THE PURPOSE. Investigation of the degree of influence of the characteristics of in- plant electrical networks on the reliability of the results in the algorithms for estimating equivalent resistances. METHODS. When solving this problem, a study of the radial power supply scheme of the tool shop section was carried out with the calculation and modeling of equivalent and reference values of the circuit resistances. Algorithms and methods for estimating the values of equivalent resistances have been developed, taking into account the main technical characteristics of in-plant networks.

RESULTS. The data of calculations of the equivalent resistance values of the circuits with an assessment of the heating factor of the conductors and the resistance factor of the contact devices are analyzed. The proportions of the influence of the resistances of the contact equipment and lines, taking into account the number of electric power receivers connected to the power point, on the value of the equivalent resistances of the circuit are revealed.

CONCLUSION. The article develops algorithms for estimating the values of equivalent resistances of in-plant power supply circuits. Nomograms are presented that take into account the number and length of the circuit lines with the allocation of the zone of accounting for the resistances of contact equipment in the equivalent resistances of the circuits. The obtained algorithms and results are recommended to be used to clarify the amount of power and electrical energy losses in the intra- factory networks, which will increase the reliability of calculations.

THE PURPOSE. The purpose of this study is to develop a methodology for determining the coefficient of express analysis of the main equipment of a 35/6 (10) kV transformer substation (TS) to assess its technical condition. A three-level structural complex has been developed for measuring and express-analysis of the technical state of TP. The technical condition of the main equipment of the TP is analyzed according to the selected diagnostic parameters.

METHODS. The TP monitoring system makes it possible to assess the performance of its elements online. Express analysis provides remote monitoring, monitoring of the condition of the operating equipment and forecasting changes in the technical condition.

RESULTS. The proposed method for determining the coefficient of express analysis allows online monitoring of changes in monitored parameters, reducing the recovery time of failed elements, and maintaining equipment in a working condition.

CONCLUSION. The proposed solutions make it possible to move to the organization of maintenance and repair of the main power and electrical equipment of the transformer substation according to the actual state, as well as to improve the reliability and quality of the transmission of electrical energy to consumers.

THE PURPOSE. To consider the actual problem of determining the optimum value of the connected heat load to the cogeneration combined cycle gas turbine (CCGT) of the heat generation profile.

METHHODS. Simulation modeling of operation modes using the "United Cycle" software is applied as a research method of the considered power unit operation. We studied several regimes of heat supply from the considered CCGTs during the heating period with the determination of integral annual indicators, as well as the relative fuel savings compared to the separate generation and the increase in the specific integral economic effect for different values of the cogeneration coefficient.

RESULTS. We found that the optimal cogeneration coefficient for the object of study is 0.49. However, the value of the optimal cogeneration coefficient, determined by the condition of maximizing the specific integral economic effect for the object of research, is also 0.49.

CONCLUSION. Determining the optimal unit commitment, which influences not only the initial investment, but also the expected operating (fuel) costs, is a pressing issue in power plant design. We present a basis for the possibility of using the indicator of relative fuel economy compared to separate generation as an optimization criterion. This parameter is widely used for optimization of combined heat and power units under conditions of planned economy. Under current economic conditions, it is possible to obtain a direct link between the incremental net discounted income from combined production and the relative fuel savings. This method can be used to analyze and optimize the mix of CCGT equipment regardless of geographical area, type of power system, energy resources cost, market conditions, as well as the characteristics of the used equipment.

THE PURPOSE. To carry out a comparative analysis of the spectra of gas-dynamic characteristics of flows in the intake systems of piston engines with and without turbocharging, to assess the degree of influence of the turbocharger on the flow structure in such systems, and also to propose a method for the gas-dynamic improvement of processes in the system under consideration.

