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High voltage power capacitors employ the oil-impregnated polypropylene film as the insulation. The swelling phenomenon might drive the antioxidants and small molecules within the film to migrate into the oil. It is necessary to comprehensively investigate the physical migration mechanism of antioxidants and their impact on the electrical performance of the oil-film combination insulation system and, consequently, formulate the proper selective prescription of antioxidants. Theoretical elucidation of the competitive interaction mechanism between the film and the oil in attracting antioxidant molecules was achieved through the calculation of inter-molecular binding energy, and the migration coefficient ηm was introduced to quantify the migration characteristics of antioxidants. Experimentally, the effects of antioxidants on the space charge distribution of the film, the dielectric properties of the oil, and the breakdown characteristics of both the film and oil were investigated. The experimental conclusions are consistent with theoretical analysis. The lamellar structure antioxidant molecules with ηm > 1 tend to migrate from the film to the oil, which results in increased dielectric loss and decreased breakdown strength of the insulating oil. In addition, the presence of phosphorus atoms in phosphite antioxidants contributes to a reduction in the breakdown strength of the film. For capacitor grade polypropylene film, in addition to the synergistic effect between different types of antioxidants on the thermo-oxidative stability, the structure of the antioxidant molecules and its influence on the electrical performance of the oil–film systems should also be taken into account. [ABSTRACT FROM AUTHOR]

A new principle for constructing small-sized capacitor DC-DC regulators that provide energy-efficient conversion and multi-zone energy regulation of hydrogen fuel cells is proposed. It consists in converting the energy of their current into the energy of a constant voltage source with further alternating changes in its low-voltage regulation subranges. It is carried out by discretely changing the number of resonant chains of a step-up capacitor DC-DC converter in combination with a smooth change in the charge level of its first chain using a low-power classic PWM constant voltage regulator. Improving the energy properties of the regulator is achieved by multi-zone regulation and soft switching of transistors in the power circuit of the capacitor DC-DC converter. The energy properties of the proposed regulator have been studied. It is shown that with an increase in the number of resonant chains in the capacitor DC-DC converter, there is a tendency for the controller efficiency to increase. For the various regulator circuits considered in the work, the regulating characteristics were obtained and a comparative assessment of their efficiency was carried out. A comparative analysis of energy and design properties proves the significant advantage of a circuit using a Boost PWM constant voltage regulator. [ABSTRACT FROM AUTHOR]

ABSTRACT DC–AC inverters are an important set of power converters when it comes to integration of the renewable energy resources in to the AC grid or to local AC loads. The multilevel inverters (MLIs) are a common and popular choice for such applications. However, MLIs require many switching devices for higher number of voltage levels, multiple isolated DC sources, need for additional charge‐balancing circuits for the DC‐link capacitor, and unequal voltage stress in the devices at higher power levels. Switched capacitor–based inverters are emerging as a popular alternative to the conventional MLIs that do provide inherent charge balancing, reduced device stress, output voltage–boosting capability, and highly compact converters. This work proposes such a current‐fed DC–AC switched capacitor converter (SCC). This converter offers advantages such as reduced count of switched capacitors and power devices, elimination of load‐side filtering elements, reduced switching ripple in output voltage due to inherent interleaving, reduced voltage and current total harmonic distortion (THD), and lower ratings of the switched capacitors. An adaptive hysteresis control scheme is used to track the voltage across the switched capacitors to a desired sinusoidal reference. The overall control architecture is straightforward to implement, and the switching architecture uses overlapping logic to prevent interrupting the input current. The work includes a complete analysis and design procedure. A 500‐W laboratory prototype of the proposed converter is built, with the control architecture implemented using the TMS320F28379D microcontroller. Simulation results are verified with experimental outcomes. [ABSTRACT FROM AUTHOR]

Antiferroelectric (AFE) materials are potentially useful for energy storage applications. Lead hafnate (PbHfO 3) is one of the prototypical AFE materials. However, its critical field (E cr) which is needed to induce the AFE to ferroelectric phase transition is close to the dielectric breakdown strength. To reduce E cr , we prepare the solid solutions of (1- x)PbHfO 3 – x BiAlO 3 (x = 0.00–0.04) via solid state synthesis. The crystal structures, dielectric behaviour, ferroelectric properties, and energy storage properties are investigated. A temperature-composition phase diagram is established. At room temperature, the crystal symmetry of all compositions is orthorhombic with the Pbam space group. Upon heating, the transition to the AFE orthorhombic Imma phase is observed at the temperature T C1 , which slightly decreases with increasing x , followed by the transition to the cubic phase at the temperature T C2 , which does not depend on x. Distinct dielectric anomalies are observed at T C1 and T C2. It is found that BiAlO 3 substitution reduces E cr and the polarization–electric field relations display characteristic double hysteresis loops. For x = 0.04, at a comparatively small applied field of 130 kV/cm, the values of recoverable energy density (W rec) and efficiency of 0.24 J/cm3 and 84 %, respectively, are obtained. At 190 °C, a W rec = 0.75 J/cm3 and a very high efficiency of 92 % are obtained at the field of 50 kV/cm. Thus, the prepared material can potentially be used in high-temperature pulsed power capacitors for energy storage applications within the temperature range from room temperature up to 190 °C. [ABSTRACT FROM AUTHOR]

