Instantaneous Power Research Articles

A bubble energy generator featuring lubricant-impregnated surface with high durability and efficiency

Harvesting bubble energy emerges as a potential sustainable solution to harness tremendous marine energy sources. Yet, current bubble energy generators are susceptible to unstable performance owing to the degradation of the physiochemical properties of surface materials under the harsh underwater environment such as surface fouling and wetting transition. Here, we report the design of bubble energy generators featuring the cooperative integration of a slippery lubricant-impregnated porous surface and transistor-inspired architecture, referred to as SLIPS-TBG, that can generate electricity from moving bubbles with high stability in submerged conditions. In this design, the slippery and configurable lubricant layer serves as not only a smooth and mechanically stable surface for bubble transport but also a protective layer preventing the underlying solid materials from direct contact with the external harsh environment. Together with the transistor-inspired architecture, the SLIPS-TBG can deliver a stable electric output of 26.4 V, an instantaneous peak power density of 58.6 W m-3 from continuous bubble impingement in water media, even in extreme conditions involving mechanical abrasion and corrosion. We envision such a design represents a significant step toward real-life applications for bubble-based energy harvesting.

Comparison of APF and STATCOM for Current Harmonic Mitigation

The application of solid-state electronic devices has recorded a geometric increase in the last decade. Devices such as battery charging systems, inverters, switch mode power supplies and a host of electronic-based devices referred to as non-linear loads distort the source signal (particularly the current). Harmonics distortion imposes a severe impact on the well-being of the power system. They cause excessive device heating, reduced performance efficiency, early insulation failure, decreased dynamic torque in rotating systems, etc. This paper bases a study on Active Power Filter (APF) and Static Synchronous Compensator (STATCOM) for mitigation of these distortive harmonics in a system of 3-phase 11kV/400V, 400kVA feeding a system of non-linear loads. The study is based on the IEEE519 standard limits for current harmonics measured at the PCC. Therefore, the system short circuit ratio (SCR) is first determined. Using synchronous reference frame and instantaneous reactive power theories, the APF and STATCOM are respectively designed and run using MATLAB/Simulink software. The result analysis is obtained from the FFT signal processing toolbox of the software, and the device’s performances are evaluated based on the set standard. Results from the FFT spectra showed that the model system contains a considerable number of harmonics before filtering. However, when these devices are connected to the system, all higher-order harmonics have been minimized to the least fractions with respect to the standard, with STATCOM giving a comparatively better performance.

Accounting for a positive, negative and zero sequences power in a three-phase unbalanced electrical system

Purpose. Based on the instantaneous electrical power of a three-phase asymmetric system of sinusoidal periodic current, to determine positive, negative, zero-sequences active and reactive power, as well as invariance power factor. Methodology. In the unbalance case in three-phase electrical system, the electrical energy quality is evaluated by means on voltage and current positive, negative, zero-sequences. At the same time, similar components of active and reactive power have not received practical distribution. But it is precisely in terms of power that electricity is accounted for. The instantaneous power orthogonal components in the time domain are determined using the symmetrical components of voltage and current. Active, reactive powers of positive, negative and zero-sequences are allocated. The result obtained has the property of representativeness, which most of the known results lack. Findings. The three-phase system’s instantaneous power components are analytically determined, including the amplitudes of the oscillating power components. The need to take into account the oscillating instantaneous power components has been proven by means of a graphical interpretation of a special case of the three-phase system mode. As an integral indicator that takes into account the oscillating components of the three-phase system instantaneous power, its root-mean-square value over the repetition period is used. Originality. By calculating the transformer efficiency of the studied model according to the active power positive sequence and the same indicator according to the active power as a whole, it was established, that the component sequence separation affects the results of calculating the generalized indicators, including the power transmission system objects. This can lead to erroneous judgments about the efficiency of the specified facilities functioning. Practical value. The invariance power factor was used to characterize the electrical energy quality level of a three-phase sinusoidal current system in an unbalanced mode.

