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Probabilistic substation fault diagnosis considering instrumentation channels and heterogeneous information: A unified Bayesian network model

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Qinghua Daxue Xuebao/Journal of Tsinghua University 2014年第10期54卷 1384-1390页

作者： Mu, Jianan Sun, Hongbin Wu, Wenchuan Guo, Qinglai Zhang, Boming State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China

Fault diagnosis plays an important role in improving power network troubleshooting capability. Conducting local fault diagnosis in substations can make full and quick use of abundant local information. A substation fault diagnosis method was presented based on Bayesian network to adapt to a wealth of information and distributed autonomy under smart grid environment. The method is effective in dealing with uncertainties induced by malfunctions of protection relays and circuit breakers as well as instrumentation channel errors. Heterogeneous information available in substations, such as sequence of events (SOEs), wave records and blocking signals, was also integrated into the method, with the junction tree algorithm used to conduct probabilistic reasoning. The results show that breaker SOEs can be better utilized when considering instrumentation channels. Furthermore, introduction of wave records and blocking signals can significantly improve diagnosis accuracies. ©, 2014, Press of Tsinghua University. All right reserved.

关键词： Bayesian networks

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Reducing the Impact of Source Internal Resistance by Source Coil in Resonant Wireless power Transfer

Reducing the Impact of Source Internal Resistance by Source ...

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IEEE Energy Conversion Congress and Exposition

作者： Yiming Zhang Ting Lu Zhengming Zhao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781479957774

Wireless power transfer (WPT) is the state-of-the-art research interest. In the WPT system efficiency is an important figure of merit. In order to reduce the impact of the source internal resistance and improve the system efficiency of the conventional two-coil structure, a source coil is added to the two-coil structure, forming a three-coil structure. Both the two-coil structure and the three-coil structure are modeled and analyzed with the circuit theory. The system efficiencies of both structures with optimal loads and a fixed load are deduced. The system efficiency of the three-coil structure is proved to be higher than that of the two-coil structure. An experimental apparatus is implemented and the experimental results match well with the theoretical calculations. The larger the source internal resistance, the more significantly the addition of the source coil improves the system efficiency.

关键词： Coils Wireless communication Resistance Magnetic resonance Integrated circuit modeling Equivalent circuits

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Sustained overvoltage control considering power system restoration dynamic process

Sustained overvoltage control considering power system resto...

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2014 International Conference on Energy Research and power Engineering, ERPE 2014

作者： Chen, Bin Wang, Hong Tao Wei, Zhong Kang Wang, Chun Yi Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University Jinan 250061 China State Grid Jibei Electric Power Company Beijing 100053 China State Grid Shandong Electric Power Company Jinan 250001 China

ISBN: (纸本)9783038351603

Changeable sensitivity and safety margin are proposed in this paper, which can avoid the voltage violation according to the operation of the current situation. A simulation test is presented to demonstrate the proposed method can decrease adjusting amounts and restoration time efficiently. © (2014) Trans Tech Publications, Switzerland.

关键词： Restoration

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Coordinated control of variable-speed constant-frequency wind farms in weak grids

Coordinated control of variable-speed constant-frequency win...

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2014 International Conference on Energy Research and power Engineering, ERPE 2014

作者： Li, Chao Wang, Hong Tao Wei, Zhong Kang Wang, Chun Yi Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University Jinan 250061 China State Grid Jibei Electric Power Company Beijing 100053 China State Grid Shandong Electric Power Company Jinan 250001 China

ISBN: (纸本)9783038351603

Variable-speed constant-frequency (VSCF) wind farms are gradually becoming a significant proportion of generation in weak grids with constantly increasing penetration rate, and it should certainly take responsibility of the grid frequency and voltage stability. Based on the P-Q performance curve of doubly fed induction generator (DFIG), by introducing static synchronous compensator (STATCOM), this paper presents a coordinated control strategy of active power and reactive power to deal with fault and load disturbance in weak grids. simulation results show that the proposed coordinated control strategy can effectively improve the frequency and voltage stability of the grids. © (2014) Trans Tech Publications, Switzerland.

关键词： Wind farm

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A combined PWM algorithm to eliminate spikes of common mode voltages

A combined PWM algorithm to eliminate spikes of common mode ...

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IEEE Conference and Expo Transportation Electrification Asia-Pacific (ITEC Asia-Pacific)

作者： Fang Liu Zhengming Zhao Ting Lu Shusheng Wei Kai Li Sate Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Various pulse width modulation strategies have been proposed to reduce the common mode voltage (CMV) in the variable speed motor drive system. However, unexpected voltage spikes appear as a result of the dead time effect. This paper investigates the principles of those reduced CMV PWM (RCMV PWM) methods mathematically and analyzes the reasons for those voltage spikes theoretically and experimentally. Results suggest that three-dimension active zero state PWM and near state PWM can effectively eliminate the spikes even with the dead time effect taken into consideration. Then a combined algorithm using those two methods is proposed, and it covers the linearity modulation region as large as the conventional space vector PWM. The switchover between those two methods is smooth along with the variation of the modulation index. Experimental results show that no distortion is brought to the modulation wave and verify the validity and feasibility of the proposed combined algorithm.

