Electrical Units and the I.E.C.

Finite-time event-triggered consensus control for high-speed train with gradient resistance

DURING last year the use of electricity for the melting and heat treatment of iron and steel in Great Britain considerably increased. There has been a revival in the demand for arc furnaces, a number of which, varying in capacity from 500 to 6,000 kilowatts, are being installed. In the Electrical Review of April, Mr. D. Campbell states that the furnaces ordered from a single manufacturing company during last year would consume about a 100 million electric units a year. The cost of the annual power bill for these furnaces alone would be about £200,000. A furnace of 6,000 kilowatt capacity, probably the largest electric melting unit in Europe, has just begun operation in Sheffield. Within its small area of furnace hearth (13 ft. diameter), as much energy is consumed per day as the aggregate loads of Cambridge, Salisbury and Tonbridge. Unfortunately, the requirements of larger and interconnected power stations make it essential to install higher rupturing capacity switch-gear, and this constitutes a heavy charge on small firms which may want to use electric furnaces. Seeing that the cost of the energy consumed by the furnace during its average life (ten years) is about thirty times the original cost of the complete installation, the companies should offer attractive conditions to steel manufacturers. The extreme purity of arc furnace steel owing to the absence of slag inclusions is now generally recognized, and for many types of forging this steel is specified. The choice between high-frequency furnaces and are furnaces is difficult to make. Although the capital expenditure for high-frequency furnaces is much higher, yet when melting operations only are required they are cheaper to work.

SEVERAL of the many interesting papers presented to Section 2 of the International Congress of Electricity held in Paris last summer dealt with electrical units. Thirty years ago the general opinion prevailed that the realisation of the ‘international’ electrical units was much easier than that of the so-called ‘absolute’ units based on the c.g.s, system, but experience acquired in the last twenty years has considerably modified this view. H. L. Curtis, in Paper No. 4, discusses the various methods in use for the measurement of current in ‘absolute’ c.g.s. units, and urges the furtherance of investigations. The determination of the ampere in the c.g.s. system of units can at present be carried out with an accuracy probably higher than that attainable in the determination of the ‘international’ ampere by the deposition of silver.

Introduction. Fires of voltage-carrying electrical units are most dangerous and difficult to put out. Personnel of fire emergency response units are at high risk of electric shock when extinguishing such fires. Electrical units have recently obtained a new are of application, that is, electric cars. Electric car design entails the use of high-capacity batteries and high voltage electrical equipment, which pose a higher fire hazard. The objective of this article is to analyze potential assets to be protected and assess existing electrical fire extinguishing methods to substantiate principal areas of research into design of safe fire extinguishing systems designated for electrical units installed on motor vehicles.Main (Analytical) part. The fire extinguishing of the items, that have electrical units to be extinguished without any electricity outage, must be performed by the fire departments that have appropriately trained and equipped personnel. However, in the event of an electric car fire, it is impossible to forecast which fire department will be nearby and how well it will be equipped. The design features of electric vehicles show that potential sources of the fire hazard include lithium batteries and electrical circuit elements. These factors explain the need to consider the problem of extinguishing self-contained electrical fires inside motor vehicles from the standpoint of electrical safety. It is suggested to identify the fire extinguishing method in furtherance of the analysis of a set of principal fire extinguishing methods with regard for the design of efficient firefighting appliances that ensure safe extinguishing of electric car fires.Conclusions. It is expedient to use the pulse application of a fire-extinguishing agent that prevents current leakage while extinguishing various types of electrical appliances, including those installed on motor vehicles. The effects of exothermic reactions, involving lithium-containing elements, were not analyzed when solving this problem. This research will serve as the basis for conceptual technological solutions designated for fire emergency response units responsible for extinguishing electric car fires.

