Capacitive Energy Storage Devices Research Articles

Superb energy density in biomass-based nanocomposites with ultralow loadings of nanofillers

Biomass dielectric polymers hold promise in developing renewable and biodegradable capacitive energy storage devices. However, their typical discharged energy density remains relatively low (<20 J/cm3) compared to other existing synthetic polymers derived from petroleum sources. Here a greatly enhanced discharged energy density is reported in diluted cyanoethyl cellulose (CEC) nanocomposites with inclusion of ultralow loadings (0.3%, in volume) of 30-nm-sized TiO2 nanoparticles. Owing to the interfacial polarization introduced by interface, the composite of 0.3% exhibits a large dielectric constant of 29.2 at 1 kHz, which can be described by interphase dielectric model. Meanwhile, the introduction of nanofillers facilitate the formation of deeper traps impeding electrical conduction in CEC, which results in an ultrahigh breakdown strength of 732 MV/m. As a result, a remarkable discharged energy density of 12.7 J/cm3 with a charge-discharge efficiency above 90% is achieved, exceeding current ferroelectric-based and biomass-based nanocomposites. Our work opens a novel route for scalable biomass-based dielectrics with high energy storage properties.

Tuning Dielectric Properties with Nanofiller Dimensionality in Polymer Nanocomposites.

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.

Research of the Primary Electric Energy Storage System of a Traction Photovoltaic Module

Purpose. The main idea of the work is that the electric energy generated by photovoltaic installations is supplied in small parts to capacitive energy storage devices of low power, and then these «portions» of energy are supplied to one common, so-called traction storage device. The research is aimed at obtaining time diagrams of current and voltage changes in the proposed system. Methodology. A review of the world literature on the topic of work was conducted. The basis of this research is the analysis of transient processes in the electrical circuits of the system during the transfer of energy from the photovoltaic module to the traction capacitor under the influence of various control signals: series, parallel, combined. The main research method is computer simulation. The Scilab software environment was used to simulate the operation of the electric energy storage system. Findings. The relevance of the research and development of a primary electric energy storage system using a traction photovoltaic module has been proved. The key mathematical dependencies between the parameters of the constituent elements of electrical circuits are established. The structure of a site with electric energy storage with traction photovoltaic modules and a converter-pulse signal unit is proposed. The graphical characteristics of transient processes that occurred during the transfer of energy from low-power capacitive elements to a high-power capacitive element (traction capacitor) were obtained. Originality. For the first time, graphical dependences of energy transfer between system elements were obtained, which allows for a reasonable choice of the parameters of these elements. Also, for the first time, time dependencies describing the law of control of the process of energy transfer between system links were obtained, which will allow determining the rational modes of its operation. Practical value. The results of the research open up new opportunities in the research field in the development of large-scale experimental models of the maglev path structure in the case of the introduction of a system of distributed primary energy storage in a traction photovoltaic module.

PVA/CMC/PEG blended polymer loaded with ZnCo1.9Al0.1O4/carbon nanoparticles/PANi as a promising films for UV radiation shielding

Polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) have been employed as polymeric matrices for the synthesis of polymeric nanocomposite films that incorporate ZnCo1.9Al0.1O4, carbon nanoparticles (CNPs) and polyaniline (PANI) as fillers. X-ray diffraction technique was utilized to examine the structure of ZnCo1.9Al0.1O4 filler and the formed PVA/CMC/PEG/ZnCo1.9Al0.1O4/CNPs/x wt % PANi blends. The morphology of the doped blend was explored using the scanning electron microscopy technique. The increases in absorbance, especially in the UV spectrum, demonstrate the potential of these blends in UV-blocking and UV-filtering applications. The minimum direct and direct optical energy gaps are 5.62 and 4.77 eV obtained as the quantity of PANi became 0.3 wt %. The highest refractive index values (n = 1.66 at 600 nm) were acquired as the blend was doped with 0.4 wt % PANi. The impact of different fillers on the linear and nonlinear optical parameters was explored. The inclusion of ZnCo1.9Al0.1O4/CNPs/x wt % PANi resulted in an improvement in PVA/CMC/PEG blended polymer's optical conductivity. The FL intensities of the loaded blends are comparatively lower than those of the undoped blend. The values of the dielectric constants of doped blends with x = 0 or 0.4 are notably higher than those of other blends. Doped blend with x = 0.2 exhibited the highest energy density value (9 × 10−3 J/m3 at 1 kHz). The doped blend with x = 0.4 has the highest ac conductivity (1.53 × 10−8 Sm−1 at 1 kHz). The influence of doping on the relaxation time and capacitance behavior of the host blend was inspected. These outcomes suggest the opportunity of employing the created nanocomposites in capacitive energy storage and optoelectronic devices.

