Search Results (637)

This paper presents a PSCAD-based analysis of short-circuit faults and protection characteristics in a real distribution-level microgrid that integrates a 1 MWh battery energy storage system (BESS) with a 500 kW power conversion system (PCS) and a 500 kW photovoltaic (PV) plant connected to a 22.9 kV feeder. While previous studies often rely on simplified inverter models, this paper addresses the critical gap by integrating actual manufacturer-defined control parameters and cable impedances. This allows for a precise analysis of sub-millisecond transient behaviors, which is essential for developing robust protection schemes in inverter-dominated microgrids. The PSCAD model is first verified under grid-connected steady-state operation by examining PV output, BESS power, and grid voltage at the point of common coupling. Based on the validated model, DC pole-to-pole faults at the PV and ESS DC links and a three-phase short-circuit fault at the low-voltage bus are simulated to characterize the fault current behavior of the grid, BESS and PV converters. The DC fault studies confirm that current peaks are dominated by DC-link capacitor discharge and are strongly limited by converter controls, while the AC three-phase fault is mainly supplied by the upstream grid. As an initial application of the model, an instantaneous current change rate (ICCR) algorithm is implemented as a dedicated DC-side protection function. For a pole-to-pole fault, the ICCR index exceeds the 100 A/ms threshold and issues a trip command within 0.342 ms, demonstrating the feasibility of sub-millisecond DC fault detection in converter-dominated systems. Beyond this example, the validated PSCAD model and associated data set provide a practical platform for future research on advanced DC/AC protection techniques and protection coordination schemes in real BESS–PV microgrids. Full article

Achieving high reliability remains the critical challenge for pulsed power supplies (PPS), whose core components are susceptible to severe degradation and catastrophic failure due to long-term operation under electrical, thermal and magnetic stresses, particularly those associated with high voltage and high current. This reliability challenge fundamentally limits the widespread deployment of PPSs in defense and industrial applications. This article provides a comprehensive and systematic review of the reliability challenges and recent technological progress concerning PPSs, focusing on three hierarchical levels: component, system integration, and extreme operating environments. The review investigates the underlying failure mechanisms, degradation characteristics, and structural optimization of key components, such as energy storage capacitors and power switches. Furthermore, it elaborates on advanced system-level techniques, including novel thermal management topologies, jitter control methods for multi-module synchronization, and electromagnetic interference (EMI) source suppression and coupling path optimization. The primary conclusion is that achieving long-term, high-frequency operation depends on multi-physics field modeling and robust, integrated design approaches at all three levels. In summary, this review outlines important research directions for future advancements and offers technical guidance to help speed up the development of next-generation PPS systems characterized by high power density, frequent repetition, and outstanding reliability. Full article

Microbial fuel cells (MFCs) utilizing livestock wastewater represent a critical path toward sustainable energy and net-zero emissions. To maximize this potential, this study investigates a novel circuit configuration, integrating twin MFCs with dual supercapacitors in a closed-loop system, to enhance charge storage and electricity generation. By utilizing molasses-seawater anolytes, the study establishes a performance benchmark for optimizing energy recovery in future livestock wastewater treatment applications. The self-adjusting potential difference between interconnected MFCs is verified, and supercapacitors significantly improve energy harvesting by reducing load impedance and balancing capacitor plate charges. Voltage gain across supercapacitors exceeds that of single MFC charging, demonstrating the benefits of series integration. Experimental results reveal that catholyte properties—electrical conductivity, salinity, pH, and dissolved oxygen—strongly influence MFC performance. Optimal conditions for a neutralized anolyte (pH 7.12) include dissolved oxygen levels of 5.37–5.68 mg/L and conductivity of 24.3 mS/cm. Under these conditions, supercapacitors charged with sterile diluted seawater catholyte store up to 40% more energy than individual MFCs, attributed to increased output current. While the charge balance mechanism of supercapacitors contributes to storage efficiency, its impact is less pronounced than that of conductivity and oxygen solubility. The interplay between electrochemical activation and charge balancing enhances overall electricity harvesting. These findings provide valuable insights into optimizing MFC-supercapacitor systems for renewable energy applications, particularly in livestock wastewater treatment. Full article

