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作者： Xiao, Jun Zhang, Xuan He, Lin Lin, Li-Peng Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China Tianjin Electric Power Company Tianjin 300010 China

ISBN: (纸本)9781457700668

This paper introduces synergetic theory and proposes multi-path load forecasting automatically coordinated approach based on the maximum entropy principle. Taking the expectation and second order central moment of forecasted results into account and using the maximum entropy principle,this synergetic load forecasting method receives the probability distribution function of the forecasted values and obtains the final high, middle and low forecasting scheme based on the probability theory. Case study has shown the model and method mentioned above can take the affection of the conflicts among different forecasting path into account in forecasting, resulting in higher precision of load forecasting © 2010 Chinese Soc for Elec Eng.

关键词： Forecasting

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Discussion on setting calculation of loss-of-excitation protection for large turbogenerator

Discussion on setting calculation of loss-of-excitation prot...

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2010 International Conference on Electrical Machines and systems, ICEMS2010

作者： Yao, Siwang Wang, Weijian Luo, Ling Gui, Lin Qiu, Arui State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

Loss of excitation (LOE) is a common fault found in the generators. The most widely applied method for detecting a generator loss of excitation is the use of impedance relays to sense the variation of impedance as viewed from the generator terminals [1]. However, compared with China's approachs, in the setting of impedance circle, the IEEE's allow the circle to extend along the negative X axis, meanwhile, in the latest edition of the "IEEE Guide for AC Generator Protection", the circle is further extended, reaching to -1.25X_d.We think this is adverse, to prove our point, the paper ,basing on the IEEE 9 bus model and using computer digital simulation, have studied various loss-of-excitation conditions and some system disturbances that may lead to the relay false tripping. simulation results indicate that the IEEE's method not only can't accelerate the operation effectively, but also will increase the chances of maloperation.

关键词： Impedance Generators Relays Analytical models power system stability Reactive power

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Habitat suitability model of the four major Chinese carps

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Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering 2011年第SUPPL. 1期19卷 123-129页

作者： Yi, Yujun Zhang, Shanghong Ministry of Education Key Laboratory for Water and Sediment Sciences Beijing Normal University Beijing 100875 China State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China Renewable Energy School North China Electric Power University Beijing 102206 China

Coupling habitat suitability function of carps spawning sites with one-dimensional mathematical model, a Habitat Suitability Index (HSI) model to calculate the habitat suitability indices for the four major Chinese carp species was developed. The model was validated by measured data. Using the Habitat Suitability Index model of the four major Chinese carps, the stream habitat for the carp species under different hydraulic condition were assessed. Minimum instream flow and suitable daily discharge increase during the reproduction season for the carp species were suggested. The minimum discharge needed for the four major Chinese carp species in the middle reach of the Yangtze River is 3000 m3/s. Different daily discharge increases are required for different initial discharges. When the initial discharge is 4000 m3/s, the optimal daily discharge increase is approximately 500 m3/(s. d);and when the initial discharge is 9000 m3/s, the optimal daily discharge increase is approximately 800 m3/ (s. d);when initial discharge is 15000 m3/s, the optimal daily discharge increase is approximately 1000 m3/(s. d). Too small or too large of a daily discharge increase is not good for carps spawning.

关键词： Functions

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Application of automatic differentiation technique to the transient simulation of distributed generation system

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Dianli Xitong Zidonghua/Automation of Electric power systems 2010年第23期34卷 71-75+101页

作者： Wang, Chengshan Huang, Bibin Li, Peng Gao, Fei Ding, Fei Ding, Chengdi Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China

In view of the diversity of the distributed generation control system and the influence on the simulation efficiency due to adoption of the user-defined model based on the basic elements of control systems, a control system compositional modeling method is proposed that consists in combining the basic elements into a number of functions. The corresponding compositional function values and derivatives can be accurately and highly efficiently found using the automatic differentiation technique, effectively increasing the computational efficiency of the simulation program while maintaining the code maintainability and scalability. This method is validated with an example. © state Grid Electric power Research Institute Press.

关键词： Distributed power generation

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Study on transferred lightning overvoltage in microgrid

Study on transferred lightning overvoltage in microgrid

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Asia-Pacific International Symposium on Electromagnetic Compatibility

作者： Hongqiao Yu Shuiming Chen Pengcheng Yang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University

ISBN: (纸本)9781424456215

If the microgrid is stroke by lightning, the lightning overvoltage which transferred though distribution transformer has great influence on the safety of the microgrid. The models of microgrid and high-frequency transformers are established based on the electromagnetic transient calculation program PSCAD/EMTDC. The transferred overvoltage with different lightning strike position in microgrid is researched in this paper. The effect of surge arresters on restricting overvoltage is also analyzed. The simulation results show that surge arresters must be installed at both sides of transformer due to the high overvoltage when the transformer has no load. If the transformer is connected with cables, the overvoltage will be reduced. The longer the cable is, the lower the overvoltage is. The types of loads have a little influence on the overvoltage.

