The purpose of the paper is to automate the most complex and time-consuming calculations when designing turbogenerators with any number of poles and various cooling systems as well as to reduce the calculation time and improve calculation accuracy. The rapid growth of the energy sector in Russia and in the developed countries of the world is ensured by the construction of thermal and nuclear power plants equipped with modern powerful turbine generators, which are complex electric machines manufactured with the use of the latest achievements of science and technology. Therefore, scientists and specialists are developing and looking for the new methods and solutions in order to improve the characteristics and designs of turbogenerators. This paper presents the methodology, algorithms and developed programs that allow automated performance of the most complex and time-consuming calculations when designing turbogenerators with any number of poles, with indirect and direct cooling of all types of turbogenerators used in thermal and nuclear power plants. The electromagnetic calculation algorithm involves the calculation of the magnetic circuit of a turbogenerator for a pair of poles with the use of modern grades of steel for stator and rotor magnetic circuit manufacture. The calculations are performed using the Microsoft Excel program. The advantage of this methodology, algorithms and program are as follows: automation of calculations, automatic construction of graphs of idling and efficiency characteristics, convenient and intuitive interface that designers can use without any difficulty.

The purpose of the paper is to present an improved method of active power equalization on the secondary windings of the Scott traction transformer in the power supply systems of AC railways located in the proximity to the facilities of the agroindustrial complex, gas supply systems, etc. Active power distribution using automatically controlled thyristor bridges with pulse width modulation and capacitive storage devices allows to reduce the asymmetry and unsinusoidality of currents and voltages in the primary three-phase network almost to zero at suddenly appearing and disappearing mobile traction loads, such as high-speed electric trains. To control the currents and voltages in the windings, digital filtering algorithms have been applied, which form the required number of voltage levels at a given frequency of pulse width modulation. The efficiency of these algorithms is confirmed by computer simulation in the Matlab environment. It is proposed to improve the method of power equalization on the secondary windings of the Scott traction transformer with the use of digital filtering-based automatic control algorithms. The power equalization device together with the Scott transformer ensure high quality of electric energy in the primary three-phase network in terms of asymmetry and unsinusoidality of currents and voltages, due to which electromagnetic compatibility of the traction power supply system and the power supply system of various agricultural facilities, oil and gas complex, and others located in the proximity of railways is provided.

The purpose of the article is to show that the measuring circuit in the form of a measuring bridge powered by a high-frequency generator is most suitable for electric machine diagnostic system implementation. Rotating electric machines are widely used for electrical energy production in electric power industry, and as drives of various types of mechanisms. One of their most common damage is the static eccentricity of the rotor arising either due to bearings destruction or to the displacement of risers where the bearings are installed. It is a usual practice to detect the given type of damage using eccentricity diagnosing systems, in which the currents and electromotive force in the windings are used as information about the damage (despite the undoubted benefits of these devices they don’t have wide distribution). It is caused by the fact that a simple diagnostic system reliably detecting (irrespective of the fluctuations of the parameters of the supply main and load) the presence and displacement value of the rotor shaft is still not developed. These shortcomings can be overcome through the use of the diagnostic system, in which the rotor displacement is controlled by a capacitive measuring converter and the corresponding measuring circuit. The analysis of the design features of electric machines has shown that it is advisable to make a measuring converter a device, one of the electrodes of which is the surface of the shaft or the rotor core, and the other - the electrode in the groove wedge or a special insulated housing. It is found out that the implementation of the diagnostic system with the measuring converters is possible only when using a measuring circuit built on the principle of a voltage divider, a resonator cavity, a capacitive-type circuit or a measuring bridge. Further selection of the measuring circuit and its location in the machine is carried out on the basis of the measuring converter design and the interference protection method. It is determined that a measuring circuit in the form of a measuring bridge powered by a high-frequency generator where the measured signal is a filter with the same frequency is the most suitable for diagnostic system implementation. The final choice of the measuring circuit diagram for further preferred consideration and development of electric machine rotor eccentricity diagnosis is based on its usability, measurement accuracy and sensitivity.

