Electrical Engineering and Power Engineering

Increase the efficiency of implementation and interaction of distributed generation with the local electric network

2024-06-10T21:10:18+03:00

Purpose. There is a trend of transition from a purely centralized power supply to a combined one, the number of local decentralized sources of electricity directly in the distribution networks is increasing. Distribution electric networks are transformed into a network with features characteristic of a local electric system, which receives power both from its own distribution electric networks and from a centralized source. Renewable energy has a number of advantages, but there are also disadvantages. Among them - the complication of the operation of electric networks with the growth of the capacities of renewable sources of electricity installed in them and the instability of generation due to their natural dependence on meteorological conditions, if we talk about technical shortcomings, then this refers to the sinusoidal nature of voltages and currents and voltage deviations, ensuring the quality of electricity which directly depends on ensuring the balance of active and reactive power in the electrical system. The purpose of this article is to analyze the effectiveness of reactive power compensation devices as a tool for reducing the threshold of integration of distributed generation sources into the electrical networks of Ukraine. The task is to study the reduction of the integration threshold for distributed generation.

Research methods. Mathematical modeling of an electrical system with distributed generation elements and reactive power compensation devices. The influence of the operation of reactive power compensation devices on the parameters of the electric network is studied. Comparative analysis of network parameters and their change when implementing distributed generation together with and without reactive power compensation devices.

The results obtained. The obtained results show that the use of reactive power compensation devices makes it possible to increase the carrying capacity of operating power lines and transformers, which is especially important when most of the power system schemes where distributed generation is integrated are of radial type, i.e. it actually lowers the integration threshold for renewable generation in the electric network. A very important factor is that the introduction of reactive power compensation devices together with distributed generation solves the problem of stabilization and voltage loss in electric networks, and also improves the quality of electric energy.

Scientific novelty. The method of selecting reactive power compensators for distribution networks has been further developed, which differs from the existing ones by taking into account the presence of renewable energy sources of various types, which allows to increase the efficiency of the interaction of the local electric network with the renewable generation integrated in it.

Practical value. It consists in lowering the integration threshold of distributed generation sources into electric networks by introducing reactive power compensation devices together with them, which affects a number of technological parameters in the node - reduction of power and voltage losses, stabilization and control of voltage, improvement of electric power quality indicators.

Study of unbalance voltage in three-phase networks with different neutral modes

2024-06-10T17:39:45+03:00

Purpose. Determination of the influence of network parameters with different neutral modes on the zero-sequence voltage

Methodology. The research methodology is based on the general theory of electrical engineering and, in particular, on the method of symmetrical components.

Findings. A mathematical model has been developed to establish the nature of the zero-sequence voltage change for different modes of the network neutral. The value of the zero-sequence voltages and the angles between the phase voltage vector with asymmetry and the zero-sequence voltage vector depending on the capacitive asymmetry, capacitance and active resistance of the network insulation for different neutral modes are established.

Originality. Conducted studies have shown that the largest increase in the zero-sequence voltage is observed at the asymmetry capacity, which is 10...30% of the network insulation capacity. Moreover, the relative capacitive asymmetry of the insulation when changing the values of the capacitance of the network relative to the ground has the most significant effect on the value of the zero-sequence voltage in networks with a compensated neutral and is practically excluded when the neutral of the network is completely isolated relative to the ground.

Practical value. For real parameters of the network, based on the results of theoretical and experimental studies, it is possible to judge the efficiency of existing protection devices and use them in the development of new principles and protection devices.

Substantiation of energy efficiency of automated heating technology at HPS

2024-05-31T20:58:22+03:00

Purpose. Justification of rational control parameters of heat pumps to ensure energy-efficient operation of hydroelectric power plants in heating mode. Development of an automated methodology for calculating rational parameters for a complex system of hydroelectric power station (HPS) operating in heating mode.

Methodology. Mathematical analysis and modeling.

Findings. The application of the heat pump to ensure the heating mode at the hydroelectric power station for the needs of heating and hot water supply of buildings is analytically substantiated, as well as the rational parameters of the heat pump, which ensure the efficient heating mode at the hydroelectric power station, are determined. It is impractical and inefficient to pass the full flow of water passing through the hydraulic unit through the heat pump, because in this case the energy consumption in the heat pump compressor is several times higher than the consumption of the hydraulic unit in pumping mode, which devalues the proposed measure as an energy-saving measure. Therefore, the limiting and rational values of the design and operating parameters of the heat pump and heat accumulator, which ensure the heating mode of operation of the HPS to meet the needs of hot water supply, were substantiated. According to the proposed technology, the operation of a hydro unit with a typical capacity of 120 MW in the heating mode for various energy consumptions for the electric drive of the heat pump compressor was investigated. In accordance with these costs, the values and ratios of the electricity and heat generation shares of the modernized HPS changed.

