Large Electric Power Research Articles

Complementary Multisite Turnover Catalysis toward Superefficient Bifunctional Seawater Splitting at Ampere-Level Current Density.

The utilization of seawater for hydrogen production via water splitting is increasingly recognized as a promising avenue for the future. The key dilemma for seawater electrolysis is the incompatibility of superior hydrogen- and oxygen-evolving activities at ampere-scale current densities for both cathodic and anodic catalysts, thus leading to large electric power consumption of overall seawater splitting. Here, in situ construction of Fe4N/Co3N/MoO2 heterostructure arrays anchoring on metallic nickel nitride surface with multilevel collaborative catalytic interfaces and abundant multifunctional metal sites is reported, which serves as a robust bifunctional catalyst for alkaline freshwater/seawater splitting at ampere-level current density. Operando Raman and X-ray photoelectron spectroscopic studies combined with density functional theory calculations corroborate that Mo and Co/Fe sites situated on the Fe4N/Co3N/MoO2 multilevel interfaces optimize the reaction pathway and coordination environment to enhance water adsorption/dissociation, hydrogen adsorption, and oxygen-containing intermediate adsorption, thus cooperatively expediting hydrogen/oxygen evolution reactions in base. Inspiringly, this electrocatalyst can substantially ameliorate overall freshwater/seawater splitting at 1000mA cm-2 with low cell voltages of 1.65/1.69V, along with superb long-term stability at 500-1500mA cm-2 for over 200 h, outperforming nearly all the ever-reported non-noble electrocatalysts for freshwater/seawater electrolysis. This work offers a viable approach to design high-performance bifunctional catalysts for seawater splitting.

Increased Load Power With Centralized Control of Multiple Microgrid Resources

There are many rural areas on remote islands that cannot be reached by electricity sources from the utility grid. However, Indonesia is a country that has an abundant supply of renewable energy. One of the renewable energies that is obtained for free is solar energy sources. Renewable energy has great potential as a source of distributed electricity generation or microgrids. This article proposes a new method for providing large electrical power supplies for rural areas, namely multiple microgrids with a centralized control strategy. The purpose of this method is to provide stability of power supply to the load. In this method, each microgrid has solar panels (SP), batteries, and diesel generators (GD). Multiple microgrids provide power supply to DC loads and AC loads. The centralized controller uses an outseal programmable logic controller (PLC) which functions to regulate the power flow of microgrid 1 (MG1), microgrid 2 (MG2), and microgrid 3 (MG3) to the load alternately. Simulation test results show the performance of a centralized control which is able to provide power supply to the load according to demand or changes in load. Power regulation management for rural areas can be developed for large-scale microgrid systems. Keywords: multiple-microgrid; centralized control; solar panel

Reengineering of technological business processes of a generating energy company in modern conditions

The article studies the improvement of the production activities of a large electric power company in the Moscow region, Public joint stock company “Mosenergo” (hereinafter referred to as “Mosenergo”) by proposing a set of measures for a radical renovation (reengineering) of the main technological business process – “Heat and electricity production”. Based on the process approach and methods of strategic analysis, SWOT (strengths, weaknesses, opportunities, threats), the key company success factors were identified, an enlarged business model of “Mosenergo” was built and analysed, followed by the selection of the most preferable business process. With the help of a matrix of criteria, an assessment of business process importance or readiness for the implementation of the selected strategies was made. Key success factors for “Production of heat and electricity” business process were formed. However, in modern conditions, due to the tightening of sanctions imposed by unfriendly countries, the risks of supply disruptions and termination of equipment maintenance are increasing, which causes negative trends in key performance indicators of the selected business process, namely the accident rate and/or the frequency of emergency operation of automatics cases. The set of measures for reengineering the business process “Production of heat and electricity” is based on the idea of automatic technological business process of the company through the introduction of highly effective domestic digital technologies as part of the industry’s digital transformation strategy. The import substitution programme to minimise risks caused by geopolitical events in the world is considered.

High Thermoelectric Power Factors in Plastic/Ductile Bulk SnSe2 -Based Crystals.

