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CSEE Journal of power and Energy Systems 2022年第3期8卷 710-720页

作者： Lin Yu Huadong Sun Shiyun Xu Bing Zhao Jian Zhang state Key Laboratory of power grid Safety and Energy Conservation China Electric Power Research InstituteBeijing100192China

The power system is experiencing a higher penetration of renewable energy generations(REGs).The short circuit ratio(SCR)and the grid impedance ratio(GIR)are two indices to quantify the system strength of the power system with *** this paper,the critical short circuit ratio(CSCR)is defined as the corresponding SCR when the system voltage is in the critical stable *** static voltage stability analysis,the mathematical expression of the CSCR considering the impact of GIR is *** maximum value of CSCR is adopted as the critical value to distinguish the weak power *** on the static equivalent circuit analysis,it is proved that the CSCR is still effective to evaluate critical system strength considering the interactive impact among ***,we find that the GIR can be neglected and the SCR can be used individually to evaluate the system strength when SCR>2 or GIR>*** correctness and rationality of the CSCR and its critical value are validated on ADPSS.

关键词： Critical short circuit ratio critical value grid impedance ratio maximum power transfer theorem static equivalent circuit analysis

Infuences of Different Admixtures on the Drying Shrinkage Characteristics of Metakaolin-based Geopolymer Mortar

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Journal of Wuhan University of Technology(Materials Science) 2024年第6期39卷 1425-1433页

作者： ZHI Jing ZHANG Chengyang WANG Yunwen WEI Libao ZHANG Pan state grid gansu electric power Company Wuwei power Supply Company Wuwei 733000China state grid gansu electric power Company Baiyin power Supply Company Baiyin 730900China

To investigate the influences of different admixtures on the drying shrinkage of polymer mortar in a metakaolin base,the experiments of VAE(vinyl acetate ethylene copolymer),APAM(anionic polyacrylamide)and CPAM(cationic polyacrylamide)on the drying shrinkage properties of geopolymer mortar were designed under normal temperature curing *** SP-175 mortar shrinkage dilatometer was introduced to measure the dry shrinkage of geopolymer ***,the drying shrinkage properties of geopolymer mortar are exhibited by the parameters of water loss rate,drying shrinkage rate,drying shrinkage strain and drying shrinkage *** experimental data are further fitted to obtain the prediction model of dry shrinkage of geopolymer mortar,which can better reflect the relationship between dry shrinkage rate and ***,the experimental results demonstrate that the dry shrinkage of geopolymer mortar can be significantly increased by adding 4%VAE admixture,meanwhile under the condition that the polymer film formed by VAE reaction can strengthen and toughen the mortar.2.5%APAM admixture and 1.5%CPAM admixture can enhance the dry shrinkage performance of geopolymer mortar in a certain range.

关键词： metakaolin base polymer mortar dry shrinkage property admixture dry shrinkage prediction model

Experimental Study on Energy Storage Characteristics of Sintered Ore Particle Packed Beds

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Journal of Thermal Science 2025年第1期 242-253页

作者： LAI Zhenya DING Liwei LYU Hongkun HOU Chenglong CHEN Jiaying GUO Xutao HAN Gaoyan ZHANG Kang state grid Zhejiang electric power Research Institute state Key Laboratory of Clean Energy Utilization Zhejiang University

The particle packed bed energy storage system has advantages such as low costs and wide temperature ranges,which can be combined with solar thermal power generation systems to solve the inherent volatility and discontinuity of renewable *** new materials with low costs and excellent storage performances is one of the eternal research hotspots in the field of energy *** paper innovatively uses sintered ore particles as energy storage material and studies the effect of particle size on the airflow resistance characteristics,energy storage characteristics,and thermocline evolution characteristics of the packed bed through thermal energy storage *** results indicate that for the particles in the macro scale,the smaller the particle,the lower the absolute permeability of the bed and the greater the airflow *** packed bed with smaller particles has a larger specific surface area,larger bulk mass,and smaller bed ***,the packed beds with smaller particles have better thermocline characteristics,less irreversible loss,and can achieve higher thermal efficiency and higher exergy efficiency in the heat storage *** cycle thermal efficiency in packed beds with 25-40 mm,16-25 mm,and 10-16 mm particles is 53.58%,56.27%,and 57.60%,respectively,and the cycle exergy efficiency is 61.81%,69.25%,and 74.13%,***,this paper also studies the effect of discharging airflow rates on thermal storage *** experimental results indicate that suitable discharging strategies should be selected based on different heat demands.

