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Numerical Simulation Study on Influence of Equation of State on Internal Flow Field and Performance of S-CO_(2)Compressor

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Journal of Thermal Science 2024年第3期33卷 888-898页

作者： ZHANG Lei YANG Zhenyu SUN Enhui ZHANG Qian AN Guangyao YUAN Wei Hebei Key Laboratory of Low Carbon and High Efficiency power Generation Technology North China Electric Power UniversityBaoding071003China School of Energy Power&Mechanical EngineeringNorth China Electric Power UniversityBaoding071028China

The low power consumption of the near-critical compressor is the key factor for the high efficiency of supercritical CO_(2)Brayton *** the numerical simulation of the compressor,the rapid changes in the thermophysical properties of the CO_(2)near the critical point make it difficult to capture the condensation *** paper investigates the influence of fluid physical properties on the condensation ***,the differences in the physical properties of CO_(2)in the SRK EOS(equation of state),PR EOS,and SW EOS are ***,the simulation of nozzles and compressors were carried out and *** show that the condensation positions predicted by the three EOSs are basically the *** with SW EOS,the disparities between the maximum condensation mass fraction predicted by the PR and SRK EOSs is5.7%and 11.5%,and that of total pressure ratio is 0.3%and 3.8%,*** results show that PR EOS can be considered for numerical simulation in engineering *** its physical property calculation results are closer to the actual physical properties while the physical properties change more gently,it has considerable accuracy and numerical stability.

关键词： supercritical carbon dioxide equation of state centrifugal compressor numerical simulation condensation

electricity Pricing with Continuous-time Commodity Model and Non-monotonic Load Curve

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CSEE Journal of power and Energy Systems 2024年第1期10卷 272-280页

作者： Lijia Han Yue Li Haoyong Chen Ningning Lu Mathematical and Physical Science School North China Electric Power UniversityBeijing 102206China School of electric power engineering South China University of TechnologyGuangzhou 510641China

Under the "carbon peak and carbon neutrality"background,clean energy enters the market on a large scale,so it is very important to study the pricing theory of *** bright spot of this paper is that the load curve is more *** the original version of electricity pricing theory based on continuous time commodity model,the load curve is supposed to be a monotonic function with time for simplicity of derivation,which is not *** overcome this defect,load curves are supposed to be in shapes of a unimodal model and multimodal cases in this paper,which are more in conformity with the actual load curve in real-world power *** study cases are used to demonstrate the rationality of the proposed *** results together with the authors'previous work provide a complete pricing scheme for continuous-time electricity commodity model.

关键词： Functional optimization market equilibrium spot pricing variational method

Quantum block coherence with respect to projective measurements

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Chinese Physics B 2024年第8期33卷 213-220页

作者：王璞李忠艳孟会贤 School of Control and Computer engineering North China Electric Power UniversityBeijing 102206China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China

Quantum coherence serves as a defining characteristic of quantum mechanics,finding extensive applications in quantum computing and quantum communication *** study explores quantum block coherence in the context of projective measurements,focusing on the quantification of such ***,we define the correlation function between the two general projective measurements P and Q,and analyze the connection between sets of block incoherent states related to two compatible projective measurements P and ***,we discuss the measure of quantum block coherence with respect to projective *** on a given measure of quantum block coherence,we characterize the existence of maximal block coherent states through projective *** research integrates the compatibility of projective measurements with the framework of quantum block coherence,contributing to the advancement of block coherence measurement theory.

关键词： quantum coherence compatibility projective measurement quantum block coherence

Finite Element Method for Transient electric Field by Using Indirect Laplace Transform with High Accuracy

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CSEE Journal of power and Energy Systems 2024年第1期10卷 401-411页

作者： Teng Wen Xiang Cui Xuebao Li Sijia Liu Zhibin Zhao State Key Laboratory of Alternate electrical power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China China electric power Planning&engineering Institute Beijing 100120China