Energy storage in electrochemical hybrid capacitors involves fast faradaic reactions such as an intercalation, or redox process occurring at a solid electrode surface at an appropriate potential. Hybrid sodium‐ion electrochemical capacitors bring the advantages of both the high specific power of capacitors and the high specific energy of batteries, where activated carbon serves as a critical electrode material. The charge storage in activated carbon arises from an adsorption process rather than a redox reaction and is an electrical double‐layer capacitor. Advanced carbon materials with interconnecting porous structures possessing high surface area and high conductivity are the prerequisites 1128to qualify for efficient energy storage. Herein, we have demonstrated that a porous honeycomb structure activated carbon derived from Australian hemp hurd (Cannabis sativa L.) in aqueous Na2SO4 electrolyte showed a specific capacitance of 240 F/g at 1 A/g. The mass ratio of biochar to KOH during the chemical activation associated with the synthesis temperature influences the change in morphologies, and distribution of pore sizes on the adsorption of ions. At higher synthesis temperatures, the tubular form of the honeycomb starts to disintegrate. The hybrid sodium‐ion device employing hemp‐derived activated carbon (HAC) coupled with electrolytic manganese dioxide (EMD) in an aqueous Na2SO4 electrolyte showed a specific capacitance of 95 F/g at 1 A/g having a capacitance retention of 90 %. The hybrid device (HAC||EMD) can possess excellent electrochemical performance metrics, having a high energy density of 38 Wh/kg at a power density of 761 W/kg. Overall, this study provides insights into the influence of the activation temperature and the KOH impregnation ratio on morphology, porosity distribution, and the activated carbon's electrochemical properties with faster kinetics. The high cell voltage for the device is devoted to the EMD electrode. [ABSTRACT FROM AUTHOR]

A frequency up-conversion piezoelectric–electromagnetic hybrid wave energy harvester (FHWEH) based on magnetic coupling has been proposed. The wave motion is converted into rotation of the rotor by means of a rack and pinion. The excitation frequency can be increased by multiple rotating magnets to approach the cantilever beam intrinsic frequency. The piezoelectric and electromagnetic hybrid mechanism improves the output performance of the FHWEH. The main factors affecting the prototype output have been identified through theoretical modeling and magnetic simulation analysis. The laws governing the influence of magnet spacing, magnet size and magnet quantity on the output performance were investigated experimentally. Under optimal conditions, the maximum voltage of the piezoelectric and electromagnetic parts of the FHWEH were 43.87 V and 1.83 V, respectively, and the maximum power was 20.31 mW and 0.32 mW. The output of the prototype was processed by a rectifier circuit to charge capacitors and power light-emitting diodes (LEDs). The device has been validated for powering miniature sensors and its feasibility in sensor monitoring systems. It provides a new idea and a feasible method for self-powering sensor monitoring systems. [ABSTRACT FROM AUTHOR]

Voltage notches are steady-state sub-cycle waveform distortions caused by the normal operation of line-commutated power converters, significantly impacting power quality in industrial low-voltage (LV) networks. Despite their common occurrence, research on this phenomenon is still incipient, and realistic simulation platforms are lacking. This paper introduces a detailed MATLAB (R2024a)/Simulink-based simulation platform that models a benchmark low-voltage industrial installation, including a six-pulse controlled rectifier, linear loads, and a capacitor bank for power factor correction. Systematic simulations are performed with the platform to examine the sensitivity of notch characteristics to key parameters within plausible ranges, such as short-circuit power at the point of common coupling, commutation reactance, firing angle, snubber circuits, and rated power of the rectifier. In addition, parameters such as the rated power of linear loads and the compensation power of the capacitor bank are examined. Other influencing parameters including background voltage unbalance and distortion are also modeled and considered. A comparative analysis with field measurements from German industrial LV networks validates the plausibility and suitability of the simulations. Building upon this platform, a Monte Carlo simulation approach is adopted to generate extensive datasets of realistic voltage notch waveforms by randomly varying these key parameters. A case study conducted under conditions typical of German LV networks demonstrates the applicability of the simulations. To support further research, the simulation platform and exemplary synthetic waveforms are provided alongside the paper, serving as a valuable tool for testing and designing strategies for analysis, detection, and monitoring of voltage notches. [ABSTRACT FROM AUTHOR]

This work consists of the analysis and design of a LC series resonant inverter with reactive element control for induction heating hardening applications. This novel method uses a current-controlled variable transformer (VT) to control the reflected inductance of the inductor in the resonant, and a magnetic energy recovery switch (MERS) to vary the influence of the capacitor as a reactive power compensation element. This converter topology allows quality factor (Q) or operating frequency (f s w) to be adjusted, making it possible to harden workpieces of different geometries and materials with a single converter. In the article, the design of both elements will be studied and tested. Experimental results were carried out with a 10 kW induction heating inverter prototype, with a frequency range of 60 kHz to 100 kHz and a quality factor of 6 to 10, measuring efficiencies above 95%. [ABSTRACT FROM AUTHOR]

NaNbO 3 (NN)-based lead-free dielectric ceramics exhibit great energy storage density and environmental friendliness, making them attractive options for use in pulse power capacitors. Herein, novel NN-based ceramics, namely, 0.7Na 1-3 x Sm x NbO 3 -0.3(Sr 0.7 Bi 0.2)(Ti 0.8 Zr 0.2)O 3 , were designed via composition modification in order to improve recyclable energy storage density (W rec), dielectric breakdown strength (E b), and charge-discharge rate. The phase composition, microstructure, dielectric performances and energy storage performances of the resultant ceramics were methodically studied. Ultimately, a large E b of 380 kV/cm and a great W rec of 3.2 J/cm3 were attained by the NN-SBTZ-0.01Sm ceramic. In addition, NN-SBTZ-0.01Sm ceramic exhibited outstanding temperature and frequency stabilities, which facilitated the application of dielectric capacitors. Meanwhile, high current density (C D = 268 A/cm2), and ultrafast discharge rate (t 0.9 = 35 ns) made NN-SBTZ-0.01Sm ceramic have potential applications in pulse power systems. [ABSTRACT FROM AUTHOR]