The recently discovered plastic/ductile inorganic thermoelectric (TE) materials open a new avenue for the fabrication of high-efficiently flexible TE devices, which can utilize the small temperature difference between human body and environment to generate electricity. However, the maximum power factor (PF) of current plastic/ductile TE materials is usually around or less than 10 µW cm-1 K-2 , much lower than the classic brittle TE materials. In this work, a record-high PF of 18.0 µW cm-1 K-2 at 375 K in plastic/ductile bulk SnSe2 -based crystals is reported, superior to all the plastic inorganic TE materials and flexible organic TE materials reported before. The origin of such high PF is from the modulation of material's stacking forms and polymorph crystal structures via simultaneously doping Cl/Br at Se-site and intercalating Cu inside the van der Waals gap, leading to the significantly enhanced carrier concentrations and mobilities. An in-plane fully flexible TE device made of the plastic/ductile SnSe2 -based crystals is successfully developed to show a record-high normalized maximum power density to 0.18W m-1 under a temperature difference of 30 K. This work indicates that the plastic/ductile material can realize high TE power factor to achieve large output electric power density in flexible TE technology.

Methodological Proposal: First Steps for the Implementation of Demand Management Programs in Colombia

The electrification of isolated or rural areas brings with it technical, economic, and social challenges that differentiate the operation of these networks compared to the traditional operation of large electrical power systems, such as the dependence of air or river transport on fuel for the supply of generation plants, the absence of individual measurement and the obsolete infrastructure of the distribution networks. Therefore, this paper proposes a hybrid methodology for studying a Colombian case, analyzing the development of programs for rational electricity use and energy efficiency in isolated areas. These first steps are related to the diagnosis of the current conditions of the power network, the identification of actors that can influence the regulation of the electricity service in the area, and the proposal of mechanisms that allow promoting the rational and efficient use of the electricity.

ANALISIS SUDUT SERANG TERHADAP KARAKTERISTIK AERODINAMIKA PADA BILAH 4412 RPM RENDAH DENGAN METODE CFD 6DOF

At this time the power plant still uses a lot of coal fuel, so it is necessary to look for alternative energy, one of which is wind energy. Wind turbines are devices that can convert kinetic energy in the wind into mechanical energy which is then converted into electrical energy through a generator. The analysis method in this research uses Computational Fluid Dynamics (CFD), Qblade, and experimental validation testing using a wind tunnel. The simulated airfoil types consist of 3 types, namely, NACA 4412, NACA 4415, and FX-60 100 (126). The simulation results show that, the most optimal airfoil is NACA 4412 with an angle of attack of 25° and a wind speed of 8 m/s can produce a torque of 3.55503 Nm, a pressure of 45 Pa, a tangential velocity of 55.495 m/s, and a rotational speed of 529. 94 rpm, while the smallest simulation results are on the FX-60 100 (126) airfoil with an angle of attack of 15° and the same wind speed of 8m/s can produce a torque of 1.60390 Nm, a pressure of 40 Pa, a tangential velocity of 9.06592 m/s, and a rotational speed of 108.2164 rpm. The results of experimental testing of wind turbines where the wind turbine used uses the geometry of NACA 4412 show that an angle of attack of 25 ° and a wind speed of 8m / s produces a large electrical power and rpm with a value of 7.98 Watt and 482.2 rpm respectively

Three-dimensional motion control of an untethered magnetic object using three rotating permanent magnets

Magnetic motion control has been actively studied mainly for the purpose of biomedical applications. However, in many cases, many actuator magnets surround a small magnet to be moved, and they consume large electric power. In some cases, complex calculations are required to estimate the control input of the actuator magnets. This study proposes a simple method to move a small magnet to the desired positions. For this, three cylindrical permanent magnets magnetized in the radial direction were positioned as the sides of a triangle; these actuator magnets were rotated using motors. By monitoring the position of the small magnet and through simple feedback control based on the angles of the three actuator magnets, the untethered small magnet could be moved along arbitrary three-dimensional (3D) paths. The control principle was established by calculating the magnetic force and torque acting on the small magnet for some sets of actuator-magnet angles.

Modeling and Simulating Wind Energy Generation Systems by Means of Co-Simulation Techniques

This paper presents the development of a wind energy conversion system co-simulation based on the Functional Mock-up Interface standard aiming at contributing to the development of co-simulation of large electrical power systems by means of open-source and standardized computational tools. Co-simulation enables the computational burden of a monolithic simulation to be shared among several processing units, significantly reducing processing time. Through the Functional Mock-up Interface standard, developed models are encapsulated into Functional Mock-up Unit, providing an extra means for the protection of intellectual property, a very appealing feature for end users, both in industry and academia. To achieve the decoupling of the subsystems, the Bergeron ideal transmission line model will be used, with travel time equal to the simulation time-step. The computational performance and effectiveness of the proposed co-simulation technique was evaluated with a wind power plant with 50 wind turbines. The system digital models were developed into Modelica language, while co-simulation was implemented in Python.

