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Let H be a graph with vertex set V (H) = { v 1 , v 2 , ... , v k }. The generalized join graph H [ G 1 , G 2 , ... , G k ] is obtained from H by replacing each vertex v i with a graph G i and joining each vertex in G i with each vertex in G j provided v i v j ∈ E (H). If every G i is an independent set of n i vertices, then we write H [ G 1 , G 2 , ... , G k ] as H [ n 1 , n 2 , ... , n k ] , which is called the blow-up of H. In this paper we introduce the local complement transformation in electrical networks and obtain an electrically equivalent graph of H [ n 1 , n 2 , ... , n k ]. As their applications, we obtain formulae for resistance distances of some vertex-weighted graphs and give a unified technique to compute resistance distances in H [ G 1 , G 2 , ... , G k ] when every G i for 1 ≤ i ≤ k is a graph consisting of a matching and isolated vertices, which results in closed formulae for resistance distances of H [ G 1 , G 2 , ... , G k ] when H are some given graphs. [ABSTRACT FROM AUTHOR]

Space weather (SpW) is a phenomenon caused by a variety of solar events and has the potential to disrupt infrastructure systems and technology, putting them at risk. Despite SpW's immense impact, there has been a notable absence of bibliometric analysis studies to understand the research trends, regional distribution, social structure, conceptual structure, and knowledge gaps. This review synthesized scopus documents of SpW domain from 1988 to 2021. In this study, three tools were used, such as Microsoft Excel, VOSviewer, and Harzing's Publish or Perish for statistical analysis, graphical presentation, and citation metrics, respectively. Based on the 3,956 articles, roughly 70% of the articles were published in the last ten years, reveals a rapid growth in SpW research. The study discovered that China ranked third in publication volume, following the United States and the United Kingdom with Russian Federation following closely in fourth place. This study also presents six key findings, including the growth pattern of publications, contributions, and authorship collaboration by countries, most productive and influenced authors, co-authorship status, most influenced journals and articles, research cluster and new SpW subtopics discovered. These findings provide useful insight and aid in the advancement and progress of this field. [ABSTRACT FROM AUTHOR]

In order to maintain the technical leadership of the economic sector in any nation, there is currently a greater focus on guaranteeing the fail-safe operation of electrical networks and electrical equipment. This paper presents a model for evaluating the fault location procedure based on computer simulation in MATLAB/Simulink of complex 6(10)-35 kV power line systems. The proposed algorithm for preprocessing electrical network signals in normal and emergency modes uses a negative statistical correlation of all possible electrical parameters, while the resulting percentage errors when estimating the location of the fault are within acceptable limits. Algorithms and significant parameters have been determined for effectively carrying out the procedure for searching for the location of a fault through the use of modeling programs, namely: zerosequence voltage, negative-sequence voltage, initial current value. and the positive sequence voltage is the transition resistance at the accident site. An assessment of the results of preliminary modeling may indicate that devices for finding the location of a fault in the 6(10)-35 kV electrical network will be able to use information obtained about the object using the developed methodology, adjust calculation algorithms and take into account the operating modes of the electrical network. [ABSTRACT FROM AUTHOR]

Eaton (1992) considered a general parametric statistical model paired with an improper prior distribution for the parameter and proved that if a certain Markov chain, constructed using the model and the prior, is recurrent, then the improper prior is strongly admissible , which (roughly speaking) means that the generalized Bayes estimators derived from the corresponding posterior distribution are admissible. Hobert and Robert (1999) proved that Eaton's Markov chain is recurrent if and only if its so-called conjugate Markov chain is recurrent. The focus of this paper is a family of Markov chains that contains all of the conjugate chains that arise in the context of a Poisson model paired with an arbitrary improper prior for the mean parameter. Sufficient conditions for recurrence and transience are developed and these are used to establish new results concerning the strong admissibility of non-conjugate improper priors for the Poisson mean. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Arts & Social Sciences (JASS) is the property of Sultan Qaboos University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

