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state Key Laboratory of power grid Safety and Energy Conservation,China electric power Research Institute,Beijing,China

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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

Investigating Periodic Dependencies to Improve Short-Term Load Forecasting

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Energy Engineering 2024年第3期121卷 789-806页

作者： Jialin Yu Xiaodi Zhang Qi Zhong Jian Feng state grid zhejiang Jiaxing electric power Co. Ltd.Jiaxing314000China state grid zhejiang electric power Co. Ltd.Hangzhou310000China

With a further increase in energy flexibility for customers,short-term load forecasting is essential to provide benchmarks for economic dispatch and real-time alerts in power *** electrical load series exhibit periodic patterns and share high associations with metrological ***,current studies have merely focused on point-wise models and failed to sufficiently investigate the periodic patterns of load series,which hinders the further improvement of short-term load forecasting ***,this paper improved Autoformer to extract the periodic patterns of load series and learn a representative feature from deep decomposition and *** addition,a novel multi-factor attention mechanism was proposed to handle multi-source metrological and numerical weather prediction data and thus correct the forecasted electrical *** paper also compared the proposed model with various competitive *** the experimental results reveal,the proposed model outperforms the benchmark models and maintains stability on various types of load consumers.

关键词： Load forecasting transformer attention mechanism power grid

Design of a 35 kV high-temperature superconducting synchronous machine with optimized field winding

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Journal of zhejiang University-Science A(Applied Physics & Engineering) 2024年第9期25卷 687-700页

作者： Chao LUO Bowen XU Jien MA Jiancheng ZHANG Jiabo SHOU Youtong FANG College of electrical Engineering Zhejiang UniversityHangzhou 310027China electric power Research Institute of state grid zhejiang electric power Corporation Hang Zhou 310014China

This paper proposes the application of high-voltage stator-cable windings in superconducting machines,based on the characteristics of strong magnetic fields and large air ***-linked polyethylene cable winding can be employed to achieve a rated voltage of 35 kV in direct-current(DC)-field superconducting machines,thereby enabling a direct connection between the superconducting machine and the power grid,eliminating the need for *** first,through finite element analysis,demonstrate that the proposed high-voltage high-temperature superconducting machine not only meets the requirement of a 35 kV-rated voltage,but also exhibits minimal flux leakage,torque fluctuation,and harmonic *** then compare three candidate types to discuss the tradeoff between the multi-group superconducting field winding arrangement and machine *** propose inverted trapezoidal superconducting field winding as a promising candidate,because it has minimal superconductivity material usage,the largest safety margin for the superconducting coils(SCs),low thrust ripple,and low total harmonic distortion with the desired 35 kV-rated ***,through large-scale design parameter sweeping,we show how we selected the optimal parameters for field winding and validated them by the finite element method.

关键词： High-voltage stator-cable windings Superconducting machines Inverted trapezoidal field winding Total harmonic distortion

Lead-free(Ba,Sr)TiO_(3)-based ceramics with superior tunable properties by the semi-solution method

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Journal of Advanced Ceramics 2024年第6期13卷 746-756页

作者： Yi Zhao Wenfeng Liu Dongsheng Ran Yihang Jin Zhiyuan Li Chengzhi Zhong Fanyi Kong Shengtao Li state Key Laboratory of electrical Insulation and power Equipment Xi’an Jiaotong UniversityXi’an 710049China Jiaxing electric power Company state grid zhejiang electric power Co. Ltd.Jiaxing 314000China

