Alexander Vinogradov

PURPOSE. Currently, modeling is one of the most reliable ways to study normal and emergency modes of operation of electrical networks. In this regard, a mathematical model of the 0.4 kV rural electric network was developed in the MATLAB Simulink program.PURPOSE. Evaluation of the accuracy of the parameters of the operating modes of the 0.4 kV rural electric network obtained by modeling in MATLAB Simulink by estimating the values of the steady-state single-phase short circuit current at different distances from the transformer substation.METHODS. The currents obtained using the 0.4 kV electrical network model developed in MATLAB Simulink were compared with the currents obtained using other calculation methods (according to GOST 28249-93, the simplified phase-zero loop method and the mathematical model «Project RZA»).RESULTS. It was revealed that the discrepancy in the results at individual points was 9-11%. When simulating a steady-state single-phase short circuit in MATLAB Simulink, it was found that the voltage of the damaged phase A decreases to 0 V, while the voltages on the two remaining intact phases increase by 1.4-1.5 times, i.e.E. by a factor of 2 to the values of 335-354 V when short-circuiting at the transformer terminals and to the values of 329-338 V when short-circuiting behind a section of a 0.4 kV power line.CONCLUSIONS. The resulting mathematical model of a 0.4 kV rural electric network in the MATLAB Simulink program can be used to study normal and emergency operating modes, study the modes of joint operation of renewable energy sources with a centralized network, and the processes of switching on backup generation sources.

Electricity supply as well as the provision of other forms of resources is one of the foundations of efficient agriculture. However, due to the reduction in the number of people living in rural settlements, there have been a large number of power lines with considerable lengths supplying small loads, hence resulting in an increase in power supply efficiency. A single-wire power transmission is an option for reducing the capital cost of power line construction by utilizing fewer conductors and fittings and lighter power transmission towers while lowering operational expenses. This paper considers the possible methods for single-wire energy transmission via the analysis of information sources such as Yandex and Google search engines; Scopus and Google Scholar scientific databases; and Cyber Leninka, eLIBRARY.ru, Elsevier, Springer, IEEE Xplore, and IGI Global electronic libraries. The conducted review revealed four alternatives: a single-wire earth return (SWER) system, a single-wire balanced line (B-Line), resonant wireless power transmission (SWPT) system, and a resonant single-wire power transmission system. The latter is of particular interest due to the lack of comprehensive and detailed information describing this technology, although it has distinct characteristics because of the peculiarities of the resonant mode of operation. The paper provides a comprehensive review of all existing published materials on the topic of “resonant systems for the transmission of electrical energy along a single wire”. The study covers the history of development and the structure of this system; describes its features, advantages, and the problems of using it; and the experience and fields of its application.

Electrotechnical services spend a significant amount of time on cable tracing and conductor identification operations. Although the operation of conductor identification seems an easy job and a deeply researched topic, it may turn out to be time-consuming due to the large quantity of unidentified conductors (cables) and the certain stipulation that conductors should be de-energized and have uninsulated parts. This paper proposes a method based on the use of an acoustic signal as a carrier, making it possible to facilitate the identification process and significantly speed up the identification process. For the proposed method, mathematical modeling of the sound propagation in conductors and insulation is detailed. The sound pressure level subject to identified conductor length, conductor cross-section and insulation type was calculated on the basis of the model. The performed calculations revealed remarkable capabilities of the acoustic method for identifying conductors in comparison with other methods. So, the difference in sound pressure level is only 3.65% for distances from the identification point to the signal source of 5 m and 100 m, 0.42% between the minimum and maximum cross sections of conductors (1 mm² and 25 mm², respectively) and 0.22% between conductors with polyethylene and PVC insulations. The prototype of conductor identification device was assembled in a way that practically confirmed the theoretical research with the average percentage of discrepancy of about 1.44%. In addition, the paper analyzes the conductor identification operation constituents to justify the application of the acoustic method by comparison with other identification methods.

The author offers a power-efficient multichannel low-pass filter for digital image processing based on the cascade multiple accumulate finite impulse response (CMFIR) structure in this study. The CMFIR filter was created using the outputs of a linear time-invariant system (LTI), which was built using a cascaded integrator comb (CIC) and a MAC low-pass filter. The sample rate convertor based on CIC filters effectively conducts decimation or interpolation. The sample rate convertor with the CIC filter can only accommodate narrowband transmissions and so cannot be utilized for wideband signals. The MAC architecture-based sample rate convertor is a good solution for high-bandwidth signals, but it uses more resources like registers and flip-flops, which increases power consumption. Here, the CMFIR low-pass filter acts as an interpolator, introducing a sample to boost the image's resolution. CMFIR is a useful tool for addressing the issue of aliasing during sampling. In addition, the genetic algorithm was used to increase the filter's resource utilization and power consumption efficiency.

Sectionalizing 0.4 kV power transmission lines (PTL) improves power supply reliability and reduces electricity undersupply through the prevention of energy disconnection of consumers in the event of a short circuit in the power line behind the sectionalizing unit (SU). This research examines the impact of sectionalizing on power supply reliability and reviews the literature on sectionalizing unit allocation strategies in electrical networks. This paper describes the experience of the use of sectionalizing units with listing strengths and weaknesses of adopted technical solutions and describes the new structure of sectionalizing units. A new methodology is proposed, whereby there are two criteria for allocating SU in 0.4 kV power transmission lines. The first criterion is the sensitivity limits against single-phase short circuits used for calculating the maximum distance at which SU can be installed. The second criterion is power supply reliability improvement, evaluating the cost-effectiveness of installing sectionalizing equipment by reducing power supply outage time. The established methodology was put to the test on an actual electrical system (Mezenka village, Orel area, Russia), which demonstrated that the installation of a sectionalizing unit paid off.

