The article examines the most significant risks and threats to energy security in the conditions of integration of the Belarusian NPP into the energy system of the Republic of Belarus. The article also presents an analysis of existing methodological approaches to the assessment of energy security. The risk typology was carried out according to two criteria: the stages of the technological process and the sources of risks. As a result, production, financial and information risks (caused by information technologies) are highlighted. On the basis of an expert survey of specialists of republican unitary energy enterprises and of “Belenergo” State Production Association, a ranking of risks was carried out and the most significant of them were identified. It was determined that the most significant production risks are: depreciation of fixed assets; reduction in the utilization of own generating capacities and reliability of the generating equipment and network; outages that lead to disruption of the functioning of facilities for ensuring the vital activity of the population. The most important financial risks include: the increase in the cost of basic fuel and energy resources; shortage of working capital and investments; lack of sources of financing for the reconstruction of heating networks; reduction of consumer solvency; provision of discounts from tariffs to a significant number of business entities. According to respondents, among information risks the most important ones are the following: failures in the operation of informatization facilities that directly control the generating equipment of power plants, equipment of switchgears of power plants, equipment of substations; hacker cyberattacks; insufficient level of qualification of personnel, lack of interest of employees in the introduction of information technologies. The proposed threat identification and risk ranking at all stages of energy production can be used to develop measures to strengthen the country's energy security and assess their impact on socio-economic development of the Republic of Belarus. 

Nowadays, active power filters represent one of the most efficient means to reduce inactive power components which provides proper quality of electricity at common network connectivity points. Dynamic power losses in the valves that have a significant impact on the efficiency of the converter and, accordingly, determine the feasibility of using these filters in each specific situation, are among their key parameters. Along with the solution of the problem of ensuring the proper quality of electricity at common network connectivity points, the task of reducing dynamic losses in the valves becomes especially relevant. The purpose of the study is to increase the efficiency of active filtration in terms of reducing dynamic losses in the valves while ensuring high-quality voltages at common network connectivity points and currents consumed from the network. To achieve the goal, it is proposed to jointly use a dual-converter active power filter operating in a mode with different conversion frequencies and rated converter capacities, and an interface LCL-filter. Synthesis of converter control is performed. As a control method, the sliding mode control has been used. The efficiency of the proposed system was assessed by modeling in the MATLAB-Simulink application software package. The simulation results confirm the possibility of organizing a mode of operation in which the conversion frequencies and rated capacities of the converters of active power filters are different. In such a case, the currents and voltages consumed from the network at common network connectivity points have an almost perfect harmonic shape; and the phase shift of the network currents relative to the corresponding voltages has a negligible value. It is shown that the organization of the operating mode of converters with different conversion frequencies and rated capacities can significantly reduce the dynamic losses in the switches of active power filters.

Today, increasing energy efficiency in residential heating systems, saving fuel and energy resources, and improving the efficiency of using devices based on renewable energy sources is an urgent issue. The purpose of the article is to develop a mathematical model of the heat balance and conduct a theoretical study of one-story rural houses based on the use of solar energy in a non-stationary mode. To achieve this goal, an experimental one-story solar house with autonomous heat supply was built. The heat supply of the experimental solar house mainly uses solar energy, and when the heat supply load exceeds this load, the traditional boiler device is used. The power supply of the experimental solar house is provided by a solar panel (photovoltaic converter). A heat balance scheme for a solar house with autonomous heat supply and an electrothermal scheme of a physical model are proposed. Based on the proposed schemes, a mathematical model of heat balance and a calculation algorithm based on the heat balance equation of the dynamic state of the heat supply system of a one-story experimental solar house in a non-stationary mode have been developed. On the basis of mathematical modeling, the influence of the heat capacity of the wall structure on the temperature regime of the building was studied. On the basis of the MATLAB-Simulink program, the main temperature characteristics were built, on which the change in the temperature of the internal air of the building was analyzed depending on the ambient temperature. On the basis of the program, a modular scheme of the dynamic model was built. Based on the modular scheme, the results of the experiment on changing the air inside the solar house and the outdoor temperature are presented in the form of a graph. The mathematical model of the thermal balance of the building in dynamic mode and the obtained calculation results are recommended for use in the development of energy-efficient solar houses.

