Direct Current Energy Research Articles

Simulation of PSDF (Photovoltaic, Storage, Direct Current and Flexibility) Energy System for Rural Buildings

The PSDF (photovoltaic, storage, direct current, and flexibility) energy system represents an innovative approach aimed at achieving carbon neutrality. This study focused on rural buildings and utilized Modelica to develop a dynamic simulation model of the PSDF system. The research introduced a framework for direct current distribution microgrid systems with flexible regulatory mechanisms, employing a virtual inertia control strategy to provide stable adjustments for flexible operations and support integration with local grids. Case simulation results indicated that the system equipped with a water tank saved 3.15 kWh compared to the system without a water tank, resulting in an energy savings rate of 22.14%. Compared to traditional photovoltaic systems, the PSDF system significantly enhanced energy management flexibility and system reliability through the integration of thermal storage and battery management. This research made significant contributions to the fields of renewable energy and building energy systems by offering a scalable and practical solution suitable for rural contexts.

Direct Current Ripple Component Detection Algorithm Based on Improved Variational Mode Decomposition

Background: The development of smart grids requires energy meters that enable accurate measurements. Objective: In response to the current issue where Direct Current (DC) energy meters only measure DC components and not ripple components, we propose to design a novel algorithm to achieve accurate separation of DC components and ripple components in DC signals. Methodology: This patent proposes a precise detection algorithm for ripple components. The algorithm is based on the Wavelet Decomposition combined with Flamingo Search Algorithm-Variational Mode Decomposition (WD-FSA-VMD). Firstly, we analyze the ripple characteristics in the DC signal and use the Wavelet Decomposition (WD) algorithm to separate the ripple components in the DC signal accurately. Secondly, we utilize the Flamingo Search Algorithm (FSA) to optimize the number of modal decompositions and the penalty factor in the Variational Mode Decomposition (VMD). This allows us to accurately extract the ripple components. Finally, we conducted simulation experiments comparing the improved algorithm with the original algorithm. Results: The experimental results indicate that the signal correlation coefficient obtained by the WDFSA- VMD algorithm increases by 82.64% compared to traditional VMD, and it increases by 16.72% compared to the combined Wavelet Decomposition with Whale Optimization Algorithm-Variational Mode De-composition (WD-WOA-VMD). Conclusion: The improved algorithm we proposed has good adaptability and separation performance. It is prospective for the new algorithm to provide a valuable reference to ripple detection technology.

20 Seconds to fabricate high-performance NiFe-based anode for seawater electrolysis via bidirectional pulse current method

Direct electrolysis of seawater to produce green hydrogen has attracted great attention. While the development of efficient and rapid manufacturing processes for high-performance electrodes, particularly for the oxygen evolution reaction (OER), remains trail. Here, we introduce an innovative approach to fabricate high-performance NiFe-based OER electrodes using an ultrafast and eco-friendly bidirectional pulse current (BPC) method, which remarkably shortens the production time to only 20 s. Our BPC method alternates oxidation and reduction currents within a single period, promoting the in-situ formation of porous NiFe(oxy)hydroxide nanosheets through dissolution/deposition processes. Moreover, this methodology creatively utilizes the “Cl− induced effect”, typically a hindrance in other electrochemical systems involving seawater or brine, to enhance the synthesis of electrodes from NaCl-based electrolyte devoid of additional Ni/Fe cations. The prepared NiFe-based electrode (NFF O-R 20 s) demonstrates remarkable OER catalytic activity, with optimal overpotentials (ηj) of 272, 308 and 367 mV at current densities (j) of 10, 100 and 1000 mA cm−2, respectively. Impressively, it maintains a low cell voltage of 1.59 V after enduring 1000 h of operation under the industrially current density of 300 mA cm−2, with a direct current energy consumption of 3.8 kWh Nm−3 H2 for overall alkaline seawater electrolysis. Our BPC preparation approach provides a promising path to construction high-catalytic activity, good-stability electrode, and low-energy consumption direct seawater electrolyzer.

