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3rd IEEE International Conference on Energy Internet, ICEI 2019

作者： Yang, Shandong Wang, Hongtao Yang, Dong Ma, Huan Zhao, Kang Key Laboratory of Power System Intelligent Dispatch Control Ministry of Education Shandong University Jinan China Shandong Electric Power Research Institute State Grid Jinan China

ISBN: (纸本)9781728114934

During the recovery of multi-infeed DC system after blackout, utilizing DC transmission to support the load recovery of receiving AC system can largely speed up the recovery process, but it will increase the challenges of voltage collapse at the same time because of the impactful reactive power consumption of DC. In order to avoid voltage collapse and give the power margin for recovery, this paper proposed the static voltage stability domain method to study the static voltage stability of DC participating in recovery. First, the impact of DC power is taken into account by adding DC power as variable parameters to the continuous power flow algorithm. Second, voltage collapse points are calculated using the improved continuous power flow algorithm to shape the static voltage stability domain. Then, the AC/DC power margin is defined as the shortest distance between operating point of system and the boundary of static voltage stability domain. Finally, the AC/DC power margin is calculated by using the normal of the boundary of static voltage stability domain to amend the power growth direction. The proposed AC/DC power margin can not only evaluate the voltage stability margin of multi-infeed DC system, but also guide the power recovery control. The effectiveness of this proposed method is validated in the test system. © 2019 IEEE.

关键词： Recovery

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A convex hull based intertemporal loadability set approximation method

A convex hull based intertemporal loadability set approximat...

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2020 Tsinghua - HUST-IET Electrical Engineering Academic Forum

作者： Xinfei Yan Haiwang Zhong Zhenfei Tan Junfeng Yang Dept. Electrical Engineering Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China Power Dispatch & Control Center State Grid Corp. of China Beijing China

ISBN: (纸本)9781839533914

The uncertainty of renewable energy sources has aroused the interests in depicting the ability of power systems to accommodate the variations. Loadability set is one of the typical methods to characterize the feasible sets of power systems with uncertainties. The existing literature on loadability set do not incorporate intertemporal constraints, while for some cases like security check, intertemporal constraints are necessary and important. This paper firstly adapts loadability set to security check, enabling it to depict the capability of power systems to accommodate load variations. Singular value decomposition (SVD) and progressive vertex enumeration (PVE) are introduced to lighten the computational burden caused by multiple periods. The computational time can be traded off with the precision of approximation to the loadability set. Case studies verify that the loadability set can be approximated with proper precision.

关键词： Loadability feasible set convex hull security check loading capacity safety check convex hull power systems Approximation method

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LCL Resonance Analysis and Damping in Single-Loop Grid-Forming Wind Turbines

arXiv

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arXiv 2025年

作者： Chen, Meng Xi, Yufei Blaabjerg, Frede Cheng, Lin Lestas, Ioannis Department of Engineering University of Cambridge CambridgeCB2 1PZ United Kingdom State Key Laboratory of Power System Operation and Control Tsinghua University Beijing100084 China AAU Energy Aalborg University Aalborg9220 Denmark

A dynamic phenomenon known as LCL resonance is often neglected when stability analysis is carried out for grid-forming (GFM) control schemes by wind turbine systems, due to its high frequency. This paper shows that this simplification is not always valid for single-loop (SL) control schemes. A detailed small-signal analysis reveals that reactive power (RAP) control significantly influences the resonant modes, which may be dominant in determining overall system stability, even if the resonant frequency is high. The underlying mechanism via which the LCL resonance may dominate the overall system stability is systematically analyzed. Furthermore, various RAP control strategies are compared to assess their different effects on resonant modes. An active damping (AD) strategy favorable for SL-GFM control is then designed. We also provide a comparison between SL-GFM and well-studied grid-following control schemes, highlighting quite different resonance features between them. Finally, case studies associated with a 14-bus, 5-machine IEEE test system are presented. These show that instability originates from the LCL resonance rather than low-frequency interactions among multiple machines, validating the theoretical analysis and the proposed AD strategy. © 2025, CC BY-NC-ND.

