Instantaneous Power Research Articles

An in-depth oxidation kinetic study of CuCrxMn1-xO2 (x = 0, 0.1, 0.3) for thermochemical energy storage at medium-high temperature

In this study, we investigated the effect of Cr doping on CuMn2O4/CuMnO2 and established an oxidation (heat release) kinetic model for CuCrxMn1-xO2 (x = 0, 0.1, 0.3) as an extension of our previous research on developing medium-high temperature (500–1000 °C) redox-type thermochemical energy storage materials. Our objective is to develop a reliable model for predicting the heat release power at constant temperature conditions. The as-prepared samples were characterized using XRD Rietveld refinement, SEM-EDS, and XPS analysis to obtain a more precise crystal structure and elemental states. The oxidation kinetic model was established using an isothermal oxidation method which differs from the method (non-isothermal) used in the previous study. Additionally, the pressure term was also taken into consideration. The reaction models and kinetic parameters of CuMnO2, CuCr0.1Mn0.9O2 and CuCr0.3Mn0.7O2 were determined using master plots and Arrhenius plots. Among all sample, CuCr0.1Mn0.9O2 exhibited the smallest oxidation activation energy of 29.932 kJ/mol, which was significantly lower than the previous value obtained using the non-isothermal method. Combining the reaction rate and heat release, CuCr0.1Mn0.9O2 showed the highest instantaneous power output of 4.69 kW/kg at the oxygen partial pressure of 0.5.

Hybrid active and passive strategies for chance-constrained bilevel scheduling of community multi-energy system considering demand-side management and consumer psychology

Developing hybrid renewable energy multi-energy system at the community level (CMES) is crucial for sustainable development and society. There are considerable resources in community users that can be activated by demand-side management (DSM) and combined with CMES for smart and clean energy supplies. This work focuses on optimal multi-timescale CMES management at energy and power levels considering source-load interaction. Firstly, the flexible community building and EV loads are comprehensively modeled, including the subjective psychological factors of community users' willingness to participate in DSM activities. Then, a bilevel collaborative strategy is proposed to manage CMES. The upper-level unites all schedulable resources to actively control CMES and flexible loads to achieve optimal multi-energy balances. The lower-level forms hybrid virtual electrical storage to passively adapt to instantaneous power rebound/decline events. These two levels are bridged through chance-constrained programming, achieving risk avoidance. Finally, the performances, including community users, the grid, and CMES itself, are evaluated, as well as influences of confidence level and user attitudes (in DSM activities). Simulation results show that the proposed strategy with a high confidence level avoids the lack of flexibility and load interruption and reduces cost and grid interaction fluctuations by 5.75 % and 59.48 %, respectively. DSM can support the efficient and flexible operation of CMES by providing equivalent energy storage with a capacity/power of up to 657 kWh/350 kW. On the other hand, the high subsidy price reduces CMES's interests, and users' benefits will be weakened accordingly, while users actively involved in DSM create a win-win situation with CMES.

Predictive Current Control for Three-Level Four-Leg Indirect Matrix Converter Under Unbalanced Input Voltage

In this paper, a robustness evaluation of model predictive current control with instantaneous reactive power minimization for a three-level four-leg indirect matrix converter is presented. Unbalanced voltages can be extremely dangerous, especially for motors and other inductive equipment. Unbalanced voltages can have a detrimental effect on equipment and the power system, which is exacerbated by the fact that a small phase voltage imbalance can result in a disproportionately large phase current imbalance. The robustness test is carried out by considering balance and unbalanced input voltages. The proposed control predicts the behavior of the load current and the instantaneous reactive power for every possible 96 switching states. Subsequently, it selects the optimum switching state which fulfils the objectives of the control without the need of modulators. The cost function has been adequately modified to consider the asymmetrical aspect of the input voltage. Experimental validation using a laboratory prototype was conducted by using FPGA under a wide range of input voltage unbalance. The experimental results show high fidelity load current reference tracking while maintaining relatively low instantaneous reactive power during the transient and steady-state condition. The percentage of reactive power after setting the optimal weighting factor, the average reactive power was found to reduce to approximately 10-20%.

Design of Hybrid Power Chassis System Based on Fuzzy Control

For wheeled robots working in environments such as sand and slopes, due to the many ups and downs in the environment, they often encounter working states such as acceleration and climbing. This often requires its power supply to provide instantaneous high power, resulting in a large current discharge of the power supply, which seriously affects its service life. To solve this problem, this paper will use a composite power supply composed of supercapacitors and batteries to supply power to the robot chassis and use fuzzy control to perform closed-loop regulation on the output power of the batteries.

