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Dielectric materials with significant performance in high temperatures are highly desired, especially in harsh environments. However, the polymer‐based dielectric films have developed so far, the production scale remains at the state of the lab. Here, an all‐organic strategy is proposed by introducing phenyl‐acid‐based polymer nanodots (PAPD) into Polyetherimide (PEI), achieving high capacitive energy storage properties even at 200 °C and mass production by an industrial continuous roll‐to‐roll process. The abundant hydrogen bonding between PAPD and PEI chains ensures uniform distribution for the enhanced interaction between nanofillers and polymer matrix. Under UV irradiation, the electron‐affinity and band gap of the film are further extended, which impede charge transfer and reduction of conductive loss. A low loading (0.3 wt.%) of PAPD renders the membrane significant improvement in breakdown strength and charge–discharge efficiency. An ultrahigh energy storage density of 5.1 J cm−3 with a charge–discharge efficiency of over 90% and charge–discharge cycle stability up to 2 × 104 cycles at 150 °C is observed. Furthermore, a 1000 m long roll of polymeric film is roll‐to‐roll fabricated on an industrial solution‐casting production line and the low cost makes practical commercial scale application possible. Considering the low loading and low cost of nanofiller, this all‐organic design strategy sheds light on the industrial application of high‐temperature dielectric materials. [ABSTRACT FROM AUTHOR]

An analysis of the transient processes during aperiodic charging of the capacitive energy storage (CES) of the electri-cal discharge installation (EDI) from the source of direct voltage (SDV) of the USDV was carried out under the condition of changing the initial voltage of the CES at the time of the start of charging. The dependences of energy characteristics (dose of energy that powers the capacitor, energy losses and efficiency) on the magnitude and sign (polarity) of the ini-tial voltage CES were obtained. The energetically appropriate CES charge modes were determined. It is substantiated that increasing the initial voltage of the capacitor leads to an increase in the charging efficiency. The analysis of the ratio between the dose of energy that powers the CES during one charge cycle W*C and the energy of losses W*losses showed that the ratio W*C / W*losses increases with a change in the voltage U0C from –USDV to + USDV due to the fact that the energy of losses W*losses decreases faster than the dose of energy that powers the CES. Ref. 11, fig. 3, table.

High‐temperature dielectric polymers are in high demand for powering applications in extreme environments. Here, we have developed high‐temperature homopolymer dielectrics with anisotropy by leveraging the hierarchical structure in semicrystalline polymers. The lamellae have been aligned parallel to the surface in the dielectric films. This structural arrangement resembles the horizontal alignment of nanosheet fillers in polymer nanocomposites and nanosheet‐like lamellae in block copolymers, which has been proven to provide the optimal topological structure for electrical energy storage. The unique ordering of lamellae in our dielectric films endue a significantly increased breakdown strength and a reduced leakage current compared to amorphous films. This novel approach of enhancing the capacitive energy storage properties by controlled orientation of lamellae in homopolymer offers a new perspective for the design of high‐temperature polymer dielectrics. [ABSTRACT FROM AUTHOR]

Previous studies propose that NH4+ storage in metal oxides and metallic ion storage using Poly(3,4‐ethylenedioxythiophene) (PEDOT) both undergo diffusion‐controlled processes. This study, employing experimental and simulation studies, reveals that flower‐like PEDOT shells predominantly store NH4+ ions storage through surface‐controlled processes, constituting over 80 percent of the overall storage. NH4+ ions interact with PEDOT′s π–π stacking via van der Waals interactions, circumventing ionization energy and entropy barriers. Additionally, the controlled polymerization and crystallinity of PEDOT contribute significantly to this storage process. The reduction in lamellar packing distance and face‐to‐face distance between the molecular chains, coupled with an increase in crystalline domains, intensifies inter‐chain weak interactions and extends the overlap length of wave functions. These findings offer a comprehensive insight into cation storage using organic polymers. [ABSTRACT FROM AUTHOR]

AbstractAs a key material for capacitors, high-performance polymer dielectric films still exhibit the problem of low energy storage density, which cannot meet the requirements of high-power and high-temperature conditions. Here, a sandwich-structured composite film with inner layer doped TiO2-BCB (titanium dioxide – benzocyclobutene) and outer layer doped BN-BCB (boron nitride – benzocyclobutene) nanoparticles was prepared, which exhibits reduced dielectric loss, leakage current and enhanced dielectric constant (ε) and breakdown strength (Eb). Diels-Alder reaction and radical polymerization reactions are utilized to form the entire cross-linked sandwich structure. Moreover, the thermal-induced crosslinked structure replaces the traditional multilayer structure established by Van der Waals forces, thus improving the dielectric and mechanical qualities of the film. Specifically, the sandwich structure composites achieved a large discharge energy density (4.0 J/cm3) and high charge-discharge efficiency (84%) at 150 °C and 450 MV/m, and the dielectric dissipation factor is less than 0.005. These results demonstrated that designing a cross-linked network in multilayer nanocomposite structure is a feasible method to improve the high-temperature energy storage performance of these films.

As a key material for capacitors, high-performance polymer dielectric films still exhibit the problem of low energy storage density, which cannot meet the requirements of high-power and high-temperature conditions. Here, a sandwich-structured composite film with inner layer doped TiO2-BCB (titanium dioxide – benzocyclobutene) and outer layer doped BN-BCB (boron nitride – benzocyclobutene) nanoparticles was prepared, which exhibits reduced dielectric loss, leakage current and enhanced dielectric constant (ε) and breakdown strength (Eb). Diels-Alder reaction and radical polymerization reactions are utilized to form the entire cross-linked sandwich structure. Moreover, the thermal-induced crosslinked structure replaces the traditional multilayer structure established by Van der Waals forces, thus improving the dielectric and mechanical qualities of the film. Specifically, the sandwich structure composites achieved a large discharge energy density (4.0 J/cm3) and high charge-discharge efficiency (84%) at 150 °C and 450 MV/m, and the dielectric dissipation factor is less than 0.005. These results demonstrated that designing a cross-linked network in multilayer nanocomposite structure is a feasible method to improve the high-temperature energy storage performance of these films. [ABSTRACT FROM AUTHOR]

