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2009 Asia-Pacific power and Energy Engineering Conference, APPEEC 2009

作者： Jianhua, Zhang Guohua, Zhang Manyin, Duan Jingyan, Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China State Intellectual Property Office of the PRC Beijing China

ISBN: (纸本)9781424424870

An integrated indices system for urban power grid security assessment is proposed, which includes five kinds of indices such as capability of supplying power safely, static voltage security, topological vulnerability, transient security and risk indices. The indices system can scientifically and fully reflect the security level of power grid and provide a quantitative base for the establishment of emergency management technology and measures. The traditional indices and methods for power system security assessment are improved and some indices are first proposed such as "number of lost components after N-K contingencies" and "the largest power supply region index". Based on utility theory and considering effects of external environment on failure probability of lines, risk indices are constructed including "overload risk index", "low voltage risk index", "voltage collapse risk index" and "angle instability risk index". power system security Assessment Indices Calculation and Analysis Software is developed, which provides an accessorial and practical tool for power system plan and operation. At last, one urban power grid is used as a research example and the results show effectiveness of the indices system and practicability of the software. © 2009 IEEE.

关键词： Risk management

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Fault Detection Based on Hierarchical Cluster Analysis in Wide Area Backup protection system

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Energy and power Engineering 2009年第1期1卷 21-27页

作者： Yagang ZHANG Jinfang ZHANG Jing MA Zengping WANG Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University

In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated quickly and defined exactly. In our study, global information will be introduced into the backup protection system. By analyzing and computing real-time PMU measurements, basing on cluster analysis theory, we are using mainly hierarchical cluster analysis to search after the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact detection of fault components and fault sections, and finally accomplish fault isolation. The facts show that the fault detection of fault component (fault section) can be performed successfully by hierarchical cluster analysis and calculation. The results of hierarchical cluster analysis are accurate and reliable, and the dendrograms of hierarchical cluster analysis are in intuition.

关键词： wide area backup protection phasor measurement unit PMU wide area measurement system WAMS fault detection cluster analysis

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Research on secondary arc for UHV transmission lines

Research on secondary arc for UHV transmission lines

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2009 Asia-Pacific power and Energy Engineering Conference, APPEEC 2009

作者： Song, Xiang Jun, Wen Hui-Yuan, Zhang Xiang-Ning, Xiao School of Electrical and Electronic Engineering North China Electric Power University Beijing China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Ministry of Education Beijing 102206 China

ISBN: (纸本)9781424424870

A dynamic mathematical model - Johns arc model which could be used to simulate the dynamic secondary arc in the process of single-phase auto-reclosure after transient single-phase faults is presented and actualized in PSCAD/EMTDC. This model is used in the digital faults simulations of the first Ultra high voltage (UHV) transmission line of 1000kv class in China-the Jindongnan-Jingmen UHV single circuit transmission project under construction, the outcomes and influences of several known important factors, such as wind, manner of shunt compensation and other meteorological and geographical factors including temperature, humility, altitude and so on are discussed. According to the discussion, the preconcert reclosure interval of 1s is proved to be proper. © 2009 IEEE.

关键词： Electric lines

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Applications of Data Mining Theory in Electrical Engineering

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Engineering（科研） 2009年第3期1卷 211-215页

作者： Yagang ZHANG Jing MA Jinfang ZHANG Zengping WANG Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University

In this paper, we adopt a novel applied approach to fault analysis based on data mining theory. In our researches, global information will be introduced into the electric power system, we are using mainly cluster analysis technology of data mining theory to resolve quickly and exactly detection of fault components and fault sections, and finally accomplish fault analysis. The main technical contributions and innovations in this paper include, introducing global information into electrical engineering, developing a new application to fault analysis in electrical engineering. Data mining theory is defined as the process of automatically extracting valid, novel, potentially useful and ultimately comprehensive information from large databases. It has been widely utilized in both academic and applied scientific researches in which the data sets are generated by experiments. Data mining theory will contribute a lot in the study of electrical engineering.

关键词： Fault Analysis Data Mining Theory Classification Electrical Engineering

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Classification and generalization of the load model based on model dynamic responses

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2009年第2期24卷 132-138页

作者： Zheng, Xiaoyu Ma, Jin He, Renmu Tang, Yonghong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Sichuan Electric Power Research Institute Chengdu 610072 China

The time-variable characteristic of the load is a limiting factor in the using of the load model. Load classification is a good approach to solve this problem. A new load model classification and generalization method is proposed in this paper. First, load model responses are chosen as the characteristic vectors in the cluster analysis. Then, the multi-curve identification technique is applied in building the load models for each class. Finally, more robust and practical models are obtained after the combination of classes, which are also verified by their strong generalization capability and physical interpretation.

关键词： Cluster analysis

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A novel method to rapidly identify inrush current and internal fault current based on variation characteristic of fundamental current amplitude

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2009年第6期24卷 166-171页

作者： Ma, Jing Wang, Zengping Wu, Jie Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Zhejiang Electric Power Design Institute Hangzhou 310014 China

A new transformer protection principle based on two-instantaneous-value-product algorithm to extract the feature of fundamental current amplitude is put forward in this paper. First, the algorithm of two-instantaneous-value-product is developed, and variation trends of fundamental current amplitudes are analyzed in the case of inrush currents and internal fault currents. Whether the fundamental current amplitude reveals the descending feature or not can be used to distinguish the inrush current and the internal fault. The computational simplicity of the proposed scheme enables its implementation in real-time applications with low-cost microprocessors. dynamic testing results indicate that this method is able to clear internal fault even light fault less than a cycle and can not be affected by the current transformer saturation. Moreover, compared with the second harmonic restraint principle and the waveform comparison principle, the proposed algorithm has better performance.

