Elements Of Power Supply Systems Research Articles

ВЛИЯНИЕ ЭКСПЛУАТАЦИОННОЙ СКОРОСТИ НА ПАРАМЕТР ПОТОКА ОТКАЗОВ ЭЛЕМЕНТОВ СИСТЕМЫ ПИТАНИЯ ДВИГАТЕЛЕЙ АВТОМОБИЛЕЙ КАМАЗ-43118

The problem of the effect of operating modes on the actual reliability of fuel equipment elements of diesel engines is considered on the example of KAMAZ-43118. The study objective is to find out the effect of operational speed on the failure flow of the power supply system elements of KAMAZ-43118. The task is to evaluate the changes in failure flow of the power system elements depending on the operating speed of the vehicle. For this purpose, the calculation of the main statistical characteristics of the distributions of operation time for the system under study failure is performed, as well as a hypothesis about the form of a mathematical model of the influence of operational speed on the failure flow of elements of the diesel engine power supply system is proposed and experimentally confirmed. The work novelty is that conducted research will make it possible to use the inherent resource of the vehicle more completely. In order to realize the fullest possible resource of vehicles and increase the actual reliability of the power system elements, a method is proposed to correct the frequency of technical influences on the system under study.

FEATURES OF THE FUNCTIONING OF SMALL POWER SOLAR GENERATION IN THE IPS OF UKRAINE UNDER THE CONDITIONS OF THE GREEN TRANSFORMATION

Within the framework of the transformation of the energy system in terms of ensuring the further development of small distributed generation from renewable energy sources, a new support model for low-power facilities is proposed, which will facilitate the commissioning of new generation entities. In the paper, research is conducted on the problem of small generation in Ukraine, which is faced by the power system, in the conditions of an increase in the share of distributed generation. An assessment of the impact of small solar power plants on the operation of the electrical network, including rooftop ones installed in households, was carried out. Typical schemes of connection of SPPs to the electrical network are considered and their influence on electrical equipment, elements of power supply systems and principles of operation are determined. It has been established that the integration of new renewable energy entities, including low-power SPPs, causes a number of technical problems that have an impact on the operational characteristics of the network, security of supply, and reliability. The main ways of solving the problems of losses and deviations of the voltage level in distribution networks, when connecting small SPPs, have been formed. In further research, the obtained results will be used to develop proposals for connecting low-power entities to the electric network and their formalization in the form of provisions of regulatory and technical documents.

Increasing the energy efficiency of modes of distribution networks with photovoltaic stations

Purpose. Establishing the regularities of changes in influence of power quality indicators caused by the operating modes of photovoltaic (PV) station inverters on the operating modes of distribution networks’ equipment to improve their energy efficiency by reducing power losses. Methodology. To solve the scientific problems, the following methods are used such as: the method of harmonic analysis (Fourier integral); decomposition of the current spectrum by amplitude-frequency component using Mdaq-14 hardware and software platforms and LabVIEW software; the method of data correlation analysis to determine the higher harmonic current dependence on the load of an on-grid inverter; mathematical and physical modeling in the development of a way to improve the energy efficiency of on-grid inverters of PV stations. Findings. The conducted studies on electromagnetic compatibility indicators of grid photovoltaic station inverters in stationary and dynamic operation modes made it possible to establish the characteristic regularities of changes in the spectrum and amplitudes of higher harmonic components depending on the level of inverter loading. Hyperbolic dependences of the change in the sinusoidal signal distortion coefficients of the harmonic component on the level of inverter loading were experimentally established. A method has been developed for reducing the electromagnetic interference levels caused by photovoltaic station converters by implementing a circuit solution and algorithm for loading on-grid inverters in non-stationary modes in order to improve their electromagnetic compatibility and increase the energy efficiency of distribution networks with appropriate decentralized sources. Originality. The regularities are established of influence of the operating mode’s parameters of photovoltaic station inverters on the indicators of electromagnetic compatibility in their power supply system, including taking into account special circuit solutions, which allows increasing the energy efficiency of distribution network modes. Practical value. The method for reducing the electromagnetic interference levels generated by photovoltaic station inverters by implementing the proposed circuit solution and algorithm for loading the on-grid inverters in non-stationary modes is universal and can be applied to any photovoltaic station. This will help to reduce the power losses and electromagnetic damage to equipment from the action of higher harmonic components. Granting the established regularities of higher harmonics influence will allow one to take into account the impact of the relevant indicators on the additional insulation heating of power supply system elements and to assess the corresponding electromagnetic damage, to provide recommendations for consideration of the modes in calculating methods and PV equipment selection.