High-performance dielectric tunable materials with both high dielectric tunability and low dielectric loss are urgently needed for new-generation electronic tunable *** the present study,a new system,(Ba_(0.675)Sr_(0.325))_(1−x)La_(x)Ti_(1−x)MnxO_(3)(x=0.25%,0.5%,0.75%,and 1.0%),was *** acceptor dopant Mn was added to lower dielectric loss,while the donor dopant La was introduced to enhance dielectric *** samples were prepared using the conventional solid-state(CS)reaction method and the semi-solution(SS)*** experimental results showed that the morphology of the ceramics was optimized by further improving the processing *** microstructures,homogeneous grains,and uniform dopant distributions could be achieved successfully by the semi-solution ***,a significant enhancement in the tunable properties was realized owing to the improved microstructure mentioned *** optimum tunable properties occurred in the samples prepared by the semi-solution method at x=0.75%,with a high dielectric tunability of 85.0%,a low dielectric loss of 0.0011,and an excellent figure of merit(FOM)of *** tunable properties of(Ba,Sr)TiO_(3)(BST)ceramics were even superior to those of lead-based materials,with an FOM of approximately *** the results suggested that the semi-solution method rendered BST ceramics more promising for applications in tunable devices.

关键词： microstructure tunable properties (Ba,Sr)TiO_(3)(BST)ceramics semi-solution(SS)method

Non-intrusive Load Monitoring Based on Graph Total Variation for Residential Appliances

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Journal of Modern power Systems and Clean Energy 2024年第3期12卷 947-957页

作者： Xiaoyang Ma Diwen Zheng Xiaoyong Deng Ying Wang Dawei Deng Wei Li the College of electrical Engineering Sichuan UniversityChengdu 610065China state grid Chongqing electric power Company Chongqing 400014China state grid Sichuan electric power Company Chengdu 610095China state grid Hubei electric power Company Limited Research Institute Wuhan 430077China

Non-intrusive load monitoring is a technique for monitoring the operating conditions of electrical appliances by collecting the aggregated electrical information at the household power *** several studies on the mining of unique load characteristics,few studies have extensively considered the high computational burden and sample *** on lowfrequency sampling data,a non-intrusive load monitoring algorithm utilizing the graph total variation(GTV)is proposed in this *** algorithm can effectively depict the load state without the need for prior ***,the combined Kmeans clustering algorithm and graph signals are used to build concise and accurate graph structures as load *** GTV representing the internal structure of the graph signal is introduced as the optimization model and solved using the augmented Lagrangian iterative *** introduction of the difference operator reduces the computing cost and addresses the inaccurate reconstruction of the graph *** low-frequency sampling data,the algorithm only requires a little prior data and no training,thereby reducing the computing *** conducted using the reference energy disaggregation dataset and almanac of minutely power dataset demonstrated the stable superiority of the algorithm and its low computational burden.

关键词： Non-intrusive load monitoring graph total variation augmented Lagrangian function smart grid

Defect Detection in c-Si Photovoltaic Modules via Transient Thermography and Deconvolution Optimization

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Chinese Journal of electrical Engineering 2024年第1期10卷 3-11页

作者： Zekai Shen Hanqi Dai Hongwei Mei Yanxin Tu Liming Wang state grid Hangzhou power Supply Company State Grid Zhejiang Electric Power Co.Ltd.Hangzhou 310000China Huairou power Supply Branch State Grid Beijing Electric Power Co.Ltd.Beijing 101400China Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China

Defects may occur in photovoltaic(PV)modules during production and long-term use,thereby threatening the safe operation of PV power *** thermography is a promising defect detection technology;however,its detection is limited by transverse thermal *** phenomenon is particularly noteworthy in the panel glasses of PV modules.A dynamic thermography testing method via transient thermography and Wiener filtering deconvolution optimization is *** on the time-varying characteristics of the point spread function,the selection rules of the first-order difference image for deconvolution are *** with a broken grid and artificial cracks were tested to validate the performance of the optimization *** with the feature images generated by traditional methods,the proposed method significantly improved the visual *** defect size detection can be realized by combining the deconvolution optimization method with adaptive threshold *** the same batch of PV products,the detection error could be controlled to within 10%.

