Hasil untuk "Production of electric energy or power. Powerplants. Central stations"

Xiaoping FENG, Qidi CHEN, Qingchun ZHAO et al.

Under the dual carbon target, a large number of new energy sources are connected to the power grid, and relay protection is becoming increasingly important as the primary guarantee for the safe and stable operation of the power system. The research on grid type inverter technology mainly focuses on system stability control, fault ride through, and other aspects, with little attention paid to the characteristics of relay protection. In this regard, this article analyzes the adaptability of transmission line protection under the control strategy of grid type energy storage inverters. Firstly, the synchronous control strategy and fault ride-through control strategy of grid-forming converters are analyzed, with equivalent circuits derived for grid-forming converters under different fault ride-through control strategies in the event of faults. Secondly, an evaluation of the operational performance under grid-forming control strategies is conducted. Additionally, an adaptability analysis is performed for each of these protection configurations. Lastly, a transmission line model incorporating a grid-forming energy storage converter is established in Simulink to validate the relevant theories. Based on the adaptability of transmission line protection, corresponding improvement suggestions are proposed.

Tianyu Xing, Lingfeng Gao, Peiyu Yin et al.

This paper proposes an A-shape hybrid levitation system combining high-temperature superconducting (HTS) maglev and permanent magnet levitation (PML) technologies to address the lateral instability of the PML system. By tilting the PM arrays and HTS bulks on both sides at a specific angle, the system’s cross-section forms an “A” shape. This configuration offers dual advantages: the A-shape PML significantly mitigates unstable lateral deflection forces while preserving levitation capacity, whereas the A-shape HTS maglev enhances guidance force. Through systematic analysis, the effects of the tilt angle and the magnetization direction of the PM arrays on levitation performance are investigated and optimized. The simulation results demonstrate that, at the lateral movement of 5 mm, for the PML system, a tilt angle of 45° reduces lateral deflection force by 94.4%, and synergistic optimization of the tilt angle of 40° and magnetization direction of 38° achieves an 84.6% reduction. The HTS maglev system enhances guidance force, with a 45.3% improvement at a 60° tilt angle and a 30° magnetization direction. This study presents a promising solution for developing a stable, high-load-capacity hybrid levitation system.

Xianming Sun, Yuhang Yang, Changzheng Chen et al.

Rolling bearings, as critical components of rotating machinery, directly affect the reliability and efficiency of the system. Due to extended operation under high load, harsh environmental conditions, and continuous use, bearings become more susceptible to failure, leading to a higher likelihood of malfunction. To prevent sudden failures, reduce downtime, and optimize maintenance strategies, early and accurate diagnosis of rolling bearing faults is essential. Although existing methods have achieved certain success in processing acoustic and vibration signals, they still face challenges such as insufficient feature fusion, inflexible weight allocation, lack of effective feature selection mechanisms, and low computational efficiency. To address these challenges, we propose a dynamic weighted multimodal fault diagnosis model based on the fusion of acoustic and vibration information. This model aims to enhance feature fusion, dynamically adapt to signal characteristics, optimize feature selection, and reduce computational complexity. The model incorporates an adaptive fusion method based on a multi-branch convolutional structure, enabling unified processing of both acoustic and vibration signals. At the same time, a cross-modal dynamic weighted fusion mechanism is employed, allowing the real-time adjustment of weight distribution based on signal characteristics. By utilizing an attention mechanism for dynamic feature selection and weighting, the robustness of classification is further improved. Additionally, when processing acoustic signals, a depthwise separable convolutional network is used, effectively reducing computational complexity. Experimental results demonstrate that our method significantly outperforms other algorithms in terms of convergence speed and final performance. Additionally, the accuracy curve during training showed minimal fluctuation, reflecting higher robustness. The model achieved over 99% diagnostic accuracy under all signal-to-noise ratio (SNR) conditions, showcasing exceptional robustness and noise resistance in both noisy and high-SNR environments. Furthermore, its superiority across different data scales, especially in small-sample learning and stability, highlights its strong generalization capability.