Integration of renewable energy sources (RESs) in modern power system has put a great challenge on researchers and system engineers to satisfactorily operate the power system when it is subjected to various disturbances. Automatic generation control (AGC) plays a very essential role in modern power system to control the tie‐line power flows and system frequencies. This paper illustrates about optimal design and implementation of various controllers for AGC of a two‐area non‐reheat thermal power system with some supplementary generation from dish stirling solar thermal system and wind‐turbine system. In addition to the generating sources, some energy storage systems like capacitive energy storage and redox flow battery are integrated to improve the dynamic stability of the system. Various controllers like fuzzy logic based PID controller, PID controller with filter (PIDF) and fuzzy PIDF (1 + PI) controller are used as supplementary controllers of the AGC system. The proposed controllers are optimally designed by FBI algorithm and QO‐FBI algorithm. A step load of 1% (0.01 pu) is applied in area‐1 to analyze the performances of the proposed controllers. Investigation of the study includes undershoot, overshoot and settling time of frequency and tie‐line power deviations. The percentage improvement of QO‐FBI based FPIDF (1 + PI) controller with respect to ICA based FPIDF (1 + PI) controller is examined. It is noticed that, AGC system equipped with QO‐FBI based FPIDF (1 + PI) controller outperforms ICA‐FPIDF (1 + PI) controller in all aspects. The superiority of the QO‐FBI based FPIDF (1 + PI) controller is validated under parametric variation in system parameters. Sensitivity analysis is also carried out by varying the inputs to the intermittent renewable sources. Comparative performance analysis reveals that QO‐FBI based FPIDF (1 + PI) controller performs better in comparison with other proposed controllers and a recently proposed ICA based FPIDF (1 + PI) controller. [ABSTRACT FROM AUTHOR]

The bottleneck in the implementation of hybrid lithium-sodium-ion batteries is the lack of anode materials with a desired rate capability. Herein, we provide an in-depth examination of the Li-storage performance of sodium titanate nanowires as negative electrodes in hybrid Li,Na-ion batteries. Titanate nanowires were prepared by a simple and reproducible hydrothermal method. At a low reaction pressure, the well-isolated nanowires are formed, while by increasing the reaction pressure from 2 to 30 bar, the isolated nanowires tend to bundle. In nanowires, the local coordinations of Na and Ti atoms deviate from those in Na2Ti3O7 and Na2Ti6O13 and slightly depend on the reaction pressure. During the annealing at 350 °C, both Na and Ti coordinations undergo further changes. The nanowires are highly defective, and they easily crystallize into Na2Ti6O13 and Na2Ti3O7 phases. The lithium storage properties are evaluated in lithium-ion cells vs. lithium metal anode and titanate electrodes fabricated with PVDF and carboxymethyl cellulose (CMC) binders. The Li-storage by nanowires proceeds by a hybrid capacitive-diffusive mechanism between 0.1 and 2.5 V, which enables to achieve a high specific capacity. Sodium titanates accommodate Li+ by formation of mixed lithium-sodium-phase Na2−xLixTi6O13, which is decomposed to the distinct lithium phases Li0.54Ti2.86O6 and Li0.5TiO2. Contrary to lithium, the sodium storage is accomplished mainly by the capacitive reactions, and thus the phase composition is preserved during cycling in sodium ion cells. The isolated nanowires outperform bundled nanowires with respect to rate capability. [ABSTRACT FROM AUTHOR]

Modern power system has complex composition structure and high stability operation requirements. While the emergence of various new energy sources and the uncertainty of external disturbances bring a great challenge to the Automatic Generation Control (AGC) of power system. In order to improve the robustness of the AGC and facilitate the practical engineering application, this paper proposes a novel structure multistage Proportional Integral Derivative (PID) cascade automatic generation controller as well as an improved more effective control parameter optimization algorithm. Firstly, a two-area multi-unit multi-source hydro/thermal power system containing with capacitive energy storage unit is modeled. And using double closed-loops control method, a PID controller with derivative Filter and 1+Proportional Integral unit (PIDF-(1+PI)) cascade automatic generation controller is proposed. Secondly, by introducing a nonlinear time-varying adaptive weight factor, an improved Whale Optimization Algorithm (WOA-w) is proposed to accelerate the convergence speed and enhance the solution accuracy. Then, based on the integral of time multiplied absolute error (ITAE) objective function, the proposed PIDF-(1+PI) controller parameters are optimized by WOA-w. Finally, MATLAB/Simulink software is used to implement the control system multi-case simulation. Compared with other three control strategies, the multi-scenario cases simulation results verify the correctness and effectiveness of the proposed control strategy.

Ever-increasing electrification scenarios call for high energy density (Ue) polymer nanodielectric films beyond the commercial benchmark biaxially oriented polypropylene. Ferroelectric polymers of intrinsic high dielectric constant εr, if integrated with improved breakdown strength (Eb) and dielectric loss from nanofillers, would be a promising paradigm for high-Ue polymer nanodielectrics. Yet, this expectation is still in its infancy because of the great challenge of increasing the Eb and needs introduction of new approaches. Here, fluorographene (FG), as a young halogen derivative of graphene, is employed as an emerging nanofiller to develop high-Eb polymer nanodielectrics. A dramatically enhanced Eb, which is 39.4% higher than that of a neat polymer film from casting, is achieved in a composite film along with a reduced dielectric loss by incorporating only 0.2 wt % FG with in-plane orientation from electrospinning. The origin of such a high Eb-reinforcing effect of FG is traced by both experimental characterizations and phase-field simulation. It is found that the in-plane oriented FG of appropriate loading level would induce both the favorable low crystallinity of the polymer matrix and the FG–polymer interface with deep traps and less defects. This, together with the high out-of-plane insulation of FG from a high fluorine/carbon ratio, regulates the charge behaviors and breakdown paths and thus significantly enhances the voltage endurance of composite films. The results demonstrate the remarkable Eb-reinforcing effect of emerging FG fillers in polymer nanodielectrics and offer a strategy toward high-Eb/high-Ue flexible dielectric capacitors. [ABSTRACT FROM AUTHOR]

The rotational speed of a generator affects the frequency and voltage produced, where this change will affect the load side. For that we need a control equipment that can optimize the performance of micro-hydro. Therefore, we need a technology to optimize the performance of micro hydro by applying Load Frequency Control (LFC). LFC designed by implementing Superconducting Magnetic Energy Storage (SMES) and Capacitive Energy Storage (CES), this application will provide power compensation to reduce or even eliminate frequency oscillations caused by changes in consumer electrical power loads. To get optimal microhydro performance, it is necessary to set the right parameters for SMES and CES. SMES and CES parameter tuning in this study is proposed using the Bat Algorithm. The objective function used by this algorithm is to optimize the Integral Time Absolute Error (ITAE). For performance analysis, the system is tested with load changes, then the governor, turbine, and system frequency responses are analyzed. To test the reliability of the system, this study used several scenarios of a combination of control, SMES, CES, with conventional control based on Proportional, Integral, Derivative (PID). The right control parameters will improve system performance more optimally. Optimal system performance can be seen from the response of the governor, turbine, and minimum overshoot of the frequency, as well as the fast settling time for the system to switch to steady state conditions.

This paper presents an accomplishment of Load Frequency Control (LFC) under deregulated environment using Imperialistic Competition Algorithm (ICA) based Dual Mode Controller (DMC). The Capacitive Energy Storage (CES) and Static Synchronous Series Compensator (SSSC) have been successfully used to improve the performance of the system dynamics. The optimization techniques are beneficial to the design of the Dual Mode Controller and overcome the drawbacks identified by the conventional controllers. The traditional Load Frequency Control system is adapted to interpret bilateral contracts on the system. The performance index is calculated by using the integral of the square of error technique to optimize the controllers of the Load Frequency Control system. The simulation analysis reveals that due to the presence of the Imperialistic Competition Algorithm-based Dual-Mode Controller, the performance of the system improves in terms of peak time, settling time, and overshoot, and also performance index is lesser than the system without the Imperialistic Competition Algorithm based Dual Mode Controller following a load disturbance in either of the areas.