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Multi-objective interval prediction of wind power based on conditional copula function

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Journal of Modern power Systems and Clean Energy 2019年第4期7卷 802-812页

作者： Gang ZHANG Zhixuan LI Kaoshe ZHANG Lei ZHANG Xia HUA Yongqing WANG Institute of Water Resources and Hydro-electric Engineering Xi’an University of TechnologyXi’an 710048China state grid Shaanxi Baoji electric power Company Baoji 721000China state grid gansu electric power Company Gansu Electric Power Research InstituteLanzhou 730050China state grid Shaanxi electric power Company Shaanxi Electric Power Research InstituteXi’an 710054China

Interval prediction of wind power,which features the upper and lower limits of wind power at a given confidence level,plays a significant role in accurate prediction and stability of the power grid integrated with wind ***,the conventional methods of interval prediction are commonly based on a hypothetic probability distribution function,which neglects the correlations among various variables,leading to the decrease of prediction ***,we improve the multi-objective interval prediction based on the conditional copula function,through which we can fully utilize the correlations among variables to improve prediction accuracy without an assumed probability distribution *** use the multi-objective optimization method of nondominated sorting genetic algorithm-II(NSGA-II)to obtain the optimal solution *** particular best solution is weighted by the prediction interval average width(PIAW)and prediction interval coverage probability(PICP)to pick the optimized solution in practical ***,we apply the proposed method to three wind power plants in different cities in China as examples forvalidation and obtain higher prediction accuracy compared with other methods,i.e.,relevance vector machine(RVM),artificial neural network(ANN),and particle swarm optimization kernel extreme learning machine(PSO-KELM).These results demonstrate the superiority and practicability of this method in interval prediction of wind power.

关键词： Wind power prediction Interval prediction Conditional copula function Empirical distribution function Multi-objective optimization algorithm

Wind power prediction based on variational mode decomposition multi-frequency combinations

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Journal of Modern power Systems and Clean Energy 2019年第2期7卷 281-288页

作者： Gang ZHANG Hongchi LIU Jiangbin ZHANG Ye YAN Lei ZHANG Chen WU Xia HUA Yongqing WANG Institute of Water Resources and Hydro-electric Engineering Xi’an University of TechnologyXi’an 710048China state grid gansu electric power Company Gansu Electric Power Research InstituteLanzhou 730050China state grid Shaanxi electric power Company Shaanxi Electric Power Research InstituteXi’an 710054China

Because of the uncertainty and randomness of wind speed, wind power has characteristics such as nonlinearity and multiple frequencies. Accurate prediction of wind power is one effective means of improving wind power integration. Because the traditional single model cannot fully characterize the fluctuating characteristics of wind power, scholars have attempted to build other prediction models based on empirical mode decomposition(EMD) or ensemble empirical mode decomposition(EEMD) to tackle this problem. However, the prediction accuracy of these models is affected by modal aliasing and illusive components. Aimed at these defects, this paper proposes a multi-frequency combination prediction model based on variational mode decomposition(VMD). We use a back propagation neural network(BPNN),autoregressive moving average(ARMA)model, and least square support vector machine(LS-SVM) to predict high, intermediate,and low frequency components,respectively. Based on the predicted values of each component, the BPNN is applied to combine them into a final wind power prediction ***,the prediction performance of the single prediction models(ARMA,BPNN and LS-SVM)and the decomposition prediction models(EMD and EEMD) are used to compare with the proposed VMD model according to the evaluation indices such as average absolute error, mean square error,and root mean square error to validate its feasibility and accuracy. The results show that the prediction accuracy of the proposed VMD model is higher.

关键词： Wind power prediction Variational mode decomposition Multi-frequency combination prediction Back propagation neural network Autoregressive moving average model Least square support vector machine

Optical Fibre Communication Feature Analysis and Small Sample Fault Diagnosis Based on VMD-FE and Fuzzy Clustering

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Energy Engineering 2024年第1期121卷 203-219页

作者： Xiangqun Li Jiawen Liang Jinyu Zhu Shengping Shi Fangyu Ding Jianpeng Sun Bo Liu Gannan power Supply Company of state grid gansu electric power Supply Company Hezuo747000China Digital Communication Department Gannan Power Supply Company of State Grid Gansu Electric Power Supply CompanyHezuo747000China

To solve the problems of a few optical fibre line fault samples and the inefficiency of manual communication optical fibre fault diagnosis,this paper proposes a communication optical fibre fault diagnosis model based on variational modal decomposition(VMD),fuzzy entropy(FE)and fuzzy clustering(FC).Firstly,based on the OTDR curve data collected in the field,VMD is used to extract the different modal components(IMF)of the original signal and calculate the fuzzy entropy(FE)values of different components to characterize the subtle differences between *** fuzzy entropy of each curve is used as the feature vector,which in turn constructs the communication optical fibre feature vector matrix,and the fuzzy clustering algorithm is used to achieve fault diagnosis of faulty optical *** VMD-FE combination can extract subtle differences in features,and the fuzzy clustering algorithm does not require sample *** experimental results show that the model in this paper has high accuracy and is relevant to the maintenance of communication optical fibre when compared with existing feature extraction models and traditional machine learning models.

