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  Problemele energeticii regionale

E-Journal №3(35)2017



1 Characteristics of the Phase-shifting Transformer Realized According to the "Polygon" Connection
Authors: Kalinin L.P., Zaitcev D.A., Tirshu M.S., Golub I.V. Institute of Power Engineering of the Academy of Sciences of Moldova Kishinau, Republic of Moldova
  Abstract: The object of the study is a two-transformer phase-shifting device with a span of adjustment of the angle of phase shift . In order to determine the energy characteristics of the investigated device, it has been put the scope to study the regime's parameters, performing adjustment of the angle of phase shift. This was made possible due to the use of the thyristor key for 10 positions and the low of it’s switching. The model was developed for a series of computational experiments for the cases of: idle, short circuit and loaded regime. A comparative analysis of the technical characteristics of the studied device, with the phase-reversing transformers investigated earlier has been carried out. The novelty of the work consists in the development of a scheme of a two-transformer phase regulating device. The additional winding of the magnetizing transformer was connected on an opposite side to the winding of the phase-shifting transformer. It has been achieved a reduction in the value of the magnetic induction in the core, as well as an increase of the stability in the process of adjusting the angle of phase shift. The analysis of the obtained characteristics of the device made it possible, by comparison with the available variants of existing circuits, to conclude that the developed one was of increased technical efficiency. The proposed technical solution decreased the installed capacity of the equipment, which in turn lead to a reduction of the weight and size indices and, as a consequence, of its cost.
  Keywords: phase shifting transformer, angle of phase shift, design capacity of the device.
2 Stabilization of Voltage Parameters of Induction Generator Excited by a Voltage Inverter
Authors: Padalko D.A. National Research Tomsk Polytechnic University Tomsk, Russian Federation
  Abstract: The article reveals the operational aspects of induction generator. Methods for stabilization of induction generator (IG) parameters under inverter excitation are investigated. The study was carried out using mathematical description and simulation modeling in MATLAB Simulink. The paper provides analysis of causes of generated voltage amplitude and frequency displacement when the loading condition and the rate vary. Due to the parametric resonance nature of IG self-excitation, the author introduces the expression that allows estimating the capacitor capacitance required to maintain the generation process, depending on the rotor speed of electric machine, load nature and rate. Based on the studies, it was proved that it is possible to stabilize the IG voltage parameters by maintaining the magnetizing circuit inductance Lm at the constant level., and realizing a control law close to U/f = const. The study proves that using the inverter together with the voltage regulator allows ensuring the quality of electricity corresponding to modern standards. The necessity of problem solving of the required quality of the voltage by the harmonic component for the exciter - inverter with PWM is shown. The prospects of the power generation system based on induction machine (IM) with a semiconductor frequency converter, which serves as an adjustable supplier of capacitive current for IM for autonomous objects, are substantiated. The use of semiconductor frequency converters makes it possible to provide high stability of the output voltage parameters and good speed of the mechatronic generation system with an asynchronous machine.
  Keywords: induction generator, inverter excitation, voltage parameters stabilization, mathematical modeling, parametric resonance, self-excitation process.
3 Electronic Power Transformer for Power Distribution Networks
Authors: Ermuraсhi Iu.V. Institute of Power Engineering of the Academy of Sciences of Moldova Chisinau, Republic of Moldova
  Abstract: Reducing losses in electricity distribution networks is a current technical problem. This issue also has social and environmental aspects. As a promising solution one can examine the direct distribution from the medium voltage power network using new equipment based on the use of power electronics. The aim of the paper is to propose and argue an innovative technical solution for the realization of the Solid State Transformer (SST) in order to decrease the number of energy transformation stages compared to the known solutions, simplifying the topology of the functional scheme with the reduction of production costs and the loss of energy in transformers used in electrical distribution networks. It is proposed the solution of simplifying the topology of the AC/AC electronic transformer by reducing the number of passive electronic components (resistors, inductors, capacitors) and active (transistors). The inverter of the SST transformer ensures the switching mode of the transistors, using for this purpose the inductance of the magnetic leakage flux of the high frequency transformer. The robustness of the laboratory sample of the SST 10 / 0.22 kV transformer with the power of 20 kW was manufactured and tested. Testing of the laboratory sample confirmed the functionality of the proposed scheme and the possibility of switching of the transistors to at zero current (ZCS mode) with the reduction of the energy losses. In the proposed converter a single high-frequency transformer with a simplified construction with two windings is used, which reduces its mass and the cost of making the transformer. The reduction in the manufacturing cost of the converter is also due to the decrease in the number of links between the functional elements.
