Power Characteristics Research Articles

Ultra-short-term wind power forecasting based on a dual-channel deep learning model with improved coot optimization algorithm

The large-scale integration of wind power to the grid poses some potential challenges to the power system. Accurate wind power forecasts reduce the impact of the nonlinearities and volatility of wind power generation. A two-channel deep learning model based on an improved coot optimization algorithm (ICOA) is proposed. First, the use of long short-term memory (LSTM) builds a channel for the extraction of chronological characteristics of historical power. Second, a temporal convolutional network (TCN) is adopted as a hybrid feature-extraction channel for multi-dimensional meteorological data, and by incorporating the self-attention mechanism (SA), the ability of TCN to extract internal information from meteorological features is enhanced. Finally, the ICOA that introduces nonlinear decision factor, adaptive dynamic boundary, and Cauchy mutation is used to optimize the model hyperparameters. The simulation analysis is carried out on the winter and summer measured data of a wind farm in Xinjiang. The results show that compared with the traditional LSTM model, the root mean square error and the mean absolute error of the proposed method are reduced by 10.35 % and 16.27 % on average, respectively, and the prediction accuracy is higher than that of other comparative models, which verifies the superiority of our proposed model.

Lithium Battery SoC Estimation Based on Improved Iterated Extended Kalman Filter

With the application of lithium batteries more and more widely, in order to accurately estimate the state of charge (SoC) of the battery, this paper uses the iterated extended Kalman filter (IEKF) algorithm to estimate the SoC. The Levenberg–Marquardt (LM) method is used to optimize the error covariance matrix of IKEF. Based on the hybrid pulse power characteristics experiment, a second-order Thevenin model with variable parameters is established on the MATLAB platform. The experimental results show that the proposed model is effective under the constant current discharge condition, the Federal Urban Driving Schedule (FUDS) condition, and the Beijing dynamic stress test (BJDST) condition. The results show that the simulation error of the improved LM-IEKF algorithm is less than 2% under different working conditions, which is lower than that of the IKEF algorithm. The improved algorithm has a fast convergence speed to the true value, and it has a good estimation accuracy in the case of large changes in external input current. Additionally, the fluctuation of error is relatively stable, which proves the reliability of the algorithm.

Вимоги до вибору значень параметрів радарів із синтезованою апертурою на базі малих космічних апаратів дистанційного зондування Землі

Present-day small satellites for Earth remote sensing have found wide practical application in solving different problems in the socio-economic and defense areas. The use of small satellites is justified as a basis for the formation both of large constellations and constellations of several spacecraft or single spacecraft with the aim to reduce the cost of Earth remote sensing information. The miniaturization of electron components and the latest technological advances have made radar systems compatible with small satellites. The goal of this paper is to present, based on small satellites, expressions for calculating the key parameters of radar systems and their analysis and to calculate possible values of the parameters considered. Possibilities in principle of using synthetic aperture radars (SARs) are considered. The paper presents an overview of Internet sources that give broad information on the recent trends, technologies, and use SAR-equipped satellites. Particular attention is paid to the development of mini- and microspacecraft with X-band SARs operating, in particular, in the stripmap and spotlight modes. The key parameters that have an effect on the SAR possibility of producing high-quality images are presented. By the example of the ICEYE constellation of small satellites, important technical characteristics and parameters of modern radar systems equipped with an active phased array antenna are presented. A model of SAR imaging in the stripmap mode is considered. In the approximation of a rectangular antenna aperture, expressions are given to estimate the slant and the horizontal range resolution and the azimuthal resolution. The available range of the small-satellite SAR pulse repetition frequency is estimated. Relationships between the maximum swath width and the minimum SAR pulse repetition frequency are presented. Expressions are given to estimate the antenna dimensions, the SAR sensitivity, and the signal-to-noise ratio. The presented expressions allow one to analyze the effect of the main technical characteristics and parameters of minisatellite SARs on the design and power characteristics of small satellites and the orbit parameters. The obtained results make it possible to develop recommendations on the design of imaging equipment for home low-orbit satellites and their constellations.

