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  Problemele energeticii regionale

E-Journal №1(27) 2015



1 Investigation of Asymetric Modes of Three-phase Three - legs Phase-shifting Transformer with “Inverse Double Zigzag” Scheme of Windings Connections and Commutation in Neutral Point
Authors: Bosneaga V.A., Suslov V.M. Power Engineering Institute of Academy of Sciences Chisinau, Republic of Moldova
  Abstract: The model for power three-phase three limbs phase-shifting transformer with “inverse double zig-zag connection” was investigated. Calculations and research of steady state asymmetric modes of transformer with such windings connection were fulfilled, taking into account the electromagnetic coupling of the windings, located on different legs. The analysis was made for the most specific steady state asymmetric modes, that occur during different short circuits and asymmetric no load regimes, associated with the appearance of zero sequence magnetic flux. Vector diagrams for windings currents and voltages were constructed, as well as for the relative values of magnetic fluxes in legs, which in ensemble give a clear idea about their particularities.
  Keywords: model of power three legs transformer, asymmetric modes, zero-sequence magnetic flux.
2 Three-Phase Phase-Shifting Transformer with Regulation in Neutral Point
Authors: Kalinin L., Zaitsev D., Tirshu M., Golub I., Moraru L. Institute of Power Engineering of the Academy of Sciences of Moldova Chisinau, Republic of Moldova
  Abstract: The paper aimed to research mode characteristics of phase shift installation based on one three-phase transformer having three windings. Usually, such installations are two cores: exciting transformer and regulation transformer. In paper the installation functional scheme description, as well main relations which determine currents and voltages character in scheme elements during regulation process are given. It is shown, that installation is able to provide phase shift angle regulation up to . The installation scheme is designed to place the control module in the neutral connection point of regulation windings. Such solution allowing essential reduction of installation rated capacity compare to traditional one and excluding necessity of special isolation of shell. Proposed solution ensure in such mode compact construction and commodity for transportation, mounting and service.
  Keywords: phase-shifting transformer rated capacity, complex transformer factor, phase-shift angle.
3 Modes of Interphase Power Controller Operation
Authors: Kalinin L.P., Zaitsev D.A., Tirsu M.S., Golub I.V. Institute of Power Engineering of the Academy of Sciences of Moldova Chisinau, Republic of Moldova
  Abstract: The IPC (Interphase Power Controller) technology is a developing direction in the domain of power systems interconnections. The practical application of these devices will improve the efficiency of power systems operation and prevent the spread of undesirable phenomena in electric networks. This may result in new regimes effects that require special consideration and analysis. The paper discusses some features of IPC operation at the installation of it on the input end of transmission line. The purpose was to study the characteristics of the transmission line, when on the transmitting end was mounted uncontrolled IPC with centered characteristics. Additional ways of using the phase shifting transformers (PST) to adjust the power characteristics of IPC are considered as well. In this case the PST acts as a reactive power compensator. Favorable conditions IPC operation can be obtained by applying an additional phase-shifting element mounted IPC for power at the receiving end. It is concluded that the installation phase-shifting device (beginning or end of the line) does not matter and it can be determined based on specific conditions. Results testify the possibility of full harmonization of IPC with the line in all practical cases.
  Keywords: interphase power controller, power transmission, phase shifting transformer, susceptances.
4 Multilevel Converters with Voltage Waveform Symmetries for Power Six-Phase Traction Drive
Authors: Oleschuk V., Ermuratskii V. Institute of Power Engineering of the Academy of Sciences of Moldova Chisinau, Republic of Moldova
  Abstract: Research of dual three-phase transport-oriented power conversion system on the base of four three-level inverters with specialized switching strategy insuring both synchronization of control modes of inverters and quarter-wave symmetry of the phase voltages of system has been executed. Detailed modeling of processes in systems with basic versions of control algorithms has been done. It has been shown, that value of weighted total harmonic distortion factor of the phase voltage of controlled ac electric drive system with four three-level inverter is up to 60-95% lower than for a similar system based on two inverters. The use of algorithms of discontinuous synchronous modulation assure lower (up to 15%) value weighted total harmonic distortion factor of the phase voltage in comparison with the corresponding integral spectral characteristics of the phase voltage of system, controlled by algorithms of direct synchronous modulations.
  Keywords: voltage source inverter, algorithms of pulsewidth modulation, dual three-phase system, modulated output voltage, harmonics, spectral composition.
