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  Problemele energeticii regionale

E-Journal N4(52) 2021



1 Features of Forecasting Reliability of 6—10 kV Overhead Electric Lines According to Statistics of Their Failures and Reconditionings
Authors: Basmanov V.G., Kholmanskikh V.M. Vyatka State University Kirov, Russian Federation
  Abstract: This work is aimed at forecasting justification of the failure time of the 6—10 kV overhead electric lines (OEL) during the normalized period in its operation based on comparison with the statistics of failures and reconditionings on the previous intervals with the use of the OEL availability function, statistical availability coefficient, normalized forecasting interval and the accepted values of the availability coefficient on the forecasting interval. To achieve the goal set the OEL is described as an object of a multiple action, its failure and reconditioning flows are accepted as the simplest Poisson, and for the theoretical analysis of the variation character in the availability coefficient, the probability theory methods along with a mass service were used. The most significant result is justification of the use for the forecasting of the OEL failure time of a new convenient exponential expression of its availability function on the normalized period of time being forecasted. Unlike the accepted in the theory of reliability the availability function with two parameters T and Tr.av (average times of work and reconditionings), the proposed expression uses one parameter of distribution (virtual non-failure operating time). The significance of the results obtained consists in that controlling the dynamics of the variation in the statistical coefficient of availability of the OEL on the previous time intervals makes it possible to forecast its failure time during the forthcoming normalized periods of operation.
  Keywords: overhead lines, coefficient of technical availability, forecasting normalized interval, virtual non-failure operating time, confidence probability.
2 Energy Efficient Control by the Group of Oil Pumping Stations Operation
Authors: Kaniuk G. I., Mezeria A. Yu., Kniazeva V. N., Fursova T. N., Blyznychenko E. N. Ukrainian Engineering Pedagogics Academy Kharkov, Ukraine
  Abstract: This work is devoted to intensification of the power efficiency of computerized systems of con-trol by the pumping units group of oil pumping stations of the main lines. The criterion of the energy efficiency is a minimum total energy loss. The goal set can be reached by the develop-ment of algorithms of the energy efficient control. The most important scientific result based on the identification of the mathematical models of the objects controlled is the efficient algorithm for controlling the group of oil pumping units. It allows determining in real time the operation modes of separate pumping units, upon which the total energy losses will be minimal. The sig-nificance of the results obtained consists in the energy losses decrease across the main oil pipe-line during the combined control by the pumping units groups. Their practical significance con-sists in decreasing the cost of oil transportation at the expense of decreasing the energy con-sumed by the pumping units. The main stages of plotting the modes maps were presented of the efficient operation of the pumping units based on the definition of the necessary rotation fre-quencies and positions of the regulating valves. Experimentally was performed the analysis of the operation modes of the pumping unit using different methods for productivity regulation, and their comparative energy efficiency was shown. The experimental data extrapolation was carried out, and, on its basis, the possible economic effect was determined brought by the use of the energy-conserving systems of the controlling the group of pumping systems.
  Keywords: pump, oil-pumping station, computerized system of control, energy saving.
3 Effect of Individual Sulfide on the Stability against Oxidation of Transformer Oil and Its Electrical Parameters
Authors: Gainullina L.R. Kazan State Power Engineering University Kazan, Russian Federation
  Abstract: This study is devoted to the improvement of the transformer oil quality, using a new inhibiting additive, since the extensively used inhibitory additive ionol is sensitive to organosulfur compounds of sulfur oils. From the earlier works, the organosulfur compounds are known to affect ambiguously the transformer oils characteristics. Therefore, it was of interest to study the individual sulfides as the inhibitory additives. The goal was achieved by the researches with the use of the model mixtures consisting of the selectively purified transformer oil (free from ionol) along with the individual sulfides, decylcyclohexylsulfide and decylfenylsulfide, at concentration of 0.5 %, Their effect on stability against oxidation of the selectively purified oil, on its electric strength and tangent of the dielectric losses’ angle was studied. The primary results obtained were, firstly, the rate slowing down of water formation in oil and of water-soluble acids formation in oil upon its oxidation in the presence of the individual sulfides, and, secondly, an increase in the electric strength and decrease in the dielectric losses compared to the transformer oil, containing ionol. It was established that decylcyclohexylsulfide inhibitory properties are stronger compared to those of decylfenylsulfide, which was testified by less quantities (by 1.8 times) of the water formed and of water-soluble acids (by 2.22 times). The introduction to oil of 0.5 % decylcyclohexylsulfide and decylfenylsulfide increased the oil electric strength, correspondingly, by 2.6 and by 5.5 times, upon water concentration in oil equal to 15·10-2 g/kg. The significance of the results obtained is in improving the transformer oil quality produced from the sulfur oils with the use of a novel additive.