The study presents an upgraded design and the results of experimental investigations of a solid-propellant pulsed plasma thruster (PPT) in which graphite simultaneously serves as both the propellant and the ignition element. The proposed configuration comprises a planar parallel system of copper electrodes and a graphite initiating electrode equipped with an electromagnetic discharge-triggering mechanism. Experimental tests were conducted under vacuum conditions of approximately 10⁻⁵ Torr at an energy-storage capacitor voltage of 800–1400 V. Discharge current amplitudes of up to 3.16 kA were recorded at a single-pulse energy of up to 4.41 J. The measured impulse bit was about 17.1 μN $·$s, and the plasma jet exhaust velocity reached 11.1 km/s. Spectroscopic analysis of the plasma confirmed the presence of characteristic carbon emission lines, thereby indicating the active participation of the graphite propellant in the formation of the plasma plume. The present work continues previous research on PPTs with graphite electrodes and is aimed at further miniaturization of the earlier developed design. The primary objective of the study is the experimental validation of the proposed discharge concept in a planar parallel electrode configuration while preserving the key thrust and energy performance characteristics of the thruster. Full article

In this present study, sodium- and strontium-modified bismuth titanate—Bi_0.5Na_0.5TiO₃ (BNT) and Bi_0.5Sr_0.5TiO₃ (BST)—were synthesized using the auto-combustion technique with citric acid (C₆H₈O₇) and glycine (C₂H₅NO₂) as fuels in an optimized ratio of 1.5:1. The resulting powders were characterized using X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, UV–Visible diffuse reflectance spectroscopy (DRS), and Fourier-transform infrared (FT-IR) spectroscopy. The electrical behavior of the samples was studied using an LCR meter. XRD analysis confirmed the formation of a single-phase perovskite structure with average crystallite sizes of 18.60 nm for BNT and 22.03 nm for BST, attributed to the difference in ionic radii between Na⁺ and Sr²⁺. An increase in crystallite size was accompanied by a corresponding increase in lattice parameters and unit-cell volume. The Williamson–Hall analysis further validated the strain-size contributions. EDX (Energy-Dispersive X-ray analysis) results confirmed successful incorporation of Na⁺ and Sr²⁺ without detectable impurity phases. Optical studies revealed distinct absorption peaks at 341 nm for BNT and 374 nm for BST, and the optical bandgap (E_g), calculated using Tauc’s relation, was found to be 2.6 eV and 2.0 eV, respectively. FT-IR spectra exhibited characteristic Ti-O vibrational bands in the range of 420–720 cm⁻¹, consistent with the perovskite structure. For electrical characterization, the powders were pelletized under 3-ton pressure and sintered at 1000 °C for 3 h. The dielectric constant (ε_r), dielectric loss (tan δ), and ac conductivity (σ) of both samples increased with frequency. The combined structural, optical, and electrical results indicate that the optimized compositions of BNT and BST possess properties suitable for use in capacitors and other energy-storage applications. Full article

This study systematically investigates the influence of capacitor energy storage parameters on the energy utilization efficiency of the underwater electrochemical explosion process. By integrating spherical and cylindrical shock wave propagation models, the pulse shock wave energy under different capacitor energy storage levels was theoretically calculated and experimentally validated. The results indicate that the applicability of the shock wave propagation model depends on the distance and aquatic environment: the spherical model is more suitable for short-distance, deep-water conditions, whereas the cylindrical model performs better for long-distance or shallow-water conditions. Within the energy storage range of up to 100 J, increasing the capacitance significantly enhances both the pulse energy output and energy utilization efficiency. Specifically, as the stored energy increased from 13 J to 100 J, the shock wave energy rose from 0.051 J to 2.45 J, and the energy utilization rate improved from 0.39% to 2.45%. Nevertheless, the overall energy utilization efficiency remains below 10%. This study confirms that rationally configuring capacitor parameters can effectively regulate the discharge process, providing important experimental and theoretical support for optimizing energy utilization efficiency. Full article

This paper reviews the research progress of supercapacitors (SCs), including the influence of electrode materials on energy storage mechanism and performance, and life prediction. Supercapacitors show application potential in many fields due to their high-power density, fast charge–discharge capability, long cycle life, and environmental protection characteristics. In this paper, the energy storage mechanism of the double-layer capacitor, pseudocapacitor, and asymmetric supercapacitor are discussed. New electrode materials, such as carbon-based materials, metal oxides, and conductive polymers, are reviewed based on the performance optimization measures that are involved in the microstructure design of electrode materials, and integrate the rule prediction of supercapacitors into comprehensive learning. When designing and using supercapacitors, we should not only pay attention to their life but also pay attention to their remaining service life in real time. The paper also mentions the progress of life prediction technology, which is of great significance to improve the reliability and maintenance efficiency of energy storage equipment, and ensure the long-term stable operation of energy storage systems. Future research directions include increasing energy density, extending life, adapting to extreme environments, developing flexible and wearable devices, intelligent management, and reducing costs. Full article