Introduction: Super capacitors were regarded as one of the most effective frequency regulation technologies in power systems. The major issue of applying super capacitors for frequency regulation is the limited energy capacity and the high construction costs. The pumped storage units have been developed and applied in power systems for decades, whereas it was rarely operated to regulate the system frequency due to the operation limitations. The pumped storage units could be operated as a hydro generator under the generation mode and provide effective frequency regulation service with the conventional automatic generation control (AGC) system while its output power was constant under the pumping mode. Method: In this paper, the pumped storage unit was controlled to participate in frequency regulation under the generation mode with super capacitors. Considering the AGC system could not consider the state of charging (SOC) of super capacitors for frequency regulation, an optimization model was proposed to determine the operation points for super capacitors and pumped storage units under a model predictive control (MPC) strategy to regulate the system frequency for power systems. Results and Discussion: Based on the various operation scenarios, the effectiveness and costs of pumped storage units and super capacitors to provide frequency regulation services were discussed. It was indicated that pumped storage units and super capacitors were effective technologies for power systems. [ABSTRACT FROM AUTHOR]

This paper investigates and technically demonstrates a capacitive power transfer (CPT) system applicable to the charging of emerging very‐low‐power portable devices. The constant‐current operation of the primary LCL compensation in CPT is implemented and analysed to simplify the system design process and minimize the configuration on the receiving side. Additionally, the system design considerations for the capacitive coupler and the diode rectifier are presented based on the battery charging specifications. All the design concepts and considerations are validated through experimentation with a 13.56 MHz CPT system, which achieves load‐independent constant‐current output from full‐load to light‐load (one‐tenth of the full load) charging operations. [ABSTRACT FROM AUTHOR]

Characterized by its exceptional electrical, physical, and chemical properties, 1-phenyl-1-xylylethane (PXE) insulating oil finds extensive application in the realm of power capacitor insulation. In this study, molecular simulation is employed to investigate the reactivity of PXE insulating oil molecules and the impact of temperature on water diffusion behavior in PXE insulating oil, as well as its solubility. The findings demonstrate a higher propensity for hydrogen atoms in nucleophilic and electrophilic positions within PXE insulating oil molecules to interact with water molecules. The inclusion of a temperature field enhances the Brownian motion of water molecules and improves their diffusion ability within the oil. Furthermore, the temperature field diminishes the interaction force between water molecules and the oil medium. Under the influence of this temperature field, there is an increase in the free volume fraction of PXE insulating oil, leading to a weakening effect on hydrogen bonds between oxygen and hydrogen atoms within PXE insulating oil. Additionally, with increasing temperature, there is an elevation in moisture solubility within insulating oil, resulting in a transition from a suspended state to a dissolved state. [ABSTRACT FROM AUTHOR]

Conventional multi-level inverters such as neutral point clamped and flying capacitor inverters do not have boosting capability and self-balanced capacitor voltage. Thus, in this paper, we propose a novel three-level inverter based on switched capacitors to solve the above problems. The proposed inverter has lower voltage stress than the general switched-capacitor multi-level inverter. Meanwhile, an improved modulation strategy is adopted in the proposed inverter. The three-level space vector diagram is converted into a two-level one, and the space vector modulation is simplified. Then, we analyze the power loss and design guidelines for the device in the inverter. Finally, a corresponding simulation and an experimental platform will be established to verify the feasibility of the proposed inverter. The results prove that the proposed three-level inverter has good performance and dynamic response that meets the requirements. [ABSTRACT FROM AUTHOR]

This work presents an LC filter design methodology that considers the optimization of the converter as a whole: filter, semiconductor switches, and DC bus. The optimization is made in light of the system losses, volume, and the capacitors lifetime, discussing the advantages and disadvantages of decisions in the parametric design of the filter (of the values of L and C). The technology of components and construction challenges are considered in the design. The manuscript guides the design process of the filter in two steps: first, by providing the means to perform the parametric sweep of possible filter designs, according to the converter specifications and other restrictions; second, by describing how the hardware design is carried out and indicating the models and methods that are being used. Individualized analyses for each part of the converter system are made, and using the proposed methodology, three design examples are provided and analyzed, each choosing the filter parameters with different objectives: minimum volume, maximum capacitor lifetime, or maximum efficiency. Results show that using Kool M μ material results in the lowest filter volumes and losses. It is also shown that for the DC bus design, there is a compromise between volume and lifetime, with a greater number of capacitors increasing both attributes. By designing the system using the proposed methodology, the minimum volume is achieved at an operating point that differs from the individual minimum volumes of the filter and the inverter, and the lifetime is only 1.78% than the maximum lifetime point. [ABSTRACT FROM AUTHOR]