  Keywords: electronic transformer, electronic keys, commutation mode ZCS, stabilization of output voltage, coefficient of distortion.
5 Optimal Solutions for Load Sharing between Units of a Combined Heat and Power Plant
Authors: Shchinnikov P. A., Borush O.V., Zykov S.V., Mikhaylenko A.I. Novosibirsk State Technical University Novosibirsk, Russian Federation
  Abstract: The article presents the optimization method of load division between combined heat and power plant units. The method used the power unit division into functioning parts and the differential-exergy method. This method allowed presenting the unit as a structural diagram where exergetic subsystems are fuel supply, steam generator, turbine, generator and electrical equipment, water supply and regeneration, heat supply to the consumer. The differential-exergy method was based on a combination of exergy analysis and optimization method of economic efficiency criteria using uncertain Lagrange multipliers. The use of the exergy function of goal allowed avoiding the problem of division of fuel costs for each type of product that was important at optimization. The optimization criterion, its parameters and limitations were developed as well. These parameters can extend traditional technical and economic analysis of the combined heat and power plants operating mode, as they take into account thermodynamically rigorous division of fuel costs between heat and electric power at their complex production on the combined heat and power plants. The use of the differential-exergy method in optimizing the load distribution of the power units of the combined heat and power plants makes possible obtaining of fuel savings of 1.5 to 3%. It has been shown that if the parameters of power units deteriorate, the application of the method makes it possible to have the best performance of the power plant when it is compared with functioning of combined heat and power units at proportional loading.
  Keywords: optimization, exergy, criterion, power unit, distribution, load.
6 Combustion of Solid Fuel in a Vortex Furnace with Counter-swirling Flows
Authors: Redko A.A.1, Redko I.A.2, Redko A.F.1 1Department of heat and gas supply, ventilation and the use of thermal waste energy Kharkiv National University of Construction and Architecture Kharkov, Ukraine. 2Department of Exploitation of gas and heating systems Kharkiv National University of Urban Economy by O.M. Beketov Kharkiv, Ukraine.
  Abstract: The results of computer simulation of the processes of incineration of low-grade solid fuel-pulverized peat with a moisture content of 40%, an ash content of 6% are given. It has been determined the fields of distribution of temperature, velocity of gases and particles in the volume and at the outlet from the furnace. The three-dimensional temperature distribution in the combustion chamber indicates high-temperature combustion of peat particles at temperatures above 1700°C with liquid ash removal in the lower part of the furnace. It has been determined that when the furnace is cooled, it is not ensured combustion of the fuel completely. The value of the swirling flow rate at the outlet from the furnace (up to 370 m/s) ensures the efficiency of separation of fuel particles, reducing heat losses from mechanical underburning. It is determined that the concentration of oxygen is close to zero over the entire height of the furnace, at an outlet from the furnace the oxygen concentration is 5...6%, since oxygen is supplied with excess (αв=1,2). The results of a numerical study showed that the diameter of peat particles affects the process of their combustion: coke particles with an initial diameter of 25 mkm to 250 mkm burn out by 96%. With an increase in particle diameter up to 1000 mkm, the degree of burn-out of coke decreases, but at the same time their removal decreases. It is shown that the furnace ensures the completeness of combustion of peat particles of peat 99.8%, volatiles is 100%.
  Keywords: numerical simulation, combustion processes, solid fuel, furnace.
8 Increase of the Integration Degree of Wind Power Plants into the Energy System Using Wind Forecasting and Power Consumption Predictor Models by Transmission System Operator
Authors: Manusov V.Z., Kholdonov A.A., Boiko K.N., Khaldarov Sh.K. Novosibirsk State Technical University Novosibirsk, Russian Federation
  Abstract: Wind power plants’ (WPPs) high penetration into the power system leads to various inconveniences in the work of system operators. This fact is associated with the unpredictable nature of wind speed and generated power, respectively. Due to these factors, such source of electricity must be connected to the power system to avoid detrimental effects on the stability and quality of electricity. The power generated by the WPPs is not regulated by the system operator. Accurate forecasting of wind speed and power, as well as power load can solve this problem, thereby making a significant contribution to improving the power supply systems reliability. The article presents a mathematical model for the wind speed prediction, which is based on autoregression and fuzzy logic derivation of Takagi-Sugeno. The new model of wavelet transform has been developed, which makes it possible to include unnecessary noise from the model, as well as to reveal the cycling of the processes and their trend. It has been proved, that the proposed combination of methods can be used simultaneously to predict the power consumption and the wind power plant potential power at any time interval, depending on the planning horizon. The proposed models support a new scientific concept for the predictive control system of wind power stations and increase their degree integration into the electric power system.