This paper focuses on the finite element method in the complex frequency domain(CFD-FEM)for the transient electric ***,the initial value and boundary value problem of the transient electric field under the electroquasistatic field in the complex frequency domain is *** addition,the finite element equation and the constrained electric field equation on the boundary are ***,the indirect algorithm of the numerical inverse Laplace transform is *** on it,the calculation procedures of the CFD-FEM are illustrated in ***,the step response,zero-state response under the positive periodic square waveform(PPSW)voltage,and the zero-input response by the CFD-FEM with direct algorithm and indirect algorithm are ***,the reason for the numerical oscillations of the zero-state response under the PPSW voltage is analyzed,and the method to reduce oscillations is *** results show that the numerical accuracy of the indirect algorithm of the CFD-FEM is more than an order of magnitude higher than that of the direct algorithm when calculating the step response of the transient electric *** proposed method can significantly reduce the numerical oscillations of the zero-state response under the PPSW *** proposed method is helpful for the calculation of the transient electric field,especially in the case of frequency-dependent parameters.

关键词： Electroquasistatic field transient electric field finite element method complex frequency domain numerical Laplace transform

Pre-Training Physics-Informed Neural Network with Mixed Sampling and Its Application in High-Dimensional Systems

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Journal of Systems Science & Complexity 2024年第2期37卷 494-510页

作者： LIU Haiyi ZHANG Yabin WANG Lei School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China School of Control and Computer engineering North China Electric Power UniversityBeijing 102206China

Recently,the physics-informed neural network shows remarkable ability in the context of solving the low-dimensional nonlinear partial differential ***,for some cases of high-dimensional systems,such technique may be time-consuming and *** this paper,the authors put forward a pre-training physics-informed neural network with mixed sampling(pPINN)to address these *** based on the initial and boundary conditions,the authors design the pre-training stage to filter out the set of the misfitting points,which is regarded as part of the training points in the next *** authors further take the parameters of the neural network in Stage 1 as the initialization in Stage *** advantage of the proposed approach is that it takes less time to transfer the valuable information from the first stage to the second one to improve the calculation accuracy,especially for the high-dimensional *** verify the performance of the pPINN algorithm,the authors first focus on the growing-and-decaying mode of line rogue wave in the Davey-Stewartson I *** case is the accelerated motion of lump in the inhomogeneous Kadomtsev-Petviashvili equation,which admits a more complex evolution than the uniform *** exact solution provides a perfect sample for data experiments,and can also be used as a reference frame to identify the performance of the *** experiments confirm that the pPINN algorithm can improve the prediction accuracy and training efficiency well,and reduce the training time to a large extent for simulating nonlinear waves of high-dimensional equations.

关键词： High-dimensional systems mixed sampling nonlinear wave pre-training physics-informed neural network

P2P Energy Trading Considering Prosumer Preference and System Risk

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CSEE Journal of power and Energy Systems 2024年第3期10卷 1179-1194页

作者： Xinyu He Ping Dong Mingbo Liu Xuewei Huang Wenli Deng Ruijin He School of electric power engineering South China University of TechnologyGuangzhou 510640China IEEE

As an important means of mobilizing demand-side resources,peer-to-peer(P2P)energy trading has drawn more and more attention from *** paper constructs a P2P energy trading framework considering prosumers’trading partner preferences(TPPs)and system *** first,we build the P2P trading models of prosumers equipped with different distributed energy resources(DERs),and TPP ***,to solve the established energy trading problem,a fully distributed double-consensus alternating direction method of multipliers(DC-ADMM)is proposed,which can achieve transaction consensus when considering market players’***,a risk-based security constrained economic dispatch(RBSCED)model based on AC power flow is established for the first time,by which a distribution system operator(DSO)checks system security and obtains risk-based locational marginal prices(RLMPs).Moreover,double-regulated price signals related to RLMPs which contain grid utilization prices(GUPs)and DSO’s retail prices realize management of players’*** the end,the proposed method is applied to an IEEE33 bus distribution *** show the proposed method effectively reduces system risk and ensures secure operation of system without direct management.

