Individual Power Supply Research Articles

(Invited) The Design, Fabrication, and Operation of a MW-Scale Low-Temperature Electrolyzer System to Support Industry and the U.S. Dept. of Energy

Over the last 15 years the National Renewable Energy Laboratory (NREL) has supported industry and the U.S. Department of Energy by providing independent evaluation and performance validation of next generation electrolyzer stacks. Designated a U.S. Department of Energy user facility, the Energy Systems Integration Facility (ESIF) houses a comprehensive balance-of-plant infrastructure designed to support a wide range of drop-in electrolyzer stacks with capacities of up to 1 MW direct current (DC) electrical power. This NREL designed and fabricated infrastructure includes four individual power supplies (250V, 4000A Total), high-quality and high-flow deionized water (DIW) supply (up to 300 GPM), water polishing and particulate filters to achieve better than 10MΩ-cm resistive water, heat rejection via a plate heat exchanger and facility chilled water, gas/liquid phase separation of hydrogen and oxygen from water, and a hydrogen dryer bed to reduce water vapor content to less than 5 parts per million by volume to enable compression, storage and use in a wide variety of applications including light- and heavy-duty fueling, onsite fuel cell research and development (R&D), and biological and thermochemical processes requiring hydrogen. Safety, monitoring, data archiving, and control of the electrolyzer and balance of system are achieved using custom controls programmed specifically to achieve a safe and flexible architecture.Robust and redundant safety systems ensure safe and reliable long-duration, unattended operation of the electrolyzer with downstream compression equipment and systems consuming the product gas directly from the stack. Working with a small business, NREL is working to develop a low-cost individual cell voltage (iCVM) monitoring system capable of monitoring 100’s of cell voltages in the 2 – 3V range at a rate of 1 sample per second. The presentation will highlight critical safety considerations including reliable hydrogen-in-oxygen monitoring, lessons learned, and performance date taken over last 15 years of designing, building, and operating lab- and megawatt-scale low-temperature water electrolyzer systems.

ПРИМЕНЕНИЕ МЕТОДОВ ОБОСНОВАНИЯ МЕРОПРИЯТИЙ ПО ЭНЕРГОСБЕРЕЖЕНИЮ В СИСТЕМАХ ЭЛЕКТРОСНАБЖЕНИЯ ГОРНОДОБЫВАЮЩИХ ПРЕДПРИЯТИЙ

The paper uses the methods of mathematical modeling and instrumental control to justify the introduction of energy-saving measures and technical solutions in the power supply systems of mining enterprises. An assessment of the implementation of energy saving methods in electric drive and power supply systems at mining enterprises demon-strated the possibility of achieving a multiplier economic effect with the right approach to the implementation and subse-quent operation of energy-saving technologies. The energy saving potential was shown in the industry in ge¬neral, and in mining enterprises in particular. For example, in some areas of enterprises, such measures as reactive power compensa-tion, the introduction of automated electric drive systems, the development and pilot operation of power quality control systems with continuous recording of indicators were considered. The mathematical modeling method was implemented using the MatLab software package which has proven itself in engineering calculations around the world. Instrumental control and evaluation of power quality indicators were carried out in accordance with the requirements of GOST RF 32144–2013. As a result of the potential optimization of individual power supply systems, the estimated total economic ef-fect due to energy savings was obtained. The figure approached 28 million rubles per year, which is on average 20% of the cost of electricity consumption of the considered sites of mining enterprises.