Single-phase lines are typically used to distribute electricity economically to remote or rural locations. This system can handle three-phase loads in addition to single-phase loads. However, these distribution lines are vulnerable to issues with declining power quality on both the single-phase source and the three-phase load due to their length and inherent environmental faults. The goal of the project is to use the Sugeno Fuzzy Inference System (FIS) method to enhance the power quality performance of a single-phase-to-three-phase (1Ph-3Ph) unified power quality conditioner (UPQC) supplied by a photovoltaic (PV) array. The 1Ph-3Ph-UPQC-PV system is powered by a PV array that is connected to the system without needing a DC-link capacitor circuit. To maintain a steady voltage connected to the DC-link 1Ph-3Ph-UPQC series and provide active power to the load during disturbances, the PV array serves as a replacement for the DC-link capacitor. When figuring out the ideal parameters for proportional and integral (PI) constants, the Sugeno-FIS approach is utilized to get beyond the drawbacks of PI. A single linear load (L) and a single non-linear load (NL) are linked to each of the three system configurations (1Ph-3Ph-UPQC-PV) with 6 interference modes. Each combination of 1Ph-3Ph-UPQC-PV, using the Sugeno FIS Method, is compared with PI, resulting in a total of 12 modes of interference. In the 1Ph-3Ph-UPQC-PV with Modes 1-6, Sugeno FIS control is capable of producing three-phase load voltage THD and single-phase source current THD, which are lower than PI control and both comply with IEEE Standard 519. Modes 1-6, using PI, are able to generate a load voltage THD in the range of 1.14% to 5.19%. Otherwise, with the Sugeno-FIS, modes 1-6 are able to reduce the load voltage THD to between 1.11% and 3.70%. Modes 1-6 are capable of producing the source current THD between 0.50% and 2.40%. Otherwise, using the Sugeno-FIS, modes 1-6 are able to reduce the source current THD between 0.08% and 1.08%. The Sugeno FIS control in the system 1Ph-3Ph-UPQC-PV is able to improve the source power factor better than the PI control in all fault modes. Modes 1-6 with PI are able to maintain a source power factor between 0.99971 and 0.99999. Otherwise, using Sugeno FIS, modes 1-6 are able to improve the source power factor between 0.9999 and 1.0. The 1Ph-3Ph-UPQC-PV system using the PI/Sugeno FIS method connected to a non-linear load containing high distortion in Modes 4-6 is able to reduce the source current THD significantly. Mode 6 using FIS Sugeno is able to reduce the load current THD on phase A to source current THD of 882.05% into 0.09%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we present a high power-added efficiency (PAE) and high gain per stage 60 GHz power amplifier (PA). The proposed PA consists of a two-stage common-source amplifier that incorporates neutralization capacitors and compensation inductors to enhance both gain and efficiency. The gain characteristics are analyzed, demonstrating that the proposed design improves both gain and efficiency. Implemented in 65 nm CMOS technology, the PA achieves a saturated output power of 13.4 dBm at 60 GHz, with a maximum PAE of 26.7% from a 1 V supply. The output 1 dB compression point is 10.5 dBm, with a PAE of 16%. The PA occupies a core chip area of 0.094 mm2. [ABSTRACT FROM AUTHOR]

Abstract With a large number of film capacitors being deployed in critical locations in electrical and electronic systems, artificial intelligence (AI) technology is also expected to address the problems encountered in this process. According to our findings, AI applications can cover the entire lifecycle of film capacitors. However, the AI safety hazards in these applications have not received the attention they deserve. To meet this, the authors argue, with specific examples, risks that flawed, erratic, and unethical AI can introduce in the design, operation, and evaluation of film capacitors. Human‐AI common impact and more multi‐dimensional evaluation for AI are proposed to better cope with unknown, ambiguity, and known risks brought from AI in film capacitors now and in the future.

This research introduces a novel damped alternating current (DAC) testing methodology, which integrates an enhanced DAC generator with a pulse‐based distributed partial discharge (PD) detection technique. The advanced DAC generator is designed without the need for high voltage (HV) solid‐state switches, thereby offering a cost‐effective solution for field‐testing voltage generation through a direct current–alternating current conversion approach. To meet the demand for high instantaneous power, a capacitor bank is employed as the power supply. Furthermore, the implementation of a distributed PD detection technique enhances sensitivity and eliminates limitations associated with cable length. To minimize the construction costs of the distributed PD‐detection system, a pulse synchronization technique has been employed. Efforts to reduce the system's weight were informed by simulations, resulting in the design and development of a prototype weighing 850 kg for a 64/110 kV power cable. The reduction in the number of HV solid‐state switches contributes to significant cost savings, amounting to tens of thousands of dollars, when compared to conventional DAC generators. Laboratory and field tests validated the effectiveness of the cost‐efficient DAC testing methodology. [ABSTRACT FROM AUTHOR]

Dielectric capacitors with excellent power density and rapid charge-discharge rates have received significant attention in the field of pulsed power. In this study, anti-ferroelectric NaNb 0.98 Ta 0.02 O 3 was doped into (Na 0.5 Bi 0.5) 0.935 Sr 0.065 TiO 3 ceramics, resulting in a substantial improvement of the integrated energy storage performance of the ceramics. Multiscale testing confirmed that the ceramic system formed a dense solid solution with a single-phase perovskite structure. Increasing the content of NaNb 0.98 Ta 0.02 O 3 effectively enhances the relaxation and energy storage properties of the ceramics, while reducing average grain size improves their breakdown field strength, leading to excellent electrical properties at 30 kV/mm field strength when x = 0.2 for this ceramic system - exhibiting recoverable energy storage density W rec = 7.98 J/cm3 and energy storage efficiency η = 90 %. Furthermore, it demonstrates excellent stability over a wide frequency range (5–90 Hz): W rec = 7.97 ± 2 % J/cm3, η = 89 ± 1 %; as well as stability over a wide temperature range (30–200 °C): W rec = 7 ± 2 % J/cm3, η = 89 ± 1 %, along with a rapid charging-discharging rate t 0.9 = 0.32 μs. These outstanding properties indicate great prospects for future applications of this ceramic system in the field of energy storage capacitors. [ABSTRACT FROM AUTHOR]

