Conventional Power Supply Research Articles

Enhanced Coil Design for Inductive Power-Transfer-Based Power Supply in Medium-Voltage Direct Current Sensors

This paper presents an integrated coil design method for inductive power-transfer (IPT) systems. Because a medium-voltage direct current (MVDC) distribution network transmits power at relatively high voltages (typically in the tens of kV), accurate fault diagnosis using high-performance sensors is crucial to improve the safety of MVDC distribution networks. With the increasing power consumption of high-performance sensors, conventional power supplies using optical converters with 5 W-class output characteristics face limitations in achieving the rated output power. Therefore, this paper proposes a safe and reliable power supply method using the principle of IPT to securely maintain the insulation distance between the distribution network and the current sensor-supply line. A 100 W prototype IPT system is investigated, and its feasibility is validated by comparing its performance with conventional optical converters.

Sustainable in-situ steam injection approach for shale oil extraction in Xinjiang, China: A technical and economic analysis

This work proposes a microgrid system for in-situ steam heating extraction of oil shale utilizing renewable energy sources. This system is designed for high efficiency and promises significant cost savings. This work couples the underground in-situ steam injection heating model and the microgrid system model to analyze the system's energy-saving and economics. Due to the technical and economic importance of Xinjiang oil shale in Northwest China, it is chosen as a case study to investigate the feasibility of the proposed method. The effect of steam temperature, pressure, and renewable resources at the oil shale extraction location on the economics of the system is examined. The results show that using renewable energy power is superior to hybrid and conventional power supply methods in terms of economy and energy efficiency. Moreover, renewable energy resulted in a 12.38 % reduction in the total net present cost (NPC) when the steam temperature increased by 40 °C. The total NPC of the project can be reduced by 28.61 % when the pressure of superheated steam is decreased by 4.0 MPa. The results indicate that the solar resource at the oil shale extraction location significantly impacts the system's economics. The study provides a theoretical basis for the economic analysis of oil shale steam injection extraction technology.

Recent Advances in Flexible Self-Powered Sensors in Piezoelectric, Triboelectric, and Pyroelectric Fields

The rise of the Internet of things has catalyzed extensive research in the realm of flexible wearable sensors. In comparison with conventional sensor power supply methods that are reliant on external sources, self-powered sensors offer notable advantages in wearable comfort, device structure, and functional expansion. The energy-harvesting modes dominated by piezoelectric nanogenerators (PENGs), triboelectric nanogenerators (TENGs), and pyroelectric nanogenerators (PyENGs) create more possibilities for flexible self-powered sensors. This paper meticulously examines the progress in flexible self-powered devices harnessing TENG, PENG, and PyENG technologies and highlights the evolution of these sensors concerning the material selection, pioneering manufacturing techniques, and device architecture. It also focuses on the research progress of sensors with composite power generation modes. By amalgamating pivotal discoveries and emerging trends, this review not only furnishes a comprehensive portrayal of the present landscape but also accentuates avenues for future research and the application of flexible self-powered sensor technology.

Optically powered FiWi system for B5G hybrid VLC/RF access networks.

This paper proposes the concept and reports the demonstrator of an optically powered fiber/wireless (FiWi) system based on a hybrid visible light communication (VLC) and RF access network for beyond 5G(B5G) indoor applications. The power-over-fiber (PoF) technology is properly applied to simultaneously energize two components from the remote site, namely: a radio-over-fiber (RoF) module, which contains a photodetector and an RF amplifier; a red laser from the VLC system. The proposed PoF system is composed of a 500 m conventional multimode optical fiber (MMF) with a 62.5 μm core diameter, which enables the transmission of up to 12 W optical power with a power transmission efficiency (PTE) of 14%. In the proof of concept, 8.1W optical power is generated to feed the 5G system components. Regarding the communication setup, a 5G new radio (5GNR) signal is initially transported through a RoF fronthaul, composed of 10 km of single-mode fiber (SMF), followed by the hybrid VLC/RF access network. The performance investigation of the B5G communication system is based on an analysis of the root mean square error vector magnitude (EVMRMS) parameter. Experimental results indicate 1.2Gbps throughput in the VLC link using a 200MHz bandwidth and 64-quadrature amplitude modulation (64-QAM), resulting in approximately 4.02% of EVMRMS. Moreover, the RF link at 3.5GHz provides 360 Mbps with an EVMRMS of 2.67%. Finally, a comparison between the PoF system and conventional power supply validates the proposed approach's applicability for B5G wireless communications.