The purpose of this article is to consider the problem of decision-making on the location of a thermal power plant in an area with decentralized power supply. The task of choosing the location of any power plant traditionally consists of two main stages - selection of the power plant location and the construction site. The last stage involves the specification of the plant capacity. The first stage is the most difficult due to such factors as multi-criteria, a high degree of ambiguity of information, weak structuring. In particular, the location selection is complicated by the need for preliminary decision-making on further aspects of the problem including site selection and plant capacity. To determine the best location of the power plant a multi-criteria task is formulated with the allocation of two levels of alternatives - locations and implementation options of the power plant. As the analysis conditions differ on each of the levels it is proposed to use two methods of the multicriteria analysis. The methods of two-level multicriteria analysis of alternatives developed with the participation of the author involves the use of two methods of the multicriteria analysis. These are finding of the multicriteria utility and hierarchy analysis. The latter is easy to use and has a wide practical approbation on real decision-making problems but its application involves a "one-time", a priori mental structuring of preferences of the decision-maker in relation to alternatives and evaluation criteria. In cases when the decision-maker believes that the best strategy for solving the problem of multicriteria choice would be the gradual selection of non-dominant alternatives and elimination of dominant ones, the method of hierarchy analysis should be replaced. This article focuses on the ELECTRE I method used at the second level of analysis - it is the first method of the ELECTRE threshold method family. The article provides an example of choosing the location of a thermal power plant in the area with decentralized power supply. To this end, the objectives and criteria of the selection task are defined at two levels of analysis. The criteria characterizing the objectives are described as well as each location point of the thermal power plant. Further, the analysis is carried out using MAUT and ELECTRE I methods. In conclusion, the results are discussed, the effect of individual factors on the comparison result is considered.

The purpose of the article is to develop a methodology for planning long-term regimes of the Angara-Yenisei cascade of hydroelectric power plants providing the maximum effect from the use of electric energy in the electric power system and minimal risks of violating requirements of other water users. Consideration is given to the stochastic optimization with the use of the calculation method of HPP water-energy mode and calculation of the steady-state mode of electric networks. The planning methodology of long-term water and energy regimes of a hydroelectric power station and an optimization model minimizing the target function consisting of risks of violation of various water user requirements and deviation of the economic effect from the maximum values are developed. The HPP operation modes are calculated for tributaries of various supply, the obtained results are analyzed. The performed calculations of the optimal operation modes of the hydroelectric power plant prove the effectiveness of the methodology and the optimization model.

The purpose of the paper is using the simplest scheme to show the negative effect of the wrong choice of inverter control laws on the dynamic stability of the electric power system with connected electronic generation. Today the small-scale generation based on renewable energy sources is becoming more and more widespread. In the majority of cases, it is non-synchronous. As distribution electrical networks combining synchronous and non-synchronous generation have a synchronous basis the small-scale generation using renewable energy sources is connected to the distribution network through an inverter. This type of generation is called electronic. To ensure the dynamic electro-mechanical compatibility of electronic generation and the external electrical system it is proposed to form the invertor control laws on the basis of a reference model, the electromechanical parameters of which are consistent with the data of the external network. The identification method of electromechanical parameters of the external power system is proposed for reference model adjustment. The results of method approbation on the example of a real 0.4 kV electric network based on the transient histogram results are presented.

The purpose of the paper is to indicate the importance of measures on diagnosis and maintenance of solar panel bypass diodes. The study involves the theoretical analysis of information data on bypass diodes and their troubleshooting. Consideration is given to solar panel defects arising from faulty bypass diodes. The study uses computer simulation in PVSYST program, simulates bypass diode faults on YL-250P-29b solar panel and performs bypass diode diagnostic by the methods of short-circuit current analysis at partial shading and idle voltage parameter under normal conditions. It is determined that the methods of thermal imaging diagnostics (including those using a drone) and visual inspection are not accurate troubleshooting tools for faulty bypass diodes. The analysis methods of short-circuit current at partial shading and the idle voltage parameter under normal conditions are applicable for small solar power plants. They also can be used for the diagnosis of bypass diodes of solar cell arrays assembled from spare parts as well as for tools and devices at large solar power plants. The method of thermal imaging diagnostics using an external source is recommended to use for full fault diagnosis of bypass diode breaks in large solar power plants.

