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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Yi Lin Zhang-sui Lin Liu-qing Qiu Ming-ye Zhang Department of Power Network Research Center State Grid Fujian Power Economic Research Institute Fuzhou China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781509054190

This paper presents an optimal power flow model for AC/DC meshed networks with modular multi-level converter based HVDC transmission system (MMC-OPF). The MMC-OPF problem is formulated to minimize the total network loss of the whole AC/DC grids by adjusting generators and converters. In addition, a practical method is proposed to consider N-1 static security constraints with OPF calculation. Case studies of IEEE testing system and a practical network have been carried out. The results demonstrate the effectiveness of the method.

关键词： Indexes Switches

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Linear Precoding Design for MIMO-PLC systems

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Tsinghua Science and Technology 2015年第2期20卷 155-163页

作者： Jisheng Peng the State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua Uinversity

In this paper, we consider the design of linear precoding in Multiple Input Multiple Output （MIMO） power Line Communication （PLC） systems with finite-alphabet input. First, we derive mutual information of MIMO-PLC systems with impulsive noise. Considering the non-concavity of the objective function and the low-cost requirement of PLC systems, we choose the lower bound of the mutual information as the objective function. Subsequently, we propose a novel approach to design the precoding scheme to reduce computational complexity. Specifically, our work primarily includes the following two contributions：（1） We design the right unitary matrix that is a product of two fixed unitary matrices, which only depends on the modulation mode. Hence, the results can be saved and require less computations. （2） For the power allocation matrix, we first reduce the space of power allocation using constraints of the optimal power allocation policy. Consequently, we propose a non-linear search method to obtain the optimal power allocation in small space. In regards to the computational complexity of the analysis, we conclude that the proposed precoding matrix design scheme has low complexity and is easy to implement. Moreover, the numerical results are proven to demonstrate the performance of the proposed precoding design scheme.

关键词： precoding design MIMO-PLC impulsive noise finite-alphabet input

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Electrical tree initiation and propagation in silicone rubber under long-term AC aging

Electrical tree initiation and propagation in silicone rubbe...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yunxiao Zhang Yuanxiang Zhou Ling Zhang Ming Chen Xu Zhang Yanchao Sha State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing Beijing CN State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China North China Electric Power Research Institute Co Ltd Beijing Beijing CN North China Electric Power Research Institute Co Ltd. Beijing China

Electrical tree break-down is the major failure problem in cable accessories, however, mechanisms of the electrical tree initiation and propagation are still lack of deeply research, especially in silicone rubber (SIR) which is widely used as insulation material for cable accessories. Long-term aging (0- 1000 h) experiments under the different voltages were conducted to observe electrical tree initiation and propagation processes. In trees initiation stage, with increasing of applied voltage, electrical tree initiation probability becomes larger, while tree initiation time dramatically decreases. The experiment observations demonstrated four shapes of trees which are dominated. As applied voltage increasing, the numbers of electrical trees life-cycles increased and exponential relationship was found between tree length and magnitude of applied voltage. It is noted that charges, whose energy exceeding a certain critical value, destroy microstructure of dielectric accumulatively via injection and extraction, and cause electrical trees initiate when it accumulates to a visible extent.

关键词： Electrodes Aging power cables Electric fields Needles power cable insulation

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Unit Commitment Considering Demand Response Behavior Based on Utility Maximization

Unit Commitment Considering Demand Response Behavior Based o...

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IEEE Conference on Energy Internet and Energy System Integration

作者： Yumin Zhang Xueshan Han Bo Xu Li Zhang Donglei Sun Xiaofeng Miao Jiayin Jiang Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment (Department of Electrical Engineering Tsinghua University) Economic & Technology Research Institute of State Grid Shandong Electric Power Company State Grid Shandong Electric Power Company Yantai Electric Power Company

ISBN: (纸本)9781538614280

The active participation of demand side resources in power grid operation not only benefits the individual participant but also benefits the whole system. The optimal goal can promote by excavating the active behaviors of demand side. The welfare maximization of market participant is the driving force of such active behaviors. Considering the independence of each user's behavior, the consumer's utility function is selected to depict consumer's preference and demand response behavior. In order to coordinate the consumers' maximum welfare with social welfare maximization, consumers' utility function and units' operation cost are integrated into Unit Commitment (UC) model. The objective function is to maximize social welfare, by subtracting units' operation cost from consumers' total utility, and this objective can be acquired. Considering the proposed model should be solved in a distributed manner, the idea of the centralized coordination and the decentralized decision-making is proposed. Based on the Lagrangian relaxation (LR) principle and distributed real-time pricing scheme, a closed-loop feedback mechanism is constructed to reflect the relationship among generator output, price level, and load demand. The ten generating units example can illustrate the effectiveness of the proposed method.