Battery Analysis in Off Grid Solar Power Plant as A Power Source for AC Motor Automatic Coffee Roaster Machine Capacity 20 Kg

Solar power plants that utilize solar energy to be converted into electrical energy have several advantages compared to other power plants, namely that they do not produce air pollution, are available continuously and are available everywhere. Coffee is a commodity in the world that is cultivated in more than 50 countries. Two species of coffee trees that are generally known are Robusta Coffee and Arabica Coffee. Processing coffee before consumption goes through a long process, namely from harvesting coffee beans that are ready to harvest. Then proceed with drying before roasting. Coffee roasting machine that uses an AC motor. The motor gets a DC power source from a solar power plant then the inverter changes the DC voltage to AC. This coffee roasting machine is equipped with IoT to control the motor rotation remotely and monitor the temperature. The battery has the function of storing electrical energy produced by solar panels in the form of direct current energy. The energy stored in the battery functions as a backup, which is usually used when the solar panels do not produce electrical energy. The greater the capacity of the battery used, the longer the battery can back up the load used.

Development of an Automatic Scissors Screw Car Jack

In this paper, an existing manual scissors screw car jack was converted to an automatic scissors screw car jack by introducing a sleeve coupling between the manual screw jack and a 12V DC electric motor, which is powered through a direct current energy flow directly from the car battery. The DC electric motor provides a turning effect to automatically power the screw jack for the purpose of lifting the desired load. A screw jack (manual or automatic) is a simple machine used in lifting heavy loads. It becomes very useful in vehicles when changing a punctured tire. It is mandatory for each vehicle plying an approved road to carry a jack for fixing a punctured tire. However, the operation of most car jacks is done manually and also requires prolonged bending or squatting positions when using the jack, making it difficult for most women, the disabled, the elderly, etc., and above all, not ergonomically suitable for the human body due to crouching and squatting positions when in use, which may result in health complications. The automatic scissors car jack developed was successfully tested on five different types of vehicles, with different weights. Five different tests measurements were carried out on each vehicle. The time taken to lift the vehicles 0.03 m off the ground was recorded. They ranged from 74 s to 90 s depending on the weight of the vehicle involved. The heavier the vehicle, the longer the time taken to lift the vehicle off the ground to the predetermined height of 0.03 m.

Facile Immersing Synthesis of Pt Single Atoms Supported on Sulfide for Bifunctional toward Seawater Electrolysis

Seawater electrolysis for hydrogen production represents a substantial opportunity to curtail production expenditures and exhibits considerable potential for various industrial applications. Platinum-based precious metals exhibit excellent activity for water electrolysis. However, their limited reserves and high costs impede their widespread use on a large scale. Single-atom catalysts, characterized by low loading and high utilization efficiency, represent a viable alternative, and the development of simple synthesis methods can facilitate their practical application. In this work, we report the facile synthesis of a single-atom Pt-loaded NiCoFeSx (Pt@NiCoFeSx) bifunctional catalytic electrode using a simple impregnation method on a nickel foam substrate. The resulting electrode exhibits low overpotentials for both HER (60 mV@10 mA cm−2) and OER (201 mV@10 mA cm−2) in alkaline seawater electrolytes. When incorporated into a seawater electrolyzer, this electrode achieves a direct current energy consumption of only 4.18 kWh/Nm3H2 over a 100 h test period with negligible decay. These findings demonstrate the potential of our approach for industrial-scale seawater electrolysis.

The new "olive strategy" for pulsed field ablation of atrial fibrillation: procedural data and early follow-up

