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Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

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Petroleum Science 2024年第2期21卷 1275-1289页

作者： Qian Li Zi-Jie Lin Liu Yang Yue Wang Yue Li Wei-Hua Cai Laboratory of Thermo-Fluid Science and Nuclear Engineering Northeast Electric Power UniversityJilin132000JilinChina School of Energy and power Engineering Northeast Electric Power UniversityJilin132000JilinChina

The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 *** simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow *** results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were *** calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So hea

关键词： Printed circuit heat exchanger Vaporization Supercritical methane Pseudo-boiling Micro segment analysis

An Algorithm for Short-Circuit Current Interval in Distribution Networks with Inverter Type Distributed generation Based on Affine Arithmetic

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Energy Engineering 2024年第7期121卷 1903-1920页

作者： Yan Zhang Bowen Du Benren Pan GuannanWang Guoqiang Xie Tong Jiang electric power Research Institute State Grid Jiangxi Electric Power Co.Ltd.Nanchang330096China School of electrical and Electronic Engineering North China Electric Power UniversityBeijing102206China

During faults in a distribution network,the output power of a distributed generation(DG)may be ***,the output currents of distributed power sources are also affected by the output power,resulting in uncertainties in the calculation of the short-circuit current at the time of a ***,the impacts of such uncertainties around short-circuit currents will increase with the increase of distributed power ***,it is very important to develop a method for calculating the short-circuit current while considering the uncertainties in a distribution *** this study,an affine arithmetic algorithm for calculating short-circuit current intervals in distribution networks with distributed power sources while considering power fluctuations is *** proposed algorithm includes two *** the first stage,normal operations are considered to establish a conservative interval affine optimization model of injection currents in distributed power *** by the fluctuation range of distributed generation power at the moment of fault occurrence,the model can then be used to solve for the fluctuation range of injected current amplitudes in distributed power *** second stage is implemented after a malfunction *** this stage,an affine optimization model is first *** model is developed to characterizes the short-circuit current interval of a transmission line,and is constrained by the fluctuation range of the injected current amplitude of DG during normal ***,the range of the short-circuit current amplitudes of distribution network lines after a short-circuit fault occurs is *** algorithm proposed in this article obtains an interval range containing accurate results through interval *** with traditional point value calculation methods,interval calculation methods can provide more reliable analysis and calculation *** range of short-circuit current amplitude ob

关键词： Short circuit calculation inverter type distributed power supplies affine arithmetic distribution network

Plasma potential measurements using an emissive probe made of oxide cathode

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Chinese Physics B 2024年第4期33卷 571-577页

作者：李建泉马海杰陆文琪 department of Electronic and Communication Engineering North China Electric Power UniversityBaoding 071003China Hebei Key Laboratory of power Internet of Things Technology North China Electric Power UniversityBaoding 071003China Key Laboratory of Materials Modification by Laser Ion and Electron BeamsSchool of PhysicsDalian University of TechnologyDalian 116024China

A novel emissive probe consisting of an oxide cathode coating is developed to achieve a low operating temperature and long service *** properties of the novel emissive probe are investigated in detail,in comparison with a traditional tungsten emissive probe,including the operating temperature,the electron emission capability and the plasma potential *** of the operating temperature and electron emission capability show that the tungsten emissive probe usually works at a temperature of 1800 K-2200 K while the oxide cathode emissive probe can function at about 1200 K-1400 *** addition,plasma potential measurements using the oxide cathode emissive probe with different techniques have been accomplished in microwave electron cyclotron resonance plasmas with different discharge *** is found that a reliable plasma potential can be obtained using the improved inflection point method and the hot probe with zero emission limit method,while the floating point method is invalid for the oxide cathode emissive probe.

关键词： emissive probe oxide cathode plasma potential filament temperature

Equivalent Impedance Parameter Calculation of Three-phase Symmetrical Loads for Harmonic Source Location

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Journal of Modern power Systems and Clean Energy 2024年第1期12卷 251-260页

作者： Yi Zhang Bijie Liu Caihua Lin Zhenguo Shao Yuncong Xu the department of electrical Engineering and Automation Fuzhou UniversityFuzhouChina State Grid Fujian electric power Research Institute FuzhouChina

The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic ***,the existing calculation methods suffer from outliers caused by the zero-crossing of the *** outliers can result in inaccuracy and unreliability of harmonic source *** address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid *** correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring *** results show that the proposed method is not only simple and easy to implement but also highly accurate.