The purpose of the paper is experimental determination of the dependence of coverage degree at shot peen forming on processing modes. Shot peening is a promising direction in the field of shaping long panels and skins. This method allows to achieve high accuracy of received contours along with the increased efficiency of the process and implemented strengthening effect that improves the fatigue strength and durability of parts. The required accuracy of the shape is achieved in shot peening with the use of an incomplete coverage degree of the processed surface by shot indents, which indicates the efficiency of the production process. The question of the need for the prediction of the dependence of the achieved coverage degree is important when selecting the processing mode. The method of planning a factorial experiment and calculating the coverage degree based on the measurement of shot indent depths using the three-dimensional optical scanning is applied. The actual dependences of the coverage degree on shot peening modes at shot peen forming are obtained.

The purpose of the article is to study the vibration characteristics of the windings of NB-514 pulsed current traction motor to identify the causes of early failure of the pole windings in order to improve their reliability in operation. The amplitude-frequency characteristics of NB-514 pulsed current traction motor winding vibration are studied; the analog vibration signal is converted into a digital code, which follows by the signal processing by digital methods. To study vibration characteristics a test bench is created, which enables the measurement of amplitude and frequency characteristics of traction motor vibrations. The analysis of the obtained measurements has shown that there are electromechanical resonances with a high degree of q-factor of the compensating winding of NB-514 traction motor and connection points of its windings and the brush holder bus at the frequencies close to 100, 200, 400, 500 and 600 Hz.

The purpose of the present research is to develop a software package that allows to analyze the effect of turbomachine impellers oscillation detuning on their vibration frequencies and durability. The software package described in the article allows to analyze the frequencies of natural and forced oscillations, as well as the durability of gas turbine engine and other turbomachine impellers with parameter mistuning. The article presents the main provisions of the finite element method used in the analysis of oscillations and durability of gas turbine engine rotor elements (the algorithm for calculating their impeller durability is given). The software package is tested on test models. The comparison of test model calculation results and the results obtained in the ANSYS software package demonstrate a sufficiently small error that allows to use the developed software package to solve the analysis problems of the effect of turbomachine impellers oscillation parameter detuning on their vibrations and durability. In addition to the test models, the durability of a real impeller with Rolls-Royce integrated blades is calculated. The article shows the analysis results of the effect of parameter detuning introduced by material stiffness variation in different parts of the blades on blade durability. At the same time, the study is given to the several variants of blades with different values of Young's modulus for different parts of the blade and their combinations. Blade durability is calculated using different hypotheses of damage accumulation (Serensen, Corten - Dolan, Palmgren - Miner). The calculation results have led to a conclusion that even a small detuning can have a noticeable impact on impeller durability.

The purpose of the article is to create a database on cutting forces P_z, P_y to enable the simulation of loads on the tools made of R9M4K8 and X12 steels and on machine-tool parts and components using computer programs. forces additionally allow to simulate thermal phenomena in the grinding zone, which being an adverse factor in abrasive processing reduce the performance of cutting tools and dies. The cutting forces are measured using the Kistler dynamometer system and the output of the obtained information is presented in the computer. Correction factors to the basic model taking into account the idle passes by the width of the processed surface are obtained. It is found out that the increase in the operational allowance when grinding with cubic boron nitride wheels is not accompanied by an increase in cutting forces, which is typical for traditional abrasive wheels (in particular for electrocorundum). The cutting forces at grinding of die steel X12 are greater than those at grinding high-speed steel R9M4K8: P_y - by 1.2 times, P_z - by 1.36 times. The results obtained will increase the efficiency of using CAE-systems (Computer-aided engineering systems) in mechanical engineering, particularly in grinding. It is confirmed that the increase in the grinding coefficient K_gr=P_z/P_y reflects the improvement in the abrasive wheel operating conditions. In particular, it increases when the wheel comes out of contact with the workpiece from 0.32 to 0.46 at the reverse motion in the same zone from 0.46 to 0.64.

The purpose of the article is to develop a method for determining the optimal machining modes of milling machines by estimating the vibration level and initial contact of a cutter tooth and a workpiece. The work is based on the use of experimental data obtained by measuring vibration characteristics, which serve the basis for determining the optimal milling modes of the end mill with a hexagonal plate. The experiment results in the development of a methodology for determining optimal milling modes (based on the obtained experimental data of the vibration level), and identification of the relationship between the initial contact line of the cutter tooth and the workpiece by means of a 3D model. The methodology of determining the optimal milling modes is developed on the basis of the experimental data of the vibration level. Based on the results of the conducted studies, the recommendations are given on setting the optimal processing modes for a cutter with a hexagonal plate taking into account the comparison of the obtained RMS values of the vibration velocity and General technical standards of permissible values of the overall vibration level. The relationship is revealed between the line of initial contact of the cutter tooth and the workpiece by means of a 3D model and the level of vibration.