关键词： Lightning Voltage control power transformer insulation Frequency Capacitance Laboratories power system simulation power system modeling power generation Electromagnetic modeling

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Study on lightning protection of cables and transformer in Microgrid

Study on lightning protection of cables and transformer in M...

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China International Conference on Electricity Distribution, CICED

作者： Hong-qiao Yu Shui-ming Chen Yang Peng-cheng State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457700668

The cable and transformer are important distribution equipment in Microgrid. Due to the low insulation level, the insulation of them is easily damaged by lightning. The models of high-frequency transformer and the calculation model of induced lightning with transmission line based on electromagnetic transient calculation software PSCAD / EMTDC are designed in this paper. The lightning protection of cables and transformer in Microgrid, the transferred overvoltage of transformer and the effect of the length of cables and the load types to overvoltage level are researched. The conclusion shows that the induced overvoltage and transferred overvoltage could be reduced efficiently after installing surge arrester at the cables and transformer, but the direct lightning overvoltage is not reduced in the safety range; The longer the cables, the lower the overvoltage is; The inductively load can reduce the overvoltage level slightly while the capacitive and resistance loads has no influence.

关键词： power cables Load modeling Arresters Cable insulation EMTDC Lead PSCAD

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Integration of protection and control systems for smart substation

Integration of protection and control systems for smart subs...

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2010 5th International Conference on Critical Infrastructure, CRIS 2010

作者： Ma, Jing Wang, Tong Wu, Jie Wang, Zengping Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University 102206 Beijing China State Nuclear Electric Power Planning Design and Research Institute 100094 Beijing China

ISBN: (纸本)9781424480814

Digital based data processing and protection and control system along with digital communication networks introduces new structures for substation protection and control systems and new methods for intelligent protection and control systems. This paper presents a unique vision for the future integration of protection and control systems. Firstly, the basic concept and configuration of the developed protection and control systems for smart substation is introduced. The features and functions of integrated protection and control systems for smart substation are then discussed and compared with that of the traditional substation in detail. © 2010 IEEE.

关键词： Data handling

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Cascaded battery energy storage system based on dual active bridges and a common DC bus

Cascaded battery energy storage system based on dual active ...

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International power Engineering Conference (IPEC)

作者： Yiding Jin Qiang Song Wenhua Liu Weixin Sun State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic devices connected. Moreover, the occupancy and noise of industrial frequency transformers also become restraints to the promotion of urban network energy storage. For that reason, this paper proposes a battery energy storage system based on cascaded dc-ac converter, dual active bridges, and a common dc bus. High frequency transformers are used to replace the industrial frequency transformer for insulation, and battery groups are connected to the common dc bus with respective dc-dc interfaces. This multilevel converter system is easy to modularize, easy to extend, and allows different kinds of batteries to work together. The main circuit and proper control system are designed, with the soft-switching condition and current control issues of the dual active bridge analyzed in detail. The simulation results from EMTDC model verify the operation principles and corresponding control strategies.

关键词： Batteries Voltage control Converters Switches Bridge circuits

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Basic principles of hybrid excitation PM synchronous generator utilizing harmonic for excitation

Basic principles of hybrid excitation PM synchronous generat...

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作者： Xia, Yonghong Wang, Shanming Ma, Mingyuan Hao, Liangliang Qiu, Arui Huang, Shaogang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Department of Electrical and Automatic Engineering Nanchang University Nanchang Jiangxi 330031 China

ISBN: (纸本)9788986510119

A novel method, which utilizes harmonic for excitation, is presented to adjust the air-gap magnetic field for permanent magnet synchronous machine. The structure and basic principles of the hybrid excitation PM synchronous generator(HEPMSG) are introduced. The no-load and on-load electromagnetic field are calculated based on finite element method, and the waveform and effective value of the winding voltage and characteristics of the machine are gained for different loads. Calculation results demonstrate the new hybrid excitation scheme is feasible. This new method combines the advantages of PM machines and electrical excitation machines. The machine removes the brushes and slip rings, which makes permanent magnet machine keep simple and highly reliable.

关键词： Synchronous generators

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Notice of Retraction: The Optimal Bidding Based On The Prospect Theory

Notice of Retraction: The Optimal Bidding Based On The Prosp...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Ji-keng Lin Xudong Wang Key laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

This article has been retracted by the publisher.

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