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Consider the propagation of electromagnetic energy through multiconductor three-phase high-voltage transmission line with arbitrary number of conductors. The mathematical formulation of the problem represents the system of partial differential equations known as transmission line equations. When constructing the capacitance matrix of an electric line, it is necessary to solve the boundary problems for the Laplace equation with nonlocal boundary conditions. The aim of this research is to develop a new method for constructing a potential coefficients matrix, which allows us to express the voltage vector in the wires through the charge vector. The application of this method leads to the necessity of solving a boundary value problem for Laplace equations with nonlocal boundary conditions. A new type of non-local boundary conditions has been identified, which has not been previously investigated. The boundary conditions of this type are represented by the contour integral over the boundary of the region from an unknown potential. In the general case, the obtained problem does not have a unique solution. The theorem of existence and uniqueness of the solution for the boundary value problem for the Laplace equation with nonlocal boundary conditions is proved. However, the requirement that the potential on the wire surface is constant allows us to prove the existence and uniqueness of the solution for considered problem. In order to illustrate the application of the developed approach we have solved numerically the problem for the sector-shaped cable with three cores. The values of potential and capacitive coefficients obtained by calculation are given. The error of the values of the diagonal elements of the matrices of potential and capacitive coefficients is estimated as less than 0.1%.

The purpose of this paper is to estimate the possibility of technical use of the 110 kV voltage lines (OPL) for the interconnection of the power systems of the Republic of Moldova and Romania, taking into account in the unified power system regime, which includes the power system of the CIS countries, of Moldova, Romania, Ukraine and other countries in the region. In the calculation scheme of the permanent synchronous regime of the integrated system, the interconnection zone of the Moldovan and Romanian systems was highlighted for the lines of 110 kV: Stanca-Costeşti, Ţuţora (Fai) - Ungheni and Hushi-Cioara. Transformer phase difference angle adjustment devices have been introduced in the 110 kV OPL to provide the bidirectional power shift regime. In the existing topology of electricity networks, power flows at the power system interface are directed from the Republic of Moldova to Romania. Changing the direction of the power flows is possible through the 110 kV OPL A when equipped with phase shift devices. The results of the calculations of the permanent regime have demonstrated the possibility of achieving the reciprocal power exchange regime between the interconnected power systems by adjusting the phase difference angle. It was shown the possibility of stable operation when using 110 kV overhead power lines as interconnection lines of the Moldovan and Romanian power systems. The issue of interconnection through the 110 kV lines is complex and requires an individual approach to how to achieve it.

Compact controllable high-voltage power lines (HVPLs) are a new generation of alternating current power transmission lines, representing the newest achievements in the field of power transmission and control means, new technical solutions for the design, insulation, connection layouts and control systems. The main distinctive features of the compact controllable HVPLs are: extremely reduced phase-to-phase distances adopted relative to the minimal required insulation distances (dielectric strength of the phase-to-phase gaps) at a maximum operating voltage and also under lightning and commutation overvoltage; new phase configurations, where tower’s grounded parts (poles, cross-arms, suspension hubs) placed outside of the interphase space; insulating elements (insulating spacers or screeds) between closely adjacent HVPL phases installation if required, fixing the selected distance between phases and dampening conductor’s vibration or galloping under severe weather conditions, which ensures high mechanical stability and reliability of the adjacent phases in spans; angular phase shifts establishment between the voltage vectors applied to the compact controllable HVPL adjacent phases; implementation of high-speed phase control devices and adjustable compensation devices (FACTS type). Compared to the conventional high-voltage power lines, compact controllable ones with FACTS devices ensure the following: 1.2-1.6 times increase in throughput; reduction of total costs per transmission capacity unit by 20 – 30%; 1.5-2 times alienated land reduction in case of equal power transmission; reduction of electric field intensity in the HVPL external space, and, hence, mitigation in the environmental effect; ability to control power flows and their directions; and total energy losses reduction in the power system.

