High Power Capacity Research Articles

Layered Structure Modification of Sodium Vanadate through Ca/F Co‐Doping for Enhanced Energy Storage Performance

AbstractVanadate materials are promising for sodium‐ion batteries (SIBs) due to their low cost, high capacity, and high power characteristics enabled by vanadium's multiple oxidation states. However, their development is hindered by poor conductivity, suboptimal high‐rate performance, and limited cycle life. In this work, a layered structure modification strategy involving Ca/F co‐doping in sodium vanadate Na2CaV2O6F (CVF) is proposed to address these issues. Through a combination of experiments and density functional theory calculations, it is demonstrated that Ca/F synergies enhance the Na layer spacing in CVF, resulting in reduced crystal water content and volume shrinkage compared to Na2V2O6 (NVO). Additionally, Ca/F incorporation significantly mitigates the diffusion potential of Na+ within the material framework. The unmodified CVF sample exhibits a high reversible capacity of 220 mAh g−1 at 10 mA g−1 and an excellent rate capacity of 65.78 mAh g−1 at 400 mA g−1. Furthermore, the cathode material maintains a capacity of up to 138 mAh g−1 at 200 mA g−1 and retains 104.88 mAh g−1 after 100 cycles within the voltage range of 1.5−4.0 V. These findings enhance the understanding of the crystal structure of NVO cathode materials and pave the way for the rational design of high‐quality vanadate cathodes for SIBs.

Comparative analysis and optimal allocation of virtual inertia from grid‐forming and grid‐following controlled ESSs

AbstractA broad consensus of neutralizing the carbon dioxide emissions facilitates the transition to the renewable energy power system. Meanwhile, the concerns about the volatility of renewable energies are growing as the rotational inertia of power system becomes inadequate. To maintain the frequency stability of power system, some studies for configuring inertia energy storage systems (ESSs) are carried out, mainly focusing on the allocation of virtual inertia from grid‐forming ESS. In contrast, the allocation of virtual inertia from grid‐following ESS has not been well elaborated and the differences in virtual inertia provided by these two modes are yet to be revealed. Based on ‐norm and Kron reduction, firstly, the state‐space model of post‐disturbance system is established, together with the transient performance evaluation. Then the inertia characteristics of both grid‐forming and grid‐following devices are formulated, followed by the unified gradient descent optimization method for allocating virtual inertia. A modified IEEE 39‐bus system and its time‐domain simulations help in the verification of the contribution of this paper. Through the comparative analysis of corresponding optimal results, the conclusions from two aspects are drawn: in terms of transient frequency support, the grid‐forming devices can provide no less than better inertia support; with the higher power capacity and similar energy capacity, the grid‐forming devices can relieve the response pressure of other generators by approximately .

A Five-Level Common-Ground Inverter with Dynamic Voltage Boost and Fewer Elements for Photovoltaic Applications

Transformer-less multilevel inverters (TL-MLIs) are the subject of recent research due to their high-voltage or high-power capacity to convert low-voltage output from renewable energy sources into the desired output. They are also less expensive and smaller than traditional varieties. Nevertheless, leakage current is a common problem with these inverters. The proposed inverter aims to address this issue to the maximum extent possible. In the proposed inverter structure, there is a common ground for the input and output terminals. As a result, the overall common mode voltage (CMV) remains constant. This common ground feature short-circuits the Photovoltaic (PV) source to the grid parasitic capacitor, resulting in negligible leakage current. Furthermore, the proposed inverter boosts output voltage using the least amount of power devices and a single voltage source. The proposed inverter can be used modularly, increasing the number of output levels that can be achieved. The simulation results from MATLAB/Simulink and the conclusion of the mathematical analysis for the proposed inverter are shown. The results also demonstrate the output voltage boost capability, zero leakage current, and an appropriate total harmonic distortion for the output voltage and current waveforms.

Method for constructing typical operation scenarios in power systems considering spatiotemporal correlation of renewable energy generation

Abstract The proposed article focuses on developing a methodology for constructing typical operational scenarios in power systems considering the spatiotemporal characteristics of new energy output. The integration of new energy sources on a large scale into power systems can lead to issues such as line congestion and supply-demand imbalances. To support the planning and scheduling of future high-capacity power systems, this paper introduces a method that accounts for the spatiotemporal characteristics of new energy outputs. The method begins by proposing a spatiotemporal fusion-based multi-head attention model for generating new energy output scenarios. This model employs multi-head attention mechanisms to extract the spatiotemporal characteristics of new energy outputs, eliminating redundancy in the feature data. The processed spatiotemporal feature information is then transferred to a gated feature fusion model for integration, using an encoder structure based on Long Short-Term Memory (LSTM) to generate new energy output scenarios. The paper, by means of an advanced Fuzzy C-Means (FCM) clustering algorithm, identifies typical scenarios of net energy output. Subsequently, the proposed method’s efficacy and precision are confirmed through simulation analysis with real data from a certain area.

