The article deals with the development of the method of passive non-parametric identification of a mathematical model of distributed generation (DG) plant based on experimental data in order to determine the optimal tuning factors for generator controllers operating in various modes. The purpose is achieved through the application of the following methods of digital signal processing: wavelet transform for controller noise identification, discrete fast Fourier transform for obtaining the spectral characteristics of the system and weight windows for smoothing the empirical estimates of complex transfer coefficients. To analyze experimental model consistency, the spectrum function of the squared coherence is used. The average random quadratic error in the determination of the complex transfer coefficient modulus has been calculated on its basis. It is also applied the simulation of electric power systems (EPS) with adjustable DG plants in the MATLAB software environment using Simulink, SimPowerSystems software packages and a specialized software package for calculating optimal controller coefficients based on a genetic algorithm. Computer simulation results show that the developed method of passive non-parametric identification of the DG plant model and the software algorithm created on its basis allow to obtain a reliable mathematical model, which can be used for determining the optimal tuning factors for synchronous generator controllers and estimation of the stability margin. The conducted research and computer modeling allowed to derive a conclusion that the presented identification algorithm for the mathematical model of the closed-loop adjustable DG plant allows to determine the optimal setting of synchronous generator controllers, which improves the damping properties of the system making the frequency and voltage control faster and smoother.

The purpose of the work is application of median filtering for increasing the accuracy of power system state estimation (SE) under cyber-attacks. Median filtering (MF) is a nonlinear signal processing technique widely used in digital image processing. Median filtering is performed by letting a window move over the points of a sequence and replacing the value at the window center with the median of the original values within the window. The advantage of the proposed method is the ability of median filtering to discard the values with low accuracy, thus avoiding their impact on general state estimation of power systems. It should be mentioned that the method is easy to implement. MF advantage foundation was performed by modeling of an electrical grid section in the software package PSCAD. The measurements of currents and voltages at each node of the power system were simulated using phasor measurement units. State estimation was performed on the basis of the obtained measurements by the weighted least-squares method with additional one-dimensional and two-dimensional median filtering. The results of state estimation by the specified methods have shown inefficiency of the weighed least-squares method under cyber-attacks on communication channels, since one rough error in the measurement array “spoils” the overall state estimation results, whereas median filtering provides high accuracy. Unlike the weighed least-squares method used for state estimation the proposed method of median filtering allows to reduce the impact of cyber-attacks on the power system. Thus, median filtering is considered to be a promising tool for solving state estimation tasks, the use of which will lead to higher reliability of electrical grids in case of cyber-attacks.

The purpose of the paper is to consider the problem of decision-making on location of a thermal power plant. Traditionally, the problem of choosing the location of any power station consists of two main stages - location selection and a station capacity option. The first stage is the most difficult due to such factors as multi-criteria, high degree of information uncertainty, weak structuring. The need for anticipatory decision-making on further aspects of the problem including site selection and station capacity particularly complicates the location choice. To determine the best location of the power plant a multi-attribute problem is formulated distinguishing two levels of alternatives - location points and power plant implementation options. Due to the fact that analysis conditions of alternatives of two levels differ, it is proposed to apply two methods of multi-attribute analysis. A methodology of two-level multi-attribute analysis of alternatives that uses the method of multi-attribute utility theory and hierarchy analysis is proposed. An example of choosing a location for a thermal power plant in the area with decentralized power supply is given. Towards this end in view, the criteria of the selection problem are defined at two levels of analysis. Attention is also paid to the application of the method of multi-attribute utility theory for the case of determining the single-criterion value function of a non-monotonic type in terms of searching for the “optimal” capacity of a thermal power plant.

The purpose of the article is to reveal the major problems of existing diesel power plant conversion to other types of fuel, which are less costly and more affordable. Diesel power plants traditionally operating on diesel fuel are used to provide electric energy for isolated remote areas of the Far North. Diesel fuel is brought to these areas from afar and is quite expensive, the price of electricity produced by diesel power plants ranges from 10 to 20 rubles/kWh. In connection with the development of oil and natural gas fields in the Far North of Russia, it is advisable to switch local diesel power plants to alternative types of fuels. The study uses official statistics and comparative analysis methods. The current state of the existing diesel power plants is described and the examples of diesel power plant conversion to alternative fuels such as natural gas, oil, fuel oil are given. It is shown that diesel is not the main fuel for power plants. The main problems of diesel power plant switch to other types of fuel are presented. One of the ways to implement the energy-saving policy is the gradual transfer of existing diesel power plants to alternative fuels, which are economically and technically more feasible in certain conditions of the remote territories of the Far North.