METHODS. Due to the complexity of the object of research, an experimental approach was taken as a basis. The experiments were carried out on a single-cylinder piston engine model, which could be equipped with a turbocharger. A system for collecting and processing experimental data based on an analog-to-digital converter was used in the study. Data on changes in local values of velocity and static pressure of pulsating flows in the intake system during the engine's operating cycle were obtained using a constant temperature hot-wire anemometer and a fast-acting pressure sensor. Spectral analysis of functions of flow velocity and pressure versus time was carried out on the basis of the fast Fourier transform algorithm.

RESULTS. The article presents a comparative analysis of the spectra of the amplitudes of the velocity and pressure pulsations in the intake system of an engine with and without turbocharging. Also proposed is a method for stabilizing the pulsating flow in the intake system by installing a leveling grid in the outlet channel of the turbocharger compressor.

CONCLUSION. It is shown that the installation of a turbocharger leads to a significant change in the structure of gas flows in the intake system of the engine. It has been established that the presence of a leveling grid in the intake system of a turbocharged piston engine leads to a decrease in the low-frequency amplitudes of the flow velocity and pressure pulsations up to 30%. It is shown that the probability of failure-free operation of an automobile engine (cylinder diameter – 82 mm, piston stroke – 71 mm) increases by almost 1% when a leveling grille is used in the intake system.

THE PURPOSE. A domestic hot water supply system is proposed, combining a solar collector and a heat pump for the climatic conditions of the city BAC NINH - VIETNAM, capable of providing hot water to 5 users all year round. Justify the performance of the proposed system under these conditions.

METHODS. The solution of the problem was carried out experimentally and by the method of mathematical modeling. The mathematical model is based on the energy balance equations taking into account the efficiency factors. The scheme and principle of operation of the pilot plant and the results of the calculation of the combined hot water supply system based on the monthly average values of the total daily radiation for the location of the solar collector are presented. The system contains a solar collector with vacuum heat-absorbing tubes and an air heat pump as energy sources. With sufficient solar radiation, hot water is generated entirely from the heat-absorbing vacuum tubes, stored in the reservoir of the solar collector and passes through the reservoir of the heat pump to the consumer when the heat pump is not working. In case of insufficient solar radiation, the air heat pump is switched on.

RESULTS. The calculation of the power of the solar collector based on the average monthly values of the total daily radiation and the efficiency of the solar collector, the amount of heat added to the solar hot water supply system, the heat capacity of the heat pump, and a heat pump for the hot water supply system was selected.

CONCLUSION. The results of the experiments confirm the calculations for replenishing the heat deficit for the solar collector with an air heat pump of low power at any time of the year. The calculations are made for a system that provides hot water for the daily needs of five and three people. It is shown that the low heating capacity of the heat pump allows one to reduce the cost of initial investment in domestic hot water supply systems with a solar collector and, accordingly, the prospects of the proposed hot water supply system in Vietnam.

THE PURPOSE. To study the issues of air intake system’s performance as the part of the gas turbines. To estimate the possibility of modeling different performance factors of air intake systems with numerical simulation methods. To develop the recommendations of setting up the grid and the numerical models for researches in air intake system’s performance and assessing the technical condition of elements of it.

METHODS. The main method, which was used during the whole study, is computational fluid dynamics with usage of CAE-systems.

RESULTS. During the study the recommendations for setting up the numerical model were developed. Such factors as grid model parameters, roughness scale, pressure drop in elements of air intake system and some more were investigated. The method for heat exchanger’s performance simulation were created for modeling the air temperature raising.

CONCLUSION. The air intake system’s performance analysis becomes one of the actual topics for research because of the high demands of gas turbines to air, which is used in its annulus. The main part of these researches is in analysis of dangerous regimes of work (e.g. the icing process of annulus elements) or in assessing technical condition of air intake systems and its influence to the gas turbine as a whole. The developed method of numerical simulation allows to get the adequate results with low requirements for computational resources. Also this method allows to model the heat exchanger performance and study its defects’ influence to the performance of air intake system as a whole. 