Dual-boost thermoelectric power generation in a GeTe/Mg3Sb2-based module

Studies on thermoelectric materials have been primarily centred on conversion efficiency, as if to assert a high-efficiency thermoelectric module always generates a large electrical power. However, there is a trade-off between conversion efficiency and power density under thermal and electrical energy losses due to contact resistances at electrode junctions. Thus, simultaneously boosting the power density and conversion efficiency (‘dual-boost’) is essential. Here, to overcome the trade-off by minimizing energy losses, we focus on two approaches for p-type GeTe- and n-type Mg3Sb2-based thermoelectric materials. First approach is to reduce thermal conductivity of GeTe by inducing a strong phonon scattering and tuning the hole concentration. Second approach is to reduce electrical contact resistivities of GeTe and Mg3Sb2 by optimizing highly conductive electrode junctions. As a result, we achieve a record-high dual-boost performance (1.94 W/cm2 and 10.1%) in a practical-size module. The result will advance thermoelectric generator technology for widespread applications.

Development of a powerful miniature hydrogen catalytic combustion powered thermoelectric generator

Rapid development of portable electronics promotes the R&D of micro/miniature power sources with high energy density. The high mass energy density and zero emission characteristic of hydrogen show a huge potential to develop powerful portable hydrogen-based power sources. A miniature hydrogen catalytic combustion powered thermoelectric generator (CCP-TEG) is designed and tested in detail. An outstanding catalytic core is prepared with a newly proposed method on the basis of combining H2PtCl6 solution and foamed transition metal. Such catalytic core is demonstrated to provide high combustion temperature, complete combustion, and sufficient heat flux for power generation. Several parameters including input power, equivalent ratio, cooling mode, and load resistance are investigated to clarify their influences on the combustion temperature, electric power, and various efficiencies (combustion, heat collection, TE, and overall efficiencies) of the hydrogen CCP-TEG. The developed hydrogen CCP-TEG is able to generate an electric power of 20.7 W with an overall efficiency of 2.04%, filling the research gap of generating large electric power (>10 W) with sufficiently high overall efficiency (>2%) in the research field of hydrogen CCP-TEG. The generated electric power and overall efficiency are much higher than those in previous hydrogen CCP-TEGs. The prepared catalytic core remains excellent functionality after running for 30 h, and the combustion temperature is as high as 918 K, which ensures the sufficiently high temperature difference for powerful power generation. This study is conducted to illustrate a concrete method on developing a powerful hydrogen CCP-TEG, and to identify further research directions.

Simulating a Strong Magnetic Storm Impact on Russia’s Interconnected Power System of Center

Studying of a negative impact of the space weather and magnetic storms as its special case, on the performance of a critical technological infrastructure, with development of methods and means for protecting it is a relevant but difficult task. Many advanced countries, primarily the United States, are dealing with this problem. The article presents the results of elaborating a methodology for computational simulation of the impact of geomagnetically induced currents on large electric power systems. The developed methodology makes it possible to take into account the influence of changes in the reactive power and temperature of power transformer structural elements caused by magnetic biasing of their core, as well as the operation of relay protection. The impact of the geomagnetically induced currents expected during a strong magnetic storm on Russia’s Interconnected Power System of Center, including the power systems of Moscow, Leningrad and other major administrative and industrial regions of the country has been simulated for the first time. It is shown that such impact gives rise to a set of factors that can cause the development of a system-wide accident: a significant decrease in voltage at a number of power system facilities, mass-scale disconnection of power lines by their relay protections, and unacceptable heating of structural elements of some power transformers.

Electrical Event Detection and Monitoring Data Storage from Wide Area Measurement System

Synchronized phasor measurement systems are being widely used around the world and have become essential elements in the evolution of the operation of large electrical power systems (EPS). These systems, called Phasor Measurement Units (PMUs), are capable of recording and communicating dynamic data from the EPSs in a synchronized way by GPS and with a high sampling rate, generate a huge set of data that, among many applications, has the capacity to detect events. In this way, this work presents a data management system architecture applied to a real PMU system located in the state of Paraná, Brazil that detects and storages events using principal component analysis and Pearson correlation. This method can detect and store electrical events that occurred during the operation of the national interconnected system of Brazil with good results.

