Aleksey Bukreev

RELEVANCE of this study stems from the methodological gap between the agrotechnical requirements for self-propelled modular platforms (drawbar pull, operating speed, mass) and the parameters necessary for designing traction electric motors using the finite element method (external speed characteristic (ESC), CPSR). Existing methods do not account for the specifics of individual electric drives and the modern possibilities of mass variation. THE PURPOS E. To develop an algorithmic traction calculation methodology that transforms the initial agrotechnical parameters into a well-founded external speed characteristic of a traction electric motor for hybrid agricultural modular platforms with series transmission. METHODS. The methodology is based on traction balance equations, classical tractor theory, and analysis of empirical dependencies. A key feature is the introduction and systematic consideration of the operational mass range coefficient and the overload capability coefficient, enabling a transition from discrete mass settings to a continuous range. The calculation includes determining the required power, efficiency (taking into account energy efficiency classes), reduction gear ratios, and constructing the desired external speed characteristic. RESULTS . A family of external speed characteristics of traction electric motors was obtained, demonstrating the influence of varying parameters on the required Constant Power Speed Ratio (CPSR). It was found that increasing the design operating speed from 4 to 8 km/h with a fixed operational mass range coefficient of 1.66 reduces the required CPSR from 11.1 to 5.5. Based on the traction balance equations, a dimensionless complex for CPSR was derived, generalizing the influence of the speed factor, adhesion factor, ballasting factor, and overload factor. A strategy for unifying traction motors within a model series is substantiated: a single motor size covers the requirements of the entire series by software shifting of the base point on the ESC without recalculating the electromagnetic system. CONCLUSIONS. The developed methodology bridges the methodological gap between mechanical and electromagnetic modeling, acting as a crucial link in a closed-loop digital design cycle. It enables the formulation of accurate technical specifications for designing electric machines, optimizes the traction motor design for real operating conditions with variable mass and dynamic loads, and significantly reduces iteration time between interrelated engineering disciplines.

The reliability of power supply determines the operation of power networks. The literature reviews have revealed that insufficient attention is paid to the research of specific reliability indices necessary for planning and evaluation of energy saving efficiency. Therefore, the purpose of the work is to study the specific reliability indicators of 0.4 kV power networks. Among the analyzed indicators, we consider the flow of failures, the flow of intentional outages, specific values of disconnected power and undersupply of electricity, and others. The authors have analyzed statistical data on emergency and planned outages of 0.4 kV power networks in the Orel region over the period 2018–2023. In total, 12 787 overhead power lines with a total length of more than 10 thousand kilometers have been examined. Based on the analysis, the authors identify the values of specific reliability indicators and trends in their changes over 6 years and analyze probable reasons for these changes. It has been revealed that the values of the failure flow parameters do not exceed the reference values until 2022 inclusive, and in 2023, they exceed the reference values by 1.2 times. In 2022–2023, there was a significant increase in the number of both emergency and intentional (planned) outages; the flow of failures per 100 km of 0.4 kV lines in 2023 was 29 per year, and intentional outages constituted 71 per year. The values of specific disconnected power per outage decreased by 17.5 times in 2023 as compared to 2018, the average value per outage was 0.0009 MW. The specific value of undersupply of electricity per consumer per year is in the range between 1 and 5.7 MWh/consumer for emergency shutdowns, and 3 to 8.1 MW h/consumption, according to the new plan. Specific reliability indices allow assessing the efficiency of 0.4 kV distribution networks in a particular region and can be used in assessing the effect of implementing measures to improve the reliability of power supply.

The article deals with seasonal redundancy of power supply to rural consumers, proposes technical means for seasonal redundancy systems that allow redundancy of three groups of consumers (or electrical receivers) that have a seasonal nature of work and one all-season group.

The article discusses the improvement of the efficiency of technical means of inspection of electrical networks of agricultural facilities, which make it possible to study the modes of operation of the electric network, electrical equipment and electrical receivers, to assess the consumption of electricity by rural consumers, the use of which is justified by a complex criterion of efficiency. Single (partial) indicators of the effectiveness of technical means of inspection of electrical networks of agricultural facilities were selected: battery operating time, the number of measured parameters, the number of measurement points, measurement error, the frequency of data acquisition, labor costs, installation and adjustment of electrical network inspection tools and the cost of equipment. The actual and required (desired) values of particular indicators of the efficiency of technical means of inspection of electrical networks of agricultural facilities have been determined, the values of their importance coefficients have been calculated.

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.

The article presents data on the values of working currents and short-circuit currents in rural electric networks of 10 kV on the example of lines in the Oryol region, Russia. The results of processing statistical data on the values of these currents are given. Conclusions are made about the area of coincidence of the values of working currents and short-circuit currents.

The article presents the developed method for assessing electricity losses in power transformers in the process of their operation. The method allows you to make an assessment without disconnecting the load of the transformer and makes it possible to rank losses for short circuit losses, load losses and idle losses. This makes it possible in the future to minimize the labor costs associated with conducting surveys of power transformers.