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Various low-power generator sets (GS) are mainly integrated into microgrids by means of inverters coupled with energy storage systems (ESS). ESSs are connected either to the DC busbars of GSs or to the AC busbars of the microgrid, in this case they are equipped with individual inverters. Use of ESS helps balance power in cases of load surge / loadshedding when the microgrid is islanded. This paper overviews approaches to arranging primary and secondary control of the operating parameters of microgrids. It discusses the technical challenges of, and possible solutions for, implementing primary and secondary control in low- and medium-voltage distribution grids featuring inverter-connected GSs. Calculations of electromechanical transients show that inverter-connected GSs have advantages over conventional GSs when used microgrids that are weakly connected to the power system (the external grid) or islanded. In a microgrid featuring inverter-connected GSs, active and reactive power need to be controlled separately as in power systems featuring conventional GSs; implementation of such controls must be adjusted for the parametric and topological characteristics of low- and medium-voltage distribution grids. To address the issues of linked control, this paper proposes a comprehensive approach that adjusts microgrid design for the specifics of inverter-connected GSs, improves inductance, and incorporates algorithmic solutions. It details upon the virtual impedance algorithm, which extends the common principle of droop speed control. Its implementation helps load the GSs and the ESS with adjustments for their installed capacity; it can also simulate the mechanical constant of GS inertia. Primary control has a low margin that mainly comes from the ESS; thus, backups available to secondary control must be used to compensate for the deviations in operating parameters; this is a key challenge of secondary frequency and voltage control in microgrids. When primary and secondary voltage and frequency controls have been duly implemented in a microgrid, its GSs, the ESS, and electricity delivery to the loads within the microgrid can all operate reliably in a variety of operating situations.

Voltage sags and interruptions in the electric power systems (internal grids) of industrial facilities are caused by various short circuits, including those that occur in external grids. If the depth and duration of such sags and interruptions exceed the rated limits for critical loads, they cause continuous processes to shut down, which produces defective products and entails substantial losses. Russian standards and regulations do not set forth requirements with respect to voltage sags and interruptions, which means that industrial companies cannot sue grid operators for damages. This is why dynamic voltage stability of critical loads involved in continuous processes has to be addressed within the internal grid. They analyze the effectiveness of solutions designed for dynamic voltage stability of critical loads; these can be shared, used on a single site or designed to power secondary circuits. It shows that use of dynamic voltage restorers (DVR) and dynamic voltage sag correctors (DVSC) can be a cost- effective solution if the topology and specifications are configured appropriately. The paper presents general technical requirements for sag and interruption compensators, which are adjusted for cost-effectiveness. Case-specific feasibility testing should be based on daily readings of electrical parameters and electric power quality readings, calculated electromechanical transients, and a feasibility study. Use of DVRs at an industrial facility helped stabilize the voltage curve and reduce the span of irregular voltage fluctuations by a factor of 3, reduce the average voltage at the 6 kV busbars without compromising equipment performance, and improve the starting conditions for AM clusters and self-starting conditions for large AMs. Thus, lowering the elevated voltage at the 6 kV busbars helped cut electricity purchase costs. In most cases where accidents cause disturbances in the external 110 kV grid, DVRs coupled with the automatic voltage controls of power transformers were able to prevent process shutdowns, which constituted the key cost effect.

The pandemic of the coronavirus infection COVID-19, which began at the end of 2019 and caused by the SARS-CoV-2 virus, has led to unprecedented consequences in the world. By the end of May 2021, in the world there were 167 million infected and 3.5 million died directly from infection [1]. SARS-CoV-2 is a beta coronavirus, so it shares many conserved fragments with other known viruses of this type [2]. Since the beginning of the spread of the COVID-19, one of the important issues of research of the SARS-CoV-2 virus has been the search for its conserved RNA motifs and their functional annotation. These motifs are potential targets for the treatment and diagnosis of a disease caused by the virus. This report examines the structural RNA fragments of SARS-CoV-2, similar to the corresponding fragments in other beta coronaviruses [2]. For these RNA motifs the nucleotide variability during the spread of the virus, depending on their secondary structure, was investigated. All the motifs display the similar background variability although contain hypervariable positions.