Modelling, Simulation and Implementation on dSpace 1103 of the Direct Power Control in a Three-Phase Shunt Active Power Filter System

This article describes a control method called "direct power control" designed specifically for parallel active power filters. The purpose of this method is to attenuate harmonics in the supply current and offset reactive power problems. The main goal is to bring the active power and reactive power back to the reference values through hysteresis control. The output of the hysteresis controller is combined with the switching table to regulate active and reactive power in real time by determining the optimal switching configuration of the inverter. This study proposes a novel switching table design based on analyzing the impact of the inverter switching vector on the instantaneous reactive and active power derivatives. The goal is to reduce the number of commutations by eliminating zero vectors while maintaining the required DC bus voltage using anti-windup techniques based on PI controllers.

Triboelectric nanogenerator-integrated symmetric supercapacitor based on TiO2 encrusted MXene nanosheets for energy harvesting and storage applications

With the rapid advances in the Internet of Things, it is possible to construct a self-charging power system integrating a triboelectric nanogenerator (TENG) and supercapacitor (SC), which represents an excellent tool for simultaneous conversion and storage of distributed environmental energy. In particular, the well-researched Ti3C2T x MXene materials for triboelectric nanogeneration lack high and stable power density, mainly due to the charge dissipation effect on their surface. Herein, the effectiveness of MXenes is enhanced by encrusting TiO2 on the inner and outer surfaces via a hydrothermal method. TiO2, which has inherent dielectric properties, could serve the dual function of electron trapping/blocking and surface polarization, mitigating the diffusion and drifting of surficial tribo-charges and thus increasing output TENG performance. An integrated TENG based on MXene/TiO2 composites with a TiO2 concentration of 3 mM has a higher output voltage than a pristine MXene-based TENG (110 V, a 1.83-fold increase) and achieves a maximum instantaneous power density of ∼1440 mW m−2. TiO2 is also conductive to pseudo-faradaic reactions, and the integrated MXene/TiO2 based symmetric SC exhibits an enhanced specific capacitance of 231.08 F g−1 at 1 A g−1, which is 4.52 times that of pristine MXene, with a maximum energy density of 12.74 W h kg−1 at a power density of 483.06 W kg−1. Finally, utilizing polyimide sheets as substrates, the flexible self-charging power system was integrated: the TENG charges the SC up to 0.8 V with a charging/discharging time of 37 s/40 s, showing great promise for the demands of flexible and self-powered electronics.

High powered output flexible aerogel triboelectric nanogenerator under ultrahigh temperature condition

Triboelectric nanogenerators (TENGs) have emerged as promising devices for harvesting low-frequency energy, but its application in high-temperature environments is limited. In this article, a flexible high-temperature resistant fiber substrate material was developed using needled felt and silicon aerogel. This material demonstrated exceptional resistance, withstanding exposure to a butane flame at approximately 1300 ℃ for a minimum of 10 min without experiencing burn-through. Following the application of electrodes and protective encapsulating, a high-temperature resistant silicon aerogel and fiber felts based triboelectric nanogenerator (HTFs-TENG) was successfully created. In addition, we achieved remarkable enhancements in the electrical output performance of the HTFs-TENG by precisely regulating its dielectric properties, resulting in an impressive increase in peak voltage from 17 V to 135 V. The current output increased from 1.4 μA to 6 μA. The HTFs-TENG demonstrated remarkable adaptability, operating effectively at temperatures as high as 275 ℃ and as low as approximately − 75 ℃. Moreover, it showcased an instantaneous power density output of 31.9 mW/m2 under a 100 MΩ resistance load. The HTFs-TENG displayed impressive electrical signal response capabilities at ultralow frequencies (≤1 Hz) across various temperatures and frequencies, positioning it as an ideal self-powered vibration sensor and temperature sensor for diverse generator applications.

Predictive direct control strategy of unified power quality conditioner based on power angle control

The unified power quality conditioner (UPQC), based on power angle control (PAC), addresses the power distribution issue and enhances equipment utilization between two active power filters (APF) of UPQC by employing conventional linear control algorithms that have complex control structures and exhibit challenges in adjusting controller parameters and control delays. This study proposes a UPQC predictive direct control strategy based on power angle control (PDCS-PAC). We combine the direct control strategy with the finite control set model predictive control (FCS-MPC) to establish the UPQC finite set model predictive direct control system model in the dq coordinate system. This approach simplifies the controller structure and alleviates the control algorithm’s complexity. Based on a detailed analysis of the PAC mechanism, an instantaneous power angle determination method is proposed based on the reactive power equalization technique, and a predictive direct control strategy given the current generation mechanism is constructed for the series and shunt sides of the UPQC, considering the active power balance of the UPQC system and the principle of constant load fundamental voltage amplitude. Finally, we construct a simulation platform and a laboratory prototype to validate the feasibility and efficacy of the proposed control strategy.

