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第七届亚太防雷国际会议

作者： Zhizhao Li Rong Zeng Zhanqing Yu Chijie Zhuang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department

Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission *** with the increase of operation voltage to 1000 kV and tower height to more than 100 meters, some shortcomings of the traditional EGM model were found by many *** Progression Model (LPM) was proposed to solve these *** some fundamental works, such as when the upward leader initiates and how it propagates, is still *** experiment was designed and implemented in this paper to simulate the electric field circumstance near the test transmission line while the lightning downward leader *** upward leader from the test transmission line was clearly *** inception voltage and characteristics was *** streamer and leader initiated from the ground wire and conductor bundle were *** experiment results show that the leader initiating from the ground wire is more active in the inception *** velocity of the upward leader acquired is about 1.2-3.0 cm/μs.

关键词： lightning shielding failure upward leader inception leader progression model simulating experiment

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Lightning overvoltage suppression of power transformer in UHV GIS by ferromagnetic ring

Lightning overvoltage suppression of power transformer in UH...

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2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Zhang, Xiao He, Jinliang 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)9781457714665

Lightning overvoltage protection is of great importance to the safety of UHV GIS. The widely used arresters can only suppress the magnitude of lightning overvoltage but lack efficiency on alleviating the steepness. In practice, insulation failure of UHV transformer is often reported. A new protection method is proposed in this paper using ferromagnetic ring as supplement to arresters to suppress lightning overvoltage in UHV GIS. Moreover, equivalent model based on the characteristic of ferromagnetic material and factual dimension of the ring is established for calculation. simulation of an actual 1000kV GIS is carried out to thoroughly evaluate the lightning overvoltage suppressing effect of ferromagnetic rings with different materials and structure dimensions. © 2011 IEEE.

关键词： power transformers

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Dimensionality reduction analysis in condition classification of prognostics

Dimensionality reduction analysis in condition classificatio...

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Applied systems Health Management Conference 2011: Enabling Sustainable systems, MFPT 2011

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

In order to maintain the separability of different fault onsets, more characteristic parameters need to be used to establish the feature space with multiple possible faults. Usually, the dimensions of feature space have a positive correlation with the number of faults. Describing multiple faults in visualization is more difficult and the classification bounds with hyperplanes are less convenient to realize. Therefore implementing dimensionality reduction approaches in original feature space is beneficial for fault diagnosis and prognostics. Multidimensional Scaling (MDS) has been widely studied and used for dimensionality reduction as well as Principal Component Analysis (PCA). When these methods are applied in the prognostics process, the effectiveness needs validation with the reason that the deterioration features in degradations are different from the faults onsets that in diagnostics. The paper analyzes the nonlinear dimensionality reduction methods including Self-Organizing Map (SOM) and Isometric feature mapping (Isomap). Based on the deterioration data in an engine, the effects of these methods are analyzed.

关键词： Self organizing maps

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Improved Blade Tip Timing in Blade Vibration Monitoring with Torsional Vibration of the Rotor

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Journal of Physics: Conference Series 2012年第1期364卷

作者： Chao Liu Dongxiang Jiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 People's Republic of China

Due to the complex conditions in rotating machinery, the blades usually encounter fluctuating loads, and failures may occur in the operation. Blade vibration is rarely monitored in the practical rotating machinery in power plants as the traditional blade vibration method using strain gauge method is hard to be applied in long-time and online monitoring. The blade tip timing method is a promising approach to monitor the blade vibration and several special sensors are developed to realize the online monitoring. Based on the traditional blade tip timing method, an improved approach is established in this work. The proposed method can modify the expected arriving time when the torsional vibration exists. The accuracy is therefore improved in the torsional vibration case. Then the blade vibration monitoring with the traditional blade tip timing method and the proposed method are carried out in the test rig in laboratory. The results validate that, the torsional vibration influences the expected arriving time, and the proposed method can modify the expected arriving time and improve the accuracy of the blade vibration monitoring.

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Applicable range analysis of optimized single-terminal fault location algorithm

Applicable range analysis of optimized single-terminal fault...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Huang, Tian-Xiao Dong, Xin-Zhou Shi, Shen-Xing Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

Impedance method and single terminal travelling wave method are analyzed in paper, applicable scope of optimized solution is presented. Impedance method is of high robustness but low accuracy. Single terminal travelling wave method offers high accuracy but poor robustness. Optimized solution combines these two methods together, takes advantages of both methods. It is a great enhancement to single terminal fault location. This paper analyzed theoretical basis of optimized solution, proposed the calculation algorithm of fault location range using impedance method. Analyses of impedance method and single terminal travelling wave method show that the optimized solution is suitable for engineering application. Error analysis is proved correct by simulation. © 2011 IEEE.