Ferroelectric and Relaxor-Ferroelectric Phases Coexisting Boosts Energy Storage Performance in (Bi0.5Na0.5)TiO3-Based Ceramics.

With the intensification of the energy crisis, it is urgent to vigorously develop new environment-friendly energy storage materials. In this work, coexisting ferroelectric and relaxor-ferroelectric phases at a nanoscale were constructed in Sr(Zn1/3Nb2/3)O3 (SZN)-modified (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT) ceramics, simultaneously contributing to large polarization and breakdown electric field and giving rise to a superior energy storage performance. Herein, a high recoverable energy density (Wrec) of 5.0 J/cm3 with a conversion efficiency of 82% at 370 kV/cm, a practical discharged energy density (Wd) of 1.74 J/cm3 at 230 kV/cm, a large power density (PD) of 157.84 MW/cm3, and an ultrafast discharge speed (t0.9) of 40 ns were achieved in the 0.85BNBT-0.15SZN ceramics characterized by the coexistence of a rhombohedral-tetragonal phase (ferroelectric state) and a pseudo-cubic phase (relaxor-ferroelectric state). Furthermore, the 0.85BNBT-0.15SZN ceramics also exhibited excellent temperature stability (25-120 °C) and cycling stability (104 cycles) of their energy storage properties. These results demonstrate the great application potential of 0.85BNBT-0.15SZN ceramics in capacitive pulse energy storage devices.

Enhancing the performance of PVC/PMMA polymer blend through hybrid nanofiller of TiO2 NPs/GNPs for capacitive energy storage applications

Polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) have been used as polymeric matrices for the synthesis of polymeric nanocomposite films that incorporate titanium oxide nanoparticles (TiO2 NPs) and graphite nanoplatelets (GNPs) as nanofillers. Based on TEM studies, TiO2 nanoparticles have a tetragonal anatase phase, ranging in size from 15 to 60 nm, whereas GNPs have a nanoplatelet-like shape, varying in thickness from 10 to 20 nm. XRD analysis shows that PVC/PMMA polymer nanocomposite samples have less crystallinity when added with TiO2 NPs and GNPs. Infrared Fourier analysis (FT-IR) indicated a complex interaction between the PVC/PMMA blend and both GNPs and TiO2 NPs. The UV/visible spectrum of the PVC/PMMA blend showed two absorbance peaks at 279 and 223 nm which may result from the n→π* and π→π* transitions. Moreover, optical bandgaps were reduced for both indirect and direct transitions when TiO2 NPs and GNPs were added. AC electrical conductivity and dielectric properties of the samples were measured at room temperature. Results indicated a significant increase in conductivity after filling from 2.6 x 10−14 S/cm for pure PVC/PMMA to 7.3 x 10−6 S/cm for PVC/PMMA-TiO2/GNPs nanocomposite. In addition, high nanoparticle concentrations lead to higher composite dielectric loss and dielectric constants. These findings suggest the possibility of using the prepared nanocomposites in capacitive energy storage and optoelectronic devices.

PVDF/PI/BT nanocomposites with excellent charge/discharge efficiency obtained by inserting linear polymer to adjust the ferroelectricity

