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Novel Connection Scheme of Backup power Supply Adaptive to Distribution Line Non-Communication Protection and New Criterion for High Voltage and Large Capacity Induction Motor

Novel Connection Scheme of Backup Power Supply Adaptive to D...

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

作者： Kun Liu Xinzhou Dong Zhiqian Bo State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China AREVA T&D Automation슠and Information Systems Stafford UK

This paper presents a new practical backup power supply connection scheme for distribution line non-communication protection (DNCP). simulation tests have been conducted using the alternate transient program (ATP) with respect to a typical single circuit breaker multi-section system. The results prove that the new scheme is able to not only recover the power supply of loads on healthy lines automatically, but also create disturbances in favor of accelerated over current (AOC) criterion. Aiming at the failure of directional under voltage (DUV) criterion derived from high voltage and large capacity induction motor load, a novel criterion using the increment of reactive power is proposed.

关键词： Emergency power supplies Voltage Induction motors power system protection Circuit testing Circuit simulation System testing power system transients Circuit breakers power supplies

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Transient stability assessment based on 2D combined attribute decision tree

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第SUPPL. 1期29卷 17-24页

作者： Wang, Kang Sun, Hong-Bin Zhang, Bo-Ming Wu, Wen-Chuan Jiang, Wei-Yong State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

A method for the power system transient stability assessment based on 2D combined attribute decision tree was proposed. Different from single attribute decision trees, the 2D trees combine two attributes as one automatically to improve its classifying ability in case of multi-dimension and nonlinear border among classes. In the proposed 2D tree, Gini coefficient based 2D combined splitting criterions was adopted and search method for splitting line in an inverse direction was developed. Case study was carried out in one-machine infinite bus system, IEEE 39-bus system and a real provincial system. Results show that, 2D combined attribute decision trees generated by the proposed method are smaller in structure, have the higher accuracy and generalization ability than that generated by the single attribute decision trees. Meanwhile, some important relationship between physical variables in power systems can be mined by the proposed method. Advantages mentioned above make that the proposed method is potential for real-life power system applications. © 2009 Chin. Soc. for Elec. Eng.

关键词： Decision trees

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Lightning protection study of transmission line, Part II: Analysis methods

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Gaodianya Jishu/High Voltage Engineering 2009年第12期35卷 2910-2916页

作者： Zeng, Rong He, Jin-Liang Chen, Shui-Ming State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

Design is the key of lightning protection of transmission lines, and lightning protection analysis is the base to estimate the lightning protection behaviors of transmission line and the effect of lightning protection measures for transmission line. We mainly discussed the development states and the existed problems in lightning protection analysis of transmission line in the world, presented the analysis methods on the lightning backflash and shielding failure of transmission line and their comprehensive applications, and proposed the suitable models and methods for lightning protection analysis of transmission line. The whole-wave- progress analysis model should be applied to calculate the lightning transient characteristics of transmission line when the lightning strikes the tower or the overhead ground wires of transmission line;different analysis methods, such as electrogeometric method, the leader propagating model and the fractal model, should be used to calculate the shielding failure behaviors of transmission line. The lightning protection analysis of transmission lines should consider the micro-typological characteristics and the area difference of lightning parameters along transmission line, and comprehensively estimate the lightning protection behaviors of transmission line sections.

关键词： Electric lines

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Lightning protection study of transmission line, Part III: Protection measures

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Gaodianya Jishu/High Voltage Engineering 2009年第12期35卷 2917-2923页

作者： He, Jin-Liang Zeng, Rong Chen, Shui-Ming State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

The lightning accidents threaten the safe operation of power system. We comprehensively analyzed the developing states, the existed problems in analysis methods and measures of transmission line lightning protection, and discussed the key issues of transmission line lightning protection in China that should be studied. The lightning protection measures are divided into back-up type and leading-type methods, so-called back-up type method is used in lightning protection of transmission line in China, which complicates lightning protection;but the so-called leading-type method is used in other countries, which simplifies lightning protection. The lightning protection measures for different sections of transmission lines should be comprehensively estimated and proposed by considering the micro-topographical feature and the regional performances of lightning parameters along transmission line. The lightning protection should be fully considered in transmission line design, reducing shielding angle of overhead wire, decreasing grounding resistances of tower footings, and suitably installing line surge arresters are fundamental methods of lightning protection of new transmission line.

关键词： Electric lines

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Lightning protection study of transmission line, Part I: Lightning parameters

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Gaodianya Jishu/High Voltage Engineering 2009年第12期35卷 2903-2909页

作者： Chen, Shui-Ming He, Jin-Liang Zeng, Rong State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

Obtaining actual lightning parameters is the fundament of lightning protection of transmission lines. Based on the comprehensive analysis on the methods to acquire lightning parameters, we analyzed the current research states and existed problems of lightning parameters, including annual lightning day, ground flash density, magnitude and waveform of lightning current. The lightning activities have obvious topographical feature, presently the lightning location system (LLS) should be fully applied to acquire the annual lightning day, ground flash density, magnitude of lightning current in different areas. Moreover, the monitoring devices of lightning current should be installed on typical transmission towers with different voltage grades in different areas to obtain the characteristics of real lightning current waveforms and magnitudes, and calibrate and check the lightning current magnitudes obtained from LLS. All these would make the lightning protection of power system focusing on the actual targets. Four sets of the developed monitoring devices of lightning current were installed, and the first lightning current waveform in China, which was similar to the standard waveform recommended by CIGRE, was recorded.