THE PURPOSE. Determination of the optimal law of swirling of the blades of the last stage of a stationary GTU. Due to the specificity of its operating conditions - in a system with a diffuser - the traditional laws of swirling lead to a non-optimal flow in the diffuser and, consequently, reduce the efficiency of the entire unit and the power plant as a whole. In this paper, we used numerical and experimental methods for studying a three-dimensional flow. Two stages with different laws of swirling were investigated - with the traditional law of constancy of the angle of flow out of the guide vanes along the radius, and with reverse swirling. The same diffuser was used in both cases.

METHODS. Experimental studies were carried out using pneumometric five-channel probes of an original design on an ET-4 aerodynamic stand in the Turbomachinery laboratory of SPbPU. Numerical studies were carried out in the CFX gas dynamic calculation package; the parameters in the corresponding sections, obtained during the physical experiment, were used as boundary conditions.

RESULTS. Integral characteristics of the stage, the vector of flow velocities in various sections were obtained. The experiment was compared with the numerical calculation and showed satisfactory convergence of the results.

CONCLUSION. The optimal swirling law for the last stage operating in a system with a diffuser is forced vortex flow.

Based on the results of the study of the elements of the electrical system, the operability and quality of their functioning are determined by the example of the use of LED filament lamps for lighting during their continuous operation at the maximum permissible ambient temperature equal to 50 °С.

THE PURPOSE. The relevance of this work is determined by the lack of information about the operability and quality of functioning of filament LED lamps during their continuous operation in conditions of elevated ambient temperature, taking place in boiler-turbine shops of thermal power plants, foundries of factories, bakeries of bakeries, in the tunnels of coal mines and divisions of other enterprises. It is established that the working life of the Gauss LED filament lamps with a power of 10 W, containing 4 filaments, is 70-75 days, and with 8 filaments only 22-24 days. Degradation of filament lamps with 8 filaments at the maximum permissible ambient temperature of 50 °С. occurs at a rate of 0.45-0.50 % per day. It is shown that a filament LED lamp with 4 filaments, if it is operated for 4.5 hours a day in conditions of elevated ambient temperature, can work for almost more than one year.

METHODS. The resource of filament and typical LED lamps of different power is considered in comparative terms when they are operated at a relatively high ambient temperature.

RESULTS. It is established that a 10 W filament LED lamp with 4 filaments has an energy resource, as well as a high-quality standard LED lamp. At the same time, the temperature of its body is no more than 40 °С, which is almost 2 times less. By increasing the distance between the filaments due to the use of a smaller number of filaments, it is possible to increase the power supply by 2 times and the corresponding luminous flux by 1.5 times.

CONCLUSION. In preliminary experiments with a filament lamp of the new design of the Diall model, it was found that the use of longer filaments (45 mm) in it, instead of the previously used ones (30 mm), allows to increase the quality of their functioning by about 4 times when they are operated under the same ambient temperature conditions.

ТНЕ PURPOSE. To carry out a comparative analysis of the performance characteristics of the longitudinal movement guides of the external bearing housings of steam turbines, using the principle of rotation to ensure full contact of their lateral surfaces with the lateral surfaces of the guide groove at the base of the external bearing housing of the steam turbine. Compare the manufacturability of elements and their implementation for both existing and newly developed steam turbines

.METHODS. The permissible transverse forces are determined from the strength conditions and compared for the traditional design of fixed longitudinal guides and the design of guides, in which the principle of rotation is used to avoid "biting" of the bearing housing on the guides when temperature misalignment appears along the flanges of the turbine cylinder. Also, the allowable forces are determined and compared from the condition of the absence of plastic deformations in any of the elements of the interface of the guides, the base frame and the bearing housing. Based on the results obtained, the value of the permissible temperature misalignment along the flanges of the turbine cylinder is estimated. The analysis was carried out in relation to the operating conditions of the front bearing housing and HPC of turbines of the T 100/120-130 UTZ family.

RESULTS. It has been established that all the considered designs of guides with pivoting elements make it possible to exclude the occurrence of plastic deformations in the junction of the base frame and the outboard bearing housing at a temperature misalignment of 20°C regulated in most turbine operating instructions.

