bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of wavelet characteristics on single-phase grounding fault line selection
Authors: Gong Jing 
Published: February 2022

Abstract
It is difficult to select the fault line in distribution network because of the small single-phase grounding fault current. Wavelet transform is especially suitable for fault transient analysis because of its unique time-frequency localization performance. However, the characteristics of different wavelets have a direct impact on the line selection results. Improper selection of wavelets will directly lead to misjudgment. Firstly, the transient characteristics of single-phase grounding fault and the relationship between wavelet transform modulus maxima and singularity are analysed, and the line selection criterion of wavelet modulus maxima is given. Then, the influence of wavelet vanishing moment order, support length, symmetry, and orthogonality on the detection effect of signal singularity is analysed, and four principles for selecting wavelet in fault line selection are proposed. The larger the order of vanishing moment and support length, the more conducive to detection. The influence of vanishing moment order is much greater than that of support length. The 10kV system simulation model is built, five representative wavelets are selected to decompose the zero- sequence current of the fault line in four scales respectively, and the different modulus maxima corresponding to the sudden change point are compared. The experimental results prove the reliability of the wavelet selection principles proposed in this paper.
Effect of acid corrosion on properties of composite insulator core rod
Authors: Shen Hao , Liu Hui , Zhou Chao , Jia Ran , Zhang Yang , Liu Rong , Liu Chuanbin 
Published: February 2022

Abstract
In recent years, there have been a number of composite insulator decay-like fracture faults characterized by resin degradation and irregular fracture morphology, which seriously threaten the safety and stability of power system. At present, the research of composite insulator’s decay-like fracture is still in the initial stage at home and abroad, and there is no clear conclusion on the causes of its fracture, influencing factors and other important scientific and technical issues, and there is no unified understanding of the mechanism of decay-like fracture. In view of the above problems, this paper carries out acid corrosion test on core rod samples to explore the corrosion law of nitric acid on core rod and its influence on properties. The results show that acid corrosion is one of the factors causing the degradation of epoxy resin. With the increase of nitric acid concentration and soaking time, the degradation rate of epoxy resin accelerates, and the core rod sample gradually changes from emerald green to yellowish brown, then to light yellow, and finally to white hair like glass fibre. The effect of the sample under the long-time action of low concentration nitric acid is the same as that under the short-time action of high concentration nitric acid. Nitric acid will continuously erode into the core rod, resulting in the decrease of hardness and performance on the core rod surface.
Research on multi-objective optimal scheduling of virtual power plant based on self-supplied coal-fired power plants
Authors: Liu Wei , Cai Yanchun , Yang Chunxu , Qian Baiyun 
Published: February 2022

Abstract
With the development of renewable energy, improving the absorption capacity of power grid has become a difficult problem. It is very important to establish virtual power plants based on self-supplied coal-fired power plant to coordinate renewable energy consumption, especially in Xinjiang Province, China. This paper studied the optimal scheduling of a virtual power plant including wind turbines, photovoltaic units, and energy storage equipment based on the self-supplied power plant. First, a mathematical model of the power and power generation cost of each unit inside the virtual power plant was established, and the demand response mechanism was introduced. Secondly, a multi-objective optimization model is established by considering the maximization of net income of virtual power plants, the minimization of system coal consumption and the maximization of user interruption load benefits, and the use of analytic hierarchy process to determine the weights of three objective functions, of which user interruption load benefits are used to reflect the enthusiasm of users to interrupt the load. Finally, the particle swarm algorithm is used to solve the model. The optimization results show that when the coal price rises, the net income of the system decreases, and even a loss occurs, however, the change in coal price has little effect on the Interrupted load of user. In addition, multi-objective optimization can improve the enthusiasm of users while ensuring the net income of the system, it proves that the model has a good optimization effect.
Electricity-heat integrated agent modelling for participation in spot electricity market
Authors: Yin Xunhu , Wu Huahua , Su Huangxing , Meng Zhiquan , Yang Xingchao 
Published: February 2022