RELEVANCE. Thermal imaging control is used to monitor the technical condition of electrical equipment, as well as contacts and contact connections of switching devices, which allows to increase the efficiency of work.OBJECT. Timely detection of defects of contacts and contact connections of low-voltage switching devices to prevent emergencies.METHODS. Determination and control of technical condition of electrical equipment, contacts and contact connections of apparatuses in real time by means of indicators and thermal imaging control.RESULTS. The values of contact heating temperatures from material and type of contact connections were analysed. The criteria for estimation of the state of contacts of switching devices with the help of indicators of their state have been determined. The optimum values of loading coefficients of the circuit breaker in moulded case VA04 and contactors KMI and KTI are obtained. Emergency cases at the industrial object are shown, which prove the necessity of application of indicators and thermal imaging control as one of the tools of automation of technical condition control of low-voltage electrical equipment.CONCLUSIONS. The offered noncontact method of estimation and control of technical condition of electrical equipment, contacts and contact connections of devices in real time with the help of indicators and thermal imaging control allows both to receive data in real time mode and to increase inter-repair periods for power equipment and to increase reliability of operation of the whole system.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.

A study of ways to modernize the current-conducting part of overhead lines was conducted in order to increase the efficiency of electric energy transmission. A comparative analysis of technical and economic characteristics of АS, ACCR, AERO-Z wires was performed. According to the results of the comparison of AS, ACCR, AERO-Z wires, it follows that the factor that limits the scope of application of ACCR wire in Ukrainian electrical networks, even for spans with extremely high requirements for the characteristics of electrical energy transmission, is its high cost. Also, during the research, it was found that the AERO-Z wire is the most appropriate for introduction into Ukrainian electrical networks. Because the technical characteristics of this wire are better than the characteristics of AS wire and it has a relatively low cost compared to ACCR wire, and its special design is adapted to adverse climatic conditions that affect the characteristics of electrical energy transmission. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic model based on neutrosophic numbers and a neutrosophic logic engine. The introduced neutrosophic logic/fuzzy adaptive Zeroing Neural Network dynamic is termed NSFZNN and represents an improvement over the traditional Zeroing Neural Network (ZNN) design. The model aims to calculate the matrix pseudo-inverse and the minimum-norm least-squares solutions of time-varying linear systems. The improvement of the proposed model emerges from the advantages of neutrosophic logic over fuzzy and intuitionistic fuzzy logic in solving complex problems associated with predictions, vagueness, uncertainty, and imprecision. We use neutrosphication, de-fuzzification, and de-neutrosophication instead of fuzzification and de-fuzzification exploited so far. The basic idea is based on the known advantages of neutrosophic systems compared to fuzzy systems. Simulation examples and engineering applications on localization problems and electrical networks are presented to test the efficiency and accuracy of the proposed dynamical system. [ABSTRACT FROM AUTHOR]

The operational cost of a microgrid is significantly influenced by the response of storage systems and the complexities of the power market's tariff structures. This paper addresses the challenges arising from the coexistence of new market entries and traditional tariffs, which contribute to a complex market environment. To tackle this issue, the paper establishes a microgrid market environment encompassing four types of tariffs. By modeling the response of electric storage and cold storage in a microgrid, the study formulates a non-linear mixed-integer optimization problem. Numerical studies are then conducted to verify the model and analyze market performance. The results reveal a trade-off in behavior among different market entries when optimizing the total cost of microgrid operation. These findings shed light on the complexities and tradeoffs involved in microgrid operational cost optimization within a diverse market environment, offering valuable insights for market participants. [ABSTRACT FROM AUTHOR]