Featured Application: This work describes the thermal stability of thin films of tungsten nitrides in vacuum and can be useful in solar thermodynamic field for tailoring solar absorbers, capacitive energy storage devices and catalysts for hydrogen evolution reaction, and in fusion applications for plasma facing materials. In this work, tungsten nitrides sputtered at different powers supplied to a W target (300 W, 500 W, 700 W) and proposed for solar thermal applications as part of solar absorbers, as active and robust materials for capacity energy storage and as plasma-facing materials were annealed in vacuum at medium-high temperatures (470 °C, 580 °C) and characterized by means of X-ray diffraction (XRD), AFM, micro-Raman, FTIR, UV–VIS–-NIR, sheet, surficial energy and wetting angle measurements. From the overall set of analyses, some important modifications and differences between samples after annealing emerged (which will be useful for selecting them for specific applications) and have been correlated to sputtered W metallic clusters' ability to adsorb, form complexes with and react with the strong N2 triple bond under the various plasma conditions of a reactive sputtering process. In particular, the 300 W film of poor crystalline quality as deposited, after annealing released entrapped nitrogen and retained its W2N structure up to a temperature of 580 °C. Despite there being no phase transition, there was an increase in sheet resistance, which is detrimental because the preservation of metallic character is an important requisite for the proposed applications. The 500 W film had a stable crystalline structure and a metallic character unmodified by increasing temperature. The 700 W film, whose structure as deposited was almost amorphous, underwent the most severe modification after annealing: crystallizing, disproportioning and giving rise to a composite and porous nature (W + WNx) not ideal for spectrally selective coating applications, but useful for tailoring capacitive energy storage devices, or for catalysts for hydrogen evolution reactions (as an alternative to platinum) in alkaline water electrolysis. [ABSTRACT FROM AUTHOR]

The concept of automatic generation control has an immense role in providing quality power in an interconnected system. To obtain quality power by controlling the oscillations of frequency and tie-line power, a proper controller design is necessary. So, an innovative endeavor has been undertaken to enforce a two-stage controller with the amalgamation of a proportional-derivative with filter (PDN) (integer-order) and a fractional order integral-derivative (FOID), i.e., PDN(FOID). In an effort to acquire the controller's gains and parameters, a bio-inspired meta-heuristic spotted hyena optimizer is applied. Various examinations manifest the excellence of PDN(FOID) over other controllers such as integral, proportional–integral, proportional–integral-derivative filter, and fractional order PID from perspectives concerning the diminished amount of peak anomaly oscillations, and the instant of settling for a three-area system. The system includes thermal–bio-diesel in area-1; a thermal–geothermal power plant in area-2; and a thermal–split-shaft gas turbine in area-3. It is also observed that the presence of renewable sources such as wave power plants and photovoltaics makes the system significantly better compared to the base system, when assessed individually or both together. Action in a combination of capacitive energy storage with duple compensation is also examined using the PDN(FOID) controller, which provides a noteworthy outcome in dynamic performance. Moreover, PDN(FOID) parameter values at a nominal condition are appropriate for the random patterns of disturbance needed for optimization. [ABSTRACT FROM AUTHOR]

Holey graphene nanosheets are potentially useful in several relevant technological applications, including electrochemical energy storage and molecular separation. Access to this material is mostly accomplished by resorting to standard graphene oxides obtained by common routes (e.g., the Hummers method). However, such a type of highly oxidized graphenes may not be the best option as a precursor to holey graphene on account of their chemical/structural heterogeneity and harsh synthesis conditions. Here, we report the use of highly oxidized graphene nanosheets derived by an electrochemical exfoliation/oxidation strategy as an alternative precursor to holey graphene. Compared to a standard graphene oxide with the same extent of oxidation, the electrochemically derived precursor exhibited larger aromatic domains, which provided a structural basis for its higher electrical conductivity, as well as smaller and denser oxidized regions, associated to a higher chemical homogeneity and lability of its oxygen-containing functional groups. Through selective chemical etching of the oxidized domains, the latter feature was exploited to afford holey graphene nanosheets having smaller and more uniform holes. When used as an electrode material for electrochemical charge storage, the electrochemically derived holey graphene outperformed its standard graphene oxide-based counterpart in terms of capacity and energy density. Overall, boasting distinct structural and chemical characteristics, highly oxidized graphene obtained by electrochemical means can be regarded as a prospective advantageous precursor to many graphene-based materials whose preparation has traditionally relied on the processing of graphene oxides. [Display omitted] • Electrochemically-derived highly oxidized graphene is a proper precursor to holey graphene. • Anodic graphene offers advantages as precursor for holey graphene over graphene oxide. • Electrodes based on this new type of holey graphene exhibit improved capacity and energy density. [ABSTRACT FROM AUTHOR]

Polymer nanocomposites hold great potential as dielectrics for energy storage devices and flexible electronics. The structural architecture of the nanofillers is expected to play a crucial role in the fundamental mechanisms governing the electrical breakdown and dielectric properties of the nanocomposites. However, the effect of nanofiller structure and dimensionality on these properties has not been studied thoroughly to date. This study explores the critical relationship between nanofiller dimensionality and dielectric properties in polymer nanocomposites. We fabricated polyvinylidene fluoride (PVDF) nanocomposites by incorporating a range of carbon-based nanofillers separately, including zero-dimensional (0D) carbon black (CB), one-dimensional (1D) multiwalled carbon nanotubes (MWCNT), 1D single-walled carbon nanotubes (SWCNT), two-dimensional (2D) reduced graphene oxide (rGO), and three-dimensional (3D) graphite. The frequency-dependent (1 kHz to 1 MHz) dielectric permittivity ( k ) of the nanocomposites at the same concentration of nanofillers demonstrated a hierarchical order, with MWCNT showing the highest permittivity (∼400%), succeeded by rGO (∼360%), CB (∼290%), SWCNT (∼230%), and graphite (∼70%), respectively. The temperature-dependent (50-150 °C) dielectric spectroscopy revealed high k with increasing temperature due to the enhanced dipole movement. However, their dielectric breakdown strength and energy densities were not correlated to k and exhibited the following order: SWCNT > MWCNT > CB > rGO > graphite. As the electrical breakdown depends upon the nanocomposites' mechanical strength, we correlated the mechanical properties with the nanofiller dimensionality, and Young's modulus followed the 1D ≈ 2D > 0D > 3D order. These findings will provide fundamental insights into designing tunable, conducive nanofiller-based nanocomposites in next-generation flexible electronics and capacitive energy storage devices.