This paper introduces a novel control archetype designed to mitigate high-altitude electromagnetic pulse (HEMP) $E_3$ disturbances on the power grid, as well as information on performance and specifications of different control laws for the controller archetype. This method of protection has been overlooked in the literature until now. A controlled voltage supply is placed on the load-side of a transformer, diverting unwanted power from the transformer core to prevent saturation. The controlled voltage source is modeled using four control laws: an integral controller (capacitor), Linear Quadratic Regulator (LQR), an energy storage minimized feedforward control law, and a Hamiltonian feedback law. Results show that the Hamiltonian feedback law and the energy storage minimization feedforward control law both flat-line magnetic flux with similar actuator requirements. The LQR approach requires less energy storage than the other two laws, depending on control tuning, as it allows greater exogenous current flow through the neutral path to ground. This leads to further optimization opportunities based on acceptable exogenous current levels. A sweep of different LQR gains revealed a reduction of approximately $32\%$ in minimum control effort, $47\%$ in minimum power to maintain saturation bounds, $20\%$ in energy storage requirements, and $59\%$ in required controller bandwidth. Voltage and bandwidth requirements of the load-side controller are comparable to neutral blocking requirements with energy and power requirements being higher for the load-side controller. This, however, comes with the benefit of being able to use pre-existing assets—neutral blocking devices have not been deployed. Additionally, the load-side blocking capacitor degrades transformer performance compared to the unmitigated system. Full article

The results of practical considerations on the issue of conditioning and storing energy obtained from generally available electromagnetic field sources (e.g., commonly used telecommunication systems and RFID radio frequency identification systems) or other potential areas of energy harvesting have been presented in this paper. Due to the low efficiency of this type of alternative power source for electronic microsystems, it is necessary to properly process the obtained energy in order to achieve parameters suitable for powering subsequent elements of the powered system (supply voltage, internal resistance of the source, limitations resulting from the permissible parameters of the components used, etc.) and its effective storage. This paper analyses the use of increasingly available and technologically advanced supercapacitors as the main energy storage device. These are electronic components that fill the gap between commonly known and widely used capacitors and more complex and expensive battery systems that require complicated systems to support the charging and discharging of such storage devices. However, they require consideration of their dynamic characteristics in terms of the charging and energy storage process. The properties of such components were investigated, the requirements and application limitations as a battery were determined, and the results of tests of selected supercapacitors were analysed. Based on the obtained data, several concepts for energy conditioning systems were presented, enabling the practical use of the advantages of supercapacitors as the main energy storage device, for example, an electromagnetic field energy harvester system from an RFID system. Full article

The escalating demand for high-performance energy storage devices has driven extensive research into flexible electrode materials for supercapacitors. Integrating structured carbon nanomaterials with flexible substrates to construct binder-free electrode architectures represents a promising strategy for improving supercapacitor capacitance and rate capability. However, achieving stable, binder-free integration of structure-controlled nanostructured carbon materials with flexible substrates remains a critical challenge. In this study, we report a direct synthesis approach for one-dimensional (1D) carbon nanofibers (CNFs) on commercial flexible carbon fabric (CF) via chemical vapor deposition (CVD). The resulting CNFs exhibit two typical average diameters—approximately 25 nm and 50 nm—depending on the growth temperature, with both displaying highly graphitized structures. Electrochemical characterization of the CNFs/CF composites in 1 M H₂SO₄ electrolyte revealed typical electric double-layer capacitor (EDLC) behavior. Notably, the 25 nm-CNFs/CF electrode achieves a high specific capacitance of 87.5 F/g, significantly outperforming the 50 nm-CNFs/CF electrode, which reaches 50.2 F/g. Compared with previously reported carbon nanotube CNTs/CF electrodes, the 25 nm-CNFs/CF electrode exhibits superior capacitance and lower resistance. Full article

This paper proposes a single-phase AC-AC solid-state transformer (SST) that eliminates bulky energy storage components. The proposed matrix-type structure comprises a line-frequency (LF) rectifier, a half-bridge (HB) LLC resonant converter, a buck–boost converter, and an LF inverter. The HB LLC resonant converter not only achieves high efficiency at unity voltage gain but also provides high-frequency (HF) isolation as a DC transformer (DCX). Meanwhile, the buck–boost converter ensures precise voltage regulation. The replacement of traditional DC-link electrolytic capacitors with small film capacitors effectively suppresses the second-harmonic power ripple, leading to a significant improvement in both power density and operational reliability. Experimental results from a 1 kW prototype demonstrate high-quality sinusoidal input and output, a wide range of zero-voltage switching (ZVS) operations, and stable output voltage control. Full article

