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11th Asia-Pacific International Conference on Lightning, APL 2019

作者： Meng, Pengfei Wan, Shuai He, Jinliang Zhao, Xiaolei Xu, Heng Yang, Xiao Hu, Jun State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Wuhan NARI Limited Liability Company State Grid Electric Power Research Institute Wuhan China

ISBN: (纸本)9781728116952

In this work, we studied multiple dopants based ZnO varistors and optimizing its microstructure and electrical properties by tailoring the sintering characteristics. The properties were evaluated by scanning electron microscopy (SEM), current-voltage characteristics, capacitance-voltage characteristics, dielectric characteristics and X-ray diffraction characteristics. At a given gallium and indium concentration, the residual voltage ratio of the sintered varistors under the 5/20μs impulse current decreased obviously as the sintering temperature increased from 1100°C to 1250°C. Besides, the nonlinear coefficient was first increased and then decreased with increasing sintering temperature. The multiple doped ZnO varistors sintered at 1250°C showed optimal performance, exhibiting a grain size of 7.1μm, residual voltage ratio of 1.56, voltage gradient of 416 V/mm, leakage current of 0.79 μA/cm2, and nonlinear coefficient of 73. When applied in power systems, the high voltage gradient varistors will make the line surge arrester in better coordination with insulators as well as reach the goal of low cost and miniaturization of GIS tank-type arresters. © 2019 IEEE.

关键词： Varistors

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Polymeric insulating materials characteristics for high-voltage applications

Nature Reviews Electrical Engineering

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Nature Reviews Electrical Engineering 2024年 516-528页

作者： Tian-Yu Wang Gui-Xin Zhang Zhi-Min Dang Jie Mao Boya Zhang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Department of Chemical and Biomolecular Engineering University of California Los Angeles CA USA School of Chemistry and Chemical Engineering State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering Ningxia University Yinchuan China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong University Xi’an China

Large-scale power system transmission and transformation equipment operates in high-voltage environments, placing notable requirements on the insulation strength of polymers used in core insulation frameworks. Increasing the polymer insulation performance in high-voltage environments is crucial for protecting large-capacity and integrated power equipment and ensuring the safe and stable operation of electrical devices. Here, we discuss the phenomena and the underlying mechanisms of bulk breakdown and surface flashover that lead to insulation failure in polymers and present relative strategies to increasing the performance of the insulating materials. We analyse the challenges faced by polymeric insulating materials in various extreme environments and the strategies to address them. Finally, we identify key challenges and highlight future directions and opportunities for the development of reliable polymeric insulating materials.

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Evaluating Comprehensive Development Quality of a Regional power Grid by Using an Integrated Multi-criteria Decision-Making Methodology 6

Evaluating Comprehensive Development Quality of a Regional P...

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2019 6th International Conference on Advanced Composite Materials and Manufacturing Engineering, ACMME 2019

作者： Zhang, Xiaodong Qin, Kaiming Si, Ruihua Ge, Xianjun State Grid Henan Electric Power Company Zhengzhou450018 China State Key Laboratory of Power System and Power Generation Equipment Control and Simulation Department of Electrical Engineering Tsinghua University HaidianBeijing100084 China

Due to the economic situation changes and the continuous expansion of new energy power in China, a new evaluation methodology based on multi-criteria decision making (MCDM) should be proposed to promote the comprehensive development of the new regional power grid. Some criteria were selected to constitute an indicator system from the perspectives of the safety reliability, network structure and economic benefit. Then, an integrated evaluation model was proposed based on fuzzy AHP method and VIKOR method was applied to calculate a series of comprehensive evaluation indexes. A regional power grid was chosen as an empirical analysis to demonstrate the feasibility of the evaluation system. © Published under licence by IOP Publishing Ltd.

关键词： Decision making

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Analysis and suppression of subsynchronous oscillation of Rudong wind power through MMC-HVDC system

Analysis and suppression of subsynchronous oscillation of Ru...

