POWER ENGINEERING: economics, technique, ecology

SOLUTION OF THE SYSTEM OF STATE EQUATIONS OF AN ELECTRICAL NETWORK WITH AN INSULATION DEFECT OR WITH A SINGLE-PHASE GROUND FAULT

Mykola Grebchenko — 2023-11-16

A method for solving the system of equations of the state of an electric network with an isolated neutral is proposed, which is created based on the results of measuring the current vectors of the load connection phases and the phase voltages in relation to the ground, which allows to determine the occurrence of insulation defects, including single-phase short circuits to the ground, and also to determine distance to the single-phase ground fault location. In the well-known system of equations of the state of the electrical network, the parameters of the longitudinal resistance of the line phases are additionally taken into account, which consist of the resistance to the shorting point and the resistance beyond the point of shorting the phase to the ground. Due to simplification, the replacement circuit with additional line phase resistances turns into exactly the same circuit as the circuit without taking into account the line phase resistances, due to which the determination of the line resistance to the closing point is performed using a known algorithm. The accuracy of determining the distance to the closing point was evaluated on the mathematical model of the network node. It was established that the main factors affecting accuracy include the ratio of the capacitance values of the line and the network, the distance to the shorting point, as well as the resistance at the shorting point. When using automatic correction, the error in determining the distance to the shorting point with a resistance of 0.1 Ohm does not exceed 0.9% over almost the entire length of the line. Analytical expressions for determining insulation conductivity and the distance to a local insulation defect are proposed. The elements of the algorithm for determining the distance to the location of a local insulation defect and the results of the accuracy assessment of the method for the specific case of a phase-to-ground fault, in which the transient resistance at the fault location is not taken into account, are given. Automatic selection of circuits with low resistance at the point of the circuit is ensured by checking the value of the determined active resistance, as well as checking the voltage of the damaged phase in relation to the ground.

CONTROL OF VOLTAGE MODES AS A MEANS OF LOAD REGULATION

Vasyl Kalinchyk — 2023-11-16

The article substantiates the regulation of power consumption modes of production facilities due to the management of voltage modes in the power supply system. It is shown that the regulation of electricity consumption with the help of consumers - regulators (CR) is quite often associated with losses that occur when the CR is turned off. Studies have shown that the management of voltage modes in the power supply system, which affects its level, can play a positive role in increasing the efficiency of the optimization of power consumption modes. It is shown that a comprehensive solution to the problem of power consumption management is expedient both at the expense of CR control and the influence on the voltage regimes of the power supply system. It is shown that the regulating effect of the load is characterized by static characteristics. Solving the problem of forming static characteristics is possible in two ways: through active experiments and based on the integration of static characteristics of individual consumers. Experimental studies were conducted to identify the static characteristics of the load. Experiments were carried out on transformers of the main step-down substation of the chemical industry enterprise, equipped with on-load tap-changers. Experimental static characteristics with linear changes are constructed. The parameters of the model are determined by the method of least squares. Constructed experimental and analytical static characteristics. The voltage mode control procedure for load regulation is implemented in the power consumption control system.

IDENTIFICATION AND CLASSIFICATION OF SINGLE-PHASE VOLTAGE DIPS USING THE METHODOLOGY OF THE SPATIAL VECTOR OF ANGULAR FREQUENCY

Anatolii Voloshko — 2023-11-16

A new method of identification and classification of voltage dips in a three-phase electric network is presented. The method is based on the representation of voltages of the electrical network by one complex variable - a spatial vector of the angular frequency. The main characteristics of the spatial vector, which are used to identify and classify dips, are the major and minor semi-axes, the angle of rotation of the formed ellipse. For balanced dips, the space vector goes in a circle in the complex plane with a radius equal to the voltage. For unbalanced dips, the spatial vector is an ellipse with parameters that depend on the phase of the voltage drop, the magnitude of the dip, and the phase angle shift.

This method introduces a new level of accuracy and reliability in the analysis and classification of voltage dips, making it a tool for improving the quality of power supply and increasing the stability of electrical systems. The use of this method can help reduce the impact of unplanned interruptions in the supply of electricity to the enterprise and home, which is becoming a key task in the modern electricity sector.