关键词： Demand utility Decomposition coordination Electricity market Lagrangian relaxation Real-time pricing Unit commitment

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High impedance fault detection on distribution systems with harmonic interference in wind farms

High impedance fault detection on distribution systems with ...

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13th International Conference on Development in power System Protection 2016 (DPSP)

作者： Jiang Ni Bin Wang Xinzhou Dong State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

High impedance faults (HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. To solve this problem, the typical HIF arc flash based on Mayr's arc model is first built, and the typical fault waveforms of HIF in wind farm are presented. Then the characteristics of high impedance faults are analysed to distinguish the occurrence of HIF from other harmonic interference. After that, the performance of the traditional harmonic based HIF detection algorithm is discussed, and a novel detection algorithm is presented to prevent harmonic interference influence in wind farms.

关键词： distribution system Wind farm high impedance faults harmonic algorithm

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Repeated Strike Process During Disconnector Operation in Ultra-High Voltage Gas-Insulated Switchgear

Repeated Strike Process During Disconnector Operation in Ult...

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作者： Guan, Yonggang Cai, Yuanji Chen, Weijiang Liu, Weidong Li, Zhibing Yue, Gongchang Zhang, Junmin State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China State Grid Corporation of China Beijing100031 China China Electric Power Research Institute Beijing100192 China School of Automation Science and Electrical Engineering Beihang University Beijing100191 China

Very fast transient over-voltage (VFTO), induced by disconnector operations in gas-insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investigate single-strike waveforms of VFTO. However, little study has been carried out investigating the repeated strike process, which would influence VFTO significantly. In this paper, we carried out 450 effective experiments in an ultra-high voltage test circuit, and conducted calculations through the Monte Carlo simulation method, to investigate the repeated strike process. Firstly, the mechanism of the repeated strike process is proposed, based on the experimental results. Afterwards, statistical breakdown characteristics of disconnectors are obtained and analyzed. Finally, simulations of the repeated strike process are conducted, which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO. This study enhances the understanding of the nature of VFTO, and may help to optimize the disconnector designed to minimize VFTO.

关键词： Monte Carlo methods

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Author Correction: Near-real-time monitoring of global CO2 emissions reveals the effects of the COVID-19 pandemic

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Nature communications 2020年第1期11卷 6292页

作者： Zhu Liu Philippe Ciais Zhu Deng Ruixue Lei Steven J Davis Sha Feng Bo Zheng Duo Cui Xinyu Dou Biqing Zhu Rui Guo Piyu Ke Taochun Sun Chenxi Lu Pan He Yuan Wang Xu Yue Yilong Wang Yadong Lei Hao Zhou Zhaonan Cai Yuhui Wu Runtao Guo Tingxuan Han Jinjun Xue Olivier Boucher Eulalie Boucher Frédéric Chevallier Katsumasa Tanaka Yiming Wei Haiwang Zhong Chongqing Kang Ning Zhang Bin Chen Fengming Xi Miaomiao Liu François-Marie Bréon Yonglong Lu Qiang Zhang Dabo Guan Peng Gong Daniel M Kammen Kebin He Hans Joachim Schellnhuber Department of Earth System Science Tsinghua University Beijing China. zhuliu@***. Laboratoire des Sciences du Climat et de l'Environnement LSCE CEA CNRS UVSQ Centre d'Etudes Orme de Merisiers Gif-sur-Yvette France. Department of Earth System Science Tsinghua University Beijing China. Department of Meteorology and Atmospheric Science The Pennsylvania State University University Park PA USA. Department of Earth System Science University of California Irvine 3232Croul Hall Irvine CA USA. Division of Geological and Planetary Sciences California Institute of Technology Pasadena CA USA. Jet Propulsion Laboratory California Institute of Technology Pasadena CA USA. Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment Technology School of Environmental Science and Engineering Nanjing University of Information Science and Technology Nanjing China. Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China. Climate Change Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China. Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China. School of Environment Tsinghua University Beijing China. School of Mathematical School Tsinghua University Beijing China. Department of Mathematical Sciences Tsinghua University Beijing China. Center of Hubei Cooperative Innovation for Emissions Trading System Wuhan China. Faculty of Management and Economics Kunming University of Science and Technology 13 Kunming China. Economic Research Centre of Nagoya University Furo-cho Chikusa-ku Nagoya Japan. Institut Pierre-Simon Laplace Sorbonne Université/CNRS Paris France. Université Paris Dauphine Place du Maréchal de Lattre de Tassigny 75016 Paris France.

