Electricity

About the New Russian Federation Standard on Turbogenerators

2025-04-13T11:15:56+00:00

The article presents the results of the activities conducted by the Federal Agency for Technical Regulation and Metrology (Rosstandart)’s Technical Committee TC 333 "Rotating electrical machines" on the development and enactment of the standard for turbogenerators GOST R 70940-2023. The problems of harmonizing Russian and interstate standards with international ones are described. The connection of the new standard with the regulatory documents in force in the territory of the Russian Federation is demonstrated. A comparative analysis of the substantive part of GOST IEC 60034-3 previously used in the territory of the Russian Federation and the newly introduced standard is performed, which eliminates existing deficiencies, inconsistencies and typos, and takes into account the requirements for power equipment used in the Unified Energy System of the Russian Federation. The activities conducted by the Technical Committee TC 333 and its interaction with related committees are described. The new standard – GOST R 70940-2023 has been developed by specialists of Peter the Great St. Petersburg Polytechnic University with active initiative participation of specialists of JSC Power Machines, PJSC Forward Energo, JSC Sevkavelektroremont, JSC Rosseti STC, RPA Elsib PJSC, JSC Institute Gidroproekt, OJSC AAEM, OJSC ETC UralEnergoEngineering, National Research University Moscow Power Engineering Institute with assistance by TC 016, TC 322, and support by FSBI Russian Standardization Institute.

Development of a Fuzzy Controller for Damping Oscillations of a Flexible Suspended Load in the Electromechanical Systems of Crane Mechanisms

2025-04-13T11:31:15+00:00

The article addresses studies aimed at damping the vibrations that occur in the crane travel mechanisms when moving a load on a flexible suspension. An algorithm has been developed for developing a universal control unit based on fuzzy logic that adjusts the electric drive speed setting signal. A step-by-step development of a universal fuzzy controller in the MATLAB Simulink environment is presented, the use of which will reduce the load on processor hardware resources. The results of studing the use of the proposed universal fuzzy controller as a unit for damping vibration of a flexibly suspended load are presented. The use of the controller made it possible to reduce the amplitude of load fluctuations during transients and reduce it to zero in steady state by introducing a corrective addition to the signal coming from the intensity setpoint adjuster. An increase in the deviation of the load entails an increase in the correction signal output from the fuzzy controller, causing the movement mechanism to slow down, thereby resulting in a smaller angle by which the load deviates from the vertical position.

Persistent Current Switches for Control of the 1.5 T MRI Magnetic System

2025-04-17T09:02:17+00:00

The currently achieved level of technology development around the world makes it possible to construct superconducting (SC) magnetic systems with a helium-free cooling system that does not require replenishing it with liquid helium throughout the entire service life. A magnetic resonance imaging (MRI) with a 1.5 T magnetic system that operates in vacuum under helium-free cooling conditions is being developed in Russia. The article presents the design of a superconducting switch, commonly known as a persistent current switch (PCS), for controlling the MRI magnetic system during current input/output. The PCS operates, like the entire magnetic system, under helium-free cooling conditions. To optimize the PCS design and study its unsteady operating modes, a numerical model based on the finite element method has been developed, which solves the unsteady heat conduction equation. Two PCS operating modes are considered: standard current input or output and fast current output. The PCS winding temperature variations during its operation is presented. The mechanical stresses arising in the cooled PCS predicted by the finite element method are presented. The PCS experimental samples that meet the technical requirements for the 1.5 T MRI magnetic system are presented.