DISTRIBUTION ACCOUNTING OF HEAT ENERGY FOR HEATING OF APARTMENT BUILDINGS: TECHNICAL, METHODOLOGICAL, BEHAVIORAL ASPECTS

Yevhenii Mykyta — 2023-11-16

In this paper, a critical analysis of technical literature, methodological guidelines and rules, scientific work of Ukrainian and foreign experts on aspects of the organization of distribution accounting of thermal energy for heating in multi-apartment buildings with vertical heating systems is carried out. An important stage of the strategy for improving the building's energy performance is to organize individual control of energy consumption. For the organization of individual consumption control for heat energy in buildings with vertical heating systems, distribution accounting systems for thermal energy are becoming widespread. Within the framework of this study, a number of aspects and shortcomings in technical standards and legal acts regulating the rules for the organization of distributive accounting would be revealed. Three groups of aspects are defined: technical - related to the justification of using the method of distribution of heating costs according to the types of accounting, temperature measurement, rules for the place of installation of devices, and the presence of a significant number of correction coefficients; methodical - rules for organizing and conducting screenings, interpretation and consideration of correction coefficients, significant simplifications in determining important correction coefficients, lack of methodical provision to prevent abuse by consumers with individual heating systems in buildings; behavioral - the ability to monitor one's own savings, motivation for individual regulation, the presence of individual control over heating consumption without proper control of the temperature regime and flows between apartments causes the possibility of uncontrolled parasitic consumption of thermal energy at the expense of neighbors. Formulated aspects and shortcomings of the existing distribution accounting system require in-depth study in order to avoid unreasonable simplifications, improve the accuracy of the system, and increase the fair distribution of payment for consumed thermal energy among consumers.

RESEARCH OF THE SIDE VENTILATION SYSTEM IN THE POULTRY HOUSE USING CFD

Viktor Trokhaniak — 2023-11-16

Maintaining a standardized microclimate in the poultry house is one of the main factors. The quality of the output ultimately depends on the quality indicators of the air parameters. Keeping a bird requires great efforts and technological solutions. In connection with this study, there is an improvement of the microclimate system in the air environment of the poultry house due to the inclusion of exhaust fans on the rear end wall in an unconventional way. Computational Fluid Dynamics (CFD) using ANSYS Fluent is a powerful tool for predicting the microclimate system in the poultry house as an alternative to experimental studies. The CFD model was performed on the Navier-Stokes equations for convective flows. The calculations use the Discrete Ordinates radiation model and the Spalart-Allmaras turbulence model.

The calculations were made with an air consumption of 21.5 kg/s. The temperature of the outside air is assumed equal to +3 ºС and the thermal radiation parameter is entered. For air removal, Munters EM50 1.5 HP exhaust fans are used in a total number of 4 pcs. Inflow valves Wlotpowietrza 3000-VFG with a total number of 80 pcs., which are placed at a height of 0.21 m from the ceiling (1-8 valves) and 0.81 m for 9-40 valves.

According to the results of CFD modeling of hydrodynamics and heat and mass exchange processes, it was concluded that changing the angle of the spoiler by 73^o allows air to be supplied to the center of the poultry house. The upper air layers near the ceiling and near the side wall have a slightly higher temperature. This is accompanied by radiation from the sun and ranges from +21.5 to +24.5 ℃. Since the bird is a source of heat, and in combination with radiation, the air in the room is partially heated. In the center of the room along the entire height, the temperature reaches +15-16 ℃. At the same time, the pressure drop of the inlet valves is 70 Pa, which allows the exhaust fan to be fully supplied. The air velocity at the inlet of the inflow valves is 11.54 m/s. The average air speed at a height of 0.7 m from the floor level is 0.5 m/s, the temperature is 16.55 ℃.

Thus, the presented scientific research can be used in the future to develop new ventilation systems for poultry houses.