Intercalating linear-organic-ions into the MoS 2 interlayer is beneficial for optimizing electrons/ions' capacitive storage behavior. The chain length, as an important parameter of linear organic ions, can lead to differences in the dispersion, polarity, critical micelle concentration of organic ions, and steric hindrance to the growth of MoS 2 nanosheets. Up until now, the relationship between chain length, synthesis of intercalated-MoS 2 , and capacitive energy storage has not been unveiled. Herein, we have designed an in situ-intercalation route that is simple, efficient, and high yield for inserting four types of linear organic ions into the interlayer of MoS 2 to synthesize four types of in situ-intercalated MoS 2 samples. After organic-ion intercalation, the expanded interlayer spacing achieved the introduction of intercalation-type pseudocapacitors, as confirmed by ex situ XRD. Improved extra capacitance is verified due to the enlarged ion storage space from a synergistic spatial effect in the broken-shell-hollow ball. Additionally, the generation of high-valent Mo (+5 and +6) and S-vacancies is beneficial for energy storage. More importantly, according to density functional theory (DFT) calculations, as the chain length increases, the number of negative adsorption sites and the total adsorption ability also increase, leading to significantly improved specific capacitance. This work will provide an archetype for the preparation of in situ-intercalated layered materials and unveil capacitive energy storage that relies on the organic-ion chain length.

The bottleneck in the implementation of hybrid lithium-sodium-ion batteries is the lack of anode materials with a desired rate capability. Herein, we provide an in-depth examination of the Li-storage performance of sodium titanate nanowires as negative electrodes in hybrid Li,Na-ion batteries. Titanate nanowires were prepared by a simple and reproducible hydrothermal method. At a low reaction pressure, the well-isolated nanowires are formed, while by increasing the reaction pressure from 2 to 30 bar, the isolated nanowires tend to bundle. In nanowires, the local coordinations of Na and Ti atoms deviate from those in Na2Ti3O7 and Na2Ti6O13 and slightly depend on the reaction pressure. During the annealing at 350 °C, both Na and Ti coordinations undergo further changes. The nanowires are highly defective, and they easily crystallize into Na2Ti6O13 and Na2Ti3O7 phases. The lithium storage properties are evaluated in lithium-ion cells vs. lithium metal anode and titanate electrodes fabricated with PVDF and carboxymethyl cellulose (CMC) binders. The Li-storage by nanowires proceeds by a hybrid capacitive-diffusive mechanism between 0.1 and 2.5 V, which enables to achieve a high specific capacity. Sodium titanates accommodate Li+ by formation of mixed lithium-sodium-phase Na2−xLixTi6O13, which is decomposed to the distinct lithium phases Li0.54Ti2.86O6 and Li0.5TiO2. Contrary to lithium, the sodium storage is accomplished mainly by the capacitive reactions, and thus the phase composition is preserved during cycling in sodium ion cells. The isolated nanowires outperform bundled nanowires with respect to rate capability.

Dielectric polymers are the materials of choice for high energy density film capacitors. The increasing demand for advanced electrical systems requires dielectric polymers to operate efficiently under extreme conditions, especially at elevated temperatures. However, the low permittivity and relatively low operating temperature of dielectric polymers limit the high-temperature capacitive energy storage applications. Fortunately, dipolar glass polymers are demonstrated as the preferred materials to achieve high dielectric constant, low dielectric loss and high energy density at elevated temperatures. In this review, we critically elaborate on the recent progress of dipolar glass polymers based on orientational polarization from molecular engineering. In addition, the general design considerations and various dipole moment entities of dipolar glass polymers are described in detail. High dipolar moment, high dipole density and rotation freedom of dipoles are essential for dipolar glass polymers to gain superior dielectric and energy storage properties. Challenges and future opportunities for dipolar glass polymers towards high-temperature energy storage applications are also provided. [ABSTRACT FROM AUTHOR]

The authors propose and substantiate the functionality of a magnetic-pulse installation consisting of two blocks, the first of which is a resonant double-circuit charger of a capacitive energy storage, and the second block is a discharge circuit with an inductor-tool for performing a given production operation. It is shown that the voltage changes in time according to an exponentially growing harmonic law. It was found that the amplitude of the voltage across the capacitor can be regulated by varying the characteristics of the coupling transformer between the circuits and the characteristics of the circuit of the reactive power conversion unit. Numerical assessments of the characteristics of the charging process showed a high efficiency of voltage formation on the capacitive storage due to resonance phenomena (the transformation ratio is equal to the Q-factor of the circuit ~ 20), which is not comparable with the well-known traditional indicators of induction methods. In terms of phase - the length in time to the maximum charge in the adopted circuit of the active electric power amplifier is set by the inequality - That is, after ~ 30 periods of charging current, the excited voltage reaches a maximum (~ 20 times higher than the source voltage), which will correspond to the end of the transient process and the establishment of a steady state of operation. An example of calculating the characteristics of an elementary resonant base illustrates the effective capabilities of a magnetic-pulse installation, consisting of a resonant charger of a capacitive energy storage and a load in the form of an inductor-tool for flat stamping of metal products. It was found that the square of the ratio of operating frequencies in the load unit and the reactive power amplification unit quantitatively determines the fundamental possibility of resonant amplification of the active electrical energy of a harmonic signal. [ABSTRACT FROM AUTHOR]

The pressing concerns of environmental sustainability and growing needs of clean energy have raised the demands of carbon and organic based energy storage materials to a higher level. Redox-active organic-carbon composites electrodes are emerging to be enablers for high-performance, high power and long-lasting energy storage solutions, especially for electrochemical capacitors (EC). This review discusses the electrochemical redox active organic compounds and their composites with various carbonaceous materials focusing on capacitive performance. Starting with the most common conducting polymers, we expand the scope to other emerging redox active molecules, compounds and polymers as well as common carbonaceous substrates in composite electrodes, including graphene, carbon nanotube and activated carbon. We then discuss the first-principles computational studies pertaining to the interactions between the components in the composites. The fabrication methodologies for the composites with thin organic coatings are presented with their merits and shortcomings. The capacitive performances and features of the redox active organic-carbon composite electrodes are then summarized. Finally, we offer some perspectives and future directions to achieve a fundamental understanding and to better design organic-carbon composite electrodes for ECs.

Purpose. An experimental verification of the existence of a range of values for the parameters of the capacitive energy storage of the magnetic-pulse installations with controlled vacuum discharger, in which, with a high probability, there is a «cut» of the discharge current pulses and the expansion of cylindrical thin-walled tubular workpieces using an external coil. Methodology. High voltage magnetic-pulse installation of NTU «KhPI» with controlled vacuum discharger, multiturn coil with inside dielectrical die and inside aluminum alloy workpiece are used. The capacitance and charge voltage of capacitive energy storage are changed. Discharge current pulses are measured by Rogowski coil and the oscillograph. Results. Parts of complicated shape are made by expansion of cylindrical tubular workpieces with help of external coil. Pressed metallic tubular part is removable from inner dielectric rod. Originality. The frequency of «cut» pulse is defined by negative magnetic field pressure amplitude. It is shown that we must coordinate this frequency and charge voltage with capacitive storage parameters by high probability of pulse «cut». Practical value. It is shown how to use installations with controlled vacuum dischargers in magnetic forming technology based on «cut» pulses.