Abstract
Due to the limitation of market rules, many small capacity power plants cannot directly participate in the spot electricity market, reducing the ability of the market to optimize the allocation of power generation resources. Among these power plants, the electric power output of some combined heat and power (CHP) plants is constrained by their heat output, which should be considered in the dispatch. Therefore, the electricity-heat integrated agents are defined and introduced to aggregate small capacity power plants and participate in the spot electricity market. Firstly, the model of electricity-heat integrated agents is formulated based on the aggregation of the internal generators and CHP units. Then, the framework of the spot electricity market with the participation of electricity-heat integrated agents is constructed. Moreover, the market clearing model is further developed by combining the electricity-heat integrated agent model and the security constrained unit commitment model. Simulation results in the case verify the effectiveness of the proposed model and technique.
Application of least squares fitting algorithm in transformer terminal unit electrical quantities acquisition
Authors: Jiang Chao , Wang Fuliang , Ning Yan 
Published: February 2022

Abstract
In order to accurately estimate the frequency and harmonics of voltage and current signals acquired in transformer terminal unit (TTU), the least squares fitting algorithm is applied to its harmonic analysis. The principle of the algorithm and its flowchart are presented, and the implementation of the algorithm in TTU is primarily discussed. The noisy voltage signals with harmonics and signal frequencies ranging from 49.8 Hz to 50.2 Hz are generated and the real ones are acquired. The harmonic analysis results of the least squares fitting algorithm and the Hanning window and interpolation algorithm reveal that the errors in the signal frequency, direct current (DC) component, amplitude and phase of fundamental and harmonics of the former are only about 1/3 of that of the latter.
Study on aging index of mechanical and electrical properties of high temperature vulcanized silicone rubber
Authors: Zhou Chao , Jia Ran , Qin Jiafeng , Liu Hui , Li Na , Shen Hao 
Published: February 2022

Abstract
Composite insulators are affected by various factors in operation. With the increase of operation time, the shed of silicone rubber composite insulators will become hard and brittle. In this paper, it is found that the hardness of long-term silicone rubber shed meets the standard requirements. The tear strength, tensile strength, elongation at break, resistance to electric tracking and corrosion loss decrease significantly after 5-10 years of operation. The decline of silicone content on the micro surface and the escape of inorganic fillers are the reasons for the deterioration of macro performance. Finally, the evaluation system for aging performance of insulators is preliminarily established, according to the aging degree of insulator, operation and maintenance suggestions are proposed.
Optimal operation of district heat-electric system considering multi-energy flexibility
Authors: Xu Feng , Tao Yuanchao , Qiu Peng , Ding Chao , Lu Yi , Zhao Lebing , Qin Hongpei 
Published: February 2022

Abstract
With increasingly integration of the renewable energy, various uncertainties bring a severe challenge to the operation of the district heat-electric system (DHES). In order to enlarge the accommodation of renewable energy, this paper proposes an optimal operation method of integrated electricity and heat system considering the temporal-coupling feature of multi-energy flexibility. Firstly, the models of multi-energy devices are established to describe the energy conversion. The time delay of heat network is considered and the model of DHES is built as well. Then, considering the uncertainty of load, the time-related upward and downward flexibility constraints are established. The objective function of the optimal economic operation problem is formulated as three parts, including the purchasing price, the operation price, and the curtailment penalty of PV. Finally, a case study based on the IEEE 33-bus power distribution grid and 6-node district heating network is conducted to validate the effectiveness of the method.
Optimal dispatch of a thermal-electric virtual power plant considering heat storage tanks
Authors: Pan Weiwei , Yang Kan , Zhang Yunlei , Wang Dixin , Xu Kangxuan , Li Siying , Sun Shijie 
Published: February 2022

