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Isotopic dependence of the yield ratios of light fragments from different projectiles and their unified neutron skin thicknesses

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Nuclear Science and Techniques 2024年第3期35卷 228-236页

作者： Ting-Zhi Yan Shan Li school of Energy and power engineering Northeast Electric Power UniversityJilin 132012China

The yield ratios of neutron-proton(R(n/p))and^(3)H-^(3)He(R(^(3)H∕^(3)He))with reduced rapidity from 0 to 0.5 were simulated at 50 MeV/u even-even ^(36−56)Ca+^(40)Ca,even-even ^(48−78)Ni+^(58)Ni,and ^(100−139)Sn(every third isotopes)+112 Sn for full reduced impact parameters using the isospin-dependent quantum molecular dynamics(IQMD)model.The neutron and proton density distributions and root-mean-square radii of the reaction systems were obtained using the Skyrme-Hartree-Fock model,which was used for the phase space initialization of the projectile and target in IQMD.We defined the unified neutron skin thickness asΔRnp=^(1∕2) n−^(1∕2)p,which was negative for neutron-deficient nuclei.The unifiedΔRnp values for nuclei with the same relative neutron excess from different isotopic chains were nearly equal,except for extreme neutron-rich isotopes,which is a type of scaling behavior.The yield ratios of the three isotopic chain-induced reactions,which depended on the reduced impact parameter and unified neutron skin thickness,were studied.The results showed that both R(n/p)and R(^(3)H∕^(3)He)decreased with a reduced impact parameter for extreme neutron-deficient isotopes;however,they increased with reduced impact parameters for extreme neutron-rich isotopes,and increased with theΔRnp of the projectiles for all reduced impact parameters.In addition,a scaling phenomenon was observed betweenΔR np and the yield ratios in peripheral colli-sions from different isotopic chain projectiles(except for extreme neutron-rich isotopes).Thus,R(n/p)and R(^(3)H∕^(3)He)from peripheral collisions were suggested as experimental probes for extracting the neutron or proton skin thicknesses of non-extreme neutron-rich nuclei from different isotopic chains.

关键词： Exotic nuclei Unified neutron skin thickness Yield ratios IQMD

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Optimized Auxiliary Frequency Control of Wind Farm Based on Piecewise Reduced-order Frequency Response Model

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Journal of Modern power Systems and Clean Energy 2024年第3期12卷 791-802页

作者： Xu Zhang Chen Zhao Junchao Ma Long Zhang Dan Sun Chenxu Wang Yan Peng Heng Nian the school of electrical engineering Zhejiang University electric power Research Institute of State Grid Zhejiang electric power Corporation

With the increasing wind power penetration in the power system, the auxiliary frequency control(AFC) of wind farm(WF) has been widely used. The traditional system frequency response(SFR) model is not suitable for the wind power generation system due to its poor accuracy and applicability. In this paper, a piecewise reduced-order frequency response(PROFR) model is proposed, and an optimized auxiliary frequency control(O-AFC) scheme of WF based on the P-ROFR model is proposed. Firstly, a full-order frequency response model considering the change in operating point of wind turbine is established to improve the applicability. In order to simplify the fullorder model, a P-ROFR model with second-order structure and high accuracy at each frequency response stage is proposed. Based on the proposed P-ROFR model, the relationship between the frequency response indexes and the auxiliary frequency controller coefficients is expressed explicitly. Then, an OAFC scheme with the derived explicit expression as the optimization objective is proposed in order to improve the frequency support capability on the premise of ensuring the full release of the rotor kinetic energy and the full use of the effect of time delay on frequency regulation. Finally, the effectiveness of the proposed P-ROFR model and the performance of the proposed OAFC scheme are verified by simulation studies.

关键词： Frequency control Frequency response Rotors Analytical models Indexes Optimization Delay effects

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Thermodynamic and Economic Analysis of a Conceptual System Combining Sludge Gasification,SOFC,Supercritical CO2 Cycle,and Organic Rankine Cycle

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Journal of Thermal Science 2024年第4期33卷 1491-1508页

作者： LV Jiayang WANG Chizhong CHEN Heng PAN Peiyuan XU Gang ZHANG Guoqiang school of Energy Power and Mechanical EngineeringNorth China Electric Power University

In order to reduce the environmental impact of conventional sludge treatment methods and to utilize the energy in sludge more effectively,a coupled system based on sewage sludge gasifier（SSG）,solid oxide fuel cells（SOFC）,supercritical CO2cycle（S-CO2）,and organic Rankine cycle（ORC） is proposed.The clean syngas obtained from sludge gasification is mixed with CH4 and then first utilized by the fuel cell.The exhaust gas from the fuel cell is fully combusted in the afterburning chamber and then enters the bottom cycle system consisting of S-CO2& ORC to generate electricity.To understand the performance of the system,thermodynamic and economic analyses were conducted to examine the project's performance.The thermodynamics as well as the economics of the coupled system were analyzed to arrive at the following conclusions,the power production of the system is 37.34 MW;the exergy efficiency is 55.62%,and the net electrical efficiency is 61.48%.The main exergy destruction is the gasifier and SOFC,accounting for 62.45% of the total exergy destruction.It takes only6.13 years to repay the construction investment in the novel system,and the project obtains a NPV of 17 723 820USD during 20 years lifetime.The above findings indicate that the new coupled system has a better performance in terms of energy utilization and economy.

