THE PURPOSE. A study of the influence of coordinated control of electricity storage devices and distributed generation installations on the operating modes of a network cluster, which is an electrical distribution network connected to the AC railway power supply system through a direct current insert (DCI).

METHODS. The studies were carried out using a simulation model implemented in the MATLAB system.

RESULTS. The following disturbing influences were considered: turning off the main power supply of the network cluster from the DCI side for 0.5 seconds; three-phase short circuit with a duration of 0.5 s at the end of a 6 kV cable line with a length of two kilometers. The simulation results showed the effectiveness of coordinated control of electricity storage devices and a turbogenerator with self-adjusting predictive controllers. On this basis, the values of overshoot of the rotor speed are reduced and the transient process time is reduced for all parameters in various modes. For example, the transient time for the generator rotor speed in the mode of connecting an additional load is reduced by three times, and for voltage - by two times.

CONCLUSION. Based on computer modeling, it is shown that coordinated control of electricity storage devices and a turbogenerator with predictive regulators reduces the amount of rotor speed overshoot to almost zero and reduces the transient process time by almost 90%. It is advisable to conduct further research on the application of the method of coordinated control of active elements used in the power supply system to regulate the mode parameters.

PURPOSE. Currently, modeling is one of the most reliable ways to study normal and emergency modes of operation of electrical networks. In this regard, a mathematical model of the 0.4 kV rural electric network was developed in the MATLAB Simulink program.

PURPOSE. Evaluation of the accuracy of the parameters of the operating modes of the 0.4 kV rural electric network obtained by modeling in MATLAB Simulink by estimating the values of the steady-state single-phase short circuit current at different distances from the transformer substation.

METHODS. The currents obtained using the 0.4 kV electrical network model developed in MATLAB Simulink were compared with the currents obtained using other calculation methods (according to GOST 28249-93, the simplified phase-zero loop method and the mathematical model «Project RZA»).

RESULTS. It was revealed that the discrepancy in the results at individual points was 9-11%. When simulating a steady-state single-phase short circuit in MATLAB Simulink, it was found that the voltage of the damaged phase A decreases to 0 V, while the voltages on the two remaining intact phases increase by 1.4-1.5 times, i.e.E. by a factor of 2 to the values of 335-354 V when short-circuiting at the transformer terminals and to the values of 329-338 V when short-circuiting behind a section of a 0.4 kV power line.

CONCLUSIONS. The resulting mathematical model of a 0.4 kV rural electric network in the MATLAB Simulink program can be used to study normal and emergency operating modes, study the modes of joint operation of renewable energy sources with a centralized network, and the processes of switching on backup generation sources.

RELEVANCE: The possibility of a reasonable choice of an alternative strategy for the organization of maintenance and repair (M&R) of the power company's equipment is a guarantee of the successful implementation of its strategic priorities. The tasks in this direction are quite relevant.

PURPOSE: To develop a unified methodology that, from the general standpoint of a risk-based approach, would allow comparing two alternative strategies for managing the assets of an energy company "by periodicity, operating time" and "by technical condition", according to a set of key criteria for the effectiveness of M&R.

METHODS: When solving problems, methods of forming and adjusting schedules for repairs of electrical equipment, calculating reliability and probabilities of failure in the power supply system of consumers, taking into account its circuit features, assessing the technical condition of equipment according to non-destructive testing and diagnostics, comparing the costs of maintaining and restoring reliability and damages from its violations were used.

RESULTS: A risk-oriented methodology has been developed and verified, which makes it possible to evaluate and select the optimal equipment maintenance strategy for the energy company according to uniform efficiency criteria. An algorithmic implementation of the developed methodology is obtained, which is the basis of a computing complex for choosing and making decisions. The verification of the methodology and algorithm is carried out on the example of a real object – a power supply system for oil production consumers using reliable operational and diagnostic information.

CONCLUSION: The results obtained fully compensate for the lack of methodological possibilities in comparing two basic alternative strategies for electrical equipment maintenance based on a single risk-based approach. The developed methodology is a unified decision-making tool at the stage of alternative analysis. The illustration of the methodology by a real numerical example demonstrates the consistency of the solutions obtained with the results of expert assessments and operational experience.

