This article presents the implementation of digital filters used in digital relay protection current measuring elements. Mathematical descriptions of the considered digital filters as well as the computer programs for their coefficients calculation are described. It has been shown that in order to reliable estimate the digital filter performance its input signals waveforms must be close to the actual secondary current waveform of the current transformer to which the digital protection with the estimated digital filter is connected. For these purposes in MatLab–Simulink dynamic simulation environment the power system and the current measuring element models were developed. Performed calculations allowed to reveal that the exponentially decaying DC component which in some cases contains in primary fault current drives the current transformer core into saturation even when its nominal parameters are not exceeded. This results in distortion of the current transformer secondary current which in this case contains higher and inter-harmonics. Moreover, such harmonic content is not completely taking into account during coefficients calculation of the considered digital filters what results in signal magnitude estimation inaccuracy. Comparison of the digital filters response to the above-mentioned input signals allowed to find out such digital filter implementations which enable signal magnitude estimation with a minimum error. Ways of filtering quality improvement concerned with the window functions are proposed. Thus, the joint usage of digital filter and Hamming window allows to achieve the zero value of the signal magnitude gain factor in high-frequency range and substantially suppress all spectral components above 100 Hz. The increasing of the signal magnitude settling time in this case can be reduced by choosing the most optimal parameters of the all components of the current measuring element.

The results of the studies of the combined active filter of a sequential type with a continuous control system for direct current traction substation traction are presented. In the structure under consideration the aperiodic passive LC-filter operates in conjunction with the active one, the operation principle of the latter is being based on the formation of the channel feedback system of automatic voltage regulation of compensation of the variable component of the output voltage of the substation. The structure of a control system of a combined active filter of the series type has been proposed, which specific feature is the use of two parallel running circuits of feedback. The first one generates a signal for compensation of the variable component in a wide range of frequencies. The second one is built with the use of selective links that are configured to low frequency, including the non-canonical harmonic voltage with large amplitude. As a result of analytical studies the expression of the transfer function of the control system of the active filter of the series type with selective link has been obtained. The logarithmic amplitude-frequency characteristics of the combined active filter with and without selective link that had been determined clearly demonstrated the higher efficiency of suppression of the non-canonical harmonics in the second case. In order to confirm the reliability of the analytical results of the control system of the active filter a simulation model in MatLab has been developed. The analysis of the combined active filter of the series type with selective links demonstrated that its use is expedient for quality improvement of the supply the electric rolling stock with direct current energy, also achieving the desired level of electromagnetic compatibility of traction network with systems of railway automatics and communications.

Time and the stopping distance of the electric drive with frequent starting-and-braking modes that contain embedded asynchronous motor with a recessed combined braking device depend on the moment of an electromagnet disinhibition. At the same time other important criteria are taken into the account, i.e. wear resistance of the brake device and the smoothness of the deceleration of the electric drive. In general such an asynchronous motor contains asynchronous engine with squirrel-cage rotor, electromechanical normally-closed brake, electromagnetical slip clutch and control circuit. The mechanical characteristics of the deceleration of asynchronous motor with recessed combined brake device at different moments of an electromagnet disinhibition are presented. The mathematical model is featured and the transients in such a motor are presented. Formation models for computer research were carried out in the Fortran 2008 programming language. Calculation of the system of differential equations was fulfilled by the Runge – Kutta method. The deceleration of the electromechanical brake at various speeds caused different time values and stopping distances. The plots of stopping distance and the braking time at various moments of an electromagnet disinhibition are demonstrated. The optimum moment of switching on an electromechanical brake, providing small stopping distance and the braking time is the time when the speed wвкл = 0,6–0,8 of the nominal. In this case the acceptable number of brake applications for friction linings (compared with mechanical braking) will increase by 1.6–2.8 times. The pilot study confirmed the validity of the obtained mathematical models and discovered patterns.

The existing methods for assessing the energy efficiency of technological systems of water supply and water disposal are examined. The main tool of the existing methods is a settlement-and-analytical method, and, in accordance with the mentioned one, the determining of general and specific electric power consumption is based on actual consumption evaluation, evaluation of pressure and efficiency of the pump unit. However, in practical terms a lot of factors influence on those characteristics therefore affecting the resulting magnitude of energy efficiency and leading to errors in the calculation. These factors include the technical condition of the equipment and piping systems, alterations in the modes of operation of pumping units over time, a significant impact of the ambient temperature on the power consumption, amount of precipitation and the chemical composition of the effluent. As an object of management water supply and water disposal systems are considered as a totality; therefore the assessment of the energy efficiency of pipeline enterprises ought to be based on a systematic approach, whereas the existing methods are mainly based on an analysis of operating modes of individual electrical equipment, not on the whole technological system. The article describes the management system of energy efficiency of pipeline water supply and water disposal systems. The management system is based on information base of statistic data of power, hydraulic and industrial indexes of wastewater management. The original basic mathematical models of common costs and unit costs of electrical power in the water supply and water disposal systems, which are the basis for the solution of the problems of forecasting and the current state assessment of energy efficiency of enterprises, the selection of priority areas of energy efficiency and finding the ways to save energy resources, are presented.