CONCLUSION. The design of longitudinal keys proposed by UTZ does not require a change in the technology for manufacturing the foundation frames and allows the unit to be modernized during repairs in a CHP. The best performance disc guide design can be used in new turbine designs or factory retrofits.

This article focuses on the study and analysis of the importance of interconnections between electricity systems, which increases with greater probability due to the dependence of all countries and States on electricity and the ease of its transfer between countries in order to supplement their economic and technical benefits.

THE PURPOSE. This study analyzes the dynamic impact of interconnection on circuit stability for synchronous generators in Syrian power grids. In addition, the authors of the article analyzed the dynamic effect of interaction on the stability of the angle of rotation of the rotor of synchronous generators operated in the Syrian power system through the use of dynamic modeling of the country's power system.

METHODS. In the course of the study, the authors used a technique based on the dynamic representation of the power system and the construction of its nonlinear equations, followed by the use of the PSS ® E program. 230-400 kV.

RESULTS. The authors of the article obtained a solution and determination of the system parameters and the separation time of the boundaries of three-phase short circuits in a 400 kV network in addition to determining the angular position of the generator circuits, and thus, its stability was checked, regardless of whether it works independently in the electric power system of Syria or is part of a network.

CONCLUSION. In the course of the study, the authors obtained the following conclusions, such as: an increase in CFCT was found for generating units in the power system of Syria due to connection activation, an increase in transmitted power, which leads to an increase in the stabilization zone after a failure and before the start of connecting electrical systems to the country's power system, as well as it is necessary to conduct in-depth dynamic studies of the entire system in order to represent the effect of the connection on the parameters of the system, taking into account the increase in power.

THE PURPOSE. To carry out an analysis of increasing the efficiency of energy development in the Chechen Republic. On the basis of the current structure of the power supply system of the Chechen Republic, provide indicators of the deficit of consumed electric power, as well as the generation of electricity in the republic. Consider the state of renewable energy sources in the republic and the prospects for the development of energy related to their implementation.

METHODS. The analysis of the development of traditional energy, which is given close attention, is carried out, based on the experience of other subjects of Russia and foreign countries. The question of the application of the methodology for the effective development of regional energy is considered.

RESULTS. A direction for the development of the energy sector of the Chechen Republic is proposed, which should inevitably be associated with thermal power plants using the most modern and efficient cycle today - steam-gas plants (CCGT), which is based on a gas turbine unit running on natural gas, being the only power plant that in the condensing mode of operation, it can supply electricity with an efficiency of more than 58%. The analysis of industrial power consumption of the largest operating and promising energy-intensive enterprises and facilities of the republic is carried out.

CONCLUSION. The introduction of gas turbine plants in the centers of thermal and electrical loads helps to increase the economic efficiency of power plants. It is proposed to carry out fundamental and applied research in the field of renewable energy.

OBJECT. When developing DC test voltage sources to assess the insulation quality of high-voltage equipment, the task is to measure the leakage current flowing through the test object.

METHODS. When solving the problem the authors proposed a technical solution for measuring the current flowing through the test when testing insulation with rectified voltage, which uses a precision resistor, an isolating amplifier, a 2-channel operational amplifier with a unipolar power supply, zero voltage drift, and an ADC of a microcontroller.

RESULTS. The article in the course of the study of the stand of the circuit for measuring the leakage current flowing through the tested object when testing the insulation with rectified voltage, an experimental industrial sample was created, which makes it possible to measure the leakage current value in the range from 10 μA to 1000 μA. The use of the developed circuit for measuring the current flowing through the test object when testing the insulation with rectified voltage makes it possible to calculate the DC component of the voltage signal from the alternating signal and in real time, and, therefore, to quickly monitor the current in high-voltage circuits for continuous monitoring.

CONCLUSION. So the introduction of this sample will make it possible, on its basis, to create a number of digital measuring microammeters that make it possible to measure the leak-age current in high-voltage test installations for testing the insulation of objects from 15 nF to 200 nF, in the leakage current measurement range from 10 μA to 1000 μA. The results obtained can be used in high voltage technology to study circuits for measuring the leakage current flowing through the test object when testing insulation with rectified voltage.