Active-control coils on Keda Torus eXperiment (KTX) are used to suppress error fields and mitigate MHD instabilities, thereby extending discharge duration and improving plasma confinement quality. Achieving effective active MHD control imposes stringent requirements on the coil power supplies: wide-bandwidth and high-precision current regulation, deterministic low-latency response, and tightly synchronized operation across 136 independently driven coils. Specifically, the supplies must deliver up to ±200 A with fast slew rates and bandwidths up to several kilohertz, while ensuring sub-100 μs control latency, programmable waveforms, and inter-channel synchronization for real-time feedback. These demands make the power supply architecture a key enabling technology and motivate this work. This paper presents the design and simulation of the KTX active-control coil power supply. The system adopts a modular AC–DC–AC topology with energy storage: grid-fed rectifiers charge DC-link capacitor banks, each H-bridge IGBT converter (20 kHz) independently drives one coil, and an EMC filter shapes the output current. Matlab/Simulink R2025b simulations under DC, sinusoidal, and arbitrary current references demonstrate rapid tracking up to the target bandwidth with ±0.5 A ripple at 200 A and limited DC-link voltage droop (≤10%) from an 800 V, 50 mF storage bank. The results verify the feasibility of the proposed scheme and provide a solid basis for real-time multi-coil active MHD control on KTX while reducing instantaneous grid loading through energy storage. Full article

A novel strategy was adopted to enhance the energy storage properties of materials through constructing a vacancy defect. BaTi_1−xCu_xO_3−x (abbreviated as BTCx, x = 0–0.05) ceramics were prepared. The influences of Cu doping on structure and electrical properties were systematically investigated in this study. The result reveals that the oxygen vacancies in BTCx ceramics can inhibit grain growth and improve breakdown strength. Notably, as Cu content increases, the abundance of oxygen vacancies of the BTCx ceramics intensifies the relaxor behavior and induces double hysteresis loops with high energy storage performance. The excellent energy storage density of 1.34 J/cm³ and efficiency of 90.1% were achieved for BTC3 ceramics at 180 kV/cm, which indicates that the outstanding energy storage properties of BTCx ceramics make them have broad application prospects in advanced pulse power capacitors. Full article

This paper proposes a coordinated hybrid VAR compensation strategy that leverages the dynamic support capabilities of a grid-forming (GFM) battery energy storage system (BESS) and solar photovoltaic (PV) plant to enhance the stability of inverter-dominated power systems. The hybrid compensator integrates a VSC-based static synchronous compensator (STATCOM) with a thyristor-switched capacitor (TSC), combining the fast dynamic response of the STATCOM with the high reactive power capacity of the TSC. A coordinated control framework is developed to enable seamless interaction between the hybrid VAR compensator and the GFM-controlled PV and BESS units, ensuring improved voltage regulation and transient stability under varying operating conditions. The PV plant operates at maximum power Point while maintaining its grid-forming capability, thereby maximizing renewable energy utilization while contributing to frequency and voltage support. The effectiveness of the proposed strategy is validated through FPGA-based real-time simulations under scenarios including large load variations, solar irradiance fluctuations, and grid disturbances. Results show that the coordinated operation enhances voltage stability, strengthens reactive power support, mitigates low-frequency oscillations, and significantly improves the dynamic performance of low-inertia, inverter-dominated grids. Full article

Leakage current is a prevalent issue in non-isolated photovoltaic (PV) energy storage inverter systems, which not only induces additional power losses but also poses potential safety hazards and degrades system operational efficiency. To address this critical problem, this paper proposes an improved three-phase four-leg PV energy storage inverter topology integrated with independent split capacitors, based on the traditional three-level topology. First, an in-depth analysis of the leakage current generation mechanism is conducted, focusing on the impacts of common-mode voltage fluctuations and parasitic capacitance on leakage current paths. By establishing an equivalent mathematical model, a systematic comparative analysis is performed between the proposed topology and the traditional topology regarding key performance indicators, including leakage current suppression capability, DC-side neutral point potential stability, and power quality. Notably, the improved topology requires no additional control strategy design; under the same carrier modulation strategy and parameter configuration as the traditional topology, it can stably constrain the DC-side neutral point potential to fluctuate within an acceptable range. Experimental results demonstrate that the proposed topology reduces the peak leakage current to within 200 mA while maintaining the total harmonic distortion (THD) of the load-side current at a low level. These performance metrics comply with the relevant national and industry power quality standards for PV grid-connected systems, endowing the topology with high engineering practical value. Full article