Abstract
Characteristic of thermoelectric coupling of Combined heat and power (CHP) units reduces the flexibility of power generation and heat generation in the “Three-North” region of China. Meanwhile, the uncertainty of renewable energy generation (REG) and demand side management (DSM) pose challenges to the optimal operation of the whole system, leading to difficulty in improving the economic benefits of the whole system. In order to mitigate the above problems, wind generators, solar generators, CHP units, conventional generating units, interruptible loads, battery energy storage systems (BESSs), as well as electric vehicles (EVs) are aggregated into a virtual power plant (VPP) as a community of interest. Particularly, heat storage tanks (HSTs) are introduced into VPP in this paper to realize the decoupling of heat and power of CHP units and enhance the flexibility of the VPP. Firstly, the composition and structure of the VPP are described. Secondly, a day-ahead optimal dispatching model of the VPP considering heat output is established. Finally, the effectiveness of the proposed model is verified by the modified IEEE30 bus system.
Research on heat and power load optimal dispatch based on improved grey wolf optimization algorithm
Authors: Hu Hao , Yang Li , Yu Xiaobing , Xue Yanping , Zhang Zengping , Zhou Gang 
Published: February 2022

Abstract
The heat and power load optimal dispatch (LOD) is a useful method for combined heat and power (CHP) plants to improve energy efficiency and reduce energy consumption. To obtain a better load dispatch effect, this paper proposes the improved grey wolf optimization (IGWO) algorithm and LOD problem constraint processing methods, which constitute three kinds of optimization schemes. The load optimal dispatch research is performed for a typical CHP plant consisting of seven units and different optimization schemes are discussed. The results show that the power generation cost obtained from the proposed optimization scheme is lower than the data obtained by a single algorithm in the literature. The results also indicate that the adopted constraint processing method can well solve the characteristics of multiple constraints of the LOD problem. Meanwhile, the comparison results of different schemes show that the IGWO algorithm has more obvious advantages in the performance of better convergence and robustness, meaning it is more suitable for solving the LOD problems. In short, the improved algorithm can accurately solve the load matching problem between power plants and power and heat grids, providing better solutions.
Low-frequency oscillation suppression strategy considering dynamic power characteristics of energy storage system
Authors: Wang Yunling , Liu Fang , Du Xinwei , Li Bo , Liu Yang , Jiang Libo 
Published: February 2022

Abstract
Aiming at the problem of low-frequency oscillation in the weak power grid, a low-frequency oscillation suppression strategy considering the dynamic power characteristics of the energy storage system (ESS) is proposed in this paper. Firstly, the principle of low-frequency oscillation in the power system is analyzed by using a single machine infinite bus system. Secondly, considering the dynamic characteristics of the ESS output active power, a controller for the ESS to suppress low-frequency oscillation is designed, which can provide positive damping for frequency oscillation of the power grid. Finally, the simulation analysis and experimental results of an actual weak grid are carried out to verify the effectiveness and feasibility of the proposed method. The results show that the suppression effect of the low-frequency oscillations is related to the ESS location in the weak power grid.
Investigation of key factors of Blackman-Harris window and interpolation algorithm in TTU frequency estimation module
Authors: Ge Yonggao , Wang Ning , Zhu Zujun 
Published: February 2022

Abstract
In order to provide a reference for the selection of related parameters when the Blackman-Harris window and interpolation algorithm is applied to the frequency estimation for voltage and current signals in transformer terminal unit (TTU), the principle of the algorithm is introduced, the implementation is preliminarily discussed, and the influence of signal parameters and measurement parameters on the frequency error is investigated based on the numerically generated voltage signals. The results reveal that the error is proportional to the frequency deviation of the signal. The frequency error decreases exponentially with signal-to-noise ratio (SNR) and sampling duration. Total harmonic distortion, sampling frequency and analog-to-digital converter (ADC) quantization bit have almost no impact on frequency error.
Research on the scheduling of unit operation mode for combined heat and power plants considering new energy consumption in heating season
Authors: Lin Chengkun , Song Jiwei , Wang Congyu 
Published: February 2022