Souad Bezzaoucha Rebai

Nonlinear robotic systems often operate under widely varying conditions that challenge traditional linear control approaches. The Linear Parameter-Varying (LPV) paradigm overcomes these limitations and offers a unifying framework by representing the system’s time-varying dynamics as a convex blend of linear models. This enables both controller and observer synthesis through convex optimization, while considering nonlinearities and time-dependent behavior. This paper presents a linear matrix inequality (LMI)-based methodology for simultaneous stabilization control and state estimation in robotic application within the LPV/polytopic setting. Parallel to controller design, the full-state estimation challenge posed by limited sensors in robotics is addressed. An LPV observer architecture, based on the Luemberger observer, is proposed. The simultaneous observer/controller gains synthesis is then reduced to an LMI feasibility problem. The efficacy of our approach is then demonstrated and illustrated through simulations.

Tuo Zhao, Luyao Wang, Chu Zhang et al.

Abstract The controversies about the mechanism of sodium storage in hard carbon (HC) hinder its rational structural design. A series of porous HC materials using coal tar pitch show a reversible capacity of 377 mAh g−1 and an initial Coulombic efficiency (ICE) of 87% as well as excellent cycling performance. More attention is paid to exploration of the relationships between the sodium status on various storage sites at different sodiation states and the ICE by solid‐state 23Na nuclear magnetic resonance spectroscopy. The adsorbed Na ions contribute the most to the irreversible capacity. The de‐solvated Na ions entering the closed pores are reduced to Na atoms and aggregated to Na clusters. Also, this process contributes the most to the reversible capacity and is characteristic of a long plateau in the voltage profile. Intercalation is partially reversible; it is the main source of capacity for slope‐type HCs but plays a minor role in the reversible capacity of plateau‐type HCs. Therefore, increasing the content of the closed pores can improve the reversible plateau capacity and reducing the open mesopores of HC increases the ICE. These findings provide insights into the structural design and cost‐efficient preparation of high‐performance HC anode materials for advanced sodium‐ion batteries.

Zeshan Abbas, Hafiza Yousra Bibi, Usman Khalid et al.

Microbial fuel cells (MFCs) have potential in wastewater treatment, biogas production and clean energy generation. MFCs provide an interdisciplinary research approach incorporating engineering and natural sciences. This study explores MFCs’ capabilities to produce electricity and biogas from wastewater and field soil substrates with different compositions. A two-chamber MFC system was operated anaerobically. Household sewage water used as the organic substrate with different soil amounts. Six different process feed compositions, labeled MFC-1–6, were investigated. MFC-1 exhibited the highest biogas generation volume of 245 cm³ and 42 mW/cm² power density. MFC-5 and −6 yielded 100 cm³ and 130 cm³, respectively. Wastewater treatment was effective on day 20, with pH, conductivity, turbidity, and total dissolved solids decreased to 7.3, 2.6 mS, 326 NTUs, and 1114 mg/L, respectively. Since, MFC-1 autonomously generated −800 mV, an external battery supplied an additional 600 mV to meet the methane generation voltage requirements. MFCs’ effectiveness in addressing wastewater treatment and renewable energy production was highlighted.

Zhilei Yao, Yiming Zhang

Misalignment of the secondary coil relative to the primary coil is inevitable in the wireless power transfer (WPT) converter, which decreases the transmission power and the system efficiency. Moreover, constant current (CC) and constant voltage (CV) control methods should be used to improve the charging efficiency of the battery. Thus, a WPT system based on TS/S-SP (T-order series/series − series and parallel compensation) hybrid compensation network is proposed. The system can transfer between the CC mode and the CV mode by controlling two switches. The CC and CV modes can be realized by the TS-SP and S-SP compensation networks. Operating principles of the proposed converter in both modes are elaborated. The misalignment tolerant ability is compared with other existing resonance networks. Finally, the theoretical analysis is confirmed by simulation and experimental results. When longitudinal axis misalignment of the coupler changes by 1/5, the output voltage fluctuation in the CV mode is only 1.06 % under Z- misalignment and 2.5 % under Y- misalignment. The output current fluctuation in the CC mode is 4.7 % under Z- misalignment and 4.53 % under Y- misalignment. Efficiency of the WPT converter is above 90 % in both CC and CV modes. The seamless transfer can be achieved from CC to CV modes.

Phillip Scherzl, Michael Kaupp, Wassima El Mofid et al.