ОЦЕНКА ВОЗДЕЙСТВУЮЩИХ ФАКТОРОВ И ПРОГНОЗИРОВАНИЕ ЭЛЕКТРОПОТРЕБЛЕНИЯ В РЕГИОНАЛЬНОЙ ЭНЕРГОСИСТЕМЕ С УЧЕТОМ РЕЖИМА ЕЕ ЭКСПЛУАТАЦИИ

The article is devoted to the research of the assessment of influencing factors and forecastingof power consumption in the regional power system, taking into account its operating modes.The analysis of existing methods of forecasting energy consumption is carried out. The choice of aforecasting method using an artificial neural network is justified. An algorithm for creating a neuralnetwork for short-term prediction of electrical load is considered. The relevance of the work isdue to the requirements of the current legislation for forecasting electricity consumption in orderto solve the problem of maintaining a balance of power between the generating side and the consumptionof electric energy. At the same time, one of the main tasks related to the generation ofelectric energy and its consumption is the task of maintaining a balance of capacities. On the onehand, with an increase in the planned load, interruptions in the supply of electricity may occur, onthe other hand, a decrease in electricity consumption will also lead to a decrease in the efficiencyof power plants, and ultimately to an increase in the cost of electricity both for the wholesale electricitymarket and for the end user. The developed neural network model reduces the task of shorttermforecasting of power consumption to the search for a matrix of free coefficients by trainingon available statistical data (active and re-active power, ambient temperature, date and index ofthe day). The received NS model of short-term forecasting of power consumption of a section ofthe district 10 kV electric grid takes into account the factors: – time, - meteorological conditions,– disconnections of individual power supply lines of cottages, – operating mode of electricity consumers.Predictive estimates of the power consumption of the power system have been obtainedbased on the data of the electricity consumed by the outdoor temperature, the type of day, etc. Themodel for predicting the magnitude of the consumed active and reactive power is quite workable,but at this stage still has a fairly high level of forecasting error. To improve the accuracy of forecasting,it is necessary to increase the database that makes up the training sample, because at themoment the available data cover a time period of only 3–4 months. The results of the analysisshowed that forecasting reactive power consumption causes the greatest difficulties.

Advanced power transformer with improved parameters for rural electrical networks

The problem of power quality supply is relevant for rural electrical networks, due to long distance and branching, as well as connection of a large number of single-phase and non-linear loads. Asymmetry of electrical loads causes voltage asymmetry, which adversely affects the operation of all elements of the electrical system, causing additional power losses, reducing the service life of electrical equipment and its economic performance, as well as reliability of operation of individual electrical equipment and power supply system as a whole. Reduction of voltage asymmetry can be ensured by rational construction of electrical network circuit and use of special correcting devices. The authors consider it reasonable to use relatively simple and reliable by design and inexpensive power transformers with a “star - double zigzag with a zero wire” (Y/2Zн) winding connection circuit with a neutral winding connection group. The paper deals with design and processes of converting electrical energy in a transformer. It has been proved that phase EMF of the secondary winding coincides in phase with the same EMF of the primary winding, i.e. the proposed circuit has a neutral windings’ connection group. Results of theoretical studies of transformer operation with an asymmetric and non-linear load are presented. Decrease in voltage asymmetry is due to the neutral sequence components compensation. Decrease of the higher harmonic voltage components level occurs due to the compensation of the higher harmonics multiplied three times. It is theoretically substantiated that transformer will not emit higher harmonic components of zero sequence voltages into the supply network. Experimental studies have confirmed the theoretical conclusions that a transformer with Y/2Zн winding connection circuit allows obtaining the highest level of voltage symmetry with an asymmetric load. In single-phase load mode, the values of voltage unbalance factor in reverse sequence do not exceed 1.7 %, in neutral sequence - 2.9 %. The transformer allows obtaining 1.2-1.5 times lower value of total harmonic components factor at non-linear load, which is the best result among circuits studied. This power transformer is resistant to load effects that distort voltage quality and is capable to provide a high level of symmetry and sinusoidal voltage as well as parallel operation with commercially available transformers. This makes it possible to use it in rural electrical networks to reduce power losses, increase service life and efficiency of electrical equipment, and increase reliability of the power supply system.