5 Active Power Flow Optimization of Industrial Power Supply with Regard to the Transmission Line Conductor Heating
Authors: Leyzgold D.Yu., Chudinov A.V. Perm National Research Polytechnic University Perm, Russian Federation
  Abstract: This article studies the problem of the transmission line conductor heating effect on the active power flows optimization in the local segment of industrial power supply. The purpose is to determine the optimal generation rating of the distributed power sources, in which the power flow values will correspond to the minimum active power losses in the power supply. The timeliness is the need to define the most appropriate rated power values of distributed sources which will be connected to current industrial power supply. Basing on the model of active power flow optimization, authors formulate the description of the nonlinear transportation problem considering the active power losses depending on the transmission line conductor heating. Authors proposed a new approach to the heating model parameters definition based on allowable current loads and nominal parameters of conductors as part of the optimization problem. Analysis of study results showed that, despite the relatively small active power losses reduction to the tune 0,45% due to accounting of the conductors heating effect for the present configuration of power supply, there are significant fluctuations in the required generation rating in nodes of the network to 9,32% within seasonal changes in the outer air temperature. This fact should be taken into account when selecting the optimum power of distributed generation systems, as exemplified by an arbitrary network configuration.
  Keywords: active power flow distribution, optimization of load in power supply, heating conductors.
7 Thermal Efficiency of Power Module “Boiler with Solar Collectors as Additional Heat Source” For Combined Heat Supply System
Authors: Denysova A.E., Mazurenko A.S., Denysova A.S. Odessa National Polytechnic University Odessa, Ukraine
  Abstract: The purpose of work is to increase the efficiency of the combined heat supply system with solar collectors as additional thermal generators. In order to optimize the parameters of combined heat supply system the mathematical modeling of thermal processes in multi module solar collectors as additional thermal generators for preheating of the water for boiler have been done. The method of calculation of multi-module solar collectors working with forced circulation for various configurations of hydraulic connection of solar collector modules as the new result of our work have been proposed. The results of numerical simulation of thermal efficiency of solar heat source for boiler of combined heat supply system with the account of design features of the circuit; regime parameters of thermal generators that allow establishing rational conditions of its functioning have been worked out. The conditions of functioning that provide required temperature of heat carrier incoming to boiler and value of flow rate at which the slippage of heat carrier is not possible for different hydraulic circuits of solar modules have been established.
  Keywords: combined heat supply system, forced circulation, operation modes, multi-module solar collectors, boiler, thermal efficiency.
8 Combined Energy Supply System for Meat Processing Plants
Authors: Sit M., Sit B. Institute of Power Engineering of the Academy of Sciences of Moldova Kishinau, Republic of Moldova
  Abstract: The purpose of this study is the development of technological schemes of energy production for this industry in terms of energy efficiency. Technical solution that can reduce cost of the final production of meat production plant has been presented. The main idea of the tehnical solution is the use of turboexpander, which must be installed on gas reduction station near meat processing plant in the packet with the „air-water” gas – driven heat pump, which gas cooler serves as gas heating unit for the first stage of turboexpander. The thermal exit of gas engine serves as gas heating unit for the second stage of turboexpander and as heat energy generator for the plant and source of the heat for one of the evaporators of heat pump, as well. The second evaporator of heat pump is connected with the cold consuming equipment of the plant. The electric energy, which is produced by gas engine is consumed by heat pump compressor and electric equipment of the plant. Electric energy, which is produced by turbo expander is transmitted to the electric grid. The proposed technical solution can be used to reduce natural gas consumption on meat processing plants and the cost of production of electricity, heat and cold.
  Keywords: gas engine driven heat pump, turbo expander, meat processing plant, energy efficiency, carbon dioxide, refrigerant.
9 Indicators System Creation For The Energy Efficiency Benchmarking Of Municipal Power System Facilities
Authors: Davydenko L.V. Lutsk National Technical University Lutsk, Ukraine
  Abstract: The issues of the dataware of the comparative analysis procedure (benchmarking) for municipal power system facilities energy efficiency level estimation with a view of the hierarchical structure of the heat supply system are considered. The aim of the paper is the system of indicators formation for characterizing the efficiency of energy usage as on objects on lowest so on highest levels of power systems, proceeding from features of their functioning. Benchmarking methodology allows carrying out the estimation of energy efficiency level on the base of a plurality of parameters without their generalization in one indicator, but requires ensuring their comparability. Using the methodology of available statistical information that did not require deep specification and additional inspection structuring objectives and tasks of energy efficiency estimation problem has been proposed for ensuring the opportunity of benchmarking procedure implementation. This makes it possible to form the subset of indicators that ensure enough specification of the object of study, taking into account the degree of abstraction for every hierarchical level or sub problem. For a comparative analysis of energy using efficiency in municipal power systems at the highest levels of the hierarchy a plurality of indicators of the energy efficiency has been formed. Indicators have been determined with consideration of the structural elements of heat supply systems, but allowing taking into account the efficiency of the initial state of the objects, their functioning, and the questions of energy resources accounting organization. Usage of the proposed indicators provides implementation of energy using efficiency monitoring in the municipal power system and allows getting complete overview of the problem.