Development of environmentally friendly high-capacity power cables

Development of environmentally friendly high-capacity power cables

An LCC-CS bilateral matching network for high efficiency energy conversion in high-frequency piezoelectric rotary ultrasonic machining system

The processing efficiency and machining quality of piezoelectric rotary ultrasonic machining (PRUM) system are closely related to its electromagnetic energy conversion units and electroacoustic energy conversion units. Generally, the high efficiency and high-power capacity of PRUM systems are limited by several energy conversion devices including the capacitive piezoelectric transducer (PT) load, loosely coupled rotating transformer (RT), and non-soft switching inverter. This article improves the overall performance of high-frequency PRUM system by bilateral matching network. On the rotating side, the compared results of five different static matching schemes show that the CS matching scheme ensures stable and efficient vibration of capacitive PTs even under incomplete matching. On the stationary side, a dynamic LCC matching scheme is adopted to keep the output impedance angle of H-bridge inverter in the weak inductive state. Finally, the proposed high-order matching network in this article makes the efficiency of high-frequency PRUM system over 90 % steadily.

Analysis of the Impact of Forces in Hanger Rods on Power Boiler Operation

Hanger rods intended for boiler suspensions on a metal structure require a special design approach that considers the total weight of the boiler structure that is to be carried. Unfortunately, a large reserve in the rods’ carrying capacity does not always guarantee the failure-free operation of a boiler. For this reason, it is very important to monitor the forces acting in the rods. Any negligence in this matter might cause a local excess of stresses in the boiler pressure part and result in periodic shutdowns of the boiler. Therefore, in order not to let this happen, adequate computational methods have to be developed. To date, the methods described in the literature and in design requirements have concentrated, first of all, on analyses of the boiler individual subassemblies or on small boiler units supported from the bottom at just a few points. The aim of this paper was to conduct a numerical analysis for a real high-capacity power boiler. The computations were performed based on experimentally measured forces in the hanger rods, and the results were verified by comparing the areas of stress concentration against the area where the boiler structure was regularly damaged.

Static Strength Assessment of Turbine Blades in High-Capacity Power Units

Static Strength Assessment of Turbine Blades in High-Capacity Power Units

Power hardware-in-loop emulation of a battery for charging systems and grid applications

Relevance. Batteries are playing an increasingly vital role in power systems due to their utilization in various applications including microgrids, electric vehicles, sustaining geographically isolated communities, and energization of automated devices. Since they are considered as the enabling technology for renewable energy integration, the absence of battery systems from islanded microgrids can result in decreased system reliability and compromised performance due to the intermittency of local sources. Nevertheless, the hazardousness associated with their charging mechanism has led to the urgent continuous development of charging technologies and battery management systems. Aim. To develop a safe testbed to examine the functionality of newly produced battery charging stations and battery managers without employing actual physical batteries to avoid the hazardous manipulation of batteries and increase flexibility during the design and validation stage. This is accomplished by modeling the electrochemical dynamics of the battery system and integrating the device-under-test to a DC converter, which reacts based on these modeled dynamics. Novelty. This work adapts one of the most successful Li-ion battery models available in the literature and utilizes it to interact with power electronic devices that exchange power signals. Unlike other work in this field, the design is based on power hardware-in-loop principles and has minimized power consumption characteristics due to its unique configuration. The constructed computer model can be easily reparametrized to describe the dynamics of various battery capacities. Methods. MATLAB-based simulations of the proposed testbed were conducted for high and low power capacity. A LabView-based program was interfaced with the testbed hardware using a NI-DAQ board to validate the proposed design practically. The testbed hardware components were entirely developed from scratch for experimentation purposes. Results. The proposed testbed successfully imitated the dynamics of the battery, while the practical results concurred the simulated ones.