Forecasting of Electricity Consumption by Household Consumers Using Fuzzy Logic Based on the Development Plan of the Power System of the Republic of Tajikistan

Seasonal fluctuations in electricity consumption, and uneven loading of supply lines reduce not only the energy efficiency of networks, but also contribute to a decrease in the service life of elements of power supply systems. To solve the problem of forecasting power consumption, it is proposed to use the theory of fuzzy sets to assess the effective development of the energy system of the Republic of Tajikistan. According to the statistical data of power consumption for the previous period, a fuzzy logic model with membership functions is proposed, which makes it possible to evaluate consumer satisfaction using the criteria unsatisfactory, satisfactory, conditionally satisfactory, and satisfactory, as well as the efficiency of the consumption mode of compliance using the criteria high, medium, and low, allowing the evaluation of the efficiency plan for the development of the energy system of the Republic of Tajikistan. To obtain and set more accurate data on electricity consumption, calculations were made for the winter period of the year. Based on the proposed calculation model of fuzzy logic, a quantitative component of electricity consumption, the corresponding satisfaction of the consumer, and the efficiency of the regime for nine cities of the Republic of Tajikistan were proposed in the form of diagrams of seasonal electricity consumption. The obtained seasonal power consumption makes it possible to improve the accuracy of estimating power consumption, thereby equalizing the balance of consumption and generation.

MODELING OF RELIABILITY OF 6…10 KV OVERHEAD LINES FOR POWER SUPPLY OF OIL AND GAS FACILITIES

The article considers the issues of assessing the impact of meteorological factors on the functioning of the most damaged overhead lines (OL) in the region under consideration, the modeling of which, taking into account the weather model, gives more realistic indicators, in the form of average residence time of the process in states, operating time for failure, recovery time, the number of transitions to an inoperable state. It is shown that from the point of view of the causes of damage to overhead lines leading to failure, the climatic impact is crucial: dust storms, pollution, sharp temperature fluctuations. The research methodology was based on the classical apparatus of mathematical statistics and reliability theory. To develop models of reliability of the main elements of power supply systems (PSS) - overhead lines (OL), the theory of Markov random processes and modeling of processes and systems was used. In terms of practical value, models have been developed that take into account environmental conditions and the main indicators of PSS reliability have been determined for use in design and operational practice: average time to failure, average recovery time and average number of transitions to an inoperable state. The use of Markov models describing PSS at the level of random processes makes it possible to apply in practice methods for assessing and predicting the reliability of PSS operating under the influence of the external environment.

Анализ технологических направлений электрификации объектов добычи углеводородов на слабоосвоенных территориях.

The article considers modern technological directions for the electrification of hydrocarbon production facilities in the poorly developed or hard-to-reach territories of the Arctic, the Far North or offshore fields, due to the remoteness of the Arctic and Far Eastern regions from existing large energy hubs, which makes it practically impossible to use a unified energy system of RF (UES RF) as the main source of electricity for needs of the oil and gas industry. The conditions of the UES RF using necessitates the additional generation sources for oil and gas companies and the solution of related issues of economic and environmental efficiency of technological projects for the electrification of hydrocarbon production facilities in hard-to-reach and poorly developed territories. The study performed a cluster analysis of literary sources in order to determine the current trends in the electrification and power supply of the oil and gas industry. An assessment of the conditions for the application of modern technological directions for the electrification of hydrocarbon production facilities in the poorly developed and hard-to-reach territories of Russia is presented. The system analysis covers electrification options using gas-fired generators; based on the integration of renewable energy sources and their combination with traditional types of electricity supply; using complexes of unified energy networks for several offshore production facilities and additional energy centers. The study of technological directions for the electrification of hydrocarbon production facilities in poorly developed territories is the basis for further practical application of the results of the analysis in the field of pre-project planning and evaluation of proposed technological solutions based on the rational choice of a power source for remote fields, taking into account the optimal composition of equipment and the location of elements of power supply systems, construction schedule and indicators of the cost of construction and operation of energy supply systems.

Learning algorithm of artificial neural network factor forecasting power consumption of users

Seasonal fluctuations in electricity consumption, an uneven load of supply lines reduce not only the indicator of energy efficiency of networks but also contribute to a decrease in the service life of elements of power supply systems. Revealing the patterns of such fluctuations makes it possible to build models of power consumption, predict its dynamics, which in general will contribute to ensuring the energy efficiency of urban electrical networks and increasing the reliability of power supply systems. A computational, computer and neural network model is proposed that allows to increase the accuracy of the forecast of electricity consumption by household consumers. Based on the developed mathematical model, taking into account the obtained factor coefficients - ti, h, c, s, k for 2020 for 9 cities of the Republic of Tajikistan, monthly coefficients characterizing the terrain conditions (αi) were calculated. The results obtained using the proposed method was compared with the results of a computer and neural network model.