PARAMETRIC ANALYSIS OF NATURAL AIR EXCHANGE IN MULTI-APARTMENT RESIDENTIAL BUILDINGS

Valerii Deshko — 2023-11-16

Most multi-apartment residential buildings built in the 20th century in Central and Eastern Europe do not meet modern energy efficiency requirements. The main part of the thermal energy consumed by buildings is used to heat the supply air from outside, which is the largest share in the energy balance of buildings. The purpose of this research is a parametric analysis of influencing factors on the frequency of air exchange in the room and an experimental study of the concentration of CO2 in a typical apartment. The object of the study is a one-room apartment in a family-type dormitory in the city of Kyiv. The dormitory has ducted natural ventilation. In the work, experimental measurements of the concentration of carbon dioxide were carried out in the premises of the living room, kitchen, corridor of the apartment and in the ventilation channel in the summer period. The indicator gas method was used to measure the air exchange rate. During air infiltration, the average rate of air exchange in the absence of people in the apartment in the living room was 2.41 h^-1, in the corridor - 2.34 h^-1, in the
kitchen - 0.57 h^-1. Under exfiltration conditions, the average values were lower: living room – 0.24 h^-1, corridor – 0.94 h^-1, kitchen – 0.52 h^-1. The dependence between wind directions and the phenomena of infiltration and exfiltration in the premises of the apartment was recorded. As a result of the research, it was established that the most influential parameter of the change in the concentration of CO2 in the room is the release from people's breath. It follows from the simulation results that to ensure the regulatory level of CO2 concentration is not higher 1500 ppm, it is necessary to observe the air exchange in the considered room not lower than the level of 1.51 h^-1 for conditions when 2 people are constantly in the room That is, the mass balance of CO2, which takes into account the number of inhabitants, can be an attractive alternative method for predicting the intensity of ventilation of a building.

ECONOMIC AND SOCIAL ASPECTS OF THE CREATION OF AUTONOMOUS ENERGY REGIONS IN UKRAINE

Valerii Yatsenko — 2023-11-16

The transition to energy generation from renewable sources is a strategic imperative for many countries around the world. The Russian invasion of Ukraine has made the transition to renewable energy more urgent, as countries want to reduce their dependence on fossil fuel imports from Russia. One of the options for increasing energy security, independence, and environmental friendliness of energy production in Ukraine is the creation of autonomous energy regions. The deployment of decentralized infrastructure for the production of green energy is not an easy task, from an economic point of view it is associated with great prospects and problems. Therefore, the analysis of the socio-economic aspects of the full or partial transition to autonomous systems of renewable energy in the regions of Ukraine is relevant.

The purpose of the article is to study the economic and social prospects and problems to the creation of autonomous energy regions in Ukraine based on world experience. The study identified the main problems of the energy system of Ukraine, analyzed the trends of the renewable energy production market, and considered cases of successful creation of autonomous energy regions in different countries of the world. The article formulates the main social and economic perspectives and problems to the creation of autonomous energy regions in Ukraine.

Based on the analyzed examples, the authors singled out the main success factors for the implementation of projects of autonomous energy regions, in particular, the involvement of the local population and business in the development of a new energy network, the creation of an "ecological brand", the possibility of exporting the generated electricity, support for ecological startups, increasing the energy efficiency of housing. The main socio-economic prospects for Ukrainian communities on this path are energy independence, reducing energy supply costs, creating jobs, developing local businesses, building an "ecological brand" increasing the investment attractiveness of the region, improving the quality of life and health of the population. The most critical problems to the successful implementation of the project of autonomous energy regions in Ukraine are the lack of a consistent policy of the central government in the field of green energy, the lack of initiatives of local authorities and communities in this area, difficulties in attracting long-term investments for the implementation of the project.

As the majority of developed countries are still on the path to decarbonization, the need for a global recovery of Ukraine's energy infrastructure can be a chance to significantly modernize the energy system and join the leading players in the market of renewable energy and sustainable development technologies. The study is practically significant because it offers a perspective vision of the development of the energy system of Ukraine's regions to reduce the state's dependence on fossil fuel imports, increase energy efficiency and safety, and economic and social development of Ukraine's regions. Further implementation of this idea requires a study of the volumes of reserves of renewable energy sources in certain regions of Ukraine, an analysis of the means of stimulating the green energy market (for example, "green" auctions or corporate PPAs), the creation of projects of regional strategies for the transition to renewable energy, etc.

THE METHOD OF OBTAINING IONIZING RADIATION BASED ON THE EFFECT OF BRAKE RADIATION

Tymofii Bibik — 2023-11-16

The main problem of the decommissioning of nuclear installations (NPPs) is the processing or disposal of radioactive waste. The main method is the burial of radioactive waste (RAW) in special refrigerated containers that require constant supervision and maintenance. As a result, we have a large area with RW that needs to be maintained, protected and serviced. An alternative is to recycle waste to reduce its dimensions and possibly reuse it. Taking advantage of the phenomenon of bremsstrahlung, it is possible to obtain radiation with a defined energy spectrum. It is possible to ionize the atoms of a certain isotope, which in turn will make it possible to use the interaction of ionized particles with a magnetic field. The magnetic field will be able to move ionized particles, thereby separating them from non-ionized ones.

