The article presents the results of studies of the effects of lightning on low voltage systems of high voltage electrical substations with outdoor switchgears of 110 kV. The topicality of research is associated with a wide spreading of such substations as well as with a high reliability requirements of their work and, also, with their widespread distribution and high probability of lightning strikes to the substation or around it. The highest probable and the most dangerous effects of lightning on low voltage systems of a substation are determined on the basis of critical review and special literature analysis and, also, of systematization of practical information that had been collected during the survey of operating substations. Adequate physical models were developed for the list of hazardous effects based on physical processes of lightning. A model of each effect was studied on the basis of the sensitivity theory. The accuracy and adequacy of the models were verified by means of comparison of calculation results for the models under investigation with the results of calculations fulfilled in accordance with specialized programs, as well as from practical or theoretical data obtained by other authors. The factors that had been included in the models were studied and were defined in accordance with their nature (natural or artificial), the range of possible values in a substation was determined; the coefficients of elasticity were calculated. The obtained results enable to ascertain the contribution of the factor in the effect of lightning and the ability to control the factor. The relationship between the factors and the effects of lightning are shown as graphs. For practical application the information, obtained as the result of the research, was organized in the form of checklists that can be applied when collecting baseline information to develop the lightning protection of the substation, to examine the existing lightning protection, to investigate emergency situations associated with lightning strikes. The results of the study were used in practice during the pre-design survey of substations, development of the design assignment, design of lightning protection of a substation, and during fulfillment of acceptance tests and periodic inspections of lightning protection.

This article presents a comprehensive model for the two-winding power transformer digital differential protection functioning research. Considered comprehensive model is developed in MatLab-Simulink dynamic simulation environment with the help of SimPowerSystems component library and includes the following elements: power supply, three-phase power transformer, wye-connected current transformers and two-winding power transformer digital differential protection model. Each element of the presented model is described in the degree sufficient for its implementation in the dynamic simulation environment. Particular attention is paid to the digital signal processing principles and to the ways of differential and restraining currents forming of the considered comprehensive model main element – power transformer digital differential protection. With the help of this model the power transformer digital differential protection functioning was researched during internal and external faults: internal short-circuit, external short-circuit with and without current transformers saturation on the power transformer low-voltage side. Each experiment is illustrated with differential and restraining currents waveforms of the digital differential protection under research. Particular attention was paid to the digital protection functioning analysis during power transformer abnormal modes: overexcitation and inrush current condition. Typical current waveforms during these modes were showed and their harmonic content was investigated. The causes of these modes were analyzed in details. Digital differential protection blocking algorithms based on the harmonic content were considered. Drawbacks of theses algorithms were observed and the need of their further technical improvement was marked.

The problem of providing electric power quality in the electric power systems (EPS) that are equipped with sufficiently long air or cable transmission lines is under consideration. This problem proved to be of particular relevance to the EPS in which a source of electrical energy is the generator of wind turbines since the wind itself is an instable primary energy source. Determination of the degree of automation of voltage regulation in the EPS is reduced to the choice of methods and means of regulation of power quality parameters. The concept of a voltage loss and the causes of the latter are explained by the simplest power system that is presented by a single-line diagram. It is suggested to regulate voltage by means of changing parameters of the network with the use of the method of reducing loss of line voltage by reducing its reactance. The latter is achieved by longitudinal capacitive compensation of the inductive reactance of the line. The effect is illustrated by vector diagrams of currents and voltages in the equivalent circuits of transmission lines with and without the use of longitudinal capacitive compensation. The analysis of adduced formulas demonstrated that the use of this method of regulation is useful only in the systems of power supply with a relatively low power factor (cosφ < 0.7 to 0.9). This power factor is typical for the situation of inclusion the wind turbine with asynchronous generator in the network since the speed of wind is instable. The voltage regulation fulfilled with the aid of the proposed method will make it possible to provide the required quality of the consumers’ busbars voltage in this situation. In is turn, it will make possible to create the necessary conditions for the economical transmission of electric power with the lowest outlay of reactive power and the lowest outlay of active power losses.

In order to reduce the temperature of cooling water and increase the efficiency of use of power resources the main directions of modernization of systems of technical water supply with cooling towers at steam power plants are presented. The problems of operation of irrigation systems and water distribution systems of cooling towers are reviewed. The design of heat and mass transfer devices, their shortcomings and the impact on the cooling ability of the cooling tower are also under analysis. The use of droplet heat and mass transfer device based on the lattice polypropylene virtually eliminates the shortcomings of the film and droplet-film heat and mass transfer devices of the cooling tower, increasing lifetime, and improving the reliability and efficiency of the operation of the main equipment of thermal power plants. The design of the water distribution devices of cooling towers is also considered. It is noted that the most effective are water-spattering low-pressure nozzles made of polypropylene that provides uniform dispersion of water and are of a high reliability and durability.

