Modular designs for the underwater portions of an above-water and a deep-sea unmanned vehicle power-supply system are proposed. This system is based on transistor dc/dc converters with series half-bridge resonant inverters. The features of the underwater portion, which contains several modules connected in series across their input circuits, are identified. A control option for the modules of the underwater portion is proposed and validated, ensuring stable and reliable operation of the power-supply system across a wide range of loads. Simulation results for processes in the power-supply system’s underwater portion under steady-state and transient conditions are presented.

In 6- to 10-kV distribution networks operating with an isolated neutral, current protection based on monitoring the fundamental frequency component of the zero-sequence current is mainly used for protection against single-phase ground faults. The selectivity and stability of such protection are significantly affected by intense transient processes during intermittent arcing single-phase ground faults. One promising area for improving current protection against single-phase ground faults is to increase the selectivity and stability of their operation based on recognizing the types of ground faults using a multiparameter approach to implementing relay protection. To develop and study the methods and algorithms for recognizing the types of ground faults in 6- to 10-kV networks with an isolated neutral and to assess the effectiveness of their application in order to increase the selectivity and stability of current protection against single-phase ground faults, simulation modeling in MATLAB, SimPowerSystems, and Simulink was used. The configuration and parameters of the simulation models were selected taking into account the main features of 6- to 10-kV distribution cable and overhead networks of industrial, urban, and agricultural power-supply systems, determining the characteristics of steady-state and transient modes during single-phase ground faults. The principles of implementation and a diagram of multiparameter current protection against single-phase ground faults for 6- to 10-kV networks with an isolated neutral were developed, ensuring the recognition of all considered types of ground faults (stable, intermittent arc, and nonhazardous arc intermittent for the network) and the ability to automatically select on this basis the most effective method of its action (signal or shutdown). The results of functional tests on simulation models confirmed the efficiency of the developed algorithms for the operation of multiparameter current protection for all considered types of single-phase ground faults in 6- to 10-kV networks with an isolated neutral. The developed technical solution implements multiparameter current protection against single-phase earth faults, providing increased selectivity and stability of operation for all types of earth faults compared to traditional designs of current protection against this type of damage, continuity of operation not only for stable, but also for the most dangerous arc intermittent earth faults, as well as the ability to select the method of operation of protection for these types of earth faults.

Linear generators, used, among other things, as autonomous power sources and electromechanical shock absorbers, convert the energy of oscillations into electrical energy with a linear reciprocating motion of the inductor. The EMF of the generator has a nonsinusoidal shape due to higher spatial and temporal harmonics. The change in the speed of the inductor is determined by the nature of the acting forces, but in the analysis it is usually assumed to be harmonic with a sinusoidal distribution of magnetic induction. Reduction of EMF harmonics is possible in an electrical system containing a linear generator and a magnetic-fluid damper, due to the improvement of designs based on a refined analysis. Reduction of spatial harmonics of EMF is carried out by improving the tooth zone and the armature winding, using magnetic fluid, and reducing temporal harmonics due to the provision of the electrical system of the necessary change in the linear speed of the inductor. The analysis was performed in the ANSYS Electronics Desktop, ANSYS MAXWELL, and Elcut packages. An electrical engineering system for converting oscillation energy based on a linear generator and a magnetic-fluid damper was developed, its functions, features, and operating modes were described. Combined device designs, a three-phase combined winding with an EMF increased by 2% and a sinusoidal distortion coefficient reduced by 20% were developed. Mathematical analytical and numerical methods for calculating characteristics based on finite-element modeling were proposed. The developed electrical-engineering system allows for efficient redistribution of oscillation energy between a linear generator and a magnetic-fluid damper, and ensures a reduction in higher harmonics in the EMF. The use of magnetic fluid controlled by a magnetic field allows regulating the resistance force to the inductor movement, carrying out controlled viscous energy dissipation in the layers of the fluid, dampening oscillations, increasing the magnetic conductivity of the gap, to increase the magnetic flux, reducing the pulsations of the tooth harmonics of magnetic induction, increasing heat removal from magnets and windings, and providing effective lubrication.

This article considers a method for adjusting, from oscillations and asynchronous running, the operating values of digital starting elements of distance and high-frequency protections running respond to increments in phasor currents. The influence of nonstationary transient modes of an electrical system on the behavior of algorithms for measuring increments by blocking starting elements at various types of power swings is shown. The results of a comparative study of the sensitivity of digital measuring elements on the basis of the discrete Fourier transform and nonrecursive filters are presented. These results can be used in designing and selecting operating values of relay-protection functions.