Automation of diagnostic tools for agricultural power transformers

Power transformers are the main elements of power supply systems and are used in agriculture and industry. When testing an agricultural power transformer, no-load and short-circuit modes play an important role. The system for checking the power transformer is proposed to implement using a modern digital analyzer. Part of the measurements should be performed without disconnecting the power transformer from the network. At the same time, the test time is reduced, the accuracy and the ability to automate the processing of measurement results are increased.

COMPLEX-CLOSED POWER SUPPLY SYSTEMS AND CALCULATION OF THEIR ELECTRICAL MODES

When creating and improving power supply systems, steady-state calculations are the most common, they contain nonlinear elements in the form of generators and loads, therefore their steady-state mode is described by nonlinear equations. The solution of such equations is possible only by iterative methods, which is associated with the problem of convergence of the iterative process. Due to some features of electrical systems, which are inherent, including power supply systems of the agro- and forestry complex, the convergence of the iterative process may be slow and not even secured. (Research purpose) The research purpose is developing a method for calculating the steady-state modes of power supply systems that meets the condition of convenience of implementation on an electronic computer and removes the problem of convergence of the iterative counting process. (Materials and methods) Proposed a direct calculation method with cyclic correction of the initial information for each cycle in order to take into account the nonlinearity of elements of power supply systems. (Results and discussion) The calculation formulas for determining the intrinsic and mutual resistances that underlie the proposed method are given, their main feature is that they are distributed with elements included in the nodes corresponding to sources and loads, and obtained by the authors as a result of the transformation and solution of nodal equations. It was established that the method is implemented through the operation of the following algorithms: calculation of intrinsic and mutual resistances; calculation of current distribution, that is, determination of currents in the branches of the network; calculation of voltages in all nodes of the power supply system; calculation of power flow distribution in order to subsequently identify power losses and electric energy consumption. (Conclusions) It was shown that the derived universal calculation expressions can also be used for equivalence purposes. It was revealed that the proposed method and the algorithms implementing it are relatively easy to program and provide the necessary speed and accuracy of calculations; they are designed to solve practical problems related to the design and operation of complex closed power supply systems, increasing their reliability and efficiency.

MATHEMATICAL MODELS OF RELIABILITY OF POWER SUPPLY SYSTEMS

Ensuring reliability is one of the most important issues in the creation and operation of any technical system. This is especially important for complex systems, such as power supply systems with internal and external connections consisting of many elements. The task of ensuring the reliability of power supply systems includes a whole set of technical, economic and organizational measures aimed at reducing damage caused by violations of the normal mode of operation of electricity consumers. To obtain information about the reliability of elements of power supply systems, it is necessary to study a fairly large number of identical elements over a long period of time. In the real conditions of an industrial enterprise, this creates certain difficulties, so it is possible to conduct an accelerated reliability test using mathematical modeling [3].
 The article discusses some ways to solve the main problem of reliability theory - building a mathematical model and obtaining criteria for selecting optimal options for power supply systems. In this paper, the main materials for calculating the reliability of power supply systems using the mathematical apparatus of probability theory are presented.

Model of a Photovoltaic Module for the MatLab/Simulink SimPowerSystems Library

The relevance of research is caused by the increase of the number of photovoltaic power plants in the Republic of Belarus and, accordingly, the need to solve problems of diagnostics of photovoltaic modules. A new Simulink model of a photovoltaic module focused on using the standard SimPowerSystems library of power supply system elements (a part of the MatLab/Simulink) is proposed. The model allows altering solar irradiation values for each solar cell of the module. The use of the model also makes it possible to obtain calculated values of voltages and currents at the photovoltic module output. In addition, the model provides the simulation of individual solar cells shading in the module. The developed Simulink model operates on the base of a well-known exponential dependence describing the volt-ampere characteristic of a photovoltaic module, and also takes into account the real circuit of the module with bypass diodes. The series resistance of the photovoltaic module is calculated by the subtraction between its experimental and theoretical volt-ampere characteristics for conditions that are close to normal. The Simulink model of the SF-P672300 module contains 72 nonlinear elements implemented on the basis of controlled current sources and connected in series. The model solved the problems of the algorithm stability for calculating algebraic cycles by introducing constraint the current and the voltage parameters. Experimental studies for the fully illuminated and partially shaded SF-P672300 module have demonstrated that the maximum relative error of the developed Simulink model does not exceed 15 %. Experimental and theoretical current-voltage characteristics of the SF-P672300 module under full illumination and partial shading are presented. The presented Simulink model may be used both at the design stage and at the operation stage of photovoltaic power plants in order to simulate and analyze the factors that affect the operation of them.