Gigantic and Continuous Output Power in Ionic Thermo-Electrochemical Cells by Using Electrodes with Redox Couples.

The main obstacle of ionic thermo-electrochemical cells (TECs) in continuous power supply lies in a low heat-to-electricity energy conversion efficiency because most TECs work in thermodiffusion mode in which the ions are confined in a liquid/electrolyte media. The introduction of the redox couple onto the electrode surface may overcome the obstacle by resolving the low mass transport rate of ions caused by the redox process occurring near but not on the electrode surface. Herein, the authors demonstrate enhancement of TECs by integrating the redox couple directly onto the electrode surface to maximize the mass transport efficiency. A discontinuous interfacial modification strategy is developed by using a carbon cloth/iron (II/III) phytate as the symmetric electrodes. The gelled electrolyte consisting of a polyacrylamide matrix and phytic acid is shown to promote selective ion diffusion. A synergistic combination consisting of the thermodiffusion effect and redox reactions on the electrode is established in a pre-treated layout. Such TEC affords a high output voltage of 0.4 V, an excellent instantaneous output power density (20.26 mW m-2 K-2 ) and a record-high 2 h output energy density (2451 J m-2 ) under TH = 30 °C with TC = 15 °C, with an ultrahigh Carnot-relative efficiency of 1.12%.

Analytical Modeling of Magnetization Losses in Twisted Stacked HTS Conductors

The European post-ITER fusion demonstrator reactor (DEMO) design activities have been ongoing for several years in the framework of the EUROfusion Consortium. The designs proposed for the DEMOnstration Fusion Power Plants (DEMO) magnets include options based on high-temperature superconducting (HTS) technology, namely as an Insert in the Central Solenoid (CS). This work describes the development of tools for the calculation of magnetisation losses in a twisted-stacked HTS cable, which represents one of the most promising configurations of HTS fusion Cable-in-Conduit conductors (CICC). This geometry cannot be tackled with the straightforward application of 1D or 2D models, given their inability to describe the twisting of the tape stacks. However, the methodology proposed in this work allows one to treat the twisting of the conductors by discretizing them in a set of straight pieces. A set of analytical equations is developed to compute the instantaneous power losses in the slab approximation. This fast, easy-to-use, open-access tool, can be employed for the computation of AC losses in the central solenoid modules of a tokamak. In particular, we have applied the model to study the HTS insert of the DEMO central solenoid.

Output Voltage Drop and Input Current Ripple Suppression for the Pulse Load Power Supply Using Virtual Multiple Quasi-Notch-Filters Impedance

To balance the instantaneous power difference between the pulsed output power and the constant input power of the pulse load power supply (PLPS), an active capacitor converter (ACC), which can compensate the pulsed current, is connected in parallel with the output of the dc-dc converter in the PLPS. In this paper, based on the Fourier decomposition results of the load current, it is evident that square waves have significant harmonic content. Hence, to provide the lower impedance at the frequencies of the high content harmonics in the load current, a virtual impedance that consisted of the multiple quasi-notch-filters (MQNF) is proposed to be in parallel at the port of the ACC for the suppression of output voltage drop and input current ripple. The virtual parallel impedance is implemented by the output voltage feedforward control (FFC) of the ACC. The design considerations of the virtual parallel impedance are presented to ensure the stability of the PLPS. Finally, a synchronous rectifier buck (SR-buck) converter with a bidirectional buck/boost converter is tested at the pulse repetition frequency (PRF) of 100-300 Hz and the pulse duty cycle of 0.15 to verify the validity of the proposed control scheme.

Cross kit reconfiguration algorithm for enhanced output power of PV array during shading mismatch conditions

Maintaining the uniform irradiance in an extensive photovoltaic (PV) system is almost impossible. The mismatch between panels of a PV array results in substantial power loss. The PV panels in an array are reconfigured by the proposed Cross-Kit (CK) technique to obtain optimal power output for different partial shade situations (PSS). The suggested approach allows the structure to balance the shade effect across the entire PV array with different physical places of panels. The PV modules are linked using the Total Cross Tied (TCT) configuration, and the CK technique decides the physical placement of modules within the array. The electrical connections of the TCT-linked PV array are unaffected by the CK panel configurations. The PV array’s output arranged with the suggested CK method is assessed and contrasted with TCT and Odd-Even (OE) reconfiguration for mathematical and experimental validation. Four different PSS are taken into consideration. The percentage instantaneous maximum power improvement compared to TCT and OE ranges from 5.49% to 26.73%. The benefits of the suggested approach include straightforward guidelines for implementation, explanation of the P-V plots, and a reduced charge of maximum power point tracking.