The problem of low charge/discharge efficiency of ceramic/polymer composites is still one of the hot topics in current research on dielectric materials. Here, we demonstrate that the ferroelectric property of ceramic/PVDF-based composites can be modulated by the introduction of linear polymer PI and the use of a spin-coating process. PI inhibits some polarization and partial dipole orientation by interacting with the molecular chains of the amorphous phase of PVDF and BT nanoparticles. As a result, the decrease in crystallinity and loss led to improved dielectric properties and charge/discharge efficiency. The findings demonstrate that the microstructure of PVDF-PI/BT nanocomposite is uniform and dense, with outstanding dielectric characteristics and high charge/discharge efficiency. The permittivities were stabilized in the range of 12.87–17.86 at 100 Hz, and the dielectric losses were all less than 0.27. Compared with the previously reported binary ceramic/polymer composites, the PVDF-PI/BT nanocomposites possessed a high charge/discharge efficiency with a small variation (63%-84%). This work offers an easy and efficient scheme to obtain nanocomposites with outstanding dielectric characteristics and charge/discharge efficiency. It may be a potential candidate for flexible dielectric substrates for advanced flexible capacitive energy storage devices.

Development of method for frequency regulation of output current in high-voltage transformerless resonant chargers of capacitive energy storage devices

The object of research is high-voltage systems of electric discharge installations for various technological purposes. The work reports solving the problem of enabling the rate of charging of a capacitive energy storage, set by the requirements of a certain high-voltage technology. The quantitative characteristics of the deviation of the output current of the resonant inverter from the set stabilized value when changing the switching frequency of inverter switches in the range of output voltage change from 0 to 20 kV were determined. Using the Fourier transform of the rectangular input voltage, the frequency regulation possibility of the output current of the charger for capacitive energy storage devices was analyzed. Estimation dependences of the output current of resonant inverter on the load resistance and frequency deviation from resonant frequency were derived. These dependences could be used to implement frequency control over the switching inverter transistors, with the help of which the given effective value of the output current of the resonant inverter is obtained. A method of frequency regulation of the output current in high-voltage transformerless resonant charging devices of capacitive energy storage devices has been developed. Special feature of this method is that it is based on the frequency dependence of reactive resistances of the inductance and capacitance of the resonant circuit connected in series. Owing to that, it makes it possible to adjust the switching frequency of the inverter’s power switches depending on the relative resistance of the load and the specified growth rate of the capacitive energy storage voltage. The results reported here could be used in the design of benches for testing the electrical strength of high-voltage cables, as well as for the construction of high-voltage transformerless chargers in systems of electric discharge impulse processing of materials

Electromechanical and thermophysical processes in the pulse induction accelerator of plasma formation

Introduction. Work on the creation and throwing of plasma formations is carried out in the world's leading scientific centers in various ways. The creation of a plasma formation with duration of several milliseconds and its acceleration in an open atmospheric environment to a distance of 0.5-0.6 m was achieved. To create plasma, the energy of the primary discharge circuit is used, followed by the acceleration of the gas-plasma formation with the help of the energy of the secondary circuit. Plasma formation is also obtained due to the electric explosion of a conductor in a rapidly decreasing strong magnetic field, etc. The purpose of the article is a theoretical and experimental study of electromechanical and thermophysical processes in a pulsed induction accelerator, which ensures the creation of plasma formation due to thermal ionization as a result of the electric explosion of the conductor and its throwing in the atmospheric environment relative to the inductor. Method. For the analysis of electromechanical and thermophysical processes in the pulse induction accelerator of plasma formation (IIPP), a mathematical model of the accelerator was developed and implemented in the Сomsol Multiphysics software package, in which the anchor does not change its shape and aggregate state during operation and takes into account the parameters of the accelerator distributed in space. Results. Calculated electromechanical and thermal characteristics of the accelerator. It is shown that the temperature rise in the aluminum foil anchor is significantly uneven. The maximum temperature value occurs in the middle part of the foil closer to the outer edge, and this temperature is significantly higher than the boiling point of aluminum. Scientific novelty. Experimental studies of the IIPP were carried out, in which the armature is made of aluminum and copper foil, and the inductor connected to the high-voltage capacitive energy storage device is made in the form of a flat disk spiral. It was established that during the operation of the IIPP, the armature goes into a plasma state and moves vertically upwards, turning into a three-dimensional lump or a pile of small particles that rose to a considerable height relative to the inductor. Experimentally, the characteristic circular circuit of thermal heating of the copper foil of the anchor, which is fixed on a glass-textolite sheet, is shown, which indicates a similar nature of plasma formation. Practical value. The results of experimental studies with an accuracy of up to 15 % coincide with the calculated ones and show the validity of the IIPP concept, in which, due to the high density of the induced current in the armature, thermal ionization occurs as a result of an electric explosion of the conductor with its transition to the plasma state. And the interaction of the plasma formation with the magnetic field of the inductor leads to the appearance of an electrodynamic force that ensures its movement in the open atmospheric environment.