  Keywords: autoregression, Fuzzy Systems, regression model, least squares method, wavelet data analysis, mean-square error.
9 The Qualification of Electricity Production in High Efficiency Cogeneration for the Access to the Support Scheme through Green Certificates
Authors: Atanasoae P., Pentiuc R. D. Faculty of Electrical Engineering and Computer Science “Stefan cel Mare” University of Suceava Suceava, Romania
  Abstract: The promotion of high efficiency cogeneration is a priority of the European Union, given the potential benefits of cogeneration relating to primary energy savings, avoiding network losses and reducing emissions of greenhouse gases. The paper presents the manner of determining the amount of electricity generated in high efficiency cogeneration for access to the support scheme through green certificates. The support scheme for the promotion of cogeneration is based on useful heat demand and primary energy savings compared with separate production of electricity and heat. We examine a cogeneration heat and power plant with ORC technology and biomass fuel, which have the technical characteristics in the nominal conditions of 1.3 MWe (electrical power) and 5.4 MWth (thermal power). We also propose an algorithm for determining the useful heat, who takes into account the operational requirements of the analysed CHP unit.
  Keywords: combined heat and power (CHP), organic Rankine cycle (ORC), support schemes, green certificates, high efficiency cogeneration, biomass, renewable energy sources (RES).
10 Development and Ecological-Energy Comparative Analysis оf Vapor Compression and Solar Absorption Schemes of Air Conditioning Systems
Authors: Doroshenko A.V., Antonova A.R., Ivanova L.V. Educational and Research Institute of Refrigeration, Сriotehnology and Eco-Energetics Odessa National Academy of Food Technologies, Odessa, Ukraine
  Abstract: The mission of the research included the following objectives: the development of new circuit decisions for the alternate refrigerating systems based on the use of an open absorptive circuit and on the use of solar energy for absorbent solution regeneration; an assessment of the energy and envi-ronmental characteristics of the developed systems; obtaining of the experimental data for an assess-ment of the principal capabilities of the proposed new solar air-conditioning systems. New principles for design of heat and mass transfer equipment in the version with a movable packing of heat exchange elements (fluidized bed packing "gas - liquid - solid body") placed in the packed bed were developed, which allows self-cleaning of the working surfaces and walls of the heat and mass transfer equipment HMT. This new solution, when working with outdoor air and solutions of absorbents, seems to be a fundamentally important condition for maintaining the working capacity of solar absorption systems. The new schemes of absorber with internal steam cooling allowing the improve-ment of the new scheme of the alternate refrigerating system were developed. Comparative analysis based on the methodology of the "Life Cycle Assessment" (LCA) showed that new, developed solar systems provide the considerable decrease in energy consumption, their use leads to the decrease of exhaustion of natural resources, influences less global climate change.
  Keywords: solar systems, drying of air, heat-mass-transfer apparatus, fluidized bed packing, absorption, desorption, evaporative cooling.
11 The Construction of Holonic Infrastructure of Intelligent Networks in the Smart Grid Concept with a Two-Way Flow of Energy
Authors: Manusov V.Z., Khasanzoda N. Novosibirsk State Technical University Novosibirsk, Russian Federation
  Abstract: The paper deals with the intelligent network modes based on the Smart Grid concept with the function of two-way energy flow, both from the power system and from its sources of distributed generation. The expanded interpretation and the meaning of the intellectual network concept - Smart Grid - is proposed, based on its abbreviation, which determines the system criteria for its purpose. A new concept is introduced and new definition - Holonic Approach - Smart Grid concept. A new term has been introduced: - "Generating Consumer-Holon" (GC-Holon), which means the ability of an electric consumer to independently generate energy using renewable sources, store it, exchange energy with other similar GC-Holon and the main generating system. In connection with this, the concept of a generating consumer has been introduced. To construct an intelligent network, a holonic structure based on a set of holons (subsystems) is used. The holonic structure assumes subsystems of different nature, located at different levels of aggregation, interconnected in order to form a hierarchy of self-regulating holons, called Holarchy. According to A. Koestler, holons are simultaneously, both whole and partial. They are basically autonomous, which allows them to ensure their existence independently. The two-way energy flow for the holonic structure assumes the possibility of generation and storage of energy due to the internal structure of the electric consumer. The infrastructure of an intelligent network and its applications are considered. A mathematical model of bilateral electric power consumption by a generating consumer is proposed, taking into account tariffs and pricing. This allows you to flexibly regulate energy flow and align the load schedule, minimizing financial expenses for consumed energy.
  Keywords: intellectual network, Smart Grid, holon, holarchy, renewables, two-way of energy, energy store.