Abstract
China aims to peak carbon dioxide emissions before 2030 and achieve carbon neutrality before 2060. The traditional coal power plants need to reduce theirs power load as much as possible to reduce CO2 emissions and improve the consumption capacity of intermittent renewable energy. Nevertheless, in part of northern China, areas with a high proportion of combined heat and power (CHP) units in coal power, CHP units need to provide heat load during heating season so that the flexibility of power load adjustment for CHP units is restricted. The plant minimum operation mode model is proposed to excavate the plant-level lower boundary of power load. By analysing the heat-power coupling mechanism of each unit, under different unit commitments, the plant-level lower boundary of power load can be calculated through dispatch heat load reasonably. Then the scheduling scheme of optimal unit commitment for plant is obtained. The comparison of results with the actual operation of a case CHP plant shows that the consumption capacity of renewable energy can be increased by 1.92 billion kWh and the CO2 emissions of the reference plant could be reduced by 52.5% under the scheduling scheme of optimal unit commitment during the heating season. The reduction of CO2 emissions for the scheduling scheme of optimal unit commitment will remain more carbon allowance which can bring revenue from carbon trade market. The scheduling of unit operation mode provides a way of operation under the current policy and environmental background, how to depress the power load of CHP plants and reduce CO2 emissions in heating season.
A fast frequency estimation algorithm and its application in transformer terminal unit
Authors: Li Cheng , Li Jun , Chen Zhiming 
Published: February 2022

Abstract
To accurately obtain the frequency of voltage and current signals and form the basis for the analysis of power quality in the Transformer Terminal Unit (TTU), a Hanning window and interpolation algorithm is proposed to estimate the signal frequency. The principle of the algorithm is introduced, and the computer program is written. At the same time, the voltage signals with different frequencies are numerically generated and the real voltage is measured, and the signal frequency is estimated by using the algorithm. The results reveal that the proposed method can accurately estimate the signal frequency for TTU, and the maximum error of frequency estimation is only 2 mHz when the signal frequency varies in the range of 49.8-50.2 Hz. However, the maximum error estimated by the FFT algorithm is up to 0.2 Hz. The computation time of the Hanning window and interpolation algorithm is only 1.29 times that of the Fast Fourier Transform algorithm. The work lays the foundation for accurate and rapid estimation of voltage and current signal frequency in TTU.
Modeling of large capacity condenser based on electromagnetic transient simulation and its impacts on East China Power Grid
Authors: Xie Hongping , Huang Tao , Zhao Weiguo , Sun Ke , Lin Dongyang , Huang Qinxin , Yang Mengmeng 
Published: February 2022

Abstract
With the development of long-distance transmission of higher voltage levels, the loss of reactive power on transmission lines is increasing. The dependence on the external electricity is also rising, so that the voltage stability problems of the receiving system have become increasingly prominent. Therefore, using dynamic reactive compensation technology can improve the operating characteristics of the power grid and improve the safety and stability of the system. Based on the electromagnetic transient data of East China Power Grid in 2025, based on the parameters of the new large-capacity synchronous condenser, the electromagnetic transient model of the synchronous condenser is established and simulated. The simulation results show that after the installation of synchronous condenser, the minimum voltage of ZP bus is improved to different extents, the voltage recovery time is reduced to different extents. It also plays a certain role in reducing the number of commutation failures. Therefore, the installation of the synchronous condenser can provide effective dynamic reactive support for the local power grid with high proportion of DC power, which can reduce the probability of DC commutation failure in the AC grid fault.
Experiment research of Al particle’s ignition and combustion characteristics of NEPE propellant
Authors: Xia Wenjie , Zhuang Yuqian , Cai Wenxiang , Xue Donglin , Cao Yanbang , Song Xiaodong 
Published: February 2022