Modeling end-to-end delays in TSCH wireless sensor networks using queuing theory and combinatorics

Wireless communication offers significant advantages in terms of flexibility, coverage and maintenance compared to wired solutions and is being actively deployed in the industry. IEEE 802.15.4 standardizes the Physical and the Medium Access Control (MAC) layer for Low Power and Lossy Networks (LLNs) and features Timeslotted Channel Hopping (TSCH) for reliable, low-latency communication with scheduling capabilities. Multiple scheduling schemes were proposed to address Quality of Service (QoS) in challenging scenarios. However, most of them are evaluated through simulations and experiments, which are often time-consuming and may be difficult to reproduce. Analytical modeling of TSCH performance is lacking, as only one-hop communication with simplified traffic patterns is considered in state-of-the-art. This work proposes a new framework based on queuing theory and combinatorics to evaluate end-to-end delays in multihop TSCH networks of arbitrary topology, traffic and link conditions. The framework is validated in simulations using OMNeT++ and shows below 6% root-mean-square error (RMSE), providing quick and reliable latency estimation tool to support decision-making and enable formalized comparison of existing scheduling solutions.

Security assessment and preventive control of combined electricity and heat systems with distributed electric thermal storage

Achieving carbon peak and neutrality targets can be accelerated by reducing wind power curtailment (WPC). However, WPC is constrained due to the electric thermal coupling characteristics of combined heat and power. To tackle this challenge, we propose an optimal scheduling framework for combined electricity and heat systems (CEHS) with distributed electric thermal storage (DETS) and perform security assessment and preventive control. Firstly, a general model is proposed to schedule DETS for different types of customers. The customer flexibility regulation variable (CFRV) for each customer is developed to fill this knowledge gap, and the excess thermal storage stored in DETS is used for auxiliary thermal network regulation (ATNR). Secondly, a two-stage security assessment and preventive control method for CEHS with DETS is proposed to correct overloaded branch flow. Thirdly, an evaluation index is developed to evaluate the severity of overloaded branches. The results show that the method of considering CFRV can reduce WPC and operation costs compared to the traditional method. Adopting ATNR enhances the flexibility and economics of grid scheduling compared to non-ATNR. Moreover, assessments of overloaded branches in various cases show that the preventive control method mitigates overload risks.

Determination of Anaerobic Power, Agility and Some Physical Characteristics of Turkish Elite Greco-Roman Style Young Wrestlers

Anaerobic power, agility and owned physical characteristics are the most important characteristics that determine sportive success and performance in wrestling. In this study, these characteristics of Turkish Elite Greco-Roman Style Young Wrestlers were determined. Because better preparation of the training programs to increase the performance of the athlete depends on determining the athlete profile in the best way in advance and creating it based on a scientific method. Determining the anaerobic power and agility characteristics of wrestlers will be one of the most important data in predicting their sports performance. 37 elite Greco-Roman style young wrestlers who have achieved success at national and international level participated in the research. The findings obtained because of this study will also contribute to the revision of the wrestlers' training programs. Average age of the athletes is 18.6±1 Years, their body weight is 76±16.1 Kg., their height is 175±1 cm., their body fat percentage is 10.8±4.6, and their body mass index is 24.8±3.8 kg/m2. In the made Wingate Test, the highest anaerobic power for the arm was 9.95±2.51 w/kg, and the average was 4.68±0.7 w/kg. The same measurements were determined as 14.68±2.52 w/kg at the highest and 7.17±0.8 w/kg on average for the leg. Illinois agility test result was found 15.9±0.8 sec. With these results, it has been observed that the measured performance values of Turkish elite Greco-Roman style young wrestlers are above the average and are consistent with the studies found in the literature.Keywords: Agility, Anaerobic Power, Greco-Roman Style Wrestling

Optimal allocation of offshore wind power and energy storage considering source-load power stochasticity

Abstract Large-scale offshore wind generation has been integrated to power grids in China. The annual increase in electric vehicles, air conditioning systems, and other electrical facilities has intensified the randomness and volatility of power supply and demand, presenting significant challenges to the safe and economical operation of power systems. Energy storage systems serve as regulators in the power grid, yet the electrical performance and costs associated with various storage technologies differ considerably. Consequently, the strategic planning and development of energy storage solutions tailored to specific local conditions have emerged as critical areas of research. This paper presents an in-depth analysis of power characteristics across source loads, explores an optimized configuration approach for energy storage, and validates this method through a numerical example. The findings confirm the effectiveness of the proposed configuration strategy and offer pertinent recommendations for the implementation of energy storage solutions.