Выбор датчика излучения для систем контроля взрывопожароопасных объектов

This study justifies the selection of a radiation sensor for explosion and fire hazard monitoring systems. Preference is given to radiation sensors that perceive the energy of heated bodies, in this case a flame, and convert it into an electric signal. Since this energy is dissipated in the communication channel from the flame to the sensor and in the sensor itself, an analytical description of these losses and radiation energy in general is given, which is very important for assessing the sensitivity of the sensor. The following scheme of investigation of flame radiation energy is proposed. The source of radiation is stationary flame of various combustible substances, radiation energy of which is transmitted to the sensor through a fixed hole in a heat-tight screen in an air medium. The sensor is installed at a different distance from the flame, which makes it possible to detect the loss of radiation energy with distance. The sensor sensitive element is a metal bolometer OPB-4K, which receives infrared radiation flux amplified by a reflective mirror. Conversion of thermal radiation into electrical signal is performed by DC Bridge, to the arm of which the bolometer is connected. An amplifier is connected to a device setting threshold of sensor actuation. The threshold device, in turn, controls the thyristor switch, which allows turning on the power supply circuit of the actuator. The sensor operation is performed from individual power supply unit. The presented material is of great importance for the state service bodies in the field of fire safety and design organizations. It draws attention to the problem of improving automatic local means of explosion and fire protection.

Study of SEU Sensitivity of SRAM-Based Radiation Monitors in 65-nm CMOS

This article presents a static random access memory (SRAM)-based flexible radiation monitor. The monitor was fabricated in a 65-nm CMOS technology and it is designed as an application-specific integrated circuit, which comprises 768k bits SRAM cell matrix with individual power supply and a digital control core with a serial peripheral interface (SPI). By adjusting the core voltage of the SRAM matrix, the radiation sensitivity was made flexible. Also, SRAM cells with different threshold voltages were implemented to get further extension on tunable sensitivity range. The monitor has been tested under heavy ions with a linear energy transfer (LET) from 1.5 to 48.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text {MeV}\cdot \text {cm}^{2}$ </tex-math></inline-formula> /mg, high-energy (50–186 MeV) and low-energy (0.7–5 MeV) protons, and 14-MeV and thermal neutrons. An analysis was performed on how single-event upset sensitivity changes while tuning the supply voltage under different radiation environments. The results show that the monitor has the potential for space and facility applications.

SMART GRID TECHNOLOGY, TRANSMISSION OF ELECTRICAL ENERGY IN POWER SUPPLY AND LIGHTING SYSTEMS OF CITIES

Modern power supply and lighting systems of cities are complex electrical systems of an automated type, in which the processes in individual power supply systems and city lighting systems are interconnected and interdependent. Therefore, the search for efficient technologies for the transmission of electrical energy in them is an extremely difficult task. The real state of the power supply and lighting systems in cities today is characterized by low operating efficiency, largely due to the low quality of electrical energy and insufficient compensation of reactive power in them. The mutual influence of power supply and lighting systems in cities, as well as the presence of significant voltage deviations and the overflow of additional reactive power in the networks, causes an increase in voltage and power losses in them, as well as a decrease in the efficiency of networks and connected consumers, in general. Unfortunately, the existing methods and technical means based on them cannot fully solve this problem. The research carried out made it possible to clarify the nature of the processes in the power supply systems and the sanitation of cities and to determine the methods and technical means based on the Smart Grid concept. They are based on the use of phase-shifting booster transformers with an electronic control system. Their use made it possible to provide the possibility of complex control of the voltage modes of active and reactive power with the possibility of installation at any point in the network and centralized control from a single centre. The calculations show that the use of the developed methods and technical means provides an opportunity to reduce power losses in networks by 10–15% and energy costs for consumers by 50–75%.