Abstract
Based on optical photography analysis method, agglomeration process of Al particles at aluminized NEPE propellant’s surface, dynamic combustion process after leaving burning surface and the collision under different pressure of N2, were photographed by highspeed camera. MATLAB was used to deal with the images to analyze the size of agglomerated particles. Experiment research results showed that higher pressure was helpful for improving ignition performance and increasing combustion efficiency of the aluminized NEPE propellant. For the agglomeration products, dimension was reduced, size distribution became more uniform, and amount of the mass increased with higher pressure environment.
Research and system design of energy dynamic balance and optimal scheduling of iron and steel enterprises
Authors: Meng Hua , Huang Yi , Zheng Chunni , Zhou Ya , Chen Yanru 
Published: February 2022

Abstract
The steel industry is an important part of the secondary industry, and it has a strong role in promoting economic development. However, the steel industry is a high-energy-consuming industry, which has large energy consumption and waste of resources. Therefore, it is very important to do a good job of energy conservation and emission reduction in iron and steel enterprises. Therefore, this paper studies the dynamic energy balance and optimization model of iron and steel enterprises firstly, and further designs and operates the system based on this. It is show that the model has good practicability, which can balance the pipe network and reduce emission.
Geometry contributions to natural convection heat transfer enhancement by the chimney effect
Authors: Njoroge John , Gao Puzhen 
Published: February 2022

Abstract
Natural convection heat transfer enhancement continues to be an evolving problem in the design of passive safety systems in nuclear engineering. Increasing heat rejection rates guarantees safety and higher heat duty. This study numerically investigated the influence of the geometry of an adiabatic extension appended downstream of a vertical heated cylinder. Four geometries comprising straight, diffuse, hyperboloid, and compound adiabatic extensions were studied. Nusselt number ratios, temperature distribution ratios, and mass flow rates were presented. Results showed that the compound extension geometry exuded high heat transfer enhancement capabilities by the chimney effect, and reduced wall temperature by up to 16% for the range of parameters studied. These findings are presented as a contribution to the design improvements of air-cooled passive systems, especially in advanced nuclear reactors.
Pyrolysis characteristics, kinetics and thermodynamics of the plywood material in high-speed trains
Authors: Wei Lingling , Li Li , Qiu Tingting , Li Changhai , Lu Shouxiang 
Published: February 2022

Abstract
The pyrolysis characteristics, kinetics and thermodynamics of a typical plywood material, namely the Huangjinguomu plywood in high-speed trains in nitrogen were studied in the present study. It was indicated that three peaks occurred in the reaction rate curves. The pyrolysis process can be divided into three stages, namely stage 1: 0<a<0.1, stage 2: 0.1<a<0.7 and stage 3: 0.7<a<1. With the increase in the heating rate, the first and third peak reaction rate decreased, while the second peak reaction rate increased. The average reaction rate in stage 1 and throughout the entire pyrolysis process decreased. The average reaction rate in stage 2 increased. The average reaction rate in stage 3 remained almost constant. The second stage may be nominally considered to be a one-step reaction. The pyrolysis of the Huangjinguomu plywood was a non-spontaneous and endothermic process. The AG value maintained almost constant with the progressing of the thermal decomposition. The average values of AH, AG and AS were 191.55 kJ/mol, 139.29 kJ/mol and 92.93 J/(molK), respectively.
Current situation and trend analysis of electrification level of terminal energy consumption
Authors: Tang Wei , Zhang Yu 
Published: February 2022

Abstract
Under the background of carbon neutral, improving the level of terminal electrification can promote the use of clean energy and improve the efficiency of energy use, which is an important means to accelerate the low-carbon transformation of energy, promote the sustainable development of economy and society, and achieve the goal of “carbon peak, carbon neutral”. This paper analyzes the current situation of China’s terminal electrification level from different dimensions, analyzes the development trend of these factors, and forecasts the future terminal electrification level through qualitative analysis of influencing factors and data calculation.