The existing frequency digital filters for allocation of the fundamental frequency of a sine signal are considered and their advantages and disadvantages are noted. Preference is given to the combined digital filter. The existing methods of determining the orthogonal components of a sine signal are analyzed and their disadvantages are pointed out. It is concluded that most of the existing methods for determining orthogonal components are sensitive to the fundamental frequency deviation of the sine signal. This is due to the fact that the deviation of the frequency alters the angle of one sample. The method for solving this problem has been proposed. The essence of the method is the dynamic recalculation of the angle of one sample depending on the calculated frequency. The mathematical model for research of ways of formation of orthogonal components is presented. The model includes transient generator taking into account the aperiodic component, combined digital filter and the methods of formation of orthogonal components under study. The method of transient phenomena formation that takes into account the aperiodic component is described. Coefficients of combined digital filter for sampling frequency of 1200 Hz are given. One of the implementations of the proposed method of formation of orthogonal components in the programming language MatLab is presented. One of the more popular methods and the proposed method acted as the formers of orthogonal components under study. The final part of the article presents the results of the research, as well as their analysis.

Modern conditions for the development of the electric power industry increase the requirements in the field of technical conditions and reliability; thus, in a number of Western countries electric networks are being restructured on the basis of safe, environmentally friendly and reliable composite supports. The article analyzes the structure, design and methods of construction of overhead power lines with composite supports that are more promising than traditional ones. The properties, main characteristics and advantages of materials for the production supports of fiberglass and of wood are considered. The advantages and disadvantages of composite and wooden racks are compared and it is shown that most of the requirements for the supports of overhead power lines are met by composite supports. It is discovered that the existing and promising solutions that enable effective use of composite supports in the construction of an overhead line are quite diverse. Currently, in the electrical networks of Western countries, the most common structural model of the construction of an overhead line is the one the one that alternates composite and wooden supports in a certain sequence. The best option of the use of composite supports along with wood ones is the following ratio: four composite supports to one wooden one (method of construction “4/1”). The advantages of this method of construction of the power line are presented, viz. a significant increase in the mechanical strength of the structure of supports and wires as well as the safety of their maintenance. The results of technical and economic calculation that confirm the advantage of constructing a 10 kV distribution line according to the “4/1” scheme are presented. The implementation of composite supports in the electric networks of the Republic of Belarus in the long term will allow obtaining a tangible financial effect by reducing the cost of operation of the overhead line and because of a significant period of operation of composite racks, which is an undoubted advantage in conditions of the modern market economy. 

Climatic conditions and loads on wires and cables of overhead lines are calculated in accordance with the Technical Code of the Established Practice of TCP 339–2011 and the seventh edition of Electrical Installation Rules. Aviation aerial barrage balls are considered as concentrated loads acting on the wire. The article deals with the mechanical calculation of flexible wires of overhead lines, in which barrage balls warning spheres are installed. The formulas for determining the sag are given for a different number of barrage balls as a function of their number and the coefficient of concentrated forces. This takes into account the difference in suspension heights, tension insulators strings, wind and ice loads. Equations of state are obtained that took into account the weight and wind loads on the wire, as well as the load factors in two planes, depending on the number of barrage balls. Calculations of sag and tension for different span loads have been performed. With the action of wind and ice loads, the tensions and sags increase, in the ice regime the tension has exceeded the permissible value. The case of the appearance of an additional concentrated load in the span is considered.

A quasi-three-dimensional field mathematical model of the electromagnetic field and heat transfer processes in end zone of a powerful turbogenerator has been developed. A model is the intermediate version between two-dimensional and three-dimensional solutions and is based on the numeral calculations in transversal and longitudinal sections of turbogenerator, interconnected by a complex of boundary conditions. On the first stage, a two-dimensional field model of the electromagnetic field in transversal section of central zone of a turbogenerator is considered. Then, taking into account the field distribution in central part, the magnetic field in longitudinal section is simulated. In response to the symmetry of the machine along axial and radial directions, the calculation area of end zone is considered as a half of the rotor section along its axis and the section of the stator core tooth in the tangential direction (circumferentially). Having taken the distribution of electromagnetic parameters obtained in the load mode of the machine as the initial data, the thermal losses in the elements and nodes of the end zone are determined. As a result of solving the joint problem of calculating the electromagnetic field and heat exchange processes, the distribution of heating has been obtained not only on the surface, but also inside the structural parts of the end zone. In particular, it has been found that the maximum temperature of 97.3 °C takes place in the tooth area of the end package of the stator core. This is explained by the combined effect of the main radial field, the axial leakage flux of the frontal portions of the stator and rotor windings, as well as by the “buckling” of a portion of the main flux out of the air gap. In addition, the pressure plate shielding effect is the cause of local field concentration in the toothed zone of the end package. The presented model makes it possible as early as at the design stage to evaluate the efficiency of design solutions for the formation of the end zone of the turbogenerator stator for different load modes of the machine, including the modes of consumption of reactive power.