Location of generating units most affecting the angular stability of the power system based on the analysis of instantaneous power waveforms

Location of generating units most affecting the angular stability of the power system based on the analysis of instantaneous power waveforms

A Design and Implementation of a New Control Based on Petri Nets for Three Phase PWM-Rectifier

This article introduces a novel and effective diagram based on direct instantaneous power control (DPC) of a PWM-controlled rectifier connected to the grid without a switching table. An optimum control vector of the PWM rectifier's input voltage, which depends on the switching states determined by a Petri nets controller, is adopted. This approach limits the instantaneous detection errors of reactive and active powers, maintains the DC bus voltage at a reference level, and ensures current close to a sinusoidal wave, guaranteeing operation at a unit power factor. The instantaneous tracking errors of active and reactive powers and the angular position of the voltage are used as input variables for the proposed controller, which then selects the best control vector for the converter based on the transition of a Petri net. The significant advantages of DPC based on Petri nets compared to traditional switching tables are that hysteresis comparators are not required, and the classical regulation of active and reactive powers is achieved in all sectors. Simulation and testing findings demonstrated excellent performance, supporting the viability of the suggested control approach using Petri nets.

Disturbance-Suppression Method of Direct-Driven PMSG-Based Wind Power System in Microgrids

In order to solve the current fluctuation problem in microgrids, a suppression method called the Direct-driven Permanent Magnet Synchronous Generator (DPMSG)-based Wind Power System (WPS) based on an adaptive enhanced moving average filter algorithm is proposed. Firstly, the mathematical model of the WPS is established. On this basis, the suppression method under unbalanced conditions is derived by the instantaneous power equation to ensure the stable operation of the microgrid. In order to improve the dynamic compensation capability of the DPMSG-based WPS, an enhanced moving average filtering algorithm with frequency adaptability is proposed. The positive and negative sequence components are obtained in the dq frame by this filtering algorithm. Subsequently, the angular frequency of the microgrid is obtained according to the changing phase, which realizes the high-performance control of the WPS and avoids the complicated parameter adjustment of traditional methods. The correctness of this method is verified by the simulation results. The DPMSG-based WPS with the proposed method can improve the stability of the microgrid.

Improving the quality of electricity in power supply systems with reservation from diesel generator plants

Subject of research: substantiation of the parameters and application of FACTS-devices of the STATCOM type for improving the quality of electricity in power supply systems with redundancy from diesel generator sets.
 Purpose of research: is to substantiate technical solutions based on semiconductor devices with reactive and active power generation aimed at improving the quality of electricity in remote power supply systems powered in backup mode from diesel generator sets.
 Methods and objects of research: fast Fourier transform, instantaneous power theory, simulation in Matlab Simulink. The object of research is the power supply system with a complete transformer substation 10/0.4 kV and redundancy from diesel generator sets.
 Main results of research: the article presents the features of ensuring the redundancy of the considered power supply system, taking into account the quality of electricity and the rationale for technical solutions to improve it when supplying the household loads of the village in the backup mode from the DGU based on simulation modeling. A spectral analysis of a sharply variable load curve was performed. It is proposed to use a three-level STATCOM at a voltage of 0.4 kV with a supercapacitor storage, which requires less storage energy than a buffer storage, to ensure the quality of electricity when powered by a diesel generator set. The results of the studies carried out testify to the prospects of using STATCOM with a storage device to improve the quality of electricity in low-voltage networks.

Reduced sensor based single stage charger with four quadrant capabilities using predictive control

Single stage battery chargers eliminate the DC link capacitor stage between two stage power conversion. In this work, a reduced sensor based four quadrant charger with single stage power conversion is realized with AC–DC matrix converter topology. Although, a small capacitor filter on DC side is used in this configuration, it is only required to supply or absorb high frequency ripple component of the battery current, to prevent the battery from being damaged. The grid current estimation is done using the converter switching model and AC side filter model, leading to the elimination of grid current sensor. The simple model predictive control used here in conjunction with instantaneous reactive power theory, avoids the use of any proportional integral controller, thus making the control scheme simpler. The single stage design increases power density, and the charger’s dependability is increased by the absence of a large electrolytic capacitor. While the battery charges and receives power from the grid, the AC–DC matrix converter used here, performs a voltage bucking function. The simulation results and experimental findings from a lab-developed hardware prototype are used to validate the design and control of the proposed charger.