The Influence of Temperature on the High-Voltage Equipment Insulation System Dielectric Response

2025-04-17T09:22:44+00:00

Modern approaches to assessing the condition of high-voltage equipment are based on the measurement of insulation system parameters. In world practice, methods based on the measurement of polarization and depolarization currents in dielectrics are increasingly used to assess the dielectric insulation quality. In doing so, it is assumed that polarization processes are determined by the state of the dielectric, while the influence of external factors on the measurement results is as a rule not taken into account. The article addresses the study of the influence of external operational factors (the temperature and applied test voltage) on the polarization and depolarization currents, and the system dielectric response. As a result of the experiment, the dependences of polarization and depolarization currents on the temperature and applied test voltage were established. It has been found that the dielectric response function does not depend on the test voltage only at temperatures below 60 °C. This points to the need to adjust the methods of interpreting the high-voltage equipment diagnostic results obtained at higher temperature levels. A theoretical substantiation of the established dependences is given based on the physical processes occurring in the dielectric. The results obtained can be used to assess the condition and interpret the results obtained from diagnosing the insulation system of high-voltage electrical equipment (power transformers, electric motors, cables, etc.).

Determination of Transistor Losses in a Resonant Voltage Inverter

2025-04-17T09:55:59+00:00

The article addresses experimental studies of losses in a resonant inverter during its operation with different detuning degrees. The study is prompted by the increasingly growing need to achieve more efficient operation of powerful energy converters and improve the characteristics of power electronics products in terms of increasing conversion operating frequencies, reducing power losses in power components, and reducing dynamic overloads. Resonant voltage inverters are one of the most energy-efficient types of converters. In many cases however, numerical simulation does not demonstrate a radical difference in energy efficiency when the converter operates with different degrees of its detuning, which can cause the converter failure. The results of experimental studies are compared with the relevant data predicted using standard transistor models. A test laboratory bench has been assembled to determine the dependence of power loss in the resonant inverter transistors on frequency. A computer Spice model of a resonant inverter has been developed to explain the differences in losses depending on the detuning degree. The simulation results demonstrate that the dependence of transistor cell power loss on the frequency is not very strong with deviation from the resonance frequency, and do not show that it has such a significant effect. The conducted study makes it possible to see a somewhat approximate distribution of losses depending on the detuning type and draw a conclusion that the models of semiconductor shall undergo verification.

Reduction of Fire Hazard in Individual Residential Buildings under the Conditions of Unbalanced and Nonlinear Loads

2025-04-17T10:05:01+00:00

The article considers the possibilities of using methods and technical means to reduce the risk of fire-hazardous situations to occur in individual residential buildings (IRB) as a consequence of unbalanced operation modes caused by unbalanced and nonlinear loads. The maximum allowable current values through the neutral conductor of the IRB internal electrical network and in a 0.4 kV four-wire network under various temperature conditions have been determined. Based on the actual measurements of electrical energy parameters in the IRB internal electrical network, the connection of the newly developed balancing device to the IRB input distribution board was simulated. The effectiveness of using the balancing device was analyzed from the viewpoint of reducing the risk of fire to break out. It has been established that the use of a balancing device reduces heat losses, which can cause a fire hazard in the electrical network under study, by more than 60 %. The results obtained may be of interest to companies involved in the design and construction of IRBs, as well as to scientists who investigate unbalanced operating modes of low-voltage electric networks.

Investigation of a Radiation-Resistant Induction Motor with Ring Stator Windings (By way of discussion)

2025-04-17T10:30:51+00:00

The article addresses the development of a special-purpose motor designed to operate under the conditions of elevated temperature and radiation. The design of a multiphase induction motor armature having ring windings with ceramic insulation is considered. It is proposed to use the armature a new type for electric machines with a capacity of up to 20 kW. Unlike machines of the conventional design, the rotating magnetic field in the machine of a new type is produced using a specially arranged magnetic system. The presented armature design makes it possible to place the stator coils in assembling the magnetic system without damaging or deforming them, and the use of ceramic insulation will help increase the motor service life. The problem of how to produce a rotating magnetic field and distribute it in a magnetic system is considered. A prototype induction motor with ring windings has been designed and manufactured on the basis of a serially produced motor for general industrial use. At the first stage of the research, a digital experiment was conducted, the results of which were verified at the second stage using the prototype field tests.

Results of the General Meeting of the Electrotechnical Sciences Academy of the RF

2025-04-17T10:35:22+00:00

Vladimir Yakovlevich Frolov (to the 75th Anniversary of the Birth)

2025-04-17T10:37:29+00:00