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ELECTROENERGETICS
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ANALYSIS OF DEVELOPMENT OPTIONS FOR GENERATING CAPACITY IN THE REPUBLIC OF MOLDOVA
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 paperwork deals with analysis of scenario concerning integration of Moldova’s right bank power system to ENTSO-E. In the paperwork are proposed and analyzed different variants of generation capacity development on the territory of republic’s right bank considering tasks mentioned in the Energy Strategy of Republic Moldova by 2030. For every proposed variant of generation capacity development the analysis of normal modes regarding active power losses was performed for both in whole power system and separately in every of their elements with differentiation by voltage levels. There were performed the computation and estimation of coefficients of static stability reserve by active power and by voltage and also were estimated the import/export of electrical energy as well as were analyzed many other modes of indicators. As result of comparative analysis, the more technical effective variants (in author’s opinion) were selected. |
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Keywords: Reserve of power system stability, ENTSO-E, unified power system, static mode, losses of active power, generation capacity.
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RESEARCH OF THE INFLUENCE OF VARIOUS FACTORS ON THE ACCURACY OF DETERMINING OF PARAMETERS AND PLACE OF INSULATION DAMAGE IN THE ELECTRIC NETWORKS OF 6 TO 35 KV
Authors: Naraeva R.R. , Khusainov S.N. Southern Ural State University, Chelyabinsk, Russia
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Abstract: The present paper is devoted to the research of the method for determining the parameters and plot of insulation damage in the networks of 6 to 35 kV with isolated neutral on the basis of measuring the operating parameters of the network. In the considered three-phase circuit with a symmetric source of EMF and symmetric loading there was a damage of insulation in one of the phases. The calculations are carried out for the transmission line equivalent circuit with a branch line by means of node-potential method. An investigation of the influence of the magnitude of insulation conductivity in the place of damage of different sections of the network upon the accuracy of determining the insulation conductivity is conducted using the data from digital models. The research of this method is performed by advancing hypotheses about the place of damage and by considering the influence of the multiplicity of increasing insulation conductivity of the damaged section and accuracy class of measuring devices. |
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Keywords: Digital model, hypotheses of damage, total conductivity of insulation, active conductivity.
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ABOUT SOME FEATURES OF TRANSMISSION MODE FOR ACTIVE POWER OF ELECTRICAL LINE
Authors: Paţiuc V., Berzan V., Anisimov V., Cabac S., Postoronca S. Institute of Power Engeneering of the ASM
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Abstract: This paperwork examines the problem of maximum power transfer to the load of a long line mode change from idle line (XX ) to short-circuit ( SC). Load line changes from idle mode (IM ) to its short-circuit (SC ). The line length varies from zero up to a length equal to the physical length of the electromagnetic wave. As a method of research it is used the method of the complex amplitudes (MCA). As independent variables were examined her load line length and that the system per unit change in the band plus minus unit to unit , so . It enteritis that for the active character load of the active power input and power output of the line, so functions , and functions that characterize developments efficiency , power factor at the input line and the load power factor when the variable z. For these points to the notion of critical value of the load . It founds the effect of " recession " critical resistance values and functions şi , which is not found for the other functions considered - efficiency and power factor. Load reactive power compensation can help to increase power output only for lines with length smaller than ¼ wave length electromagnitice wave. In non-distortional lines, such effect is not observed. The paper work represents the general data transmission mode the maximum power lines of different lengths to the load, which varies from idle mode (IM) to short-circuit (SC) regime. These data can be used for preliminary analysis of the efficiency of the electrical lines at variable load. |
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Keywords: Electric power line, transmitted power, efficiency, power factor, method of complex amplitudes.
