检索结果-内蒙古大学图书馆

Residual voltage transformation method for short-circuit current calculation with matrix transformation

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical engineering 2005年第23期25卷 61-65页

作者： Jiang, Tong Bai, Xue-Feng Guo, Zhi-Zhong Lu, Ying Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China School of Electrical Engineering and Automation Harbin Institute of Technology Harbin 150001 China Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

Unbalanced element brings a big problem to fault analysis of symmetrical components method. According with fault analysis of phase components, a residual voltage transformation method for short-circuit current calculation is presented with matrix translation in the place of classical sequence networks connection, which is suitable for both phase coordinates and symmetrical components coordinates. Calculation formulas are proposed with matrices calculation to deal with unsymmetrical faults and parameter matrices for various faults are listed. Analysis of simultaneous faults with unbalanced parameter element is done without calculation qualities increased. Simple examples have shown that the method is practical and suitable for programming.

关键词： Short circuit currents

来源：评论

学校读者我要写书评

暂无评论

Snubberless switching-off characteristics of IGCTs equipped in high power three-level neutral point clamped converters

Snubberless switching-off characteristics of IGCTs equipped ...

引用

International Conference on Electrical Machines and systems (ICEMS)

作者： Liqiang Yuan Zhengming Zhao Haitao Zhang Zhi Yang Bing Li Jianzheng Liu Department of Electrical Engineering Tsinghua University Beijing China Department of Frequency-Converter and Control System Guodian Nanjing Automation Company Limited Nanjing China

Along with the improved design and broad applications of multi-level topologies, as a new commercial power switch device in recent years, IGCT has led the rapid development of high power converters in many applications, such as medium voltage adjustable speed drive and FACTs. Since the power electronic device is the base of these converters, the switching-off characteristics of IGCTs have become one of the key points in converters' design and analysis, especially when snubber circuits are absent. This paper focuses on the snubberless switching-off characteristics of IGCTs equipped in the high power three-level neutral point clamped (NPC) converter. According to the physical characteristics of switch devices and commutating mechanism between different switching processes in the converter, the switching-off characteristics of IGCTs in different topology positions under different switching conditions are described, simulated and tested. The results of simulation and experiments are compared, especially the voltage spikes by IGCTs' switching off. The relation between the switching-off characteristics and the other elements of the converter is also discussed in detail, such as topology position, PWM strategy and mechanical structure. Finally, some helpful conclusions for high power converters' design and analysis are drawn

关键词： Switching converters Circuit topology Switches Medium voltage Variable speed drives Power electronics Switching circuits Snubbers Testing Pulse width modulation

来源：评论

学校读者我要写书评

暂无评论

The research of electric appliance running status detecting based on DSP

The research of electric appliance running status detecting ...

引用

2005 IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Li, Baoshu Quan, Chao Zhao, Shutao Tong, Weiguo Tao, Peng Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003Hebei Province China Electrical Engineering Department North China Electric Power University Baoding 071003 China North China Electric Power University Baoding 071003 China

ISBN: (纸本)0780391144

A new load detection method was presented based on its running status of Power system. The loads are sorted according to their index of capacitive, inductive, and none-linear. The static character of each load was got according to the time-distribution. The concept of load detection is completed. The data-sample and wave recording equipment is designed and assembled based on the DSP for power loads status detecting. The superior software was designed for data management and analyzing. The recognizing status data was analyzed in both time-domain and frequency-domain;the identifying method for electric power loads status is deduced based on the correlation coefficient;the mathematical model for the status identifying is built;the trueness and validity of the methods is verified based on the testing and analyzing. © 2005 IEEE.

关键词： Electric power systems

来源：评论

学校读者我要写书评

暂无评论

Unknown Input Detection Using Receding Horizon Approach

Unknown Input Detection Using Receding Horizon Approach

引用

IEEE International Symposium on Intelligent control (ISIC)

作者： B. Kulcsar J. Bokor Department of Transport Automation Faculty of Transportation Engineering Budapest University슠of슠Technology슠and슠Economics Budapest Hungary System and Control Laboratory Computer and Automation Research Institute Hungarian Academy of Sciences (ATOMKI) Budapest Hungary

The paper offers the possibility of the design of unknown input detection for dynamic systems under external noise effect. The presented geometric based fundamental problem in residual generation (FPRG) method uses on the one hand the Kalman filtering and on the other hand the moving horizon estimation (MHE) when stochastic noise on the input and on the output, with additive failure directions, are presents. The paper combines the optimal Kalman and MHE method with geometric based unknown input observer strategy. The MHE solution makes to treat constraints during the estimation process possible. A numerical example supports the necessity of constrained unknown input estimation

关键词： Fault detection State estimation control systems Kalman filters Space technology Additive noise automation Stability Predictive models Predictive control

来源：评论

学校读者我要写书评

暂无评论

A new ultra high-speed protection scheme based on wavelet analysis

A new ultra high-speed protection scheme based on wavelet an...

引用

International Power engineering Conference (IPEC)

作者： Ming-yu Yang Wan-ye Yao Zeng-ping Wang Ju Zhang Yan-jun Jiao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China Automation Department North China Electric Power University Baoding Hebei China

ISBN: (纸本)9810557027

A new ultra high-speed protection scheme is proposed in this paper. Using wavelet transform with multiresolution analysis, the current signals is decomposed into a series of detailed wavelet components. The spectral energies of the wavelet components are calculated and then employed to detect the faults. Characteristics of the proposed ultra high-speed protection algorithm are analyzed and results of simulation studies are given. The results show that the proposed algorithm is promising and easy to implement for computer relaying application

关键词： protection Wavelet analysis Wavelet transforms Multiresolution analysis Fault detection Algorithm design and analysis Computational modeling Analytical models Computer applications Protective relaying

来源：评论

学校读者我要写书评

暂无评论

A new protection algorithm for EHV transmission line based on singularity detection of fault transient voltage

A new protection algorithm for EHV transmission line based o...