Organisation of the Structure and Functioning of Self-Sufficient Distributed Power Generation

During the operation of solar and wind power plants, it is necessary to solve issues related to the guaranteed capacity of these plants, as well as the frequency stabilisation in the power system where they operate, and maintain an operating mode of self-sufficiency conditions. One of the solutions to these problems is the use of energy storage systems. This article proposes a mathematical model for the study of frequency and power regulation processes in power systems with distributed generation, which includes renewable energy resources and energy storage systems. The novelty of the model lies in the possibility of determining energy cost indicators based on instantaneous energy power data. The model allows us to estimate the conditions under which distributed generation becomes self-sufficient. The results of the model calculations of two variants of power system operation, which includes wind generators with a capacity of 1500 MW, demonstrate the ability of the proposed model to accurately reproduce the dynamics of the frequency stabilisation process. The calculation results of the energy-economic indicators of a real power system combined with a powerful subsystem of wind generation and a battery-type energy storage system prove the competitiveness of self-sufficient renewable energy power plants.

Investigation of nonlinear magnetic stiffness based thin-layer stacked piezoelectric generators with a force-amplification structure

This paper investigates a nonlinear piezoelectric stack energy harvester incorporating a magnetic spring (NPEH) that utilizes impact-induced frequency modulation to augment the harvested power. The proposed configuration comprises a force amplifier, a piezoelectric stack, a spring-mass system, and a limiter. We formulate a two-degree-of-freedom (2DoF) theoretical model that accounts for the nonlinear characteristics of the system and corroborate it with experimental data. We examine the effects of system parameters on the output performance of the NPEH and demonstrate that the nonlinear magnetic spring facilitates a wideband energy harvesting. For instance, when the surface magnetic field intensities of the upper and lower magnets are 156 mT and 256 mT, respectively, the operational bandwidth reaches 5.23 Hz, which is 154 % greater than that of a linear spring system. Additionally, the nonlinear magnetic spring mitigates the voltage decay during the collision period due to its hysteresis response, thereby increasing the average power. At an excitation frequency of 9 Hz and with surface field strengths of the upper and lower magnets set at 156 mT and 256 mT respectively, the NPEH generates an RMS power of 2.2 mW (with an instantaneous power peak of 1.20 W). We provide design guidelines for optimizing the energy harvesting performance based on the parametric analysis.

Hybrid Energy Generation System with Brushless Generators

Important technical and financial hurdles exist when attempting to extend the power system to remote areas. Decentralized power generation utilising renewable energy sources (RES) has been promoted and is being further investigated as a result. This project showcases a microgrid architecture that uses brushless generators and a single voltage source converter (VSC). Wind and solar photovoltaic arrays are two of the renewable energy sources that power the microgrid system. But to keep the system reliable, there is also a battery energy storage system (BESS) and a diesel generator set. The simplified control and decreased number of switching devices are two benefits of the suggested architecture. In the current architecture, DG is configured as an AC source. The DC connection of the VSC is connected to the wind generator and the solar PV array, both of which are DC sources. Additionally, the BESS is utilised at the DC connection to assist with the dynamic instantaneous power balancing. In addition to integrating systems, VSCs may reduce power quality issues including harmonic currents, imbalance loads, and regulate voltage. To showcase all the aspects of the proposed system, we offer a diverse range of matlab/simulink simulation results.