关键词： Double-consensus ADMM grid utilization price price signal risk-based locational marginal price trading partner preference

A Hybrid Signal Processing Method Combining Mathematical Morphology and Walsh Theory for power Quality Disturbance Detection and Classification

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CSEE Journal of power and Energy Systems 2024年第2期10卷 584-592页

作者： Zhi Ding Tianyao Ji Mengshi Li Q.H.Wu School of electric power engineering South China University of Technology(SCUT)Guangzhou 510641China

In this paper, a novel signal processing method combining mathematical morphology (MM) and Walsh theory is proposed, which uses Walsh functions to control the structuring element (SE) and MM operators. Based on the Walsh-MM method, a scheme for power quality disturbances detection and classification is developed, which involves three steps: denoising, feature extraction and morphological clustering. First, various evolution rules of Walsh function are used to generate groups of SEs for the multiscale Walsh-ordered morphological operation, so the original signal can be denoised. Next, the fundamental wave of the denoised signal is suppressed by Hadamard matrix;thus, disturbances can be extracted. Finally, the Walsh power spectrum of the waveform extracted in the previous step is calculated, and the parameters of which are taken by morphological clustering to classify the disturbances. Simulation results reveal the proposed scheme can effectively detect and classify disturbances, and the Walsh-MM method is less affected by noise and only involves simple calculation, which has a potential to be implemented in hardware and more suitable for real-time application.

关键词： Hadamard matrix mathematical morphology morphological clustering power quality disturbance Walsh theory

Decision Aid Model for Private-owned electric Vehicles Participating in Frequency Regulation Ancillary Service Market

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Journal of Modern power Systems and Clean Energy 2024年第2期12卷 621-629页

作者： Liwei Wang Yingyun Sun Haotian Wang Pengfei Zhao Muhammad Safwan Jaffar School of electrical and Electronic engineering North China Electric Power UniversityBeijing 102206China

To reduce the difficulty and enhance the enthusiasm of private-owned electric vehicles(EVs) in participating in frequency regulation ancillary service market(FRASM), a decision aid model(DAM) is proposed. This paper presents three options for EV participating in FRASM, i. e., the base mode(BM), unidirectional charging mode(UCM), and bidirectional charging/discharging mode(BCDM), based on a reasonable simplification of users' participating willingness. In BM, individual EVs will not be involved in FRASM, and DAM will assist users to set the optimal charging schemes based on travel plans under the time-of-use(TOU) price. UCM and BCDM are two modes in which EVs can take part in FRASM. DAM can assist EV users to create their quotation plan, which includes hourly upper and lower reserve capabilities and regulation market mileage prices. In UCM and BCDM, the difference is that only the charging rate can be adjusted in the UCM, and the EVs in BCDM can not only charge but also discharge if necessary. DAM can estimate the expected revenue of all three modes, and EV users can make the final decision based on their preferences. Simulation results indicate that all the three modes of DAM can reduce the cost, while BCDM can get the maximum expected revenue.

关键词： electric vehicle(EV) frequency regulation decision aid model(DAM) utility maximization battery wear cost

Location of Asymmetric Ground Fault Using Virtual Injected Current Ratio and Two-stage Recovery Strategy in Distribution Networks

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CSEE Journal of power and Energy Systems 2024年第1期10卷 151-161页

作者： Haiting Shan Luliang Zhang Q.H.Wu Mengshi Li School of electric power engineering South China University of Technology(SCUT)Guangzhou 510641China

Sparse measurements challenge fault location in distribution *** paper proposes a method for asymmetric ground fault location in distribution networks with limited measurements.A virtual injected current vector is formulated to estimate the fault line,which can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).The relationship between the virtual injected current ratio(VICR)and fault position is deduced from circuit analysis to pinpoint the ***,a two-stage recovery strategy is proposed for improving reconstruction accuracy of the current vector,where two different sensing matrixes are utilized to improve the *** proposed method is validated in IEEE 34 node test *** results show asymmetric ground fault type,resistance,fault position and access of distributed generators(DGs)do not significantly influence performance of our *** addition,it works effectively under various scenarios of noisy measurement and line parameter *** on 134 node test feeders prove the proposed method is also suitable for systems with more complex structure.

关键词： Distribution networks fault location reconstruction accuracy two-stage recovery virtual injected current ratio