Proton batteries have emerged as a promising solution for grid‐scale energy storage benefiting their high safety and abundant raw materials. The battery chemistry based on proton‐ions is intrinsically advantageous in integrating fast diffusion kinetics and high capacities, thus offering great potential to break through the energy limit of capacitors and the power limit of traditional batteries. Significant efforts have been dedicated to advancing proton batteries, leading to successive milestones in recent years. Herein, the recent progress of proton batteries is summarized and insights into the challenges in electrodes, electrolytes and future opportunities for enhancing full‐cell applications are provided. The fundamentals of electrochemical proton storage and representative faradaic electrodes are discussed, delving into their current limitations in mechanism studies and electrochemical performances. Subsequently, the classification, challenges, and strategies for improving protonic electrolytes are addressed. Finally, the state‐of‐the‐art proton full‐cells are explored, and views on the rational design of proton battery devices for achieving high‐performance aqueous energy storage are offered. [ABSTRACT FROM AUTHOR]

Lithium-ion capacitors (LICs) possess the potential to satisfy the demands of both high power and energy density for energy storage devices. In this report, a novel LIC has been designed featuring with the MnOx/C batterytype anode and activated carbon (AC) capacitortype cathode. The Nano-spheroidal MnOx/C is synthesized using facile one-step combustion method. Benefiting from the uniform distribution of the MnOx/C nano-spheroidal particle, a fast kinetics for both charge-transfer and ion-diffusion process is realized, promoting battery-like and capacitive energy storage. As anticipated, the MnOx/C composite material exhibits an exceptional capacity of 1167.2 and 828.5 mAh g− 1 from the first and the 100th cycle at 0.1 A g− 1, high rate capability of 171.1 mAh g− 1 even at a high rate of 2 A g− 1, much higher than pure MnOx. The MnOx/C//AC LIC displays an excellent electrochemical performance with excellent energy density of 66.9 Wh kg− 1 (250 W kg− 1) and remarkable power density of 2500 W kg− 1 (11.7 Wh kg− 1). These encouraging results make the electrode material and electrode system promising for nextgeneration highperformance energy storage devices. [ABSTRACT FROM AUTHOR]

In engineering practice, the output performance of contact separation TENGs (CS‐TENGs) increases with the increase of tribo‐pair area, which includes increasing the size of single layer CS‐TENGs (SCS‐TENGs) or the number of units (zigzag TENGs). However, such two strategies show significant differences in output power and power density. In this study, to seek a universal CS‐TENG design solution, the output performance of a SCS‐TENG and a zigzag TENG (Z‐TENG) is systematically compared, including voltage, current, transferred charge, instantaneous power density, and charging power density. The relationship between contact area and output voltages is explored, and the output voltage equation is fitted. The experimental results reveal that SCS‐TENGs yield better performance than Z‐TENGs in terms of voltage, power, and power density under the same total contact area. Z‐TENGs show energy loss during the transfer of mechanical energy, and such loss is aggravated by the increasing number of units. The instantaneous peak power of the SCS‐TENG is up to 22 times that of the Z‐TENG (45 cm2). Furthermore, the power density of capacitor charging of SCS‐TENGs is 131% of that of Z‐TENGs, which are relatively close. Z‐TENG is a feasible alternative when the working space is limited. [ABSTRACT FROM AUTHOR]

Lithium‐ion insertion/deinsertion in anode at slow rates limits the power performance of energy storage devices. Here, a new pseudocapacitive electrode with high reversible capacity during cycling has been proposed for a lithium‐ion capacitor. The lithium‐fluoride garnet, namely Na3Fe2Li3F12, is obtained via precipitation from an aqueous solution at room temperature using abundant materials and exhibits a high discharge capacity of 746 mAh g−1. After the first charging cycle, the energy is stored via fast pseudocapacitive faradaic reactions which are facilitated by the nanocrystalline transport pathways with no structural modification to the electrode. The high stability window of F‐garnet allows extracting cell voltages of 2.2–3.2 V in a lithium‐ion capacitor where it is coupled with a porous carbon‐based positive electrode, with a high energy efficiency of 93 % maintained for 10000 charge/discharge cycles. This study opens a new research direction concerning pseudocapacitive anode materials for enhancing power performance and even replacing the traditional battery‐like anode materials. [ABSTRACT FROM AUTHOR]

This paper introduces one-cycle control (OCC) for reduced-DC-voltage-fed three-leg converter for single-phase active filtering and reactive compensation. The proposed power circuit configuration uses six switches (and associated gate drive circuits) and provides a better performance compared to eight-switch version (four-leg) in terms of reduced component count. It has lower semiconductor loss and lower high-frequency distortion in the grid current compared to four-switch version (two-leg). The proposed closed-loop control exhibits grid voltage sensor-less operation with effective compensation of nonlinear/reactive loads (IEEE 519-2022 compatible) and resonance damping of the filter network within the converter. Moreover, the reactive power drawn by the capacitor causes a slight deviation in the reactive power operation. An additional compensation term along with resonance damping term is incorporated in the OCC to overcome this problem. A detailed comparison of semiconductor losses among two-leg, three-leg, four-leg configurations is carried out using PLECS software. The proposed concept is verified through simulation studies. [ABSTRACT FROM AUTHOR]