The work is devoted to the protection of a spacecraft from the influence of unacceptable internal vibration sources. The urgency of reducing the vibration activity on board the spacecraft to improve the accuracy of the target equipment is indicated. A particular problem of vibration protection of the spacecraft platform from a vibration source – an electric pump unit of a liquid thermal control system – is being solved. The basic requirements for electric pump unit vibration protection have been determined. Possible ways to reduce the level of vibration excited by the electric pump unit on the surface of the spacecraft fixation are considered. Particular attention is paid to such vibration protection methods as damping and vibration isolation, implemented by installing special vibration protection devices between the source (electric pump unit) and the object (spacecraft) – vibration isolators and vibration dampers. The principles of operation of vibration dampers and vibration isolators, the most common materials for vibration dampers are described. Examples of constructive solutions for linear single-axial vibration isolators are considered, recommendations for the use of promising products are developed. Particularemphasis is placed on the use of metal rubber as a material for vibration isolators. With regard to a specific design of electric pump unit, a diagram of the spatial structure of vibration isolation is proposed. Formulas for calculation are given in detail, a mathematical model of the vibration isolation system is developed. The procedure for calculating the parameters of the system has been formed. Based on the model, the maximum possible level of vibration suppression in the mid-frequency region was determined. Minimum required number of operable pixels was identified for monitoring the water surface with sufficient accuracy and reliability.

A small Janus molecular dimer, as external electric field (Fz) manipulated both a molecular clam switch and a novel electric information storage unit, is found by quantum chemical computations for the first time. The molecular clam switching is intriguing and reversible. A critical Fz value of 95 × 10−4 au causes a dramatically open change in conformation from Closed form to Open form. And a small reversed electric field of Fz = −10 × 10−4 au performs a close change from Open form to Closed form. In the switching process, owing to the existence of a great electric dipole moment (μ) contrast between 0 and 22.13 D, the molecular clam switch may serve as an electric information storage unit. Gratifyingly, the reading, writing, and erasing of binary information on the electric information storage unit are easy. And further calculations show that Janus graphene fragment dimer can also serve as a molecular clam switch. Thus, this work proposes a new molecular switch prototype in the invention of artificial molecular machines, and a novel electric information storage unit in the field of molecular electronics.

Multi-agent reinforcement learning with graph convolutional neural networks for optimal bidding strategies of generation units in electricity markets

In Ukraine, the number of farms, private land users and protected soil structures has increased significantly in recent years. To increase the efficiency of vegetable production, small-sized mobile units in the form of motoblocks with internal combustion engines of domestic and foreign production have been widely used. However, during the operation of mobile units with internal combustion engines in greenhouses and hotbeds, the noise level and air pollution increase, which negatively affect not only people but also plants. The disadvantages of motoblocks with internal combustion engines should also include a fairly high specific consumption of liquid fuel, which has a high cost, difficulties in starting and stopping the unit, as well as the relatively low reliability of the internal combustion engine. More promising for work in protected soil structures are mobile units with traction motors, called electric motors, as environmentally friendly units that do not have these shortcomings. The main technical characteristics of the experimental sample of a small-sized electrified soil-cultivating motoblock are given in the work. The structural scheme of the power energy channel of the electric motor unit is substantiated, which clearly demonstrates the processes of energy conversion in it. The equation of energy balance of the electric motor unit and the main energy ratios that determine the properties of the traction motor in the drive of the electric motor unit are obtained. The algorithm of optimal control of a direct current traction motor by the maximum efficiency for direct current motors of serial and mixed excitation is substantiated. The results of field tests of the prototype of the electric motor unit are presented. The analysis of the obtained results of experimental researches of the electrified tillage motor-drive driven by the direct current motor of sequential excitation testifies to the reduction of specific energy consumption for the main types of tillage by 12-15%.

Abstract: Educational Institutions are often under pressure for cost cutting. Electricity charges, especially in a residential institution, is one of the biggest drain on finances. In this case study, we would like to discuss the grid connected roof top solar project in Army Institute of Technology (AIT), Dighi, Pune. This 350 kW system has been installed without any cost to AIT, on Build-Operate-Transfer (BOT) model, for 25 years at the rate of Rs 6/- per electricity unit. The power generated by the system is approximately 1000 to 1200 electricity units per day as against a requirement of about 1800 to 2000 electricity units per day. Net Metering Policy implemented by Maharashtra Government enables AIT to send excess electricity generated during day time back to the grid. This excess power given to the grid is credited back during night time. A new Net Meter has been installed in AIT that provides daily status of the power import/export. This has resulted in Cost Savings of nearly Rs 1,50,000/- per month which comes close to Rs 18,00,000/- per annum. Keywords: AIT, Build-Operate-Transfer, cost cutting, grid, roof top, solar