In the paper results for modelling a characteristic pattern of the solar wind flow and its turbulent structure are presented. We use a gravitational magnetic hydrodynamic model, and for the model we have created an effective numerical method based on Godunov’s method and piecewise parabolic reconstruction of the solution. We consider the evolution of the MHD turbulence of the supersonic gas flow, where random strong transversal velocity disturbances are set, the problem is considered in the vertical magnetic field. For the formation of a reference test of the supersonic MHD turbulence evolution a detailed analysis of the flow is carried out.

This work aims at creating a universal software package for the development and testing of triangulation methods using structured lighting for measuring the three-dimensional geometry of objects in difficult ambient lighting conditions. As a result, a software package meeting the stated requirements is created. Lighting is based on the Fong model. A method for preloading objects is implemented to optimize the operation of the software package. An accelerated method for creating shadow maps is proposed and implemented. The developed software package is shown to successfully perform all required functions.

Current work is devoted to the development of a device for monitoring the dynamic shape of a power unit. The work is based on the FMCW method. The light source uses a low-coherence semiconductor laser diode. Signal processing is performed on an adapted Doppler processor. The paper describes the methods, hardware and signal processing algorithms.

This work deals with the development of the software for the system of synchronous control of the optical system of visual control over dynamic objects and the creation of algorithms for resolving conflicts of simultaneous illumination by several light sources. The software for the microcontroller for the system hardware is created as part of the work. An application for remote configuration of the device is developed. Algorithms for time-separation of signals for switching on lighting are implemented.

The hydrodynamic structure of the flow in a flat channel with sudden expansion was studied at constant flow rates of liquid and gas in the vertical flow at Re = 6600 and gas content β = 0.03. The measurements were carried out using the PLIF method; and with this view, fluorescent particles for PIV studies and the dye Rhodamine G were added to distilled water. An optical threshold filter was installed on the lens of the video camera. When processing images to obtain data on the local gas content, only bubbles falling into the plane of the laser beam were considered (the boundary glows, casting a shadow).

The paper analyzes advantages and drawbacks of the radioisotope thermoelectric generators (RTG) based on application of 238Pu and 232U. Currently, the RTG on 238Pu are widely used for long-term autonomous power supply of spaceships due to the following positive properties of 238Pu: high specific heat generation rate, long half-life, weak emission of neutrons and γ-rays. Isotope 238Pu may be produced by neutron irradiation of 237Np (main component of transuranium radioactive wastes) in nuclear reactors. The paper considers application of 232U for the same purpose because of the following positive properties of 232U: power elevation during initial 10 years of the RTG operation (effect of α and β-emitters in 232U decay chain), long half-life (comparable with 238Pu half-life). Unfortunately, 232U decay chain includes also intense emitters of high-energy γ-rays. As a compromise, a possibility is considered to create the RTG based on mixture of 238Pu with small (below 5%) additive of 232U. Such RTG will be able to keep long-term stable operation at high power level. The following two-step technology is proposed to produce 232U: generation of 231Pa in thorium blanket of hybrid thermonuclear reactors and subsequent neutron irradiation of 231Pa in nuclear reactors till accumulation of significant 232U quantities.

The article is devoted to the urgent problem of large-scale production of plutonium-238. Various starting isotopes and Pu-238 production schemes are analyzed. The isotope characteristics of the chain based on the starting Np-237 isotope are presented. It has been substantiated that the region of neutron resonant absorption for the isotope Np-237 is the preferred spectrum of its irradiation. It is proposed to form a region with a preferred neutron spectrum in the fast reactor core for irradiation of neptunium-237. The preferred spectrum is achieved by a heterogeneous target structure including neptunium-237 and a moderator with a high atomic weight (Pb, Pb-208, Bi, Pb-Bi eutectic). It is shown that when a moderator with a high atomic weight is used, it becomes possible to form an extensive region with the preferred spectrum. In conclusion, the main conditions for the large-scale production of isotopically pure Pu-238 in a fast reactor are formulated.