The article presents a standard electric power circuit of an AC locomotive of Ermak series operating in the mode of regenerative braking and reveals the circuit’s drawbacks. To eliminate them, it is proposed to use an improved power circuit where standard reversible converter is replaced with a more advanced IGBT-based counterpart and exclude ballast resistor blocks from the armature circuits of traction motors. A mathematical modeling of a standard system of AC locomotive regenerative braking is performed. The conducted mathematical modeling allowed to obtain the curves of the catenary current and voltage, generator current, inverter voltage and power factor. A method of regenerative braking without the application of ballast resistor blocks is proposed. Having analyzed the electromagnetic processes of AC locomotive standard power circuit operation in the regenerative braking mode, the authors have revealed a number of drawbacks that have an adverse effect on the efficiency of regenerative braking. A technical solution for improving the AC locomotive power circuit is introduced that enables a substantial increase of the locomotive energy performance in this operation mode.

The article analyzes the stress-strain state of the cylinder of the low-speed stage of the long-stroke reciprocating piston compressor and pump unit under loading by internal pressure considering the temperature of its walls. The analysis is given to the nature of the working process of both units with regard to their operation features. The relevance of determining the clearances in the long-stroke units is confirmed, since the gaps that emerge in this case significantly affect unit operation and efficiency as a whole. Comparative analysis has showed the temperature effect to be the main cause of the deformed state of these units when in operation. Conducted calculations provide the possibility for optimal development of the designs of piston stages under conditions of temperature loads taking into account the real clearances in the cylinder-piston seal that occur in the deformed state.

Bstract: The purpose of the article is to develop a dimension range of single-phase modules based on experimental data (experimental product tests) for the construction of various layout solutions of industrial furnaces of different productivity. The study is based on the use of experimental data obtained using the test method of the experimental product. The data serve as the basis for the first dimension size module type designs. Conducted researches and experimental data obtained earlier allowed to work out a dimension range of single-phase modules with a mechanical hearth platform as basic elements for designing of industrial firing furnaces of various productivity. Three standard sizes of single modules with a mechanical hearth platform have been developed for the creation of industrial furnaces of various layout solutions of vertical, horizontal or "leaf" type.

The purpose of the paper is to consider the features of dynamic properties associated with the formation of the shaker working element vibration field under different conditions of external dynamic loading as well as to develop a method of dynamic synthesis of mechanical oscillations of the system that provides a given distribution of the oscillation amplitude of the working element points. The study uses the methods of structural mathematical modeling based on the application of the analytical apparatus of the theory of automatic control. Analytic relationships have been obtained that allow the determination of boundary implementation conditions for necessary modes. The technologies for constructing mathematical models for tuning processes of working elements are proposed considering the features and mutual influence under the action of several dynamic factors. The authors propose the use of lever ties created by the operation of various mechanisms in the structure of vibration tables.

The purpose of the paper is to develop a mathematical model of the controller of the axial piston pump Hitachi HPV102GW-RH23A to determine the influence of controller parameters on pump output characteristics and carry out the mathematical modeling of controller operation. The mathematical model of the controller is developed. Its solution scheme in Matlab-Simulink is proposed. Displacements of the spool (x₁), servo piston (x₃) are determined as well as changes in the pressure from a large area of the servo piston (p₃) in time at a nominal pressure in the system and when p>p_nom. The dependence of the servo piston displacement (x₃) on the spool spring stiffness is obtained. The developed mathematical model of the controller allows to find out the causes of malfunctions in the operation of the adjustable axial piston pump. Thus, an increase in the stiffness of the spool 1 spring by 5000 N/m decreases the servo piston displacement and, consequently, the pump flow by 20%. This reduces the load of the basic machine engine and causes the loss of excavator performance as a whole. The increase in the total stiffness of the springs of spool 6 in comparison with the nameplate data can lead to an overload of the excavator engine up to its complete stop.