  Keywords: dielectric strength, dielectric loss, individual sulfide, additive, oil insulation, decylcyclohexyl sulfide, decylphenyl sulfide.
4 Development of the Method for Predicting and Calculating the Operation of Sorption Systems for Cleaning the Generator Gas based on Dolomite Use. Part II
Authors: 1Malko M.V., 2Vasilevich S.V., 3Mitrofanov A.V., 3Mizonov V.E. 1Institute of Power Engineering of the National Academy of Sciences of Belarus, Minsk, Republic of Belarus, 2Belarusian State Academy of Aviation, Minsk, Republic of Belarus, 3Ivanovo State Power Engineering University, Ivanovo, Russian Federation
  Abstract: At present, instead of a direct combustion of solid fuel, its thermochemical conversion is exten-sively used to produce a generator gas. The use of this technology is connected with the need for gas purification. One of the promising and widely spread sorbents for the purification of the generator gas is dolomite, whose particles compose the active component of the bed filters. Forecasting the technological characteristics of the functioning of the bed filters of a various de-sign is an extremely urgent task. The objective of the study is to develop a method for forecast-ing and calculating the operation of sorption systems for purification of the generator gas based on dolomite. It is achieved by constructing and verifying a mathematical model of the function-ing of the bed sorption filter with a radial-axial flow pattern of the generator gas through the do-lomite filling. The Markov chains theory of a mathematical apparatus is used to design the one-dimensional mathematical model of the process with discrete space and time. The main recurrent balance ratio is formed at each calculation step taking into account the current characteristics of the process, which makes the model nonlinear. The significance of the research is that an approach to the problem of increasing the reliability of the description and reliability of forecasting technological processes in a bed filter was proposed based on the construction of mathematical models of these processes, in which the filter is considered as a system with distributed characteristics, and the calculation was based on local exchange potentials between particles and gas.
  Keywords: generator gas, dolomite, thermal decomposition, sorbent, thermogravimetric analysis, kinetics of decomposition, generator gas purification system.
5 Decreasing the Weight-Size Parameters of Gas-Steam Turbine Plant by Increasing the Efficiency of Thermodynamic Processes in the Condenser
Authors: Bortsov O.S., Shevtsov A.P. Admiral Makarov National University of Shipbuilding Мykolaiv, Ukraine
  Abstract: The aim of this work is decreasing the weight-size parameters of the contact gas-steam turbine plant and contact condenser elements by increasing the efficiency of thermal-gas dynamic processes of condensation through rational irrigation of countercurrent gas-steam flow. To achieve the goal the total efficiency of water-return drops ranging from 0.1 to 1 mm at different initial velocities from 5 to 35 m/s emitted by the multi-nozzle sprinkler was determined by mathematical modeling of the liquid droplet movement processes, heat and mass transfer between the liquid droplet and gas-vapor mixture, and gas-vapor mixture pressure loss. The effect of increasing the gas-steam mixture velocity from 3.3 to 6 m/s on the overall efficiency of water return was determined. The novelty of the obtained results was defined by an increase in the water return into cycle from 12 to 13% with a droplet diameter of 0.3 -- 0.4 mm and the initial velocity from the sprinkler of 5--10 m/s. The velocity of the mixture was to 6 m/s at rational correlations of the initial velocity of the droplets’ escape, which increased the total amount of heat withdrawn to 11%. The positive effect conditions of irrigation processes on thermogasdynamic and weight-size parameters of the condenser elements for the contact gas and steam turbine plant at full pressure recovery coefficients of over 0.967 were substantiated. The most significant result was the reduction of the weight-size parameters of the marine infrastructure object power plant from 8 to 19%.
  Keywords: circulating water, gas-steam flow, power plant, sprinkler, return of water, heat and mass transfer, specific power rating.