The one-dimensional axisymmetric problem of initiation of a combustion wave in an oil-saturated reservoir is solved numerically. Two combustible components, viz. liquid (oil) and solid (kerogen, oil sorbate) were considered. The influence of the abovementioned components on time of the hot site ignition and combustion front speed was simulated and analyzed. It was demonstrated that growth of the mass fraction of liquid component (the total heat content being preserved) results in retard of formation of the hot site near the well and in reduction of the maximum temperature of the combustion wave, disregarding of the higher reactivity of liquid combustible. Simulation revealed existence of the two “peaks” of thermal front velocity. The first one corresponds by time to ignition of combustion site. The second one corresponds to a moment when the solid component combustion front overrides the oil displacement front. Calculations shown, that thermal wave propagation velocity, at least after passing the “peaks” and transition to quasi-steady regime, does not considerably depend on mass traction of the fluid component in the system. A typical term of the exothermic reaction site formation may increase from 50 to 200 days in case of growth of the liquid component content from 30 to 80 mass % at the considered thermal conditions in the oil reservoir. Thus, the implementation of the thermo-gas method in high-productive layers increases the likelihood of difficulty of initiation of a fire. Therefore, the study of the regularities of intra-combustion in such cases is of a particular interest. For instance, the task of combustion site ignition may be resolved by increase of oxygen content in blowing-gas or by means of non-steady (periodical) blowing. It is found that taking into consideration of highly reactive liquid component results in widening (diffusion) of the thermal front, which may play positive role in its spatial thermo-hydrodynamic stabilization. The results of simulation may be utilized for development of technical projects of oil recovery via in-situ combustion, for designing of furnaces utilizing multicomponent fixed layer fuels and for thermochemical investigation of multicomponent fuels.

To solve the problem of increasing the efficiency of operation of thermal networks, placed in impassable channels, the authors previously proposed the scheme-and-structural decision of the regenerative-utilization heat consumption. The technology of forced ventilation of the channel by external followed by the cooling of air and utilization of the withdrawn heat is presented. Research of processes of heat exchange between a stream of air and pipelines of network water on the one hand and between a stream of air and walls of the channel on another hand is a determinant for realization of the presented technology of increase of efficiency of operation of the considered heating mains. Convective heat transfer with the listed components of the channel structure is quite difficult to reduce to any canonical form which makes it possible to use the available design dependences. It is immeasurably more difficult to find a solution when considering the processes of forced convection jointly. Heat exchange takes place in a channel of complex shape that is determined by the presence of supports, compensators and turns along the length of the channel. In the cross section, the sizes of the structure and the restriction of the air flow are determined by a standard size range of diameters of the network water pipelines. Under these conditions, the use of any real experimental facility is associated with unacceptable idealization and the corresponding error, unsuitable for practical use. Full-scale tests can be considered only to verify the adequacy of the experimental results. The way out of this situation can be a usage of a virtual experimental facility created on the basis of a standard software package (in the case under consideration the ANSYS was used). The approaches of creating a virtual experimental facility for the study of heat transfer and aerodynamics in the blown impassable channels of heating mains and methods of conducting experiment using the theory of its planning are considered.

The scheme of carbon dioxide cogeneration and trigeneration plant with the use of secondary energy resources in the form of combustion products or flue gases that enables to produce electricity, thermal energy and cold for centralized and decentralized supply of consumers simultaneously, is presented. In addition, the plant can produce liquid and gaseous carbon dioxide. The main elements of the plant are a heating unit, a turbodetander unit and a carbon dioxide unit for the production of cold, liquid and gaseous carbon dioxide. A thermodynamic calculation and a brief exergy analysis of the plant were carried out. In the proposed plant, off-gases from glassmelting, metallurgical furnaces, heat power facility and other energy facilities with a secondary energy temperature of 250–400 °C and above can be used as secondary energy resources. The heating unit of the installation has been designed to produce thermal energy for heating and hot water supply systems. The carbon dioxide unit has been designed for the production of cold, electric energy and carbon dioxide in liquid and gaseous form in order to ensure the operation of the plant and the use for commercial purposes. The cold in the plant can be obtained in two evaporators operating at different boiling temperatures. At a higher boiling point of carbon dioxide, cold is used in air conditioning systems and in centralized cooling and storage systems, while at a lower boiling point of carbon dioxide – in freezing and storage systems. For the implementation of the reverse carbon dioxide cycle, a three-stage carbon dioxide compressor with a receiver after the third stage is used. To reduce compression performance of the compressor, complete intermediate cooling of carbon dioxide between stages should be provided.

The first and one of the most important functions of management is planning. At the same time, in the current market conditions, the time for the implementation of this stage is very limited. In many ways, this applies to the oil and gas industry all the same. Due to the reduction of the resource base of the industry, the share of super-profitable projects has decreased significantly. Extraction of hard-to-recover oil and gas reserves is associated with active investment activities and with the need to introduce expensive technologies and equipment. The most common type of investment project associated with the geological and technical activities is being considered in the present paper. In order to increase the economic efficiency of the geological and technical activities it is proposed to implement an automated model at the stage of planning. This model, on the basis of the generalized geological, technological, statistical, macroeconomic and economic indicators, allows to solve quickly the following problems: of more precise and prompt planning the expenses on carrying out geological and technical actions; of defining minimum admissible profitable level of an oil flow rate after carrying out geological and technical actions; of determining the most economically justified duration of the overhaul of the well; of organizing the projects of geological and technical measures according to their attractiveness. As a result of the implementation of the automated model, an efficiency matrix for a particular field was compiled that determines the impact of the necessary investments and planned flow rate on the economic indicators of the project. The use of this matrix made it possible to exclude several inefficient geological and technical measures from the plan. The method of ranking based on the calculation of the integrated efficiency coefficient has been developed. On its basis, the issue of making optimal management decisions taking into account the impact of risk assessment in the case of projects with the same economic efficiency is solved.