Performance analysis of 4QAM-OFDM-FSO link under rain weather conditions

Abstract Free space optical communication (FSO) is a technique based on transmission of data by propagating the light in free space. FSO is inexpensive, providing high data rates, high capacity, high security, and low power and uses the license free frequency spectrum. Nevertheless, FSO is still facing many problems such as bad weather conditions, atmospheric turbulence, and multipath fading. In this research work, orthogonal frequency division multiplexing (OFDM) FSO system is analyzed for low to heavy rain fall intensities. Different rain rates have been considered for low, moderate, heavy, very heavy, and torrential rains. For all the rain rates, a direct detection OFDM–FSO system and a coherent detection system have been simulated and results are compared. Analysis has been done on the basis of SNR, received power, and constellation diagrams. According to these parameters, link length of both the systems for different rain rates was found. Coherent detection is applied to improve the system sensitivity compared to conventional direct detection. In tropical regions where heavy rainfall is the main reason for the degradation of the system, the OFDM system with coherent detection can perform better with high data rates. Second, over a 11 km FSO, a 4-QAM wireless signal is successfully transmitted under very heavy rainfall conditions. The distance achieved by moderate and heavy rains is 25 km and 15.5 km with an acceptable SNR of 25 dB and a system sensitivity (received power) of −65.1 dBm.

Stabilizing Layered‐Type K0.4V2O5 Cathode by K Site Substitution with Strontium for K‐Ion Batteries

AbstractDeveloping suitable cathodes with high capacity and high power is challenging for K‐ion batteries. Herein, electrochemical K‐ion storage properties of the layered‐type K0.4V2O5 (KVO) cathode by incorporating divalent strontium ions (Sr2+) into its crystal structure are enhanced. Divalent strontium ions (1.18 Å) are preferentially incorporated into the octahedrally coordinated K (1.38 Å) layers due to the similar ionic size compared to V4+ (0.58 Å). The introduction of 3 mmol of Sr ions in the KVO crystal improves electrical conductivity and reduces K‐ion diffusion energy barriers. In addition, the strong Sr2+ and O2− interaction acts as a structural pillar, suppressing irreversible phase transition during charge–discharge process. Multi‐physics simulations clearly confirm that the K0.34Sr0.03V2O5 (KS3VO) cathode exhibits a more uniform K‐ion distribution and enhanced reactions of K‐ions compared to the KVO cathode at various depths of discharge. As a result, the KS3VO cathode demonstrates improved reversible capacity, cycling stability, and power capability over the KVO cathode in a K‐ion cell. Synchrotron X‐ray analysis reveals how Sr substitution enhances the electrochemical K‐ion storage properties of the KS3VO cathode. In addition, the KS3VO cathode exhibits superior thermal stability and cycling stability in a full cell coupled with a hard carbon anode compared to the KVO cathode.

Solar Based Wireless Power Transmission for Electric vehicle Charging Station

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimetres to several hundred millimetres with a grid to load efficiency above 90%. The advances make the WPT very attractive to the electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. For energy, environment, and many other reasons, the electrification for transportation has been carrying out for many years. In railway systems, the electric locomotives have already been well developed for many years. A train runs on a fixed track. It is easy to get electric power from a conductor rail using pantograph sliders. However, for electric vehicles (EVs), the high flexibility makes it not easy to get power in a similar way. Instead, a high power and large capacity battery pack is usually equipped as an energy storage unit to make an EV to operate for a satisfactory distance. The problem for an electric vehicle is nothing else but the electricity storage technology, which requires a battery which is the bottleneck today due to its unsatisfactory energy density, limited lifetime and high cost. Keywords: Wireless Power transfer, Electric Vehicle, Battery

Zero carbon emission CCGT power plant with integrated solid fuel gasification

The development of a high-capacity power plant with zero CO2 emissions is an urgent task that will curb the increase in atmospheric temperature. It should have an efficiency comparable with existing TPPs, a low metal consumption rate, a high fuel versatility, and high flexibility. To meet these conditions, oxygen combustion is conducted in an environment of inert CO2, and most of the condensation heat from the combustion products is usefully utilized. This work presents a combined cycle gas turbine (CCGT) power plant with solid fuel gasification, oxy-fuel combustion, and a pressurized heat recovery steam generator (PHRSG). The two plant options are compared with the natural gas plant previously proposed. In the PHRSG, the low metal intensity is achieved by high average temperature differences, the pinch point value at 8–12 °C, and the intensification of heat transfer caused by the high pressure of combustion products and the condensation of water vapor in the tail surfaces. The developed plants are highly efficient when using coal, 51%, and 57.3% when using peat, and have acceptable CO2 avoidance costs of 72.7 €/t and 60.4 €/t. By combining these factors, and using well-developed materials, it will take less time to develop and implement this plant widely.