The paper reveals the electro-physical features of the formation of multi-channel pulse currents and fast-migrating electric sparks in the layer of current-conductive granules of electric-discharge installations (EDIs) with reservoir capacitors. Such features make it possible to increase many times the productivity of the electric-spark dispersion of metal granules during single discharge current of reservoir capacitors, which flows between the electrodes of EDIs. Theoretical substantiation and experimental confirmation of multi-channel spark discharges in the layer of conductive granules are presented. The influence of the capacitance and charge voltage of reservoir capacitors on the nature of transient processes in the discharge circuit of the EDIs is investigated. The dependence of the effective value of the active load resistance of the EDIs on the value of the pre-charge voltage of its reservoir capacitors and the value of its capacitances has been experimentally determined. It is proved that an increase in the averaged Q-factor of the discharge circuit with an increase in the charge voltage of the capacitor bank of EDI is caused by a decrease in the effective value of the active resistance of the layer of metal granules when spark-generating discharge currents flow through it. [ABSTRACT FROM AUTHOR]

Summary: This article presents the studies of automatic generation control (AGC) on a three‐area hydro‐thermal system under various loading conditions. The study at various loading conditions is investigated because the model parameter of steam and hydro depend on their generation schedule. A maiden attempt has been made to design a three degree of freedom tilt integral derivative (3DOF‐TID) controller as a secondary controller. Its gains are optimized using a novel bird swarm algorithm (BSA). Comparison of dynamic responses in a hydro‐thermal system with the proposed 3DOF‐TID reveals better performance over 2DOF‐TID, 2DOF‐PID controllers. It is also explored that the dynamic system responses are improved in thermal power plants and deteriorate in the hydropower plants when loading increases from its nominal values. Moreover, the dynamic system responses are analysed with the realistic dish‐Stirling solar thermal system (RDSTS) considering fixed and random solar insolations. The comparative analysis suggests that RDSTS with fixed insolation enhances system dynamics by 5.72% over random insolation. Further, the comparison of dynamic responses of the system with AC tie‐line and parallel AC/accurate high‐voltage direct (AHVDC) tie‐lines reveals that the system dynamics are improved with the parallel AC/AHVDC tie‐lines. Furthermore, the inertia is emulated in the parallel AC/AHVDC tie‐line using capacitive energy storage (CES), super magnetic energy storage (SMES) systems, and redox flow battery (RFB). Simulations show that the inertia emulated hydro‐thermal‐RDSTS system with RFB provides better dynamics. Sensitivity analysis suggests that 3DOF‐TID parameters values at nominal condition are appropriate for higher value of disturbance without need for optimization. [ABSTRACT FROM AUTHOR]

Conducting polymers (CPs), a significant class of electrochemical capacitor electrode materials, exhibit exceptional capacitive energy storage performance in aqueous electrolytes. Current research primarily concentrates on enhancing the electrical conductivity and capacitive performance of CPs via molecular design and structural control. However, the absence of a comprehensive understanding of the impact of molecular chain spatial order on ion/electron transport and capacitive performance impedes the development and optimization of advanced electrode materials. Here, a solvent treatment strategy is employed to modulate the molecular chain spatial order of PEDOT : PSS films. The results of electrochemical performance tests and Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) show that Poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonic acid) (PEDOT : PSS) films with both face-on and edge-on orientations exhibit exceptional electronic conductivity and ion diffusion efficiency, with capacitive performance 1.33 times higher than that of PEDOT : PSS films with only edge-on orientation. Consequently, molecular chain orientations conducive to charge transport not only enhance inter-chain coupling, but also effectively reduce ion transport resistance, enabling efficient capacitive energy storage. This research provides novel insights for the design and development of higher performance CPs-based electrode materials., (© 2024 Wiley-VCH GmbH.)

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The pressing concerns of environmental sustainability and growing needs of clean energy have raised the demands of carbon and organic based energy storage materials to a higher level. Redox-active organic-carbon composites electrodes are emerging to be enablers for high-performance, high power and long-lasting energy storage solutions, especially for electrochemical capacitors (EC). This review discusses the electrochemical redox active organic compounds and their composites with various carbonaceous materials focusing on capacitive performance. Starting with the most common conducting polymers, we expand the scope to other emerging redox active molecules, compounds and polymers as well as common carbonaceous substrates in composite electrodes, including graphene, carbon nanotube and activated carbon. We then discuss the first-principles computational studies pertaining to the interactions between the components in the composites. The fabrication methodologies for the composites with thin organic coatings are presented with their merits and shortcomings. The capacitive performances and features of the redox active organiccarbon composite electrodes are then summarized. Finally, we offer some perspectives and future directions to achieve a fundamental understanding and to better design organic-carbon composite electrodes for ECs. [ABSTRACT FROM AUTHOR]

The analysis of structures of multi-station sources for arc welding, designed on the base of capacitive energy storages, was carried out. Their prospects for creation of highly-efficient welding and technological systems are shown. The structures of centralized power supply systems of welding stations are considered, in which one powerful electric energy capacitor is used. A decentralized power supply system is more flexible, when the own electric energy capacitor is installed at each workplace. Its advantage consists in the fact that a standard rectifier of type VDGM can be used. For shipbuilding, a combined power supply system can be used, which implements the positive qualities of both power supply systems and provides a high quality and power efficiency of the welding process. As an example of the use of multi-station power sources, a scheme is given, which is based on the method of charge transfer. 13 Ref., 6 Fig. [ABSTRACT FROM AUTHOR]

Analysis of structures of multistation sources for arc welding, designed on the base of capacitive energy storages, was carried out. Their prospects for creation of high-efficient welding-technological systems are shown. The structures of centralized power supply systems of welding stations are considered, in which one powerful electric energy storage is used. A decentralized power supply system of the stations is more flexible, when an individual electric energy storage is installed at each workplace. Its advantage consists in the fact that a standard rectifier of VDGM type can be applied. For shipbuilding, a combined power supply system can be used, which implements the positive qualities of both power supply systems and provides a high quality and power efficiency of the welding process. As an example of the use of multistation power sources, a diagram is given, which is based on the method of charge transfer. 13 Ref., 6 Figures. [ABSTRACT FROM AUTHOR]

The operational features of the charger of a high-voltage capacitive energy-storage unit based on a transistor serial resonant inverter in a mode of voltage stabilization on the storage unit are considered. With the use of a mathematical model, the causes and domains of the existence of abnormal charger operation modes in the course of output-voltage stabilization accompanied by magnetic-circuit saturation in a high-voltage transformer, transistor current overload, and excess voltage across the elements of the resonant circuit are established. An algorithm for controlling the transistors of the inverter excluding these modes is proposed. [ABSTRACT FROM AUTHOR]

