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2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011)

作者： Kui Wang Yongdong Li Zedong Zheng Lie Xu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781457705427

Modular multilevel converter (MMC) is a newly emerging multilevel topology for high power applications in recent years. The voltage fluctuation problem of a new MMC topology is studied in this paper. In order to suppress the voltage fluctuation of the floating capacitors, a control method is proposed by injecting high frequency zero-sequence voltage and phase-to-phase circulating currents. It can be used to drive an induction motor with pump/blower-like load at low speed and improve the performance significantly. A low power three-phase five-level prototype is built up to validate this method.

关键词： Bridge circuits Fluctuations Capacitors Voltage fluctuations Voltage control Frequency modulation Time frequency analysis

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Air-gap magnetic field distribution and inductance characteristics in a long primary sectional powered variable pole pitch linear induction motor

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Qinghua Daxue Xuebao/Journal of Tsinghua University 2014年第9期54卷 1161-1165and1172页

作者： Mu, Shujun Chai, Jianyun Sun, Xudong Wang, Shanming State Key Lab. of Security Control and Simulation of Power Systems and Large Scale Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China

This study investigated the air-gap magnetic field distribution and inductance characteristics of a long primary sectional powered variable pole pitch linear induction motor (VPPLIM). A one-dimensional analytical model and a 2-D finite element model were used to analyze the air-gap magnetic field distribution in the VPPLIM with harmonic fields for uniformly accelerating the mover with a typical AC supply. The air-gap magnetic field distribution was used to develop analytical expressions for the self-and mutual-inductances of the motor and their characteristics. The analytical expressions are verified by the finite element simulations. ©, 2014, Press of Tsinghua University. All right reserved.

关键词： Inductance

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Research on perception of power system state based on WAMS

Research on perception of power system state based on WAMS

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Innovative Smart Grid Technologies (ISGT)

作者： Yunfeng Cheng Chao Lu Kun Men Liang Tu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing P.R. China Academy of China Southern Power Grid Guangzhou P.R. China

ISBN: (纸本)9781479917860

The development of Smart Grid requires more accurate and fast for perception, assessment and control of power system state. Widely installed phasor measurement units (PMU) and mass PMU measurements provide a good foundation for this requirement, because PMU can directly measure bus voltage phasors at the rate of tens of milliseconds. Thus, the number of PMU installed in the power grid and the reliability and accuracy of PMU measurements are of great importance, which directly affect the feasibility and reliability of state perception. Actually, PMU measurements may contain bad data and the accuracy of phase measurements is not high enough. Estimation method is an effective way to deal with data contaminated by noise and bias. In this paper, we proposes the complex number weighted least squares (CWLS) estimation algorithm to process PMU measurements directly in the complex domain to obtain more accurate system state. Phasor error characteristics in the complex domain are analyzed depth which shows the proposed algorithm is robust to phase error. Meanwhile, an effective bad data identification method is proposed. Test results demonstrate the performance of the CWLS algorithm from the perspectives of computional efficiency, estimation quality and adaptability to inconsistent measurment errors, the robustness of the CWLS algorithm and the effectiveness of the proposed bad data identification method is also shown in the tests.

关键词： Phasor measurement units Estimation Measurement errors Voltage measurement power systems Phase measurement Algorithm design and analysis

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Space Charge Transport of $\boldsymbol{\text{Al}_2 \mathrm{O}_3}$ /Silicone Rubber Composites Under Thermal Aging

Space Charge Transport of $\boldsymbol{\text{Al}_2 \mathrm{O...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Yunxiao Zhang Chenning Yan Kai Wu Yuanxiang Zhou Tianfeng Zhang College of Electrical Engineering and Automation Fuzhou University Fuzhou Fujian China Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China Electric Power Research Institute Anhui Electric Power Company of State Grid Hefei China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407519

Silicone rubber (SIR) has been widely used in the insulation of cable accessories due to its excellent performance. In this paper, pure SIR and nano $\boldsymbol{\text{Al}_2 \mathrm{O}_3 / \text{SIR}}$ composites are thermally aged for 0–80 days at $\boldsymbol{200^{\circ} \mathrm{C}}$ . The effects of long-term thermal aging on the space charge transport are analyzed. The results show that with the increase of thermal aging time, the accumulation of heteropolar charge of pure SIR and nano $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites gradually decreases and changes to the accumulation of homopolar charge. Compared with pure SIR, the space charge accumulation of $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites decreases significantly and changes little with the increase of thermal aging time. It is believed that when doped nano $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}}$ in SIR, the increase of carrier mobility and the introduction of metal oxides reacting with fallen free radicals to form stable compounds both lead to less space charge accumulation of $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites.

关键词： Nanocomposites Impurities Metals High-voltage techniques Aging Space charge Thermal analysis

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Research on Characteristics of Surface Electric Field on Transmission Lines under Lightning Stroke

Research on Characteristics of Surface Electric Field on Tra...

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第七届亚太防雷国际会议

作者： Zhanqing Yu Zhizhao Li Qian Li Chijie Zhuang Rong Zeng Yong Zhang Yongli Liao State Key Lab of Control and Simulation of Power Systems and Generation EquipmentsDepartment of Elec Department of Mathematical Sciences Tsinghua UniversityHaidian DistrictBeijing 100084China Electric Power Research Institute CSGGuangzhou China

Lightning is a major cause of power interruptions in power transmission *** the Leader Progression Model is an advanced method to evaluate the shielding failure probability of transmission *** the surface electric field on phase conductors and ground wires precisely is important, because the surface electric field has great effect on the upward leader *** this paper, the influence of lightning current and some other factors on surface electric field were analyzed.