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2021 Annual Meeting of CSEE Study Committee of HVDC and power Electronics (HVDC 2021)

作者： J. Li X. Xie J. Yang H. Li Z. Shi K. Wang C. Fu W. Yang Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province Huadong Engineering Corporation Limited Power China Hangzhou Zhejiang Province 310014 China State Key lab of Control and Simulation of Power Systems and Generation Equipment (Dept. of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 China

There may be complex interaction between the converter control systems of wind power and MMC-HVDC, which will lead to sub-/super-synchronous oscillation and threaten the safe and stable operation of the system. The relevant events have been reported in Guangdong Nan'ao, Shanghai Nanhui and Zhangbei projects. Rudong offshore wind power project is the first offshore wind power transmission system in China, and it is still under construction. Therefore, it is of great significance to carry out the research on the risk analysis and suppression measures of sub-synchronous oscillation in Rudong wind power MMC-HVDC system. First, the time-domain simulation model of Rudong wind power MMC-HVDC system is built in the PSCAD/EMTDC simulation model. Then, the effects of the number of wind turbine generators, wind power output and the parameters of MMC-HVDC controller on the sub-/super-synchronous oscillation characteristics of the system are further analyzed. Finally, the suppression measures based on supplementary frequency dependent gain control are proposed, the application position of the controller is discussed, and the parameter optimization method of the controller is given. The research content provides a certain guiding significance for the operation and control of Rudong wind power MMC-HVDC.

关键词： turbogenerators HVDC power transmission wind turbines power transmission control risk analysis time-domain analysis offshore installations HVDC power convertors wind power plants wind power

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Fault diagnosis for PV arrays considering dust impact based on transformed graphical features of characteristic curves and convolutional neural network with CBAM modules

引用

Applied Energy 2024年 355卷

作者： Jiaqi Qu Qiang Sun Zheng Qian Lu Wei Hamidreza Zareipour School of Instrumentation and Optoelectronic Engineering Beihang University Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China School of Electronics and Information Engineering Beihang University Beijing China The Department of Electrical and Computer Engineering University of Calgary Calgary Canada

Various faults can occur during the operation of photovoltaic (PV) arrays, and both dust-affected operating conditions and various diode configurations complicate the faults. However, current methods for fault diagnosis based on I-V characteristic curves usually do not effectively use all the distinguishable information contained in the I-V curves or often rely on calibrating the field characteristic curves to standard test conditions (STC). It is difficult to apply these methods in practice and accurately identify multiple complex faults with similarities in different blocking diode configurations of PV arrays under the influence of dust. Therefore, a novel fault-diagnosis method for PV arrays that considers the impact of dust is proposed. In the pre-processing stage, the Isc-Voc normalized Gramian angular difference field (GADF) method is presented, which normalizes and transforms the resampled PV array characteristic curves from the field, including I-V and P-V, to obtain transformed graphical feature matrices. Subsequently, in the fault diagnosis stage, the convolutional neural network (CNN) model with convolutional block attention modules (CBAM) is designed to classify faults, which identifies complex fault types from the transformed graphical matrices containing complete discriminative fault information. In addition, the performances of different graphical feature transformation and CNN-based classification methods are compared using case studies. The results indicate that the developed method for PV arrays with different blocking diode configurations under various operating conditions has high fault diagnosis accuracy and reliability.