TARGET INDICATORS OF UKRAINE'S LOW-CARBON POWER SECTOR DEVELOPMENT

Tetiana Nechaieva — 2023-11-16

Ukraine's commitments as a party to the Paris Climate Agreement to reduce greenhouse gas emissions with a gradual increase in ambition provides for low-carbon economic development with decarbonization of its sectors. The Ukraine’s power sector with a 20% contribution to total GHG emissions, due mainly to the fossil fuel combustion at thermal power plants and CHPs with a significant share of coal in the fuel balance, must make a transformation of its structure to reduce the carbon intensity of electricity generation with the expected increase in electricity consumption. The purpose of the article is to review Ukraine's current and prospective obligations regarding its low-carbon development and the formation of relevant target indicators for the development of Ukraine's power sector. The main obligations have been determined regarding low-carbon development contained in the Updated Nationally Determined Contribution of Ukraine with a 65% reduction in GHG emissions in 2030 compared to 1990, the National Economic Strategy for the period until 2030 with the declared achievement of carbon neutrality of the economy by 2060 and carbon neutrality of the energy sector with the maximum reduction of coal use laid down in the Energy Strategy of Ukraine until 2050. The introduction of a carbon border adjustment mechanism with taxation of electricity imported in the EU from 2026 may become a certain obstacle to the import of electricity when the electricity markets of Ukraine and the EU are united, and will become another factor in the need to increase the share of low-carbon and carbon-free generation.

EUROPEAN OFFSHORE NETWORK WITH WIND POWER PLANTS

Valerii Kyryk — 2023-11-16

Problems The growth of electricity consumption and the change in climatic conditions present society with the challenge of ensuring sustainable and ecologically clean electricity production. For many countries, especially in the European Union, the transition to sustainable and ecologically clean energy sources has become a priority.

Objective A general overview and analysis of trends in the development of the network of offshore wind power plants located in the open sea on the continental shelf of European countries

Methodology of implementation The strategy for the development of a single European offshore network with wind power plants was used for research. The study of the effectiveness and advantages of offshore power plants was carried out in the variability of the advanced countries of the European Union..

Results An overview of the electric power industry of European countries that pursue an active policy in the field of offshore energy is given. The statistics on the generation of wind energy, the number and development of wind turbines in Europe are given. The main projects that have been implemented or are in the process of preparation have been considered. An analysis of the measures introduced by the European Union to increase the use of wind energy and reduce dependence on traditional energy sources and achieve carbon neutrality was performed.

Conclusions The European offshore network with wind power plants has become an important component of sustainable energy development in the region. Statistics on the development of offshore wind energy indicate that European countries are actively working on the development of this sector, investing significant efforts and resources.

DESIGN OF ELECTRICAL POWER TELEMETERING SYSTEM USING MICROCONTROLLER DEVICE VIA GSM

Mohanad Abdulhamid — 2023-11-16

Traditionally, reading of energy meters is done by human operators who move from house to house collecting readings. This exercise requires huge labor operator numbers and a lot of time to achieve complete reading of meters in a particular area. This paper endeavors to do away with this problem by using a telemetering system. With this system, power can be measured from a remote site. To achieve this, readings from an energy meter on site are processed by a microcontroller device that then sends the energy consumption information to a Global System Mobile(GSM) module. The GSM module then sends this information using microwaves to a particular mobile subscriber who receives it in the form of an Short Message Service(SMS). The reading is also transmitted to a web based telemetering system through a server. In the remote site, a remote computer which can access the internet is able to obtain data from the server through the internet. The microcontroller is developed in such a way that it achieves communication between the energy meter and the particular server using Transmission Control Protocol(TCP) protocol. Software programs are also developed to facilitate transfer of data to the user at remote site. With the web based telemetering system connected to the internet, electrical energy measurements can be accessed globally. The efficiency of the transmission channel is important for the success of both SMS and web based telemetering systems.

