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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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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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Travelling wave based single phase grounding protection for distribution system

Travelling wave based single phase grounding protection for ...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Dong, Xinzhou Wang, Jun Shi, Shenxing Wang, Bin Dominik, Bak Kirby, Brian Yang, Xia State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Alstom Grid Stafford ST174LX United Kingdom

ISBN: (纸本)9781849198349

It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.

关键词： Wavelet transforms

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Coupled planning of water resources and agricultural land-use based on an inexact-stochastic programming model

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Frontiers of Earth Science 2014年第1期8卷 70-80页

作者： Cong DONG Guohe HUANG Qian TAN Yanpeng CAI MOE Key Laboratory of Regional Energy and Environmental Systems Optimization Resources and Environmental Research Academy North China Electric Power University Beijing 102206 China State Key Laboratory of Water Environment Simulation School of Environment Beijing Normal University Beijing 100875 China Institute for Energy Environment and Sustainable Communities University of Regina Saskatchewan S4S 7H9 Canada

Water resources are fundamental for support of regional development. Effective planning can facilitate sustainable management of water resources to balance socioeconomic development and water conservation. In this research, coupled planning of water resources and agricultural land use was undertaken through the develop- ment of an inexact-stochastic programming approach. Such an inexact modeling approach was the integration of interval linear programming and chance-constraint pro- gramming methods. It was employed to successfully tackle uncertainty in the form of interval numbers and probabil- istic distributions existing in water resource systems. Then it was applied to a typical regional water resource system for demonstrating its applicability and validity through generating efficient system solutions. Based on the process of modeling formulation and result analysis, the developed model could be used for helping identify optimal water resource utilization patterns and the corresponding agri- cultural land-use schemes in more, a number of decision three sub-regions. Further- alternatives were generated under multiple water-supply conditions, which could help decision makers identify desired management policies.

关键词： water resources management regional water system planning scenario analysis uncertainty

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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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Failure analysis of fan mill in thermal power plant 68

Failure analysis of fan mill in thermal power plant

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68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

作者： Liu, Chao Jiang, Dongxiang Chu, Fulei Department of Mechanical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

Fan mill is an important device in thermal plants, which supply coal power to boiler. Crack failures recently occurred in pulverizing wheels of fan mills in a power plant in China. The cracks happens in quite a few pulverizing wheels and they affect the normal operation. To find out the root cause of the cracks, Finite Element Analysis (FEA) of the pulverizing wheel is carried out in this work. The assembly with real dimensions is modelled to calculate the concentrated stress and strain with centrifugal load, driving load, and operational temperature taken into account. Contact effects are included in the finite element model as well as nonlinear material property. Based on the analysis, the crack causes are determined: (i) the initial stress exceeds the yield limit in normal operational condition, resulting low safety coefficient;(ii) the stress increases significantly in the worn pulverizing wheel, where the risk of failure is greatly increased.

关键词： Cracks

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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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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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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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Impact of inertia control of DFIG wind turbines on system small-signal stability

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第23期38卷 6-12页

作者： Chen, Runze Wu, Wenchuan Sun, Hongbin Lan, Haibo Liu, Haitao Liu, Xiaomin 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 State Grid Jibei Electric Power Company Limited Beijing100053 China

The impact of inertia control of doubly-fed induction generator (DFIG) wind turbines on the small-signal stability of systems is studied. Firstly, the principle of DFIG wind turbines offering inertia responses is discussed, followed by the introduction of two approaches of inertia control. Then, possible influences of two control schemes on system small-signal stability are analyzed. Finally, on the basis of simulation, the modal analysis method is adopted to analyze the influence characteristics of different control strategies and various control parameters on system small-signal stability. Analysis results show that inertia control may have an appreciable impact on the system small-signal stability. Therefore, security constraints of small-signal stability should be carefully considered when designing the control strategy and parameters. ©, 2014 state Grid Electric power Research Institute Press.

关键词： Wind turbines

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