The article presents an analysis of electromagnetic transient processes in long ultra-high voltage transmission lines, taking into account shield wires. It was shown that EMTP and Matlab/Simulink software are currently widely used in the study of transient processes in power lines. The EMTP software package uses the finite element method when integrating the equation that mathematically models the distributed parameter transmission line. The Matlab/Simulink software uses the d'Alembert method. In both cases, it is not known how the boundary conditions for the partial differential equation that mathematically models the transmission line are determined. The power line is analyzed as a distributed parameter system, described by a second-order partial differential equation. The advantage of the proposed method of calculating the boundary conditions for the abovementioned equation is the use of boundary conditions of the second and third types of Neumann and Poincaré, which allowed us to take into account the mutual influence of shield wires and phase conductors of the line in one power system. On this basis, the methodology for obtaining time domain graphs, spatial distributions, and traveling wave distributions of voltages and currents for phase conductors and line shielding wires is presented. The results of a computer simulation of transient processes when switching on the power line, taking into account controlled phase commutation and under single-phase earth fault conditions, are presented. All calculation results of transient processes presented in the article were obtained exclusively using numerical methods. [ABSTRACT FROM AUTHOR]

The concept of forming an objective function for solving the problem of the quality of electrical energy optimizing in power networks is proposed, which takes into account the uncertainty factor of information about the mode parameters. This will allow, in contrast to the traditional binary function of assessing the quality of electrical energy for compliance with the established standards, to take into account the dynamics of changes in the efficiency criterion and perform the search for optimal values of the relevant controlling influences. The classification of information flows about the mode of the electric network is presented and the boundaries of fuzzy set for the values of the mode parameters are defined. It is shown that the objective function should be appropriately formed on the basis of fuzzy logic. The principles of the formation of fuzzy mathematical models for the analysis of established normal modes of the electrical network are defined. It is proposed to determine the membership function of a fuzzy set taking into account the quality of information that can be provided by the technical means of the electrical network. Ref. 5, fig. 3.

The article presents algorithms for optimizing the configuration of distribution electric grids according to the criterion of minimum losses of active power and reliability indicators, taking into account the limitations: the maximum permissible deviation of the voltage in the load nodes and the maximum permissible value of the current in the power transmission lines. The optimization algorithm of a separate feeder based on the minimum active power loss criterion, which is based on the sensitivity analysis of the reduction of active power losses or electricity losses, is considered. The optimization procedure, which consists in closing the chord and opening the branch of the tree, is based on choosing to open the most distant branch that is included in this independent circuit (the chord and the branch that is opened are located on the branches that are connected to the same node). The initial orientation when selecting branches for opening is based on the calculation of the closed grid. Branches with relatively small currents are defined as potentially optimal for opening. To automatically determine the structure of the feeder tree, a matrix of contours is used, which are represented by a list of branches included in the contours. The exchange of branches is carried out according to the affiliation of chords and branches potentially optimal for opening to the same circuits. Since 10 kV distribution grids, as a rule, function as radial grids with installed open line disconnectors for redundant connection of feeders to each other, this algorithm can be applied to optimize a group of feeders. The paper presents the optimization algorithm of several feeders on the example of Khmelnytskyi REM according to the criterion of minimum electricity losses and indicators of reliability of electricity supply to consumers. The optimization algorithm of several feeders is based on the optimization algorithm of a single feeder, supplemented by a check of restrictions on the maximum values of voltage losses in load nodes and maximum load currents of power transmission lines. [ABSTRACT FROM AUTHOR]

The overhead electrical power lines, which are part of the electricity distribution network, could be considerable threat to different bird species. The main incidents are related to electrocution and bird`s collision with power lines. The biggest danger comes from electrocution – in these cases birds die as a result of contact with the power line. The electrical current generates electric arc through the bird and the power line and leading to the birds’ instant death. The Green Balkans, as а breeder in SPA Sakar BG 002021 Bulgaria, and under the projects “Lesser Kestrel Recovery” LIFE11 NAT/BG/360 and “LIFE for Lesser Kestrel” LIFE19 NAT/BG/001017 succeeded to recover Lesser Kestrel (Falco naumanni, Fleischer 1818) and among the aims of the project was to take measures to mitigate the threat of electrocution. Among the operational over ground power grid lines in Bulgaria, according to the electrical voltage, the most dangerous and life threatening to birds is the mid voltage power supply grid (20 kV) that is also the main cause for death from electrocution. The Green Balkans` team conducted field research of the dangerous types of pylons, on-site isolation of electricity pylons has been identified within a range of 4.5 km of the Lesser Kestrel colony. According to the way of safeguarding the elements of the electrical grid several different devices were used: “Rigid bird protective cover”, perch guards and bird discouragers. Safeguarding by installation of perches has also been done. The isolation of dangerous pylons in the electrical network ensured safe conditions not only for the Lesser Kestrels, but also for other birds that use the power line elements as landing sites, rest spots, or even for nesting. [ABSTRACT FROM AUTHOR]