The methods of optimizing the technological properties of an electrically insulating heat-resistant varnish based on polymethyl phenyl siloxane resin and acrylic copolymers are considered. It has been found that a rise in the proportion of acrylic film-forming agents in polymethyl phenyl siloxane resin accelerates the drying of varnish compounds and makes them less dense and more viscous. The addition of methyl methacrylate and butyl methacrylate copolymers into polymethyl phenyl siloxane resin increases the average molecular weight of the varnish compounds, makes the coating less elastic, and decreases its strength and hardness. It is shown that coatings obtained using Degalan LP 65/12 and Dacryl SP 652 as film-forming copolymers exhibit the lowest brittleness. As a result, the physical modification of polymethyl phenyl siloxane resin with high-molecular acrylic copolymers improves the physical and mechanical, and strain-and-strength properties of this resin.

In electric vehicles used at unstable loads and frequent braking and acceleration, the optimization of the traction drive is crucial for improving the overall energy efficiency of electric vehicles and increasing the drive range. Modern components and advanced technologies, such as new materials and intelligent control systems, play an important role in achieving these goals. The article discusses the development of an efficient electric vehicle power plant based on the driving cycle. The WLTC (Worldwide Harmonized Light Vehicles Test Cycle) global driving cycle is used as a reference for determining loads and operating conditions. The battery-pack load was calculated. The calculations were used to compare and select the most efficient storage device for running an electric vehicle based on the WLTC cycle.

The d-axis inductance (Ld) of the negative-salient permanent magnet synchronous motor (NSPMSM) is larger than the q-axis inductance (Lq). Compared with the traditional positive-salient permanent magnet synchronous motor (PSPMSM), the NSPMSM has the characteristics of wide constant-power speed range, strong overload capacity and the permanent magnet is not easy to demagnetize. In this paper, a new type of NSPMSM is proposed by using magnetic bridge to increase the Ld and W-type permanent magnet to decrease the Lq. Firstly, according to the working principle of the NSPMSM, a new motor structure is proposed, and the equivalent magnetic circuit of the new motor is established. Secondly, the combination of single objective optimization and multi-objective optimization is proposed. The influence of design variables on the optimization objective is measured by sensitivity index, and then the optimal model of motor is obtained by response surface method. Finally, finite element analysis is used to compare the performance of the new motor and the traditional motor. The NSPMSM constant-power speed reaches three times of rated speed. The theoretical analysis results are consistent with the simulation results, and the effectiveness and feasibility of the new type of motor are verified.

An assessment of power-transformer overload in the power system of the Altai Republic and the Sayano-Shushenskaya HPS resulting from geomagnetically induced currents (GICs) has been performed. A unit for measuring GICs in the Altai Republic’s energy system and the GIC measurement results in the spring and summer of 2024 are presented. A physicomathematical model has been developed that makes it possible to calculate GICs based on data obtained from the Baigazan magnetic station. The results of direct measurements are qualitatively consistent with the results obtained in the course of simulation. By using the model, a theoretical assessment of the GICs at the substations of the 500-kV power-transmission line between the Sayano-Shushenskaya HPS and the Novokuznetsk HVS has been performed. For the case of the strongest magnetic storm in 20 years on May 10–11, 2024, the calculated values of the GIC amounted to about 100 and 50 A. Based on literature data and the measurements performed with the use of a testing bench, estimates have been made for the increase in the open-circuit current of power transformers owing to GICs at the Ininskaya high-voltage substation (HVS) in the Altai Republic power system (7%), Novokuznetsk HVS (14 A, 1500%), and Sayano-Shushenskaya HPS (20 A, 1000%) are given. It is concluded that these power systems are resistant with respect to such impacts.

Based on an analysis of the parameters of the traction power-supply system of a real intersubstation zone, an algorithm for calculating the traction network resistance was constructed. To determine the reserved values of voltages and currents of the traction network, a scheme for installing devices for collecting data at traction substations was proposed; based on these data, a change in measured values depending on instantaneous schemes was obtained. Based on the available real data, a traction-network section was simulated, on the basis of which the traction network resistances was calculated. To determine the voltage drop and complex resistance of the traction-network section, calculations of the traction power-supply-system modes were carried out in a simulation model. High convergence of voltage losses in the traction network and the calculation results in the software package was shown.

The justification of a system for diagnosing the technical condition of power semiconductor devices, based on the principles of nondestructive testing has been reviewed. An assessment of the current state of protection means for semiconductor products is given. The theoretical foundations forming the basis for the development of such systems are presented, along with the results of experimental studies on a prototype device.