关键词： sewage sludge gasifier SOFC supercritical CO 2 cycle organic Rankine cycle multi-system coupling

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Research on Modeling and Parameter Identification of Comprehensive Load Model of Distribution Network in Industrial Park

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Chinese Journal of Electronics 2024年第1期33卷 264-273页

作者： Tingling WANG Xiaohe YAN school of electric engineering North China University of Water Resources and Electric Power Wenzhou Polytechnic

With the rapid development of industrial parks, its load model research has become a hot spot. In order to study the load of power system in industrial park, based on the characteristics of the industrial park load, a comprehensive load admittance static model with full voltage range adaptability is considered, and a comprehensive load model of distribution network of the industrial park is established. A complete parameter identification of the model is carried out through chaos particle swarm optimization. The simulation results show that the model can effectively describe the load characteristics of the distribution network in industrial parks.

关键词： Industrial park Comprehensive load model Distribution network Chaos particle swarm optimization

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Network Embedding Algorithm for Vulnerability Assessment of power Transmission Lines Using Integrated Structure and Attribute Information

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CSEE Journal of power and Energy Systems 2024年第1期10卷 351-360页

作者： Xianglong Lian Tong Qian Zepeng Li Xingyu Chen Wenhu Tang Q.H.Wu school of electric power engineering South China University of TechnologyGuangzhou 510640China

In power systems,failures of vulnerable lines can trigger large-scale cascading failures,and vulnerability assessment is dedicated to locating these lines and reducing the risks of such failures.Based on a structure and attribute network embedding(SANE)algorithm,a novel quantitative vulnerability analysis method is proposed to identify vulnerable lines in this research.First,a two-layered random walk network with topological and electrical properties of transmission lines is established.Subsequently,based on the weighted degree of nodes in the two-layered network,the inter-layer and intra-layer walking transition probabilities are developed to obtain walk sequences.Then,a Word2Vec algorithm is applied to obtain lowdimension vectors representing transmission lines,according to obtained walk sequences for calculating the vulnerability index of transmissions lines.Finally,the proposed method is compared with three widely used methods in two test systems.Results show the network embedding based method is superior to those comparison methods and can provide guidance for identifying vulnerable lines.

关键词： Network embedding random walk transmission lines vulnerability assessment

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Transitional Revenue Scheme for High-cost Generator Unit in Guangdong electricity Market Based on Government Authorized Contracts

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CSEE Journal of power and Energy Systems 2024年第1期10卷 208-221页

作者： Jisong Zhu Baike Chen Tianyao Ji Zhaoxia Jing school of electric power engineering South China University of TechnologyGuangzhou 510640China

High-cost generator units are at a cost disadvantage in electricity spot markets.This study focuses on revenue mechanisms of gas-fired units affected by power market reform in Guangdong province,China.For the first time,we compare impacts on market indicators of five settlement mechanisms:feed-in tariff(FiT),location marginal price(LMP),contract for difference(CFD),direct subsidy(DS),and estimated revenue method(ERM).In particular,we design key parameters,including authorized CFD and ERM of two kinds of government authorized contracts based on traditional dispatching patterns to avoid significant profit fluctuations brought by market reforms.We also analyze impact of factors such as climbing performance,seasonal load,and subsidy amount on the overall market and its players.Results of a case study show to directly subsidize gasfired units will lead higher-cost units to generate more electricity,with a resulting loss of social welfare.Disruption of market prices and provision of unreasonable incentives are fatal disadvantages of this subsidy method.The government and policymakers should consider financial means to adjust benefits to reduce production costs and increase social welfare.Also,by case analysis,the ERM shows its stable performance in revenue of high-cost units,while we find that authorized CFD is not applicable for gas-fired units whose output is unstable as a marginal unit frequently.Therefore,we suggest government agencies adopt ERM to sign contracts with gas-fired units,to attain a balance between fairness and efficiency.

关键词： Guangdong electricity market high-cost generator unit settlement mechanism subsidy

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Convexification of Hybrid AC-DC Optimal power Flow with Line-Commutated Converters

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CSEE Journal of power and Energy Systems 2024年第2期10卷 617-628页

作者： Hongyuan Liang Zhigang Li J.H.Zheng Q.H.Wu school of electric power engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based high-voltage DC (HVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

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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 electricity.The bright spot of this paper is that the load curve is more practical.In 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 realistic.To 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 markets.Two study cases are used to demonstrate the rationality of the proposed models.These 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

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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 equations.However,for some cases of high-dimensional systems,such technique may be time-consuming and inaccurate.In this paper,the authors put forward a pre-training physics-informed neural network with mixed sampling(pPINN)to address these issues.Just 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 stage.The authors further take the parameters of the neural network in Stage 1 as the initialization in Stage 2.The 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 systems.To 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 equation.Another case is the accelerated motion of lump in the inhomogeneous Kadomtsev-Petviashvili equation,which admits a more complex evolution than the uniform equation.The exact solution provides a perfect sample for data experiments,and can also be used as a reference frame to identify the performance of the algorithm.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

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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 scholars.This paper constructs a P2P energy trading framework considering prosumers’trading partner preferences(TPPs)and system risk.At first,we build the P2P trading models of prosumers equipped with different distributed energy resources(DERs),and TPP models.Secondly,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’TPPs.Then,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’transactions.In the end,the proposed method is applied to an IEEE33 bus distribution system.Results 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

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