Various aerodynamic design elements and technics (wind deflectors, wind walls, etc.) are utilized for improvement of the thermal efficiency of the natural draft cooling towers, particularly in conditions of cross wind. One of the technical methods, proposed by engineers of Belarus Academy of Sciences, is installation of the ventilation window in the center of the fill. This method is substantiated by the fact that the flow of cooling gas obtains maximum temperature and humidity near the center of the under-fill space of cooling tower and, as a consequence, performs minimal heat exchange. The influence of the fill ventilation window and wind deflectors in the inlet windows of the cooling tower on its thermal performance in condition of cross-wind is investigated in the paper numerically. The cooling tower of the “Woo-Jin” power plant (China) 150 m of the height and 114 m of the base diameter was taken as a prototype. The analogy (equivalence) between the heat and mass transfer was taken into consideration, which enabled us to consider single-phase flow and perform complicated 3D simulation by using modern personal computers. Heat transfer coefficient for the fill and its hydrodynamic resistance were defined by using actual data on total flow rate in the cooling tower. The numerical model and computational methods were tested and verified in numerous previous works. The non-linear dependence of the thermal performance of the cooling tower on wind velocity (with the minimum in vicinity of Ucr ~ 8 m/s for the simulated system) was demonstrated. Calculations show that in the condition of the average wind speed the fill ventilation window doesn’t improve, but slightly decrease (by 3–7 %) performance of the cooling tower. Situation changes in the condition of strong winds Ucw > 12 m/s, which are not typical for Belarus. Utilization of airflow deflectors at the inlet windows of cooling tower, conversely, increases thermal performance of the cooling tower on 10–12 % for the wide range of winds exceeding 2 m/s. Results of the investigation may be helpful for optimal design of natural draft and perspective “hybrid” cooling towers.

Energy security is provided by the minimum required ratio of domestic and imported energy resources. Therefore, in the energy sector energy efficiency should be increased through the use of its own energy resources. Over the last hundred years of development of geological science a preferential distribution of oil and gas fields to areas (blocks) of geological faults, many of which reach the surface of the foundation of our planet, has been determined. The complex process of oil and gas formation is predetermined by geological, geochemical, hydrogeological and other factors. The concepts of organic and inorganic origin of oil and gas are also relevant in the context under consideration. The formation of sufficient oil and gas fields is possible in the presence of highly porous and fractured rocks (for oil) or so-called gas traps. Promising for the discovery of sufficient oil and gas fields are the central and southern areas of the Pripyat trough and the areas on the borders Mikashevichsi-Zhitkovichi ledge. The geological conditions of the areas in the Southern part of the Podlaska-Brest and the North-Eastern part of the Orsha troughs require most thorough investigations. In the area of the Belarusian anteclise, especially near the Baltic syneclise, at great depths in porous rocks the presence of oil and gas deposits of inorganic origin is possible. The use of plasma-pulse impact (that is a very effective one) on the oil and gas underground reservoirs requires a study of the feasibility of their use in new and existing waste deposits. In the exploration of minerals such “exotic” methods, as the assessment of the discharge of helium, radon, radioactive analysis, etc. should also be applied. It is necessary to detect a possible fault zones and prospective search of hydrocarbon energy resources. To ensure energy security of Belarus, the evaluation of the possibility of using associated gas to supply with it a significant part of the country should be fulfilled. The reputed natural deposits of hydrocarbons in the near future will allow us to achieve energy security of the Republic of Belarus in the near future.

A critical analysis of the shortcomings of the existing water purification systems is conducted. In order to ensure environmental safety and energy savings it is proposed to use the combined units, including physical, chemical, physical-and-chemical and biological methods. The attention is driven to the fact that the most effective way to maintain current water purification is an adaptive control system. The shortcomings of the management of water treatment units were revealed and it was proposed to produce their synthesis based on the mathematical apparatus of artificial intelligence systems. Taking into account the requirements of the environmental safety and the need in the energy savings, the energy efficiency criteria of combined system functioning has been developed. At an industrial plant (slaughterhouse wastewater treatment) the compliance of the production conditions of the criterion has been undertaken that confirmed the criterion relevance and usefulness as applied to the synthesis of energy-efficient control systems. A synthetic control system combined the water treatment plants. Having based on the preliminary research and analysis of the current work in the subject area the architecture of a control system of combined water treatment units that use intelligent technology was developed. The key functional of the unit – information-analytical subsystem of the formation control actions including: multilayer perceptrons self-organization Kohonen network, fuzzy cognitive map. The basic difference between the developed design and its analogues is the ability to adjust the settings of equipment adaptively on the basis of processing sensor data, information on the price of consumables, volley discharges of pollutants, a sudden change in the flow and other force majeure. Adjustment of the parameters of the control system is carried out with the use of experimental and analytical data stored in the knowledge base of technological processes.

It is known that the selection of аn acceptably representative sample of the world scientific periodicals to be used as backgrounds of a high-quality research should focus not only on specialized journals, but also on periodicals, the topics and the titles of which are formally not related to the research area. In the present study the determination of the best periodicals to be used in research on “Renewable energy, local and secondary energy resources” has been fulfilled with the aid of four varieties of citation analysis, twelve journals specialized in power production being used as the source items of citation data. The methods of the analysis were clarified and elaborated; the concept and the term “discipline receptivity factor” were proposed. The practical result is a list of 378 world periodicals, that is planned to be used in creating a comfortable scientific information environment by using the world leading databases reflecting the most valuable collection of scientific journals that are necessary for quality performance of scientific research on Priority areas of scientific-technical activity in the Republic of Belarus for 2016–2020 followed by the establishment of an operational system of electoral alert leading experts implementing the respective areas.