The purpose of the work is to choose the most rational coating for the specified operating conditions of the metal-cutting tool. The rationality is estimated by the operation time until the rear surface wear becomes less than 0.5 mm. The study is given to the influence of coatings on wear resistance of carbide replaceable inserts of turning cutters at the external machining of billets made of stainless specialized hard-working steel of grade 09Х17Н7Ю. The application field of this steel has expanded considerably, while the recommendations for its machining are outdated. As a benchmark for rationality calculation is taken the operation time of domestic carbide plates made of VK8 grade alloy. Consideration is given only to square replaceable carbide inserts with a central base hole, the side length of a square is 12.7 mm. The need for the study is determined by the fact that available recommendations on the processing modes and choice of tool material for this treatment of the specified stainless steel are physically outdated (there are no machines of those models and tool materials). New recommendations are required for modern conditions. An experimental method is used to study the performance of various tool materials (VK8 substrate + a particular coating) by estimating the increase in the amount of tool wear on the rear surface over the time. For the specified operating conditions, a reserve has been created to form a database for the selection of cutting modes and tool materials. The influence of the choice of coating on the increase in tool wear resistance is shown. As a result, the preferred coatings that allow to conduct a lasting processing without cutting edge replacement have been identified. It is determined that the considered tool materials are substantially unequal by their wear resistance. The preferred tool material is VK8 + Ti(up to 1 µm) + TiN(1 µm) + (NbZrTiAl)N(2.5 µm) in which the coating layers are applied by condensation by ion bombardment with droplet filtration and assisting accelerated ions.

Having analyzed the advantages and disadvantages of modern vane internal combustion engines, the latter have been upgraded. The concept of chain chemical reactions is defined. The historical reference is given on the development of internal combustion engines. The results of analytical studies of the effect of combustion chamber parameters on internal combustion engine indicator characteristics are presented. The upgraded vane internal combustion engine has been patented. The combustion process in the named engine is optimized with the use of analytical analysis methods. Technical indicators of piston and vane internal combustion engines are compared on the basis of literature review. The results of analytical studies show that the upgraded vane internal combustion engines feature the increased power and economic indicating performances. It is found out that technical parameters of the upgraded vane internal combustion engines are higher as compared with the existing vane internal combustion engines. The design of the upgraded engines is characterized by patent purity, which allows for the feasibility of their practical application.

The study is given to the operation modes of a long stroke electromagnetic two-coil hammer with increased striker velocity and impact energy. Theoretical studies involve the use of the methods of field theory and mathematical apparatus of the systems of linear and nonlinear differential equations. Experimental studies are carried out by modeling methods and field tests. The mathematical model of the long stroke hammer is obtained using experimentally obtained static characteristics of the flux linkage and the thrust force for each of the windings. The oscillograms of winding current, striker velocity and travel are obtained. The amount of the energy consumed from the network, power losses in copper, impact energy and hammer efficiency in one operation cycle are determined. A long stroke operation mode of a conventional hammer can be used to improve its operation efficiency. In this case, the values of the impact energy and efficiency of the long stroke hammer significantly increase, whereas the impact frequency decreases and the heating of the machine practically does not change.

The paper analytically justifies and experimentally proves the efficiency and manufacture ease of seamless ring joint with friction of the multilayer cylinder shells for pressure vessels and reactors. The study uses the analytical methods of the theory of elasticity of deformable shells, as well as multilayer and monolithic cylindrical bodies. A method is proposed for determining the sufficient width of the joint of two multilayer cylinder shells to ensure joint efficiency and manufacture ease. A mathematical model is obtained to estimate the parameters of its strength condition. It is shown that the calculated friction coefficient totally depends on the winding density of adjacent (joined) multilayer cylindrical elements. The designed method is tested on the industrial high-pressure vessel, as a result, the condition of ring strength has been obtained. The obvious advantage of a ring joint with friction over welding ring joints is determined.

The purpose of the paper is to consider the use of obsolete metal-cutting equipment upgrading for modern technological tasks as one of the economically viable options alternative to the purchase of new expensive equipment. The use of aggregation when modernizing allows to create technological equipment for a specific group of products while implementing the optimal technological process. Simultaneous tooling of the machine with a modern control system, units and equipment for CAM-technologies and HSM-technologies allows to obtain some qualitatively new equipment. The article demonstrates the practical experience in the modernization of the longitudinal milling machine 6М610Ф11-23 for casting equipment treatment. A description is given to deep modernization involving complete replacement of all drives, electrical and control systems. A technological tooling allowing one machine-tool to produce several products by the optimal technology has been developed and adapted. This is the guarantee of high quality and performance. The elimination of additional re-installments has significantly improved the machining accuracy. The use of modernization provides an economically viable alternative for organizing a modern high technology production on the basis of available equipment.