THE PURPOSE. To develop and investigate a mathematical model of an operating object – an individual heat point with two methods of controlling the temperature of the coolant. In the first case, the control of the temperature of the coolant is considered, with the help of a control valve installed on a real object. In the second case, a more reliable and less energy-consuming solution is proposed – replacing the control valve with a frequency- controlled electric drive operating according to the proposed optimal algorithm.

METHODS. When solving this problem, the method of computer simulation modeling, implemented by means of Matlab Simulink, was used.

RESULTS. The article deals with the problems that arise during the operation of an individual heating point. Possible solutions to the problem associated with the failure of the control valve are given. A solution for regulating the temperature of the coolant is proposed, based on the use of a frequency-controlled electric drive of the electric pump. To implement the proposed solution, no redevelopment of the premises is required, only the installation of a frequency converter on the pump already available in the device of an individual heat station is necessary.

CONCLUSION. The conducted research has a practical focus, since the proposed solution is implemented at the existing facility. The use of a frequency-controlled electric drive of a centrifugal pump made it possible to increase the reliability of the existing facility. The results obtained during the simulation allow us to draw a conclusion about the feasibility of using the proposed solution.

THE PURPOSE. To consider the features of development and exploitation of DC-DC power supplies for Arctic conditions, to show the key problems and existing methods of solving them, to identify prospective directions in the design of this type of devices.

METODS. The work is mainly an over-view with the questions of construction, circuit design, control principles, maintaining thermal equilibrium, choosing of electric elements and miniaturization. The first part of the article is devoted to the review of scientific publications and patents, in the second part the idea of using a parallel architecture in frost-resistant power supplies is considered, giving an opportunity to adapt modular principle of device construction.

RESULTS. The article examines the issues of adapting the modular approach to the specifics of frost-resistant power supplies. In this way you can build a self-healing, configurable, easy-to-repair power supply of wide application. With modular construction principle the entire electrical complex consists of parallel-connected cells, placed in one hermetic and heated case (a case with connectors on the surface, as well as the control and display units).

CONCLUSION. Parallel connection of the cells allows to provide a significant power reserve in the power supply, to perform a quick replacement of faulty modules without interrupting the power supply process, to increase/reduce the system power easily by changing the number of working cells. The system acquires special advantages, if the output voltage levels of the cells are adjustable. In this case, it is possible to build a universal configurable power supply of wide application, which is a novelty on the market. If you group the cells on the output, you can use one power supply for several different consumers. The spare parts for the power supply are as simple as possible and consists of ready-made cells and connecting wires. The obtained results can be used in development of fault-tolerant secondary DC-DC power supplies for hard operating conditions.

THE PURPOSE. To consider the problems of controlling the energy efficiency of artificial oil lift. To conduct a comparative analysis of the approaches used to assess the level of energy efficiency and the possibility of energy saving. To submit to a modern possible energy efficiency control system. To identify an effective method for verifying energy efficiency indicators. To propose a concept of an automated control system for energy efficiency of artificial oil lift based on intelligent methods of data analysis.

METHODS. When solving the problem, the method of factor analysis of specific power consumption, implemented in a model, was used.

RESULTS. The article describes the relevance of the topic, considers the features of the use of various indicators of energy efficiency. A model of factors for specific power consumption has been developed. In this article, a concept of an automated energy efficiency control system based on intelligent methods has been proposed.

CONCLUSION. Using the indicator of specific electricity consumption for artificial oil lift, as an indicator of energy efficiency, makes it possible to assess the current level of energy efficiency and identify the potential for further energy saving. To control the specific consumption of electricity at the mechanized stock of production wells, it is necessary to implement systemic energy metering, additional factor analysis of deviations from the planned values. Using of intelligent methods of data analysis selects the factors of deviation of the specific power consumption and ensures the reliability of energy efficiency control.