Boilers of KVGM and PTVM series are characterized by high values of NOx and CO content in the combustion products. Reduction of NOx and CO content can be achieved by two ways: by installing the condensing heat recovery unit at the boiler outlet and by improving the heat and mass transfer processes in boiler furnaces. Application of the condensing heat recovery units causes pollution of resulting condensate by low-concentration acids. The authors conducted a study in order to determine the effectiveness of the previously applied methods of suppressing the emission of nitrogen oxides in the boilers of these types. Equalization of the temperature field and, consequently, enhancement of heat transfer in the furnace by substitution the used burners by the more advanced ones, the design of which facilitates reduction the emission of nitrogen oxides, were applied to all the upgraded facilities. The studies fulfilled demonstrate that a reduction of NOx emissions in water-heating high power boilers is fairly possible by means of modernization of the latter. The authors have developed the project of the PTVM-30 boiler modernization, which was implemented at a large boiler plant in the city of Vinnitsa (Ukraine). The project included a number of technical solutions. Six burners were replaced by the two ones that were located in the hearth; also the hearth screen was dismantled. At the same time, reducing the total surface area of the heating caused by the exclusion of hearth screen was compensated by filling the locations of the six embrasures of staff burners on the side screens with straightened furnace tubes. Installing the burners separate from the screen made it possible to eliminate the transfer of vibration to the furnace tubes, and – via them – to the boilers setting. Automation provided “associated regulations”. Draught machines were equipped with frequency regulators. During commissioning of the boiler the studies were carried out that related to the identification of dependency of the emission level on the shape of the temperature field in the furnace, in particular, – on the intensity of twist of gas-air mixture at the exit from the burner. We studied two extreme cases, i.e. the case of the maximum achievable level of burner twist that is equal to 45° and the case of no twist. As a result of experiments, it was observed that if a decrease of the twist rate takes place the emission of nitrogen oxides is reduced. The methods of further reduction of emissions of nitrogen oxides have been determined, viz. the device recirculation of flue gases by mixing them in a blast air; conducting the process at low excess of air with controlled chemical underburning when complete oxidation of carbon to CO2 accomplishes outside the furnace at the initial section of the convection part; hydration of blowing air into the humidification amount of 1.5–2.0 % of the nominal output of the boiler.

Wood utilization is a critical direction of the industrial production advancement, where desiccation of wood holds a prominent place. Convective drying in chamber driers is the presentday dominant technique for wood desiccation. Nevertheless, available scientific literature on the subject does not place high emphasis on the issue of gas flow structure inside the drier installations and, in particular, in the clearance between horizontal rows of stacked saw timber. Whereas, the air flowing between horizontal rows facilitates wood heating and moisture removing from the boundary layer. The present article studies aerodynamics of the experimental timber drying test stand at the A. V. Luikov Heat and Mass Transfer Institute of NAS of Belarus. The timber drying test stand geometry structure is complicated, which is why aerodynamics valuation of the drier agent in the chamber involves the software system ANSYS Fluent 14.5. For that end, the researchers developed the convective drier installation geometrical model. A physico-mathematical simulation was developed for sawn timber convective drying aerodynamics in the timber drying test stand of the Heat and Mass Transfer Institute. Based on the computations made, the drier agent flow configuration was analyzed, stagnant pockets identified. It was found that the timber drying test stand was not operating within its optimal aerodynamic conditions. The drying chamber optimal aerodynamic conditions determination includes accounting for an additional canal between the chamber rear wall and the timber stack, absence of the screen above the stack, and presence of the screen between the floor and the stack. As well as variation of the drying agent speed, pressure differrential at the blower, the inter-row gobb amount variation. The paper offers recommendations on optimizing the drying installation aerodynamics based on the numerical simulation results. To this effect, speed of the drier agent in the chamber should be reduced at the expense of reduction of pressure differential at the blower: from initial (150 Pa) to final (90 Pa). It is necessary as well to install an additional screen between the chamber floor and the stack.

As consisted with Directive No 3 of President of the Republic of Belarus of June, 14th 2007 ‘Economy and Husbandry – the Major Factors of Economic Security of the Republic of Belarus’, saving fuel-and-energy resources over the republic in 2010–2015 should amount to 7,1–8,9 MIO tons of fuel equivalent including 1,00–1,25 MIO tons of fuel equivalent at the expense of heat-supply optimization and 0,25–0,40 MIO tons of fuel equivalent at the expense of increasing enclosing structures heat resistance of the buildings, facilities and housing stock. It means, where it is expected to obtain around 18 % of general thermal resources economy in the process of heat-supply optimization, then by means of enhancing the cladding structure heat resistance of the buildings and constructions of various applications – only about 3–5 % and even a bit less so of the housing stock. Till 1994, in residential sector of the Republic of Belarus, the annual heat consumption of the heating and ventilation averaged more than 130 kW×h/(m²×year) (~56 %), of the hot-water supply – around 100 kW×h/(m²×year) (~44 %). In residential houses, built from 1994 to 2009, heat consumption of the heating and ventilation is already 90 kW×h/(m²×year), of the hot-water supply – around 70 kW×h/(m²×year). In buildings of modern mainstream construction, they expend 60 kW×h/(m²×year) (~46 %) on heating and ventilation and 70 kW×h/(m²×year) (~54 %) on hot-water supply. In some modern residential buildings with the exhausted warm air secondary energy resource utilization, the heating and ventilation takes around 30–40 kW×h/(m²×year) of heat. Raising energy performance of the residential buildings by means of reducing heat expenses on the heating and ventilation is the last segment in the system of energy resources saving. The first segments in the energy performance process are producing heat and transporting it over the main lines and outside distribution networks. In the period from 2006 to 2013, by virtue of the heat-supply schemes optimization and modernizing the heating systems using valuable (200–300 $US per 1 m) though hugely effective preliminary coated pipes, the economy reached 2,7 MIO tons of fuel equivalent. Heat-energy general losses in municipal services of Belarus in March 2014 amounted up 17 %, whilst in 2001 they were at the level of 26 % and in 1990 – more than 30 %. With a glance to multi-staging and multifactorial nature (electricity, heat and water supply) of the residential sector energy saving, the reasonable estimate of the residential buildings sustenance energy efficiency should be performed in tons of fuel equivalent in a unit of time.