Power-over-fiber-based optical wireless communication systems towards 6G

This paper reports two implementations of power-over-fiber (PoF) solutions applied to radio-over-fiber (RoF) and optical wireless communication (OWC) systems, in the context of an industrial environment. We employ a conventional 62.5-µm multimode fiber (MMF) to deliver optical power to different communication links based on RoF, free-space optics (FSO), and visible light communication (VLC) technologies aiming beyond 5G (B5G) and 6G applications. First, a 3.5-GHz 5G New Radio (5G NR) signal is transmitted throughout a 20-km single-mode optical fiber (SMF) link using RoF technology. Regarding the PoF system, a 5-W optical power is transmitted through a 100-m MMF link. A photovoltaic power converter (PPC) and a DC/DC converter are employed to convert the power from the optical to the electrical domain and adjust the voltage level, respectively, with the purpose of energizing a remote RoF module. The attainable optical and electrical power transmission efficiencies (OPTE and PTE) are 80% and 19%, respectively. Posterior, a second PoF system is implemented to power a hybrid RoF/FSO/VLC B5G system, comprising a 200-m MMF and an additional DC/DC converter. Over 10.5 W of optical power is transmitted to feed an electrical amplifier (EA) and a white LED from the VLC link. In this configuration, we achieve 78% and 18.5% of OPTE and PTE, respectively. Furthermore, a performance investigation based on the root mean square error vector magnitude (EVMRMS) metric is conducted to evaluate the signal using the implemented PoF systems and a conventional electrical power supply. In the first implementation, a throughput of 600 Mbps is achieved with 100-MHz bandwidth without performance degradation, when compared to the conventional-powered RoF system, whereas, in the second implementation, 60-Mbps throughput is achieved when employing the FSO and VLC technologies simultaneously, demonstrating the applicability and potential of the PoF technique for B5G and 6G industrial communications.

A wind-driven rotating micro-hybrid nanogenerator for powering environmental monitoring devices based on a brush-type triboelectric unit

Abstract The rapid rise of the IoT (Internet of Things) technology and microelectronics technology has promoted the development of sensors to ultra-low power consumption. However, for conventional wired power supply and chemical battery power supply, there are difficulties in wiring, inconvenient battery replacement and environmental pollution problems, so there is an urgent need for a green power supply. The low cost and simple structure of TENG (Triboelectric nanogenerator) have attracted much attention from researchers. However, for most of the existing TENG, there are some problems such as narrow operating frequency range, short life of TENG, insufficient traditional flexible friction contact, and serious wear of rigid friction contact. Herein, we propose a rotary brush-type triboelectric-electromagnetic hybrid nanogenerator. Through the experimental tests, the TENG part can output the maximum power of 0.88 mW under the external load of 8 MΩ at 400 rpm (wind speed of about 8.3 m/s). The EMG (Electromagnetic Generator) part can output the maximum power of 15.5 mW under external load of 360 Ω. The LED lighting test proves that the generator broadens the frequency of energy harvesting. In the capacitor charging test, the high voltage characteristics of tribological power generation play the advantages of continuous voltage boost, and the high current characteristics of electromagnetic power generation play the advantages of high power. The hybrid nanogenerator can realize the wind energy harvesting under the broadband wind speed of 3 m/s~14 m/s. At a wind speed of 5.6 m/s, the hybrid nanogenerator ran at about 225 rpm and successfully powered the anemometer after 21 s. After 80,000 cycles, the maximum open circuit voltage only drops by 5.6%, which proves that the rotary TENG unit has a long generation life, and can realize the harvesting of wind energy and the power supply of wind speed sensor.