Triboelectric nanogenerator as next generation traffic monitoring system: Concept and modelling

Rapid development of intelligent transportation demands accurate methods for monitoring vehicle overload information. This paper reports a detail analysis on the viability of triboelectric nanogenerator (TENG) as a smart traffic monitoring system. PVDF and silk film were exploited for TENG fabrication for their strong penchant of gaining and loosing electrons. The objective of this paper is two fold. Initially the electrical performance of the fabricated prototype was measured and reported. The prototype exhibited a maximum open circuit voltage of 648 V and an instantaneous power density of 24 mW/mm2. It was also capable to light up 75 commercial green LEDs. Furthermore, a TENG based traffic monitoring system was introduced for monitoring the traffic overload information and for counting the number of vehicles rolled on it. The TENG was used to convert the mechanical energy from the rolling of vehicles into electric pulses. The pulses that were generated by the TENG was incorporated into an interfacing circuit to anticipate the number of vehicles passed by it. The amplitude of those pulses also give a valuable information regarding the weight of vehicles as the generated voltage is proportional to the input force. Different output voltages of 207 V, 367 V and 558 V were produced for different types of vehicles like bicycle, motorbike and four wheeler passenger vehicle respectively depending on their mass. Output voltage was also varied depending on the load carried by vehicles and showed an increasing trend with load. In consequence, the proposed system can substantially be implemented at various automotive toll plazas to corroborate the paid tax and the actual tax that is supposed to be paid on the basis of laden weight of the vehicle.

Nature‐Driven Edible Black Soldier Fly (BSF) Insect Larvae Derived Chitin Biofilm for Sustainable Multifunctional Energy Harvesting

AbstractWith the increasing demand for portable electronic devices and the shortage of conventional energy resources, energy harvesting from natural resources has gained much attention. Herein, they proposed a black soldier fly (BSF) derived chitin biofilm to fabricate high‐performance triboelectric and piezoelectric nanogenerators. The physiochemical characterizations of the chitin biofilm are demonstrated by the presence of the hydroxyl group, alpha chitin, and beta chitin, which are responsible for the remarkable tribopositive, and piezoelectric function of the chitin derived from BSF. The electrical performance of the proposed work, such as voltage, current, and instantaneous power from BSF/PTFE‐based triboelectric nanogenerator (TENG) are exhibited at 121 V, 15 µA, and 217.8 µW, respectively. Ag/BSF/Ag piezoelectric nanogenerator (PENG) is generated 18 V voltage, 2.2 µA current, and 5 µW instantaneous power. Moreover, the proposed TENG and PENG devices demonstrate the ability to charge the dielectric capacitors and drive low‐power electronic devices like LEDs and a calculator. The proposed results suggested that chitin is a superior biomaterial for developing sustainable energy harvesting devices.

Design of Online Intelligent Detection System for Power Quality and Fault Identification in Distribution Networks

Abstract This paper lays the foundation for the subsequent analysis of power quality in distribution networks by briefly describing the indicators of power quality. Utilizing the zero sequence voltage mutation detection fault of a small current routing algorithm, the instantaneous values of voltage and current of each phase of the three-phase circuit are quickly calculated based on the electrical parameters of instantaneous reactive power and the online intelligent detection system is established. The effectiveness and feasibility of the designed detection system and detection algorithm in detecting electrical energy parameters have been verified through experiments. The results show that the error of voltage measurement is within 0.0003-0.002, the frequency error of the system is up to 0.0117%, the measurement error of three-phase unbalance is distributed between 0.001 and 0.1, and the error of negative sequence and zero sequence is between ±0.003, which meet the system design requirements. It shows that the use of online intelligent detection systems can improve the quality of distribution network operation and fault identification accuracy, improve power quality, and effectively improve the reliability of power supply.

Recyclable waste derived green triboelectric nanogenerator for Self-Powered synthesis of Defect-Free graphene via Mechano-Electrochemical exfoliation

With an upsurge in global waste generation per capita, and energy consumption, there is a simultaneous need for new strategies that can reuse plastic waste and harvest energy for practical applications. Hence, we propose a green triboelectric nanogenerator derived from waste (W-TENG), which was used to demonstrate a novel self-powered application of mechano-electrochemical exfoliation process for graphene synthesis. The W-TENG comprised of discarded plastic banner as tribo-negative material and chocolate wrapper as tribo-positive material, which were confirmed to be polyvinyl chloride (PVC) and aluminium, respectively by using different characterization techniques. The as-fabricated W-TENG exhibited an output VOC of 35 V and ISC of 0.4 µA. The instantaneous power output of the W-TENG was calculated as 0.0217 W/m2 at 45 MΩ external resistance load. The force-dependency behaviour of W-TENG demonstrated that the voltage and current output increased from 20 V to 58 V, and 0.2 to 0.4 µA, upon changing the applied force from 9 N to 30 N. Further, we have demonstrated a novel application, wherein 2D graphene nanosheets were synthesized via mechano-electrochemical exfoliation under highly conductive acidic solution, powered by the W-TENG. Various physico-chemical characterization techniques confirmed it to be defect free few-layered graphene. This work demonstrates a promising “waste to wealth” strategy of using discarded plastic waste to develop a robust mechanical energy harvester to power various applications.