关键词： abc-αβtransformation equivalent impedance parameters of load harmonic source location nonlinear load power quality

Sparse Adversarial Learning for FDIA Attack Sample generation in Distributed Smart

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2095-2115页

作者： Fengyong Li Weicheng Shen Zhongqin Bi Xiangjing Su College of Computer Science and Technology Shanghai University of Electric PowerShanghai201306China College of electrical Engineering Shanghai University of Electric PowerShanghai201306China

False data injection attack(FDIA)is an attack that affects the stability of grid cyber-physical system(GCPS)by evading the detecting mechanism of bad *** FDIA detection methods usually employ complex neural networkmodels to detect FDIA ***,they overlook the fact that FDIA attack samples at public-private network edges are extremely sparse,making it difficult for neural network models to obtain sufficient samples to construct a robust detection *** address this problem,this paper designs an efficient sample generative adversarial model of FDIA attack in public-private network edge,which can effectively bypass the detectionmodel to threaten the power grid system.A generative adversarial network(GAN)framework is first constructed by combining residual networks(ResNet)with fully connected networks(FCN).Then,a sparse adversarial learning model is built by integrating the time-aligned data and normal data,which is used to learn the distribution characteristics between normal data and attack data through iterative ***,we introduce a Gaussian hybrid distributionmatrix by aggregating the network structure of attack data characteristics and normal data characteristics,which can connect and calculate FDIA data with normal ***,efficient FDIA attack samples can be sequentially generated through interactive adversarial *** simulation experiments are conducted with IEEE 14-bus and IEEE 118-bus system data,and the results demonstrate that the generated attack samples of the proposed model can present superior performance compared to state-of-the-art models in terms of attack strength,robustness,and covert capability.

关键词： Distributed smart grid FDIA adversarial learning power public-private network edge

Detection of Nonlinear Behavior Induced by Hard Limiting in Voltage Source Converters in Wind Farms Based on Higher-order Spectral Analysis

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Journal of Modern power Systems and Clean Energy 2024年第2期12卷 630-645页

作者： Zetian Zheng Shaowei Huang Qiangsheng Bu Chen Shen Jun Yan State Key Laboratory of power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China State Grid Jiangsu electric power Co. Ltd.Research InstituteNanjingChina

In recent years, sub-synchronous oscillation accidents caused by wind power integration have received extensive attention. The recorded constant-amplitude waveforms can be induced by either linear or nonlinear oscillation mechanisms. Hence, the nonlinear behavior needs to be distinguished prior to choosing the analysis method. Since the 1960s, the higher-order statistics(HOS) theory has become a powerful tool for the detection of nonlinear behavior(DNB) in production quality control wherein it has mainly been applied to mechanical condition monitoring and fault diagnosis. This study focuses on the hard limiters of the voltage source converter(VSC) control systems in the wind farms and attempts to detect the nonlinear behavior caused by bi-or uni-lateral saturation hard limiting using the HOS analysis. First, the conventional describing function is extended to obtain the detailed frequency domain information on the bi-and uni-lateral saturation hard limiting. Furthermore, the bi-and tri-spectra are introduced as the HOS, which are extended into bi-and tri-coherence spectra to eliminate the effects of the linear parts on the harmonic characteristics of hard limiting in the VSC control system, respectively. The effectiveness of the HOS in the DNB and the classification of the hard-limiting types is proven, and its detailed derivation and estimation procedure is presented. Finally, the quadratic and cubic phase coupling in the signals is illustrated, and the performance of the proposed method is evaluated and discussed.

关键词： Bi-coherence spectrum detection of nonlinear behavior hard limiting higher-order statistics tri-coherence spectrum voltage source converter wind farms.

Study on the influence of mechanism dispersion on transient recovery voltage distribution of modular DC vacuum circuit breakers

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High Voltage 2024年第2期9卷 346-355页

作者： Chongyang Huang Yongshuai Yin Shuxin Liu Hanwen Du Zengyu Shan Yundong Cao Shurui Yang Key Laboratory of Special electric Machines and High Voltage Apparatus in the Ministry of Education Shenyang University of TechnologyShenyangChina Shenyang power Supply Company of State Grid Liaoning electric power Co. LtdShenyangChina Chifeng power Supply Company of State Grid Mongolia electric power Co. LtdChifengChina