Accelerating wound healing with flexible zinc ion microbatteries coupled with endogenous electrical fields

Wound healing is an important physiological process in living organisms, involving the migration and proliferation of cells in the endogenous electric field (EEF). Continuous and stable electrical stimulation by an external power supply can effectively mimic the EEF, accelerating the biological processes involved in wound healing. However, the clumsiness of conventional external power supplies and the unstable voltage output of novel power supplies greatly limit the application of electric fields for wound healing. Here we demonstrate the use of a flexible and wearable microbattery for wound healing. The annular electrode is designed to generate an annular electric field in the same direction as the EEF of the wound, allowing for faster, more uniform fibroblast migration, proliferation, and transdifferentiation processes, thus accelerating wound healing. Studies on rats show that skin wounds given a stable electric field using aqueous Zn-MnO2 microbatteries with an operating voltage of 1.5 V healed completely within 6 days, while the blank control group took 10 days or longer. Further, the series connection of microbatteries can match wounds of different areas, enabling rapid healing. These advantages make flexible microbatteries highly promising for practical applications in the biomedical field.

Multi‐timescale synergistic planning for flexible regulation of thermal power to support wind‐photovoltaic‐storage

AbstractWith the proposed goal of 30•60 carbon peak and carbon neutrality, the proportion of new energy continues to increase, the proportion of conventional power supply capacity continues to decrease, and the flexibility demand of the existing power system continues to increase and the flexibility adjustment ability is insufficient. Therefore, a medium and long term planning method is proposed to flexibly adjust the multi‐time scale coordination of thermal power support wind and solar storage. Considering the long‐term investment decision and the short and medium term operation simulation, the flexible transformation cost and the penalty cost of insufficient flexibility of thermal power units are included in the planning objective, and a multi‐time scale coordinated planning model is established with wind power as the main power source and thermal power and hydrogen energy storage as the auxiliary power source. Through the multi‐stage cycle iteration of investment decision model, medium and long term production simulation and typical daily operation simulation, the flexible transformation resources of wind and solar fire storage and thermal power are optimized. Finally, a provincial power grid in northeast China is taken as an example to verify that hydrogen energy storage equipment assisting thermal power unit flexibility transformation can better support load fluctuation and large‐scale new energy access in new power systems.

Experimental Study on No-Load Loss Characteristics of an Alternating Current Excitation Motor

An AC excitation power supply will produce a series of harmonic currents in motors compared to the conventional power supply, increase the time harmonic component, and then generate a harmonic magnetic field; harmonics will cause motor vibrations and noise in the motor and will produce a corresponding additional loss, increasing the motor temperature rise; these key technical problems need to be solved in domestic pumped storage AC excitation motor engineering applications. Herein, the no-load loss characteristic test of a 3 MW alternating current excited motor was mainly carried out using a test prototype of the 3 MW alternating current excitation motor. Further, with the aid of the finite element method, the numerical study of the no-load loss characteristics of a 3 MW alternating current excited motor was performed. The relationship between the key factors such as the no-load characteristics, no-load loss characteristics, and constant loss and voltage per unit value is analyzed, and the variation law of the no-load core loss of motors under different loads is explored. The results demonstrate that, under no-load conditions, when the applied voltage was less than the rated voltage, the voltage was proportional to the current. When the applied voltage was more significant than the rated voltage, the current increased as the voltage increased, but the relationship between the two was no longer proportional. The constant loss of the motor maintained a linear relationship with the square of the unit value of the voltage scale. When the square of the unit value of the voltage scale was zero, the loss was equivalent to the wind friction loss under no load. The core loss increased with the increase in load, and the greater the load, the faster the increase rate of the motor iron loss. The comparison deviation between the test and simulation results was less than 10%. The simulation and experimental results verified the effectiveness of finite element modeling and the finite element calculation method.

2D Material‐Based Wearable Energy Harvesting Textiles: A Review

Wearable electronic textiles (e‐textiles) have emerged as a transformative technology revolutionizing healthcare monitoring and communication by seamlessly integrating with the human body. However, their practical application has been limited by the lack of compatible and sustainable power sources. Various energy sources, including solar, thermal, mechanical, and wind, have been explored for harvesting, leading to diverse energy harvesting technologies, such as photovoltaic, thermoelectric, piezoelectric, and triboelectric systems. Notably, 2D materials have gained significant attention as attractive candidates for energy harvesting and storage in e‐textiles due to their unique properties, such as high surface‐to‐volume ratio, mechanical strength, and electrical conductivity. Textile‐based energy harvesters employing 2D materials offer promising solutions for powering next‐generation smart and wearable devices integrated into clothing. This comprehensive review explores the utilization of 2D materials in textile‐based energy harvesters, covering their preparation, fabrication, and characterization strategies. Recent advancements are highlighted, focusing on the integration of 2D materials and their practical implementations, shedding light on the performance and effectiveness of 2D‐material‐based energy harvesters in e‐textiles, and highlighting their potential as a sustainable alternative to conventional power supplies in wearable technologies.