The PURPOSE of this work is to develop technical solutions to increase the efficiency of functioning of centralized urban heating systems by modernizing local heat distribution stations. The article considers the issues of functioning of district heating systems with open water intake. The work presents technical solutions that increase the efficiency of the local heat distribution station with a hot water supply unit. A technological scheme has been developed, the selection of equipment has been made. The feasibility of using the developed technical solutions is confirmed by technical, economic and investment indicators. The objectivity of determining the technical and economic effect of the modernization of the local heat distribution station is ensured by comparing the obtained indicators of the modernized and similar facilities.

METHODS. To fulfill the objectives of the study, the following methods were applied: full-scale tests on a real object; processing of experimental data using application programs; feasibility study in the municipal heat power industry.

THE RESULTS show an improvement in the technical and economic performance of the heating and hot water supply system of an apartment building in Yoshkar-Ola city: reduced network water consumption by 36–39%; temperature drop in the return pipeline was 13.5%; the heat content of hot water has been reduced to 0.168 Gcal/m³ (normative heat content is 0.145 Gcal/m³), the required circulation was ensured in all risers of the hot water supply system. The total losses from October 2021 to September 2022 are 3486,4 Gcal or 11.4% of heat supplied to consumers, which is less than 13% set by the tariff. Compared to a similar house without a regulation depending on the outside air temperature, the consumption of thermal energy during the heating season is reduced by 80 Gcal (10.9%).

CONCLUSION. The new scheme of a local heat distribution station has been proposed, including the regulation of domestic hot water (DHW) recirculation, as well as the installation of a hydroelevator with weather regulation. The developed technical solution is relevant for district heating systems with open water intake. For the first time, an experimental study of the effect of the joint installation of the following equipment was carried out: a pump and a control valve on the DHW recirculation line before the recirculation mixing unit with the return pipeline of the heating system; hydraulic elevator with weather regulation. The results of the study can be used in the feasibility study of similar circuit solutions for the modernization of DHW systems. Operating experience has shown that the application of the developed technological scheme of local heat distribution station has positive effects: reduction of network water consumption, temperature in the return pipeline and heat losses; improvement of circulation in all risers of the DHW system; reduction of thermal energy consumption during the period of the “lower” cutoff of the temperature graph; curbing the growth of tariffs for thermal energy.

To date, easily recoverable oil reserves have already been extracted, so deposits with residual oil reserves or places with weak permeability are of great interest. It is known that oil becomes more viscous when the temperature decreases, which creates difficulties in its production. Therefore, to reduce the viscosity, it is necessary to heat the oil to the temperature at which it is possible to realize its production. The study proposes a mathematical model for calculating the temperature field in an annular porous layer under infinite heating in a downhole reactor for continuous heating of the bottom-hole zone of a formation containing high-viscosity oil and natural bitumen (HVO and NB).

PURPOSE. To construct a heating solution for an infinitely long annular layer in a downhole reactor. To obtain a temperature profile in the cross section of the annular layer and a picture of the temperature field.

METHODS. The equations of the mathematical model are based on the laws of conservation of energy and mass, their study and evaluation are carried out using analytical methods of the theory of differential equations, methods of similarity theory and dimensions, as well as numerical methods for solving boundary value problems. results. In the course of the study, the dependences of the distance at which the set air temperature in the reactor is reached at different values of mass air flow, linear heat flux density and the heat capacity of the mixture were obtained. conclusion. The conducted studies have allowed us to obtain a mathematical model for calculating the temperature field in an annular porous layer under infinite heating in an downhole reactor. The results obtained showed that with an increase in the mass flow rate and the heat capacity of the medium, the distance at which the set air temperature in the reactor is reached increases by 1.6 and 1.5 times, respectively, over the entire temperature range, and with an increase in the linear density of the heat flux, this distance decreases by 0.6 times.

THE RELEVANCE of the research lies in the need to use waste heat, which is a byproduct of the operation of energy machines, to increase the efficiency of their operation. Using the example of introducing a system for recovering condensation heat and using it in an air heating system, the possibility of beneficial use of waste heat generated by refrigeration machines used to freeze the ice arena of a sports complex was confirmed.

TARGET. Development of a system for recycling the condensation heat of refrigeration machines to use waste heat when organizing air heating of a building.

METHODS. Study of engineering systems for the possibility of beneficial use of low-grade heat. Organization of a system for recycling the condensation heat of refrigeration machines in a sports complex. Installation of a measuring stand, including, among other things, a heat meter, a heat calculator, a controller for transferring measurement results to a personal computer, carrying out the necessary calculations, their subsequent processing and analysis.