Passive thermal control of a triple-junction solar cell at high concentrations using various finned heat sink configurations

Designing an effective heat sink that is light, inexpensive, and simple to manufacture and install, is crucial in developing a heat control strategy for high concentrated triple-junction (TJ) solar cells to maintain the cell operating temperature below the maximum allowed limit. Such heat sinks ensure better electrical output power and efficiency at a cheaper cost. Thus, the present research focuses on the passive thermal regulation of a triple-junction solar cell utilizing four different finned heat sink configurations; (A) flat plate, (B) straight fins, (C) pin fins, and (D) flared fins heat sink. A comprehensive 3D thermal and electrical model is developed and computationally simulated, incorporating the cell module layers coupled with the aluminium heat sink. The performance of the proposed system with different heat sink designs is investigated at various concentration ratios (CR) of the solar irradiance ranging from 50 suns to 1250 suns, air temperatures ranging from 25 °C to 40 °C, and wind speeds ranging from 1 m/s to 5 m/s. In hot climatic conditions (40 °C and 1 m/s), the integration of the proposed heat sink configurations A, B, C, and D enables the cell to operate safely (below 110 °C) at high concentration ratios of 440 suns, 1435 suns, 1250 suns, and 1775 suns, respectively, and produce large electric power of 15.2 W/cm2, 49.7 W/cm2, 43.3 W/cm2, and 61.4 W/cm2. In contrast, the maximum permissible concentration ratio of an uncooled cell operating in the same conditions is limited to 77 suns with an electrical output of 2.7 W/cm2. Although the flared fins heat sink is the heaviest, weighing about 0.6 kg, and the flat plate one is the lightest with 0.05 kg, the environmental analysis revealed that utilizing the former for cooling concentrated photovoltaic systems could reduce annual CO2 emissions by 1475.2 tons/m2 compared to 364.5 tons/m2 for the latter if both are operated at the maximum permissible solar concentration ratio.

Speed/Torque Ripple Reduction of High-Speed Permanent Magnet Starters/Generators With Low Inductance for More Electric Aircraft Applications

With the electrification trend of future aircraft, high-speed permanent magnet starters/generators (PMSs/Gs) will potentially be widely used in onboard generation systems due to their high power density and high efficiency. However, the per-unit reactance of such high-speed machines is normally designed to be very low due to limited onboard power supply voltage and large electrical power demand, which can result in large current ripples in the machine and thus large torque ripples especially when the machine is fed with a semiconductor-based inverter of a lower switching frequency. The torque ripples may further lead to speed oscillation and generate severe vibrations and noises that are harmful to the mechanical system and human beings around. In this article, a speed/torque ripple reduction method for high-speed PMS/Gs with a low inductance is proposed to improve their performance within a wide speed range. An active damping technique is applied to the speed loop to increase the anti-disturbance capability and generate a smoother reference for the current loop, whereas an adaptive output voltage saturation limit is utilized for the current loop to limit the peak value of current to prevent overcurrent and torque spikes. The parameter tuning criteria are derived through a thorough analysis. Finally, the proposed method is validated on a high-speed PMS/G with an inductance of 99 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{H}$ </tex-math></inline-formula> . The results show that the speed ripples and torque ripples are reduced by over 50% within a speed range of 2–14 krpm.

Development of Si Power ICs and Evolution to SiC Large Electric Capacity Power ICs

Development of Si Power ICs and Evolution to SiC Large Electric Capacity Power ICs

Qualitative Analysis of Enterprise Risk Management Systems in the Largest European Electric Power Companies

Enterprise risk management (ERM) is an important element of an efficient and comprehensive corporate governance system. It represents a combination of activities that minimise the negative impacts of the risk exposures on the company’s value and long-term corporate sustainability. Recently, there has been a growing awareness on the role and importance of the risk management function. Such trends are partly driven by the consequences of the last economic and financial crisis on the one hand, and on the other by legal and regulatory requirements. The economic downturn caused by the COVID-19 pandemic, volatility in the energy markets and increased uncertainty expected in the upcoming period reiterate the importance of timely risk management practices, because organisations with developed risk management systems are more resilient in case of crisis. This paper analyses the organisation and level of development of ERM systems in the ten largest European electric power companies. The companies’ data on risk management practices are collected from annual reports and analysed by applying Content Analysis (CA), searching for 29 characteristics of a developed ERM system. Research results reveal that ERM in the largest EU electric power companies can be considered as advanced as it applies the five dimensions of the COSO 2017 framework. The analysis confirms the existence of 27 out of 29 characteristics of a developed ERM system, confirming that these characteristics are rooted not only in the relevant ERM theory, but also in the practice of large and successful electric power companies.

