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5th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2014

作者： Cheng, Lin Manjun, L.I.U. Peng, Feijin Dept. of Elec. Eng. Tsinghua University State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Beijing100084 China Guangdong Power Grid Company Foshan Power Supply Bureau Foshan528010 China

ISBN: (纸本)9789881532329

This paper describes several methods for condition-based maintenance, introduced CBM, RCM development process, the main theoretical logic, techniques and practices. Focuses on the health index based on equipment maintenance strategies, namely CBRM. Focused on the development of narrative context, theoretical foundation, model healthy index. And for its application in power transformers were introduced.

关键词： Condition based maintenance

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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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Direct heuristic dynamic programming method for power system stability enhancement

Direct heuristic dynamic programming method for power system...

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2014 American control Conference, ACC 2014

作者： Yu, Miao Lu, Chao Liu, Yongjun School of Mechanical-electronic and Automobile Engineering Beijing University of Civil Engineering and Architecture Beijing 100044 China State Key Laboratory for Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China Technology Research Centre of China Southern Power Grid Guangzhou 510623 China

ISBN: (纸本)9781479932726

In this paper a neural network-based approximate dynamic programming method, namely direct heuristic dynamic programming (direct HDP), is applied to power system stability control. Direct HDP is a learning and approximation based approach to address nonlinear system control under uncertainty. In the present paper, real-time system responses provided by wide area measurement system (WAMS) are used to construct such controllers which are uniquely tailored for the problems under consideration. In addition, the controller learning objective is formulated as a reward function that reflects global characteristics of the power system low frequency oscillation under the consideration of coupling effect among system components. The contribution of the paper includes a convergence proof of the direct HDP algorithm using an LQR framework, as well as case study to illustrate the proposed learning control algorithm. The case study aims at providing a new solution to a difficult large scale system coordination problem where the China Southern power Grid is used for. © 2014 American Automatic control Council.

关键词： controllers

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Design of grounding system for wind-photovoltaic-energy storage Hybrid power station 4

Design of grounding system for wind-photovoltaic-energy stor...

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2014 4th International Conference on High Voltage Engineering and Application, ICHVE 2014

作者： Lin, Cheng Sen, Wang Zhizhong, Li Jing, Wang Bo, Zhang Weidong, Shi Power Grid Grounding Engineering Laboratory of State Grid Corporation of China Xi'an Shaanxi710049 China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China China Electric Power Research Institute Beijing100192 China

ISBN: (纸本)9781479966134

Based on the Chinese demonstration project of Zhangbei wind-photovoltaic-energy storage (W-PV-ES) hybrid generation, which is the world's biggest and Chinese first new energy utilization platform, the design of grounding system for W-PV-ES Hybrid power station was studied in this paper. Firstly according to the soil resistivity of that power station, measured by the Wenner four-electrode method, the soil constitution, that is three-level layer in summer and is four-level layer including an 1.5m high and 2000·m permafrost in winter, was got, and grounding grid models of W-PV-ES hybrid generation was studied. Then grounding system of that W-PV-ES station was designed, that was the single wind turbine uses concentric bicyclic earth electrode, whose radius are 7m and 10m, and the PV-ES power station uses one horizontal earth electrode every 10m in one direction, every 50m in another direction, and there are 2.5m long vertical grounding rods every 10m around the PV-ES station. For the substation, we adopt the horizontal grounding grid with a 10m interval between conductors and 0.8m burial depth. On the condition that earth current is 10KA, the earth's surface potential, contact potential, and step potential were simulated. After that safety of 35kV system and secondary system were analyzed, when there was short trouble. Finally influence on earth resistance by different grounding materials was studied, galvanized flat steel and copper material was presented as two kinds of selection schemes of grounding materials for considering economic considerations. © 2014 IEEE.

关键词： Energy storage

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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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Air-gap magnetic field distribution and inductance characteristics in a long primary sectional powered variable pole pitch linear induction motor

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Qinghua Daxue Xuebao/Journal of Tsinghua University 2014年第9期54卷 1161-1165and1172页

作者： Mu, Shujun Chai, Jianyun Sun, Xudong Wang, Shanming State Key Lab. of Security Control and Simulation of Power Systems and Large Scale Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China

This study investigated the air-gap magnetic field distribution and inductance characteristics of a long primary sectional powered variable pole pitch linear induction motor (VPPLIM). A one-dimensional analytical model and a 2-D finite element model were used to analyze the air-gap magnetic field distribution in the VPPLIM with harmonic fields for uniformly accelerating the mover with a typical AC supply. The air-gap magnetic field distribution was used to develop analytical expressions for the self-and mutual-inductances of the motor and their characteristics. The analytical expressions are verified by the finite element simulations. ©, 2014, Press of Tsinghua University. All right reserved.

