In order to achieve the goals of carbon neutrality, large-scale storage of renewable energy sources has been integrated into the power grid. Under these circumstances, the power grid faces the challenge of peak shaving. Therefore, this paper proposes a coordinated variable-power control strategy for multiple battery energy storage stations (BESSs), improving the performance of peak shaving. Firstly, the strategy involves constructing an optimization model incorporating load forecasting, capacity constraints, and security indices to design a coordination mechanism tracking the target load band with the equivalent power. Secondly, it establishes a quantitative evaluation system using metrics such as peak–valley difference and load standard deviation. Comparison based on typical daily cases shows that, compared with the constant power strategy, the coordinated variable-power control strategy has a more obvious and comprehensive improvement in overall peak-shaving effects. Furthermore, it employs a “dynamic dispatch of multiple BESS” mode, effectively mitigating the risks and flexibility issues associated with single BESSs. This strategy provides a reliable new approach for large-scale energy storage to participate in high-precision peaking.
The forward kinematics of the Stewart platform is crucial for precise control and reliable operation in six-degree-of-freedom motion. However, there are some shortcomings in practical applications, such as calculation precision, computational efficiency, the capacity to resolve singular Jacobian matrix and real-time predictive performance. To overcome those deficiencies, this work proposes a hybrid strategy for forward kinematics in the Stewart platform based on dual quaternion neural network and ARMA time series prediction. This method initially employs a dual-quaternion-based back-propagation neural network (DQ-BPNN). The DQ-BPNN is partitioned into real and dual parts, composed of parameters such as driving-rod lengths, maximum and minimum lengths, to extract more features. In DQ-BPNN, a residual network (ResNet) is employed, endowing DQ-BPNN with the capacity to capture deeper-level system characteristics and enabling DQ-BPNN to achieve a better fitting effect. Furthermore, the combined modified multi-step-size factor Newton downhill method and the Newton–Raphson method (C-MSFND-NR) are employed. This combination not only enhances computational efficiency and ensures global convergence, but also endows the method with the capability to resolve a singular matrix. Finally, a traversal method is adopted to determine the order of the autoregressive moving average (ARMA) model according to the Bayesian information criterion (BIC). This approach efficiently balances computational efficiency and fitting accuracy during real-time motion. The simulations and experiments demonstrate that, compared with BPNN, the <i>R</i><sup>2</sup> value in DQ-BPNN increases by 0.1%. Meanwhile, the MAE, MAPE, RMSE, and MSE values in DQ-BPNN decrease by 8.89%, 21.85%, 6.90%, and 3.3%, respectively. Compared with five Newtonian methods, the average computing time of C-MSFND-NR decreases by 59.82%, 83.81%, 15.09%, 79.82%, and 78.77%. Compared with the linear method, the prediction accuracy of the ARMA method increases by 14.63%, 14.63%, 14.63%, 14.46%, 16.67%, and 13.41%, respectively.
Materials of engineering and construction. Mechanics of materials, Production of electric energy or power. Powerplants. Central stations
With the increasing adoption of lithium-ion batteries (LIBs) as the batteries of choice in electromobility, personal electronic devices, and so on, comes the challenge of ageing, which prevents the batteries from performing optimally and meeting the design intent. This is observed in the form of declining power capability due to the increase in resistance and the reduction in capacity that can be stored or discharged from them. Unfortunately, the cost of assessing batteries after the first use remains a daunting challenge. In our work, we propose an approach that carries out fast preliminary grading based on resistance and capacity by first connecting old cells of the same chemistry and model in series with resistors to limit the branch current, then connecting the branches in parallel to equalise the voltages. A Simulink model of NCR18650PF Panasonic cells with adaptive-series resistance is compared with a fixed-series resistance and found to improve the balancing time from over 24 h to just 8 h. Electrochemical impedance spectroscopy (EIS) was carried out on the individual balanced cells between 0.1 Hz and 5 kHz so that the real impedance, imaginary impedance, absolute impedance, and phase were compared with the SOH of the cells at each frequency. Results show that the imaginary impedance in the 6.6 Hz frequency range shows a good correlation coefficient > 0.98 with the SOH, especially with a state of charge (SOC) of about 75–85% for the LCO cells. By selecting only a sample from all the cells that covers a wide range of ages and carrying out a full-capacity checkup on them, a simple correlation with the SOH and the EIS measurements for different frequencies can be used to estimate the SOH of the other cells that were connected in the same parallel connection. This is a considerable time saving in the charge and discharge time on the other cells in facilities that lack the capacity for simultaneous cycling of all cells. There are also huge energy savings in not having to cycle all the cells. Therefore, it offers a more efficient approach to grading spent cells than carrying out full capacity tests.
