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Prognostics and Health Management Solutions Conference - PHM: Driving Efficient Operations and Maintenance, MFPT 2012

作者： Chen, Jie Jiang, Dongxiang Yang, Wenguang Deng, Xiaowen Feng, Yongxin State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 China Electric Power Institute Guangdong Grid Company Guangzhou 510080 China

Distinguishing fault types in early time can prevent wind turbines from breaking down. C4.5 algorithm, different from ID3 algorithm, which can deal with continuous parameters, should be a choice fault diagnosis method of wind turbine. This paper strives to extract fault classification rules of wind turbine based on data collected from a small wind turbine in laboratory using C4.5 decision tree and validate the rules extracted using another set of data. According to the solution, fault types such as mass imbalance of rotor, aero-dynamic asymmetry, yaw misalignment, gearbox and bearing fault and so on can be distinguished by the method presented in this paper.

关键词： Wind turbines

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A new battery energy storage system control method based on SOC and variable filter time constant

A new battery energy storage system control method based on ...

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2012 IEEE PES Innovative Smart Grid Technologies, ISGT 2012

作者： Guo, Li Zhang, Ye Wang, Cheng Shan Key Laboratory of Smart Grid of Ministry of Education Tianjin University Tianjin 300072 China Key Laboratory of Power System Simulation and Control of Ministry of Education School of Electrical Engineering and Automation Tianjin University Tianjin 300072 China

ISBN: (纸本)9781457721588

Because of large fluctuations and strong randomness of active power generated by renewable energy resources, taking into account the constraints such as battery life cycle, a new battery energy storage system control method based on real-time state-of-charge and variable filter time constant is presented. This method could compensate the fluctuation composition of a particular frequency band of power. At the same time, filter time constant is adjusted in order to stabilize the value of SOC in a certain range, and over-charging and over-discharging of the battery is avoided. A photovoltaic (PV) and battery hybrid system modeled by PSCAD is tested to verify the validity of this method. © 2012 IEEE.

关键词： Hybrid systems

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Soft-switching analysis of a resonant capacitor current feedback self-oscillating inverter

Soft-switching analysis of a resonant capacitor current feed...

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2012 IEEE 7th International power Electronics and Motion control Conference - ECCE Asia, IPEMC 2012

作者： Shao, Mingsong Huang, Songling Zhao, Wei Wang, Changquan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Lighting Research Center Century Zhuoke Energy and Technology Co. LTD Beijing China

ISBN: (纸本)9781457720864

In this paper, we examine a resonant capacitor current feedback (RCCF) self-oscillating resonant inverter from nonlinear point of view. By adopting a four-stage equivalent model, we derive the soft-switching dead time from time-domain for the series resonant capacitor linked parallel load circuit. Importantly, we propose a nonlinear model for the current feedback and gate-drive circuit. Based on analyzing the switching transition interval of this model, the determination of feedback parameters is inferred with given input power and resonant elements. Experimental results have been obtained for a RCCF self-oscillating inverter operating at 3 MHz and 300 V bus voltage. © 2012 IEEE.

关键词： Feedback

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Investigation of bipolar block emergency in UHVDC convertor station caused by lightning stroke

Investigation of bipolar block emergency in UHVDC convertor ...

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2012 31st International Conference on Lightning Protection, ICLP 2012

作者： Zhang, Xiao Yu, Zhanqing He, Jinliang Luo, Bin Cai, Hansheng State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Xipeng Chen Technology Research Centre China Southern Power Grid Co. Ltd Guangzhou Guangdong Province China

ISBN: (纸本)9781467318976

It is noteworthy that bipolar block emergencies of the ±800kV UHVDC system in China happened twice within two years caused by lightning strokes. To recur and investigate the mechanism of such emergencies, lightning transient performance and relative electromagnetic interference (EMI) in the UHVDC system are investigated. Wide-band circuit models of major UHVDC equipments are set for calculation, while the lightning stroke shielding failure process and transmission corona loss are also considered during the simulation. By combining the fault records in the converter station and simulation results , possible ways of EMI into the secondary system produced by primary circuit lightning transient are analyzed. The results would help explain the cause of such bipolar block emergency and provide reference for protection methods of lightning caused EMI in UHVDC system. © 2012 IEEE.