关键词： Inductance

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Optimization of tool-path generation for material extrusion-based additive manufacturing technology

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Additive Manufacturing 2014年 1卷 32-47页

作者： Jin, Yu-an He, Yong Fu, Jian-zhong Gan, Wen-feng Lin, Zhi-wei The State Key Lab of Fluid Power Transmission and Control Systems Department of Mechanical Engineering Zhejiang University Hangzhou310027 China Zhejiang Province's Key Laboratory of 3D Printing Process and Equipment Department of Mechanical Engineering Zhejiang University Hangzhou310027 China

In this study, we propose a tool-path generation approach for material extrusion-based additive manufacturing (AM) that considers the machining efficiency and fabrication precision, which are inherent drawbacks of general AM techniques compared with conventional manufacturing methods. The proposed approach aims to tackle the generation of direction-parallel tool-paths for the interior filling of simple connected areas, which comprises three main steps: (1) determining the inclination of reference lines;(2) generating and grouping tool-path segments into individual sub-paths;and (3) linking sub-paths based on specific requirements. These three modules interact to affect the efficiency and precision of AM significantly. In order to find an optimal inclination, we first analyze the impacts on the fabrication efficiency and manufacturing accuracy with different inclinations. A comparatively accurate building time model is developed subsequently to obtain the optimal tool-path inclination, but without compromising the machining precision, based on the analysis of a geometrical accuracy model. The proposed approach employs different inclinations in distinct layers according to specific manufacturing scenarios and technological requirements. After determining the reference lines, the tool-path segments are selected and grouped based on some characteristics (e.g., the number of intersections between reference lines and boundaries) to make up individual sub-paths, which are then connected to a zigzag-shaped path with short line segment connections. In the module for sub-path linking, some strategies are introduced to decrease the number of useless tool-paths, i.e., uncut paths, which could jeopardize the manufacturing quality by frequently turning the print head on and off. In addition, parametric curves are used to link the final sub-paths to avoid deceleration/acceleration processes in the end/starting parts of the sub-paths. The proposed approach has been used in practice

关键词： 3D printers

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Substation-control center two-level distributed network modeling

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第9期38卷 107-113and151页

作者： Wang, Jing Sun, Hongbin Chen, Runze Zhang, Yang Wu, Wenchuan Guo, Qinglai Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China National Electric Power Dispatching and Control Center Beijing100031 China

As the traditional centralized network modeling for energy management system (EMS) in control center is error prone, heavily reliant on maintenance, and lacking in self-healing ability while unable to satisfy the needs of the distributed application of future transmission grid, a method of substation-control center two-level distributed network modeling is presented. The information model including the network model as well as one-line diagram is built in the substation, transferred to the control center after transformation, and then merged to form an entire network model in control center. The architecture and key technologies such as substation modeling, model transferring and transforming, model joining are discussed in detail. The proposed method has been successfully implemented in China Eastern Grid as shown in the field-application results. ©2014 state Grid Electric power Research Institute Press.

关键词： Energy management systems

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Research on HVIGBT transient mixture model and parameter extraction method

Research on HVIGBT transient mixture model and parameter ext...

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

作者： Gaohui Feng Zhengming Zhao Liqiang Yuan Shiqi Ji Jincheng Zhao Mechanical Engineering College Shijiazhuang China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

This paper presents a kind of HVIGBT transient mixture model and corresponding parameter extraction method. The HVIGBT model can divide into MOSFET and BJT two parts. The two models are formed respectively according to HVIGBT work principle, in addition, the carrier transport equations have been simplified for avoiding Kirk effect in BJT model. The transient model is realized in PSIM software in the paper. Extraction methods, which include estimation by empirical values, calculation by testing waveforms and comparison with same type models, are adopted in extracting model parameters. Through comparing testing and simulation waveforms, the model's simulation accuracy is proved.

关键词： Mathematical model Testing Semiconductor device modeling Transient analysis Insulated gate bipolar transistors Integrated circuit modeling Capacitance

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Applications of coordinated automatic voltage control integrated for regional, provincial and prefectural control centers in China Southern power Grid

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第13期38卷 208-215页

作者： Wang, Bin Guo, Qinglai Zhou, Huafeng Tang, Lei Gu, Huijie Sun, Hongbin Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China China Southern Power Grid Dispatching Control Center Guangzhou510623 China

In order to avoid irrational reactive power flow and voltage distribution, the coordinated voltage controlsystem integrated for regional, provincial and prefectural control centers in China Southern power Grid is proposed. The reactive power and voltage operation and control characteristics of China Southern power Grid are analyzed. The hierarchical architecture of coordinated voltage controlsystem integrated for regional, provincial and prefectural control centers is described. Some typical applications are emphasized, including the coordination between regional and provincial control centers, the coordination between provincial and prefectural control centers, the voltage control for substations considering the provincial coordinate constraints, the coordinated voltage control for the high voltage direct current (HVDC) neighboring grids, etc, the exchange data content and mode between regional, provincial and prefectural control centers are described. The coordinated voltage control system is currently in real time operation in China Southern power Grid. © 2014 state Grid Electric power Research Institute Press

关键词： Reactive power

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