On-line sample preconcentration by LVSEP-FASI with simple voltage control on Y-channel chips.

To eliminate complicated voltage controls for highly sensitive microchip electrophoresis (MCE) analyses on the basis of combining two online sample preconcentration techniques, large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) and field-amplified sample injection (FASI), cross-channel microchips and a multichannel high-voltage power supply were replaced to Y-channel chips and a conventional power supply designed for capillary electrophoresis, respectively. By simple switching of the electric circuit after the LVSEP-FASI sample enrichments, the focused analytes could be separated during anodic migration in a separation channel. In the LVSEP-FASI analysis of fluorescein using the Y-channel microchip, the maximum sensitivity enhancement factor (SEF) of 7400 was achieved, resulting in a 30-fold detectability increase compared to the conventional LVSEP. The developed method was applied to the oligosaccharide analysis in MCE. As a result, the SEF for maltotriose was improved from 450 to 2300 and the baseline separation of the oligosaccharides was achieved without any complicated voltage control in LVSEP-FASI on the Y-channel chips.

Powering the Future: Hydrogel-based Soft Ionic Conductors Energize Flexible and Wearable Triboelectric Nanogenerators

Powering the Future: Hydrogel-based Soft Ionic Conductors Energize Flexible and Wearable Triboelectric Nanogenerators

Piezoelectric fibers-based PVDF-ZnS-carbon nano onions as a flexible nanogenerator for energy harvesting and self-powered pressure sensing

Herein, an innovative piezoelectric nanogenerator (PENG) is fabricated by electrospun polyvinylidene fluoride (PVDF) and a hybrid nanofiller comprised of zinc sulfide nanorods (ZnS NRs) and carbon nano onion particles (CNOs). From a mechanistic point of view, it has been determined that ZnS nanorods contribute to the alignment of the electric dipoles in PVDF and enhance the overall piezoelectric properties of the composite nanofibers because of their intrinsic piezoelectric ability. CNOs as a family of carbon allotropes with electrical conductivity as well as easy preparation method from natural source of castor oil as a cost-effective preparation method can improve the piezoelectric performance of PVDF nanofibers by positively enhancing the charge transfer rate and thereby enabling the alignment of PVDF’s electric dipoles. The developed PVDF-ZnS-CNOs composite (with 0.15 wt% of CNOs loading) based PENG exhibited improved electrical functionality and stability. The maximum power density of approximately 30.15 μW/cm2, the load resistance of 1.0 MΩ, the open-circuit voltage of 14 V, and the short-circuit current of 35 μA were observed. In addition to evaluate the energy harvesting and sensing capabilities, the constructed PENG was utilized to identify numerous types of human movements, and several capacitors were charged. It was observed that a capacitor with a 1 µF capacity could be charged to 9.5 V under mechanical stimulation in 45 s, which shows a promising platform for eliminating the need for an external power source to operate portable gadgets. Consequently, the developed PENG possess high potential, which can be utilized as an alternative to conventional power supplies in self-powered devices by taking advantage of their flexibility and stability.