An automatic design method for power systems, to control electrical loads provided by customers and to ensure the power supply for the loads, is described. This method features (I) an electrical equipment model including the possible connections among each electrical equipment, (II) knowledge association networks to reduce maintenance cost of knowledge-base and to improve efficiency to select/specify electrical equipment, (III) a planning algorithm to find electrical path to control the electrical loads and to ensure the power supply, and (IV) the reactive re-design to automate to edit the power systems. APEC3 (Advanced Plant Engineering Cycle tool version 3) is an automatic design tool for power systems that supports electrical engineering processes in developing single line diagrams, specification balance statements (design rationales) and item lists. When engineers modify equipment specifications, APEC3 invokes the redesign function which automatically changes the specifications of all relevant equipment. To evaluate the effectiveness of the method, APEC3 was used in designing practical power systems of steel plants. The results showed that APEC3 can reduce the design time to 1/8 as compared to the usual design time. Therefore, the engineers can find optimal specifications of the power systems by evaluating a number of possibilities.

The results of additional bilateral comparison of initial standards of the impulse electrical voltage unit were considered. As a result of comparison there were confirmed announced uncertainties and calibration and measurement capabilities of the participants of comparison. The comparison was carried out under guidance of COOMET (project 710/RU-a/16) оn the initiative of national metrology institutes (NMI): VNIIFTRI (Russia) and BelGIM (Republic of Belarus). The comparison involved national standards: the State primary standard unit of the impulse electrical voltage unit (GET 182-2010, VNIIFTRI) and the original standard of the impulse electrical voltage unit BelGIM. Step pulse generator TMG030010SN11-M1 was used as a traveling standard. The values of the impulse electrical voltage, reproduced by means of traveling standard, were measured by national standards.The purpose of comparison was to confirm confidence in the measurement results and calibration certificates, issued by the NMI in the field of impulse electrical voltage measurements. In the comparison VNIIFTRI acted as a pilot laboratory. Measurements of impulse electrical voltage by means of traveling standard were carried out in the following order: first – measurements of impulse electrical voltage on GET 182-2010, then – on the original standard of BelGIM and finally – again on GET 182-2010. Processing of the results of comparison according to χ2(i) criterion showed that χ2(i) criterion values (calculated on the basis of the measurement results) doesn’t exceed a critical value χ2, that is the objective confirmation of announced uncertainties, declared by the participants of comparison.

Link for citation: Totanov A.S., Molchanova V.A., Urazakov K.R. Study of the performance of the dynamic level stabilization system operation in the wellbore equipped with an electrical submersible pump unit. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 210-219. In Rus. The relevance of the study is related to the widespread use of electrical submersible pump units in the production of low-viscosity oils and water-gas-oil emulsions at this stage of development of mechanized production. However, the current production conditions associated with changing reservoir parameters bring to the fore a number of technical problems that need to be solved. One of these challenges is the phenomenon in which the dynamic level of the well decreases due to changes in reservoir parameters (reservoir pressure, productivity factor, etc.). Decrease of dynamic liquid level in the well leads to complications during operation of electrical submersible pump units. As a consequence, the increased cavitation in impellers is possible due to pressure reduction on the pump intake, and also full pump supply failure is not excluded at significant reduction of the dynamic level of the borehole fluid. In this relation, a technical solution, consisting in installation of bypass device (electrical valve) above the place of suspension of electrical submersible pump plant to maintain stable dynamic liquid level in the well and avoid complications during pump operation, was suggested. To confirm the feasibility of the dynamic level stabilization system, a mathematical model was developed to evaluate the effectiveness of complication prevention with the help of the proposed technical solution during the operation of the electric centrifugal pump unit. The main aim of the research is to develop a calculation method for studying the dynamics of the dynamic level stabilization system. Objects: an electrical submersible pump unit in conjunction with a system for stabilizing the dynamic level of the well. The influence of the diameter and length of the electrical valve on the efficiency of the dynamic level recovery was studied, taking into account hydraulic losses during the system operation. Methods. The research method is reduced to numerical solution of differential, linear and non-linear equations describing flow and pressure at electrical submersible pump unit outlet in steady-state mode, fluid flow through the electrical valve taking into account hydraulic resistances, flow of hydrodynamic processes in annular space during stabilization system operation, that is change of fluid level above the pump depending on borehole conditions and design parameters of electric valve. Results. Effect of parameters of the bypass valve – the diameter of flow section and length on dynamics of change of a liquid level above the pump, as well as the impact of liquid properties, namely its viscosity on intensity of restoration of a liquid level above the pump was studied. It was found that when the diameter of the electrical valve is increased, more intensive restoration of the liquid level above the pump is observed due to the reduction of hydraulic resistance in the valve cavity. Similarly, it was found that with increase of electrical valve length, as well as with increase of viscosity of liquid, coefficient of flow and intensity of liquid level recovery above the pump decreases respectively.