  Keywords: benchmarking, municipal power system, energy efficiency, energy efficiency indicators.
10 Stand for Experimental Evaluation of Effects of Hydrogen Use in Internal Combustion Engines
Authors: Levente B., Lelea D., Birsan N. University Politechnica Timisoara Timisoara, Romania
  Abstract: Hydroxy gas or the Brown gas or simply HHO, as it is called more often now days, is a highly flammable gas that has been around since the beginning of the XX-th century, when scientist Yull Brown has dedicated his work to study the properties and means of production of HHO by water electrolysis. In the second half of the century, the oil crisis, the simplicity of HHO production and its high combustion temperature and flame propagation have spurred the interest of ”garage inventors” around the world, who started doing practical experiments with HHO injection on personal vehicles and power-generators, in trying to reduce gas mileage, increase the engine performance and lower tailpipe emissions. Today, this technology is being rediscovered, again due to higher fuel prices and this time also due to some increasing concerns over global warming. Many have learned that HHO injection into the IC engine improves the gas mileage and reduces emissions, some reporting fuel savings of up to 40%, while others even claim to have reached the performance of operating their engines on HHO entirely produced onboard of the running vehicle. There are also reports that claim increased life span of the engine and engine lubrication, due to reduction effect of HHO on the solid hydrocarbon depositions onto the engine critical components, like pistons, valves, cylinder walls, etc. In this regard, the University Politehnica Timisoara Department of Mechanical Machines, Equipment and Transportation and Department for Applied Chemistry and Engineering of Inorganic Compounds and Environment, have joined together in a project to study and understand the mechanism that take place during HHO injection to IC engines, quantify the benefits and develop safer, better and more reliable materials for HHO on-demand and on-board production by water electrolysis.
  Keywords: hydroxy gas, internal combustion motor.
12 Principles Of Directed Energy Action In Food Nanotechnologies
Authors: Burdo O.G., Terziev S.G., Bandura V.N. Odessa National Academy of Food Technologies Odessa, Ukraine
  Abstract: The prospects of technologies of directed energy action (DEA) are discussed. Classification of DEA-technologies is offered. The purpose of the work is to give analysis of possibilities of DEA in food nanotechnologies. Combined processes of mass transfer during the extraction and drying are con-sidered by methods of mathematical modeling. The physical model of combined processes in DEA-technologies is analyzed. The classification of hydrodynamic flow from the capillary structures of food raw materials is given. Conditions of upgrowth of laminar and turbulent barodiffusion are set. Problems of experimental modeling are grounded. A new number of similarities, the number of ener-getic action, is discussed. That number correctly takes into account the specific of combined processes of DEA-technologies. It has been shown that impulse electromagnetic field is effective tool for realization DEA-technologies. Degree of intensification processes of mass transfer with application of barodiffusion and DEA-technologies can be by the order greater than possibilities of traditional technologies.
  Keywords: nanotechnology, barodiffuzion, energy, food technologies, modeling
14 Multifunctional Solar Systems Based On Two-Stage Regeneration Absorbent Solution
Authors: Doroshenko A.V., Antonova A.R., Garh Saed Educational and Research Institute of Refrigeration, Сriotehnology and Eco-Energetics Odessa National Academy of Food Technologies, Ukraine
  Abstract: The concepts of multifunctional dehumidification solar systems, heat supply, cooling, and air conditioning based on the open absorption cycle with direct absorbent regeneration developed. The solar systems based on preliminary drainage of current of air and subsequent evaporated cooling. The solar system using evaporative coolers both types (direct and indirect). The principle of two-stage regeneration of absorbent used in the solar systems, it used as the basis of liquid and gas-liquid solar collectors. The main principle solutions are designed for the new generation of gas-liquid solar collectors. Analysis of the heat losses in the gas-liquid solar collectors, due to the mechanism of convection and radiation is made. Optimal cost of gas and liquid, as well as the basic dimensions and configuration of the working channel of the solar collector identified. Heat and mass transfer devices, belonging to the evaporative cooling system based on the interaction between the film and the gas stream and the liquid therein. Multichannel structure of the polymeric materials used to create the tip. Evaporative coolers of water and air both types (direct and indirect) are used in the cooling of the solar systems. Preliminary analysis of the possibilities of multifunctional solar absorption systems made reference to problems of cooling media and air conditioning on the basis of experimental data the authors. Designed solar systems feature low power consumption and environmental friendliness.
  Keywords: Multifunctional systems, solar energy, solar collectors, regeneration, evaporative cooling, polymeric materials.
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