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ELECTROENERGETICS
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CHARACTERISTIC OF STEADY-STATE REGIME FOR ONE OF SCENARIOUS OF MOLDOVA RIGHT BANK POWER SYSTEM INTEGRATION TO ENTSO-E
Authors: Zaitsev D., Golub I, Kalinin L, Tirshu M.Institute of Power Engineering of Academy of Sciences of Moldova
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Abstract: The article deals with the integration scenario of Moldavian power system to ENTSO-E. Various options of the development of power generation on the territory of the Republic of Moldova have been proposed and analyzed in order to correspond with Energy Strategy of the Republic of Moldova until 2030. Analysis of steady-state operation has been performed regarding active power losses for entire power system, and also for the each element with differentiation on voltage levels. The computation and estimation of static stability factor for active power and for voltage were performed. Import/export of energy was estimated, and other indices of regime of energy system were analyzed as well. Technically effective variants were selected as a result of comparative analysis. |
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Keywords: power system of the Republic of Moldova, ENTSO-E, interconnection, power system, normal regime, active power losses.
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ZONAL SCHEME OF ELECTRIC SUPPLY NETWORK FOR INSTITUTIONS OF THE ACADEMY OF SCIENCES OF MOLDOVA
Authors: Gritsay M.A.Institute of Power Engineering of the Academy of Sciences of Moldova
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Abstract: Analysis of regime of operation of existing electricity network of academic institutions in the district of Television Center of Chisinau was performed. Calculations were performed on the base of actual power consumption. Losses of electricity in all parts of the network have been estimated as well. It has been demonstrated that due to the low power consumption, transformers of the system have been loaded less than 20%. As a result, losses in the steel (idling losses) of transformers dominate over value of losses of all networks (about 95%). Basic cause of increased losses was aging of the equipment. The losses in iron of transformers could be much greater than the certified value of the losses in transformers with a long life (20-30 years). Three efficient network configurations have been proposed. Power losses have been calculated for each topology of network. Advantages of the zonal scheme, as one of the most efficient power supply network, have been demonstrated. |
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Keywords: Electric network, operating mode, electric energy losses.
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DEFINITION OF NORMALIZED ENERGY EFFICIENCY INDICES OF RESISTIVE TWO-PORT NETWORKS
Authors: Penin A. A. (Ghitu Institute of the Electronic Engineering and Nanotechnologies)
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Abstract: The aim of the work was analysis of efficiency indices of power converters on the basis of various expressions of input and output power and power losses. A large number of per se formally introduced indices were marked. The most reasonable approach to an efficiency evaluation in relation to a reference regime was considered. It was method of comparison with standard. Such approach used a certain mathematical model. Also, necessity of justification of offered efficiency criteria expressions has been shown. Method of comparison with standard has been demonstrated and validated on example of resistive two-port network with changeable attenuation. Geometrical interpretation of power characteristic family led to introduction of the "idealized" two-port network besides the standard one. |
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Keywords: Efficiency index, two-port network, power characteristics, projective geometry.
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MODELING OF THREE-PHASE THREE LEG TRANSFORMER DEVICES FOR ENGINEERING CALCULATIONS OF ASYMMETRICAL MODES FOR DIFFERENT SCHEMES OF WINDING CONNECTIONS
Authors: V.A.Bosneaga, V.M. SuslovPower Engineering Institute of Academy of Sciences of Moldova
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Abstract: The model is proposed for the calculation and research of steady state asymmetric modes and transients in three-phase three legs transformer devices with arbitrary diagram of windings connection, taking into account the electromagnetic coupling of the windings, located on different legs. Using as an example distribution transformer of 10/0.4 kV calculations and analysis were performed of the most characteristic steady asymmetrical modes, that occur during short circuit, phase failure, unbalanced load for the most common windings connections and, in particular, associated with the occurrence of zero sequence magnetic flow. For the considered regimes and schemes vector diagrams were constructed for currents and voltages as well as for the relative values of magnetic flow, which give a clear idea about their particular features. |
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Keywords: model, asymmetric modes, three legs magnetic circuit, arbitrary windings connections, zero-sequence magnetic flow.
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MAXIMUM STEADY VOLTAGE AND CURRENT IN A HOMOGENEOUS ALTERNATING CURRENT LINE
Authors: Patsiuk V.I., Berzan V.P., Anisimov V.K., Kabak S.S., Postoronka S.A.Institute of Power Engineering of the ASM
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Abstract: The paper considers the problem of determining of maximum values of voltage and current in a long line. The processes have been analyzed at stationary processes, depending on the length of the line and its load. Line length has been varied from zero to its wave length. Range of the load value has been changed from short-circuit mode to idle mode. The method of complex amplitudes has been used for this research. Modes have been considered for the ideal line without distortion. Exact analytical solutions have been obtained for these types of circuits. Calculations have been made for lines with arbitrary losses. It has been found that for the ideal line and undistorted lines the set of the maximum voltage and current could be always achieved for degenerated modes. It has been observed that for the case of lines with arbitrary losses local maxima for current and voltage could take place (when the load on the mode of short- circuit current up to idle mode, and the physical length of the line from zero to its wave length). Introduction of dimensionless parameter of load, for short-circuit and no-load, made it possible to obtain generalized dependencies between changing of investigated parameters for any wave length of the line and the range of variation of its load. |
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Keywords: Ideal transmission line, arbitrary losses, method of complex amplitudes.