Managing power supply interruptions: a bottom-up spatial (frontier) model with an application to a Spanish electricity network

In December 2013, a new electricity law was approved in Spain as part of an electricity market reform including a new remuneration scheme for distribution companies. This remuneration scheme was updated in December 2019, and the new regulatory framework introduced a series of relevant modifications that aim to encourage regulated firms to reduce their power supply interruptions using a benchmarking approach. While some managerial decisions can prevent electricity power supply interruptions, other managerial decisions are more oriented toward mitigating the consequences of these interruptions. This paper examines the second type of decision using a unique dataset referring to the power supply interruptions of a Spanish distribution company network between 2013 and 2019. We focus our analysis on the effect which grid automatization has on restoration times, the relative efficiency of the maintenance staff, and the importance of its location. We estimate a bottom-up spatial model and a stochastic frontier model to examine both external and internal power supply interruptions at municipal level. While our frontier model is standard, our spatial model differs from a conventional one in that it is developed from scratch using the information of each individual power supply interruption.

Continuous casting control via drive monitoring

The paper describes the investigation’s results of functional capabilities of the equipment testing systems as applied to the withdrawal roll drives provided with individual power supply using the frequency converter-asynchronous motor system. All the experimental investigations were carried out at the “Magnitogorsk Iron and Steel Works” (MISW). The statistical analysis of time diagrams and frequency-response curve of changes in instantaneous values of withdrawal roll drives load torques were used. The diagnostic signs of the withdrawal roll bending, occasional slippage along the slab, wear of ring seals, and teeth of the mounted gearbox on the basis of the analysis of the component range of spectrum density of changes in load torques were computed. It was found that variance inhomogeneity of scattering of load torque change for adjacent time intervals can be used as a diagnostic sign of the withdrawal roll occasional slippage along the slab. We considered the developed diagnostic methods for withdrawal roll drive equipment at continuous casting machines (CCMs) which provide the increase productivity due to decreasing of the CCM repair work downtime. A functional diagram and a generalized algorithm of the diagnostic system for equipment of the withdrawal roll were developed taking into account the characteristics of continuous casting of steel at a slab CCM. An experimental estimate was carried out to assess the efficiency of the developed diagnostic system.

Concept of a Universal Smart Machine with Protection against Spark Discharge

The concept of a universal device that can provide diagnostics and monitoring of individual and collective power supply systems, the construction of life support systems, the state of household appliances, the Internet of Things devices and housing and communal services devices is considered. This paper proposes new design solutions able to improve the existing technologies for assessment of the quality of the energy flow by two orders of magnitude in terms of overall characteristics relative to the existing analogues. The developed Smart microcontroller is designed to operate as an intelligent unit, to analyze the parameters of the AC voltage network and control the electromechanical elements of the Smart Circuit Breaker, as well as to send data through a standard interface. The implementation of protection against spark discharge is proposed. The proposed solution is based on the application of cloud and boundary computing technology. The possibilities for improvement of the efficiency of design technologies and construction of energy-efficient buildings, provision of the industry and households with a new type of information management services (monitoring energy infrastructure, etc.) are presented.

A group work of semiconductor resonant inverters of magnetically coupled induction systems

The paper presents the advantages of modular induction heating systems in the problems of group heating with individual power supply stations. When they are close to each other, a magnetic bond may occur between them. The paper shows the non-operability of power sources of magnetically coupled inductors. General principles of construction of noise-resistant magnetically coupled induction heating systems with individual power supply stations are given. A comparison and analysis of the stability of the power sources based on the current inverter and the voltage inverter has been carried out.

Sustainable energy systems in the digital economy: concept of smart machines

The concept of the creation of universal smart machines for power systems and critical infrastructure is discussed herein in terms of digital economy requirements. The functional requirements for a universal smart machine for sustainable energy systems are systematized based on a comparative analysis of technology. The requirements determine the approaches to the implementation of software, hardware and design solutions that provide diagnostics and monitoring of the energy state of infrastructures, systems for individual and collective power supply, life support systems of buildings, the state of household appliances, IoT devices, and devices of the housing and utilities sector. The recommendations on the constructive implementation of smart machines are given, making it possible to improve the existing approaches to quality assessment of the services provided in the energy industry. The concept of universal smart machines opens up the opportunities to increase the efficiency of providing the industry and households with a new type of information management services in the field of control over energy infrastructure as one of the main components of the digital economy.