关键词： Lightning

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Study on coordinated voltage control strategy of DFIG wind farm

Study on coordinated voltage control strategy of DFIG wind f...

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IEEE General Meeting power& Energy Society

作者： Hui-fen Chen Ying Qiao Zong-xiang Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781467327275

This paper studies a combined voltage control strategy that coordinates a variety of reactive compensative devices such as fixed capacitors, SVC/Statcom, DFIGs (Double-fed Induction Generators) to improve voltage control performance in multi-time scale. Based on the control restraints and response performance, three modes - planning mode, online mode and emergency mode - are optimized for lower cost and higher security margin, respectively. The paper introduces wind power forecast into wind farm voltage planning for slow, discrete devices such as fixed capacitor, while engages devices that are capable of instantaneous response to smooth quick, small voltage fluctuation and track online voltage reference from dispatching centre. The feasibility, effectiveness and superiority of the proposed control strategy are verified with simulation.

关键词： Wind farms Reactive power Automatic voltage control Security Capacitors Static VAr compensators

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The large-size low-stray-parameter planar bus bar for high power IGBT-based inverters

The large-size low-stray-parameter planar bus bar for high p...

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International Conference on Electrical Machines and systems (ICEMS)

作者： Liqiang Yuan Hualong Yu Xuesong Wang Zhengming Zhao Ting Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

The large-size planar DC bus bar is widely used in high power converters, whose stray parameters are significantly affected the converter reliability and performance. Taking the example of an actual 315kW/400V inverter, the design, simulation and analysis for its bus bar stray parameters is described in detailed. Being different from the conventional method that considers the bus bar conductor as an entirety, an improved method is proposed in this paper, which separates the bus bar into several segments and evaluates the influence of stray parameters in each segment to the power semiconductor devices respectively. Therefore, this improved method can provide support for the more accurate and effective design and optimization of bus bar. In addition, two different structure of bus bar are implemented in the actual inverter, the comparison and analysis of experiment results for both structures proves the validity of the proposed method.

关键词： Inverters Insulated gate bipolar transistors Equivalent circuits Integrated circuit modeling Inductance Conductors Snubbers

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A new method of frequency-dependent network equivalence for power system

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Science China(Technological Sciences) 2012年第7期55卷 1894-1907页

作者： LIN JiKeng YAN YiPeng PU TianJiao LUO ShanShan LIU Tao ZHENG WeiHong WANG XuDong Key Laboratory of Power System Simulation and Control of Ministry of Education(Tianjin University) Tianjin 300072China China Electric-Power Research institute Beijing 100192China Schneider Electric Co. Ltd(China)Shanghai BranchShanghai 200000China Tianjin Electrieal Power Corperation Tianjin 300010China

Electromagnetic transient simulation for large-scale power system is a time-consuming problem.A new frequency-dependent equivalence method is presented in the paper,which might significantly accelerate power system electromagnetic transient *** the method,an effective algorithm is designed to directly transfer the port admittance determinant of external system's mixing matrix into admittance rational function;and the step-by-step strategy for the equivalence of actual large system is put forward,which further reduces the calculation quantities ***,the study of multiple real root pole characteristics of admittance transfer function of two-port network is performed and a proposition is *** on the proposition and residue theorem,the equivalence system for external system corresponding to the admittance rational function is *** computation complexity of the step-by-step equivalence method is about o(┌n/np×T┐)(┌┐ is upper integral operation,n is the total buses number of external system,N P is the total buses number of single step equivalence network,T is single step equivalence time),which indicates that the computation complexity of the method proposed has nearly linear relationship with the buses number of external system,and the method proposed has satisfactory computation *** the mixing matrix of external system includes all the information of external system,therefore,port admittance rational function derived from it can reflect its full frequency characteristic and the equivalence network achieved has high equivalence ***,since the port rational function is gained at the condition of the external system without source,which equals stable passive network,it could not show any unstable pole and need not extra measure to make the equivalence system *** test results of the samples and comparison with other methods demonstrate that the new method proposed is valid and effective.