This paper deals with the reduction in electrical losses and the minimization of voltage deviation in electrical power grids. To this end, a novel heuristic-based approach is proposed for controlling reactive power injections along an electrical grid with distributed generation using distributed photovoltaic (PV) generation. The proposed approach consists of applying a heuristic, namely a genetic or firefly algorithm, to solve the loss and voltage deviation optimization problem by controlling PV reactive power injections. The proposed method was tested on a radial 100-bus network with an intense penetration of PV generation. The obtained results indicate that the proposed method consistently yields superior grid performance when compared to algorithms previously proposed in the literature. In fact, it led to a reduction in the active power supplied by the reference bus to the grid, thereby alleviating the burden imposed on the most upstream parts of the distribution network. As a consequence, the proposed method contributes to a power-efficient network, enhancing its loss performance and voltage stability. [ABSTRACT FROM AUTHOR]

The article is devoted to the investigation of reactive power compensation modes in a closed electrical network, which is significantly loaded with active-inductive elements in the nodes of electricity consumption. The initial mode without compensation is compared with the modes of partial and full compensation of reactive power using capacitor compensation banks. It is shown how to determine this mode using search optimization using a visual model of the electrical network. Quantitative indicators of the compared modes are presented, which convincingly demonstrate the advantages of full reactive power compensation in the electrical network. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main objective of this paper is to develop the concepts and ideas used in the theory of weighted networks on infinite graphs. Our basic ingredients are a standard Borel space (V , B) and symmetric σ -finite measure ρ on (V × V , B × B) supported by a symmetric Borel subset E ⊂ V × V . This setting is analogous to that of weighted networks and are used in various areas of mathematics such as Dirichlet forms, graphons, Borel equivalence relations, Guassian processes, determinantal point processes, joinings, etc. We define and study the properties of a measurable analogue of the graph Laplacian, finite energy Hilbert space, dissipation Hilbert space, and reversible Markov processes associated directly with the measurable framework. In the settings of networks on infinite graphs and standard Borel space, our present focus will be on the following two dichotomies: (i) Discrete vs continuous (or rather the measurable category); and (ii) deterministic vs stochastic. Both (i) and (ii) will be made precise inside our paper; in fact, this part constitutes a separate issue of independent interest. A main question we shall address in connection with both (i) and (ii) is that of limits. For example, what are the useful notions, and results, which yield measurable limits; more precisely, Borel structures arising as “limits” of systems of graph networks? We shall study it both in the abstract, and via concrete examples, especially models built on Bratteli diagrams. The question of limits is of basic interest; both as part of the study of dynamical systems on path- space; and also with regards to numerical considerations; and design of simulations. The particular contexts for the study of this question entails a careful design of appropriate Hilbert spaces, as well as operators acting between them. Our main results include: an explicit spectral theory for measure theoretic graph-Laplace operators; new properties of Green’s functions and corresponding reproducing kernel Hilbert spaces; structure theorems of the set of harmonic functions in L 2 -spaces and finite energy Hilbert spaces; the theory of reproducing kernel Hilbert spaces related to Laplace operators; a rigorous analysis of the Laplacian on Borel equivalence relations; a new decomposition theory; irreducibility criteria; dynamical systems governed by endomorphisms and measurable fields; and path-space measures and induced dissipation Hilbert spaces. We discuss also several applications of our results to other fields such as machine learning problems, ergodic theory, and reproducing kernel Hilbert spaces. [ABSTRACT FROM AUTHOR]