关键词： Optical fibre fault diagnosis OTDR curve variational mode decomposition fuzzy entropy fuzzy clustering

Influence characteristics of water penetration on fibre-reinforced polymer/rigid polyurethane foam interface of the composite cross-arm considering natural ageing

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High Voltage 2024年第1期9卷 81-93页

作者： Jun Xie Zhe Zhou Ziqian Liu Haonan Tian Sigang Zhang Qing Xie Hebei Provincial Key Laboratory of power Transmission Equipment Security Defense North China Electric Power UniversityBaodingChina state grid gansu electric power Company LanzhouChina

Fibre-reinforced polymer(FRP)/rigid polyurethane foam(RPUF)interface is susceptible to moisture intrusion in addition to natural ageing during *** study investigated the influence of moisture intrusion on the FRP/RPUF interface under natural ageing using experiments and molecular dynamics(MD)*** absorption,shear strength,and leakage current tests were used to clarify the changes in the interface *** degradation mechanism of moisture intrusion at the interface under natural ageing was revealed by MD simulation and *** results show that the natural ageing of interfacial materials will slightly reduce the quality of the interface but will reduce the water resistance of the material and promote the process of water intrusion into the *** addition,water mainly invades the interface through *** water penetration,the interfacial bonding strength and insulation performance significantly *** and hydrolysis of interfacial materials are the main reasons for decreased interfacial *** can cause irreversible damage to the interface,increasing interface defects and water *** vicious cycle of material hydrolysis is the ultimate cause of interfacial *** polar molecules produced by this process and the water absorbed by the interface caused the degradation of the interface insulation performance.

关键词： interface polyurethane interfacial

Subsynchronous resonance and its mitigation for power system with unified power flow controller

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Journal of Modern power Systems and Clean Energy 2018年第1期6卷 181-189页

作者： Xinyao ZHU Meng JIN Xiangping KONG Jingbo ZHAO Jiankun LIU Qian ZHOU state grid Jiangsu electric power Research Institute state grid Jiangsu electric power Maintenance Branch Company

Control strategy of unified power flow controller(UPFC)utilizing dq decoupling control is deduced in this paper,which can closely follow the control orders of the active and reactive *** subsynchronous resonance(SSR)characteristics of a series compensated system equipped with UPFC are studied,and the results reveal that SSR characteristics of the system may vary significantly with UPFC in service or ***,supplementary subsynchronous damping controller(SSDC)for UPFC is proposed and investigated,and the effectiveness of the proposed SSDC is verified by damping torque analysis and time domain simulations.

关键词： Unified power flow controller(UPFC) Series capacitor compensation Subsynchronous resonance(SSR) Supplementary subsynchronous damping controller(SSDC) Damping torque analysis

Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

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Plasma Science and Technology 2014年第8期16卷 749-757页

作者：刘兴华咸日常孙学峰王涛吕学宾陈素红杨帆 state grid Zibo power Supply Company state grid Shandong electric power Company state grid Shandong electric power Research Institute state Key Laboratory of power Transmission Equipment & System Security and New Technology Chongqing University

Investigating the corona mechanism plays a key role in enhancing the performance of electrical insulation systems. Numerical simulation offers a better understanding of the physical characteristics of air corona discharges. Using a two-dimensional axisymmetrical kinetics model, into which the photoionization effect is incorporated, the DC air corona discharge at atmosphere pressure is studied. The plasma model is based on a self-consistent, multi-component, and con- tinuum description of the air discharge, which is comprised of 12 species and 22 reactions. The discharge voltage-current characteristic predicted by the model is found to be in quite good agree- ment with experimental measurements. The behavior of the electronic avalanche progress is Mso described. 0＋ and N＋ are the dominant positive ions, and the values of 0- and 02 densities are much smaller than that of the electron. The electron and positive ion have a low-density thin layer near the anode, which is a result of the surface reaction and absorption effect of the electrode. As time progresses, the electric field increases and extends along the cathode surface, whereas the cathode fall shrinks after the corona discharge hits the cathode; thus, in the cathode sheath, the electron temperature increases and the position of its peak approaches to the cathode. The present computational model contributes to the understanding of this physical mechanism, and suggests ways to improve the electrical insulation system.

关键词： air corona discharge atmospheric pressure numerical simulation mechanism

Energy Economic Dispatch for Photovoltaic-Storage via Distributed Event-Triggered Surplus Algorithm

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Energy Engineering 2024年第9期121卷 2621-2637页

作者： Kaicheng Liu Chen Liang Naiyue Wu Xiaoyang Dong Hui Yu China electric power Research Institute Beijing100192China electric power Research Institute of state grid gansu electric power Company Lanzhou730000China state Key Laboratory of power grid Safety Beijing100084China

This paper presents a novel approach to economic dispatch in smart grids equipped with diverse energy *** method integrates features including photovoltaic(PV)systems,energy storage coupling,varied energy roles,and energy supply and demand *** systemmodel is developed by considering energy devices as versatile units capable of fulfilling various functionalities and playing multiple roles *** strike a balance between optimality and feasibility,renewable energy resources are modeled with considerations for forecasting errors,Gaussian distribution,and penalty ***,this study introduces a distributed event-triggered surplus algorithm designed to address the economic dispatch problem by minimizing production *** in surplus theory and finite time projection,the algorithm effectively rectifies network imbalances caused by directed graphs and addresses local inequality *** algorithm greatly reduces the communication burden through event triggering ***,both theoretical proofs and numerical simulations verify the convergence and event-triggered nature of the algorithm.

关键词： Fully distributed algorithm economic dispatch directed graph renewable energy resource