Studying the Impact of Shading on the Energy Characteristics of a Solar String

The current article presents an analysis of the impact of shading on the characteristics of a solar string, with and without the presence of bypass diodes. A solar string consisting of four solar modules was used for this purpose. Experiments were sequentially conducted by connecting one, two, and four bypass diodes. The study was conducted in laboratory conditions using an artificial light source while maintaining the cell temperature mode. The obtained results were analyzed concerning the volt-ampere characteristics, power characteristics, and the coefficient of performance of the photovoltaic string. All the obtained characteristics are compared with the characteristics of the non-shaded solar string.

STUDY OF THE EFFICIENCY OF SEARCH ALGORITHM FOR SELECTING THE MAXIMUM POWER OF SOLAR PANELS USING A DC-DC BOOST CONVERTER

The results of the study of the effectiveness of the search algorithm for selecting the maximum power from solar panels by a step-up pulse semiconductor converter in the conditions of dynamic changes in illumination are presented. An analysis of the mathematical model of solar panels was carried out, which determines the volt-ampere characteristics and power characteristics of the solar panel as a function of its voltage. A search algorithm for determining the mode of operation of the semiconductor converter, which ensures the mode of maximum power selection from solar panels, has been developed. This algorithm can be applied to various types of converters, in which the value of the input current depends on the filling factor of pulse-width modulation. In the Matlab software, a corresponding simulation model of the DC-DC boost converter, which selects the power of solar panels at different levels of solar radiation, was developed, with the help of which the efficiency of the developed algorithm was determined. In the course of the simulation, it was determined that the developed algorithm provides a fairly high efficiency of solar panel power extraction, which is a fairly high indicator compared to the described algorithms. It was determined that the dynamic properties of the semiconductor converter, which takes power from solar panels, directly affects the time of transition to the mode of taking maximum power. During the first switch-on, the output to the point of maximum power is about 1.2 seconds, in further operation, the transition occurs almost instantaneously for a time that corresponds to the time constant of the converter. Given that the processes of changing the level of sunlight take minutes, this time is acceptable.

Comparative analysis of the effectiveness of passive and active filters of higher harmonics as part of the electrical complex of metal heat treatment

The presence of a nonlinear load connected to the power supply network causes a distortion of the sinusoidal shape of the current and voltage curves, resulting in higher harmonics. Higher harmonics lead to overloading and overheating of equipment, reduced reliability and reduced service life, and can have a negative impact on the quality of electricity. As part of the task of ensuring the reliability of power grids, an important task is to control the level of harmonic components and use special devices to minimize their impact. To combat higher harmonics in power grids, various devices have been developed and used, including line chokes, passive filters, and active filters. The choice of a particular device depends on the parameters of the power grid, the type and characteristics of the connected load, the level of harmonic components, and the requirements for the quality of electricity. Linear chokes are capable of reducing the level of harmonics in the power grid, but, having a number of disadvantages, require additional justification when deciding on their use. A passive filter has a circuit consisting of a choke, resistor, and capacitor, can have different configurations, and is tuned to the frequency of a specific harmonic to suppress its effects. Passive filters are more effective in combating higher harmonics generated by nonlinear noise, more economical and easier to maintain, but have a limited frequency range, fixed parameters and significant weight and dimensions, which limits their use. Active filters include active components to generate signals that are out of phase with harmonic components, thus compensating for higher harmonics. Active filters are more flexible, capable of correcting distorted and shaped signals, are much more efficient than chokes and passive filters, but are less cost-effective and more power-consuming. In the presented work, a passive six-link LC filter and a shunt active filter based on the principle of instantaneous compensation of active and reactive currents are investigated. In the active filter, harmonic distortion compensation is provided by a proportional-integral controller. In this paper, we have carried out simulation modeling of passive and active filters as part of an electrical complex for metal heat treatment and analyzed the results of harmonic distortion compensation