引用

International Power engineering Conference (IPEC)

作者： Ming-yu Yang Wan-ye Yao Zeng-ping Wang Yan-jun Jiao Ju Zhang Key Laboratory of Power System Protection and Dynamic Security Monitoring Control under Ministry of Education North China Electric Power University Baoding Hebei China Automation Department of North China Electric Power University Baoding Hebei China

ISBN: (纸本)9810557027

A new non-unit voltage protection algorithm for extra high voltage (EHV) transmission lines is presented in this paper. The singularity of fault transient voltage signals in one terminal is utilized to discriminate clearly between internal and external faults. Lipschitz exponent (LE) is obtained from wavelet modulus maximum to detect singularity of signals. A typical 500 kV EHV transmission system has been simulated by ATP to evaluate the scheme. The simulation results show that this scheme is capable of providing correct responses under various system configurations and fault conditions

关键词： Transmission lines Fault detection Power system transients Voltage Power system protection Power transmission lines Wavelet transforms Circuit faults Signal detection Frequency

来源：评论

学校读者我要写书评

暂无评论

Power Quality Disturbance Detection Based on Mathematical Morphology and Fractal Technique

Power Quality Disturbance Detection Based on Mathematical Mo...

引用

IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Gengyin Li Ming Zhou Yan Luo Yixin Ni Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong China

Based on mathematical morphology and grille fractal, a novel approach on power quality disturbance detection and location is presented in this paper. At first a parallel composite morphological filter with multiple-structure elements is designed to filter the random noise and impulse noise in power quality disturbance signals. Then to the filtered curves, an easy implementation criterion for singularity detection based on the change regularity of grille fractal is proposed to locate the start and end time that disturbance occurs. The voltage sag, swell, harmonic and their combined disturbances are used to verify the validity of the proposed filter-location approach. Numerical results show that the proposed approach is valid and effective

关键词： Power quality Morphology Fractals Power harmonic filters Signal sampling Signal analysis Shape Educational programs Noise shaping Voltage fluctuations

来源：评论

学校读者我要写书评

暂无评论

Risk Management on Long-term Electricity Purchase Allocation in China Power Markets

Risk Management on Long-term Electricity Purchase Allocation...

引用

International Conference on Power Electronics and Drive systems (PEDS)

作者： Ming Zhou Gengyin Li Yanli Nie Yixin Ni Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry ofEducation North China Electric Power University Baoding Hebei China Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong China

This paper presents an integrated framework for the optimal management of electricity purchase allocation and risk for load service entities (LSEs). To the practice of China Power Markets, we propose the framework of power portfolio of combined physical forward contract and spot market. The framework suggests that the forward contracts should have different prices on-peak and off-peak in accord with sale prices distinguish on-peak and off-peak. The optimal purchase problem is described by the utility maximum integrated the rate of return and risk tolerance level, and risk is evaluated by Value at Risk (VaR). The analytical solution is also conducted. The numerical results are reasonable with higher rate of return and better risk hedging compared with the corresponding results from the existing portfolio selection approach. The presented framework gives one possible and effective method for the optimal power portfolio and risk management in incomplete power markets.

关键词： Risk management Power markets Portfolios Forward contracts Electricity supply industry Pricing Marketing and sales Energy consumption Power generation Scheduling

来源：评论

学校读者我要写书评

暂无评论

Optimizing the structure of hierarchical mixture of experts using genetic algorithms

Optimizing the structure of hierarchical mixture of experts ...

引用

2004 2nd International IEEE Conference 'Intelligent systems' - Proceedings

作者： Karras, Dimitrios A. Vlitakis, Constantinos E. Boutalis, Yiannis S. Mertzios, Basil G. Chalkis Institute of Technology Dept. Automation Hellenic Open University Rodou 2 Ano Iliupolis Athens 16342 Greece Democritus University of Thrace Dept. Electrical Engineering 67100 Xanthi Greece Department of Automation Thessaloniki Inst. Technol. Thessaloniki Hellas Democritus University Lab. of Automatic Control System Xanthi Hellas

ISBN: (纸本)0780382781

This study is an effort to give a practical solution in the problem of optimizing the structure of the Hierarchical Mixture of Experts model, which is a natural extension of the Associative Gaussian Mixture of Experts system. We present two novel methods for optimizing such structures using Genetic Algorithms. Special concern is taken for reducing the computational time so as to efficiently allow the structure to "grow" while it evolves with the Genetic Algorithm. The main contribution of the paper lies on the efficient, topologically oriented, representations of such architectures so as to be optimized through involving genetic algorithms.

关键词： Expert systems

来源：评论

学校读者我要写书评

暂无评论

Multilevel validation of online monitor for hard real-time systems

Multilevel validation of online monitor for hard real-time s...

引用

International Conference on Microelectronics, MIEL

作者： M. Jevtic V. Zerbe S. Brankov Department of Electronics. Faculty of Electronic Engineering University of Nis Nis Serbia Department of System and Control Theory Faculty of Automation and Informatics Technische Universität llmenau Llmenau Germany

To achieve the required performance of complex electronic systems it is necessary to validate the system function during all phases of the design, which means multilevel validation. A hybrid Online Monitor for hard real time systems (HRTS) has been developed. A special attention was dedicated on the multilevel validation in all phases of the design.

关键词： Monitoring Real time systems Hardware system testing Kernel Runtime Automotive engineering Electrical equipment industry Automobiles Circuit faults

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：