MANAGEMENT OF FUEL CONSUMPTION OF 200 MW POWER UNIT WHEN OPERATING IN FREQUENT START-UP MODE

Vitalii Peshko — 2023-11-16

In the context of insufficient maneuvering capacities in the United Energy System of Ukraine, 200 MW power units are used to cover peak loads in variable operating modes. At the same time, there is a deterioration in the economic performance of power equipment. The efficiency of power generation directly depends on the operating modes of the power unit. Therefore, the task was set to develop a system to rationalize operating modes in order to increase efficiency. The average annual specific fuel consumption was chosen as the objective function. To calculate the specific consumption during the year, the method of bringing all losses during start-up and stationary operation to similar consumption of conventional fuel was used. The following factors were selected as optimization factors: the power unit operation time during the year, the total number of starts from different thermal states for 1 year, and the proportion of starts from different thermal states. The limits of change in the factors were chosen as follows: the number of hours of power unit operation t_i from 2000 to 6500 hours per year; annual number of starts n_i from 25 to 75 times per year; the share of starts from the cold state of metal CS_ifrom 0.1 to 0.9; the share of starts from the hot state GS_j within the share of all starts (hot and un-cooled) from 0 to 1 The developed mathematical model allows to estimate fuel consumption for all possible combinations of operational factors. To demonstrate the operation of this system, calculations were performed for a specific 200 MW power unit with a TP-100 power boiler and a K-200-130 steam turbine. The main parameters of the power unit operation mode were determined using the start-up map and the operating instructions developed by the manufacturer. The calculations established a rational distribution of operating parameters, at which the consumption of conditional fuel is 334-340 g.c.f./kWh. It has been established that the rational number of hours of power unit operation is t_i= 5500-6500 h/year, with the annual number of starts n_i = 25-36 year^-1, while the share of starts should be: from the cold state of the metal CS_i = 0.72-0.9; from the hot state HS_j = 0.1-0.28; from the un-cooled state US_i,j= 0-0.18, and then the difference between the most rational and irrational operating modes is 16.5 % (fuel consumption of 55 g.c.f /kWh).

AN INTELLIGENT MULTI-SENSOR SYSTEM FOR IDENTIFICATION AND ASSESSMENT OF THE TECHNICAL CONDITION OF ELECTRICAL EQUIPMENT USING WI-FI

Dmytro Yakovlev — 2023-11-16

The modern stage of industrial development is characterized by an increasing need for systems to monitor the condition and efficient functioning of electrical equipment. Breakdown or unplanned stoppage of an electromechanical system engine is accompanied by significant economic losses for enterprises. Therefore, the current stage of industrial development is characterized by an increasing need for systems for monitoring the condition and efficient functioning of electrical equipment.

As a result, due to the rapid development of precision manufacturing technologies, many studies have been conducted in the field of multi-sensor measurement and data fusion technologies to improve monitoring capabilities in terms of measurement accuracy and information richness, thereby increasing production efficiency and accuracy. In a multi-sensor system, each sensor independently measures certain parameters. The system then uses an appropriate signal processing algorithm to combine all the independent measurements into a complete set of measurement results.

An accurate assessment of the technical condition makes it possible to predict the term of the next repair of the equipment, increases the reliability and efficiency of its operation, reduces the damage from downtime of the equipment due to accidents, the costs of repair and restoration of operability, reduces the costs of maintenance and operation of the equipment.

This article presents an overview of an intelligent multi-sensor system for monitoring the process and technological state of electrical equipment. Which in real time with the help of sensors makes it possible to obtain information from the environment and draw conclusions about the condition of the diagnosed equipment. The technology of an intelligent multi-sensor system for identification and assessment of the technical condition of electrical equipment has prospects for wide application in industries. Thanks to the most compact dimensions of the installation, we have the opportunity to take measurements in hard-to-reach places, without removing the equipment from work, which minimizes losses from downtime. Also, the use of this system allows detecting the development of a defect in the early stages of development, which prevents and significantly reduces the cost of repairing power equipment when it is out of service.