Calculation of Power Losses in a DC Traction Power-Supply System with Allowance for Train Traffic

Based on an analysis of a train schedule, the probabilities of the occurrence of a certain number of trains in the intersubstation area are calculated. The currents and power losses in various traction power-supply system elements are determined for a fixed number of trains in the intersubstation zone. It is found that the obtained values of currents and power losses correspond to the probability of their occurrence, depending on the number of trains in the intersubstation zone. For this reason, it is concluded that the average values of currents and power losses in the traction network elements can be considered as mathematical expectations. Due to the fact that the electric traction load constantly moves through the intersubstation area with uneven current consumption in the presence of a different number of trains on the section, the available analytical calculating methods for power-system parameters have a significant error and make it possible to calculate the required values with a sufficiently high accuracy only for some railway sections. The use of probabilistic calculation methods for traction power-supply systems is a more universal tool for solving electrical problems in the power supply of railway transport, such as determining power consumption and power losses in the traction network.

АНАЛІЗ МАТЕМАТИЧНИХ МОДЕЛЕЙ ЛІНІЙ ЕЛЕКТРОПЕРЕДАЧІ

The article investigates the mathematical model of the power supply system elements – transmission lines. It is shown that transmission lines have a variety of mathematical models. They are the basis for the study of the operating modes of power grids. They reflect all the peculiarities of physical processes under steady state and transient modes and must ensure sufficient accuracy of the results obtained. The type of mathematical model of transmission lines depends on the accepted simplifications, which allow to consider a separate research problem. The purpose of the article is to develop a mathematical model of the power transmission line for the study of the power supply system modes, with the possibility of its application to take into account all structural features of overhead and cable transmission lines, and with the possibility of use in asymmetric modes.

DETERMINATION OF THE VALUE OF SINGLE RAPID VOLTAGE CHANGES IN NETWORKS SUPPLYIND ELEKTRIC WEIDING INSTALLATIONS

The article deals with the tasks of ensuring the required quality of electricity in modern power systems of industrial enterprises. The main tasks of designing and operating modern power supply systems for industrial enterprises are in addition to the rational choice of elements of power supply systems, it is also to ensure the required quality of electricity at the terminals of the power receivers. Ensuring the required quality of electricity is generally associated with the electromagnetic compatibility of the supplynetwork. The intensification of production processes is associated with the improvement of technological processes and the introduction of advanced technologies, with the use of high-performance equipment, in particular, valve converters, welding plants, powerful metalworking machines are being introduced. They are currently controlled using digital technology, these devices strictly impose high demands on the quality of electrical energy.In connection with the requirements of the quality of electricity, in the Russian Federation every 10-15 years new standards are developed, where the indicators of the quality of electric energy are normalized

The method of extending drone piloting autonomy when monitoring the technical condition of 6-10 kV overhead power lines

The paper considers options for the implementation of the technical condition monitoring of the of power supply system elements, the assessment of overgrowing of the power line routes using an unmanned aerial vehicle. A method for emergency control of an unmanned aerial vehicle used to monitor the technical condition of 6-10 kV overhead power lines has been proposed. This method is used in case of loss of radio communication between the unmanned aerial vehicle and the ground control station. The method is based on the activation of the automatic piloting system allowing the unmanned aerial vehicle flight to continue to the pre-determined emergency landing area. The autopilot is carried out by means of a servo controller and sensitive sensors reacting to the intensity of the electromagnetic field of a 6-10 kV overhead power line.

Использование солнечной батареи в составе системы электропитания космического разгонного блока

A storage battery is routinely used in the existing boosters equipped with liquid-fuel rocket engines. Under certain conditions, the electric power supply system mass can be essentially decreased by using a storage battery in combination with a photovoltaic array. The article considers the possibilities of using, in the composition of the space booster (SB) power supply system (PSS), a photovoltaic array (PVA) in addition to a storage battery with the aim to decrease the PSS mass. A procedure for selecting the optimal storage battery and photovoltaic array characteristics ensuring the minimal PSS mass has been determined, and the values of these characteristics have been estimated taking as an example an SB intended for placing a payload in a geostationary orbit. The obtained results may find use in substantiating the characteristics and developing PSS elements for prospective boosters.