Conventionally, cathode current collectors for lithium-ion batteries (LIB) consist of an aluminum foil generally manufactured by a rolling process. In the present work, a novel one-step manufacturing method of structured aluminum foil current collectors for lithium-ion batteries by electroforming is introduced. For this, a low-temperature chloride-based ionic liquid was used as an electrolyte and a rotating cylinder out of stainless steel as a temporary substrate. It was shown that the structure of the aluminum foils can be adjusted from dense and flat to three-dimensional by choosing an appropriate substrate rotation speed and current density. Scanning electron microscopy (SEM) and white light interferometry (WLI) were utilized to analyze the foils’ surface morphology, structure and topography. The SEM analysis of the aluminum foils showed that the rolling process produced a foil with small grains, while electrodeposition resulted in foils with different degrees of grain growth and seed formation. This was in total agreement with WLI results that revealed significant differences in terms of roughness parameters, including the peak-to-valley difference R_pv, the root-mean-square roughness R_q and the arithmetic mean roughness R_a. These were, respectively, equal to 6.8 µm, 0.35 µm and 0.279 µm for the state-of-the-art foil and up to 96.6 µm, 10.92 µm and 8.783 µm for the structured electroformed foil. Additionally, cyclic voltammetry (CV) of the aluminum foils was used to investigate their passivation behavior within the typical LIB cathode potential operation window. The strong decrease in the current density during the second cycle compared to the first cycle, where an anodic peak appeared between 4.0 and 4.4 V vs. Li/Li⁺, demonstrated that passivation occurs in the same manner as observed for commercial Al current collectors.

Tao Xu, Zuozheng Liu, Lingxu Guo et al.

Abstract Short‐term interval estimation can effectively and precisely quantify the uncertainties of renewable energy, accurately represent the range of fluctuations of uncertain variables in robust optimisation of electricity‐heating integrated energy system (EHIES) and it is getting crucial for reliable and flexible operation of renewable dominated new energy systems. The authors present a multivariate data‐driven short‐term PV power interval prediction model that consists of multiple layers, including one‐dimensional convolutional layer, ultra‐lightweight subspace attention mechanism (ULSAM), bidirectional long and short‐term memory (BiLSTM), quantile regression (QR) and kernel density estimation (KDE). The one‐dimensional convolutional layer and ULSAM can extract sequential features and highlight key information from the data; the BiLSTM processes time series data in both directions and conveys historical information; the QR and KDE models generate interval prediction with a given confidence level. Based on the proposed interval estimation, a refined PV uncertainty set can be established and adopted by robust optimal scheduling of EHIES utilising min‐max‐min algorithm. The simulation results have demonstrated the estimation accuracy and adaptability to various weather scenarios.

Manoharan Premkumar, Chandrasekaran Kumar, Thankkapan Dharma Raj et al.

Abstract The Optimal Power Flow (OPF) is a primary tool in planning and installing power systems. It attempts to minimize the operating costs associated with generating and transmitting electrical power by modifying control parameters to satisfy environmental, economic, and operational constraints. Implementing an efficient and robust optimization algorithm for the above‐said problem is critical to achieving such a typical objective. Therefore, this paper introduces and evaluates new variants of the Successive History‐based Adaptive Differential Evolutionary (SHADE) algorithm called ESHADE, SHADE‐SFS, and SHADE‐SAP to solve the OPF problems with equality and inequality constraints. Generally, the static penalty approach is widely used for eliminating infeasible solutions discovered during the search phase when searching for feasible solutions. This approach requires the accurate selection of penalty coefficients, accomplished through the trial‐and‐error method. The proposed ESHADE algorithm is formulated using Self‐Adaptive Penalty (SAP) and Superiority of Feasible Solution (SFS) mechanisms to obtain feasible solutions for OPF problems. Two IEEE bus systems are used to demonstrate the effectiveness of the proposed algorithm in handling OPF problems. The fuel cost and active power loss obtained by the proposed algorithm are better than other state‐of‐the‐art algorithms. The results reveal that the proposed framework offers significant advantages over other algorithms.

Michał Kurtyka

Po agresji Rosji na Ukrainę rozwój energetyki rozproszonej powinien nabrać przyspieszenia. To najszybszy sposób na zbudowanie nowych mocy wytwórczych, które pozwolą ograniczyć zależność Polski od importowanych węglowodorów, a także szansa na zaangażowanie kapitału prywatnego, a docelowo również na zwiększenie odporności kraju na zewnętrzne wstrząsy. Artykuł zawiera postulat osadzenia rozwoju energetyki rozproszonej na czterech fundamentach, którymi są: rozwój regulacji, modernizacja i dostosowanie infrastruktury, inwestycje w postęp technologiczny oraz edukacja i wymiana doświadczeń. Energetyka rozproszona zasługuje na przyjęcie kompleksowej strategii rozwoju (jej propozycja została opracowana w ramach projektu Gospostrateg na potrzeby Ministerstwa Klimatu i Środowiska), a także na zmianę definicji. W artykule przedstawiono propozycję, by definiować ją w odniesieniu do kryteriów mniej technicznych niż ma to miejsce obecnie, a bardziej odzwierciedlić cel istnienia, na przykład dążenie do samobilansowania.