Влияние конструктивных характеристик манипулятора харвестера на оптимальные размеры рабочей зоны

The efficiency of using logging machines on a steep slope depends on many factors, including the working area of the manipulator, which can be implemented in various technological modes of operation. The geometric parameters of the implemented working area are determined by the working position of the machine in the appropriate technological mode, that is, the place of installation of the machine relative to the tree or group of trees to be harvested. Optimization of the manipulator’s working area, formed during the operation of a logging machine, is one of the most effective ways to increase its productivity. In this article, based on a previously developed mathematical model for optimizing the structural dimensions of the links of a four-link articulated hydraulic manipulator designed for spatial manipulation of the harvester head when cutting and stacking trees for further transportation to the loading area, an analysis of the influence of the main geometric and power characteristics of the harvester on the optimal size of the working area is performed.

Evaluation Method for Underwater Ultrasonic Energy Radiation Performance Based on the Spatial Distribution Characteristics of Acoustic Power.

In recent years, underwater wireless ultrasonic energy transmission technology (UWUET) has attracted much attention because it utilizes the propagation characteristics of ultrasound in water. Effectively evaluating the performance of underwater ultrasonic wireless energy transmission is a key issue in engineering design. The current approach to performance evaluation is usually based on the system energy transfer efficiency as the main criterion, but this criterion mainly considers the overall energy conversion efficiency between the transmitting end and the receiving end, without an in-depth analysis of the characteristics of the distribution of the underwater acoustic field and the energy loss that occurs during the propagation of acoustic waves. In addition, existing methods focusing on acoustic field analysis tend to concentrate on a single parameter, ignoring the dynamic distribution of acoustic energy in complex aquatic environments, as well as the effects of changes in the underwater environment on acoustic propagation, such as spatial variability in temperature and salinity. These limitations reduce the usefulness and accuracy of models in complex marine environments, which in turn reduces the efficiency of acoustic energy management and optimization. To solve these problems, this study proposes a method to evaluate the performance of underwater ultrasonic energy radiation based on the spatial distribution characteristics of acoustic power. By establishing an acoustic power distribution model in a complex impedance-density aqueous medium and combining numerical simulation and experimental validation, this paper explores the spatial variation of acoustic power and its impact on the energy transfer efficiency in depth. Using high-resolution spatial distribution data and actual environmental parameters, the method significantly improves the accuracy of the assessment and the adaptability of the model in complex underwater environments. The results show that, compared with the traditional method, this method performs better in terms of the accuracy of the acoustic energy radiation calculation results, and is able to reflect the energy distribution and spatial heterogeneity of the acoustic source more comprehensively, which provides an important theoretical basis and practical guidance for the optimal design and performance enhancement of the underwater ultrasonic wireless energy transmission system.

The relationship between ceramic additives among structural, morphological, shielding, and stopping power features of BN/ZnFe metal matrix materials

Ionizing radiation has many negative effects on human health. These include eye and skin disorders and DNA damage inside cells. To eliminate or reduce these destructive effects of radiation, economical, low-corrosion, effective shielding materials with high absorption properties are needed. In this study, zinc-iron-based metal matrix composite materials with various proportions of boron nitride were produced on steel substrates. The structural and surface properties of the materials were examined with XRD and SEM images, respectively. These structures were irradiated with radioactive Am-241, Sr-90, Na-22, and Co-60 sources for their radiation shielding properties. Then, the absorption ratios in the samples were investigated according to the reinforced ceramic amounts in their content. In addition to the experiment, the stopping power and range values of the samples were calculated to check the reliability of the results. ZnFe alloys and composites are based on the dominant peaks of the heta (ƞ) phase of zinc. The amount of boron nitride added to the electrolyte significantly affected the crystal structure, while the incorporation of boron nitride into the zinc-iron matrix impressed the average grain size of the coating. The microstrain and dislocation densities of the film first decreased to 15 g/L and then increased depending on the ion diameter. The BN doping made the porous surface smooth, crack-free, and compact. It was found that the absorption rates for radiation increased as the amount of boron nitride in the samples increased. According to the rising amount of boron nitride, the absorption percentages are between 1.88 and 6.19% for alpha particles, 0.78–3.06% for electrons, 0.77–6.56% for positrons, and 0.61–6.34% for gamma photons. When the stopping power and range values were averaged, the amount of boron nitride increased directly and inversely with the stopping power and range values, respectively.