Tikhonov regularization for the deconvolution of capacitance from the voltage–charge response of electrochemical capacitors

The capacitance of capacitive energy storage devices cannot be directly measured, but can be estimated from the applied input and measured output signals expressed in the time or frequency domains. Here the time-domain voltage–charge relationship of non-ideal electrochemical capacitors is treated as an ill-conditioned convolution integral equation where the unknown capacitance kernel function is to be found. This comes from assuming a priori that in the frequency domain the charge is equal to the product of capacitance by voltage, which is in line with the definition of electrical impedance. The computation of a stable solution to this problem particularly when dealing with experimental data is highly sensitive to noise as it may lead to an oscillating result even in the presence of small errors in the measurements. In this work, the problem is treated using Tikhonov’s regularization method, where a degree of damping is added to each singular value decomposition (SVD) component of the solution, thus effectively filtering out the components corresponding to the small singular values. The regularized time-domain capacitance of a commercial electric double-layer capacitor is found to be in good agreement with the frequency-to-time transformed capacitance obtained from impedance spectroscopy.

Leader Harris Hawks algorithm based optimal controller for automatic generation control in PV-hydro-wind integrated power network

• A novel attempt has been put together to design a Model Predictive Control based on the leader Harris Hawks Optimization approach for a PV integrated LFC system. Further, a combined AVR-LFC loop has been designed for a PV, wind and hydro integrated hybrid power system. • The validation of the controller's better performance has been obtained through a thorough comparative analysis where the transient response attributes from the proposed controller have been compared with the exiting controllers available in the literature. Also, the convergence mobility of the proposed LHHO optimizer has been compared with HHO, WOA, and PSO algorithms. • To further strengthen the frequency stability of the network, the authors have proposed and implemented the virtual inertia and capacitive energy storage devices in association with the LHHO-MPC controller. • The robust nature of the proposed controller algorithm has been assessed under different test case scenarios where the step load perturbation (SLP) values have been varied randomly, and the stochastic load model has been considered. Also, various nonlinearities and reduced inertia cases have been presented to show the efficiency of the proposed LHHO-MPC controller working in coordination with CES and VI units. The work in this manuscript aims at designing a novel control strategy based on the Model Predictive Controller aided with Leader Harris Hawks Optimization (MPC-LHHO) algorithm for the regulation of frequency and voltage in renewable penetrated power systems. Herein, two cases have been considered where the first case discusses the frequency stabilization in a thermal power system linked with the solar photovoltaic (PV) plant. Subsequently, the second case features the simultaneous voltage and frequency regulation in a hybrid interconnected power system including thermal, wind, diesel, photovoltaic, and hydro generation units. Additionally, for both cases, the proposed MPC-LHHO algorithm has been evaluated in coordination with the capacitive energy storage and virtual inertia units. Furthermore, the stability analysis of the controlled PV-thermal system has been conducted using eigenvalues and pole-zero plots. In both cases, the effectiveness of the proposed algorithm has been tested after considering diverse scenarios including random loading, nonlinearities, time delays, reduced inertia and stochastic variations in load. For all these cases the presented algorithm has given a stable response and has ensured proper regulation of voltage and frequency in the renewable integrated power system network.

COMPARATIVE ANALYSIS OF APPROACHES TO DETERMINING THE PARAMETERS OF A CAPACITIVE ENERGY STORAGE FOR ELECTRIC ROLLING STOCK