Cyber security challenges in the electric vehicle infrastructure

The number of electric vehicles (EVS) and charge points in Europe is growing rapidly. These charge points are all ‘connected’ and collectively represent a very large electric power demand. In order to prevent overloading of the electricity grid at certain times and locations, and to properly align the charging of EVs with the availability and price of renewable energy, Smart Charging is or will be applied. Charging points are then controlled remotely from a back office. Home charging points can be connected to a home energy management system which in turn is connected to a central system. Good cyber security is therefore crucial for the stability of the electricity grid. If the cyber security of charge points is not well managed, it is a potential risk to the stability and security of the public electricity grid. A hack of a large number of charge points could cause damage on two levels: A disruption of the national system balance. If a hacker were to suddenly switch off a very large number of charge points, the question is whether the TSO, would be able to adapt production capacity and/or demand quickly enough. If this is not successful, a national blackout could be the result. At a switchable power capacity of 3 GW, the stability of the entire European electricity grid could be at risk. Local overloading of the distribution grid. If the regional grid operator uses smart charging to tailor charging to the maximum grid capacity and a hacker were to override those control signals, components in the power grid such as cables or transformer stations could be overloaded and, in extreme cases, catch fire. To ensure good cyber security of charge points, international standards must be agreed upon both for the charge points and the back-office systems. Also, a legal framework must be created at EU-level to ensure implementation and quick countermeasures in case of cyber security incidents and infringements.

Modeling of wind turbine based on dual DFIG generators

In order to investigate a viable approach to fully exploit the wind speed, the present work investigates the application of a novel wind turbine consisting of dual doubly-fed induction generators (DFIG). The model can be further used to apply in areas where the winds are high to achieve high conversion efficiency in order to produce large electric power and increase the wind turbine capacity with an economy of hardware on the one hand, and to reduce the installation cost on the other. Furthermore, this model is always guarantees the continuity of power production because if one generator fails, the second generator will keep working until the broken one is repaired. The proposed model of the wind turbine based on dual doubly-fed induction generators (WT-dual-DFIG) were using the indirect field-oriented control (IFOC) was validated by wind turbine based on single doubly-fed induction generator (WT-single-DFIG) in MATLAB/Simulink. The results of simulation show that the simulated responses of the WT-dual-DFIG increased the power by a factor of about 14.3% compared to a WT-single-DFIG due to the use of a variable speed dual-DFIG. Finally, we can say that the WT-dual-DFIG model is strongly developed and could be applied in the coming years.

მსხვილი ელექტროენერგეტიკული კომპანიის ფინანსური მდგრადობის შეფასების ოპტიმალური ეკონომეტრიკული მოდელის შემუშავება და მისი პროგნოზული აპრობაცია საქართველოში

An optimal econometric model for assessing the financial stability of a large electric power company has been developed based on the in-depth analysis, which takes into account all possible factors affecting financial stability. The types of factors are established by correlation analysis. The model is universal in nature, its application is possible in assessing the financial stability of any enterprise. For the purpose of practical implementation of the optimal econometric model for assessing financial stability, a predictive approbation was carried out using the example of the Georgian State Electricity System and JSC Telasi. As a result, problems in the management of financial stability were identified and ways to solve them were outlined.

Intelligent Supply Chain Management Modules Enabling Advanced Manufacturing for the Electric‐Mechanical Equipment Industry

Electric‐mechanical equipment manufacturing industries focus on the implementation of intelligent manufacturing systems in order to enhance customer services for highly customized machines with high‐profit margins such as electric power transformers. Intelligent manufacturing consists in using supply chain data that are integrated for smart decision making during the production life cycle. This research, in cooperation with a large electric power transformer manufacturer, provides an overview of critical intelligent manufacturing (IM) technologies. An ontology schema forms the terminology relationships needed to build two intelligent supply chain management (SCM) modules for the IM system demonstration. The two core modules proposed in this research are the intelligent supplier selection and component ordering module and the product quality prediction module. The intelligent supplier selection and component ordering module dispatches orders that match the best options of suppliers based on combined analytic hierarchy process (AHP) analysis and multiobjective integer optimization. In the case study, the intelligent supplier selection and component ordering module demonstrates several acceptable Pareto solutions based on strict constraints, which is a very challenging task for decision makers without assistance. The second module is the product quality prediction module which uses multivariate regression and ARIMA to predict the quality of the finished products. Results show that the R square values are very close to 1. The module shortens the time for the company to accurately judge whether the two semifinished iron cores for the product meet the quality requirements. The component supplier selection module and the finished product quality prediction module developed in this research can be extended to other IM systems for general high‐end equipment manufacturers using mass customization.