The operational cost of a microgrid is significantly influenced by the response of storage systems and the complexities of the power market’s tariff structures. This paper addresses the challenges arising from the coexistence of new market entries and traditional tariffs, which contribute to a complex market environment. To tackle this issue, the paper establishes a microgrid market environment encompassing four types of tariffs. By modeling the response of electric storage and cold storage in a microgrid, the study formulates a non-linear mixed-integer optimization problem. Numerical studies are then conducted to verify the model and analyze market performance. The results reveal a trade-off in behavior among different market entries when optimizing the total cost of microgrid operation. These findings shed light on the complexities and trade-offs involved in microgrid operational cost optimization within a diverse market environment, offering valuable insights for market participants.

Realizing a lithium sulfide (Li2S) cathode with both high energy density and a long lifespan requires an innovative cathode design that maximizes electrochemical performance and resists electrode deterioration. Herein, a high‐loading Li2S‐based cathode with micrometric Li2S particles composed of two‐dimensional graphene (Gr) and one‐dimensional carbon nanotubes (CNTs) in a compact geometry is developed, and the role of CNTs in stable cycling of high‐capacity Li–S batteries is emphasized. In a dimensionally combined carbon matrix, CNTs embedded within the Gr sheets create robust and sustainable electron diffusion pathways while suppressing the passivation of the active carbon surface. As a unique point, during the first charging process, the proposed cathode is fully activated through the direct conversion of Li2S into S8 without inducing lithium polysulfide formation. The direct conversion of Li2S into S8 in the composite cathode is ubiquitously investigated using the combined study of in situ Raman spectroscopy, in situ optical microscopy, and cryogenic transmission electron microscopy. The composite cathode demonstrates unprecedented electrochemical properties even with a high Li2S loading of 10 mg cm–2; in particular, the practical and safe Li–S full cell coupled with a graphite anode shows ultra‐long‐term cycling stability over 800 cycles. [ABSTRACT FROM AUTHOR]

The cover time of random walks on a graph has found wide practical applications in different fields of computer science, such as crawling and searching on the World Wide Web and query processing in sensor networks, with the application effects dependent on the behavior of the cover time: the smaller the cover time, the better the application performance. It was proved that over all graphs with N nodes, complete graphs have the minimum cover time N log N. However, complete graphs cannot mimic real-world networks with small average degree and scale-free small-world properties, for which the cover time has not been examined carefully, and its behavior is still not well understood. In this article, we first experimentally evaluate the cover time for various real-world networks with scale-free small-world properties, which scales as N log N. To better understand the behavior of the cover time for real-world networks, we then study the cover time of three scale-free small-world model networks by using the connection between cover time and resistance diameter. For all the three networks, their cover time also behaves as N log N. This work indicates that sparse networks with scale-free and small-world topology are favorable architectures with optimal scaling of cover time. Our results deepen understanding the behavior of cover time in real-world networks with scale-free small-world structure, and have potential implications in the design of efficient algorithms related to cover time. [ABSTRACT FROM AUTHOR]

Electrical energy is transmitted through the electrical network from power generating station to the consumers. For this purpose, the overhead transmission line is used through which bulk power can be transferred. The conventional electrical network transmits the energy with power loss. The reason for the power loss is due to inherent characteristic of the transmission line and corona discharge which affects the performance of the transmission line. In this work, performance analysis of overhead transmission line is analyzed by developed MATLAB code and tested for different weather (fair and stormy) conditions by using peek's formula. [ABSTRACT FROM AUTHOR]