关键词： Electric lines

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Effect of surface topography and morphology on space charge packets in polyethylene

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Journal of Physics: Conference Series 2009年第1期183卷

作者： Zhou Yuanxiang Wang Yunshan Wang Ninghua Sun Qinghua State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China China Electric Power Research Institute Haidian District Beijing 100085 China

Polyethylene (PE) is a major kind of internal insulating material. With great progresses of space charge measurement technologies in the last three decades, lots of researches are focused on space charge in PE. The heat pressing and annealing condition of polyethylene affect its morphology obviously. During the heat pressing, the surface of PE forms different surface topographies because of different substrate materials. Surface topography has great relation to the epitaxial crystallization layer and influences the space charge characteristic of PE dramatically. This paper studied the formation process of different surface topographies and their micrographic characters in low density polyethylene (LDPE). pulsed electro-acoustic (PEA) method was used to measure the space charge distribution of samples with different surface topographies and morphologies in LDPE. The effect of surface topography and morphology to space charge packet were studied. The surface topography has great influence on space charge packet polarity and morphology has influence on both movement speed rate and polarity of space charge packet.

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Analysis of electrical tree ageing in silicone rubber by physicochemical approach

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Journal of Physics: Conference Series 2009年第1期183卷

作者： Y X Zhou Q Nie Z Z Chen R Liu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Department of Electrical Engineering Zhengzhou University Zhengzhou 450001 China

In this paper, the characteristics of electrical tree ageing in silicone rubber (SIR) under AC voltage were studied. The electrical tree initiation rate is 20% after the application of 6 kV AC voltage for 1000 hours. Samples are separated into three kinds according to processes of electrical tree formation: virgin samples without voltage application, non-treed samples without electrical tree formation after 1000 hours and treed samples with electrical tree formation after 1000 hours. Certain physicochemical diagnostic tests were carried out to understand the degradation of material, ascribed to long-time voltage application, using differential scanning calorimetry (DSC) and thermogravimetric-differential thermal analysis (TG-DTA). Physicochemical analyses, especially the DSC results, show that no additional phases are formed in the processes of electrical tree ageing in SIR. Reduction of the melting point and crystallinity of SIR is observed in the sequence of virgin samples, non-treed samples and treed samples. The activation energy values were calculated from the TG-DTA data. Compared to virgin samples, obvious reduction of activation energy value is observed in non-treed samples. Degradation in SIR has already occurred before electrical tree formation and charge injection and extraction by high field electrode under AC voltage is regarded as the reason.

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A novel modbus RTU-based communication system for adjustable speed drives

A novel modbus RTU-based communication system for adjustable...

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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Sideng, Hu Zhengming, Zhao Yingchao, Zhang Shuping, Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781424418497

The communication protocol is important for applying adjustable speed drive (ASD) systems to an industry network. This paper proposes a novel scheme of communication system for the ASD system based on Modbus protocol. The most remarkable advantage of the approach lies in the tradeoff between performance and economic cost for a power converter system. The overall system is built on master-slave structure and easy for interacting with other networks. An additional study on the cyclic redundancy check (CRC) in Modbus RTU is introduced to obtain the optimization design in the actual application and the optimization method in software design is also presented. The performance of the communication system obtained from experiment conducted on the 15kW ASD system validates the effectiveness of the proposed design method. © 2008 IEEE.

关键词： Software design

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Intelligent controller for LEDs lighting systems supplied by batteries

Intelligent controller for LEDs lighting systems supplied by...

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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Feng, Bo Zhao, Zhengming Zhang, Yingchao Zhou, Dejia Yuan, Liqiang State Key Laboratory of Control and Simulation Department of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781424418497

LED lighting system supplied by batteries is one of effective solutions to vehicle and photovoltaic lighting systems. In order to improve lighting performance and prolong the life of LEDs and batteries, this paper proposes a novel intelligent controller for LED lighting systems. Stage constant current (SCC) control strategy is proposed, which determines the optimal working current of LEDs (Iref) according to their ambient temperature and the capacity of batteries. For implementing SCC control strategy, a new control algorithm of double current loops and feedforward (DCLF) control is proposed based on Boost converter with constant current source. Both output current and inductor current are used as feedback control variables and input voltage is employed as feedforward compensation in the proposed algorithm. simulations have been conducted using PSIM software;and based on that, a 50W photovoltaic LED lighting system has been developed to implement a serial of comparative experiments. The results show the advantages and validity of DCLF algorithm, such as excellent dynamic performance and good robustness. © 2008 IEEE.

关键词： Light emitting diodes

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Design and implementation of the compact main circuit of IGBT-based converter

Design and implementation of the compact main circuit of IGB...

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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Wang, Xuesong Zhao, Zhengming Yuan, Liqiang Zhang, Yingchao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781424418497

The compact main circuit has many advantages, such as reducing volume and weight, saving costs and convenient for transportation. This paper presents three key problems including switching power supply, sampling and protection system, and cooling system. Through simplifying circuit and optimizing device parameters, the switching power supply can provide multiplex regulated power supplies with 540 VDC input directly. A simple circuit based on ripple principle can detect missing phase of input fault easily. The heat sink can be designed in a small volume through selecting suitable cooling fans, reducing switching frequency and setting minimum pulse width. A 15kW converter has been designed and implemented based on the above. Furthermore, this main circuit has been proved by practical application and long-term reliable operation. © 2008 IEEE.

关键词： Cooling systems

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