The purpose of the article is to study the formation of performance properties and quality parameters of the surface layer of 3KH2V8F (3Х2В8Ф) die steel used in manufacturing of tooling for hot bending of titanium shields by technologically sequential operations including high-temperature diffusion boroaluminizing and final machining. The methods of optical microscopy and X-ray phase analysis are used to determine the structural-phase state. Studies are conducted to determine the roughness and microhardness of the surface layer. Boroaluminizing at a temperature of more than 1050°C results in the formation of diffusion layers with a composite structure on the steel surface. After processing at 950°C a diffusion layer with a layered structure is formed. It is found that the surface roughness after the boroaluminizing at 950°C increases up to Ra 4 µm while processing at the temperature of 1050°C increases the roughness up to Ra 7.7 µm whereas the initial roughness in both cases is Ra 1.5. Finishing grinding used as final machining decreases roughness from the above values to Ra 0.09 µm and Ra 0.43 µm, respectively. Finishing grinding provides the required surface quality while maintaining the functional properties of the diffusion layer. It should be mentioned that the issues of technological support of performance properties must be considered in a complex.

The purpose of the paper is to show an optimization method of the mechanism of precise positioning of a module (an actuator for automatic production). The design of the module (feed nut assembly) allows to change mechanism parameters including the drive radius in a wide range. Finding the best value of the reduction radius in terms of speed, i.e. reducing the acceleration and braking time, increasing the speed of steady motion and reducing the pause time improves the performance and efficiency of the system as a whole. This task is a priority for development engineers both in designing new equipment and upgrading. L.S. Pontryagin’s maximum principle is used for optimization. Firstly, a telescopic mechanism with a feed nut assembly is calculated and the motor is selected. Then, the mechanism is studied in order to optimize the feed nut assembly parameters in terms of obtaining the maximum efficiency (up to 90%), the minimum acceleration and braking time (selection of the drive reduction radius). It is possible to vary the type of transmission (rolling, sliding, roller-screw), pitch, thread angle and a number of other characteristics. When choosing an electric motor, machines with high overload characteristics - direct current with magnetic excitation, induction with a short-circuited valve rotor - are more preferable. Calculations are performed for a large group of modules of automatic machine-building production taking into account various combinations of actuator parameters including load capacity, operating modes, loading, losses in the motor, and a number of others. The study results are as follows: the optimal gear ratio in the mechanisms depends on the processing mode of the given movement, the type of the movement speed graph is determined by the given restrictions of phase coordinates and the value of the specific movement. It is also determined that in the case when the load changes in a wide range the radius should be chosen according to the nominal value of the load, whereas the installation between the motor and the reducer screw has little effect on the optimal value of the reduction radius. The procedure is recommended to be used at the design stage when searching for an optimal transmission device in the electric drive system of precise positioning of automatic production.

The purpose of the article is to obtain the data necessary for the synthesis of optimal control systems. The successful solution of the problem of creating control systems for tray distillation columns used in various chemical and metallurgical processes requires the construction of mathematical models that allow to carry out the study of objects on modeling facilities. Analytical solutions of control systems that describe the processes in columns involve significant computational difficulties. It seems useful to build structural diagrams as an initial mathematical description of the simulated fractionating distillation columns. The known static and dynamic properties of the tray distillation column are used to separate binary mixtures in the way that enables the construction on their basis mathematical models convenient for the synthesis of automatic control devices. The proposed block diagram is a typeset model of a facility, which serves the basis for obtaining a general solution for specific sizes of its elements (taking into account the nonlinear dependencies in the system under examination). A mathematical description of the fractionation process is given on the basis of the material balance of the more volatile component and consideration of the kinetics of mass transfer on the trays.