NON-LINEAR MODEL OF A RECUPERATIVE SHOCK ABSORBER

Anton Novykov — 2023-11-16

This article examines the rationale for using a shock absorber with the function of recuperating mechanical energy into electrical energy. Current trends in the transport industry, regarding the need to use autonomous power sources in the transport infrastructure, are considered. This direction is promising due to the replacement of vehicles with internal combustion engines by electric transport, as well as the need for autonomous power supply of individual nodes and aggregates. The need for autonomy emerges acutely in the conditions of the energy crisis, and at the same time, the lack of energy resources. Special attention is paid to energy recovery using the direct and conversepiezoelectric effect. The structure, chemical and physical properties, principle of operation and practical application of piezoceramic transducers, and the possibility of their use as energy harvesters (generators) are considered. The considered scientific and technical problem, which consists in determining the nature of the negative impact of various types of external oscillations on the functioning of structural elements of vehicles, to reduce which various shock absorbers or dampers are used. This work considers the use of a recuperative shock absorber of vibration loads with the use of a piezoelectricenergy harvester as a converter of mechanical energy of vibrations into electrical energy. Piezoceramic inserts are used as an energy collector in the design of an automobile hydraulic shock absorber. An assessment of the efficiency of recuperation and conclusions regarding the feasibility of use and implementation are provided. The shock absorbers which are installed to absorb vibrations consume a large amount of mechanical energy, converting it into heat which is dissipated into the atmosphere. This energy, without reducing the efficiency of functioning, can be beneficially used by using a piezoelectric generator with piezoelectric ceramics to convert mechanical energy into electrical energy.

VOLTAGE ON THE POWER ELECTRIC DIODES OF A THREE-PHASE BRIDGE COMPENSATION CONVERTER WITH ONE COMMUTATING LINK

Valerii Boiko — 2023-11-16

The operating conditions of power electric diodes of a three-phase bridge compensation converter with one commutating link, which consists of a three-phase capacitor battery and a three-phase group of fully controlled devices, are investigated. This technical solution makes it possible to ensure the recharging of the capacitors of the commutating link and the control of the energy process of the converter. At the same time, the operating conditions of its power equipment also change. The main content of the study is the analysis of the components of the reverse voltage of the power electric diodes of the compensation part of the converter and the dynamics of its change during the regulation of the electromagnetic process by transistors of the commutating link. This is required when determining the class of diodes in the case of introducing a converter according to the scheme under study into production. The study of the magnitude and form of the reverse voltage was carried out for two modes: the transistors of the commutating link are controlled within the framework of the operation of the power electric diodes of their phase and the next one. The volume of research is limited to the analysis of processes at a single frequency of control pulses. As a result, it was proved that on the power electric diodes of the compensation part of the converter, the reverse voltage is less than on other valves. The reason for this is the commutating voltage of the capacitors, which, superimposed on the line voltage of the secondary winding of the converter transformer, reduces the maximum value of the reverse voltage curve of the electric diodes.

INFLUENCE OF DIAGNOSTICS FREQUENCY OF BACKUP POWER SUPPLY ON THE RELIABILITY OF ELECTRICITY SUPPLY

Stefan Zaychenko — 2023-11-16

The article is dedicated to studying the impact of the frequency of diagnosing a backup power source on the reliability of electricity supply and assessing the economic risk of power interruptions in cases of backup or its absence. The study was conducted in the context of developing an automatic diagnosis system for power sources based on internal combustion engines, which has gained additional relevance during times of energy instability caused by the war.

To justify the necessity of installing a backup power source and its timely diagnosis, the relationship between the probability of power interruption before and after backup on a production line is analyzed. The final product of the line results from a sequence of operations, and any interruption in any of them leads to defective production. Based on input data, the cost of one unit of the product and the time required for its production are estimated, allowing for an hourly income assessment for the production area. The time lost during a power interruption, the economic impact of such an event, and the associated risks are calculated.

Similarly, the situation is considered, but with backup in place, taking into account the operational readiness of the backup power source. It is assumed that the technical condition of the backup power source may randomly deteriorate and remain in that state until it is actually restored. The probabilities of power interruption and the associated risks under these conditions are calculated. The obtained data is compared, and recommendations are provided for increasing the reliability of backup.

The results of the research reveal that the installation of a backup power source significantly reduces the risk of power interruption. The inspection period for the diesel generator can be reduced to enhance the reliability of backup, with the maximum level achieved through the use of an automatic diagnosis system for the diesel generator's condition.