12 Tracking Systems for Orientation of Solar Panels and Optimization of their Positioning Using Three-coordinate Platforms
Authors: Chalbash O.H. Institute of Power Engineering of the Academy of Sciences of Moldova Chisinau, Republic of Moldova
  Abstract: Two-coordinate platforms equipped with orientation systems are 40-45% more effective than stationary installations. However, there are other factors affecting the efficiency of solar installations. In particular, the shading on the panels’ surfaces when panels, located in rows, are casting shadows on each other. This negatively affects the efficiency of photovoltaic installations. Previous experience in the design of photovoltaic systems shows that neither stationary platforms nor two-coordinate installations completely eliminate energy losses due to shadow formation. The only way to mitigate this negative impact is to increase the distance between the panels. At the same time, and the density ratio (the ratio of the panel area to the area of the land) does not exceed 0.2. Our goal is to develop kinematic schemes and software control systems for three coordinate platforms that can avoid shadow formation on panels placed in constrained spaces. The result of our work is a numerical method that solves the optimization problem for controlling the motion of a set of platforms and a rational kinematic scheme for three coordinate platforms. This problem is especially relevant for solar photovoltaic systems located on space stations. In space, the changes in temperature between shaded and shadow-free sections of panels is enormous, due to temperature stress, the panels get destroyed and require expensive repairs. Three-coordinate tracking can reduce the surface occupied by solar panels by about 3 times compared to the currently used solutions and increased module placement densities from 0.2 to 0.6.
  Keywords: tracking systems of solar installations, control system for monitoring the positioning of solar panels, optimization methods, platform’s kinematic schemes.
14 Development of Captive Expense Regulation Model of Siberian Electricity Distribution Companies
Authors: Chernov S.S., Kolkova N.A. Novosibirsk State Technical University Novosibirsk, Russian Federation
  Abstract: Russian electricity distribution business is a kind of natural monopoly activities, where different ways of state control, including tariff formation are applied. The problem of high setting of tariffs for some electricity distribution companies and the low setting for another one takes place in the sphere of tariff formation in Russia. This does not allow forming the financial basis for stable development of the electricity distribution sector. This problem had been solved by means of comparison study of expenses of electricity distribution companies (benchmarking study). The research subject was tariff formation system of electricity distribution companies of the Russian Federation. We examined the factors exerting influence on captive expense regulation for developing model of efficiency level of captive expense regulation. In the process of studying the foreign experience of benchmarking electricity companies and the peculiarities of the work of electricity companies in Siberia, a list of factors had been determined for constructing a regression model of controlled expenditures. Using the data on eight indicators of operation of production assets of 51 electric grid companies of Siberia for 2014-2016, it became possible to form a model for the effective level of captive expense. We argued that factors such as the cost of the region's market basket, the actual volume of energy, and the level of electricity losses have the greatest impact on the of captive expense of companies in the Siberia Federal District. The article demonstrates the new model of captive expense regulation of electricity distribution companies of Siberia.
  Keywords: electricity distribution company, tariff formation, benchmarking, X–efficiency, electricity distribution companies’ expenses.
15 Scenario Approach to the Planning of the Production Activities of the Enterprise with a Discrete Type of Production (for Example, Electrical Engineering Industry)
Authors: Krylova E.V. Novosibirsk State Technical University Novosibirsk, Russian Federation
  Abstract: In conditions of global economic instability the success of electromechanical enterprises depends on their ability to react quickly to challenges of external environment. In order to create background and conditions for this ability the given enterprises refer to manufacturing activity planning, using a probabilistic approach based on forecasts that may not be true. The question of provision of more complete consideration of various internal and external factors and acceleration of decision making process and reaction to changing business environment arises before the organizations that concern more effective scheduling policy. International practice of solving such problems generally leads to qualitative discussion, whereas quantitative assessment of impact of control parameters of enterprise is not practically used, because there is no one systematic approach to manufacturing activity planning. On the basis of studying of international practices methodical guidelines of scenario approach to manufacturing activity planning with mathematical modeling of economics of producer price on electromechanical enterprises have been developed, which reasonably could be used with reference to and interaction with enterprise manufacturing program. The described approach allows solving planning problems iteratively in real-time mode concerning profit maximization, to form producer prices, to divide overhead costs according to the type of products and carry out cost accounting according to the type of a product, and it will provide functional interaction between factors and performance indicators.
  Keywords: planning, production activity, enterprise, uncertainty, sustainability, scenario, production program, economic-mathematical modeling, forecasting, economic impact.
  Keywords: corigendum
DOI: 10.5281/zenodo.1188811
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