Optimization model of power supply system of industrial enterprise

In this paper, the problem of optimizing the generated reactive power distribution for reducing the loss of active power in the elements of industry power supply system presented. The problem of optimal distribution of generated reactive powers by synchronous motors in the power supply systems belongs to the nonlinear mathematical programming class and can be solved by using the Lagrange multiplier method. The Lagrange method allows one to reduce the problem of conditional optimization (that is, finding the relative extremum of the objective function with certain limitations) to the simpler problem of unconditional optimization (the search of an absolute extremum).A complete mathematical model of optimization problem of the rational distribution of the generated reactive power by the synchronous motors in order to reduce the loss of active power in the power supply system elements of an industrial enterprise developed. The obtained mathematical problem allows one to consider a number of limitations related to both the mode of operation for the individual power supply system elements and the entire system as it is.

METHODS AND MEANS OF TECHNICAL LOSSES REDUCTION OF ELECTRICITY IN THE ELEMENTS OF POWER SUPPLY SYSTEMS

The aim of the work is to determine the factors that influence the change of electricity technical losses and the dynamics of power losses change depending on the exploitation term of the elements of power supply systems. This will allow to develop more accurate methods for determining the electric energy losses and calculate the real value of the power losses in the elements of the power supply system that have been operated for a long time. The task of electricity losses reduction is an important part of the more general problem of reducing energy consumption and efficient use of energy resources through the optimization of consumption and power generation.In the context of continuous growth of power rates and change of energy consumption, the energy saving and rational management of the power economy get the great importance and present not only engineering problem, but also the economic problem. Hence the need to reduce non-productive energy losses and improve the technical operation of power supply system appears. Currently, much attention is paid to the electric energy losses reduction through the development of more accurate methods of the energy losses determination in all elements of power systems.The analysis shows that the change of power losses is determined by changing of the permanent electric networks reconfiguration as a result of their reconstruction and changes in the conditions and frequency of use, as well as the technical state of the elements of power supply systems during the operation

Use of an analytical method for calculating reliability of elements of electric power systems based on probabilistic models

Today, we no longer have to prove the need for numerical evaluation of reliability of in-plant power supply systems. There have been established generally accepted reliability indices in the form of frequency of various accidents and mathematical expectation of undersupply of electricity to consumers, or decrease of power generation by plants. Factors are revealed factors that must be considered at analysis of reliability of power supply systems: availability of repair of switching circuits and duration of repair of the main equipment and switching equipment, failures of switching devices and devices of relay protection and automatics, routine switching, seasonal variations in damage to overhead lines and outdoor equipment. Here, one should take into account a possible lack of reliable initial information about the reliability of elements at the consideration of a specific installation. The paper formulates models of the analytical method of calculation of reliability parameters of elements of power supply systems in the Matlab software. Reliability models are considered for power units, which involve restoration and prevention activities. Three states of a system are considered: operable state; emergency downtime and recovery, scheduled downtime for preventive maintenance or repair subject to intensities of emergency and planned outages, intensities, recovery and completion of scheduled maintenance and repair. It is shown that, at present, targeted screening and quantification of contributions to unreliability of power supply systems by failures of elements of the system, its states and modes, as well as effectiveness of various measures, allow to identify weak links of the power supply systems and to work out specific ways for improvement in the process of human-machine synthesis of the power supply system. This approach to design involves searching for new circuit solutions, and changes in the structure of the circuit and layout solutions of its equipment mitigation of weaknesses, elimination of excessive equipment, or, on the contrary, using more reliable equipment, as well as its modernization.

Mathematical model of the standalone electrical supply system with distributed photoelectric generation

A promising way to increase the technical and economic characteristics of standalone power supply systems is to incorporate renewable energy installations in their structure. Photoelectric generators based on distributed sources are optimal technologies for the use of renewable energy sources in 0.4 kV low-voltage power grid. The most common option is a hybrid system with photoelectric power stations (PES) incorporated into the local network of the diesel power station (DPS). Photoelectric stations meet all environmental requirements and can make a significant contribution to the electrification of remote settlements, tourist and agricultural field. This paper deals with stabilization of voltage value and reduction of losses of electric energy depending on the parameters of elements of power supply systems of radial type (0,4 kV) with an installed capacity of up to 100 kW. The research has been conducted by simulating the operating modes of hybrid power systems of various configurations. To analyze the joint work of a photoelectric station with a diesel power station, a mathematical model is created in the Simulink (SimPowerSystems) application of the MatLab R2016b program. Most of the known works do not show the issues of quality and power losses in the standalone power supply system with photoelectric distributed generation. [5,6,7,9,10].