Innovations in the nuclear industry are inextricably linked to economic evaluations of new engineering solutions. To improve the economic literacy of students of engineering areas of training at NRNU MEPhI, an innovative course on the economics of digital design and engineering in the nuclear industry has been implemented since 2016. The structure of the interdisciplinary course is modular, which makes it possible to involve in the teaching activity specialists who are most competent in the respective areas of training. To increase the involvement of students, a software and hardware complex has been developed, which provides through the wi-fi classroom system a permanent online contact of the teacher with students. During the lectures, students respond in real time through their gadgets (smartphones, laptops, tablets, etc.) to 5 questions on the materials of each specific lecture, and during the workshops - solve about a dozen problems in the explanations of the teacher also through gadgets. This at the end of each lesson allows the teacher on his laptop not only to have a list of responses of each student to the second, but also to adjust the subsequent sessions to the understanding of certain aspects of the course. The work of students in the network allowed even as a creative task to develop a technological package «Nuclear technology-2035», showing a promising vision of the development of the domestic nuclear industry. In 2016-2020, more than 1400 students of various engineering specialties were trained. Statistical processing of the results of the control of the educational process allows us to make preliminary conclusions about the abilities (giftedness) of students to certain activities described, including in the course materials. Software and hardware complex can be used for other educational programs, which, depending on the subject area of study allows you to form a kind of «digital portrait» of each student Инновации в атомной отрасли неразрывно связаны с экономическими оценками новых инженерных решений. Для повышения экономической грамотности студентов инженерных направлений подготовки в НИЯУ МИФИ разработан и около пяти лет успешно реализуется инновационный междисциплинарный курс «Экономика цифрового проектирования и конструирования в атомной отрасли». Модульная структура курса позволяет привлекать специалистов, наиболее компетентных в соответствующих направлениях подготовки. Для повышения вовлеченности студентов создан программно-технический комплекс, обеспечивающий постоянный интернет-контакт преподавателя со студентами. Студенты в режиме реального времени с помощью своих гаджетов (смартфонов, планшетов и пр.) дают ответы на вопросы в ходе лекций, решают задачи в ходе практикумов. В конце занятия преподаватель имеет ведомость ответов каждого студента с точностью до секунды и может корректировать последующие занятия с учетом понимания тех или иных аспектов курса. Работа студентов в сети позволила даже в качестве творческого задания разработать технологический пакет «Ядерные технологии-2035», показывающий перспективное видение студентами развития отечественной атомной промышленности. В 2016-2020 гг. обучение прошли более 1400 студентов различных инженерных специальностей. Обработка результатов контроля учебного процесса позволяет делать предварительные выводы о способностях (одаренности) студентов к определенным видам деятельности, описанным, в том числе, в материалах курса. Программно-технический комплекс может быть использован и для других образовательных программ, что в зависимости от предметной области обучения позволяет формировать своеобразный «цифровой портрет» каждого студента ИННОВАЦИИ, Выпуск 4 (258) 2021, Pages 59-66

The aim of the work is to develop technical measures to improve the quality of the power transmission process through electrical link, which contains a frequency converter based on a PST (phase-shifting transformer) with circular rotation of the output voltage phase in relation to the input, made according to the triangle scheme and controlled by means of power electronics. To achieve this goal, the use of longitudinal inductive elements (chokes) has been proposed as one of the measures that significantly improves the controlled mode parameters in the process of frequency conversion. The problem has been solved by performing computational experiments on simulation models of electrical links, combining two power systems with a frequency of 60 and 50 Hz, respectively. The structure of electrical links at various stages of the study has included several circuit variants of a frequency converter (single-channel circuit, dual-channel with reversing control winding sections, dual-channel circuit without reversing control winding sections) and has developed by authors earlier. In the process of research, the value of inductance of chokes has been changed, as well as their place of connection. The controlled transmission's characteristics have been analyzed as well. The novelty of the work lies in the use of longitudinally included inductive elements as a possible solution to the problem of improving the quality of power transmission when combining power systems with different operating frequencies using static frequency converters. The optimal values of the parameters of inductive elements, comprised between 0.03-0.035Hn for all circuit versions of the converter, have been identified.

For the purpose of calculation and studying of steady-state asymmetrical modes of operation of three-windings, three-leg power transformer with an arbitrary winding connection scheme the mathematical model is proposed. This model makes it possible to take into account electromagnetic coupling between the windings, located on different legs. Windings connection scheme in developed model can be arbitrary, including some more complex schemes such as “double zigzag”, “polygon”, “triangle with extended sides”, etc. As the initial data for the model elaboration it is used usual datasheet for power transformers, including nominal values of power and voltages of the windings, short circuit voltages of the winding pairs, power losses in no-load and short circuit modes, no-load current, as well as additional similar data on transformer zero sequence parameters, provided additionally by manufacturer. Use of zero-sequence data allows reflecting one of the most important features of a three-leg transformer, in comparison with three-phase group of single-phase transformers due to electromagnetic coupling between windings, located on different legs. This leads to some peculiarities of its asymmetric modes. Calculations and analysis of the usual steady-state asymmetric modes, including short circuits and phase breaks were carried out on the base of power transformer with windings connection scheme Yn/yn/d-11. The conditions were found out when the magnetic flux tends to exit the magnetic circuit, which can lead to additional losses and local overheating. For considered modes, vector diagrams of currents and voltages of the windings, as well as relative values of magnetic fluxes in the legs are constructed.

Factors affecting the production of electricity by photovoltaic (PV) power plants are studied. It is worth noting that reducing the shade and orientation to the sun are effective solutions for an increase in the production of electricity by these PV plants. A brief overview of the features of stationary installations and installations in the tracking of the sun is presented. The purpose of the paper is to justify, develop, and describe a generalized approach to analyzing the operation and methods of tracking the sun by the platforms with photovoltaic modules so as to increase the specific energy density obtained from a given surface of the photovoltaic installation. A concept is formulated and the generalized mathematical model is developed for different photovoltaic plants with fixed and mobile platforms, taking into account the shading effect of photovoltaic modules mounted on different platforms. Based on the decomposition concept, the optimization problem is solved on the criterion of the maximum value of the electric energy and the occupation of the smallest area of the site for a PV plants. A software for calculating the electricity produced by PV plants with stationary and mobile platforms was elaborated according to their location on the land meant for a certain PV plants. Specific electricity production kWh / (m2*day) indices were determined for different PV plants, taking into account the shading factor. It was found that the PV plants equipped with three-coordinate orientation systems can produce the largest amount of energy, in addition, providing higher energy performance indices compared to those of other types of PV plants.