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2009 IEEE power and Energy Society General Meeting, PES '09

作者： Yanan, Zheng Ming, Zhou Gengyin, Li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Changping 102206 Beijing China

ISBN: (纸本)9781424442416

With the development of electricity demand side market, large consumers have more electricity purchase choices, in the same time have to face the risk of electricity price fluctuation on different markets. In order to measure and hedge the risk reasonably, this paper introduces information entropy as the measure to risk in electricity purchase, by aid of fuzzy optimization, linear membership function is adopted and the optimal electricity purchasing portfolio model is established according to the given expected target and tolerance. Test results show that information entropy can overcome lots of shortages in the method that adopts variance as risk measure;the electricity purchase strategy given by fuzzy optimization has good consideration both on price and risk. ©2009 IEEE.

关键词： Sales

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Fault diagnosis based on cluster analysis theory in wide area backup protection system

Fault diagnosis based on cluster analysis theory in wide are...

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

作者： Zhang, Yagang Ma, Jing Zhang, Jinfang Wang, Zengping Key Laboratory of Power System Protection and Dynamic Security Monitoring Control under Ministry of Education North China Electric Power University Baoding 071003 China

ISBN: (纸本)9781424424870

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 researches, global information has been 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 technology to seek after for the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact identification of faulty components and faulty sections, and finally accomplish fault isolation. Multivariate statistical analysis theory is an efficient theory that can resolve different kinds of complex problems. It has been applied successfully in many researches of various fields, such as geology, weather, hydrology, iatrology, industry, agriculture, and economy, etc. In the study of electric power systems, multivariate statistical analysis theory must also have a good prospect of application. © 2009 IEEE.

关键词： Cluster analysis

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Design of PV array model based on EMTDC/PSCAD

Design of PV array model based on EMTDC/PSCAD

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

作者： Xue, Jinhui Yin, Zhongdong Wu, Bingbing Peng, Jun Key Laboratory of Power System Protection and Dynamic Security Monitoring Control under Ministry of Education North China Electric Power University Beijing 102206 China

ISBN: (纸本)9781424424870

Along with consuming of fossil energy step by step, crisis of energy has been appeared. The solar energy, which is endless, is a kind of renewable energy. Radiation of sun coming to earth in a day is equal to the energy, which is released by trillion buckets of oil. The research of solar energy generation has stepped into a very activity period. This paper analyses the physics characteristic of photovoltaic array firstly, then researches the mathematical model applying in engineering, and designs the total simulation model based on power electronic circuit in the end. In order to validate the correctness and validity, this paper makes a simulation as an example. The scheme can express the V-I characteristic of photovoltaic array very well. © 2009 IEEE.

关键词： Solar energy

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Technology research of novel energy storage control for the PV generation system

Technology research of novel energy storage control for the ...

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

作者： Xue, Jinhui Yin, Zhongdong Wu, Bingbing Wu, Ziping Li, Jun Key Laboratory of Power System Protection Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 China

ISBN: (纸本)9781424424870

Recent years, technologies for new energy have developed rapidly since the energy crisis and the environmental pollution got worse. And the solar energy generation technology tends towards the stage of a large number of applications in engineering from the research stage. This paper designed a grid-connected PV system firstly, then introduced the operation principle of the various parts as well with the control strategy of the power flow. The design of energy storage is of great significance as the output power of PV cells array is greatly affected by the light intensity and the temperature change. Battery is used as the energy storage device normally in the traditional energy storage system. In this paper, it used the Ultracapacitor as the energy storage device after comparing with the battery, and designed the charge-discharge control strategy according to the characteristics of the Ultracapacitor. Finally it verified the feasibility of the energy storage control strategy through the simulation models which was built based on the PSCAD/EMTDC platform. © 2009 IEEE.

关键词： Supercapacitor

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The research on the characteristic of fault current of doubly-fed induction generator

The research on the characteristic of fault current of doubl...

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

作者： Ao-Yang, Han Zhe, Zhang Xiang-Gen, Yin Key Laboratory of Power System Protection and Dynamic Security HuaZhong University of Science and Technology China

ISBN: (纸本)9781424424870

Recent years, more and more wind power plants with the doubly-fed induct generation (DFIG) are built in China. With the development of the distributed sources, it was critical to present the new protection schemes and the key point is understands the characteristics of DFIG fault current. Because the complex in the generator's structure, the related references about this topic were relatively less. The DFIG generator has a three-phase wound rotor, which was supplied by a pulse width modulation (PWM) converter. When a fault occurs, the transient process was not only determined by machine itself but also the outer exciting system. So the waveform of fault current has variety. Only use the theory analysis was hard to describe the characteristic of fault current. The author adopt the simulation method combined theoretical analysis to investigate short-circuits current. In order to delineate various waveforms of current accurately, the emphasis lay on building the whole system model completely and precisely. This paper first analyzed the component of fault current in theory, and then built the specific model of rotor side exciting PI controllers and the active crowbar protections. Based on the various fault current waveforms, the characteristic of fault current were presented at last. © 2009 IEEE.

关键词： Wind power

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RETRACTED ARTICLE: Passive islanding detection method for grid connected PV system

RETRACTED ARTICLE: Passive islanding detection method for gr...

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2009 International Conference on Industrial and Information systems, IIS 2009

作者： Wang, Fei Mi, Zengqiang Key Laboratory of Power System Protection Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China

ISBN: (纸本)9780769536187

Passive islanding detection method is an important concern for grid connected photovoltaic (PV) power generation system due to personnel and equipment safety. Over/Under Voltage protection (OVP/UVP) and Over/Under Frequency protection (OFP/UFP) are basical inverter resident passive islanding detection method (IDM) for detecting an islanding condition by monitor parameters in Point of Common Coupling (PCC) such as voltage amplitude and frequency and then cause the inverter to shut down when there is sufficient transition from normal specified conditions. The real and reactive power equations and Non-Detection Zone (NDZ) of OVP/UVP and OFP/UFP methods for grid connected PV system are derived and analyzed in this paper. Analyses show that the behavior of the system at the time of disconnection will depend on the imbalance power at the instant before the switch opens to form the island, these results also indicate the NDZ of OVP/UVP and OFP/UFP methods is considerable large and the reaction times for these protective methodologies may be variable or unpredictable. © 2009 IEEE.

关键词： Distributed power generation

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Indices system and methods for urban power grid security assessment

Indices system and methods for urban power grid security ass...

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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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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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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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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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