Performance evaluation of transformerless photovoltaic inverter

ABSTRACT The instantaneous power of 1- ϕ solar photovoltaic system comprising of high-gain DC-DC converter and 1- ϕ photovoltaic inverter has a twice line frequency that creates the undesirable second order harmonic current. This paper provides topological changes in both DC-DC converter and DC-AC inverter to mitigate the undesirable second-order harmonic current. Re-boost converter is used instead of boost converter, and power decoupling-based 1- ϕ inverter is used for the inverter purpose. To provide adequate DC-link voltage, standard maximum power point tracking scheme is used. To control the output of inverter, fixed-frequency sliding mode controller is used that provides better response in steady state as well as transient state conditions.

High-performance triboelectric nanogenerators incorporating chlorinated zeolitic imidazolate frameworks with topologically tunable dielectric and surface adhesion properties

Triboelectric nanogenerator (TENG), a device that can convert mechanical energy into electricity based on the principle of triboelectrification, has gained tremendous attention since its first discovery in 2012. Although TENG has versatile applications in energy harvesting and self-powered sensing, its commercialization is still limited by the low power output. Recently, metal-organic frameworks (MOFs), with their large surface area and excellent tunability, have been explored to enhance the electrical performance of TENG. Herein, we synthesized nanoparticles of hydrophobic zeolitic imidazolate framework ZIF-71 (RHO topology) and its non-porous counterpart ZIF-72 (LCS topology), which were subsequently incorporated in a polydimethylsiloxane (PDMS) matrix as filler materials. By modifying the topology of ZIF nanofillers, we found the dielectric constant and surface adhesion of composites are both enhanced, thereby generating significantly higher triboelectric output. Moreover, we show the resultant ZIF/PDMS nanocomposite films exhibit enhanced triboelectric properties and long-term stability under cyclic mechanical loading. After integrating the prepared nanocomposite films into TENG devices, we accomplished the peak output voltage and current of 578 V and 19 μA for thin films (3 ×3 cm2, thickness ∼0.33 mm), respectively, by embedding 1 wt % of ZIF-72 nanoparticles into PDMS matrix, with an instantaneous maximum power density of ∼5 W m−2. In this study, the mechanism of improved TENG performance by incorporating MOF nanoparticles has, for the first time, been revealed through nanoscale-resolved mechanical and chemical studies. Furthermore, the practicality of MOF-based TENG was demonstrated by harvesting energy from oscillatory motions, for powering up commercial microelectronics, transmitting electrical signals remotely, and functioning as a self-powered Morse code generator.

Performance Analysis and Comparison of an Experimental Hybrid PV, PVT and Solar Thermal System Installed in a Preschool in Bucharest, Romania

The demand for on-site production of energy is showing a rapid increase as the trend of decentralisation and energy self-reliance gains momentum. This paper studies and compares three of the main solar energy technologies: photovoltaic, solar thermal panels and hybrid photovoltaic thermal panels. A prototype experimental installation consisting of the aforementioned technologies was set up on the campus of University Politehnica Bucharest. Data were collected over several months, then the instantaneous power production and overall system performance was computed. The system was analysed in four types of weather patterns, and its suitability was assessed in each case. The results show that the performance of PVT panels is closely connected to the dissipation of the thermal energy collected in the thermal storage tank. In addition, PVT collectors can outperform the PV panels in accordance to the thermal energy demand of the end user when used in an installation with suitable dimensions.