Analysis of wake and power fluctuation of a tidal current turbine under variable wave periods

In the Marine environment, waves and turbulence usually coexist, affecting the operation performance of the tidal current energy turbine. This paper conducts experiments on a scaled tidal stream turbine to study the wave period effect on the wake and power characteristics. Under a wave-current environment, the wake is found to display Gaussian distribution. Within the 4 times diameter downstream range (4D), the turbulence is significant, and both the wake velocity loss and fluctuation increase first and then decrease with wave period. After 6D, the flow field gradually recovers to the inflow level. The wave period affects the transversal turbulence, more in the near than far wake region, as the significant turbulence intensities at the hub and blade tips gradually merge and become consistent after 6D. The wave period affects little the power coefficient CP owing to the sinusoidal inflow velocity nature. However, the amplitude of the phase average power increases first and then decreases with the wave period. By contrast, the phase average power fluctuations are sensitive to cycle changes only within the low TSR interval; they decrease sharply with TSR. In addition, the energy distribution of power fluctuation in the wave flow coupling environment is mainly concentrated at the sum and difference, and as well multiples, of the rotational and wave frequency. The wave and its multiples energy distribution increases and then decreases with the wave period.

Metagoverning collaborative networks: a cumulative power perspective

Collaborative networks are gaining momentum in research and practice as a tool to solve complex problems and create public value. While being characterised as self-regulating and relatively autonomous, collaborative networks have been widely recognised to need metagovernance to drive their collaborative process forward. However, limited attention has been paid to how metagovernors exercise power without undermining the capacity of collaborative networks to solve collective problems. To contribute to this knowledge gap, we develop a new theoretical framework based on a cumulative power perspective in the context of the metagovernance of collaborative networks. We outline three modalities of metagovernance (output, input and process) through which metagovernors can exercise power by structurally privileging either their own interests or those on whose behalf they metagovern. We apply the theoretical framework to a Danish case study of collaborative networks in sustainable housing. Through this case, we showcase the repressive and constructive features of power in the metagovernance of collaborative networks. A key research finding is that metagovernors can improve their awareness of how to balance constructively and repressively exercising and distributing power in collaborative networks by understanding the power dynamics entangled in the different modalities of metagovernance.

Identification of User Requirements and their Influencing Factors Based on Online Reviews and Operational Data

It is crucial for enterprises to clearly identify user needs during the process of formulating product design improvement plans. Therefore, it is essential to comprehensively and accurately identify user needs, explore the reasons behind the emergence of these needs, and incorporate user opinions into the process of product design improvement. A method is proposed to comprehensively and accurately capture user requirements and address the challenge of identifying the underlying causes of user requirements. This method utilizes online comments and operational data to identify user requirements and their influencing factors. First, text sentiment analysis techniques are employed to quantify the importance and performance values of product feature topics. Second, we construct a quadrant model to identify product features requiring improvement, and the original negative comments related to these features are traced. However, the quadrant model alone is insufficient to reflect specific product issues that users are concerned about. Therefore, a functional structure model based on product issues is designed to filter and identify factors that influence user requirements using operational data. Finally, a Bayesian network inference approach is utilized to identify the key influencing factors on user requirements, enabling analysis of the causes behind user requirements and the proposal of product design improvement strategies. The feasibility and effectiveness of the proposed method are validated through experiments conducted on heavy-duty truck data. By analyzing the original negative comments related to the power characteristics, specific user demands regarding the insufficient power of the product were identified, such as “obviously insufficient power when climbing slopes” and other issues. Based on the vehicle power system functional structure model, combined with expert knowledge and operational data, factors related to the state of parts and user behavior that may affect “insufficient vehicle power” were identified. Based on the analysis results, suggestions were made to improve the engine intake air temperature control strategy and to enhance vehicle performance by promoting correct user behavior through informational campaigns.