The article deals with the main existing approaches to determining the parameters of on-board capacitive energy storages for electric rolling stock and their comparative analysis. The advantages and disadvantages of each of the ten considered approaches are set out. Each of the approaches is described and their comparative analysis is performed according to such criteria as the level of research complexity, the financial component of research, the possibility of taking into account the real operation conditions of electric rolling stock while carrying out the research, the method of evaluating the parameters of the on-board capacitive energy storage, the possibility of determining rational parameters, the universality of the approach, considering the technical and economic component and limitations on weight and size of indicators. The power and energy capacity of on-board capacitive energy storage devices, their weight-size indicators when applying each of the considered approaches for the same given operating conditions of the electric rolling stock are determined. A five-car articulated vehicle with an asynchronous traction drive and recovery systems, consisting of metro cars of models 81-7080, 81-7081, 81-7081-01, was chosen as the electric rolling stock. The experimental section between the final stations of the SviatoshynskBrovary line of the utility company “Kyivskyi Metropolitan” was chosen as the specified operating conditions. The payback period and the impact of storage systems with the selected parameters on the performance indicators of the given electric rolling stock while using various approaches are determined. It was found that the most developed approaches, the key point of which is the selection of rational parameters using theoretical research with the help of application-specific software and multi-criteria evaluation methods. The feasibility of using a multi-criteria approach, which allows choosing rational parameters of the capacitive energy storage for electric rolling stock based on three important evaluation criteria, i.e., weight, volume and payback period, is demonstrated. It was established that it is rational to use an on-board capacitive energy storage device of low power and energy intensity.

Thermal Stability of Sputtered Tungsten Nitrides for Solar Thermal Applications

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.

SELF-STARTING OF SYNCHRONOUS MOTORS WITH COMPENSATION INERTION OF THE EXCITATION CONTOUR

The actual scientific problem is solved in the work, which consists in the development, theoretical and experimental researches of devices for self - starting of synchronous motors with compensation of inertia of excitation circuit. The aim of the work is to increase the reliability of the self-starting mode of synchronous motors of responsible mechanisms to maintain the continuity of complex technological processes. In the event of natural disasters and natural disasters, power outages can cause long-term disruptions of technological processes, large material losses, and in some cases fires and explosions, which can lead to human casualties and significant economic damage.&#x0D; Under these conditions, the mode of restarting synchronous motors must be used to power the responsible electric drives of mechanisms, such as mine fans, water pumping stations.&#x0D; To limit the dynamic loads, it is necessary to have the smallest possible value of e.r.s. stator SD in order to limit the switching current, which can be achieved by using various methods and means of extinguishing the field, increasing the time of introduction of automatic re-inclusion or automatic inclusion of the reserve. The calculated dependences of the self-starting modes of SD when extinguishing the magnetic field due to the inclusion of capacitive energy storage devices are obtained. The developed device for self-starting of SD with a capacity of 1000 kW of the drive unit of the pump unit with ENE was implemented at the pumping station of the Dnieper Metallurgical Plant. The efficiency of the developed device does not depend on the presence of voltage that supplies the excitation system in the self-starting mode. The use of ENE in the excitation circuit provides compensation for the inertia of the OZ and increase the input coin and intensive quenching of the magnetic field. The developed devices provide reliable self-starting of synchronous electric drives of mechanisms with continuous technological processes regardless of the presence of voltage in the power supply system of the exciter.

