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23rd International Congress on Condition Monitoring and Diagnostic engineering Management, COMADEM 2010

作者： Jiang, Dongxiang Liu, Chao An, Xueli Chen, Jie State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9784883254194

The cracks emerged in a fossil-fired power plant in China in 2008 and several similar crack accidents had been detected in nuclear turbines in USA before. The possible causes of the cracks are analyzed in previous study while the torsional vibration is one of the most significant factors. The paper analyzes the impact of torsional vibration using the practical running data in some turbine generator unit. Based on the transient response analysis under emulational subsynchronous oscillation model simplified from the practical network, the torques acted on the coupling section are analyzed. Then the stress and strain field is calculated for local dangerous point search in Zone of Vulnerability (ZoV) and the fatigue damage criterion determination. Manson-Coffin equation is used to ascertain whether it is high-cycle fatigue or low-cycle fatigue and the fatigue data from standard test specimen is used. The method using local stress and strain analysis as well as fatigue damage cumulation study may establish a novel way to diagnose the crack in an early stage.

关键词： Transient analysis

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Experimental investigation and analysis for gearbox fault

Experimental investigation and analysis for gearbox fault

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2010 2nd World Non-Grid-Connected Wind Power and Energy Conference, WNWEC 2010

作者： Li, Shaohua Jiang, Dongxiang Zhao, Minghao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781424489213

As an important component of a wind turbine drive chain, the high failure rate of the gearbox can have a serious impact on the operation of wind turbine units. The fault diagnosis of the gearbox is therefore important for the safety of wind turbine units. In this paper, a gearbox experiment rig was built, experiments on the gear surface spalling fault were held on the rig under laboratory conditions, the shaft vibration displacement signals were collected, related vibration signals were analyzed by time domain, amplitude domain, frequency domain and wavelet analysis, and the results of different analysis methods were compared. The results show that the waveform of normal and fault signals are similar, the amplitude of the signals will change while the fault happens, and the wavelet analysis is more effective than frequency domain analysis on gearbox fault features extraction. © 2010 IEEE.

关键词： Frequency domain analysis

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Application of back propagation neural network to fault diagnosis of direct-drive wind turbine

Application of back propagation neural network to fault diag...

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2010 2nd World Non-Grid-Connected Wind Power and Energy Conference, WNWEC 2010

作者： An, Xueli Jiang, Dongxiang Li, Shaohua State Key Laboratory of Control and Simulation of Power System and Generation Equipments Dept. of Thermal Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781424489213

The vibration signals of wind turbines are highly nonlinear and non-stationary due to wind turbine operation conditions that are very complicated. The signals will be more complex when a fault occurs. Aiming at these problems, a fault diagnosis method for direct-drive wind turbine is presented based on back propagation neural network (BPNN). The time-domain feature parameters of vibration signals in the horizontal and vertical direction are considered in the method. Five experiments of direct-drive wind turbine with normal, wind wheel mass imbalance, wind wheel aerodynamic imbalance, yaw and blade break are carried out in laboratory scale. Through analyzing the features of five conditions, the time-domain feature parameters in horizontal and vertical direction of the vibration signal are selected as the input samples of BPNN. By training, the BPNN model can be constructed between feature parameters and fault types. The validity of the BPNN model is verified using test samples. The results indicate that the proposed method has higher diagnostic accuracy. It can used in on-line fault diagnosis of direct-drive wind turbines. © 2010 IEEE.

关键词： Failure analysis

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Discussion on setting calculation of loss-of-excitation protection for large turbogenerator

Discussion on setting calculation of loss-of-excitation prot...

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作者： Yao, Siwang Wang, Weijian Luo, Ling Gui, Lin Qiu, Arui State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9788986510119

Loss of excitation (LOE) is a common fault found in the generators. The most widely applied method for detecting a generator loss of excitation is the use of impedance relays to sense the variation of impedance as viewed from the generator terminals [1]. However, compared with China's approachs, in the setting of impedance circle, the IEEE's allow the circle to extend along the negative X axis, meanwhile, in the latest edition of the "IEEE Guide for AC Generator Protection", the circle is further extended, reaching to -*** think this is adverse, to prove our point, the paper ,basing on the IEEE 9 bus model and using computer digital simulation, have studied various loss-of-excitation conditions and some system disturbances that may lead to the relay false tripping. simulation results indicate that the IEEE's method not only can't accelerate the operation effectively, but also will increase the chances of maloperation.

关键词： Electric equipment protection

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Capacity credit evaluation of wind power with sequential Monte Carlo method

Capacity credit evaluation of wind power with sequential Mon...

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2010 International Conference on E-Product E-Service and E-Entertainment, ICEEE2010

作者： Kong, Xiangyu Cui, Kai Jia, Hongjie Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China State Power Economic Research Institute Beijing China

ISBN: (纸本)9781424471614

Wind can be considered as an interesting alternative to fossil fuels, but as a power source, is both intermittent and diffuse. It is necessary to calculate wind equivalent capacities in order to introduce a coherent evaluation of wind production in the management of the centralized production park. Base on the sequential Monte Carlo simulation technique for wind speeds, an auto-regressive and moving average time series model was used to simulate wind power. And a capacity credit evaluation of wind power method was proposed, which provides the existence probability of wind generation possible outage capacity levels. A number of sensitivity analyses were presented with case studies to illustrate possible applications of the proposed method. ©2010 IEEE.