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INVESTIGATION OF ASYMMETRICAL MODES OF THREE-PHASE THREE–LEG TRANSFORMER WITH WINDINGS CONNECTION IN ZIGZAG
Authors: V.A.Bosneaga, V.M. Suslov Power Engineering Institute of Academy of Sciences of Moldova
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Abstract: Calculations and analysis were performed and specific characteristics of steady state asymmetric modes were investigated in three-phase three-leg transformer with zigzag diagram of windings connection, taking into account the electromagnetic coupling of the windings, located on different legs. Calculations and analysis were performed for the distribution transformer of 10/0.4 kV. The most characteristic steady state asymmetrical modes, which occur during different short circuits, were investigated, including those, associated with the occurrence of zero sequence magnetic flow. For the considered regimes 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: Simulation, asymmetric modes, three legs magnetic circuit, zigzag windings connections, zero-sequence magnetic flow.
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CHARACTERISTICS OF POWER SELF-COMPENSATED TRANSMISSION LINES EXTREMELY COMPACT 330-350 kV
Authors: Postolatii V.М., Suslov V.M., Power Engineering Institute of Moldova Academy of Sciences
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Abstract: The optimal configuration of phases placement of double circuit compact controlled self-compensated high-voltage power lines (KUSVL ) with the voltage of 330-500 kV at the condition of achieving of the maximum admissible value of the electric field tension on the surface of split phase at a given design was determined. The parameters of these lines at the extreme values of the angular shift (θ) between the circuits’ systems voltages were calculated. It was shown, that the surge impedance of KUSVL without special phase-shifting transformers (e.g. θ = 0˚) is minimal, and is equal (for each phase) for the option of 330 kV and wires 3AS-300/39 - 196 ohms, and for voltage of 500 kV and phase conductors 6AS-240/39 –162 ohms. The magnitude of transmission capacity of considered line (for both circuits) at rated voltage is maximal and equal to 1118 MW (for 330 kV line) and 3080 MW (for 500 kV line). At changing of line to the mode of angle θ = 180˚ (with special phase-shifting transformer) surge impedance is maximal and the transmission capacity minimal. Ratio of the maximal value of transmission capacity to the minimal (regulation range) reaches values of up to 1.5. |
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Keywords: Compact, controllability, self-compensation, power transmission line, surge-impedance power, design optimization, the electric field strength.
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POTENTIAL DISTRIBUTION IN VICINITY OF TRANSMISSION LINE SUPPORT
Authors: Patsiuk V. Institute of Power Engineering of the Academy of Sciences of Moldova
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Abstract: The paper examines a new approach to finite volume method which is used to calculate the electric field of spatially inhomogeneous three-dimensional environment. The Dirichlet problem is formulated and the computational grid is constructed on the base of space partition, which is known as Delaunay triangulation with the use of Voronoi cells. To calculate the potential and the electric field strength in the vicinity of the electric line support the numerical algorithm is proposed. We have developed the algorithm and the corresponding software using Matlab application. There are presented some numerical results of calculations of the distribution of potential and of the electric field strength. |
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Keywords: Electric field , inhomogeneous medium, potential, electrical field strength, numerical method.
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RENEWABLE ENERGY SOURCES
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AERATION OF THE ICE-COVERED WATER POOLS USING THE WAVE FLOW AERATOR
Authors: Solomin E.E, Sirotkin E.A., SolominE.V. South-Urals State University
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Abstract: This article describes the technical advantages and economic benefits of the ice-covered pool aeration plants consuming power from renewable energy sources. We made a comparative evaluation of the wave flow-aeration method and other methods of pool aeration. We showed the indexes and the characteristics of the wave flow-maker for aeration of ice-covered pools on the territory of Russia. We also made calculations of the economic benefits of aeration plants using the devices converting renewable energy. The project can be scaled and extended to the territory of the CIS, Europe, USA and Canada in the changing climate conditions and the variety of feed reservoirs around the world. |
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Keywords: Aeration, wind power, agro-industrial complex.