FIELD DISTORTION ARRESTERS WITH IMPROVED TIME LIMITS FEATURES AND INCREASED RELIABILITY

The article considers the features of the design of four-channel rail arresters with field distortion with improved time characteristics and presents the results of studies of their time characteristics. The need for these studies is associated with the widespread use of such dischargers in capacitive energy storage devices that serve as power sources for electrodynamic mass accelerators. At the present stage of the development of science and technology, the use of such accelerators is the most promising for creating experimental stands for modeling in laboratory conditions the processes of high-speed interaction of structural elements of aircraft with particles of different masses and different origins. According to the operating conditions of the experimental stands, in a wide range of changes in both particle masses and interaction velocities, the amplitude values of currents through the low-inductive load of the mass accelerator can vary from kiloamperes to several megamperes at acceleration times from units to hundreds of microseconds. With this in mind, capacitive energy storage devices are performed in a multi-module design. Each module of a capacitive energy storage device is switched to the load by its own switch. To expand the range of operation of the spark gap of the storage device, to obtain the time characteristics of the spark gap with small delay times, to exclude the probability of spontaneous operation of the spark gap, and to provide the stability of the discharge formation during parallel operation of the switches, the designs of four-channel rail spark gaps with field distortion with improved characteristics were developed, their experimental and theoretical studies were carried out.&#x0D; &#x0D; The results of the conducted studies show that the smallest value of the delay time and, accordingly, the spread of the delay time are obtained for a spark gap with field distortion with two control electrodes.&#x0D; &#x0D; It is shown that the obtained analytical expressions presented in the article and the empirical expression calculated for a spark gap with a field distortion with two control electrodes make it possible to determine the values of threshold voltages and delay times, taking into account the statistical delay time and the time of discharge formation.&#x0D; &#x0D; The value of the threshold voltage is determined, at which the process of direct transformation of the streamer into a spark discharge with high conductivity followed by a breakdown of the interelectrode gap is observed.&#x0D; &#x0D; The dependences of the static voltage on the pressure in the inner chamber of the spark gap with field distortion with improved time characteristics are given. It is shown that at a certain distance between the main electrodes at a pressure of 0,3-0,5 MPa, the arresters operate with a margin of electrical strength when the static breakdown voltage is 1,5-2 times higher than the operating voltage applied to the electrodes of the gas gap of the arrestor. This eliminates the possibility of spontaneous triggering of the dischargers of the capacitive energy storage.

Room temperature boronized and phosphated cobalt-nickel metal-organic framework as the electrode material for supercapacitors

Phosphating is a common method for improving the carrier concentration and electrochemical activity of metallic compounds for energy storage applications. However, the traditional phosphating approach often requires high-temperature thermal treatments that accompany complex recrystallization processes, which are not suitable for supercapacitors. Herein, we conducted the boronation of a cobalt‑nickel metal-organic framework (MOF) at room temperature (25 °C) followed by phosphating to fully activate the metallic species of the MOF through crystal structure regulation. The resultant sample (Co-Ni-B-P) achieved excellent electrochemical properties. And the prepared Co-Ni-B-P exhibited a high specific capacitance of 1578 Fg−1 at 1 Ag−1. Meanwhile, an asymmetric supercapacitor (ACS) with activated carbon and the Co-Ni-B-P composite acting as cathode and anode, respectively, delivered a specific energy of 76.5 Wh kg−1 at a specific power of 849 W kg−1. In addition, it exhibited an outstanding cycling stability characteristic of 87% after 5000 charge/discharge cycles. This study provides an ingenious phosphating route for boronation samples to enhance performance of the electrode materials of supercapacitors. This two-step activation approach elucidates the modulation of the electronic structure while maintaining the stacked structure of clearly defined nanosheets, which is promising for the design of MOFs derivatives for capacitive energy storage devices.

МОДЕЛИРОВАНИЕ ПРОЦЕССОВ И МЕТРОЛОГИЯ В ЭЛЕКТРОИМПУЛЬСНЫХ СИСТЕМАХ

Electromagnetic force pulses are forces of mutual repulsion between the inductor and the anchor. Under their action, the anchor is shifted towards the cleaned surface of the affected object and elastic vibrations are transmitted to it. In electro-pulse interaction systems, the duration of the energy accumulation process, and then its release in extremely small time intervals, allows to obtain the maximum possible values of mechanical impulse action on the surface of the affected object. The maximum operating voltage on a capacitive energy storage device can reach 5 kV or higher. Electro-pulse interaction systems are shock-type devices. Compared with other devices of similar purpose (vibrators, electromagnetic or pneumatic shock mechanisms), they have no competition in terms of cleaning efficiency.

Optimized Fractional Order Integral-Tilt Derivative Controller for Frequency Regulation of Interconnected Diverse Renewable Energy Resources

