of chrome, manganese and nickel on hardness and wearproof of white cast-irons, assigned for making the poured detail parts of dredging pumps of the systems of ash hydro-disposa thermal electric power station. We optimize the microalloying technology using titan, vanadium, antimony and modification of chrome-manganese cast-iron by boron to improve its special properties. [ABSTRACT FROM AUTHOR]

The methods of determination of electric energy consumption norms that can be used for forecasting the own needs of DC traction substations are offered in the paper.

Copyright of Scientific Journal of National University of Life & Environmental Sciences of Ukraine. Series: Technique & Energy of APK is the property of National University of Life & Environmental Sciences of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose. To substantiate the possibility of 35 kV voltage application in deep-level ore and coal mine power supply systems to supply underground electric collectors and draw up the principles of ensuring their operational safety. Methodology. We have used theoretical and experimental methods, in particular, probability theory and analytical research methods to estimate electrical elements reliability and power supply electric safety; general electrical circuit theory to estimate emergency processes. Findings. By selection of appropriate level of voltage we can solve the deep mines power supply problem comprehensively and for extended period of time taking into account growing electrical loads in underground electric collectors. This way of improving the efficiency of deep-level energy-intensive mines supply appears the most realistic and technically feasible. To reconstruct the power supply system we can supply 35 kV voltage to the depth over 1000 m to the 35/6 kV underground substation and distribute power at deeper horizons with voltage of 6 kV. Between different schemes of power supply for the 35/6 kV underground substation the most preferable is the scheme 'block line - transformer' allowing to refuse the 35/6 kV distribution device and meet existing general and specialized requirements of maintenance and safety. We have presented theoretical substantiation of the selective method of automatic and continuous monitoring of 35/6 kV electrical grid isolation parameters. This method is based on impinging of operational bi-frequency sinusoid signals of nonindustrial frequency on electrical grid, and on the principle of faulted phase earth protection during ground faults in 6-35 kV electric grids for the purposes of improving the electrical safety. Originality. Alternative method of improvement of the power supply effectiveness in deep geological position is presented. We have shown that change-over to a higher voltage class of mine supply networks is a promising method. To ensure the safety, we propose the method of automatic, continuous and selective monitoring of isolation parameters relative to ground without removing the operating voltage. Practical value. Improvement of the effectiveness of power supply in deep geological position can be performed through power quality enhancement and reducing the energy loss. [ABSTRACT FROM AUTHOR]