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Space Charge Characteristics of Oil-paper under AC/DC Composite Voltage

Space Charge Characteristics of Oil-paper under AC/DC Compos...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yuanxiang Zhou Xin Huang Ling Zhang Yunxiao Zhang Zhongliu Zhou Chenyuan Teng Lei Xue Meng Huang The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Haidian Beijing China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power Universiy Beijing China

ISBN: (纸本)9781728195728;9781728195735

Oil-paper insulation bears AC/DC composite voltage in converter transformers. However, the AC/DC space charge behavior is still not clear, which will result in electric field distortion, material aging and even insulation failure. In this work, the space charge distribution of oil-paper under the AC/DC composite voltage with the AC/DC ratio of 1:1, 1:3, 1:5, and 1:7, is studied by pulse electroacoustic (PEA) method, respectively. It was found that as DC component increases, the accumulated charge near the electrode decreases, while the interior charge increases. It suggests that DC stress mainly influences the amount and the depth of space charge accumulation. AC component has a relatively significant impact on the injection and extraction behavior of space charge near the electrode. Furthermore, AC/DC composite voltage enhances the migration of space charge compared with that under DC voltage. This research contributes to the further understanding of the space charge characteristics of oil-paper under AC/DC composite voltage, which will benefit the safe and stable operation of converter transformers.

关键词： Electrodes Conferences Space charge Oil insulation Aging Distortion Dielectrics

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Ultrathin microcrystalline hydrogenated Si/Ge alloyed tandem solar cells towards full solar spectrum conversion

引用

Frontiers of Chemical Science and Engineering 2020年第6期14卷 997-1005页

作者： Yu Cao Xinyun Zhu Xingyu Tong Jing Zhou Jian Ni Jianjun Zhang Jinbo Pang Key Laboratory of Modem Power System Simulation and Control&Renewable Energy Technology Northeast Electric Power UniversityJilin 132012China School of Electrical Engineering Northeast Electric Power UniversityJilin 132012China School of Chemical Engineering Northeast Electric Power UniversityJilin 132012China Key Laboratory of Photo-electronics Thin Film Devices and Technique of Tianjin Institute of Photo-electronic Thin Film Devices and TechnologyCollege of Electronic Information and Optical EngineeringNankai UniversityTianjin 300350China Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong Institute for Advanced Interdisciplinary Research(iAIR)University of JinanJinan 250022China

Thin film solar cells have been proved the next generation photovoltaic devices due to their low cost,less material consumption and easy mass *** them,micro-crystalline Si and Ge based thin film solar cells have advantages of high efficiency and ultrathin absorber *** individual junction devices are limited in photoelectric conversion efficiency because of the restricted solar spectrum range for its specific *** this work,w e designed a nd simulated a multi-junction solar cell with its four sub-cells selectively absorbing the full solar spectrum including the ultraviolet,green,red as well as near infrared range,respectively.B y tuning the G e content,the record efficiency of 24.80%has been realized with the typical quadruple junction structure of a-Si:H/a-Si0.9Ge0.1:H/μc-Si:H/μc-Si0.5Ge0.5:*** further reduce the material cost,thickness dependent device performances have been *** can be found that the design of total thickness of 4μm is the optimal device design in balancing the thickness a nd the *** the design of ultrathin quadruple junction device with total thickness of 2μm is the optimized device design regarding cost and long-term stability with a little bit more reduction in *** results indicated that our solar cells combine the advantages of low cost and high *** work may provide a general guidance rule of utilizing the full solar spectrum for developing high efficiency and ultrathin multi-junction solar cells.

关键词： thin films solar cells quadruple junction solar cell amorphous silicon silicon germanium alloy quantum efficiency

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Contaction of Atoms for Outstanding Dielectric Characteristics in Kx-Passivated Polymer Dielectrics

SSRN

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SSRN 2022年

作者： Li, Xiao-Fen Wang, Tian-Yu Liu, Bai-Xin Liu, Jian-Bo Zhang, Gui-Xin Wang, Zhong Lin School of Materials Science and Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China CAS Center for Excellence in Nanoscience Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing100083 China School of Nanoscience and Technology University of Chinese Academy of Sciences Beijing100049 China School of Material Science and Engineering Georgia Institute of Technology AtlantaGA30332 United States