Deterministic power management strategy for fast charging station with integrated energy storage system

With the increasing expansion of fast-charging stations (FCS) and the emergence of high-power electric vehicles (EVs), the development of management strategies to address potential grid disturbances becomes necessary. In this context, this paper proposes an optimized power management strategy for an FCS with integrated battery energy storage systems (BESS). The proposed strategy aims to monitor the variation in AC voltage at the point of common coupling (PCC) and the state of charge (SOC) of the BESS, with the objective of establishing a deterministic formulation to find the optimal instantaneous BESS power level. Therefore, by using the proposed approach, it is possible to compensate for potential fluctuations in AC voltage while maintaining the BESS SOC at appropriate levels. The results are obtained through a real-time hardware-in-the-loop (HIL) platform to verify the system behavior under distinct parameters or operating conditions. These results demonstrate the control flexibility by prioritizing the AC voltage regulation or the BESS charging. Furthermore, the impact of the proposed power management strategy is investigated by performing a comparison with the system without BESS integration. It is observed that the proposed control strategy effectively regulates the PCC voltage and maintains it within acceptable limits.

The voltage feedforward based pulse width modulation strategy under the fluctuated dc‐link voltage for a unidirectional five‐level ac motor drive system with open‐end winding connection

SummaryIn a unidirectional five‐level ac motor drive system with open‐end winding connection, because of the variation of operating frequency of ac motor, the instantaneous power fluctuation of rectifier stage and inverter stage will generate larger voltage ripple on each phase dc‐link capacitors, and further lead to a large amount of current harmonics in output currents of inverter. To cope with this problem, an improved space vector pulse width modulation (SVPWM) strategy based on dc‐link voltage feedforward is proposed. In this paper, the effects of zero sequence current harmonics caused by dc‐link voltage ripple on ac motor are firstly analyzed, including the stator winding flux linkage equation, voltage equation, and electromagnetic torque. Then, the generating mechanism of dc‐link voltage ripple and the current harmonics are discussed in detail in terms of instantaneous power fluctuation of each single‐phase converter. Based on this, an improved SVPWM strategy by modifying the modulation signal is proposed to suppress the generation of current harmonics. Finally, a 2.2 kW prototype experimental results are given, which verify the feasibility and advancement of the proposed modulation strategy.

Role of the deviation motion on the aerodynamic performance of a mosquito wing in hover

The deviation angles during wing flapping motions are generally small for many insects and are known to have insignificant or even detrimental effects on the flight performance. Unlike many other insects, a mosquito hovers with a small sweeping amplitude but relatively large deviation angles. Thus, we investigate the effect of a deviation motion (‘figure-eight’ motion measured by Bomphrey et al. (2017)) on the aerodynamic performance of a mosquito wing in hover by comparing it with that without deviation motion (called in-plane motion). During the stroke, the deviation motion greatly changes the angle of attack and wing moving direction with respect to the stroke plane, but little changes the wing speed. These changes by the deviation motion significantly influence the instantaneous force and power generation. In particular, with the deviation motion, a large drag force is generated at early phase of the downstroke due to the increased angle of attack, and contributes to the vertical force generation. As results, the time-averaged vertical force is increased by the deviation motion, while the time-averaged power required is only slightly increased. Therefore, the mosquito wing generates a larger vertical force more efficiently with the deviation motion, suggesting that a deviation motion may be beneficial for an insect flight with a small sweeping amplitude.