Liang Fang, Mingzhe Chen, Kyung-Wan Nam et al.

Li-rich layered oxides utilizing reversible oxygen redox are promising cathodes for high-energy-density lithium-ion batteries. However, they exhibit different electrochemical profiles before and after oxygen redox activation. Therefore, advanced characterization techniques have been developed to explore the fundamental understanding underlying their unusual phenomenon, such as the redox evolution of these materials. In this review, we present the general redox evolution of Li-rich layered cathodes upon activation of reversible oxygen redox. Various synchrotron X-ray spectroscopy methods which can identify charge compensation by cations and anions are summarized. The case-by-case redox evolution processes of Li-rich 3d/4d/5d transition metal O3 type layered cathodes are discussed. We highlight that not only the type of transition metals but also the composition of transition metals strongly affects redox behavior. We propose further studies on the fundamental understanding of cationic and anionic redox mixing and the effect of transition metals on redox behavior to excite the full energy potential of Li-rich layered cathodes.

LIU Jun, DEND Yi, YANG Yanxi et al.

Ash plugging of the rotary air preheater widely used in large-scale power station often occurs and even reduces the efficiency of the boiler in sever cases. Therefore, a deep learning-based method was proposed for analyzing the evolution of ash accumulation for the infrared compensation images of the air preheater rotor. The sample data of the infrared compensation images of air preheater rotor was preprocessed, and the denoised image was transformed into the gray-level curve image, and the Gaussian filtering method was used for the image enhancement. Then, the gray-level co-occurrence matrix (GLCM) was established, the correlation statistics were calculated, and five different types of texture feature parameters of angular second moment (ASM) energy, contrast, entropy, inverse difference moment (IDM) and correlation were extracted. Finally, a deep belief network (DBN) model was established, which was trained with those preprocessed infrared images. The testing results show that the proposed method can not only detect effectively and monitor the ash accumulation of the air preheater rotor, but also predict the occurrence of ash blockage in advance, so as to guide the operators to optimize the operation of the ash blowing system and ensure the normal operation of the air preheater.

Nekane Nieto, Olatz Noya, Amaia Iturrondobeitia et al.

Hard carbon is one of the most promising anode materials for sodium-ion batteries. In this work, new types of biomass-derived hard carbons were obtained through pyrolysis of different kinds of agro-industrial biowaste (corncob, apple pomace, olive mill solid waste, defatted grape seed and dried grape skin). Furthermore, the influence of pretreating the biowaste samples by hydrothermal carbonization and acid hydrolysis was also studied. Except for the olive mill solid waste, discharge capacities typical of biowaste-derived hard carbons were obtained in every case (≈300 mAh·g⁻¹ at C/15). Furthermore, it seems that hydrothermal carbonization could improve the discharge capacity of biowaste samples derived from different nature at high cycling rates, which are the closest conditions to real applications.

Maureen S. Golan, Javad Mohammadi

Developing models and metrics that can address resilience against disruptions is vital to ensure power grid reliability and that adequate recovery and adaptation mechanisms are in place. In this paper, we propose a novel disruption mapping approach and apply it to the publicly available U.S. Department of Energy DOE-417 Electric Emergency and Disturbance Report to holistically analyze the origin of anomalous events and their propagation through the cyber, physical and human domains. We show that capturing the disruption process onset has implications for quantifying, mitigating, and reporting power grid resilience.

Haoran Deng, Bo Yang, Chao Ning et al.