High dielectric characteristics polymer dielectrics are crucial for high-power, high-integration, and high-energy storage density electrical devices and film capacitors. However, polymer dielectrics accumulate much charge during operation, causing local electric field distortion and flashover or breakdown. The deep-level defect state (electron/hole accumulation center) is a fundamental factor affecting dielectric strength. Unfortunately, related research, especially on passivating deep-level defects in polymer dielectrics, is minimal. In this paper, based on experiments and first-principles calculations, it is found that KX (X=F, Cl, Br, I) effectively passivates deep-level defect states in polymer dielectrics. Further analysis of the physical passivation mechanism reveals that the deep-level defect cation passivation principle is the cation dipole effect on polymers. The principle of anion passivation of deep-level defects by suspending anions and cations is the key to producing more stable C covalent bonds. This stable covalent bond transfers the local charge from the C with the lone electron pair that originally contains the hanging bond. Therefore, some transfer occurs and the anion implements effective passivation. This paper addresses the design of high-performance polymer dielectrics, providing a reference for experimental and theoretical analyses. © 2022, The Authors. All rights reserved.

关键词： Passivation

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Potential Evaluation of Distributed Energy Resources with Affine Arithmetic

Potential Evaluation of Distributed Energy Resources with Af...

引用

2019 IEEE PES Innovative Smart Grid Technologies Asia, ISGT 2019

作者： Cheng, Lin Qi, Ning Guo, Yanfei Liu, Nan Wei, Wei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China State Grid Beijing Daxing Power Supply company Beijing China

ISBN: (纸本)9781728135205

With the rapid development of Energy Internet, the penetration of distributed energy resources is gradually increasing. New methods for potential evaluation of DERs is becoming more and more important for planning, operation, and control. In this paper, the traditional affine arithmetic-based forward-backward power flow calculation method is introduced. Then, modified method is proposed mainly considers arithmetic correction, weekly looped structure, and different types of DG. Moreover, comprehensive potential evaluation structure for DERs is proposed based on affine arithmetic which involves three parts. Finally, through numerical analysis, the applicability and error of the affine arithmetic method are analyzed. © 2019 IEEE.

关键词： Internet of Energy

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Optimizing the Homogeneity and Efficiency of A Solid Oxide Electrolysis Cell Based on Multiphysics simulation and Data-Driven Surrogate Model

SSRN

引用

SSRN 2022年

作者： Chi, Yingtian Yokoo, Kentaro Nakajima, Hironori Ito, Kohei Lin, Jin Song, Yonghua State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100087 China Department of Hydrogen Energy Systems Graduate School of Engineering Kyushu University Fukuoka Japan Department of Mechanical Engineering Faculty of Engineering Kyushu University Fukuoka Japan Tsinghua-Sichuan Energy Internet Research Institute Chengdu610213 China State Key Laboratory of Internet of Things for Smart City University of Macau 999078 China

Inhomogeneous current and temperature distributions are harmful to the durability of the solid oxide electrolysis cell (SOEC). Segmented SOEC experiments reveal that a high steam utilization, which is favorable for system efficiency, leads to local steam starvation and enhanced the inhomogeneity. It is necessary to consider inhomogeneity and efficiency jointly in optimization studies. Three-dimensional (3D) multiphysics models can simulate the inhomogeneity in a reliable manner, but they are unsuitable for optimization due to the high computational cost. This study proposes a method that combines segmented SOEC experiments, multiphysics simulation, and artificial intelligence to optimize the inhomogeneity and efficiency of SOEC. A 3D cell model is first built and verified by segmented SOEC experiments. Then, fast neural network surrogate models are built from the simulation data and integrated into a multi-objective optimization problem. Its solutions form a Pareto front reflecting the conflicting relationships among different objectives. It is found that the down-stream current is 60%-65% of the up-stream current when the steam utilization is 0.7. To increase the steam utilization to 0.8, the down-stream current further drops to 50%-60% of the up-stream current. The Pareto fronts enable system operators to achieve a balance between efficiency and inhomogeneity. © 2022, The Authors. All rights reserved.

关键词： Multiobjective optimization

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