关键词： Wind turbines

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Excellent electrical properties of zinc-oxide varistors by tailoring sintering process for optimizing line-arrester configuration

Excellent electrical properties of zinc-oxide varistors by t...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Pengfei Meng Wei Cao Chao Chen Shuai Wan Heng Xu Jun Hu Jinliang He Tsinghua University Beijing China Wuhan NARI Limited Liability Company State Grid Electric Power Research Institute Wuhan China Guangdong Aikang Electric Power Co. Ltd Guangzhou China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

We optimized the excellent electrical performance of zinc-oxide (ZnO) varistors doping of aluminum and indium by tailoring the sintering process. The surface morphology, nonlinear volt ampere properties, capacitance-voltage characteristics, and dielectric analyses were carried out. At a given aluminum and indium concentration, the average sample grain size ( d) increased as lengthening sintering time from 0.5 to 2.5 h. The voltage gradient ( E1mA) decreased from 602.4 V/mm to 356.7 V/mm. The residual voltage of the sintered varistors at the lightning impulse current ( 8/20 μs) decreased as the samples sintering holding time extended from 0.5 to 2.0 h. When the ZnO varistor was sintered for 1.5 h, the samples showed an excellent performance, with a reference voltage of 479.3 V/mm at 1 mA DC. When assembled in the line surge arresters, the obtained high-voltage-gradient ZnO varistors can decrease their length and residual voltage, which allows for better coordination of the line surge arrester with the insulators. This study has great significance to optimize line-arrester configurations and improve power-system stability.

关键词： Zinc oxide Varistors Arresters II-VI semiconductor materials Surges Insulators Dielectrics

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Cathode Pressure control of Air Supply system for PEMFC⋆ ⁎

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IFAC-PapersOnLine 2021年第10期54卷 247-252页

作者： Huayang Liu Hai Yin Tianwei Ding Xiaoliang Huang Jinwu Gao State Key Laboratory of Automotive Simulation and Control Jilin University Changchun 130022 China Department of Control Science and Engineering Jilin University Campus Nanling Changchun 130022 China Research and Development Institute China FAW Group Company Changchun 130013 China Chalmers University of Technology Department of Electrical Engineering Division of Electric Power Engineering SE–412 96 Göteborg Sweden

This paper proposes a backstepping method controller for the polymer electrolyte membrane fuel cell (PEMFC)air supply system. The control objective is adjusting the cathode pressure to its reference value quickly, in order to solve the problem of excessive extreme pressure difference between anode and cathode in practice. Considering model uncertainty and some disturbances, we design an extend state observer (ESO) to estimate disturbances. Next, a backstepping method is proposed to adjust control law. Finally, the experiment results demonstrate the effectiveness and robustness of the control strategy.

关键词： PEMFC Air supply system Cathode pressure tracking control ESO Backstepping method

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Optimal operation of microgrids with risk-constrained state of charge

Optimal operation of microgrids with risk-constrained state ...

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European control Conference (ECC)

作者： Jie Lei Christian A. Hans Pantelis Sopasakis State Key Laboratory of Power Transmission Equipment & System Security and New Technology at Chongqing University China Control Systems Group at Technische Universität Berlin Germany School of EEECS and the i-AMS Centre at Queen’s University Belfast UK

In this paper we present a stochastic scenario-based model predictive control (MPC) approach for the operation of islanded microgrids with high share of renewable energy sources. We require that the stored energy remains within given bounds with a certain probability using risk-based constraints as convex approximations of chance constraints. We show that risk constraints can generally be cast as conic constraints and, unlike chance constraints, can control both the number and average magnitude of constraint violations. Lastly, we demonstrate the risk-constrained stochastic MPC in a numerical case study.

关键词： Renewable energy sources Costs Stochastic processes Europe Microgrids state of charge Frequency control

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power Output Monitoring and Anomaly Identification of Photovoltaic systems Using Graphical Modeling

Power Output Monitoring and Anomaly Identification of Photov...

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International Conference on Sensing, Diagnostics, Prognostics, and control (SDPC)

作者： Yonghua Chen Xiaochen Zhang Gang Liu Rui Wu Chao Liu Dongxiang Jiang NARI Technology Co. Ltd. NARI Group Corporation (State Grid Electric Power Research Institute) Nanjing China Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728170503

ISBN: (纸本)9781728170510

Photovoltaic cells are being increasingly installed worldwide as a type of important renewable resource for power generation. Among the installed photovoltaic systems, data are collected from the control and monitoring system, and the anomaly detection researches are mostly based on the individual photovoltaic cells and the systematic behavior in a group of photovoltaic systems is not well studied. Based on the assumption that the photovoltaic cells installed in the same location are with very close solar radiation, the power output of each subsystem is considered in this work for monitoring the operating status of the subsystem and identifying the anomalous subsystem, where spatiotemporal pattern network, a probabilistic graphical modeling approach, is applied. The results show that the presented framework is able to detect the anomaly and locate the anomalous subsystem.