Modern development of society and the economy is generally accompanied by abandonment of non-renewable fuels in the system of existing attitudes toward environmental issues and resource conservation. The paper presents the results of complex operational tests of КВм-2.0 water boilers with automatic stoker and КВр-0.4K at heat supply facilities of the Arkhangelsk region under the typical operating conditions on coal, fuel mixtures, and also peat briquettes and sod peat. Experimental work was carried out using modern methods and advanced technical means. Within the framework of the research on the conversion of boilers to peat fuel, balance experiments were carried out; technical, economic and environmental performance indicators were obtained; the selection and analysis of focal residues were carried out, fine solid and soot particles polluted into the environment were studied in detail. The paper presents graphs of changes in gross efficiency, heat loss with exhaust gas, heat loss with incomplete combustion, and concentrations of sulfur and nitrogen oxides during the cycle between loading peat briquettes into the КВр-0.4K boiler, as well as graphs of changes in the heat balance components and gross efficiency all boiler units under investigation. The conversion of heat generating plants to peat fuel combustion makes it possible to achieve a significant reduction in emissions of solid and soot particles without upgrading ash-collecting plants. Complex experimental studies conducted of existing hot water boilers with a nominal heating capacity of 0.4 and 2.0 MW have shown the possibility, as well as the energy-environmental efficiency of burning briquetted and sod peat in the combustion chambers of these heat generating plants.

The combined use of low-potential soil heat and air flows in heat pump heat supply systems allows for its regulated redistribution in the processes of customers’ consumption. Herewith, the intensity of energy extraction by the soil heat exchanger decreases, excess heat is accumulated with a decrease in the depth of wells, and the costs of installing and operating probe heat exchangers are also reduced. An improved version of the conceptual arrangement of a vapor compression system for heat and cool supply of buildings based on the integrated heat of soil and ventilation air has been developed. Its distinguished features are the possibility of automatic redistribution of generated heat flows in the subsystems of customers’ heat consumption and accumulation of excess part in the soil mass. When the system is operating in the warm season with the extraction of heat only for hot water supply, there is a more intensive accumulation of excess heat of the ventilation air in the soil mass, which restores its temperature in the accumulation mode for further use with the coming of the heating period. Multifactor analytical dependences of the heat flows of the main equipment have been established, taking into account the initial parameters and operating conditions of the structural subsystems for the extraction, transformation and consumption of heat, which are the basis for determining the energy potential of vapor compression heat and cold supply using a binary low-temperature source.

The average number of wells at a typical water intake is 30–40; while the power of the submersible pump is usually 32–40 kW; which means that only at one well water intake the power consumption of electric pumping equipment during the hours of greatest water consumption can reach 900–1600 kW. In the structure of operating costs of well water intakes; the share of electricity costs reaches 85 %. Taking into account the requirements for reducing costs and water tariffs of housing and communal services enterprises as well as of water utilities; energy saving is an urgent task. The article considers the optimization of the operation of groundwater intakes with uneven water supply due to the use of two-column water intake wells instead of typical single-column ones. It is shown that the use of powerful pumps in single-column wells of such water intakes causes a sharp decrease in the dynamic water level in the borehole. On the one hand; this provokes the formation of colmating deposits in the filters due to their aeration; reduces the specific flow rate of the well and shortens the intervals between regenerations. On the other hand; this increases the geometric pressure of submersible pumps and energy consumption for lifting water. The theoretical foundations of determining the supply of pumps installed in single- and two-column water intake wells supplying water to the pressure filter of the water treatment plant are considered. An example of a comparative analysis of the operation of one working well with one powerful pump as part of a water intake of two single-column wells (working and reserve) to cover the entire water supply schedule and two two-column working wells containing one less powerful pump in each column is given. The energy efficiency of these pumping systems is investigated. As a result of calculations; it was found that when combining the operation of pumps of two-column wells during periods of peak; main and partial loads; the annual energy savings will amount to 33 %.

. It is noted that at present, 10 and 35 kV overhead power transmission lines are being laid outside the settlements of the Republic of Belarus on reinforced concrete vibrated (10 kV) and centrifuged (35 kV) poles that are characterized by low reliability and damaging the environment (on account of alienation of land for poles, the need to make a wide clearing for laying in the forest, obstructions by poles and wires of lines to the operation of agricultural machinery, the danger of electric shock to personnel and the public). It is possible to avoid these disadvantages if, instead of overhead lines, power transmission cables with cables insulated by cross-linked polyethylene are used which are characterized by a very low failure flow parameter. Contrary to the prevailing opinion about the higher cost of cable power transmission lines compared to overhead ones of the same rated voltage, it turned out that, taking into account reliability, the cost of electricity lost in the lines for a year, damage to the environment and to the power system caused by the need to perform more expensive emergency repairs (as compared to a planned one), laying cable lines with three-core and single-core cables of a voltage of 10 and 35 kV instead of overhead cables outside the populated area is fairly justified. In this connection, the laying of three-core cables is more preferable. It should be also borne in mind that with an increase in the length of cable lines, the capacitive earth fault current increases, to compensate for which additional devices are needed to be installed in power centers, viz. arc-extinguishing reactors or resistors, accounting for the cost of which (up to 22 % of the cost of one kilometer of cable line) does not significantly affect the conclusions we have drawn regarding the effectiveness of using 6–35 kV cable power lines in an unpopulated area instead of overhead ones, however.