The purpose of the article is to study the following topical issues: determination of the development level and current status of the titanium diboride production technology by the method of electrochemical synthesis in molten salts; promotion of the development and designing of the new generation of aluminum electrolyzers with horizontal and vertical arrangement of inert electrodes; large-scale and critical review of the achievements of the world research centers in the development of the technology of electrochemical synthesis of titanium diboride. Resumed in the 1990s interest in obtaining aluminum wetting titanium diboride coatings on the cathode surface by the method of electrodeposition right in the molten salt is still continues. Some progress has been achieved in the laboratory conditions, however, the electrochemical synthesis of titanium diboride does not find any commercial use. This method is being developed as an alternative to the costly manufacturing technology of compact electrodes, the use of which in the development of drained cathode or vertical electrode technology is hindered by the high cost of materials as well as by the technological features of specific cathode processes. Attempts to perform long-term electrolysis using these technologies (electrochemical synthesis and compact inert electrodes) usually result in failed wettability of the cathodes and periodic occurrence of concentration polarization. The latter lead to the instability of electrochemical processes and cathode passivation by impurities and electrolyte components. The main reason for the lack of progress in the development of electrochemical synthesis of titanium diboride and electrolysis technology using solid cathodes (the technology of new generation of electrolyzers with horizontal and vertical arrangement of inert electrodes) is the volume and surface inhomogeneity of polycrystalline cathodes. To solve this problem, it is proposed to use the microboriding technology for carbon titanium-containing surface, individual diboride titanium or composite diboride titanium carbon graphite cathodes produced using the technology of low-temperature synthesis of titanium diboride.

The purpose of the work is to create a mathematical model of furnace thermal operation for control problems, on the basis of which a "virtual twin" of the homogenizing furnace can be implemented. Recently, the heating quality indicators of aluminum semi-finished products and products before further processing are becoming particularly relevant in the processes of aging or hardening also due to the introduction of the international quality standard ISO at metallurgical enterprises. At the same time, the existing control systems of heating furnace parameters mainly regulate the local heater by measuring the air temperature near it. The task of maintaining the desired heating volume of the entire furnace and the charge is quite difficult under this type of control and requires constant adjustment of the proportional-integral-differentiating regulators by an experienced employee. The energy intensity of aluminum processing is also high but not all enterprises are able to replace outdated furnaces. Then the resource-saving opportunities center around the improvement of control systems. In particular, the replacement of traditional response regulation with proactive regulation is a promising direction. Therefore, the development of mathematical models and software enabling to calculate and predict the temperatures of different areas of a furnace and heated materials depending on the change in heating conditions is a relevant task. Modeling and studies are carried out using ordinary differential equations and explicit difference schemes. The paper proposes a dynamic model of heat transfer in a homogenizing furnace and performs test calculations demonstrating the applicability of this model to the selection of heating modes and algorithms. The model can also be used as a basis for the development of a furnace digital twin. The presented models and calculation methods are applicable as developments of modern control systems and heating optimization of not only metal products but any materials.

The purpose of the paper is to establish physico-chemical regularities and technological parameters of molybdenite concentrate thermochemical decomposition with the use of various magnesium minerals (brucite Mg (OH)₂, magnesite MgCO₃) in the oxidizing medium. The compositions and physico-chemical properties of initial materials and interaction products are studied by atomic absorption spectrometry, photocolorimetry, differential scanning calorimetry and x-ray phase analysis. Physical and chemical modeling of the systems MoS₂-MgCO₃-O₂ and MoS₂-Mg(OH)₂-O₂ is carried out by means of the universal program for determining the equilibrium parameters of multicomponent heterogeneous systems "Terra" and the Temkin-Schwarzman method. It is shown that magnesium molybdate (MgMoO₄) formed in the process of interactions is stable within the range of the studied temperatures from 300 K to 1150 K. We have determined the technological parameters of molybdenite concentrate sintering with each of the additives providing directed transformation of the refractory mineral form into the soluble molybdate phase MgMoO₄ and sulfur oxide into non-volatile magnesium sulfate: temperature 600°C, firing duration 60-90 min, consumption of brucite or magnesite is 100-110% of stoichiometrically required for complete binding of molybdenum and sulfur into a cinder. The developed method of molybdenite concentrate thermochemical activation makes it possible to reduce the cost of the thermochemistry process by using magnesium minerals as a raw material additive and promotes the effective interaction of decomposition products with the formation of soluble compounds MgMoO₄ and MgSO₄.