关键词： Pulse width modulation Vectors Switches Inverters Integrated circuits Induction motors

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Dynamic fuzzy modelling for organic rankine cycle systems

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ICIC Express Letters 2014年第11期8卷 3007-3013页

作者： Zhang, Jianhua Wang, Zhuofei Li, Bo Wang, Rui Lin, Mingming State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University No. 2 Beinong Road Changping District Beijing China Shisanling Pumped Storage Power Station Changping District Beijing China School of Control and Computer Engineering North China Electric Power University No. 2 Beinong Road Changping District Beijing China

Based on recursive fuzzy c-means (FCM) algorithm, the Takagi-Sugeno model is established for Organic Rankine Cycle (ORC) based waste heat recovery systems. The premise parameters are obtained by FCM algorithm while the consequent parameters are identified by forgetting factor least-square (FFLS) algorithm. The validity of identification algorithm is tested and verified. simulation results show that the established T-S model can characterize the dynamic characteristics of the ORC system well.

关键词： Waste heat

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Erratum to: On secondary new particle formation in China

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Frontiers of Environmental Science & Engineering 2016年第5期10卷 10页

作者： Markku Kulmala Tuukka Petäjä Veli-Matti Kerminen Joni Kujansuu Taina Ruuskanen Aijun Ding Wei Nie Min Hu Zhibin Wang Zhijun Wu Lin Wang Douglas R. Worsnop University of Helsinki Helsinki Finland Joint International Research Laboratory of Atmospheric and Earth System Sciences (JirLATEST) Nanjing University and University of Helsinki Nanjing China Institute for Climate and Global Change Research Nanjing University Nanjing China State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing China Max Planck Institute for Chemistry Mainz Germany Department of Environmental Science & Engineering Fudan University Shanghai China Aerodyne Research Inc. Billerica USA

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RF energy harvesting with broadband antenna

RF energy harvesting with broadband antenna

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IEEE Conference and Expo Transportation Electrification Asia-Pacific (ITEC Asia-Pacific)

作者： Xudong Wang Zhengming Zhao Guanhua Chen Fanbo He State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing P. R. China

A broadband RF energy harvesting system over a frequency range of 900MHz-3GHz has been designed and tested. Some detailed issues of RF design have been studied and tested to improve the efficiency of the rectifier. Test results show that as low as -20dBm RF power can be harvested by this system. The series and parallel connections of two RF energy harvesting systems have also been studied, compared with the single system.

关键词： Radio frequency Broadband antennas Rectifiers Energy harvesting Broadband communication Antenna measurements

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Research on structural optimal design of a car plastic back door

Research on structural optimal design of a car plastic back ...

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2014 International Conference on Mechatronics and Intelligent Materials, MIM 2014

作者： Yu, Duo Nian Wu, Zhi Jia Zhao, You Qun Gu, Li Yang Liu, Jing Min State Key Laboratory of Automotive Simulation and Control Jilin University Changchun China College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics China FAW-Volkswagen Automotive Company Ltd Changchun China

ISBN: (纸本)9783038351412

This paper takes a passenger car back door as an example with the use of glass fiber reinforced PET to replace steel. The sampling space is sampled by the optimal Latin hypercube experimental method and according to the experimental data, it establishes the polynomial response surface (RSM) model. Select NSGA-Π genetic algorithm to optimize the back door assembly thickness of multi-objection with the purpose of lightweight. © (2014) Trans Tech Publications, Switzerland.

关键词： Multiobjective optimization

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What is the primary cause of the observed widespread increases in precipitation intensity

What is the primary cause of the observed widespread increas...

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2015中国科协海峡两岸青年科学家学术活动月两岸环保高层专家论坛

作者： Run Liu Shaw C.Liu Ralph J.Cicerone C.J.Shiu Jun Li Jingli Wang Yuanhang Zhang State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmenta Research Center for Environmental Changes Academia Sinica Taipei 11529 Department of Atmospheric S National Academy of Sciences Washington DC 20001 USA and also at Earth System Science University Research Center for Environmental Changes Academia Sinica Taipei 11529 Institute of Urban Meteorology of China Meteorological Administration Beijing 100089

Significant increases in precipitation intensity, as a result of increases of heavy precipitation and/or decreases of light precipitation have been observed over widespread regions of the *** wanning and effects of anthropogenic aerosols have been proposed as possible causes of these *** this work we identify the primary cause of the increases in precipitation intensity by contrasting observed characteristics of precipitation in the tropical 10°S-10°N oceanic region to those at higher latitudes (5°N-20°N, 20°N-45°N land area) in the Northern Hemisphere (NH) for 1979-2007, and a polluted region in eastern China (1955-2011).Significant increases in heavy precipitation and/or decreases in light precipitation with net increases in precipitation intensity are found in all regions examined, while amounts of total precipitation show relative small or negligible *** of these changes suggest that global warming rather than aerosol effects is the primary cause of the changes.

关键词： Extreme precipitation global warming aerosols risk of floods and droughts

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