The paper considers the task of creating an instrumental system for optimizing the exchange of active power of the trunk and distribution networks, taking into account the price indicators of electricity in a joint and separate mode of operation. As part of the development of a simulation model of the automated control system of the local intelligent power system MicroGrid, the results of modeling the exchange of active power of the power connection from the main network of the main South of Russia main electrical networks and the distribution network of the university campus (in which classical sources of generation are combined with solar, wind and hydrogen energy) are presented. In a single model, the electrical mode of operation of networks is simulated in the voltage range of 0.4–500 kV. Simulation is carried out in steady state and transient mode. Slow, real and fast time modes are available. Simulation of emergency control systems has been implemented. The modes of synchronization of the main and distribution networks in normal and emergency circuits are considered. Reliability control and monitoring of the main operating parameters are carried out. The active power exchange module created on the basis of the results of the simulation as part of the software package « RETREN » will make it possible to use this complex to automate the management of local power system. The energy system, in addition to power from the grid, includes gas generation, solar panels installed on the roofs of campus buildings, wind turbines and stationary hydrogen power plants operating on hydrogen fuel cells. The complex of designers allows organizing human-machine interfaces of any complexity on completely domestic software products. [ABSTRACT FROM AUTHOR]

Abstract Realizing a lithium sulfide (Li2S) cathode with both high energy density and a long lifespan requires an innovative cathode design that maximizes electrochemical performance and resists electrode deterioration. Herein, a high‐loading Li2S‐based cathode with micrometric Li2S particles composed of two‐dimensional graphene (Gr) and one‐dimensional carbon nanotubes (CNTs) in a compact geometry is developed, and the role of CNTs in stable cycling of high‐capacity Li–S batteries is emphasized. In a dimensionally combined carbon matrix, CNTs embedded within the Gr sheets create robust and sustainable electron diffusion pathways while suppressing the passivation of the active carbon surface. As a unique point, during the first charging process, the proposed cathode is fully activated through the direct conversion of Li2S into S8 without inducing lithium polysulfide formation. The direct conversion of Li2S into S8 in the composite cathode is ubiquitously investigated using the combined study of in situ Raman spectroscopy, in situ optical microscopy, and cryogenic transmission electron microscopy. The composite cathode demonstrates unprecedented electrochemical properties even with a high Li2S loading of 10 mg cm–2; in particular, the practical and safe Li–S full cell coupled with a graphite anode shows ultra‐long‐term cycling stability over 800 cycles.

Calculations of steady-state modes of a complex electric power system are significantly simplified if we use the coefficients of distribution of the setting currents. The use of the theory of directed graphs for the formation of the matrix of the coefficients of distribution of the setting currents is directly related to the determination of the values of all possible and specific trees of the graph of a complex electric network. The authors have developed and implemented an improved algorithm. calculation of current distribution coefficients of the electric power system. The concepts of the “base” of the graph and the “hanging” contour are introduced. In this case, to calculate the current distribution coefficients, it is necessary to take into account all possible and specific trees of only the graph base. A method is indicated for supplementing the matrix of current distribution coefficients of the graph base to the current distribution matrix of the original graph. The paper proposes methods for simplifying the network topology based on the development of diacoptic principles.

The article considers the possibility of determining the source of higher harmonics of currents and voltages in the electrical network in the directions of power of the respective components. The research purpose is evaluating the effectiveness of theoretical methods, computer modeling of a fragment of the electrical network and electrical load receivers operating in parallel. Different combinations of active, reactive and nonlinear loading are investigated. Larionov's scheme was used as a nonlinear load. According to the results of the study, conclusions were made about the effectiveness of the method used. Thus, in particular, in the case of parallel operation of nonlinear and mixed active-nonlinear load, the source of higher harmonics is determined incorrectly. Suggestions for ways to improve the algorithm are made.

Photovoltaic (PV) systems have been rapidly implemented in commercial facilities without determining the negative impacts that may result when connected to the facilities' electrical power system. The research presented shows the results of a study of the quality of electrical energy in a commercial installation in which there were no problems before implementing the PV system. Measurements of different parameters of the energy generated by the photovoltaic system and that provided by the electrical network are carried out, carrying out a simulation using the Helioscope software. As a result of the work, voltage variation and current harmonics problems are identified, carrying out a technical and economic analysis of implementing a passive filter that performs the respective corrective actions.