Widespread utilization of electric vehicles (EVs) incurs more uncertainties and impacts on the scheduling of the power-transportation coupled network. This paper investigates optimal power scheduling for a power-transportation coupled network in the day-ahead energy market considering multiple uncertainties related to photovoltaic (PV) generation and the traffic demand of vehicles. The crux of this problem is to model the coupling relation between the two networks in the day-ahead scheduling stage and consider the intra-day spatial uncertainties of the source and load. Meanwhile, the flexible load with a certain adjustment margin is introduced to ensure the balance of supply and demand of power nodes and consume the renewable energy better. Furthermore, we show the interactions between the power system and EV users from a potential game-theoretic perspective, where the uncertainties are characterized by an ambiguity set. In order to ensure the individual optimality of the two networks in a unified framework in day-ahead power scheduling, a two-stage distributionally robust centralized optimization model is established to carry out the equilibrium of power-transportation coupled network. On this basis, a combination of the duality theory and the Benders decomposition is developed to solve the distributionally robust optimization (DRO) model. Simulations demonstrate that the proposed approach can obtain individual optimal and less conservative strategies.

Aydin Zaboli

Short circuit fault currents are increasing due to growing demand for electricity and high complexity in power systems. Because the fault currents reach the highest value which the breakers are unable to restrict, the electrical grid security is under jeopardy. By entering a limiting impedance into a transmission line in series, these impedances restrict the rising amounts of fault currents to levels that are acceptable. Saturated core fault current limiters (SCFCLs) are a pivotal tool for limiting fault currents rise in power networks that have good performance characteristics. In a normal condition, these limiters have slight effects on the system and can effectively limit short circuit currents when occur. In this chapter, various structures of SCFCLs with different arrangements of ac windings & dc windings are presented and the currents passing through the FCLs under the normal and faulty system conditions are assessed and compared. The flux density in various regions of the core in different arrangements has been investigated as well and the desired analyzes have been performed. Simulation will be presented based on COMSOL Multiphysics 5.4, a finite element software package which can provide a precious assessment to compare these protective devices with different configurations.

Diptish Saha, Najmeh Bazmohammadi, Jose Maurilio Raya-Armenta et al.

Several space organizations have been planning to establish a permanent, manned base on the Moon in recent years. Such an installation demands a highly reliable electrical power system (EPS) to supply life support systems and scientific equipment and operate autonomously in a fully self-sufficient manner. This paper explores various technologies available for power generation, storage, and distribution for space microgrids on the Moon. Several factors affecting the cost and mass of the space missions are introduced and analysed to provide a comprehensive comparison among the available solutions. Besides, given the effect of base location on the design of a lunar electrical power system and the mission cost, various lunar sites are introduced and discussed. Finally, the control system requirements for the reliable and autonomous operation of space microgrids on the Moon are presented. The study is complemented by discussing promising future technological solutions that could be applied upon a lunar microgrid.

Diana Böttger, Philipp Härtel

Climate and energy policy targets of the European Commission aim to make Europe the first climate-neutral continent by 2050. For low-carbon and net-neutral energy systems primarily based on variable renewable power generation, issues related to the market integration, cannibalisation of revenues, and cost recovery of wind and solar photovoltaics have become major concerns. The traditional discussion of the merit-order effect expects wholesale power prices in a system with 100 % renewable energy sources to alternate between very high and very low values. Unlike previous work, we present a structured and technology-specific analysis of the cross-sectoral demand bidding effect for the price formation in low-carbon power markets. Starting from a stylised market arrangement and by successively augmenting it with all relevant technologies, we construct and quantify the cross-sectoral demand bidding effects in future European power markets with the cross-sectoral market modelling framework SCOPE SD. As the main contribution, we explain and substantiate the market clearing effects of new market participants in detail. Hereby, we put a special focus on hybrid heat supply systems consisting of combined heat and power plant, fuel boiler, thermal storage and electrical back up and derive the opportunity costs of these systems. Furthermore, we show the effects of cross-border integration for a large-scale European net-neutral energy scenario. Finally, the detailed information on market clearing effects allows us to evaluate the resulting revenues of all major technology categories on future electricity markets.

Milan Straka, Lucia Piatriková, Peter van Bokhoven et al.

Based on the electric vehicle (EV) arrival times and the duration of EV connection to the charging station, we identify charging patterns and derive groups of charging stations with similar charging patterns applying two approaches. The ruled based approach derives the charging patterns by specifying a set of time intervals and a threshold value. In the second approach, we combine the modified l-p norm (as a matrix dissimilarity measure) with hierarchical clustering and apply them to automatically identify charging patterns and groups of charging stations associated with such patterns. A dataset collected in a large network of public charging stations is used to test both approaches. Using both methods, we derived charging patterns. The first, rule-based approach, performed well at deriving predefined patterns and the latter, hierarchical clustering, showed the capability of delivering unexpected charging patterns.