Economic comparison of loblolly pine and solar power in South Georgia, United States

In the face of deforestation from urbanization and population growth, there is a potential for an additional loss of forests from solar power generation as forest landowners may look to alternative sources of income. We compare the profitability of loblolly pine (Pinus taeda) plantations and solar power generation in South Georgia. The analysis was completed at two different scales, one acre (0.405 ha) and five acres (2.02 ha), based on the large number of small acreage forest landowners in the state. The Land Expectation Values (LEVs over 25 years project cycle) for a 350 kW (occupying one acre or 0.405 ha) and a 1 MW (occupying five acres or 2.02 ha) solar power systems are -$30,183 and $29,607 at an 8 % interest rate, respectively. In comparison, LEVs for one acre (0.405 ha) and five acre (2.02 ha) loblolly pine stands (at the site index 80 ft/24.4 m) for the same rotation cycle are $1,380 and $6,900 at a 6 % interest rate and $611 and $3,055 at an 8 % interest rate, respectively. The potential profitability of solar power systems varies, depending on whether the solar generation and pricing are high enough to overcome the significant installation, upkeep, and recycling costs. Since the potential profitability of the larger-scale solar power systems is significantly higher than loblolly pine stands at around five acres, there is a chance that small family forest landowners could convert their forestlands into solar farms, especially if their forestlands are close to a high-capacity power transmission line. This information could feed into ongoing policy deliberations on promoting conservation and renewable energy generation at the state level and beyond.

The enhancement of explosive power contributes to the development of anaerobic capacity: A comparison of autoregulatory progressive resistance exercise and velocity-based resistance training

Background/ObjectivesDue to the character of the taekwondo, the adenosine triphosphate–phosphocreatine system provides the energy for each kick, the glycolytic system supports the repeated execution of kicks, and the aerobic system promotes recovery between these movements and the bout. Therefore, taekwondo athletes require high explosive power and anaerobic capacity in order to carry out sustained and powerful attacks. So, the purpose of this study is to compare the effects of APRE and VBRT on lower-limb explosive power and anaerobic capacity in college taekwondo players. MethodsA total of 30 taekwondo players completed an 8-week training intervention with autoregulatory progressive resistance exercise (APRE; n = 15) and velocity-based resistance training (VBRT; n = 15). Testing included the one-repetition maximum squat, countermovement jump (CMJ), taekwondo anaerobic intermittent kick test (TAIKT), and 30-s Wingate anaerobic test (WAnT). Results(1) Intragroup comparisons revealed significant effects for one-repetition maximum squat, peak power of CMJ (CMJPP), relative peak power of CMJ (CMJRPP), and total number of TAIKT (TAIKTTN) in both the APRE and VBRT groups. The VBRT group exhibited small effect sizes for time at peak power of WAnT (WAnTPPT) and moderate effect sizes for peak power of WAnT (WAnTPP), relative peak power of WAnT (WAnTRPP), and fatigue index of TAIKT (TAIKTFI), whereas the APRE group exhibited small effect sizes for TAIKTFI. (2) Intergroup comparisons revealed no significant effects in any of the results. However, VBRT demonstrated a moderate advantage in WAnTPP and WAnTRPP, whereas APRE had a small advantage in CMJPP and CMJRPP. ConclusionsThese findings suggest that APRE improved explosive power (CMJPP and CMJRPP) more, whereas VBRT improved anaerobic power output (WAnTPP and WAnTRPP) more. Both methods were found to have similar effects in improving the anaerobic endurance (WAnTPPT and TAIKTTN) and fatigue index (power drop of WAnT and TAIKTFI).

A Compact Broadband Power Combiner for High-Power, Continuous-Wave Applications.

A compact broadband combiner with a high power capacity and a low insertion loss, which is especially useful for solid-state power sources where multi-way power synthesis is needed, was designed and experimentally investigated. The combiner could combine the microwave signals of sixteen terminals into a single one and was based on a radial-line waveguide whose circumferential symmetry benefited the amplitude and phase consistency of the combiner. Simulation and experimental results showed that the prototype device, designed for S-band applications, exhibited a reflection coefficient S1,1 < -20 dB in the range of 2.06-2.93 GHz, which corresponds to a relative bandwidth of approximately 34.6%. At 2.45 GHz, the phase imbalance was ±4.5° and the 16-way transmission coefficient was concentrated around -12.0~-12.3 dB. The insertion loss of the device at ambient and elevated temperatures was simulated and experimentally verified, which is of importance for the design of similar high-power microwave combiners. High-power tests proved that even without enforced wind or liquid cooling, the device can handle continuous power (CW) of at least 3.9 kW, which can be much enhanced by taking regular cooling measures. The combined features of the designed combiner suggest promising applications for power synthesis in high-power, solid-state RF sources.