The concept of automatic generation control has an immense role in providing quality power in an interconnected system. To obtain quality power by controlling the oscillations of frequency and tie-line power, a proper controller design is necessary. So, an innovative endeavor has been undertaken to enforce a two-stage controller with the amalgamation of a proportional-derivative with filter (PDN) (integer-order) and a fractional order integral-derivative (FOID), i.e., PDN(FOID). In an effort to acquire the controller’s gains and parameters, a bio-inspired meta-heuristic spotted hyena optimizer is applied. Various examinations manifest the excellence of PDN(FOID) over other controllers such as integral, proportional–integral, proportional–integral-derivative filter, and fractional order PID from perspectives concerning the diminished amount of peak anomaly oscillations, and the instant of settling for a three-area system. The system includes thermal–bio-diesel in area-1; a thermal–geothermal power plant in area-2; and a thermal–split-shaft gas turbine in area-3. It is also observed that the presence of renewable sources such as wave power plants and photovoltaics makes the system significantly better compared to the base system, when assessed individually or both together. Action in a combination of capacitive energy storage with duple compensation is also examined using the PDN(FOID) controller, which provides a noteworthy outcome in dynamic performance. Moreover, PDN(FOID) parameter values at a nominal condition are appropriate for the random patterns of disturbance needed for optimization.

The authors of the study work out to determinate of the mathematical model of supercapacitors as an object of an electric traction system capable of providing non-encumbering of obtaining research results and correct reproduction of energy exchange processes in conditions of repeated-short-term modes of traction load operation. In paper, authors make a comparative assessment of six models for the possibility of their integration into the model of electric traction systems with on-board placement of the energy storage. [ABSTRACT FROM AUTHOR]

Purpose. An experimental verification of the existence of a range of values for the parameters of the capacitive energy storage of the magnetic-pulse installations with controlled vacuum discharger, in which, with a high probability, there is a «cut» of the discharge current pulses and the expansion of cylindrical thin-walled tubular workpieces using an external coil. Methodology. High voltage magnetic-pulse installation of NTU «KhPI» with controlled vacuum discharger, multiturn coil with inside dielectrical die and inside aluminum alloy workpiece are used. The capacitance and charge voltage of capacitive energy storage are changed. Discharge current pulses are measured by Rogowski coil and the oscillograph. Results. Parts of complicated shape are made by expansion of cylindrical tubular workpieces with help of external coil. Pressed metallic tubular part is removable from inner dielectric rod. Originality. The frequency of «cut» pulse is defined by negative magnetic field pressure amplitude. It is shown that we must coordinate this frequency and charge voltage with capacitive storage parameters by high probability of pulse «cut». Practical value. It is shown how to use installations with controlled vacuum dischargers in magnetic forming technology based on «cut» pulses. R [ABSTRACT FROM AUTHOR]

The purpose of the article is to evaluate the efficiency of an induction-type linear pulse electromechanical converter (LPEC) when operating in shock-power mode and excitation from an alternating voltage source (AVS) in comparison with excitation from a capacitive energy storage (CES). A mathematical model of an induction-type LPEC has been developed both when excited by a unipolar pulse from a CES and from an AVS using lumped parameters of the windings, which takes into account the interrelated electromagnetic, mechanical and thermal processes. It has been found that when the LPEC is excited from the AVS with a voltage frequency of 50 Hz, the electrodynamic force takes on a periodic decaying character with a significant prevalence of positive components of forces over negative ones. The maximum value of the force is much less, and the value of its impulse is much greater than in the LPEC, excited from the CES. With an increase in the frequency of the AVS voltage from 50 to 150 Hz, the highest value of the current density of the inductor winding decreases, and in the armature winding it increases. The greatest values of force and impulse of force are realized at a voltage frequency of 150 Hz. With an increase in the AVS frequency, the relative indicator of the efficiency of the LPEC increases. References 15, figures 4. [ABSTRACT FROM AUTHOR]

Polymer thin films operable under concurrent electric and thermal extremes represent critical building blocks of capacitive energy storage and electrical isolator for modern power and electronic systems with ever-increasing demands for power density and payload efficiency. However, polymer dielectrics are prone to fast aging under high fields due to hot electrons injected from electrodes. Especially, performance high-heat polymers such as polyimides with high aromaticity suffer fast aging induced by non-thermalized electrons even at moderate fields due to their intrinsically low bandgap and injection barrier. Herein, a facile, low-cost, and scalable interface-engineering approach utilizing the highly ordered organic/inorganic layered nanocoatings is reported, which serve as a retrofittable solution to break this design constraint. By probing the energetic modes of transport and aging at pre-breakdown field, we demonstrate that our 2D montmorillonite (MMT) self-co-assembly nanocoatings can effectively boost the dielectric properties of substrate polyimide (PI) film by suppressing the charge injection and shifting the fast mode of hot-electron aging to a slow, ultimately thermalized process. This aging-impeding scheme imparts PI films with an exceptional endurance capability (enhanced by 100 MV/m) and a 6 × improved charge-discharge efficiency at an elevated temperature of 175 °C. The nanostructured interface engineering disclosed in this work thus opens a new pathway of boosting the performance of a spectrum of high-heat polymer dielectrics already commercially available in thin gauges of films for applications in zero-emission electric aircraft and renewable energy integration. [Display omitted] • A scalable interface-engineering booster for high-heat polymer films. • Energetic mode of fast aging revealed experimentally for the first time. • 2D nanocoating effective in charge injection suppression and shifting hot-electron aging to slow, thermalized process. • Polyimide films with nanocoating exhibit exceptional endurance (+ 100MV/m) and a 6× charge-discharge efficiency at 175 °C. [ABSTRACT FROM AUTHOR]

The paper reveals the electro-physical features of the formation of multi-channel pulse currents and fast-migrating electric sparks in the layer of current-conductive granules of electric-discharge installations (EDIs) with reservoir capacitors. Such features make it possible to increase many times the productivity of the electric-spark dispersion of metal granules during single discharge current of reservoir capacitors, which flows between the electrodes of EDIs. Theoretical substantiation and experimental confirmation of multi-channel spark discharges in the layer of conductive granules are presented. The influence of the capacitance and charge voltage of reservoir capacitors on the nature of transient processes in the discharge circuit of the EDIs is investigated. The dependence of the effective value of the active load resistance of the EDIs on the value of the pre-charge voltage of its reservoir capacitors and the value of its capacitances has been experimentally determined. It is proved that an increase in the averaged Q-factor of the discharge circuit with an increase in the charge voltage of the capacitor bank of EDI is caused by a decrease in the effective value of the active resistance of the layer of metal granules when spark-generating discharge currents flow through it. References 16, Figures 7.