关键词： equivalence method electromagnetic transient simulation frequency-dependent rational functions mixing matrix

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Influence of the Structure Dimension of GIS on the Partial Discharge

Influence of the Structure Dimension of GIS on the Partial D...

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IEEE International Conference on Condition Monitoring and Diagnosis

作者： Dengwei Ding Wensheng Gao Weidong Liu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University

ISBN: (纸本)9781467310192

Partial discharge (PD) monitoring plays an important role in the online maintenance of the gas insulated switchgear (GIS). In recent years, the ultra high frequency (UHF) method for PD detection arouses great interest of many researchers because of the high sensitivity and anti-interference capability. The coupling of UHF signal is the key to the detection of partial discharge in GIS. The structure size of GIS has great impacts on the PD signal, because the cutoff frequency of the high order mode of the electromagnetic (EM) wave depends on the diameters of the inner conductor and enclosure. In this paper, the influence of the inner conductor diameter is investigated by varying the center conductor size. The inner coupler is adopted to receive the partial discharge signal, and two types of PD sources are tested in the experiment. Firstly, the amplitude and the duration of the time domain signal and the frequency spectrum are focused, and their variations with the size of inner conductor are analyzed. Besides that, In order to research the changes of the TEM mode component and the high order mode component, low pass (LP), band pass (BP) and high pass (HP) filters are applied to process the PD signals, and the cumulative energy rates are calculated to indicate the energy distribution. In addition, a simulation using the FDTD method is conducted for comparison with the experimental results, and it indicates that the results of experiment and simulation are almost consistent.

关键词： Partial discharge Ultra high frequency Structure size of GIS Frequency spectrum The cumulative energy rate FDTD

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power Losses in Two- and Three-Level Three Phase Photovoltaic Inverters Equipped with IGBTs

Power Losses in Two- and Three-Level Three Phase Photovoltai...

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International Conference on Electrical Machines and systems

作者： Zhiping Chen Liqiang Yuan Zhengming Zhao Xiaoying Sun State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University

ISBN: (纸本)9781467323277

To increase efficiency is an essential target in photovoltaic (PV) power generation system. The losses of the whole system consist of several parts. This paper focuses on the losses of the hard-switching devices. An improved method to calculate the device losses is proposed. And influences of different factors like DC link voltage, input power, switching frequency and power factor on the losses are considered. Then this paper compares the losses of conventional two-level inverter and of diode-clamped three-level inverter to provide the evaluation of power losses under different working conditions. This is helpful to design and optimize a certain PV inverter. Calculating results based on an actual three phase 10kW PV inverter are presented.

关键词： Loss-calculation IGBT Three-level Photovoltaic

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X-ray backlighting of wire expansion and plasma merging of z-pinch load with 10-40kA/wire

X-ray backlighting of wire expansion and plasma merging of z...

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IEEE International Conference on Plasma Science (ICOPS)

作者： Xinlei Zhu Xiaobing Zou Ran Zhang Shen Zhao Haiyun Luo Xinxin Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

It is well known that the evolution of wire array z-pinch load can be divided into several phases: wire explosion, inter-wire plasma merging, implosion and stagnation. In this paper, experiments with x-pinch backlighter to study the initial wire explosion and inter-wire plasma merging were performed on the pulsed power generator PPG-I at Tsinghua University. An x-pinch (13-25μm Mo and 5-18μm Wu wires) used as soft x-ray source was installed in the centre between the output main electrodes of PPG-I generator, and the object z-pinch load was installed in one of the return current posts. The object z-pinch load consists of 2-4 tungsten wires of 5-18 μm diameter, 12 mm long, and 2 mm spacing between wires. The evolution images of wire explosion and inter-wire plasma merging were recorded with high resolution x-ray film, which was covered with a mass step-wedge filter to calibrate the mass density distribution of wire explosion and inter-wire merging plasma. Based on extensive discharge tests, the time sequence of backlighting images of z-pinches was obtained. In the paper, we also discussed how to determine the interface between high-density wire core and low-density surrounding plasma, and then presented the expansion rates of high density wire core and the mass density distribution of inter-wire plasma under different z-pinch current.

关键词： Wires Plasmas Merging Explosions Educational institutions Generators Radio access networks

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