Engineering Hierarchical Interface in High-temperature Polymer Dielectrics for Electrostatic Supercapacitors

Dielectric capacitors are pivotal elements in advanced pulsed power devices and high-voltage high-capacity power electronic converters, crucial for efficient energy storage. However, a major challenge remains the significant reduction of...

A novel elastic strip suspension-based bi-directional electromagnetic wind energy harvester designed specifically for wind energy factories

In this study, we propose a novel parallel elastic strips suspended electromagnetic wind energy harvester (ESWEH) based on wind-induced vibration. Profiting galloping phenomena caused by wind flow, the hollow square tube is conceived to generate a significant transverse vibration, and two magnets are equipped on the hollow square tube to generate electrical energy utilizing the electromagnetic induction principle. The symmetrical design of the ESWEH enables it to harvest bi-directional wind energy, while this structure is easy to be assembled into an integrated energy harvesting factory to meet various power supply requirement. A theoretical model is developed to explain the operational mechanism of the proposed electromechanical coupling system. Further, a series of experiments are conducted in a wind tunnel to examine its power generation characteristics (including power-resistance, voltage-resistance) under a closed-circuit condition. The results of the experiments indicate that, when the wind velocity exceeds 2 m/s, the ESWEH equipped with both front and back attached fins produces a continuous and stable current output, with a voltage value exceeding 2.0 V and power exceeding 2.0 mW. Moreover, at an incoming wind velocity of 4 m/s, anaverage power of 7.8 mW is obtained, accompanied by a Root Mean Square (RMS) voltage of 3.2 V when connected to a resistance of 1.2 kΩ. In conclusion, the proposed ESWEH shows good performances in various aspects such as a simplified structure, efficiency-cost, low critical wind velocity and a high-power capacity. The experimental results further indicate that the proposed structure has potential application in construction of a stable power supplying system and wind energy factory for wireless sensors.

Seismic events in the Sverdlovsk region for the period 1788–2022

Introduction. Sverdlovsk region is a major industrial center. There are mining enterprises, chemical plants, reservoirs, and high-capacity power plants. These objects are located close to large settlements. Currently, about 400 seismic events are recorded annually in the region. To ensure the seismic safety of objects of increased responsibility and especially important construction objects, it is necessary to carry out studies on detailed seismic zoning of the territory under consideration. The results of this work are the first stage of these studies. Research theory. For the first time, a consolidated unified catalog of seismic events that occurred on the territory of the Sverdlovsk region was compiled. Historical and instrumental catalog data for the period 1788–2022 and data from instrumental records of local seismic events recorded by temporary, mobile stations of the Institute of Geophysics Ural Branch of the Russian Academy of Sciences (IGF UB RAS) served as the basis. served as the basis. Results. Most of the recorded events are technogenic. Mostly these are industrial explosions and rock burst. These seismic events are recorded in the area of the following cities: Asbest, Ekaterinburg, Revda, Nizhny Tagil, Kushva, Kachkanar, Karpinsk, Severouralsk. Tectonic earthquakes have also been repeatedly recorded in the Sverdlovsk region. Most of them are not felt by people. Earthquakes with a magnitude greater than 4.0 have macroseismic manifestations. The strongest earthquake is 08.17.1914 (MS= 5.0, epicenter coordinates 57.09° N, 59.8° E). The intensity of the earthquake at the epicenter was 6.0 on the MSK-64 scale. The results of this work will serve as a basis for further determination of the parameters of the seismic regime of the study area.

An experimental investigation design of a bidirectional DC-DC buck-boost converter for PV battery charger system

The aim of this paper is to present a bidirectional DC-DC buck-boost converter design that is specifically intended for use with storage batteries in a PV system. The primary purpose of the batteries is to mitigate the unpredictable and intermittent nature of renewable energy sources. To achieve this, a DC-DC converter is used in buck mode during daylight hours to charge the batteries with power derived from the PV system. If the photovoltaic energy source is unavailable, the batteries can discharge to power the DC load through the converter in boost mode. Therefore, the bi-directional DC/DC converter, which has a high-power capacity, manages the power storage system. To this end, the paper describes the design and implementation of both the power circuit board and drive circuit board of the buck-boost converter, taking into account the rated current, voltage, and power. Finally, the effectiveness and efficiency of the designed converter are verified through experimental tests carried out in both charge and discharge modes, with results demonstrating the validity and efficiency of the converter.