The paper analyzes a possibility to involve hybrid thermonuclear reactors into the existing nuclear power systems. The possibility is related with production of non-traditional nuclear fuel in thorium blanket of hybrid thermonuclear reactors on D-T plasma. Non-traditional peculiarity of such a fuel consists in significant amounts of some non-traditional isotopes, namely231Pa and232U, together with traditional uranium isotope233U in the fuel. High-energy (14.1 MeV) thermonuclear neutrons can provide accumulation of significant231Pa and232U quantities through threshold (n,2n) and (n,3n) reactions. The promising features of the non-traditional fuel composition for nuclear power thermal reactors, basic component of the existing world-wide nuclear power industry, are defined by the following factors. As is known, 233U is able to provide more economical neutron balance in thermal reactors than235U and reactor-grade plutonium. The better neutron balance can result in higher values of the fuel breeding ratio and, as a consequence, in relaxation of the thermal reactors fuel self-sustainability problem. Isotopes231Pa and232U, being fertile and moderate fissionable nuclides, are able to stabilize time-dependent evolution of the thermal reactors power, prolong the thermal reactors lifetime through higher values of the fuel burn-up. Isotope232U, being intense α-emitter, is able to prevent any attempts for unauthorized usage of233U in nuclear explosive devices, i.e.232U can strengthen regime of nuclear non-proliferation. Thus, the hybrid thermonuclear reactors on D-T plasma with thorium blanket can be involved into nuclear power systems for generation of non-traditional, very promising fuel compositions for traditional nuclear power reactors.

The paper aims at studying specific peculiarities in isotope composition of thorium blanket under irradiation by fusion neutron source (FNS) in hybrid thermonuclear reactor (HTR). High-energy (14 MeV) component of neutron spectrum in thorium HTR blanket results in production of non-traditional fissile mixture including not only233U, but also231Pa232U and 234U. Extraction of such non-traditional fuel from spent Th-blanket and its utilization in traditional nuclear power reactors could increase fuel burn-up and strengthen regime of nuclear non-proliferation. The detailed investigations of these positive effects require high-precision neutron-physical analyses of thorium HTR blanket. The results obtained in these investigations are presented in the paper. The following results were obtained: the chosen model of HTR allowed us to form high-energy neutron spectrum in Th-blanket with significant fraction of 14 MeV neutrons; it was evaluated that threshold (n,2n) and (n,3n)-reactions are able to produce significant amounts of non-traditional target isotopes231Pa and232U; it was shown that accumulation of non-traditional target isotopes weakened substantially in depth of Th-blanket. So, it seems reasonable to seek for optimal thickness of Th-blanket and, thus, to find optimal loading of natural thorium.

The vibration of bearings No. 60,206 with radial clearance of 0…0.45 mm is investigated. Analysis of the frequency response (FR) of vibration acceleration reveals information frequencies of 6 Hz, 15 Hz, 26 Hz, and 46 Hz, which coincide with the calculated values. The dependence of the vibration acceleration amplitude on the radial clearance for the specified frequencies is determined. The possibility of rolling bearing wear estimation by vibroacoustic diagnostic methods using artificial neural networks is proved. Diagnostic accuracy with the 4:4-3:1 MI network ranges from 75.6% for a radial clearance of 0.15 mm to 100% for a clearance of 0 mm.

A low-temperature plasma generator of a mixture of nitrogen and propane has been developed, with the possibility of supplying propane to the cathode region, to the arc burning zone, and also to the plasma stream below the arc binding zone. The maximum propane flow rate for a given plasmatron design and plasma-forming nitrogen flow rate, at which the arc is stable, was determined. When propane is supplied into the arc binding zone, the decay products are deposited mainly on the electrodes, and when it’s supplied to the anode after the arc binding, the decomposition products are deposited mainly at the anode exit. The study of the microstructure and analysis of the phase composition of the decomposition products of propane were performed.

The results of thermal modeling of the temperature distribution in the structures of a high-power MOSFET transistor with macrodefects of an electrophysical nature are presented. It is shown that the presence of a defect in the structure of the transistor leads to an increase in the maximum temperature of the channel overheating and an increase in the inhomogeneity of the temperature distribution over the area of the active region of the crystal. The influence of the location of the defect on the value of the maximum overheating of the structure and the gate-source voltage is considered. The developed thermal model can serve as the basis for creating methods for diagnosing MOSFET transistors by thermoelectric characteristics and identifying defective products.