A direct-current microgrid (MG) can be susceptible to extremely high fault currents contributed by the output filter capacitors of power converters and can also face protection challenges because of the non-zero crossing of fault currents. In a Low-Voltage Direct Current (LVDC) MG, low-fault-tolerance converters such as boost converters and bidirectional converters mostly require a fast and adaptable fault protection scheme that can detect and clear quickly faults irrespective of a wide range of fault impedances in the system. Several current- and voltage-derivative-based protection methods with communication support have been developed to primarily protect DC MGs due to their high sensitivity and selectivity. Overcurrent and under-voltage-based protection schemes are mostly suggested as backup protections for the DC MGs. To accurately detect and rapidly clear the faults even in the case of communication failure from the primary protection, this paper proposes a novel backup fault protection scheme with high selectivity, adaptability, and scalability for islanded LVDC MGs based on local measurements along with Chi-squaredistribution-based statistics. Specifically, this developed backup protection not only applies a cumulative summation methodology for the locally measured signals to extract derivative and integral characteristics of the current and voltage, but also uses the Chi-square-distribution-based statistics to consistently calculate tripping thresholds for the effective detection of different fault events in the LVDC MG, regardless of variable fault resistances and the communication-link damage. As a result, the proposed backup protection is capable of accurately detecting various DC faults to secondarily protect the source and load branches of the system within the expected time frame of a few milliseconds and has been validated through multiple staged fault tests from an off-grid and ungrounded 1kW and 48VDC MG testbed. [ABSTRACT FROM AUTHOR]

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Abstract Film capacitors are playing an increasingly important role in power‐related fields, driven by the continuous development of dielectric materials and practical needs. Long‐term accumulation has also led to an increasing wealth of data related to film capacitors. Sonification opens up a new way for people to make good use of data from film capacitors. A framework for sonifying film capacitors data based on TwoTone is presented. Based on the analysis and discussion, it is clear that the sonification results can easily represent the monotonic variation pattern of film capacitors data. What's more, the sonification results increase the possibility that people pay attention to the changing trend of film capacitors data when there is no significant difference in the visual perception of the data. In addition to providing a new way of music generation of electrical equipment, the method proposed is expected to contribute to theory reference in typical scenarios, such as factory calibration of film capacitors, monitoring of film capacitor operation status, and presentation of statistical data of film capacitors' dielectric materials, which will help us to better understand the distribution characteristics of polymer films.

A grid-forming wind generation system exhibits exceptional grid frequency support abilities. The DC capacitor of the grid-forming wind generation system, which is characterized by rapid response and high sensitivity to minor disturbances, can provide short-term inertia support for the power system. This paper proposes the capacitor virtual inertia control for the grid-forming wind generation system, coupling the DC capacitor voltage with the power system frequency, which enables the DC capacitor to participate in the system frequency response process and reduces the rate of change of the system frequency during the disturbance. To analyze the inertia of the wind power generation system, this paper establishes an equivalent Philips-Heffron model for the grid-forming wind generation system and uses the equivalent inertia constant to quantify the inertia of the wind power generation system. The effectiveness of the proposed control strategy and the reasonableness of the inertia assessment method are verified through simulations in the single-turbine system and the IEEE four-machine two-area system. [ABSTRACT FROM AUTHOR]

The burgeoning significance of antiferroelectric (AFE) materials, particularly as viable candidates for electrostatic energy storage capacitors in power electronics, has sparked substantial interest. Among these, lead-free sodium niobate ( N a N b O 3 ) AFE materials are emerging as eco-friendly and promising alternatives to lead-based materials, which pose risks to human health and the environment, attributed to their superior recoverable energy density and dielectric breakdown strength. This review offers an insightful overview of the fundamental principles underlying antiferroelectricity and the applications of AFE materials. It underscores the recent advancements in lead-free N a N b O 3 -based materials, focusing on their crystal structures, phase transitions, and innovative strategies devised to tailor their electrostatic energy storage performance. Finally, this review delineates the prevailing challenges and envisages future directions in the realm of N a N b O 3 -based electrostatic energy storage capacitors, with the goal of fostering further advancements in this pivotal field. [ABSTRACT FROM AUTHOR]

8/20 µs lightning pulse current generators (LPCG) used in testing surge arresters require a laborious production process that needs a high budget. An easily repairable, portable, and affordable test system with a maximum energy of 2.9 kJ and a voltage level of 24 kV that can alter its parameter values was described in this work. Simulation and experimental studies were carried out to investigate the effects of the resistor and coil elements in the Pulse Current Generator (PCG) circuit on the amplitude, front, and tail time of the pulse current. Most components of the experimental system were created using 3D printing technology with polylactic acid (PLA) material. The production costs were significantly reduced, according to equivalent pulse generators. Tests at different pulse currents and voltage levels were performed with the experimental system. Power capacitors may often fail due to overvoltage, switching, and partial discharge reasons. The high voltage (HV) power capacitors used in the pulse generator introduced in the study were obtained with the help of low voltage capacitor stacks. As a result, a less expensive, high-capacity capacitor system that is easily and quickly repairable in case of failure was achieved. [ABSTRACT FROM AUTHOR]

Dielectric energy storage capacitors are promising avenues for high power density and fast charge/discharge applications. This study focused on the deposition of Bi 3.25 La 0.75 Ti 3 O 12 (BLT) films onto Pt/Ti/SiO 2 /Si substrates by a sol-gel technology. Through the synergistic strategy of interface engineering and the preferred orientation of BLT film, the residual polarization was minimized, and the breakdown field strength was enhanced. As a result, the recoverable energy density (U rec) was significantly improved to 62.97 J/cm3 with a high energy storage efficiency (η) of 85.88 %. Notably, the synthesized BLT film exhibited excellent temperature (25–150 °C) and frequency (100 Hz-10 kHz) stability of U rec (>30 J/cm3) and η (>75 %) at ∼2200 kV/cm. The finding demonstrates the potential of BLT thin film as a lead-free material for the next generation of pulse power capacitors. Overall, the synergistic approach of interface engineering and preferred orientation proves to be an effective way to improve the performance of dielectric energy storage capacitors. [ABSTRACT FROM AUTHOR]