6 Matrix Method for Modelling of Multicomponent and Multistream Energy Systems and Installations of Thermal Power Plants
Authors: Barochkin A.E. Ivanovo State Power Engineering University Ivanovo, Russian Federation
  Abstract: The aim of this work is to increase the operational efficiency of the multicomponent multithreaded power units and systems of the TPP using modeling, calculation and optimization. The goal is achieved by solving the following tasks: development of the tasks’ classification system and a unified methodology for the mathematical description of energy formation and mass flows’ processes in multicomponent and multithreaded power units of the TPP; development of a model of a steam turbine power unit; development of a model of heat and mass transfer processes in multi-stage multistream multiphase systems. The most significant results obtained were: the developed unified methodology for the matrix description of the processes of energy and mass flows’ formation in multicomponent multistream energy systems of the TPP. Within the framework of the proposed methodology, a model of a steam turbine power was developed; model solutions were obtained and analyzed in order to calculate the energy characteristics of a heating turbine unit, the reliability and validity of the proposed approach was shown, a mathematical model of multistream multi-stage heat exchange systems were developed. The significance of the results obtained consisted in the development of a simple but informative mathematical model of a thermal power plant turbine generator and a model of multistream multi-stage heat exchange systems, each stage of which can have an arbitrary number of input and output flows with a possible phase transition in heat carriers.ave an arbitrary number of input and output flows with a possible phase transition in heat carriers.
  Keywords: matrix methodology of modeling, phase transition, classification of problems, contact apparatus, multicomponent multistream systems, inverse problem, numerical experiment.
7 Aerodynamic Characteristics of the Combustion Process of Sawdust in a Vortex Furnace with Counter-Swirling Flows
Authors: 1Dzhyoiev R.L., 1Redko A.A., 2Redko I.A., 1Pivnenko Yu.A., 1Burda Yu.A., 1Gvozdetskii A.V., 1Alforov S.A. 1Kharkiv National University of Construction and Architecture, Kharkiv, Ukraine 2Ukrainian State University of Railway Transport, Kharkiv, Ukraine
  Abstract: The aim of this work is to study the working processes of burning the low-quality fuels, namely, the saw dust in the swirling-type furnaces with an opposite twisted motion of the air. The goal was achieved using the physical and mathematical modeling of the flows interaction. The article presented the results of numerical study of aerodynamic characteristics of burning the saw dust in the swirling-type furnace with the opposite twisted air flows. For the research, the facility was used for the saw dust burning with the air supply into the lower and upper zones of burning. The most essential result of the work was modeling of the working process at the ratio of the flows of the primary air and secondary air without the fuel admixture, equal to 0.2. The tangential rate of the flow changed according to the horizontal sections from 3-5 m/s to 40-42 m/s and with respect to the furnace height from 51 m/s to 30 m/s. The average angular rate of the mixture changed relatively the furnace height in the ranges of 171-500 l/s to 100—300 l/s. The significance of the results obtained consists in determination of the possibility of increasing the efficiency of the work of the furnace facilities at the expense of the introduction of the primary and secondary air flows. In this situation, the optimal ratio of consumptions of primary and secondary air was 0.2. Thus, in this work the consumption of primary air was 1.285 kg/s, the consumption of the secondary air was 0.255 kg/s.
  Keywords: burning of fuel, swirling-type furnace, particle motion, distribution of pressures in furnace, rate of fuel-air mixture.
8 Development and Approbation of Methodology Aimed to Define the Reasons for Turbine Unit Capacity Limitation Based on the Specified Mathematical Model of its Condenser
Authors: Shempelev A. G. Vyatka State University Kirov, Russian Federation
  Abstract: The purpose of this work is to develop and test the methodology of elucidation of the reasons for turbine unit capacity limitations based on a mathematical model of its condenser. This pur-pose is achieved by using a mathematical model of the condenser as part of the developed methodology, taking into account the separate effects of contamination of the heat exchange surfaces, air suction into the vacuum system and the operating mode of the main ejector. Based on operational data sampling, the value of the limiting pressure in the condenser, excess of which leads to limitation of turbine unit capacity, was determined. It was established that the cause of power limitation is the abnormal operation of the main ejector due to inadmissible high temperature in the intermediate cooler of its first stage. For regimes that were not pressure-limited, using a mathematical model, the degree of tubes contamination, its influence on the condenser pressure and the power generated by the turbine unit, and the influence of actual air suctions on the condenser pressure were determined. The most important result of the study is to determine the possibility and feasibility of using the developed and tested methodology for solv-ing similar problems for any type of turbine unit equipped with a condenser. The significance of the work lies in the fact that the proposed approach expands the possibilities of using mathemat-ical models of this class in terms of solving such problems.
  Keywords: steam turbine, capacity, condenser, main ejector, limitations, condenser pressure, mathematical model of a condenser.