关键词： Location

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Single phase grounding fault location based on frequency domain characteristics of fault current

Single phase grounding fault location based on frequency dom...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Jiang, Bo Shi, Shenxing Dong, Xinzhou Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

This paper studies the fault current frequency spectrum characteristics of single phase ground fault in ungrounded distribution networks, and the fault location method based on it. Firstly, it analyzes the production mechanism of 2nd major frequency component, and the relationship between the 2nd major frequency component and series resonance frequency of the faulted line. Secondly, from the perspectives of lumped-parameter circuit, the relationship between 2nd major frequency component and fault location is deduced. simulation cases are used to confirm the relationship. Last, the impact of load and initial fault phase angle on the 2nd major frequency component are researched. simulation research proves the feasibility of the fault detection and location method based on frequency domain characteristics. © 2011 IEEE.

关键词： Electric fault location

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Research on the process of power flow transferring and its identification method

Research on the process of power flow transferring and its i...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Liu, Kun Dong, Xinzhou Wang, Bin Shi, Shenxing State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

This paper analyzes the general process of power flow transferring and divides it into four parts: 1) the process of first phase selection after fault occurs;2) the process of selective action at the first time;3) the process of second phase selection and status confirmation;4) the process after status confirmation. It points out that the issue of asymmetrical flow transferring is a critical process which must be put emphasis on. Then it proposes a method to identify this process, and discuss different solution methods. © 2011 IEEE.

关键词： Electric load flow

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Estimating the electromechanical oscillation characteristics of power system based on measured ambient data utilizing stochastic subspace method

Estimating the electromechanical oscillation characteristics...

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2011 IEEE PES General Meeting: The Electrification of Transportation and the Grid of the Future

作者： Jingmin, Ni Chen, Shen Feng, Liu State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781457710018

Estimating low-frequency oscillation modes and the corresponding mode shapes based on ambient data from WAMS measurements has a promising prospect of application in power system analysis and control. The present approaches estimate the modes and mode shapes respectively, which greatly reduce the computational efficiency. Besides, there is no good solution for the problem of discriminating real modes from the spurious ones caused by numerical error. A method based on stochastic subspace method was proposed in this paper. By choosing the angle measurements of all buses as input signals for the method, the modes and simultaneously the corresponding mode shapes of any bus can be estimated conveniently. By introducing the idea of reference channels, the computation complexity was substantially reduced without decreasing the accuracy. Stabilization diagrams technique was introduced to discriminate the real modes from the spurious ones. The test case based on the IEEE-118 system indicated that the method proposed is satisfying in respect of both computational efficiency and accuracy of results. © 2011 IEEE.

关键词： Computational efficiency

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A novel fault locator for power distribution system with neutral non-effectively grounded

A novel fault locator for power distribution system with neu...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Shi, Shenxing Dong, Xinzhou State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

Fault locator for power distribution system with neutral non-effectively grounded should locate phase-to-phase fault and single-phase-to-ground fault respectively. For phase-to-phase fault, the point can be located by power-frequency impedance. However, for single-phase-to-ground fault with limited power-frequency current not more than load current, a novel fault location technology should be developed. The paper will present a practical single-phase-to-ground fault location based on fault generated traveling waves acquired from one phase current transducer and zero sequence current transducer at first. Then implementation of the novel fault locator is proposed including hardware design and software flowchart. At last field tests will be made to verify the feasibility of the fault locator. © 2011 IEEE.

关键词： Transducers

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Analyses on frequency transmission characteristic of traveling wave in distribution power system

Analyses on frequency transmission characteristic of traveli...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Wang, Jun Shi, Shenxing Dong, Xinzhou Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

Under the skin effect caused by the alternating electromagnetic field, the transmission line parameters changes with frequency, and different line resistivity, surge impedance, wave speed are presented in one line under the different frequency bands of signal. This phenomenon is usually called Frequency transmission characteristic, which is mainly discussed in this paper. This paper first studied the line resistivity, wave speed and surge impedance of zero-mode component and line-mode component in different frequency bands. Then, the line structure and its effection on Frequency transmission characteristic are presented. Last, the frequency transmission characteristic on a certain line fault is discussed based on a typical distribution system model. The research in this paper is meaningful for future study on the fault feeder selection and fault location technology based on traveling wave in the distribution system. © 2011 IEEE.

关键词： Wavelet transforms

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