RESULTS. At a facility with constant operation of refrigeration machines and a need for heating, a condensation heat recovery system has been introduced. The possibility of implementing the proposed system without long-term downtime of the main equipment is shown.

CONCLUSION. The introduction of a condensation heat recovery system increased the energy efficiency of the system, which allowed for 2.6 million rubles. reduce utility bills of the heat supply organization, as well as reduce thermal pollution of the environment by at least 1.4 GW per year.

THE PURPOSE. Consider the experience of use and conduct a study of the electrical power systems of sea vessels to determine the possibility of improving their operational characteristics. Obtain data on noise and vibration levels of electrical power systems elements.

METHODS. The article analyzes the electrical power systems of the Azipod type steering columns of the Baltika icebreaker. The issue of regulating the rotation speed of propulsion electric motors using frequency control based on a DC link and parallel-connected inverter units on IGBT transistors is considered. Motor control on the frequency converter side can be based on direct torque control, scalar and vector control. There are control modes for reducing and increasing voltage.

RESULTS. Typical dependences of structure-borne noise levels of main engines and generators are given. Measurements were taken at various frequencies of engine sound power levels, exhaust gases and vibration of generator sets. Experimental oscillograms of studies of the parallel operation of diesel generator sets were obtained, on which power exchange and common-mode oscillations were recorded.

CONCLUSION. It is proposed to use multiphase AC electric motors to improve performance characteristics, including reducing noise and vibration. The existing experience in using frequency converters based on a rectifier section and inverter units in electric rowing installations with Azipod propellers makes it possible to implement such a change. To do this, it is necessary to parallelize the inverters that supply each of the three phases and provide the appropriate phase shifts.

THE PURPOSE. Develop changes to the building code of rules regarding updating the specific calculated electrical loads of multi-apartment residential buildings. Perform a comparative analysis of the power of technological connection of multi-apartment residential buildings, calculated according to regulatory and technical documents and according to those developed on the basis of actual measured data with an assessment of the effect of updating specific design electrical loads.

METHODS. To achieve this goal, mathematical and statistical methods of analysis were used.

RESULTS. Statistical processing of the specific electrical load of apartments in multi-apartment residential buildings in the Moscow region of a cluster of 11–18 floors for twenty-three months of 2021–2023 was carried out, which made it possible to form statistically significant samples by excluding outliers from them and obtaining their basic descriptive statistics. Based on the results obtained, changes were developed to the regulatory and technical document in terms of updating the specific calculated electrical loads of apartments in multi-apartment residential buildings in the Moscow region of the cluster 11 - 18 floors.

CONCLUSION. The introduction of updated values of the specific calculated electrical load will lead to the selection of power transformers with optimal loading, which, on the one hand, will reduce the “locked electrical power”, resulting in reduced electricity losses, and on the other hand, will reduce the cost of technological connection.

PURPOSE. Study of the features of hydrobiological characteristics of zooplankton development under operating conditions of a fish protection structure similar to a water-air curtain (WAC) at an energy facility.

METHODS. Hydrobiological material was collected, processed and analyzed on the physical and chemical characteristics of water and on the qualitative and quantitative composition of zooplankton in the water intake area of the Zainskaya State District Power Plant. A comparative analysis of our own research and literature data on the characteristics of water in the area of a water-air curtain fish protection structure was carried out. The material was processed using generally accepted hydrobiological methods in the laboratory of the Department of Aquatic Bioresources and Aquaculture of Kazan State Energy University.

RESULTS. It is shown that a fish protection device of the water-air curtain type is a multifunctional technical solution, which during operation changes the physical and chemical characteristics of the state of the ecosystem, especially in the bottom layer. It was revealed that a fish protection structure (FPS) like a water-air curtain does not reduce the species diversity of zooplankton. In the area where the WAC operates, the maximum abundance and biomass of zooplankton were noted compared to control stations. The basis of the number and biomass of zooplankton were crustaceans: cladocerans accounted for 50.2% of the total biomass, copepods accounted for 46.1%.

CONCLUSION. Observations of the state of the ecosystem in the area of operation of the water-air curtain and assessment of water quality based on hydrobiological indicators revealed high water quality in the area where the WAC operates, and an improvement in the environmental situation.