Abstract Background Pulsed field ablation (PFA) is a new myocardial-specific ablation technology for atrial fibrillation (AF). Direct current electric energy is applied to cells and disrupts cell membranes by creating pores. Purpose The aim of this single-center study was to report procedural data and early recurrence of atrial tachyarrhythmia (ERAT) following a new PFA-based ablation strategy for pulmonary vein isolation (PVI). Methods Consecutive patients with symptomatic AF were enrolled to undergo PFA-PVI using the pentaspline catheter. A new ablation strategy was performed: In total 10 applications per pulmonary vein (PV) were delivered. In addition to the conventional four applications in flower- and four applications in basket-configuration, two applications were delivered in a smaller "olive"-configuration. ERAT was defined as any documented AF/atrial tachycardia (AT) lasting more than 30 seconds during a 90-days blanking period. Procedural and demographic data were analysed. Results 60 patients (37% female, age 67±12, 43% paroxysmal atrial fibrillation [PAF]) were included in this preliminary analysis. 239 PVs were identified, and all PVs could be isolated using solely the PFA device. All PVs were isolated with the first application. 40 applications per patient were delivered. No complications occurred. Procedure time was 30±11 min, fluoroscopy time was 6±3 min. Median follow-up time was 100 days. 20% of patients experienced an early recurrence after a median of 2 days (IQR 1-7.25; 92% AF, 8% AT). Kaplan Meier estimated freedom of AF/AT was 83.3 % at 3 months, 92.3% for PAF and 76.5% for persistent atrial fibrillation (p=0.11). Conclusions Our data show feasibility of a new ablation strategy with the pentaspline PFA-catheter. This study indicates high acute efficacy and safety. 83.3% of patients are free of AF/AT at 3 months. Longer follow-up times are needed to assess the clinical outcome and will be available at the time of presentation.

Large-Scale and Simple Synthesis of NiFe(OH)x Electrode Derived from Raney Ni Precursor for Efficient Alkaline Water Electrolyzer

Water electrolysis is a crucial technology in the production of hydrogen energy. Due to the escalating industrial demand for green hydrogen, the required electrode size for a traditional alkaline water electrolyzer has been increasing. Numerous studies have focused on developing highly active oxygen evolution reaction (OER) catalysts for water electrolysis. However, there remains a significant gap between the microscale synthesis of catalysts in laboratory settings and the macroscale preparation required for industrial scenarios. This challenge is particularly pronounced in the synthesis of sizable self-supported electrodes. In this work, we employed a commercially available Raney Ni-coated Ni mesh as a precursor material to fabricate a self-supported NiFe(OH)x@Raney Ni anode with a substantial dimension exceeding 300 mm through a straightforward immersion technique. The as-prepared electrode exhibited remarkable electrocatalytic OER activity, as an overpotential of only 240 mV is required to achieve 10 mA cm−2. This performance is comparable to that of NiFe-LDHs synthesized via a hydrothermal method, which is difficult to scale up for industrial applications. Furthermore, the electrode demonstrated exceptional durability, maintaining stable operation for over 100 h at a current density of 500 mA cm−2. The large-scale electrode displayed consistent overpotentials across various areas, indicating uniform catalytic activity. When integrated into an alkaline water electrolysis device, it delivered an average cell voltage of 1.80 V at 200 mA cm−2 and achieved a direct current hydrogen production energy consumption as low as 4.3 kWh/Nm3. These findings underline the suitability of electrodes for industrial scale applications, offering a promising alternative for energy-efficient hydrogen production.

Advanced Management of Electric Vehicle Charging Conditions Utilizing a Photovoltaic-Based Multi-Mode Converter System

The surging popularity of electric vehicles (EVs) as an environmentally friendly mode of transportation has heightened the need for conveniently situated charging stations, since EVs have limited range on their internal batteries. Fast charging stations, especially super-fast charging stations, may strain the power infrastructure owing to the risk of overload during peak hours, sudden power interruptions, and voltage drops. This work examines the detailed modeling of a direct current (DC) power generation and battery energy storage system integrated into a multiport converter-based electric vehicle (EV) charging station. This project assesses the feasibility of utilizing Plug-in electric vehicles (PEVs) in Vehicle to Home (V2H) scenarios as a means of residential battery storage or backup generator during power outages or distribution system faults, which are typically of shorter duration. Both the simulated and experimental results validate the feasibility of PCMM and demonstrate its capacity to accomplish the design objective. The charger has been designed and its operation validated using a space vector modulation technique and a simulation analysis. The simulation findings indicate that the proposed charger and a compatible autonomous EMS would interact well in a typical residential setting.