OPTIMIZATION OF THE USE OF DISTRIBUTED ENERGY RESOURCES IN LOCAL ELECTRICAL POWER SYSTEMS ACCORDING TO THE CRITERION OF MINIMUM LOSS OF ELECTRICITY

Sergii Denysiuk — 2023-11-16

The issue of optimizing the use of distributed energy resources in local electric power systems (LES) based on the criterion of minimum power loss is considered. It was determined that an important step in optimizing the use of distributed energy resources in the LES is the development of an energy router that allows devices that generate, store, and consume electricity to be combined into a single system at low voltage (without integration into medium voltage electrical networks). The energy router itself can be positioned as a basic device that ensures the operation of LES, the interaction of neighboring LES at the level of energy and information exchange, and the integration of specific LES to medium voltage distribution networks.

It is shown that the basic component of the evaluation of the effective functioning of energy routers and the platform approach in the LES, in accordance with the requirements of the Energy Internet, is the analysis of the components of electricity losses, the influence on their level of various factors, as well as the formation of appropriate energy efficiency criteria and the assessment of the partial impact of LES elements. It is proposed to carry out a description of energy processes during the decomposition of Frize reactive power with the allocation of reactive and active current in the controlled intersections of the system. The decomposition of the QF power into components under the action of various causes (factors) of additional electricity losses in the LES, in particular, due to different modes of operation of generators and LES loads (voltage and current spectra), both during the period of system operation and for an arbitrary period of time, was considered. which is determined by technological factors of system operation.

The use of Frize power made it possible to take into account the energy supply processes of LES loads on alternating and direct current from a single point of view, in particular, to assess the impact of a combination of various factors of the appearance of additional electricity losses; comparison of electricity losses for different time intervals through a selected controlled intersection, when the direction of the flow of electricity is constant or the direction of the flow of electricity changes during separate time intervals; analysis of electricity losses in direct and alternating current systems of LES or hybrid systems, where modified capacities are introduced, as integral estimates of the discrepancy, which determines the influence of distorting factors; assessment of the impact of changes in voltage and current in the intersection of LES of limited power on the components of additional losses; analysis of changes in load consumption of active power according to the first harmonic and higher harmonics as integral indicators.

PERFORMANCE EFFICIENCY INCREASE OF THE MICROGRIDS WITH ENERGY STORAGE SYSTEMS

Denys Derevianko — 2023-11-16

In this paper, an analysis of the potential of using RES for the heat supply needs of public and residential buildings in Ukraine and the world is carried out. It was determined that Ukraine has one of the largest potentials in Europe for the use of RES. An analysis of the "Energy Strategy of Ukraine for the period until 2035 "Security, energy efficiency, competitiveness" was carried out and it was concluded that there is a trend towards decentralization of energy supply and an increase in the use of RES technologies for thermal energy generation. The total primary energy supply was analyzed by types of sources and volumes of generation. On the basis of a comparative analysis of actual and projected data on RES energy generation, it was concluded that there is a trend towards a gradual decrease in thermal energy generation by coal, gas, and oil-fired boilers, and an increase in generation using biomass boilers, solar collectors, and heat pumps. Based on the analysis of the Net Zero strategy, it was concluded that Ukraine and the world will gradually reduce the use of traditional generation and introduce modern technologies not only for the needs of electricity supply, but also for the needs of heat supply.

TRANSACTIVE LOCAL ELECTRICAL ENERGY SYSTEMS: FUNCTIONING FEATURES AND DEVELOPMENT PROSPECTS

Halyna Bielokha — 2023-11-16

Due to global concerns about climate change, the deployment of distributed energy resources and electrical and thermal energy storage systems has been accelerated to minimize CO2 emissions. In addition, the need for optimal energy management of these energy resources was emphasized in order to reduce the need for new energy resources. The concept of transactional energy and, accordingly, transactional systems was introduced for modern energy systems as a system of economic and control mechanisms that allow for dynamic balancing of supply and demand in the entire electrical infrastructure using cost as a key indicator. This ensures cost-effective integration of renewable energy sources and creates incentives for investment and innovative renewal of local energy systems, allowing for management of both supply and demand for electricity. The article discusses the architecture of transactional systems and its components. The main objective function of transactional systems is to minimize the total annual costs of the local system, which supports the continuity of energy supply. To estimate the current cost of electricity, it is necessary to have information on the distribution of investments invested in the project before the start of its implementation, between the periods of project implementation. Considered optimization criteria, the use of which depends on specific goals. It is important to use multi-criteria optimization and control methods to determine the structure of the system and the optimal distribution of energy obtained from different sources in order to maximize the efficiency of the entire system, while contributing to the maximum reduction of emissions to the environment, while minimizing the cost of energy production.