Production of electric energy or power. Powerplants. Central stations, Industrial electrochemistry
Abstract Exploration of efficient and stable photocatalysts to mimic natural leaves for the conversion of atmospheric CO2 into hydrocarbons utilizing solar light is very important but remains a major challenge. Herein, we report the design of four novel metal–salen‐incorporated conjugated microporous polymers as robust artificial leaves for photoreduction of atmospheric CO2 with gaseous water. Owing to the rich nitrogen and oxygen moieties in the polymeric frameworks, they show a maximum CO2 adsorption capacity of 46.1 cm3 g−1 and adsorption selectivity for CO2/N2 of up to 82 at 273 K. Under air atmosphere and simulated solar light (100 mW cm−2), TEPT‐Zn shows an excellent CO yield of 304.96 μmol h−1 g−1 with a selectivity of approximately 100%, which represents one of the best results in terms of organic photocatalysts for gas‐phase CO2 photoreduction so far. Furthermore, only small degradation in the CO yield is observed even after 120‐h continuous illumination. More importantly, a good CO yield of 152.52 μmol g−1 was achieved by directly exposing the photocatalytic reaction of TEPT‐Zn in an outdoor environment for 3 h (25–28°C, 52.3 ± 7.9 mW cm−2). This work provides an avenue for the continued development of advanced polymers toward gas‐phase photoconversion of CO2 from air.
Production of electric energy or power. Powerplants. Central stations
Deploying an integrated energy system represents a critical pathway to alleviate energy supply pressure and improve energy efficiency. However, in existing works on the integrated energy system, the uncertainties and multi-type reserves over different scheduling stages have not been fully considered to warrant the stable operation performance of integrated energy systems under multiple scenarios. Based on these considerations, a distributed robust optimal scheduling of an integrated energy system considering adaptive Copula function and dynamic reserve is proposed. First, an adaptive Copula function is developed to accurately describe the dynamic correlation of wind/solar power output and the characteristics of joint output. At the same time, the quasi-Monte Carlo method is used to form a typical scenario set aiming at the uncertainty of power generation for renewable energy sources. Furthermore, the reserve provision model is proposed, and the ineffective upward reserve, ineffective downward reserve, loss load, and power curtailment are respectively developed to address the effect caused by the uncertainty of renewable energy sources. Then, based on scenario information of renewable energy sources, the operating cost in the day-ahead stage and the adjustment cost of the system under the worst scenario in the real-time stage are taken as the optimization objectives, and a two-stage distribution robust optimization scheduling model is constructed. The two-stage model is solved using a column-and-constraint generation algorithm. Finally, case studies are carried out to verify by Gurobi that the operation cost of distributionally robust optimization is 2.0704×104$, the lowest ineffective reserve cost of 208$ is the lowest, the proposed method has a good economy and robustness and is suitable for dealing with the uncertainty of renewable energy sources.
Production of electric energy or power. Powerplants. Central stations
RELEVANCE of research is the most preferred method of efficient rotor synchronous motor with some magnets. Currently, synchronous electric motors with ethereal magnets are increasingly used in various fields. For each task, it is necessary to implement s synchronous electric motor with small magnets with desire (torque, emotional cooling and many others). In order to make the most efficient use of a synchronized motor with universal magnets, methods are applied. TARGET. The usual methods of standard design of a synchronous motor with original magnets are aimed at determining the optimal parapets to be applied by changing them at a given value using indicative algorithms. The application of this approach is limited by parameterization, which is determined by the experience of the designer and manufacturing constraints. At present, the development of technologies for the production of metals and magnets, it has become possible to manufacture metals and detect magnets of various geometric shapes. It is this use of the topological estimation method. At present, topological modernization of large-scale construction, the application of topological strategy in the design of synchronous electric motors with federal magnets is only now gaining rapid development.METHODS. When solving the tasks set, a comparative analysis of various merged for comparative analysis of various methods for comparing the rotors of synchronous electrical motors with natural magnets was carried out.RESULTS. The article describes the relevance of the topic under consideration. The most effective methods for optimizing the rotors of synchronous electrical motors with permanent magnets are determines. The conditions under which the application of one or another method oh optimizing the rotor is most effective are determined.CONCLUSION. The article describes various method for optimizing the rotors of permanent magnet synchronous motors. The pros and cons of various optimization methods are described after studying various types of optimizations, it was concluded that the most effective optimization method is the topology optimization method for rotors of permanent magnets synchronous motors.