关键词： Photovoltaic module transient thermography point spread function deconvolution optimization quantitative detection

Decentralized Primary Frequency Regulation for Hybrid Multi-terminal Direct Current power Systems Considering Multi-source Enhancement

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Journal of Modern power Systems and Clean Energy 2024年第3期12卷 958-970页

作者： Jialiang Wu Zhen Wang Ruixu Liu Yu Shan Chenxuan Wang the College of electrical Engineering Zhejiang UniversityHangzhou 310027China the Economic Research Institute of state grid zhejiang electric power Co. Ltd.Hangzhou 310016China

Hybrid multi-terminal direct current(MTDC)transmission technology has been a research focus,and primary frequency regulation(FR)improvement in the receiving-end system is one of the problems to be *** paper presents a decentralized primary FR scheme for hybrid MTDC power systems considering multi-source enhancement to help suppress frequency disturbance in the receiving-end *** the converters only need local frequency or DC voltage signal input to respond to system disturbance without communication or a control center,i.e.,a decentralized control *** proposed scheme can activate appropriate power sources to assist in FR in various system disturbance severities with fine-designed thresholds,ensuring sufficient utilization of each power *** better balance FR performance and FR resource participation,an evaluation index is proposed and the parameter optimization problem is further ***,the validity of the proposed scheme is verified by simulations in MATLAB/Simulink.

关键词： Decentralized control scheme primary frequency regulation(FR) rate of change of frequency(ROCOF) system frequency disturbance

Multi-Time Scale Operation and Simulation Strategy of the Park Based on Model Predictive Control

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Energy Engineering 2024年第3期121卷 747-767页

作者： Jun Zhao Chaoying Yang Ran Li Jinge Song grid Center State Grid Shanxi Electric Power Company Electric Power Science Research InstituteTaiyuan030000China

Due to the impact of source-load prediction power errors and uncertainties,the actual operation of the park will have a wide range of fluctuations compared with the expected state,resulting in its inability to achieve the expected *** paper constructs an operating simulation model of the park power grid operation considering demand response and proposes a multi-time scale operating simulation method that combines day-ahead optimization and model predictive control(MPC).In the day-ahead stage,an operating simulation plan that comprehensively considers the user’s side comfort and operating costs is proposed with a long-term time scale of 15 *** order to cope with power fluctuations of photovoltaic,wind turbine and conventional load,MPC is used to track and roll correct the day-ahead operating simulation plan in the intra-day stage to meet the actual operating operation status of the ***,the validity and economy of the operating simulation strategy are verified through the analysis of arithmetic examples.

关键词： Demand response model predictive control multiple time scales operating simulation

Efficiency-oriented vehicle relocation of shared autonomous electric fleet in station-based car-sharing system

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 681-699页

作者： Ning Wang Hangqi Tian Jiahui Guo Huahua Wu Jian Lyu School of Automotive Studies Tongji UniversityShanghai 201804China state grid zhejiang electric power Co. Ltd.Hangzhou 310007China state grid zhejiang electric Vehicle Service Co. Ltd.Hangzhou 310012China

Long waiting delays for users and significant imbalances in vehicle distribution are bothering traditional station-based one-way electric car-sharing system *** address the problems above,a“demand forecast-station status judgement-vehicle relocation”multistage dynamic relocation algorithm based on the automatic formation cruising technology was proposed in this *** stage one,a novel trip demand forecast model based on the long short-term memory network was established to predict users'car-pickup and car-return order volumes at each *** stage two,a dynamic threshold interval was determined by combining the forecast results with the actual vehicle distribution among stations to evaluate the status of each *** vehicle-surplus,vehicleinsufficient,vehicle-normal stations,and the number of surplus or insufficient vehicles for each station were *** stage three,setting driving mileage and carbon emission as the optimization objectives,an integer linear programming mathematical model was constructed and the optimal vehicle relocation scheme was obtained by the commercial solver *** 43 stations and 187 vehicles in Jiading District,Shanghai,China,as a case study,results showed that rapid vehicle rebalancing among stations with minimum carbon emissions could be realized within 15 min and the users’car-pickup and car-return demands could be fully satisfied without any refusal.

关键词： Sustainable transportation One-way car-sharing Shared autonomous electric fleet Multistage dynamic relocation algorithm