The purpose of the article is to study the processes of boron, titanium and aluminum electrodeposition on carbon graphite cathodes, identify the possible ways to overcome the existing restrictions on the use of solid cathodes for cryolite-alumina melt electrolysis. X-ray diffraction analysis (XRD) was carried out using Shimadzu XRD-6000 automated x-ray diffractometric equipment (CuK_α radiation, graphite monochromator). The microstructure of the sample surface was examined with the use of the JEOL JSM 7001F scanning electron microscope (Japan). X-ray microanalysis and energy dispersive microanalysis (SEM-EDS analysis) as well as EDS-mapping were performed using the Oxford Instruments energy dispersive spectrometer (UK). The results of the electrochemical synthesis of titanium diboride TiB₂ at the temperature of ~ 975°C and current density of 0.82 A/cm² with the subsequent deposition of aluminum on the carbon cathode and surface study by electron microscopy suggested the causes of the unstable electrolysis and poor quality of coatings. These causes can include chemical heterogeneity and physical microdefects of the surface, which initiate the concentration of current on the micro-sites of defects with simultaneous increase in the electrolysis rate. The subsequent shortage of electroactive ions in the cathode space approximates and then reaches the current density above the limiting diffusion one successively for the discharge of boron, titanium and aluminum with a subsequent increase in voltage to background decomposition potentials (cryolite, sodium and aluminum fluoride). These processes result in the interaction of intrinsic and impurity aggressive elements with the surface material, the progressive development of physical micro-defects as well as cathode passivation with refractory sediments and electrolyte components. Ultimately, the normal process of electrolysis is disrupted and followed by the need to stop. One of the reasons for the lack of progress in the development of electrolysis technology with the use of inert electrodes lies in the specific electrochemical processes on the solid surface of polycrystalline cathodes. The established causal-and-effect relationship between the heterogeneity of the electrode surface, the instability of the process of electrolysis and cathode passivation makes it possible to determine the application conditions of solid cathodes. To solve these problems, it is proposed to use the technologies of composite cathode boronation and low-temperature synthesis of titanium diboride developed in laboratory conditions.

The purpose of this work is to form specific approaches and directions in the field of producing zinc powders with desired properties from alkaline electrolytes. The analysis is given to the research results of many authors (86 sources) on the influence of various conditions of zinc powder electroextraction from alkaline electrolytes. Still there is no comprehensive theoretical explanation of the mechanism of powder formation in zinc electrolysis from alkaline solutions. Despite the multiplicity and diversity of published data, it is impossible to determine the production conditions of zinc powders with desired properties from zinc electrolytes without carrying on one’s own systematic studies. Consideration is given to the research methods of zinc electrodeposition in the solutions of sodium hydroxide on the stainless steel cathode using cyclic volmperometry, chronoamperometry and chronopotentiometry. In the conditions of laboratory electrolysis the influence of electrolyte composition, impurity concentration, current density, temperature, introduction of additives on the current output and morphology of the obtained powders is studied. It has been revealed that there is no consensus on the impact of electrolysis conditions in terms of current efficiency and power consumption among the authors. It is found out that the advantages of the electrolysis of alkaline zincate solutions are: high purity of the resulting metal, possibility of obtaining the powders of the specified size, good compressibility and sintering, possibility of using non-acid-resistant structural materials.