Theoretic and experimental performance of a grid-connected photovoltaic system: Multiple prediction model of efficiency and annual energy generation

In this article, the performance of a 3.36 kWp grid-connected photovoltaic system (GCPVS) under warm and subhumid weather conditions and the development of a predictive mathematical model is presented. Climate data of the 2021 year were used to evaluate energy generation, different types of performance, and efficiency. The average annual yield, corrected yield, array, and final yields were 6.45 h/day, 6.18 h/day, 5.16 h/day, and 4.97 h/day, respectively. The overall annual mean capacity factor and efficiency ratios were 20.73% and 77.22%, correspondingly. Experimental data were analyzed and correlated by multivariate linear regression (MLR) prediction and simulation to validate models. The MLR analysis showed that the efficiency is highly dependent on the temperature of the PV modules and that climatic parameters significantly affect the efficiency and output electric power. The prediction models for PV module efficiency, system efficiency, and direct current energy exhibit an uncertainty of ±1.04%, ±0.57%, and ±35.38 kWh, one-to-one. The monthly generation was compared with results obtained by Energy3D simulation-free software, showing an absolute error of ±2.33 kWh. This information can be used as a methodological tool for predicting efficiency and power generation in direct current.

Research on 2.45 GHz Weak Energy Wireless Transmission with Tilted Groove Schottky Diodes

Energy conversion efficiency is a key index to evaluate microwave wireless energy transmission system, which indicates the capacity to transform microwave energy into direct current (DC) energy. In this paper, the primary component of the rectifier circuit design, Ge Schottky Diode (SBD), is optimized and designed from a structural standpoint in the context of wireless energy collection in the weak energy density of 2.45 GHz Wi-Fi band, with the aim of enhancing the efficiency of the rectifier circuit in the presence of weak Wi-Fi energy density. The PSPICE parameters of the designed SBD were extracted using the parameter extraction tool, and the Spice model of the developed SBD was built. Utilizing this model, the rectifier circuit was simulated using ADS to enhance its efficiency and confirm the effectiveness of the intended devices. The findings indicate a notable enhancement in the energy conversion efficiency of the new Ge Schottky diode within the weak energy working region.

Optimization of DC Microgrid Power and Energy Management in the Presence of Small-Scale Wind Turbine Integration and Renewable Load Shedding

Improvement of Direct Current Microgrid (DCM) Power and Energy Management is the methodical process of increasing the DCM system’s performance, dependability, and effectiveness. In this study, the suggested a Stochastic Dove Swarm Optimized Deep Reinforcement Learning Algorithm approach to estimate the availability of wind energy, allowing for proactive management tactics. Initially, the data was collected and preprocessed by performing min–max normalization to clean the unwanted data. Recursive Feature Elimination is used to determine the greatest informative attributes. This study analyzes the use of significant performance metrics, including accuracy (91%), precision (92%), recall (93%), Root Mean Square Error (0.154), Normalized Root Mean Square Error (0.0526), and Mean Absolute Percentage Error (4.21). The use of optimization methodology focuses on the seamless integration of SWTs and the application of renewable LS methods to ensure the efficient management of power and energy in DC microgrids. The intention is to keep operational expenses to a minimum while providing a stable and robust energy supply. To ensure power balance, which serves as the primary objective of the monitoring, it is considered imperative for carrying out electricity limitations in this instance of the energy excess generated by solar power plants and the small-scale wind turbine.

Interconnecting industrial multi-microgrids using bidirectional hybrid energy links

Sharing and exchange energy among nearby industrial microgrids are crucial, especially with high energy requirements for their production targets and costly energy storage systems that may be oversized for their operations. Facilitating energy exchange can provide an economic advantage for industrial production by utilizing cheaper energy sources and reducing production costs. This manuscript presents an efficient approach for transferring large energy packets with minimal energy losses using high-voltage direct current (HVDC) energy transmission. The manuscript methodology focuses on implementing an industrial multi-microgrid using a modular multilevel converter. This converter utilizes two power link channels: a three-phase AC and an HVDC link, creating a hybrid energy transmission between microgrids. When a substantial amount of energy to transfer, the HVDC method enhances overall efficiency by reducing copper losses and mitigating issues associated with the AC link, such as harmonics and skin effects. The modular multilevel converter topology offers high flexibility and the use of fewer converters. Additionally, the HVDC link eliminates distance restrictions for energy transfer between industrial microgrids. A case study illustrates the functionality of this topology, demonstrating optimized power transfer and decreased energy losses. This methodology allows industrial microgrids to enhance energy efficiency and productivity while minimizing operational costs.