Cost cutting approach of distillery effluent treatment using solar photovoltaic cell driven electrocoagulation: Comparison with conventional electrocoagulation

This work is an attempt to treat rice grain-based distillery biodigester effluent (BDE) using photovoltaic (PV) cell driven electrocoagulation (EC) process. The BDE initially contain high chemical oxygen demand (COD) of 4252 mg/l and color of 456 PCU.PV cell-based EC reactors have been used to treat BDE with various electrode combination including FeFe, AlAl, FeAl, and AlFe etc. The effect of different operating parameters such as pH, current density (CD), electrode gap (g) and electrode combination on COD and color removal efficiency were investigated. Maximum COD and color removal efficiency of 94.9 % and 81.3 %, respectively were found at the optimum condition of pH 7, CD 24.9 mA/cm2, g 1.75 cm, electrolysis time (t) 60 min, electrode loss (Ec) 17.1 mg/land electrode combination of FeFe. A comparative study has been made by powering the EC system through conventional power supply and solar PV source and the PV oriented system was found better. Conventional power source required longer; t and needed slightly higher voltage while, PV system needed shorter t and low voltage to achieve nearly same pollution removal efficiency.

A novel high-performance three-phase magnetic field energy harvester for powering up vehicle onboard electronics

The boosting development of vehicle electrification and onboard sensing networks in the intelligent vehicle era poses a significant challenge to conventional electrical power supply systems. This study developed a novel passive three-phase magnetic field energy harvester (TMEH) for reliable and sustaining power to drive vehicle onboard electronics, which recycles the induced magnetic field energy around the power lines of a permanent magnet synchronous motor (PMSM) on an electric vehicle (EV). A Y-Y topological connection pattern for three-phase coils was designed to enhance and stabilize the TMEH output performance. Furthermore, three auto-shift operating modes were assigned to the TMEH to tackle the dynamic changes of the captured power caused by unpredictable vehicle manoeuvres and road conditions. The theoretical model and numerical method were also established for structural optimization of the TMEH, followed by a series of experimental tests for highlighting the impacts of the power lines carrying alternating current on TMEH. The results have indicated that the proposed TMEH showed impressive energy conversion efficiency, providing an independent power supply for sensors and other electronics applications on a 4 kW-PMSM driven EV. Bench testing results and practical EV driving trials demonstrated the capability of the TMEH prototype to power up multiple types of sensors and electronic devices under most EV driving conditions. Specifically, an average power of 5.69 W and power density of 123.85 mW/cm3 were generated by the harvesting coils when excited by a 50 A current at 50 Hz. Furthermore, the maximum TMEH energy conversion efficiency of 41.9% at the excitation current frequency of 50 Hz is obtained in laboratory conditions. In EV driving tests at speeds of 20–30 km/h, the TMEH presented steady output power up to 5.98 W, capable of driving various loads such as an electronic resistor, Li-ion battery, GNSS/INS device, driving recorder, and cellphone, either with the employment of one or two sets of harvesting coils. The approach of this study offers a promising application scenario to power up numerous electronics on a commercial transport EV platform driven by a more powerful PMSM.

Effect of DGs on Power Quality of Distribution System: An Analytical Review

Abstract This article offers an overview of distributed generation (DG) in distribution systems (DS). The primary goal of this study is to assess the performance of DGs in DS. Due to the rise in electrical energy consumption, it is anticipated that DG sources would be essential to DS. Future power generating networks have a bright outlook on consideration of DG’s potential for utilising alternative energy sources. The quality of power systems is a crucial concern for energy providers and consumers. In order to decrease reliance on fossil fuels for the production of electricity, distributed generations are gaining importance in the energy supply networks in many countries. Distributed generators are small units that generate electricity close to customer sites. These DGs use renewable energy methods such as wind energy, solar energy and geothermal energy. The incorporation of DGs into a conventional power supply system evolves in a number of side effects, including an increase in the number of short circuits, higher power losses, a decrease in the quality of the energy produced, voltage transients, problems with voltage stability, coordination issues regarding voltage regulation and protection, the possibility that system protection will not function correctly, and the fact that there is less residual current input as a result of the DG bidirectional power flows. This review paper discusses the impacts of the penetration of DG into DS and provides various strategies to mitigate these effects.

Efficiency and consistency enhancement for alkaline electrolyzers driven by renewable energy sources

Low-cost alkaline water electrolysis from renewable energy sources (RESs) is suitable for large-scale hydrogen production. However, fluctuating RESs lead to poor performance of alkaline water electrolyzers (AWEs) at low loads. Here we explore two urgent performance issues: inefficiency and inconsistency. Through detailed operation process analysis of AWEs and the established equivalent electrical model, we reveal the mechanisms of inefficiency and inconsistency of low-load AWEs are related to the physical structure and electrical characteristics. Furthermore, we propose a multi-mode self-optimization electrolysis converting strategy to improve the efficiency and consistency of AWEs. In particular, compared to a conventional dc power supply, we demonstrate using a lab-scale and large-scale commercially available AWE that the maximum efficiency can be doubled while the operation range of the electrolyzer can be extended from 30–100% to 10–100% of rated load. Our method can be easily generalized and can facilitate hydrogen production from RESs.