A-site vacancy-engineered Ba0.015+1.5xSr0.245-1.5x□0.03Bi0.385Na0.325TiO3 (B0.015+1.5x S0.245-1.5x□0.03BNT, x = 0, 0.012, 0.024, 0.036, 0.048, 0.06) ceramics were fabricated by a solid-state reaction method. The effect of Ba/Sr regulation on the structure, polarization, and dielectric energy storage properties of the B0.015+1.5xS0.245-1.5 x□0.03BNT ceramics were investigated. With the increase of the x value, the lamellar microdomains transform into the coexistence of banded domains and nanodomains. A double-like P-E hysteresis loop with a high polarization value (Pmax > 35 μC/cm²) can be obtained at a very low electric field of 60 kV/cm. Consequently, a large recoverable energy storage density (Wrec = 2.33 J/cm³) can be achieved at a relatively low applied electric field of 130 kV/cm. The designed B0.087S0.173□0.03BNT also exhibits high dielectric constant (εr = 3510 @150°C&1 kHz) with suitable temperature capacitance coefficient (TCC150°C = ±15%) over the temperature range of 17°C~382°C. These findings provide a novel vacancy-engineered avenue towards the design of BSBNT relaxor ceramics with high Wrec and good stability for low-voltage driven high-temperature pulsed power capacitor. [ABSTRACT FROM AUTHOR]

Introduction: Virtual Synchronous Generators (VSGs) are used in Voltage Source Converter-based Multi-Terminal High-Voltage Direct Current (VSC-MTDC) systems to enhance power system stability. However, the MTDC framework can lead to instability due to reduced inertia in certain grid areas, especially during load switching at VSC stations. This instability is exacerbated by untimely adjustments of the VSG's power setpoint, leading to voltage and frequency oscillations. Methods: This study introduces a cooperative control approach for the DC voltage of the VSG, employing a consensus algorithm and Model Predictive Control (MPC). This method aims to achieve incremental power for the VSG and provide interactive power commands for both the grid side and the wind farm side. The consensus algorithm ensures coherent system adjustments, while the MPC algorithm tracks DC-side voltage changes in real time. Results: The application of this cooperative control approach significantly enhances DC voltage regulation performance. It effectively reduces the extent of frequency drops and mitigates secondary frequency drop (SFD) issues, particularly those arising from the use of wind farms for frequency regulation and the associated speed recovery in wind turbine units. Discussion: The increase in supplemental power effectively utilizes the energy stored in DC-side capacitors for power balance regulation and introduces additional inertial power into the system. Electromagnetic transient simulations have confirmed the effectiveness of the Consensus MPC-VSG method, demonstrating its ability to optimize the dynamic performance of VSC-MTDC systems and promote stability in DC voltage and frequency. Conclusion: The findings suggest that employing the Consensus MPC-VSG method offers a promising solution for enhancing the stability and operational efficiency of VSC-MTDC systems, addressing the challenges posed by the inherent segmentation of the grid and the integration of renewable energy sources like wind farms. [ABSTRACT FROM AUTHOR]

Abstract The authors propose a current fluctuation reduction strategy based on optimal three‐space‐vector pulse‐width modulation (TSVPWM), which is used to improve the service‐life of the dc‐link electrolytic capacitors in two‐level three‐phase voltage‐source inverter (VSI) system. Differing from the typical SVPWM‐based method that employs two adjacent active voltage vectors and zero voltage vectors to synthesise the reference voltage, the proposed strategy selects the required voltage vectors based on the minimum dc‐link electrolytic capacitor current fluctuation. With the proposed strategy, an objective function for the root‐mean‐square value of dc‐link electrolytic capacitor current is first constructed under the constraint of eight permissible voltage vectors. And then, by solving the minimum of the objective function through the piecewise linear programming, the optimal three voltage vectors under the different modulation ratios and load power factors are obtained accordingly, so as to achieve the minimum dc‐link electrolytic capacitor current fluctuations during each switching period. Meanwhile, a PWM implementation scheme based on positive–negative double carrier signals is presented, which not only simplifies the implementation process but also effectively reduces the switching losses of power devices. Finally, the experimental results demonstrate that the proposed strategy can minimise the dc‐link electrolytic capacitor current fluctuation under different working conditions.

Simultaneously achieving high energy density and high‐power density in energy storage systems is a crucial direction for developing next‐generation energy storage technologies. The high capacity and rapid kinetic performance of rechargeable proton batteries provide an ideal solution for overcoming energy limitation of capacitors and power constraints of traditional metal‐ion batteries. Research efforts primarily concentrated on electrode materials design, understanding the charge storage mechanisms, and exploring the failure mechanisms. While there has been relatively less emphasis on the modifications to electrolytes and electrode‐electrolyte interfaces to enhance overall performance. Summarizing and sorting relevant work is crucial in providing direction and suggestions for future research endeavors. Herein, to improve energy density, power density, and cycle stability of proton batteries, a series of recently published studies on electrolyte and electrode‐electrolyte interfaces are discussed and reviewed. Furthermore, challenges and future directions pertaining to the electrolytes of proton batteries have been identified, offering insights to facilitate the development of proton battery technology. [ABSTRACT FROM AUTHOR]