关键词： Photovoltaic systems Fault diagnosis Photovoltaic cells Data models Spatiotemporal phenomena Monitoring Anomaly detection

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Real-time object detection method based on improved YOLOv4-tiny

arXiv

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arXiv 2020年

作者： Jiang, Zicong Zhao, Liquan Li, Shuaiyang Jia, Yanfei Key Laboratory of Modern Power System Simulation and Control and Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin132012 China College of Electrical and Information Engineering Beihua University Jilin132013 China

The "You only look once v4" (YOLOv4) is one type of object detection methods in deep learning. YOLOv4-tiny is proposed based on YOLOv4 to simple the network structure and reduce parameters, which makes it be suitable for developing on the mobile and embedded devices. To improve the real-time of object detection, a fast object detection method is proposed based on YOLOv4-tiny. It firstly uses two ResBlock-D modules in ResNet-D network instead of two CSPBlock modules in Yolov4-tiny, which reduces the computation complexity. Secondly, it designs an auxiliary residual network block to extract more feature information of object to reduce detection error. In the design of auxiliary network, two consecutive 3x3 convolutions are used to obtain 5x5 receptive fields to extract global features, and channel attention and spatial attention are also used to extract more effective information. In the end, it merges the auxiliary network and backbone network to construct the whole network structure of improved YOLOv4-tiny. simulation results show that the proposed method has faster object detection than YOLOv4-tiny and YOLOv3-tiny, and almost the same mean value of average precision as the YOLOv4-tiny. It is more suitable for real-time object detection, especially for developing on embedded devices. Copyright © 2020, The Authors. All rights reserved.

关键词： Object detection

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Dynamic Economic Dispatch Considering Transmission-Distribution Coordination and Automatic Regulation effect of Transmission system

Dynamic Economic Dispatch Considering Transmission-Distribut...

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IEEE/IAS Industrial and Commercial power system Asia (I&CPS Asia)

作者： Yuqian Wu Mingqiang Wang Mengxia Wang Linguo Jing Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University Jinan China State Grid Tangshan Power Supply Company Tangshan China State Grid Binzhou Power Supply Company Binzhou China

ISBN: (数字)9781728143033

ISBN: (纸本)9781728143040

With the increase of proportion of renewable energy, the uncertainty in power system is significantly increased, and the security operation of power system is facing more challenges. In traditional economic dispatch model, the unit output and load are expressed by constant power, which ignores the automatic regulation effect during system operation. And the transmission system and distribution system are separated optimized, the coordination effect is not considered. In this paper, a new dynamic economic dispatch model is proposed and the automatic regulation effect and transmission-distribution coordination are considered, which can improve the renewable energy accommodation and enhance the system operation security and economics. The validity and effectiveness of the proposed model are illustrated by case studies.

关键词： Voltage control Load modeling Economics power system dynamics Renewable energy sources Reactive power

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Initiation and propagation behaviors of small fatigue crack in titanium alloy TC4

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key Engineering Materials 2019年 795卷 9-14页

作者： Zhu, Lei Hu, Xu Teng Jiang, Rong Song, Ying Dong Qu, Shou Dao Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing210016 China Herbert Gleiter Institute of Nanoscience Nanjing University of Science and Technology Nanjing210094 China

The initiation and propagation behaviors of small fatigue crack in TC4 were investigated in the present work. Surface replication on the basis of a two-part silicon mixture and confocal laser scanning microscope were used to record and observe the small crack initiation and growth processes at room temperature in air. Results showed that surface cracks initiated from the interfaces between α and β phases. When the crack lengths were below ~200 μm, the crack growth rates exhibited large oscillations and temporary retardations due to the presence of α/β interfaces. The corner crack propagated much faster and might have shielding effect on the surface crack. © 2019 Trans Tech Publications Ltd, Switzerland.

关键词： Crack initiation

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