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ENERGY EFFICIENCY
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ENERGY AUDIT AS TOOL FOR DECREASING OF ENERGY CONSUMPTION
Authors: Tirshu M., Zaitsev D., Golub I. Institute of Power Engineering of Academy of Sciences of Moldova
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Abstract: The paper presents results of the energy audit for seven public organizations. Audits were performed in 2013 by the staff of the Institute of Power Engineering of the ASM. The staff is authorized in the field of electricity and thermal energy. Four energy audits were for energy efficiency in buildings; two energy audits were for efficient public lighting system and one for efficient lighting system within the organization. For each organization were highlighted major problems which lead to increased energy consumption and proposed several measures that help reduce energy consumption and reduce CO2 emissions. Also describes methods for the measurements and the equipment used. It presents characteristic problems typified by object class and how to overcome them. Energy consumption is determined for both - baseline energy consumption and after implementing the proposed measures. Also, the necessary investments, the results obtained after investments and the payback periods for each proposed measures as well as a whole are presented. |
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Keywords: Energy audit, efficiency measures, energy consumption, CO2 emissions.
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WELDING INSTALLATION WITH REDUCED IMPACT ON THE NETWORK
Authors: Tirsu M.S., Zaitev D.A., Uzun M.N. Institute of power engineering of Academy of Sciences of Moldova
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Abstract: This paper offers a new technical solution to implement arc welding installation. Existing electric arc welders have a significant impact on consumers that are connected near the connection point of it. This effect is greater the longer the feeder. If the installation is connected to the end of the feeder, the impact on neighboring consumers is so large that can be damaged appliances. The proposed technical solution is based on the idea of using the battery as a buffer. The battery is designed so that its capacity was sufficient to meet the instantaneous current peaks that occur during operation. Along with this, in the proposed technical solution, an innovative element is a current pulse source. The novelty lies in the special algorithm of this current source. The proposed algorithm allows the power consumption of the network in a controlled manner and without abrupt jumps. |
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Keywords: Welding, electric arc, installation, pulse current source.
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HEAT AND POWER ENGINEERING
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ENERGY SUPPLY OF COMMERTIAL GREENHOUSE WITH THE GAS DRIVEN HEAT PUMP part II
Authors: Sit M.L., Ioisher A.A., Andronaty N.R., Burchiu V.I., Sit B.M. Institute of Power Engineering of the Academy of Sciences of Moldova
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Abstract: In this article a scheme of connection of heat exchanger for utilization of heat of flue gases to evaporator is proposed. In proposed scheme is ensured the minimum power of ventilator for air’s feeding to the evaporator of heat pump and compensation of pulsations of temperature of flue gases and pressure of ventilator. It is shown how to optimize parameters of heat exchanger in conditions of minimum of dissipation of energy with utilization of value of entransy. It is elaborated a scheme of coordinated control system of hydraulic transmissions, that transfers power on compressor of heat pump and electrical generator. |
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Keywords: Heat pump, recuperator, coordinated control system, carbon dioxide, entransy.
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CALCULATION OF INTERNAL THERMAL RESISTANCE OF WORKING BODIES OF PACKEDBED SENSIBLE AND LATENT HEAT STORAGES
Authors: Ermuratschii V.V., Gritsay M.A. Institute of Power Engineering of Academy of Sciences of Moldova
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Abstract: The paper considers the problem of calculating values of the internal thermal resistance of a packed bed sensible and latent heat storages working bodies. The methodic calculation of this resistance for bodies with solid, liquid substance and phase-change materials is offered. Being based on the theory of a regular thermal mode, formulas for calculation of internal thermal resistance of the bodies having the form of a sphere, the cylinder and a paralle-lepiped are obtained. For bodies with liquid substance this resistance is in view of a wall of vessels and resistance of a boundary layer at natural convection of liquids. In the case of substances with a phase transition heat resistance zones with different states of aggregation shall be determined separately. Electro-thermal model contains of the four thermal resistances, two heat capacity and single voltage source. Internal thermal resistance of solids can be considered as a constant parameter. For bodies of liquid and phase change material internal thermal resistance depends on their thermal state. Therefore, these values should be determined in the calculation processes of their heating or cooling. |
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Keywords: Electro-thermal model, sensible and latent heat storages, internal thermal resistance, phase change materials.
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