Optimization-Driven Machine Learning Approach for the Prediction of Hydrochar Properties from Municipal Solid Waste

Municipal solid waste (MSW) management is an essential element of present-day society. The proper storage and disposal of solid waste is critical to public health, safety, and environmental performance. The direct recovery of MSW into useful energy is a critical task. In addition, the demand for conventional power supplies is high. As a strategy to solve these two problems, the technology to directly convert municipal solid waste into conventional energy to replace fossil fuels has been obtained. The hydrothermal carbonization (HTC) process is a thermochemical conversion process that utilizes heat to convert wet biomass feedstocks into hydrochar. Hydrochar with premium gasoline properties is used for fuel combustion for strength. The properties of fuel hydrochar, including C char (carbon content), HHV (higher heating value), and yield, are mainly based on the properties of the MSW. This study aimed to predict the properties of fuel hydrochar using a machine learning (ML) model. We employed an ensemble support vector machine (E-SVM) as the classifier, which was combined with the slime mode algorithm (SMA) for optimization and developed based on 281 data points. The model was primarily trained and tested on a fusion of three datasets: sewage sludge, leftovers, and cow dung. The proposed ESVM_SMA model achieved an excellent overall performance with an average R2 of 0.94 and RMSE of 2.62.

Analysis of Energy Losses in the Novel Distributed Power Supply System for Trams

The traction substation in conventional power supply systems for trams is a bottleneck of the system. It requires the connection with medium-voltage grid, demands high values of instant power and its centralized topology generates additional energy losses. Since the availability of low-power photovoltaic (PV) generation is increasing in the utility system, we propose to replace conventional substations with a distributed system of low-power devices cooperating with low-voltage grid and PV installations owned by individual households. The proposed in this article distributed power supply system for trams (DPSS-T) consists of multiple traction aggregators (TAs) equipped with energy storage devices (ESDs) which are distributed along the tram line. In order to evaluate the benefits of applying DPSS-T this proposed system was compared with the conventional topology regarding the energy losses in terms of annual operation. Moreover, the following aspects have been studied for the wide range EDS sizes and PV generation: PV energy injection into the power utility system, the utilization of installed ESD, and the contribution of PV generation in energy consumed by traction vehicles. At the same time, the energy management for this new topology has been proposed. The ESDs are charged with relatively low power, between tram runs and discharged with full power during the runs. The suggested energy management eliminates peaks in substation power demand. The obtained results show that despite the fact that the proposed DPSS-T is supplied from low-voltage grid the energy losses are reduced by 58%–69%.

MOPTIC-SM: Sleep mode-enabled multi-optimized intermittent computing for transiently powered systems

The proliferation of Internet of Things (IoT) based devices has led to a significant increase in their usage across a broad range of application areas. However, the replacement and/or periodic maintenance of the billions of conventional power supplies used by these systems is required on an annual basis, which raises serious environmental and economic concerns. To subjugate these issues, transiently-powered embedded systems (TPESs) make use of an ambient energy resource. However, the non-uniform availability of ambient energy results in frequent system reboots. This problem can be mitigated by utilizing state checkpointing in non-volatile memory, yet a high number of checkpoints can lead to excessive energy consumption. In this research, a novel sleep mode-enabled multi-optimized intermittent computing method is proposed that combines data sampling and memoization to reduce the number of checkpoints. The proposed method is validated using the Microchip SAM-L11 embedded platform for the implementation of the Canny Edge Detection (CED) algorithm. The results of the experiments indicate that the proposed method effectively reduces the number of checkpoints for a given application by 50 percent in CED and maintains 70 percent accuracy in comparison to conventional TPES checkpointing. It is believed that the proposed solution will have several exciting applications in both the consumer market and industry.