• Renewable energy source (Photovoltaic) based electronic power supply. • Capacitive energy storage based system. • An electronic structure design for hierarchical order charge and discharge operations. • Isolated structure for safety of critical DC loads. In this study, to the aim was to design an isolated, reliable and efficient DC-DC (flyback based) photovoltaic energy sourced supply unit, which has its own electrolyte-super capacitor based energy storage unit in order to compensate for disruptions and failures that can occur in photovoltaic solar panels. In this storage unit, a hierarchical charging structure has been developed for eliminating the drawbacks of battery technologies such as cooling issues, chemical dangers, heavy weight, charging and discharging current/voltage limitations. The designed supply unit is capable of operating in a wide range of input voltages for the supply of important and expensive solar-based photovoltaic subsystems. Also, it was designed to supply a steady and balanced power to control systems that have microcontrollers or expensive control elements for different purposes up to 50 W. The design can be considered as a model for an uninterruptible power supply with a specific capacitive storage. The designed unit has important advantages due to its large usage area, especially microgrid and off-grid systems, its low cost and less complex construction. The designed hierarchical charging super capacitor based energy storage unit in this study is expected to have important implications for future research due to its possibility to be developed in accordance with different environmental conditions and objectives. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride nanosheets (BNNSs) are two-dimensional nanomaterials with graphitic-like layered nanostructures, high surface areas, and large aspect ratios. Owing to their excellent thermal conductivity, electrical and mechanical strengths, BNNSs are emerging as multifunctional fillers in polymer dielectrics. In this article, the authors review the recent progress in the BN-containing polymer nanocomposites designed for high-performance film capacitors. While general synthetic approaches to BNNSs and polymer/BNNS nanocomposites are summarized, particular attention is placed on structure-property correlation and rational structural design of the composites with optimized dielectric properties and capacitive performances. In stark contrast to the polymer composites employing high dielectric constant fillers to enhance the electric displacement, a new design concept based on the utilization of BNNSs with a wide bandgap to impede electrical conduction and consequently improve breakdown strength and charge-discharge efficiency of the polymer composites, is highlighted. The significance of developing dielectric capacitors with desirable thermal conductivity and thermal stability to ensure their robust and efficient operation is emphasized. The merits and challenges regarding the existing polymer dielectrics containing BNNSs for energy storage are identified. An outlook for future research opportunities and engineering applications is also presented in this review.

Purpose. The goal of the paper is to investigate the influence of the power circuits of the linear pulse-induction electromechanical converters (LPIEC), which form the current pulse of excitation of the inductor from the capacitive energy storage (CES), to its electromechanical parameters. Methodology. A circuit mathematical model of LPIEC was developed, on the basis of which recurrence relations were obtained for calculating the interrelated electromagnetic, mechanical, and thermal parameters of the LPIEC. This model makes it possible to calculate the LPIEC parameters for various power circuits, the inductor of which is excited by the CES. Results. It is established that electromechanical LPEC parameters with power circuit forming an aperiodic current excitation pulse of an inductor are better than in LPIEC with excitation of an inductor by an unipolar current pulse, but worse than in LPIEC with excitation of an inductor by a vibrationally damped current pulse. In this converter, during operation, the inductor is heated most, and the armature is heated least. It is established that in LPIEC with power circuit that forms an aperiodic current pulse of excitation of an inductor with the connection of an additional CES, all electromechanical parameters are higher in comparison with the LPIEC with a power circuit that forms a vibrationally damped current excitation pulse of the inductor. However, in this LPIEC the excess of the temperatures of the active elements increases, especially strongly in the inductor, and the efficiency of the converter decreases. Originality. For the first time, the LPIEC has been investigated using the power circuit that forms an aperiodic current pulse of excitation of an inductor with the connection of an additional CES. It is established that in this LPIEC all electromechanical parameters are higher than for LPIEC with power circuits forming an unipolar or oscillating-damped current excitation pulse of the inductor. Practical value. In the LPIEC with power circuit that forms an aperiodic current pulse of excitation of the inductor with the connection of an additional CES, the electromechanical LPIEC parameters increase. This increases the temperature rise of the inductor, and the temperature rise of the armature decreases. The effectiveness of this LPIEC is also reduced.

This article presents a wireless power transfer topology based on inductive power transfer (IPT) with integrated supercapacitor (SC) energy storage. The proposed topology is suitable for dynamic charging of electric vehicles (EVs), where pulses of energy must be processed without placing excessive strain on the utility grid or the EV battery. This topology extends the functionality of a typical LCL-tuned bidirectional IPT system by adding the ability to store energy in an SC in a controlled manner. Operation of the system is described in terms of the switching patterns and control variables required to transfer energy between the input, output, and the SCs. A mathematical model that predicts the overall transfer of power between the input, output, and SCs is presented along with experimental results at a nominal power level of 3.8 kW to validate the model and the topology under a variety of typical operating conditions. [ABSTRACT FROM AUTHOR]

Capacitive energy storage has advantages of high power density, long lifespan, and good safety, but is restricted by low energy density. Inspired by the charge storage mechanism of batteries, a spatial charge density (SCD) maximization strategy is developed to compensate this shortage by densely and neatly packing ionic charges in capacitive materials. A record high SCD (ca. 550 C cm−3) was achieved by balancing the valance and size of charge‐carrier ions and matching the ion sizes with the pore structure of electrode materials, nearly five times higher than those of conventional ones (ca. 120 C cm−3). The maximization of SCD was confirmed by Monte Carlo calculations, molecular dynamics simulations, and in situ electrochemical Raman spectroscopy. A full‐cell supercapacitor was further constructed; it delivers an ultrahigh energy density of 165 Wh L−1 at a power density of 150 WL−1 and retains 120 Wh L−1 even at 36 kW L−1, opening a pathway towards high‐energy‐density capacitive energy storage. [ABSTRACT FROM AUTHOR]

Much research is being done towards developing innovative materials and devices for energy production and storage. In this study, a less expensive and eco-friendly polymer nanocomposite (PNC), in combination with polyvinyl alcohol (PVA) and KCl/Carbon black (CB), at different weight percent was prepared and embedded between multi-walled carbon nanotube (MWCNT) electrodes for fabricating an all-solid-state supercapacitor (SC) device. Modification in electrode preparation and addition of KCl and CB to PVA/H3PO4 polymer electrolyte enhanced the ionic conductivity and initiated additional pseudo-reaction at electrode–electrolyte interface. Results showed that the SC with PVA/0.75 wt%KCl/0.3 wt%CB nanodielectric membrane has the highest energy storage capability for 0–1 V and reached a maximum energy density of 14.16 Wh/kg (at 1Ag−1) and power density of 1.38 KW/kg (at 5Ag−1). The PNC membrane showed excellent mechanical stability (up to 45 MPa under tensile loading). In addition, capacitance retention of 91.16% over 3000 cycles and an enhanced self-discharge of 60.63% were observed after 1000 min. The reliability of the same membrane was compared with commercially buyable Nafion®112 membrane. [ABSTRACT FROM AUTHOR]