关键词： Transformer protection

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power system real-time state estimation and prediction based on WAMS

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Dianli Xitong Zidonghua/Automation of Electric power systems 2009年第16期33卷 35-39+49页

作者： Li, Hong Li, Weiguo Bi, Tianshu Xiong, Haoqing Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China Henan Electric Power Dispatching and Communication Center Zhengzhou 450052 China

A real-time state estimator based on WAMS is presented, in which the recursive extended least-squares algorithm is used to identify the state transition matrix, and the fading memory exponential weighted algorithm is employed to estimate the error covariance matrix of the linearized model. At the same time, the measurement weights are calculated on-line by the measurement standard deviations. When the filter is done by using observed data, the imprecise (or unknown) parameters and the noise covariance matrixes of the state estimation model are constantly identified and corrected on-line simultaneously, which makes the model follow the contingencies and the time-varying process adaptively. Therefore the estimated errors are reduced, and the filtering precision is high. Simulation results show that the proposed method has good performance under different scenarios such as normal operation, bad measurements, sudden load change/drastic generation variation and topology errors. This work is supported by Program for New Century Excellent Talents in University (No. NCET-05-0216). ©2009 State Grid Electric power Research Institute Press.

关键词： State estimation

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RETRACTED ARTICLE: Anti-islanding detection and protection for grid connected PV system using instantaneous power theory

RETRACTED ARTICLE: Anti-islanding detection and protection f...

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2009 International Conference on Industrial and Information systems, IIS 2009

作者： Wang, Fei Zhang, Chengcheng Mi, Zengqiang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China Foreign Language Teaching and Researching Department Hebei University Baoding 071000 Hebei Province China

ISBN: (纸本)9780769536187

Anti-islanding method with reliable protection and reasonable control run an important role in grid connected PV power generation system. The detection and calculation of real and reactive power are the bases of many inverter resident passive and active islanding detection method (IDM). As well as the detection and calculation of real and reactive power also concern with the inverter control of grid connected PV power generation system. In this paper, considering instantaneous voltage and instantaneous current are periodic function about time, think of it in terms of periodic function space to define the inner product and norm, Hilbert space based power theory is proposed. Real power, reactive power and apparent power in Hilbert space based theory are defined. This proposed Hilbert space based power theory provide a novel view for the protection, islanding detection and control of grid connected PV power generation system. © 2009 IEEE.

关键词： Electric power system control

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A novel algorithm of calculating the circulating current on the delta side of three phase wye-delta connected transformer

A novel algorithm of calculating the circulating current on ...

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

作者： Tao Zheng Qiang Liu Department of Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control China Electric Power University Beijing China

ISBN: (纸本)9781424452293

The circulating current on the delta side of wye-delta connected three-phase power transformer is hard to measure. The differential transformer protection has to adopt current phase compensation method to compensate the circulating current. However, the differential current hardly reflect the magnetic exciting current of transformer no matter what kind of current phase compensation methods used. It limits many algorithms of identifying inrush current, such as the promising one based on the equivalent instantaneous inductance. How to obtain the circulating currents in delta side has become a difficult problem in transformer protection. In this paper, based on the voltage equations of transformer, the calculation of the resistance and leakage inductance of winding is deduced. And then, a novel algorithm of calculating the circulating currents in delta side is proposed Simulation results of MATLAB verify the accuracy of this algorithm, which offers a new way to calculate the differential currents exactly.

关键词： power transformers Phase transformers Inductance Surge protection Equations Current measurement Asia power measurement Phase measurement MATLAB

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The finite elements analysis on magnetic field of controllable saturated reactor

The finite elements analysis on magnetic field of controllab...

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International Conference on power Electronics and Drive systems (PEDS)

作者： Wang Ziqiang Yin Zhongdong Yang Po Li Ke key Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control of Ministry of Education North China Electric Power University Beijing China Laboratory of Power System Protection and Dynamic Security Monitoring and Control of Ministry of Education North China Electric Power University Beijing China

In the power system, the controllable reactor can be used as reactive power compensation device to limit over-voltage operation, reduce no-load or light load loss and improve transmission capacity. It is with characters of simple structure, easy maintaining, low cost and high stability, etc. The magnetic field is closely related to the reactor performance. In this paper, aiming at a controllable saturated reactor prototype, using the finite elements method, the magnetic field is studied. Then, the precise 2-D prototype field-circuit coupling model is established based on the magnetic field analysis and the finite element analysis software - ANSYS. Using this model, the magnetic field and working currents concrete values under the condition that AC and DC excitations co-exist within the core are calculated. The analysis results indicate that finite element analysis theory can effectively analyze the magnetic field of the reactor.

关键词： Finite element methods Magnetic analysis Magnetic fields Inductors power system stability Software prototyping power system analysis computing Lighting control power system control control systems

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