The proposed unconventional technology for converting hydroelectric power plants to the heat generation mode allows for wide effective maneuvering in different proportions of electric and thermal generation, unlike CHP and other power plants. The technology under consideration allows for virtually no consumption of non-renewable energy resources, providing consumers with both electric and thermal energy.

Originality. The technology of using a heat pump to transfer the operation of the hydroelectric power station to the heating mode (heating and hot water of residential buildings) is substantiated. An automated technique for determining the rational parameters of heat pump (HP) for the implementation of HPS heating technology has been developed. The developed automated technique allows to calculate the values of operational parameters of HP for the balance and arbitrary modes, which ensure the heating operation of the HPS to meet the current needs of heating and hot water supply.

Practical value. The use of a heat pump at a hydroelectric power station for heating and hot water supply allows you to save a third of conventional fuel consumption compared to a boiler unit.

A mechatronic system for studying control processes on the example of a "Glide" type aircraft model

2024-04-10T21:43:42+03:00

Purpose. Development of a mechatronic system based on the example of a Glider type aircraft model for studying and researching its control processes.

Methodology. Physical experiment on the developed laboratory bench, computer modelling, calculation and analytical methods.

Findings. In the course of the study, the main processes of glider control were considered and analyzed: the interaction of the pilot's controls and the operating mechanisms of the wing. An analysis of the shortcomings and advantages of existing developments on the subject under study was carried out, taking into account the issues of mobility, economy, simplicity and reliability of implementation, as well as the possibility of using it as a training stand. A laboratory stand has been developed in the form of a mechatronic system based on the example of a "Glider" type aircraft model for studying and researching the interaction processes of control bodies and flight executive mechanisms. The software and hardware complex is connected using the USB interface. A SOC platform with an ArduinoUno microcontroller was used to process processor commands and convert them into aileron movements. The Logitech Extreme 3D joystick was chosen as the control interface. In order to increase the similarity to real systems, a certain delay (inertia) is provided between the moment of the operator's impact on the joystick and the response of the glider. Styrofoam was used as the material of the glider model. Servo drives MG-90S and DS-37 are used to control the position of the moving parts of the glider model. The airframe is rotated using a 28BYJ-48 engine. Software has been developed, the feature of which is easy setup and quick start-up of the laboratory stand. Provide for the possibility of keeping a log, which will allow analysis of the actions of the stand operator. As a result of the conducted research, the features of glider control and the structure of the mechanisms that ensure the control process were determined.

Originality. A mechatronic system of a "Glider" type aircraft model based on an ArduinoUno-based software-hardware complex has been proposed and developed, which differs from the existing ones by the presence of a program that provides easy setup and quick start-up of the aircraft, which allows you to study the interaction of control bodies and executive mechanisms flight.

Practical value. The developed laboratory stand based on the "Glider" type aircraft expands the possibilities of studying and researching electromechanical processes of automatic control systems of complex mechatronic objects.

Fuzzy model of compensation for aging factors of distribution transformers

2024-06-13T15:16:24+03:00

Purpose. This paper aims to evaluate the negative factors that affect the aging of power distribution transformers, develop a fuzzy control model for their compensation, and study the results of applying the proposed model to different modes of the electrical power network.

Methodology. The mathematical method of fuzzy logic was used to implement the control system of the power grid operating modes.

Findings. The article presents a structure based on fuzzy logic for compensating depreciation factors of distribution transformers. A tuning algorithm and measures were developed to optimize the transformer's load level and power factor. The developed model analyzes the parameters and factors affecting the normal operation of the transformer and warns of dangerous factors that threaten reliability and may lead to a malfunction. In addition, the efficiency of PV generating stations, shunt capacitor banks, and energy storage systems installed on the secondary voltage side to preserve the service life of distribution transformers was analyzed and discussed.

Originality. The paper further develops the fuzzy logic models used to optimize the operation of the power grid and compensate for the aging factors of power distribution transformers

Practical value. The results obtained in the paper can be used to build an optimal system for controlling the operation modes of the electric power grid, which reduces the factors that accelerate the aging of power distribution transformers.