Optimization model of power supply system of industrial enterprise

In this paper, the problem of optimizing the generated reactive power distribution for reducing the loss of active power in the elements of industry power supply system presented. The problem of optimal distribution of generated reactive powers by synchronous motors in the power supply systems belongs to the nonlinear mathematical programming class and can be solved by using the Lagrange multiplier method. The Lagrange method allows one to reduce the problem of conditional optimization (that is, finding the relative extremum of the objective function with certain limitations) to the simpler problem of unconditional optimization (the search of an absolute extremum).A complete mathematical model of optimization problem of the rational distribution of the generated reactive power by the synchronous motors in order to reduce the loss of active power in the power supply system elements of an industrial enterprise developed. The obtained mathematical problem allows one to consider a number of limitations related to both the mode of operation for the individual power supply system elements and the entire system as it is.

The Wendelstein 7-X trim coil system commissioning and first operational results

The magnet system of the stellarator fusion device Wendelstein 7-X (W7-X) is composed of three different groups of coil systems. The main magnetic field is created by a superconducting magnet system that is accompanied by two sets of normal conducting coil groups, the Control Coils inside the plasma vessel and the Trim Coils (TC) positioned outside of the cryostat.The TC system consists of five coils, power supplies, cooling systems, high current connections and superordinated control systems for autonomous remote control. There are four coils (type A) of equal shape; the fifth coil (type B) has a slightly different shape due to space restrictions at the assembly position. Five individual power supply units whose design is based on four-quadrant current converters using Insulated-Gate-Bipolar-Transistors power the TC with individual currents and ramp rates. This allows the correction of error fields and also increases the experimental flexibility by providing a means to balance the divertor heat loads among the five field periods.The TC with its instrumentation and the power supplies including the switchgear to be connected to the coils have been designed and build in collaboration between IPP, Germany and PPPL, USA, funded by the Department of Energy. The design and integration of all auxiliary systems like the grid station, cooling for coils and powers supplies, control system and the associated cabling and piping has been developed, manufactured and accomplished in 2014.This paper describes the results obtained during the integral commissioning of the TC system, the operational experiences during the first experimental campaign of W7-X and its impact on the physics program.

Design and performance of high voltage power supply with crowbar protection for 3-Φ high power rf amplifier system of cyclotron

The superconducting cyclotron at VECC consists of three rf cavities separated at 120° and each cavity is fed power from an individual rf amplifier, based on a tetrode tube, in the frequency range of 9–27 MHz. All the three tetrode tubes are powered by individual power supplies for their biasing which are fabricated and commissioned with the rf system of the cyclotron. The dc power to the anodes of all three tubes is fed from a high voltage power supply rated at 20 kV dc, 22 A along with suitable interlocks and crowbar protection. The tubes are protected by a single ignitron based crowbar system against an internal arc fault by diverting the stored energy very fast, minimizing the deposited amount of energy at load and allowing the fault to clear. The performance and protective capability of the crowbar system is demonstrated by using wire survivability test. The design criteria of anode power supply along with the crowbar protection system, in-house development, testing and performance is presented in this paper.

Power Supply System for Corrector Magnets of the European X-Ray Free-electron Laser

The total length of the European XFEL is 3.4 km. The electron beam parameters are corrected by about 300 corrector magnets, each powered by an individual power supply. BINP performed the development, production and delivery of the power supply system for the corrector magnets. For the powering of the corrector magnets, seven types of precision power supplies with output currents of up to 10 A and output voltages of up to 70 V were developed. To ensure high reliability of the power supply system BINP developed a “redundancy” system, which enables remote replacement of a faulty power supply with a spare one.