9 Analysis of Efficiency upon Enhancing the Fuel Combustion Completeness in the GTU Burners Using Fuel Gas Heating up
Authors: Pekov A.P., Bachev N.L., Shilova A.A., Matyunin O.O., Betinskaya O.A. Perm National Research Polytechnic University Perm, Russian Federation
  Abstract: One main characteristic of the gas turbine unit (GTU) burner is its fuel combustion completeness, which affects directly the efficiency of the power plant along with CO and unburnt hydrocarbons CnHm emissions. The aim of this work was the research on the application of the fuel heating-up as an alternative method for increasing the fuel combustion completeness and controlling the emission of harmful agents. This goal is achieved by obtaining experimental data on the emissions of CO and NOx at different temperatures of the fuel gas supply to the combustion chamber. The most significant result of the work is the experimentally confirmed possibility of increasing the combustion efficiency (decreasing CO) by heating the fuel gas while maintaining constant gas-dynamic characteristics of the chamber. The significance of the results obtained consists in the experimental confirmation of the combustion quality control only by heating the fuel gas without changing the operating and design characteristics of the combustion chamber. The fuel combustion low completeness can cause the burner unstable operation in the form of the unsteady pre-blowout burning combined with the pressure oscillations in the burner. At present, methods for ensuring the increase in stability and completeness of the fuel combustion are related to the air rate and temperature changes at the inlet. However, the use of these methods can be unwanted because of their causing the decrease in the coefficient of efficiency and in the resource of the ‘hot part’ of the gas-turbine facility.
  Keywords: fuel gas heating-up, fuel combustion completeness, harmful agents emission, experimental facility, torch unit.
10 The Effectiveness of Extended Schedules of Heating Regulation at CHP Plants with Decreasing Normative Design Temperature of the Supply Water
Authors: Suvorov D.M., Tatarinova N.V., Lyskova E.A. Vyatka State University Kirov, Russian Federation
  Abstract: The aim of the work is a computational study of the effectiveness of the extended schedules of heating regulation at steam turbine CHPPs with a decrease in the normative design temperature of the supply water. The study was carried out on adequate mathematical models of CHP tur-bines and heat supply systems, considering heat pipelines' actual diameters and lengths. The main energy efficiency indicator is the specific reference fuel consumption for electricity sup-ply, calculated under comparable conditions for the operating modes of turbine plants and the load of the heat supply system. The study took into account the electricity consumption for the drive of network pumps, standard heat losses in heating networks and the electricity generation for the heat consumption of CHPPs. The study results allowed for the first time to determine the integral indicators of the energy efficiency of work during the transition of CHPPs from the normative design ones to the temperature schedules reduced by the temperature of the supply water. At the same time, the calculations revealed the limitations on the parameters of the extended schedules of regulation when transitioning to reduced temperature schedules. The most important results of the work should also be attributed to the determination of the optimal schedules of the temperature of the supply water for different values of the district heating coef-ficient of the CHPP. The results obtained are essential for assessing the efficiency of the transi-tion of heat supply systems to reduced supply water's design temperatures when using modern heating regulation schedules.
  Keywords: heat supply system, heating load, heating regulation, temperature schedule, CHPP, specific reference fuel consumption, delivery water.
11 Robust Steganographic Method with Code-Controlled Information Embedding
Authors: Kobozeva A.A. Sokolov A.V Odessа Polytechnic State University, Odessa, Ukraine
  Abstract: In view of the fact that most images are compressed when transmitted through telecommunica-tion systems and telecommunication systems in the energetics, from the point of view of the practical use of steganographic algorithms in real information security systems, such as their property, the ability to effectively resist a compression attack, is of great interest. This work aims at increasing the robustness of steganographic system against compression attacks to ensure the reliability of the steganographic message perception by developing a steganographic method that implements the embedding of additional information in the spatial domain of the container, us-ing the code control of the frequency components that are under perturbations resulting from the steganographic transformation. The goal was achieved using the code control of information embedding: due to preliminary additional coding of the embedded information with codewords for which the Walsh-Hadamard transformants have the specified properties, which leads to a given localization of disturbances in the Walsh-Hadamard domain of the container as a result of the information embedding. The most significant result is the steganographic method developed based on the formed theoretical basis, for which classes of codewords that provide the highest robustness against the compression attacks were constructed. The significance of the results ob-tained is that the developed method ensured a high reliability level of perception the ste-ganographic messages, significant robustness against the compression attacks, as well as sim-plicity of algorithmic implementation and high performance.
  Keywords: steganography, Walsh-Hadamard transform, code control, compression attack, JPEG.
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