One possible device authentication method is based on device fingerprints, such as software- or hardware-based unique characteristics. In this paper, we propose a fingerprinting technique based on passive externally measured information, i.e., current consumption from the electrical network. The key insight is that small hardware discrepancies naturally exist even between same-electrical-circuit devices, making it feasible to identify slight variations in the consumed current under steady-state conditions. An experimental database of current consumption signals of two similar groups containing 20 same-model computer displays was collected. The resulting signals were classified using various state-of-the-art time-series classification (TSC) methods. We successfully identified 40 similar (same-model) electrical devices with about 94% precision, while most errors were concentrated in confusion between a small number of devices. A simplified empirical wavelet transform (EWT) paired with a linear discriminant analysis (LDA) classifier was shown to be the recommended classification method. [ABSTRACT FROM AUTHOR]

The mathematical model of a fragment of a high-voltage electric network is developed in this paper. The network consists of a long power line with distributed parameters and an equivalent three-phase active-inductive load. Neumann and Robin—Poincare boundary conditions were used to identify the boundary conditions for the long line equation. The parameter output voltage (voltage at the end of the line) is introduced into the paper for further universal use of the developed line model. On the basis of the developed mathematical model, the program code is written in the algorithmic language Visual Fortran. By means of it, oscillograms of transient electromagnetic processes of voltages and currents in the form of spatial, temporal and temporal-spatial distributions during remote two-phase short circuits in the transmission line of high voltage are obtained. Two transient electromagnetic processes are analyzed in the present work. The first one was analyzed during the switching on of the line to the normal mode of operation with the subsequent transition to the emergency mode. The second one was analyzed during the switching on the line in the mode of a remote two-phase short circuit to the ground. The results of transient electromagnetic process simulation in the form of analyzed figures are shown. All the results presented in this paper were obtained exclusively using numerical methods. [ABSTRACT FROM AUTHOR]

The problem of calculating the power flows and wire temperature of the supply network in the steady state mode of a power system is examined. The topology and parameters of the network, and consumption and generation, are presupposed, as well as weather factors affecting the power lines: ambient temperature, solar radiation, and wind direction and speed. Analysis was done of the previously proposed algorithms for solving this problem, which are based on taking into account the temperature dependence of active line resistances. The shortcomings of these algorithms are shown, and a new method of calculating the node voltages that characterize the active resistances and the temperature of the line wires, and power flows in the steady state of the power system. The proposed approach is based on taking into account the influence of node voltages on the active resistances of the wires and the currents of network lines. Computational experiments demonstrate the correctness of the proposed calculation expressions. The results of comparison with the calculated data obtained by the previously considered algorithms are presented. The proposed method can be used to assess the impact of weather factors on the steady state parameters, which are necessary for system operators in the analysis of actual and future schemes of development of electric networks, including taking into account renewable sources of energy (RSE) and distributed generation. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents aspects regarding the construction and operation of hybrid plants consisting of renewable energy sources, electrolyzes and hydrogen and electricity storage facilities that have been obtained. The authors analyze the energy processes in hydrogen production stations in order to optimize operating costs. The cheap electricity obtained for example through photovoltaic panels, can supply the electrolysis stations and the resulting hydrogen in this case, will have low production costs without negative ecological impact. At the end of paper are stated some conclusions that resulted from the study.

The study results of overvoltages during arc single-phase earth faults of intermittent nature in the 35 kV electric net-work with isolated neutral are presented. With the help of computer simulations of transients in the electrical network, the maximum multiplicities of overvoltages at the point of occurrence of single-phase arc earth faults have been ob-tained. According to known theories of the occurrence and development of overvoltages, it exceeds theoretically ex-pected. The change of the overvoltage level on the 35 kV busbars of the network substations, electrically connected to the place of occurrence of the single-phase earth fault, has been shown. The influence of the cable line on the overvolt-age multiplicity is shown. Ref. 12, fig. 3, table.