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HEAT AND POWER ENGINEERING
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ENERGY SUPPLY OF COMMERCIAL GREENHOUSE WITH THE GAS DRIVEN HEAT PUMP
Authors: Sit M.L., Ioisher A.M., Sit B.M., part IInstitute of Power Engineering of the Academy of Sciences of MoldovaDoroshenko A.V.,Cheban D.N.Educational and Research Institute of Refrigeration, Сriotehnology and Eco-EnergeticsOdessa National Academy of Food Technologies
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Abstract: The aim of the work is to develop energy efficient schemes of industrial greenhouse designed for year-round production of plants that requires year-round maintenance of strongly prescribed temperature and humidity inside the greenhouse. The complex "gas driven “water-air” heat pump – electric generator" (for use during the heating season) as well as the "gas driven heat pump “water-air” – electric generator – desiccant - evaporative chiller" which work in the off-season. The developed system produces heat and electricity (during the heating season) as well as cold and electricity (the rest of the year). Comparative analyses of greenhouse cooling by water and air cooling systems have been performed. Proposed structures have a high efficiency as compared with conventional circuits (boiler - chiller). |
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Keywords: Commercial greenhouse, gas driven heat pump, cogeneration, evaporative cooling, porous ceramics, combined refrigeration system.
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PERSPECTIVES OF USING OF EVAPORATIVE COOLING IN REFRIGERATION ENGINEERING
Authors: Doroshenko A.V., Lisohurska O.A.Educational and Research Institute Refrigeration, Сriotehnology and Eco-EnergyOdessa National Academy of Food TechnologiesRozum M.V.Odessa National Maritime University
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Abstract: The concept of creation of multi-stage evaporative coolers of gases and liquids based on multi-channel monoblock polymer structures was developed. The indirect types of coolers in normal and regenerative options are used as the basic elements in them. Natural limit of the cooling in such systems is the dew point of outside air, which significantly enhances the possibilities of the evaporative cooling technology in general, and allows us to solve a number of problems of the refrigeration and air conditioning equipment with a significant reduction of energy consumption for the process. Particular attention is paid to the problem of water vapor recondensation in the transition to multi-stage evaporative coolers. The theory of joint heat and mass transfer in indirect evaporative cooling was examined. The principle of design of individual monoblocks, as well as multi-stage blocks, was developed and recommendations to the design of a new generation of evaporative coolers were made. Preliminary analysis of the possibilities of the evaporative coolers applying to the solution of problems of air conditioning was made. |
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Keywords: Evaporative cooler, multi-stage scheme, monoblock, multichannel nozzle, joint heat and mass transfer, recondensation.
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ECONOMICS OF ENERGETICS
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ECONOMIC ASPECTS OF DESIGNING, CONSTRUCTION AND OPERATION OF MINI-CHP IN BELARUS
Authors: Kovalev I.L., (State Enterprise „Institute of Sistemic Research in Agro-Industrial complex of the Academy of Scieces of Belarus”),Kovalev L.I. (Private Institution ”Institute of Business activities”)
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Abstract: The article raised questions of efficiency of operation of CHP in industrial enterprises in Belarus, as well as the problem of cross-subsidies in the energy sector of the Republic and its negative impact on the economy as a whole. Data of the electricity tariffs for households and industrial consumers in Belarus and the countries the EU have been presented and analyzed. Main economic indicators and results of operation of a number of mini–CHP, which were built in Belarus over the last ten years, have been analyzed. The operating results have been compared with a view to economic efficiency of all investigated local energy facilities. |
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Keywords: CHP, rates, gas turbines, energetics, maintenance and repair, electric power supply, current power supply.
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ENERGY EFFICIENCY
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ENERGY MONITORING OF BUILDINGS OF UNIVERSITIES
Authors: Rozen V. P. National Technical University of Ukraine «Kyiv Polytechnic Institute»Tkachenko V. F., Cherkasy State Technological University
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Abstract: Publications for cluster analysis application in order to solve energy efficiency problems were analyzed. With the help of cluster analysis the cauterization of buildings of Cherkasy State Technological University is carried out. System-forming factors for clusters and dimensions for the calculation of energy intensity norms within a cluster have been determined. |
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Keywords: Energy efficiency, cluster analysis.
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Moiseeff F. - 65 Years!
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Ermuratsky V. - 75 Years!
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