Paper-based ZnO self-powered sensors and nanogenerators by plasma technology

Nanogenerators and self-powered nanosensors have shown the potential to power low-consumption electronics and human-machine interfaces, but their practical implementation requires reliable, environmentally friendly and scalable processes for manufacturing and processing. Furthermore, the emerging flexible and wearable electronics technology demands direct fabrication onto innovative substrates such as paper and plastics typically incompatible with high process temperatures. This article presents a plasma synthesis approach for the fabrication of piezoelectric nanogenerators (PENGs) and self-powered sensors on paper substrates. Polycrystalline ZnO nanocolumnar thin films are deposited by plasma-enhanced chemical vapour deposition on common paper supports using a microwave electron cyclotron resonance reactor working at room temperature yielding high growth rates and low structural and interfacial stresses. Applying Kinetic Monte Carlo simulation, we elucidate the basic shadowing mechanism behind the characteristic microstructure and porosity of the ZnO thin films, relating them to an enhanced piezoelectric response to periodic and random inputs. The piezoelectric devices are assembled by embedding the ZnO films in polymethylmethacrylate (PMMA) and using Au thin layers as electrodes in two different configurations, namely laterally and vertically contacted devices. We present the response of the laterally connected devices as a force sensor for low-frequency events with different answers to the applied force depending on the impedance circuit, i.e. load values range, a behaviour that is theoretically analyzed. The characterization of the vertical devices in cantilever-like mode reaches instantaneous power densities of 80 nW/cm2 with a mean power output of 20 nW/cm2. Besides, we analyze their actual-scenario performance by activation with a fan and handwriting. Overall, this work demonstrates the advantages of implementing plasma deposition for piezoelectric films to develop robust, flexible, stretchable, and enhanced-performance nanogenerators and self-powered piezoelectric sensors compatible with inexpensive and recyclable supports.

A Self-Charging Concentration Cell: Theory

Batteries are a key resource in the quest for sustainable energy. Here, the theoretical basis is presented for a new type of electrochemical concentration cell that might contribute to this enterprise. The cell, which has been successfully demonstrated in the laboratory, incorporates a chemically asymmetric membrane to drive anisotropic diffusion between two solution chambers; the resulting concentration difference powers the cell. In this study, the membrane’s operation is validated via three theoretical approaches: (i) traditional equilibrium thermodynamics; (ii) balancing drift and diffusion current densities; and (iii) the time-independent diffusion equation. The physical criteria for its operation are developed and its dimensionless variables identified. The cell’s maximum instantaneous power density might exceed 107 W/m3. Its self-charging capability should confer multiple advantages over traditional concentration cells (as well as over some voltaics), including improved thermodynamic efficiency, economy, and compactness. Commonalities with other electrochemical systems (e.g., liquid chromatography, metal corrosion, and solid state diodes) are discussed, and a physical instantiation of the cell is reviewed. Recent numerical simulations corroborate its essential processes.

Backstepping Based Grey Wolf and DPC for Power Quality Improvement and Active Power Injection in PV Grid-connected System Based on Interleaved Boost Converter

This research offers the backstepping based grey wolf control design for a multifunctional PV grid-connected system (MPGC) based on four phases interleaved boost converter. This work proposes a solution to the issues of harmonic mitigation, reactive power compensation, and PV-generated power injection into the grid-based MPGC. The interleaved boost converter (IBC), controlled using maximum power point tracking (MPPT), is utilized to harvest the photovoltaic (PV) system's peak power and overcome the conventional topology's drawbacks. Direct power control (DPC) based on space-vector pulse width modulation (SVPWM) is used to control the instantaneous power of the MPGC, and the backstepping control (BSC) is applied to the whole system to maintain the robustness and stability of the suggested method. The Grey Wolf Optimizer (GWO) optimized the system's dynamic response by adjusting the BSC parameters. The results were obtained using MATLAB/Simulink software. The suggested work shows excellent performance based on the obtained results, achieving the sinusoidal waveform of the currents and a unity power factor. Total harmonic distortion (THD) has been decreased below 5% in accordance with IEEE 519-2014 standard.

NEW MODELING AND ENHANCED CONTROL STRATEGY FOR GRID-CONNECTED FOUR-LEG INVERTER WITHOUT PHASE-LOCKED LOOP AND PARK’S TRANSFORMATION

This paper proposes an enhanced voltage-oriented control strategy (EVOC) based on super twisting sliding mode control (STSMC) for a grid-connected four-leg source voltage inverter (GC-FLVSI) in the synchronous rotating frame (dq0–frame) without using a phase-locked loop (PLL) and Park's transformation. The proposed strategy is used not only to control the dq0–axes FLVSI inject currents but also to derive the mathematical model of the GC-FLVSI in the dq0–frame based on the direct instantaneous power control theory (DPC) and to eliminate the impact of PLL and Park's transformation. The principle of the proposed EVOC strategy is analyzed in detail. The STSMC is used for accurate dq0–axes FLVSI inject current control, and it can result in sinusoidal currents with high quality, high robustness against parametric variations, and low chattering with easy implementation. Finally, the superiority of the proposed EVOC-STSMC strategy in terms of complexity, response, steady-state errors, robustness, total harmonic distortion (THDs) mitigation, neutral current reduction, and robustness against parameter variations is verified through comparative analysis with the EVOC strategy based on the PI controller (EVOC-PIC).