The magnetizing current inrush appears in electrical power units equipped with transformers in case of no-load energizing of the power transformers and in a number of other cases. This phenomenon could cause a false triggering of the current protection. To prevent incorrect actions of the current protection during the magnetizing current inrush a protection blocking is carrying out. The blocking principle operation is based on the fact that in a three-phase system in normal mode and in case of symmetrical short circuit the first harmonics contained in the phase currents of electrical installations form a direct sequence and the second ones – the negative sequences. In case of an asymmetric mode, including an asymmetric short circuit, the negative sequence appears, formed by the first harmonics that are part of the phase currents of the specified system. In magnetizing current inrush modes, second harmonics of significant magnitude are present in phase currents, which form the negative sequence. Based on the analysis of the information parameters of the specified sequences currents, identification of the magnetizing current inrush and short-circuit modes is performed with the implementation of the protection blocking if necessary. The study of the current protection blocking functioning was performed using computational experiment by analyzing the calculated changes of blocking parameter compared with the threshold setpoint. The specified researching is done by using the digital model that is implemented in the dynamic modeling environment MatLab-Simulink. As a result of the performed calculations, the principal operability of the proposed current protection blocking was confirmed that provides a fairly reliable identification of the magnetizing current inrush and short-circuits modes, regardless of the degree of saturation of current transformers. It was found that the proposed principle of the current protection blocking has a higher sensitivity in comparison with the classical one based on the estimation of the ratio of the second and first harmonics of the phase currents. In short-circuit modes in an electrical power units the proposed blocking causes a current protection operation delay that can be reduced by digital filters performance improvement.

The article presents research results and issues related to of magnetic component of electromagnetic field on the environment and electronic systems used in the electric traction unit. The electronic systems used and built into an electric power unit are operated in a wide variety of environmental conditions. Electrical and electronic systems with different purposes coexist on the vast railroad area, and an important operational problem, apart from environmental changes in which these technical objects are operated, is also the issue of external and internal electromagnetic compatibility. Depending on the extent of the railroad area, the intentional or unintentional emission of electromagnetic fields over a range of frequencies, the construction, technical configuration and method of ensuring electromagnetic compatibility for the electrical and electronic systems in use and electronic systems in use are different. It is necessary to skillfully and appropriately use all measures included in the electromagnetic compatibility pyramid to ensure the appropriate level of robustness, immunity and susceptibility of the above mentioned systems. Due to the impact and propagation of electromagnetic waves in the railroad environment, individual frequency bands of interfering signals should be considered separately for the whole spectrum of interfering signals. The article presents the results of research on the generated magnetic fields from the very low frequency (ELF) range by electric power units. Diagnosing the electromagnetic environment over the entire frequency range enables the realization and proper protection of the electrical and electronic systems used in an electric power train from the effects of unintended interference. Knowledge of the parameters of interfering signals - e.g. amplitude, frequency range, spectrum, etc. - will enable designers of electrical and electronic train systems systems to properly protect these facilities from adverse environmental conditions.

The design of an electric arc plasma unit with a cylindrical hollow working chamber and controlled electric arc producing low-temperature plasma, which can be used for surface treatment of metal products, is considered. The design of a regulated power supply of the electric arc part of the installation with a capacitor matching circuit and a pulse control unit of the electric arc current is proposed. The arc current continuity is ensured when regulating the power released in the electric arc. The amount of plasma produced is regulated by simultaneously changing the current in the arc and the flow of plasma-forming gas supplied to the arc burning area. The arc position is stabilized by creating an external electromagnetic field. An experimental electric arc plasma unit with a cylindrical working chamber and consumable graphite electrodes was created. The correlation between the power of the main elements of the unit is determined experimentally. The results of the study of processes occurring during electromagnetic arc drawing and plasma production are presented.