The purpose of the paper is study of the behaviour of bauxite concentrate produced by the thermochemistry-Bayer method at the stage of pressure leaching; investigation of the effect of calcium oxide dosage supplied for bauxite concentrate pressure leaching in the Bayer process; determination of calcium oxide optimal dosage; development of methods to control bauxite concentrate opening using the chemical analysis of solid and liquid phases; production of thermoactivated product due to the roasting of initial bauxite at 1000 °C and its desiliconization with alkaline solutions, followed by bauxite concentrate leaching according to the Bayer method in autoclave conditions; complete silicate analysis of the solid phase (red mud) and determination of the content of general, caustic, carbonate alkali as well as Al₂O₃ and SiO₂ in the liquid phase. Thermal activation of bauxite allowed to obtain a product with a silicon module (μ_Si) that equals 11.6 from high-silica bauxite from one of the Russian deposits. The effect of CaO dosage on the opening of bauxite concentrate has been studied. The conducted analysis of solid and liquid phases has showed the possibility to determine bauxite concentrate opening at pressure leaching. The optimal dosage of calcium oxide has been determined. The conducted laboratory studies made it possible to find out that the firing temperature (1000 °C) followed by 1 hour exposure on the one hand ensures the obtaining of high-quality concentrate, and on the other, allows to achieve theoretically possible alumina extraction under further traditional hydrometallurgical processing. It has been estimated that the optimal dosage of calcium oxide for this type of bauxite concentrate is 2.5% of the concentrate weight. The chemical analysis of pressure leaching products has showed the possibility to determine alumina extraction from bauxite concentrate in the aluminate solution (by the composition of both solid and liquid phases). A methodology of rapid analysis based on the composition of the liquid phase has been developed. It enables determination of the production possibility of the bauxite concentrate with a high silicon module as well as estimate its opening at the leaching stage in the Bayer process.

The purpose of the paper is to study the effect of flocculants on the kinetics of thickening and washing processes of red muds obtained from low silicon bauxites in the production of alumina. To study the kinetics of red mud slurry thickening the method of controlling the pulp level during the settling process is used. The method of decants with decreasing concentrations is applied in the study of decanting countercurrent washing. The flocculant solutions are prepared according to a certain method, which allows to obtain working solutions of flocculants that have the maximum effect on red mud slurry clarification (high clarification rate, low content of dispersed particles in the drain). The effect of flocculants on the thickening and washing kinetics of red muds obtained from low silicon bauxites is studied. It has been determined that flocculants influence the formation of thickening zones. It is noticed that, the isoelectric state is equally observed for both pulps treated and non-treated with reagents at a certain concentration of alkaline aluminate or alkaline solution corresponding to the maximum clarification rate (maximum productivity of the thickener and thickener-washer). The use of flocculants at the stage of thickening ensures the subsequent increase in the performance of washers in washing stages. The maximum performance is demonstrated by the washer where the concentration of the dissolved valuable substance corresponds or is close to the concentration of the isoelectric state. In this case, the thickener-washer provides a clarified solution with a minimum content of dispersed particles. It has been found out that the use of flocculants influences the formation and the length of the main thickening zones. Under statistical conditions of flocculated pulp deposition, a decrease in the clarified zone depth is observed whereas the transition zone is significantly developed. A similar effect of flocculants has been noted for all stages of countercurrent decantating washing of red mud in the conditions when the concentration of the dissolved valuable substance (aluminate solution) decreases from the first to the last stage of washing.

The purpose of the paper is to аssess the prospects for using the Molokovskoye deposit (Transbaikalia) clay in metallurgical practice. The mechanical strength of bonding chamotte blocks with clay and chamotte crumb pastes is determined. The results obtained indicate the analogy of adhesive interactions ensured by the proximity of the crystal chemical composition. Despite the fact that, in addition to aluminum and silicon oxides, the Molokovskoye deposit clay contains up to 20% of oxides of other elements, their participation in building the interlayer structure does not lead to a noticeable decrease in strength characteristics. The properties of pastes made of clay and chamotte crumbs are studied using traditional physicochemical and thermal engineering research methods including gravimetry, chemical analysis of an oriented sample of mineral raw materials. Extensometering on the Shimadzu Autograph AGS-X testing machine is used to determine the mechanical strength. The chemical and mineral composition of the Molokovskoye deposit clay is determined. It is shown that about 80% of the total composition is formed by aluminum oxide (18%) and silicon oxide (61%). The clay also features the presence of oxides of sodium and potassium, calcium, titanium, iron, magnesium and manganese. Mineral manifestations are found in the form of calcite, alkaline feldspar, muscovite, smectite and mica-smectite. The conducted laboratory studies classified the clay from the Molokovskoye deposit (Transbaikalia) able to be used in metallurgical practice and useful to be recommended for lining masses, coating and fixing of blast-furnace masonry, processing of auxiliary tools such as molds, samplers and spoons for melt.