Non-intrusive load monitoring based on MoCo_v2, time series self-supervised learning

Traditional non-intrusive load monitoring (NILM) methods rely on massive historical labeled data. However, due to the privacy and high labeling cost of datasets, their generality and feasibility are limited, with poor performance in identifying devices with multiple states or similar features. To address this issue, this paper proposes an SSCL-LM framework based on temporal convolutional network (TCN), integrating contrastive self-supervised learning into NILM. Initially, through contrastive self-supervised pre-training, the framework learns well-represented load temporal characteristics from abundant unlabeled 1D power data. Then a small amount of labeled data is used to fine-tune the classifier to learn load categories represented by different temporal characteristics. Finally, test data is inputted into the model for load identification. Validating on the REDD dataset, the results demonstrate that with only 30% labeled data for fine-tuning, the proposed method achieves a 4.04% higher F1 score compared to traditional supervised methods. Moreover, utilizing only 1D power features, this method exhibits superior identification performance for devices with multiple states or similar features. Furthermore, this method enables performance transfer among loads of the same device with different parameters across different households, verifying its strong generalization and practicality.

Assessing the determinants of participation in the circular plastic economy by Nigerian students

Purpose This study aims to address the critical subject of building capacity for the circular economy in the global south. It complements the literature by providing information on the role of higher education institutions in developing skills for the circular plastic economy. Design/methodology/approach This study used a mixed method approach drawing on reflective analysis on qualitative data from 5 focus groups and 12 semi-structured interviews, and structural equation modelling of quantitative data from 151 students across 4 Nigerian Universities. Findings The results indicate that Nigerian university students are more likely to participate in the circular plastic economy through a high prominence of soft power features such as increased awareness, inspiration, idea generation, encouragement and capacity building. Research limitations/implications The main limitation of this study is with the sample. A larger data set, including other tertiary institutions such as private universities, polytechnics and schools of vocational studies, would strengthen the results. Practical implications The study underlines the importance of targeted policy interventions and pedagogic innovations to drive awareness and knowledge building among Nigeria’s youth population. Originality/value This study makes a novel contribution by using empirical evidence to determine the predictors of student participation in the circular plastic economy. This understanding is important for the development and implementation of appropriate policies that promote participation in the circular plastic economy. Furthermore, given the typical youthful age bracket of university students, any plans to achieve a systemic shift in the plastic value chain must involve the young generation.

Effect of Plasma Gas Type on the Operation Characteristics of a Three-Phase Plasma Reactor with Gliding Arc Discharge

Three-phase gliding arc discharge reactors are devices in which it is difficult to maintain stable plasma parameters, be it electrically, physically, or chemically. The main cause of plasma instability is the source, which is freely burning arcs in a three-phase system. In addition, these arcs burn at low currents and are intensively cooled, further increasing their instability. These instabilities translate into the electrical characteristics of the plasma reactor. The analysis for the four gases nitrogen, argon, helium, and air shows that the type of plasma-generating gas and its physical parameters have a strong influence on the operational characteristics of the plasma reactor. Current–voltage, power and frequency characteristics of the plasma reactor were plotted experimentally. Characteristics obtained in this way make it possible to determine the areas of effective operation of the plasma reactor, and to estimate the quality of the generated plasma. Based on the characteristics obtained, a method of controlling the plasma parameters can be developed.

THE INFLUENCE OF THE BRAND OF THE MATERIAL FROM WHICH THE MAGNETIC CORES ARE MADE ON THE POWER CHARACTERISTICS OF THE MAGNETIC SYSTEM

The influence of the grade of the material from which the magnetic conductors are made on the power characteristics of the magnetic system and magnetic coupling with highly coercive permanent magnets Nd–Fe–B with a residual magnetic induction of 1.22 T is considered. The material of the magnetic conductors is steel 15, steel 09Г2C and corrosion-resistant steel 08Х22H6T. On average, in the range of air gaps between sections of the magnetic system from 4 to 10 mm, the decrease in the specific shear force with magnetic conductors made of corrosion-resistant steel 08Х22Н6T, relative to magnetic conductors made of steel 15 is 17.88 %. The increase in the specific shear force with magnetic conductors made of steel 09Г2C relative to magnetic conductors made of steel 15 depends on the value of the air gap between the sections of the magnetic system and varies from 2.53 to 11.81 %.