Production of electric energy or power. Powerplants. Central stations
DC microgrids, considered building blocks of smart grid technologies, are subjected to small-signal instability due to the extensive introduction of power electronics devices. Therefore, in this paper, a sequence Virtual Filter (VF) controller, which considers not only the longitudinal virtual parameters but also the lateral capacitance and resistance, is first developed to increase the flexibility of system stability adjustment compared to the Virtual Impedance (VI) controller. Then, as distribution feeders are normally unbalanced and the application of the proposed sequence VF controller may amplify the distortion of imbalances on DC voltage, a novel Reference Current Generation (RCG) strategy considering the VF controller is proposed for Grid-Connected Converter (GCC) to improve DC microgrid power quality. The double-frequency fluctuation of the DC-link voltage is eliminated by regulating the oscillation of the active power flowing into the converter instead of the Point of Common Coupling (PCC) to 0. The PSCAD simulation results illustrate that the sequence VF controller can enhance the stability adjustment since, in some cases, the system can only be stabilized by adjusting lateral parameters. On the other hand, the proposed RCG strategy can significantly reduce DC voltage fluctuations compared to the traditional approach. Furthermore, incorporating the proposed strategy with the sequence VF controller offers greater flexibility in reducing the negative-sequence current while maintaining a power transfer capacity for GCCs in a master–slave-based DC microgrid, comparable to that of the traditional strategy.
Production of electric energy or power. Powerplants. Central stations
Hua Zhang, Abuduwayiti Aierke, Yingtang Zhou
et al.
Abstract The construction of high‐efficiency and low‐cost non‐noble metal bifunctional electrocatalysts for water electrolysis is crucial for commercial large‐scale application of hydrogen energy. Here, we report a novel strategy with erbium‐doped NiCoP nanowire arrays in situ grown on conductive nickel foam (Er‐NiCoP/NF). Significantly, the developed electrode shows exceptional bifunctional catalytic activity, which only requires overpotentials of 46 and 225 mV to afford a current density of 10 mA cm−2 for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. Density functional theory calculations reveal that the appropriate Er incorporation into the NiCoP lattice can significantly modulate the electronic structure with the d‐band centers of Ni and Co atoms by shifting to lower energies with respect to the Fermi level, and optimize the Gibbs free energies of HER/OER intermediates, thereby accelerating water‐splitting kinetics. When assembled as a solar‐driven overall water‐splitting electrolyzer, the as‐prepared electrode shows a high and stable solar‐to‐hydrogen efficiency of 19.6%, indicating its potential for practical storage of intermittent energy.
Production of electric energy or power. Powerplants. Central stations
Poor cycling performance caused by massive volume expansion of silicon (Si) has always hindered the widespread application of silicon-based anode materials. Herein, bi-continuous silicon/carbon (Si/C) anode materials are prepared via magnesiothermic reduction of silica aerogels followed by pitch impregnation and carbonization. To fabricate the expected bi-continuous structure, mesoporous silica aerogel is selected as the raw material for magnesiothermic reduction. It is successfully reduced to mesoporous Si under the protection of NaCl. The as-obtained mesoporous Si is then injected with molten pitch via vacuuming, and the pitch is subsequently converted into carbon at a high temperature. The innovative point of this strategy is the construction of a bi-continuous structure, which features both Si and carbon with a cross-linked structure, which provides an area to accommodate the colossal volume change of Si. The pitch-derived carbon facilitates fast lithium ion transfer, thereby increasing the conductivity of the Si/C anode. It can also diminish direct contact between Si and the electrolyte, minimizing side reactions between them. The obtained bi-continuous Si/C anodes exhibit excellent electrochemical performance with a high initial discharge capacity of 1481.7 mAh g<sup>−1</sup> at a current density of 300 mA g<sup>−1</sup> and retaining as 813.5 mAh g<sup>−1</sup> after 200 cycles and an improved initial Coulombic efficiency of 82%. The as-prepared bi-continuous Si/C anode may have great potential applications in high-performance lithium-ion batteries.
Production of electric energy or power. Powerplants. Central stations, Industrial electrochemistry
To address system parameter changes during permanent magnet synchronous motor (PMSM) operation, an H∞ filtering algorithm with a dynamic forgetting factor is proposed for online identification of motor resistance and inductance. First, a standard linear discrete PMSM parameter identification model is established; then, the discrete H∞ filtering algorithm is derived using game theory reducing state and measurement noise influence. A cost function is defined, solving extremes values of different terms. A dynamic forgetting factor is introduced to the weighted combination of initial and current measurement noise covariance matrices, eliminating identification issues from different initial values. On this basis, a dynamic forgetting factor is added to weigh the combination of the initial measurement noise covariance matrix and the current measurement noise covariance matrix, which eliminates the influence of the discrimination error caused by the different initial values. Finally, the identification model is built in MATLAB/Simulink for simulation analysis to verify the feasibility of the proposed algorithm. The simulation results show the proposed H∞ filtering algorithm rapidly and accurately identifies resistance and inductance values with significantly improved robustness. The forgetting factor enables quick stable recognition even with poor initial values, enhancing PMSM control performance.