A significant disadvantage of rural distribution electric grids of 0.4 kV is the lack of the ability to operate their configuration. This disadvantage leads to a decrease in the reliability of electricity supply and significant damage to rural consumers from interruptions in electricity supply. A promising direction is the introduction of distributed generation based on renewable energy sources (RES), electricity storage devices into the structure of rural electric grids and the construction of microgrids based on them. However, the issues of building rural microgrids have not been worked out today, the search for rational options for their structure is being conducted all over the world, the development of equipment for their construction is underway. Therefore, the purpose of the research presented in the article is to determine the tasks and strategies for operating the configuration of rural microgrids containing renewable energy sources (RES) based on the use of means of partitioning and reserving the electric grid, that is, means of controlling its configuration and means of monitoring the parameters of its operation modes. As a means of partitioning and reserving the electric grid, it is proposed to use multi-contact switching systems installed at the points of branches in the grid and equipped with sensors for the parameters of the grid operating modes. The use of multi-contact switching systems allows you to implement a flexible change in the grid configuration when changing its operating modes. Power supply sources are also equipped with sensors. The data from the sensors is transmitted to the virtual power plant, which monitors the operating modes of the grid and forms commands for controlling its configuration. This allows you to monitor the operating modes of grid sections and power supply sources, identify normal, emergency and post-emergency modes and make the necessary changes to the grid configuration in a timely manner. As a strategy for the operation of an electrical grid containing renewable energy sources and configuration operating tools, a strategy is proposed that assumes the maximum use of the energy generated by renewable sources when the restrictions are met – a given level of reliability of power supply to consumers and the quality of electricity supplied to them

In recent times, Blockchain has emerged as a transformational technology with the ability to disrupt and evolve multiple domains. As a decentralized, immutable distributed ledger, Blockchain technology is one of the most recent entrants to the comprehensive ideology of Smart Cities. The rise of urbanization and increased citizen participation have led to various technology integrations in our present-day cities. For cities to become smart, we need standard frameworks and procedures for integrating technology, citizens and governments. In this paper, we explore the potential of Blockchain technology as an enabler for e-governance in smart cities. We examine the daily challenges of citizens and compare them with the benefits being offered by Blockchain integration. On the basis of a comprehensive literature review, we identified four key areas of e-governance wherein Blockchain can provide monumental advantages. In the context of Blockchain integration for e-governance, the paper presents a survey of prominent published works discussing various urban applications.

Nowadays, breast cancer is the most frequent cancer among women. Early detection is a critical issue that can be effectively achieved by machine learning (ML) techniques. Thus in this article, the methods to improve the accuracy of ML classification models for the prognosis of breast cancer are investigated. Wrapper-based feature selection approach along with nature-inspired algorithms such as Particle Swarm Optimization, Genetic Search, and Greedy Stepwise has been used to identify the important features. On these selected features popular machine learning classifiers Support Vector Machine, J48 (C4.5 Decision Tree Algorithm), Multilayer-Perceptron (a feed-forward ANN) were used in the system. The methodology of the proposed system is structured into five stages which include (1) Data Pre-processing; (2) Data imbalance handling; (3) Feature Selection; (4) Machine Learning Classifiers; (5) classifier’s performance evaluation. The dataset under this research experimentation is referred from the UCI Machine Learning Repository, named Breast Cancer Wisconsin (Diagnostic) Data Set. This article indicated that the J48 decision tree classifier is the appropriate machine learning-based classifier for optimum breast cancer prognosis. Support Vector Machine with Particle Swarm Optimization algorithm for feature selection achieves the accuracy of 98.24%, MCC = 0.961, Sensitivity = 99.11%, Specificity = 96.54%, and Kappa statistics of 0.9606. It is also observed that the J48 Decision Tree classifier with the Genetic Search algorithm for feature selection achieves the accuracy of 98.83%, MCC = 0.974, Sensitivity = 98.95%, Specificity = 98.58%, and Kappa statistics of 0.9735. Furthermore, Multilayer Perceptron ANN classifier with Genetic Search algorithm for feature selection achieves the accuracy of 98.59%, MCC = 0.968, Sensitivity = 98.6%, Specificity = 98.57%, and Kappa statistics of 0.9682.

The purpose of the work is to increase the protection efficiency of 0.4 kV power lines with branch lines from single-phase short circuits by means of using the multi-contact switching system MSS-2-3. It can be not possible to provide the necessary sensitivity of protecting 0.4 kV power lines against one-phase short circuits when the power line length is too high and when the wire cross section does not provide the necessary value of the phase-zero loop resistance. Power line sectionalizing helps to solve this problem. It allows dividing power lines into sections, each is protected by its protective device. The settings of the protective devices installed at the beginning of a power transmission line and at the sectioning units (SU) are different. It provides the necessary selectivity of their work. At the same time, many power transmission lines (PTL) have long branch lines. The choice of the installation site of SU in such lines is difficult since a short circuit or other damage can occur both on a trunk line section and on a branch line. When installing SU both before a branch line and behind it, there might be the cases of unjustified power supply outages. Therefore, it is necessary to develop devices allowing for sectionalizing such power lines at the installation site of SU while ensuring the possibility of disconnecting both a trunk line section and a branch line directly. Such a device is a multi-contact switching system having two independent contact groups and three outputs (MSS-2-3). Installing the MSS-2-3 at a branch line point increases the security of the power transmission line against short circuits including single-phase ones and also increases power supply reliability to consumers since only a damaged section is disconnected in case of damage to the power transmission line. The feature of choosing the settings for the operation of switching devices installed in the MKS-2-3 to protect the switched power line sections is the need to take into account the parameters of a trunk line section and a branch line