关键词： Wind power

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Effect of NiCr clad BaF2·CaF2 addition on wear performance of plasma sprayed chromium carbide-nichrome coating

Effect of NiCr clad BaF2·CaF2 addition on wear performance ...

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作者： Du, Lingzhong Huang, Chuanbing Zhang, Weigang Zhang, Jingmin Liu, Wei State Key Laboratory of Multi-Phase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100080 China China Iron and Steel Research Institute Group Beijing 100081 China

NiCr clad BaF2·CaF2 fluoride eutectic powders were added into chromium carbide-nichrome feedstock to improve the tribological properties of NiCr-Cr3C2 coating, and the structures, mechanical, and ball-on-disk sliding wear performance of the coating were characterized. The results show that NiCr cladding can effectively decrease the density and thermophysical difference between the feedstock components, while alleviate the decarburization and oxidization of the constituent phases, and form the coating with a uniform and dense microstructure. However, the addition of BaF2·CaF2 has a negative effect on mechanical properties of the coating. When the temperature reaches 500 °C, the BaF 2·CaF2 eutectic is soften by the heat and smeared by the counterpart, thus the low shear stress lubricating film forms between the contact surface, that improves the tribological properties dramatically. At this temperature, the dominant wear mechanisms also change from splats spallation and abrasive wear at room temperature to plastic deformation and plawing by the counterpart. Within the temperature range from 600 to 800 °C, the friction coefficient, the wear rates of NiCr/Cr3C 2-10% BaF2·CaF2 coating and its coupled Si3N4 ball are 20%, 40%, and 75% lower than those of the NiCr/Cr3C2 coating, respectively. The NiCr/Cr 3C2-BaF2·CaF2 coating shows superior wear performance to the NiCr/Cr3C2 coating without lubricant additive. © ASM International.

关键词： Friction

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Analysis on the negative sequence impedance directional protection for stator internal fault of turbo generator

Analysis on the negative sequence impedance directional prot...

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作者： Hao, Liangliang Sun, Yuguang Arui, Qiu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9788986510119

In order to protect more turn-to-turn faults for the turbo-generator with only three lead-out terminals in the neutral side, this paper applies a new principle protection - negative sequence impedance directional protection of fault components for stator internal asymmetrical fault. By means of Multi-loop Method, all possible internal short-circuit faults and single branch shutdown faults of a 300MW turbo-generator are calculated to obtain the protection performance. Calculation and performance analysis show that, this new principle protection is superior to other existing protections in the aspect of sensitivity and protection range, especially for interturn faults of turbogenerator stator winding. In addition, it won't incorrectly trip on external faults. Thus, this new principle protection can provide safeguard of high quality for internal faults in turbo-generator with only three lead-out terminals in the neutral side.

关键词： Stators

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Design and implementation of the high efficiency photovoltaic system with solid state lighting

Design and implementation of the high efficiency photovoltai...

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作者： Hu, Xianlai Yuan, Liqiang Chen, Jian Zhao, Zhengming State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9788986510119

Photovoltaic application of LED lighting has been a hot trend in residential illumination, for it integrates the advantages of both the PV systems and LED lights. However, it has a series of problems, such as high thermal loss, poor reliability, and a short life span. To address these problems, this paper presents a deep research on the whole system from a low-cost, high-efficiency and long-life point of view. A main circuit integrating maximum power point tracing (MPPT) control and battery management, as well as a double-loop control for LED load is developed. A set of protection system is applied to ensure high reliability of the system. The control strategies are tested on the demonstrator and prove to be effective.

关键词： Integrating circuits

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Finite element method for a nonsmooth elliptic equation

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中国高等学校学术文摘·数学 2010年第2期5卷 191-209页

作者： Lili CHANG Wei GONG Ningning YAN State Key Laboratory of Scientific and Engineering Computing Institute of Systems Science Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100190 China

In this paper, we study the finite element method for a nonsmooth elliptic equation. Error analysis is presented, including a priori and a posteriori error estimates as well as superconvergence analysis. We also propose two algorithms for solving the underlying equation. Numerical experiments are employed to confirm our error estimations and the efficiency of our algorithms.

关键词： Finite element method nonsmooth elliptic equation a priori error estimate a posteriori error estimate superconvergence analysis active set method

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Research on Multi-agent Based C4ISR Effectiveness simulation and Evaluation

Research on Multi-agent Based C4ISR Effectiveness Simulation...

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International Conference on Computer Modeling and simulation, ICCMS

作者： Zhang Ying-chao Ye Feng Yu Qin-zhang Chen Xin National Key Laboratory of Science and Technology on Complex Systems Simulation Beijing Institute of System Engineering Beijing China

The effectiveness evaluation of C4ISR is playing a more and more important role in its designing, developing and using. According to its characters, such as complexity and intelligence, the traditional evaluation methods and systems are not feasible and effective enough. In this paper, a multi-agent based simulation and evaluation framework of C4ISR is advanced, which includes the architecture and the working procedure. The agent-based simulation model of C4ISR is put forward, according to which the C2 Agent, Armament Agent and the Evaluation Agent are founded. The interaction model between each agent is also designed. At final, based on the Swarm, a multi-agent based C4ISR effectiveness simulation and evaluation prototype is developed, through which NATO C2 effectiveness evaluation is thoroughly analyzed.

关键词： Analytical models Computational modeling Computer simulation Adaptive systems Intelligent agent Design engineering systems engineering and theory Laboratories Virtual prototyping Information technology

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