The interconnection of renewable energy systems, which are complex nonlinear systems, often results in power fluctuations in the interconnection line and high system frequency due to insufficient damping in extreme and dynamic loading situations. To solve this problem, load frequency control ensures nominal operating frequency and orderly fluctuation of grid interconnection power by delivering high-quality electric power to energy consumers through efficient and intelligent control systems. To introduce the frequency control of power systems, this paper presents a novel control technique of Fractional Order Integral-Tilt Derivative with Filter (FOI-TDN) controller optimized by the current soft computing technique of hybrid Sine-Cosine algorithm with Fitness Dependent Optimizer (hSC-FDO). For more realistic analysis, practical constraints with nonlinear features, such as controller dead band, communication time delay, boiler dynamics, and generation rate constraint are embedded in the given system model. The proposed approach outperforms some recently developed heuristic approaches such as fitness dependent optimizer, firefly algorithm, and particle swarm optimization for the interconnected power system of two areas with multiple generating units in terms of minimum undershoot, overshoot, and settling time. To improve the system performance, capacitive energy storage devices are used in each area and thyristor control phase shifter is used in the interconnection line of the power system. The potential of the hSC-FDO-based FOI-TDN is demonstrated by comparing it with conventional FOTID/FOPID/PID controllers for two areas with multiple power generators IPS. Finally, a robustness analysis is performed to determine the robustness of the presented control system by varying the system loads and system parameters.

Плазмодинамический синтез оксидов металлов в среде углекислого газа на примере систем Ti – O и Fe – O

The issues of decarbonization, which have recently received increased attention from the world community, mainly due to global warming, require the search for new solutions related to the utilization of carbon dioxide. The main problem of carbon dioxide conversion is the need to overcome the high stability of its molecules that requires the supply of a significant amount of energy. This paper presents the experimental results on the high-energy plasma dynamic synthesis of metal oxides in a carbon dioxide medium using the Ti – O and Fe – O systems as an example. By applying a sectioned capacitive energy storage device and a coaxial magnetoplasma accelerator with titanium and steel electrodes, which are the main elements of the plasma dynamic synthesis system, nano- and micropowders of iron and titanium oxides were obtained by utilizing CO2. Synthesis of powders was carried out as a result of plasma-chemical reactions occurring during high-speed sputtering of carbon electric discharge plasma into the atmosphere of a reactor chamber filled with carbon dioxide. The possibility of controlling the volume of CO2 utilized in the synthesis process by changing the type of electrodes and the number of successive power supply pulses is shown. It has been established that when using titanium electrodes and a multi-pulse operating mode in the considered system, it is possible to utilize up to 15 vol. % of CO2 to obtain up to ~ 9 g of dispersed products. It should be noted that when titanium electric discharge plasma is sputtered in a CO2 medium, the formation of “classical” rutile and anatase phases, as well as Magneli phases and titanium carbide without traces of pure metal is observed. This indicates that when implementing the plasma dynamic synthesis, it is possible not only to utilize carbon dioxide, but also to obtain useful powder products, which can later be used as feedstock for various applications.

MANAGEMENT STRATEGIES FOR ENERGY PROCESSES IN ELECTRIC ROLLING STOCK WITH ON-BOARD ENERGY STORAGE DEVICES

The article deals with the main existing strategies for management strategy of energy exchange processes in the electric rolling stock with onboard capacitive energy storage devices. When considering strategies, it is assumed that the onboard capacitive storage has low power and capacitance. Therefore, this capacitor storage is not able to accept the full amount of regenerative braking energy of the electric rolling stock. The purpose of the paper is to consider and analyze management strategies for energy exchange processes in the electric rolling stock with onboard capacitive energy storages; to define the advantages and disadvantages of each of the existing strategies and propose a concept for the effective management of energy exchange processes in the electric rolling stock. The block diagram of electric rolling stock with the onboard capacitive energy storage which is used for the analysis of management strategies for energy exchange processes is presented. The modes of operation of electric rolling stock with onboard capacitive energy storages are described. Five main strategies for management of energy exchange processes on the electric rolling stock with onboard capacitive energy storages are determined. The advantages and disadvantages of each strategy are set out taking into account the given conditions (characteristics of the electric rolling stock, conditions of the rolling stock motion, oscillograph charts, etc.). The general advantages and shortcomings of each strategy are defined, which allowed to propose the concept of creating an adaptive strategy for managing energy exchange processes in electric rolling stock with onboard capacitive energy storages. The main concept of this management strategy is to implement efficient energy exchange between the traction equipment, the onboard capacitive energy storage, the overhead contact system, both in normal and emergency modes of traction power supply, taking into account the dynamics of energy exchange processes in the overhead contact system, which will generally allow safety and energy efficiency of the transportation process. The obtained research results will contribute to the development and implementation of effective strategies for managing energy exchange processes in the electric rolling stock.