A Correction to this paper has been published: https://***/10.1038/s41467-020-20254-5.

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A dynamic multi-level temporal and spatial coordination method for orderly power utilization based on customer load curtailment cost characteristics

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Dianwang Jishu/power System Technology 2016年第2期40卷 425-432页

作者： Yan, Qingguo Tong, Xing Zhang, Ning Chen, Xiao Yi, Yongxian State Grid Jiangsu Electric Power Company NanjingJiangsu Province210024 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Jiangsu Electric Power Company Research Institute NanjingJiangsu Province210019 China State Grid Key Laboratory of Electric Power Metrology NanjingJiangsu Province211103 China

When there is power supply shortage or emergency event in power system, orderly power utilization needs to be applied to cut down electricity demand to maintain power supply for important electricity consumers. Current orderly power utilization fails to consider curtailment costs for different regions and customers, and ignores temporal continuity and production regularity of customer, leading to inefficient load curtailment scheduling. This paper proposes a dynamic multi-level temporal and spatial coordinated shortage allocation method considering customer load curtailment costs for orderly power utilization. Load curtailment cost function is established from individual customer level up to provincial electrical grid level. An optimization model is proposed to strategically rearrange customer load profiles across multiple periods. Case studies show that the method efficiently coordinates power shortage in temporal and spatial scale, and significantly brings down economic cost due to curtailment allocation. This model could help promote customer satisfaction level in orderly power utilization. © 2016, power System Technology Press. All right reserved.

关键词： Electric power utilization

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Design of an additive manufactured XY compliant manipulator with spatial redundant constraints 35

Design of an additive manufactured XY compliant manipulator ...

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第35届中国控制会议

作者： ZHANG Zhen LIU Binbin WANG Peng YAN Peng State Key Laboratory of Tribology & Institute of Manufacturing Engineering Department of Mechanical EngineeringTsinghua University Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua University State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University School of Automation Science and Electrical Engineering Beihang University School of Mechanical Engineering Shandong University

ISBN: (纸本)9781509009107

This paper presents an additive manufactured beam flexure-based XY positioning stage with spatial redundant *** order to restrict rotational error motions of the guidance module,a spatial redundant constraint is *** additive manufacturing technique is adopted to monolithically fabricate the proposed positioning *** simulation results show that the proposed XY positioning stage is capable to achieve ±2 x 2 mm2 working *** fabricated prototyping stage shows that the advanced manufactured flexure mechanism can achieve good geometric effect and could be a good alternative to a metal-based flexure mechanism.

关键词： Nanopositioning Beam flexure mechanism Additive manufacturing

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The Application Of Variational Mode Decomposition For Diagnosing Rub-Impact Fault Of Dual-Rotor System Based On Acceleration Measurements

The Application Of Variational Mode Decomposition For Diagno...

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The 29th International Congress on Condition Monitoring and Diagnostic Engineering Management

作者： Nanfei Wang Dongxiang Jiang Te Han Yizhou Yang Hongzhi Xu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal EngineeringTsinghua University

ISBN: (纸本)9781510868434

As for aero-engine,it is relatively difficult to obtain the displacement signal,only to measure the acceleration *** the paper,aimed at the dual-rotor system test rig,the rub-impact is simulated and the acceleration signals collected from the bearing pedestal are analysed to extract the rubbing faults' ***-component extraction is an available method for vibration signal analysis of rotary machinery,so a novel method of rubbing fault diagnosis based on variational mode decomposition(VMD) is *** is a newly developed technique for adaptive signal decomposition,which can non-recursive decompose a multi-component signal into a number of quasi-orthogonal intrinsic mode *** the rub-impact fault occurs in the dual-rotor system,the acceleration vibration signals of the dual-rotor system will present amplitude-modulated feature because of the periodic rub-impact between the rotor and the *** is then applied to detect multiple rubbing-caused signatures for rotor-stator fault diagnosis via practical vibration *** using VMD,the rub-impact signal,background signal and noise signal can be separated efficiently and the fault feature of vibration signal of a rotor system with local rub-impact fault can be ***,the VMD method can be applied to the rub-impact fault diagnosis of the rotor systems efficiently.

关键词： Dual-rotor variational mode decomposition rubbing demodulation impact

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