The authors propose a current fluctuation reduction strategy based on optimal three‐space‐vector pulse‐width modulation (TSVPWM), which is used to improve the service‐life of the dc‐link electrolytic capacitors in two‐level three‐phase voltage‐source inverter (VSI) system. Differing from the typical SVPWM‐based method that employs two adjacent active voltage vectors and zero voltage vectors to synthesise the reference voltage, the proposed strategy selects the required voltage vectors based on the minimum dc‐link electrolytic capacitor current fluctuation. With the proposed strategy, an objective function for the root‐mean‐square value of dc‐link electrolytic capacitor current is first constructed under the constraint of eight permissible voltage vectors. And then, by solving the minimum of the objective function through the piecewise linear programming, the optimal three voltage vectors under the different modulation ratios and load power factors are obtained accordingly, so as to achieve the minimum dc‐link electrolytic capacitor current fluctuations during each switching period. Meanwhile, a PWM implementation scheme based on positive–negative double carrier signals is presented, which not only simplifies the implementation process but also effectively reduces the switching losses of power devices. Finally, the experimental results demonstrate that the proposed strategy can minimise the dc‐link electrolytic capacitor current fluctuation under different working conditions. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Tecnologia Aplicada is the property of Faculdade Campo Limpo Paulista and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study concerns problems related to the assessment of reactive power in power networks with nonlinear fast-varying loads, such as electric arc furnaces, rolling mill drives, etc. The operation of this type of load is characterized by the introduction of interharmonic currents (including higher harmonics) into the power supply network and a relatively low power factor. Rapid changes in the RMS value of the current also cause voltage fluctuations and the related phenomenon of light-flickering. Therefore, there is a need to evaluate the power selection of compensating devices, taking into account the random nature of load changes and the distortion of current and voltage waveforms, in particular, interharmonic components, the impact of which has not been fully investigated so far. To analyze the random nature of load changes, autocorrelation functions were used, which allowed for the estimation of the expected values of the arc furnace current distortion coefficient (based on the recorded waveforms). In order to determine the parameters of reactive power compensating devices, and in particular capacitor banks, an autocorrelation function in the exponential-cosine-sine form was used, which meets the conditions of differentiation. This study contains comparative results of the reactive power of capacitor banks determined using different methods. The criterion for selecting capacitor bank parameters was the minimization of energy losses in the power supply network. The calculations presented in this study show that by taking into account higher harmonics and interharmonics in the voltage and currents of fast-varying loads, the installed power of the capacitor bank can be reduced by approximately 7%, and energy losses in the power grid can be reduced by 3–5%. [ABSTRACT FROM AUTHOR]

The uneven load of the electric drive of sucker-rod pumping units causes an increase in the consumption of reactive power, which requires compensation. This article discusses the issue of calculating the processes in sucker-rod pumping units in the case of individual compensation of the reactive power. Mathematical models for calculating the process of changing the capacity of cosine capacitors for reactive power compensation in the starting and steady-state modes of the electric drive of the sucker-rod pumping unit, which are characterized by the periodically varying load and moment of inertia, have been developed. The calculation is based on a mathematical model of the induction motor that takes into account the saturation of the magnetic path and the skin effect in the bars of the deep-bar rotor. The created mathematical model can be used to regulate the capacitance of the capacitors connected to the induction motor in order to reduce the reactive power consumption. [ABSTRACT FROM AUTHOR]

The application of modular multilevel converters (MMCs) to large drive systems is subject to severe low-frequency operation restrictions. The fluctuation of capacitor voltage and the high amplitude of common mode voltage in sub-modules is a thorny problem. In this paper, a novel fly-across capacitor modular multilevel converter topology is adopted to eliminate low-frequency voltage ripples by using the fly-across capacitor as a power transfer channel between the upper and lower bridge arms of the MMC. A novel finite compensation method is proposed--instead of the traditional full compensation method--that introduces a real-time variable limiting factor to change the amplitude of the mixed injected high-frequency differential-mode voltage and high-frequency differential-mode current and reduce the amplitude of the common-mode voltage on the AC side while lowering the current stress of the power devices. Finally, a complete system simulation model is constructed, and the topology with the proposed control strategy are verified to have good output characteristics under different operating conditions; good results are achieved in suppressing the sub-module fluctuation and common-mode voltage. [ABSTRACT FROM AUTHOR]

Single Source Cross Connected Reduced Activated Switched-Capacitor Multilevel Inverter (S²C²RASCMLI) accompanied by fewer active switching components is appealing to nine-level of voltage with its simplicity and a solid network. In AC power distribution systems, multi-level inverters are used as DC-to-AC converter operations to achieve the desired output magnitude and frequency. It is employed for the smooth operation of electrical machines. The proposed S²C²RASCMIL cell yields a nine-level voltage with ten switches, nine driver signals, and two flying capacitors for dynamic load operation with reduced active switches. It has the capability of boosting the input voltage double the times. The proposed multilevel inverter operated on nine switching modes and in each mode, three switches have been conducted. It can be extended horizontal and/or vertical structure to produce more levels of output voltages. The hardware prototype was made and the results have been presented. To demonstrate the advantages of the new proposed multilevel inverter topology, a comprehensive comparison with a few other similar multilevel inverter configurations is done. Analysis and simulation output waveforms for a variety of load conditions were tested to check the feasibility of the proposed new multi-level inverter. The proposed MLI offers better performance than existing multilevel inverters. [ABSTRACT FROM AUTHOR]