Analysis of cerium substitution in Co–Sr based spinel ferrites for high frequency application

Spinel ferrites exhibit exceptional magnetic properties, making them a distinctive class of magnetic materials. The sol–gel technique was utilized for the synthesis of spinel ferrites with the chemical formula Co0.6Sr0.4CexFe2–xO4. Following that, a comprehensive X-ray diffraction analysis unveiled the crystalline cubic structure of the synthesized materials. Through the utilization of the M-H loop approach, the ferromagnetic attributes of ferrites were assessed, and the assimilation of rare earth elements led to substantial enhancements in saturation magnetization, remanence, and coercivity. Spinel ferrites with a high concentration of rare earth elements have improved direct current resistivity and activation energy. The logarithm of a material's resistance increased from 5.29 to 8.12 Ω⋅cm as cerium is added. With a change in the amount of cerium, the activation energy goes up from 0.19 to 0.29. By changing the frequency from 5.5 to 9.5 GHz, the dielectric characteristics were determined. As the frequency goes up, the dielectric constant goes down. Spinel ferrites that have been made better in every way can be used in high-frequency applications.

Application of Artificial Intelligence Algorithms in Multilayer Perceptron and Elman Networks to Predict Photovoltaic Power Plant Generation

This paper presents the models developed for the short-term forecasting of energy production by photovoltaic panels. An analysis of a set of weather factors influencing daily energy production is presented. Determining the correlation between the produced direct current (DC) energy and the individual weather parameters allowed the selection of the potentially best explanatory factors, which served as input data for the neural networks. The forecasting models were based on MLP and Elman-type networks. An appropriate selection of structures and learning parameters was carried out, as well as the process of learning the models. The models were built based on different time periods: year-round, semi-annual, and seasonal. The models were developed separately for monocrystalline and amorphous photovoltaic modules. The study compared the models with the predicted and measured insolation energy. In addition, complex forecasting models were developed for the photovoltaic system, which could forecast DC and AC energy simultaneously. The complex models were developed according to the rules of global and local modeling. The forecast errors of the developed models were included. The smallest values of the DC energy forecast errors were achieved for the models designed for summer forecasts. The percentage forecast error was 1.95% using directly measured solar irradiance and 5. 57% using predicted solar irradiance. The complex model for summer forecasted the AC energy with an error of 1.86%.

3D-printed conducting polymer hydrogel-based DC generator for self-powered electromechanical sensing

Self-powered electromechanical sensing has gained considerable attention for its potential to transform diverse applications, such as wearable electronics, robotics, artificial intelligence, and environmental monitoring. One promising technology emerging in this field is additive manufacturing of conductive hydrogels as elementary component for energy harvesting/storage, enabling robust, flexible, and biocompatible sensor devices. In this study, we demonstrate a continuous 3D printed conductive hydrogel-based energy harvesting device with triply periodic minimal surface (TPMS) architecture. Leveraging the feature of direct-current (DC) energy generation upon mechanical stimulation, the device is capable of self-powered sensing operations. The DC energy generation mechanisms are discussed with the consideration of multiple physiochemical factors. Notably, the printed 3D architected conductive hydrogel (3D-ACH) exhibits robust mechanical properties, providing high flexibility with over 50% compressive strain. Additionally, we explore its performance as a pressure/strain sensor to achieve self-powered sensing capabilities. The combination of 3D-printed conductive hydrogels and energy generation capabilities represents a promising approach towards achieving self-powered sensing capabilities.