Power supply system for KSTAR neutral beam injector

The power supply system in KSTAR neutral beam injector consists of low voltage and high current DC power supplies for plasma generator of ion source and high voltage and high current DC power supply for accelerator grid system. The arc discharge is initiated by an arc power supply supplying the arc voltage between the chamber wall and 12 filaments which are heated by individual filament power supply. The negative output of arc power supply is common to each positive output of 12 filament power supplies. To interrupt the arc discharging for the fault condition of the arc current unbalance, DCCT current monitor is placed at the positive output cable of the filament power supply. The plasma grid (G1) power supply has the maximum capability of 120kV/70A which consists of low voltage regulator with IGBT-switched chopper array system for the voltage control in unit of 600V and the high voltage rectified transformers to supply DC voltage of 20kV, 30kV, and 50kV. The output voltage of the G1 power supply is also connected to the input of the voltage divider system which supplies the gradient voltage to the gradient grid (G2) in the range of 80–90% of G1 voltage by changing tap of winding resistors in unit of 1%. The charged G1 voltage is turned on and off by the high voltage switch (HVS) system consisting of MOSFET fast semiconductor switches which can immediately be opened less than 1μs when the ion source grid breakdown occurs. The decelerating grid (G3) power supply is inverter system using capacitor-charge power supply to supply maximum −5kV/5A. The important component in power supply system is the surge absorber near the ion source to limit the arc energy deposited to accelerator grid. This paper presents configuration and features of power supply system, main controller, and interlock system of KSTAR NBI.

Radial Lorentz force augmented deep drawing for large drawing ratio using a novel dual-coil electromagnetic forming system

In order to overcome the limitations of the existing electromagnetic forming systems for deep drawing, a dual-coil system has been developed for deep drawing of sheet metal with large drawing ratio. In addition to the conventional driving coil that generates the axial Lorentz force on the workpiece, a radial inward force in the flange region is generated by a second coil that is energized by an individual power supply. The axial force pushes the sheet into the die in axial direction, while the radial Lorentz force enhances the material flow of the flange. The effectiveness of the novel system is validated by a series of experiments for deep drawing a cup of AA1060-H24 with drawing ratio of 3.25. It is demonstrated that with the dual-coil system the material flow of the flange can be significantly enhanced, and the maximum forming depth without failure is greatly increased from 8.44mm to 20.28mm. The new electromagnetic forming method is expected to break through the bottleneck of deep drawing and enable major advances in forming metallic parts and components that are difficult to form, by developing driving coils with advanced design.

Energy Cooperation in Cellular Networks with Renewable Powered Base Stations

In this paper, we propose a model for energy cooperation between cellular base stations (BSs) with individual hybrid power supplies (including both the conventional grid and renewable energy sources), limited energy storages, and connected by resistive power lines for energy sharing. When the renewable energy profile and energy demand profile at all BSs are deterministic or known ahead of time, we show that the optimal energy cooperation policy for the BSs can be found by solving a linear program. We show the benefits of energy cooperation in this regime. When the renewable energy and demand profiles are stochastic and only causally known at the BSs, we propose an online energy cooperation algorithm and show the optimality properties of this algorithm under certain conditions. Furthermore, the energy-saving performances of the developed offline and online algorithms are compared by simulations, and the effect of the availability of energy state information (ESI) on the performance gains of the BSs' energy cooperation is investigated. Finally, we propose a hybrid algorithm that can incorporate offline information about the energy profiles, but operates in an online manner.

A magnetic-field transducer based on a magnetic-field-controlled electrochemical cell

An electrochemical cell in which the electrolyte is a ferromagnetic suspension of a specific composition containing acidic electrolytic components was proposed for use as a transducer for the indication of magnetic fields. The voltage that forms at cell electrodes is due to changes of the suspension properties, which are induced by a magnetic field applied to the suspension. The dependence of the voltage on the electrolytic component percentage was studied and its increase was shown to increase the field sensitivity of the indicator; however, the sensitivity becomes nonlinear. The transducer can be used for the indication of both uniform and nonuniform magnetic fields produced by various sources. The absence of an individual power supply and simplicity are advantages of the transducer over previously used ones.