A simulation analysis and an experiment are carried out to investigate how the gap difference between the breaks of a direct current vacuum circuit breakers with multi-breaks(MB-DC VCB)caused by the mechanism dispersion of the breaker influences the distribution of TRV among the *** interruption model of MB-DC VCB,combining the continuous transition model,is established to analyse the rising rate of transient recovery voltage and the dielectric strength recovery speed of the breaks for MB-DC VCB under different gap difference *** on the experimental platform of dual break DC vacuum circuit breaker breaking,the correctness of the simulation model is verified on a DC VCB with the double-breaks interruption experimental ***,a model is applied to the non-synchronous interruption simulation of a DC VCB with *** relationship between the TRVs of the breaks under different gap difference conditions is analysed using the comparative analysis method,obtaining the maximum gap difference at the moment of breaking *** results of this study show that large-gap breaks have a higher TRV than small-gap breaks(the fracture of the action delay module),with double fractures reaching 1.4 times and triple fractures reaching a maximum of 1.52 times;the ability of small-gap breaks to withstand TRV is weak,giving rise to re-breakdown or even interruption failure;as the number of fractures increases,the maximum gap difference also *** the synchronous interruption ability of the MB-DC VCB is conducive to improving the interruption performance and interruption success rate of this type of a circuit breaker.

关键词： TRV transient distribution

Comprehensive Exergoeconomic Analysis and Optimization of a Novel Zero-Carbon-Emission Multi-generation System based on Carbon Dioxide Cycle

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Journal of Thermal Science 2024年第3期33卷 1065-1081页

作者： SUN Yan LI Hongwei WANG Di DU Changhe School of Energy and power Engineering Northeast Electric Power UniversityJilin132012China School of Automation Engineering Northeast Electric Power UniversityJilin132012China Xi’an Institute of Electromechanical Information Technology Xi’an710065China

This paper aims to conduct a comprehensive exergoeconomic analysis of a novel zero-carbon-emission multi-generation system and propose a fast optimization method combined with machine *** detailed exergoeconomic analysis of a novel combined power,freshwater and cooling multi-generation system is performed in this *** exergoeconomic analysis model is established by exergy flow theory.A comprehensive exergy,exergoeconomic and environmental analysis is carried *** critical decision variables are researched to bring out effects on the multi-generation system exergoeconomic performance.A novel fast optimization method combining genetic algorithm and Bagging neural network is *** advanced nature comparison is made between the proposed system and four similar *** display that increasing the turbine inlet temperature can improve exergy efficiency and decrease the total product unit *** multi-generation system exergy destruction directly determines exergy efficiency and total exergy destruction cost *** total product unit cost in the cost optimal design case is reduced by 7.7%and 25%,respectively,compared with exergy efficiency optimal design case and basic design *** with four similar cases,the proposed multi-generation system has great advantages in thermodynamic performance and exergoeconomic *** paper can provide research methods and ideas for performance analysis and fast optimization of multi-generation system.

关键词： waste heat recovery exergoeconomic analysis supercritical carbon dioxide optimization machine learning

Two-Stage Planning of Distributed power Supply and Energy Storage Capacity Considering Hierarchical Partition Control of Distribution Network with Source-Load-Storage

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Energy Engineering 2024年第9期121卷 2389-2408页

作者： Junhui Li Yuqing Zhang Can Chen Xiaoxiao Wang Yinchi Shao Xingxu Zhu Cuiping Li Key Laboratory of Modern power System Simulation and Control&Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin132012China State Grid Jibei electric power Co. Ltd.Electric Power Research InstituteBeijing100045China

Aiming at the consumption problems caused by the high proportion of renewable energy being connected to the distribution network,it also aims to improve the power supply reliability of the power system and reduce the operating costs of the power *** paper proposes a two-stage planning method for distributed generation and energy storage systems that considers the hierarchical partitioning of ***,an electrical distance structural index that comprehensively considers active power output and reactive power output is proposed to divide the distributed generation voltage regulation domain and determine the access location and number of distributed power ***,a two-stage planning is carried out based on the zoning *** the phase 1 distribution network-zoning optimization layer,the network loss is minimized so that the node voltage in the area does not exceed the limit,and the distributed generation configuration results are initially determined;in phase 2,the partition-node optimization layer is planned with the goal of economic optimization,and the distance-based improved ant lion algorithm is used to solve the problem to obtain the optimal distributed generation and energy storage ***,the IEEE33 node systemwas used for *** results showed that the voltage quality was significantly improved after optimization,and the overall revenue increased by about 20.6%,verifying the effectiveness of the two-stage planning.

关键词： Zoning control two-stage planning site selection and capacity determination optimized scheduling improved ant lion algorithm