关键词： surface electric field transmission lines leader progression model UHVAC

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Nanosecond-pulse Dielectric Barrier Discharge Using Magnetic Compression Solid-state Pulsed power

Nanosecond-pulse Dielectric Barrier Discharge Using Magnetic...

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IEEE International power Modulator and Hogh Voltage Conference

作者： Tao Shao Yang Yu Cheng Zhang Zheng Niu Dongdong Zhang Jue Wang Yaohong Sun Ping Yan Yuanxiang Zhou Institute of Electrical Engineering Chinese Academy of Sciences State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Electrical Engineering Department Tsinghua University

ISBN: (纸本)9781424471317

Dielectric barrier discharge excitated by unipolar pulsed power is a promising approach for producing non-thermal plasma at atmospheric pressure. A magnetic compression solid-state pulse power generator is used to produce dielectric barrier discharge (DBD). The generator is capable of providing repetitive pulses with the voltage of up to 30 kV and duration of 70 ns at a 300 Ω resistive load. This paper illustrates electrical characteristic and luminous emissions of DBD excitated by repetitive unipolar nanosecond-pulses in atmospheric air. Different from common DBD excitated by high-voltage AC sources, discharge current of DBD in the experimental investigation can be on an order of tens of amperes. When the DBD is created using two liquid electrodes, the luminous emissions from the obverse and flank sides of liquid electrodes show that no filament is observed and the discharge is homogeneous and diffuse in the whole discharge regime.

关键词： Dielectric barrier discharge Pulsed power Magnetic compression Repetitive nanosecond pulses Atmospheric pressure air Gas discharge Homogeneous discharge

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Modeling and analysis of secondary controlled virtual synchronous generator with dynamic droop for microgrid

Modeling and analysis of secondary controlled virtual synchr...

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IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Weihang Yan David Wenzhong Gao Fang Zhang Lin Cheng Shijie Yan Department of Electrical and Computer Engineering University of Denver Denver USA State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China College of Information Science and Technology Northeastern University Shenyang China

ISBN: (纸本)9781538614280

In this paper, a dynamic droop mechanism is proposed to damp the synchronizing oscillation that exists in a virtual synchronous generator based distributed generator system without varying the steady-state active-power-loop droop coefficient. In order to eliminate the steady-state error introduced due to load changes or generator trips, a distributed secondary controller based on extremum seeking is employed so that microgrid frequency can be restored to nominal value. Besides, the small-signal model of virtual synchronous generator system is presented under d-q reference frame where virtual synchronous generator is deployed as a PV node. Moreover, the linearized system model of virtual synchronous generator with dynamic droop mechanism is derived and its advantage is discussed. Finally, a modified IEEE 14 bus microgrid system is established in Matlab/Simulink platform. simulation results demonstrate the validity and feasibility of the proposed method.

关键词： Mathematical model Microgrids Synchronous generators Frequency control Inverters power system stability power system dynamics

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Overvoltage Suppression Strategy Based on Active control of Current for Half-Wave Commutated Modular Multilevel Converters

Overvoltage Suppression Strategy Based on Active Control of ...

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IEEE International Conference on power and Energy systems (ICPES)

作者： Bao Liu Yunfei Xu Guoliang Zhao Nan Fu Chen Jia State Key Laboratory of Advanced Power Transmission Technology China Electric Power Research Institute Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Electric Power Research Institute of State Grid Liaoning Electric Power Co. Ltd. Shenyang China

ISBN: (数字)9798350391329

ISBN: (纸本)9798350391336

Flexible low-frequency AC transmission technology combines the advantages of 50 Hz AC transmission and DC transmission, and has good application scenarios. High voltage and large capacity AC/AC converters are the core equipment of flexible low-frequency AC transmission systems. The proposal of half-wave commutated modular multilevel converters effectively reduces the number of components and improves system economy. In view of this, this paper proposes an overvoltage suppression strategy for active control of inductor current, which effectively reduces the overvoltage level during commutation. The article first introduces the sparse topology and mathematical model of the half-wave commutated modular multilevel converters. Secondly, the mechanism of overvoltage generation is analyzed. Then, overvoltage suppression strategies are proposed. Finally, a PSCAD simulation model is built to verify the effectiveness and feasibility of the proposed method through simulation.

关键词： Multilevel converters Reactive power Bridge circuits Valves Mathematical models Topology Safety Voltage control Inductors PSCAD

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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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Review on Pumped Storage power Station in High Proportion Renewable Energy power System

Review on Pumped Storage Power Station in High Proportion Re...

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IEEE Student Conference on Electric Machines and systems

作者： Bingxin Sun Shuping Tian Jiang He Liande Liu Zhiqiang Wang Jiawei Guo Fei Xu Te Cheng Junhui Li Inner Mongolia Hohhot Pumped-Storage Power Generation Co LTD Hohhot China State Key Lab of Power Systems Tsinghua University Beijing China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education (Northeast Electric Powe University) Jilin China

ISBN: (数字)9781728156224

ISBN: (纸本)9781728156231

Large scale renewable energy, represented by wind power and photovoltaic power, has brought many problems for the safe and stable operation of power system. Firstly, this paper analyzes the main problems brought by large-scale wind power and photovoltaic power integration into the power system. Secondly, the paper introduces the basic principle and engineering construction of pumped storage power station. Thirdly, the paper expounds in detail the current application of pumped storage power station in power system, and finally points out the main problems faced by the development of Pumped Storage power Station and the development trend, so as to provide reference for the construction and operation of pumped storage power station.

关键词： Photovoltaic systems Renewable energy sources Conferences Pumps Wind power generation Market research power systems

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