Hydrogenated diamond-like carbon and aluminum oxide thin films were used in combination to fabricate capacitors in order to investigate the effect of multiple dielectrics on dielectric constant, breakdown strength, and energy density. It was found that capacitors made by combining the two materials exhibited significantly higher breakdown strength and energy density than capacitors made with either dielectric material alone. In addition, the model for calculating the combined dielectric constant for multiple dielectrics was validated. The highest energy density (U e = 5.2 J/cm3) capacitor made for this investigation had a breakdown strength of 5.3 MV/cm and an effective dielectric constant of 5.3. [ABSTRACT FROM AUTHOR]

This article discusses a Whale Optimization (WO) controller for design analysis, stability management, application, and performance analysis of a deregulated two-area multi-source energy system. Within the power grid, the Automatic Generation Control (AGC) maintains the power balance and strengthens the sudden frequency disturbance of the grid. Various researchers are targeted many kinds of fast-acting energy-storing devices to dampen space frequency oscillations and diversion of the tie line because of unexpected load variation. To regulate the power flow between multi-areas, load frequency control (LFC) is used by keeping frequency constant. But, to design a controller for minimizing the issues of LFC remains a challenge within the deregulated atmosphere. The main objective of the proposed methodology is to design a controller for minimizing the issues in LFC within the deregulated atmosphere. A two-area deregulated hydrothermal power system is employed to analyze many LFC problems in the deregulated power grid. During this modeling, the Thyristor-Controlled Phase Shifters (TCPS) and Capacitive Energy Storage unit (CES) are placed in the tie line and its control space. To mitigate the various issues of LFC in a two-area deregulated hydrothermal power system, the CES–TCPS combination is placed between the two control areas and the transient performance of constant is evaluated. The WO controller will increase the system power size to focus on the better performance of low-frequency management tasks. In addition, the effectiveness of the WO algorithm in tuning the proportional integral controller is also compared in a different contract (unilateral, bilateral and contract violation cases) scenarios of the proposed deregulated power system. Finally, the simulation is carried out in MATLAB/Simulink platform and the results obtained for the WO controller is compared with the normal and fuzzy PI controllers. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stepwise-design strategy was proposed to tailor energy storage performance. • High W rec (∼6.84 J/cm3), դ (∼81.5 %), and E b (∼712 kV/cm) were gained. • Remarkable thermal/frequency/cycling stabilities are realized. • The origin is explored by ex/ in situ multiscale structure characterizations. Although comparable energy storage performance (ESP) has been realized in NaNbO 3 (NN)-based antiferroelectric (AFE) ceramics, how to simultaneously realize large energy density (W rec), large storage efficiency (η), and outstanding thermal stability still remains a remarkable challenge. Herein, by progressively substituting BiFeO 3 (BF) and CaTiO 3 (CT), we propose a stepwise-design strategy to activate comprehensive exceptional ESP in NN-based relaxor AFE ceramics. The substitution of BF with high spontaneous polarization and CT with high breakdown strength (E b) into NN generates stabilized AFE R phase, strong tilt distortions of oxygen octahedron, ultrasmall and highly dynamic polar nanoregions, and refined grains, thus manifesting enhanced high-field polarizability, significantly delayed polarization saturation, and ultrahigh E b macroscopically. With the deliberate stepwise-design route, we realize an optimal overall ESP in 0.6(0.96NN-0.04BF)-0.4CT relaxor AFE ceramics, featuring a high W rec of 6.84 J/cm3, a large η of 81.5 %, along with super temperature/frequency/fatigue stabilities, which shows great performance merits compared with previous reports. This work demonstrates that stepwise-design engineering approach by manipulating the crucial structures exerts a positive size effect on the polarization and breakdown response of dielectrics, and can be exploited for designing more high-performance energy storage ceramics. [ABSTRACT FROM AUTHOR]

The purpose of the article is to evaluate the efficiency of an induction-type linear pulse electromechanical converter (LPEC) when operating in shock-power mode and excitation from an alternating voltage source (AVS) in comparison with excitation from a capacitive energy storage (CES). A mathematical model of an induction-type LPEC has been developed both when excited by a unipolar pulse from a CES and from an AVS using lumped parameters of the windings, which takes into account the interrelated electromagnetic, mechanical and thermal processes. It has been found that when the LPEC is excited from the AVS with a voltage frequency of 50 Hz, the electrodynamic force takes on a periodic decaying character with a significant prevalence of positive components of forces over negative ones. The maximum value of the force is much less, and the value of its impulse is much greater than in the LPEC, excited from the CES. With an increase in the frequency of the AVS voltage from 50 to 150 Hz, the highest value of the current density of the inductor winding decreases, and in the armature winding it increases. The greatest values of force and impulse of force are realized at a voltage frequency of 150 Hz. With an increase in the AVS frequency, the relative indicator of the efficiency of the LPEC increases. References 15, figures 4.

Summary: During major disturbances in electric power system (PS) penetrated with renewable energy sources, primary and supplementary automatic generation control (AGC) strategies usually show inefficiency in mitigating the frequency and power oscillations because of sluggish control action. The frequency and power deviations should be controlled to retain the generation‐demand balance, which reinforce the quality and stability of overall PS. The fast‐acting energy storage systems (ESSs) having very small time constants like capacitive energy storage (CES) and redox flow battery (RFB) are utilised in this study to improve these dynamic responses. To conduct the analysis, initially, a two‐area nonreheat thermal PS with extra generations from wind turbine system (WTS) and dish‐stirling solar thermal system (DSTS) is explored extensively, and then to validate the efficacy of the method, the approach is tested on two‐area nonreheat thermal system having governor deadband (GDB) nonlinearity, reheat thermal, and restructured multisource thermal gas systems. An imperialist competition algorithm (ICA) optimised fuzzy PID‐filter‐(1 + PI) controller named as FPIDF‐(1 + PI) is utilised as supplementary controller, and its performance with CES/CES‐RFB is compared with ICA‐optimised FPIDF with/without CES and existing optimal PI/PID/PIDF/FPID controller without CES. Investigation of dynamic responses for sudden variation in power demand unveils the superiority of the control approach compared with others regarding settling time, peak undershoot, and performance index. Analysing the impact of ESSs on the responses divulges that the amalgamation of CES‐RFB in PS imparts better system dynamics. The robustness analysis suggests that ICA‐optimised controller with ESSs performs excellently and robustly for ±25% variation in PS parameters, random load disturbances, and nonlinearities. [ABSTRACT FROM AUTHOR]

Constant-current charging is the optimal solution for charging linear (fixed) capacitors. In this letter, we extend this principle to nonlinear capacitors using a variational method. We address the case where the capacitance depends only on the applied voltage. We show that a nonlinear capacitor stores energy electrostatically and by another mean, depending on the phenomena behind the variation of the capacitance. We compute the optimal charging voltage curves for a linearly increasing or decreasing capacitance with the bias voltage. We highlight that the efficiency of the charging is improved if the capacitance increases with the applied voltage, and vice versa. We finally apply our results to two types of nonlinear capacitors that are widely used in power electronics: Supercapacitors and class II ceramic capacitors. We demonstrate that the charging efficiency is higher for supercapacitors than for ceramic capacitors. [ABSTRACT FROM AUTHOR]