Adaptive power-sharing strategy in hybrid AC/DC microgrid for enhancing voltage and frequency regulation

This paper introduces a new adaptive control strategy for power-sharing in a hybrid AC/DC microgrid (HMG). The existing interlink converter (ILC) control methods exhibit limitations under heavy load and contingency conditions. To overcome this limitation, a bidirectional control strategy is proposed for the ILC, which effectively coordinates battery energy storage systems (BESSs) in both sub-grids while mitigating stress on the ILC and BESSs. The control strategy utilises the state of charge (SoC) and instantaneous power of the BESSs to stabilise frequency and DC voltage on the AC and DC sub-grids, respectively, enabling autonomous operation and plug-and-play capability. Stability analysis employing root locus and a stress level relaxation index for BESSs are presented. Performance evaluation based on the moving mean square error criterion validates the effectiveness of the control strategy. Simulation results using MATLAB/SIMULINK demonstrate the superior performance of the proposed strategy in regulating both voltage and frequency within the system over the existing control approaches. Furthermore, the proposed approach significantly reduces stress levels on the BESSs in different operation conditions.

Transformation of rust iron into a sustainable product for applications in the electronic, energy, biomedical, and environment fields: Towards a multitasking approach

Utilization of waste material for value-added applications is a sustainable approach towards reduction of global waste. Herein, the waste rust iron is transformed into useful Fe2O3 nanoparticles (FNPs). Here for the first time, FNPs were uniquely utilized in multiple applications, including resistive switching (RS), tribo and piezo-electric nano-generators, magnetic hyperthermia, and toxic dyes adsorption from water. The RS characteristics of the Ag/FNPs/ITO device emphasized bipolar switching with excellent cyclic stability, endurance, and memory retention. Afterward, the FNPs based tribo and piezo-electric nanogenerator device demonstrated greater instantaneous power (5200 µW) at 10 MΩ, surpassing previously reported inorganic or garbage materials. Furthermore, the pertinency of FNPs was explored for biomedical application by induction heating studies for magnetic fluid hyperthermia (MFH). MFH revealed an increase in temperature of 14.9 °C and 23.4 °C for 5 mg and 10 mg FNPs ferrofluid, respectively, thus indicating the potential of FNPs for possible cancer treatment with biocompatibility suggestions. Finally, the adsorption study reveals that the FNPs are a promising candidate for the adsorption of safranin M.S., methylene blue, malachite green, and lemon yellow powder, (77, 78, 59, and 56 mg/g, respectively). We believe that our current study will result in a significant impact to reduce the future burden of global waste and thus encourage its utilization for value-added applications.

Investigation of the piezoelectric performance of P(VDF-TrFE)/SnO2NPs/GR composite film fabricated via electrospinning

ABSTRACT This paper introduces an innovative sandwich-structured piezoelectric nanogenerator film. In contrast to conventional piezoelectric generators, it exhibits enhanced flexibility and generates higher voltage. It can function as a self-sustaining power source for wearable sensors. To augment the film’s β-phase content, consequently boosting the nanogenerator’s voltage output, the nanofilm was manufactured through high-voltage electrospinning in poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), incorporating stannic oxide nanoparticles (SnO2NPS) and graphene (GR).The relationship between the surface morphology, β-phase content, and voltage output performance of composite piezoelectric films with distinct compositions was comprehensively assessed and scrutinized utilizing scanning electron microscopy (SEM), X-ray diffraction (XRD) patterns, and vibration platforms. The findings reveal that the composition of 12% P(VDF-TrFE) + 5% SnO2NPS + 0.1% GR yields the finest fiber alignment, the highest β-phase content, as well as peak open-circuit voltage and short-circuit peak current values of 22.43 V and 12.95 μA, respectively. This signifies a 1.5-fold and 1.3-fold improvement compared to the film containing only SnO2NPS, and a 2.43-fold and 1.92-fold enhancement relative to the pure P(VDF-TrFE) film. Consequently, it achieves a maximum instantaneous output power of 64.578 μW. Securing the nanogenerator with the aforementioned composition to the sole of a shoe and running for 21 minutes can charge the capacitor to 4 V, thereby empowering it to operate commercial liquid crystal thermometers or approximately 80 LED lights for approximately 1.6 seconds. This technology possesses substantial significance within the realm of self-sustaining low-power electronic devices.