MODERNIZATION OF THE HELIUM ION ACCELERATOR MICROWAVE POWER SUPPLY SYSTEM

The high-voltage rectifier modernization, which is part of helium accelerator (PSS-4) high-frequency system, is described. The rectifier supplies the pulse modulator with direct current energy. The valves of the modulator used are mercury thyratrons. Modernization involves replacing thyratrons with semiconductor diodes. In the article, a comparative analysis of the parameters of thyratrons and diodes, which are supposed to be replaced by thyratrons, is carried out, and the expediency of such a replacement is substantiated.

Enhanced Power Quality and Forecasting for PV-Wind Microgrid Using Proactive Shunt Power Filter and Neural Network-Based Time Series Forecasting

This research proposes a proactive Shunt power filter to enhance the energy quality of a microgrid’s distribution. The study aims to identify a suitable controller technique for increasing the compensating capacity of the active filter in a PV-Wind hybrid energy production system, enabling voltage management and stabilization in direct current energy conversion facilities. The proposed control system utilizes a modified fuzzy logic algorithm for an enhanced performance active shunt energy filter. Simulations in the SIMULINK and MATLAB model environment validate the effectiveness of the methods. Additionally, a neural network model with a scrolling time frame is proposed to address the nonlinearity and time-varying nature of electricity generation from PV modules. The adaptable forecasting model using the neural network outperforms fixed prediction models in accuracy and computational efficiency. This approach has the potential to significantly improve power quality and forecasting accuracy for real-world PV power production.

Early recurrences predict late therapy failure after pulsed field ablation of atrial fibrillation: midterm clinical outcome from a high-volume center

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) is a new myocardial-specific ablation technology for atrial fibrillation (AF). Direct current electric energy is applied to cells and disrupts cell membranes by creating pores. Data regarding midterm outcome are sparse. Purpose The aim of this single-center study was to report midterm clinical outcomes following PFA-based pulmonary vein isolation (PVI). Methods Consecutive patients with symptomatic AF were enrolled to undergo PFA-PVI based on the "5S Study" ablation strategy. Procedures were done between March 2021 and January 2022. A dedicated catheter with five splines delivering bipolar energy with a voltage of 1.8-2.0 kV was used. Arrhythmia recurrence was defined as documented AF/atrial tachycardia (AT) lasting more than 30 seconds after a 90 days blanking period (BP). Procedural and demographic data were analysed. Results 231 patients (42% female, age 69±12, 55% paroxysmal atrial fibrillation [PAF]) were included in this preliminary analysis. 901 pulmonary veins (PV) were identified, and all PVs could be isolated using solely the PFA device. 895 (99.3 %) PVs were isolated with the first application. 32±4 applications per patient were delivered. The overall complication rate was 3.5% (vascular access complication: 2.2%, stroke: 0.9%, tamponade: 0.4%). Median follow-up time was 323 days. 22% of patients experienced a recurrence during the BP after a median of 23 days. Kaplan Meier estimated freedom of AF/AT out of the BP was 75% at one year, 83% for PAF and 64% for persistent atrial fibrillation (persAF, p< 0.0036). In a multivariate analysis blanking recurrence (p<0.001) and female sex (p=0.002) were the only independent predictors for late recurrence. Conclusions This study indicates high acute efficacy of PFA based PVI. 75% of patients are free of AF at one year. Blanking recurrence is an independent predictor for late recurrence after PFA-PVI: further studies are required to better define the duration of the BP after PFA PVI.

Dependence of the Inverse Spin Hall Voltage in Py/Ta Microstrip Array on the Microstrip Width

Since inverse spin Hall effect (ISHE) can transform microwave energy into direct current (DC) energy in ferromagnetic (FM)/nonmagnetic (NM) bilayer metal materials, the ISHE-based FM/NM microstrip arrays have clear potential to be used for microwave power transmission and harvesting. Driven by the need for the miniaturization of electronic devices, it is essential to study the dependence of the characteristics of FM/NM microstrip arrays on their geometries. In this work, we have experimentally demonstrated that the Py/Ta microstrip array’s ISHE signal increases linearly with an increase in the Py/Ta microstrip width and that the effective saturation magnetization of the Py film shows the same change tendency. Moreover, the anisotropy field of the Py film increases linearly as the width decreases. Our work provides a valuable reference for the future miniaturization of ISHE-based rectifier devices.