Materials of engineering and construction. Mechanics of materials, Production of electric energy or power. Powerplants. Central stations
Wenjiao Zhao, Julian Gebauer, Thomas Bergfeldt
et al.
Li<sub>1.11</sub>(Ni<sub>0.4</sub>Mn<sub>0.4</sub>Co<sub>0.2</sub>)O<sub>2</sub> powders were chemically delithiated by (NH<sub>4</sub>)<sub>2</sub>S<sub>2</sub>O<sub>8</sub> oxidizer to obtain Li<sub>x</sub>(Ni<sub>0.4</sub>Mn<sub>0.4</sub>Co<sub>0.2</sub>)O<sub>2</sub> powders. The thermal behavior of two delithiated specimens, Li<sub>0.76</sub>Ni<sub>0.41</sub>Mn<sub>0.42</sub>Co<sub>0.17</sub>O<sub>2.10</sub> and Li<sub>0.48</sub>Ni<sub>0.38</sub>Mn<sub>0.46</sub>Co<sub>0.16</sub>O<sub>2.07</sub>, was studied compared to the pristine specimen. Phase transitions at elevated temperatures were investigated by simultaneous thermal analysis (STA) and the gas evolution accompanying the phase transitions was analyzed by mass spectroscopy and an oxygen detector. The enthalpy of two delithiated samples and a pristine specimen were measured by a high temperature drop solution calorimeter. Based on these results, the enthalpies of formation were calculated.
Production of electric energy or power. Powerplants. Central stations, Industrial electrochemistry
The allowable harmonic current limits injected to the common connection points are stipulated for users respectively by GB/T 14549—93 and IEEE std.519:2014. However, there are some differences between two standards in determination methods and engineering application. The harmonics national standard GB/T 14549 under revision intends to adopt the emission limits of harmonic current for single user in IEEE std.519:2014. Therefore, it is necessary to fully discuss the rationality of the methods for determining the harmonic current limits. In this paper, the limits of the harmonic current in two standards are introduced, and their determination methods are deduced and discussed respectively. Finally, the similarities and differences between them are analyzed through case study.
Electricity, Production of electric energy or power. Powerplants. Central stations
Abstract Due to the growing demand for clean and renewable hydrogen fuel, there has been a surge of interest in electrocatalytic water‐splitting devices driven by renewable energy sources. However, the feasibility of self‐driven water splitting is limited by inefficient connections between functional modules, lack of highly active and stable electrocatalysts, and intermittent and unpredictable renewable energy supply. Herein, we construct a dual‐modulated three‐dimensional (3D) NiCo2O4@NiCo2S4 (denoted as NCONCS) heterostructure deposited on nickel foam as a multifunctional electrode for electrocatalytic water splitting driven by photovoltaic‐powered supercapacitors. Due to a stable 3D architecture configuration, abundant active sites, efficient charge transfer, and tuned interface properties, the NCONCS delivers a high specific capacity and rate performance for supercapacitors. A two‐electrode electrolyzer assembled with the NCONCS as both the anode and the cathode only requires a low cell voltage of 1.47 V to achieve a current density of 10 mA cm−2 in alkaline electrolyte, which outperforms the state‐of‐the‐art bifunctional electrocatalysts. Theoretical calculations suggest that the generated heterointerfaces in NCONCS improve the surface binding capability of reaction intermediates while regulating the local electronic structures, which thus accelerates the reaction kinetics of water electrolysis. As a proof of concept, an integrated configuration comprising a two‐electrode electrolyzer driven by two series‐connected supercapacitors charged by a solar cell delivers a high product yield with superior durability.
Production of electric energy or power. Powerplants. Central stations
Denison Gimenes Mesquita, Edson Da Costa Bortoni, Davi Marcelo Febba
et al.
This paper aims to present a technique to estimate the losses of a dry-type air-core reactor (DTACR) assembled with one cylinder based on calorimetry principles while employing infrared thermography techniques. The technique is intuitive, practical, and easy to apply both in a laboratory and in the field. Nowadays, the losses on DTACR can be measured only inside of specific laboratories and the equipment shall be disconnected from system and powered-off. Instead of installing contact temperature sensors in the reactor’s internal and external surfaces, temperature measurements were remotely performed with equipment in regular operation and the losses can be obtained by the method proposed. The paper presents the nature of the losses and the theoretical basis of the proposed method. The results obtained from the proposed technique are compared to those achieved by the standard method and used to calculate results through tests performed on prototypes.
Distribution or transmission of electric power, Production of electric energy or power. Powerplants. Central stations