Any alternating electric power supply is always characterized by three reference quantities, which are voltage, electric power and frequency. The generators of power stations are synchronous machines. The present work is based on the modelling of the synchronous machine for a study of the stability of the electricity transmission network. The example considered is a thermal power station of the national network. i.e., Algiers port power station. We have developed a computer program based on MATLAB to simulate the calculations of our multi-variable system. The study presented in this article examines the static stability of a thermal power plant. To make this study a reality, it is necessary to model the synchronous machine. We present the three models of the synchronous machine by emphasizing the role of the shock absorbers and the smoothness of the model with three windings. This work is supported by a spectral analysis based on the eigenvalues of the system. [ABSTRACT FROM AUTHOR]

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The increase use of polluting equipment, especially in the field of power electronics, has caused appearance of harmonics and deterioration in the supplied current wave quality. For this reason, several harmonic pollution control methods have been developed, and the use of the active filtering presents the most efficient and appropriate solution. This work concerns improving energy quality of an electrical network by using an active parallel filter. To achieve this objective, three essential steps were pursued: identification of the harmonic currents, insertion and control of an active parallel filter, and checking effectiveness of the adopted filtering strategy by comparing the total harmonic distortion (THD) values before and after filtering. The various obtained results prove capacity of the inserted active filter to decontaminate harmonic pollution and consequently improve the energy quality. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm to optimize the deployment of hubs for smart energy metering based on the Internet of Things. A georeferenced scenario is proposed in which each user must connect to a concentrator, either directly or through another user, minimizing the resources required to achieve connectivity. Consequently, to carry out the optimization, the minimum spanning tree between devices is found, in which the maximum connection distance and the capacity of the hubs are limited. Additionally, this work seeks to achieve a scalable algorithm applicable to any georeferenced scenario to be simulated. The main contribution of this work is an IoT-based smart metering architecture that optimizes resources and adapts to a scenario that changes or integrates more users to the energy metering network without losing the connectivity of the initial users. As a result of the application of the algorithm, a scenario route map is generated. The scenario's parameters include the number of hops in the network, the optimal number of concentrators and their geographical location, the average number of hops, and the total distance of the path, among others. In this project, a georeferenced urban scenario was considered in which residential areas coexist with intelligent buildings. The scenario has growth stages in which the algorithm is applied, and in each one, the optimal route map is generated. [ABSTRACT FROM AUTHOR]

Smart Grid technology will revolutionize modern industries providing powerful solutions to increase the efficiency of traditional Electric Grids. Smart Grid is an energy supply network that uses digital communications technology. The increasing load and consumption demands increase electricity complications, for instance, the demand has increased, along with problems like blackouts, overloads, and voltage sags as well as current electrical network growing critical carbon emissions and foremost dealing with cyber-attacks. However, the Smart Grid technology originates with vulnerabilities and complications especially for securing information which is the most vital concern. This article analyzes the threats and potential solutions of smart grids based on the Internet of Things. We focus on the types of cyber attacks and provide in-depth information The cyber security status of the smart grid.

We calculate effective impedances of infinite LC- and CL-ladder networks as limits of effective impedances of finite network approximations, using a new method, which involves precise mathematical concepts. These concepts are related to the classical differential operators on weighted graphs. As an auxiliary result, we solve a discrete boundary value Dirichlet problem on a finite ladder network. [ABSTRACT FROM AUTHOR]

In this paper we deal with the notion of the effective impedance of alternating current (AC) networks consisting of resistances, coils and capacitors. Mathematically such a network is a locally finite graph whose edges are endowed with complex-valued weights depending on a complex parameter λ (by the physical meaning, λ = iω, where ω is the frequency of the AC). For finite networks, we prove some estimates of the effective impedance. Using these estimates, we show that, for infinite networks, the sequence of impedances of finite graph approximations converges in certain domains in ℂ to a holomorphic function of λ, which allows us to define the effective impedance of the infinite network. [ABSTRACT FROM AUTHOR]