检索结果-内蒙古大学图书馆

第七届亚太防雷国际会议

作者： Xiao Zhang Jinliang He State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Lightning overvoltage protection is of great importance to the safety of UHV *** widely used arresters can only suppress the magnitude of lightning overvoltage but lack efficiency on alleviating the *** practice, insulation failure of UHV transformer is often reported.A new protection method is proposed in this paper using ferromagnetic ring as supplement to arresters to suppress lightning overvoltage in UHV ***, equivalent model based on the characteristic of ferromagnetic material and factual dimension of the ring is established for *** of an actual 1000kV GIS is carried out to thoroughly evaluate the lightning overvoltage suppressing effect of ferromagnetic rings with different materials and structure dimensions.

关键词： ferromagnetic ring lightning overvoltage UHV

来源：评论

学校读者我要写书评

暂无评论

Research on surface electric field of parallel gap

Research on surface electric field of parallel gap

引用

2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Yu, Junjie Yu, Zhanqing Zeng, Rong Chen, He Peng, Xiang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China Maintenance and Test Center of EHV Power Transmission Company China Southern Power Grid Co. Ltd. Guangzhou 510663 China

ISBN: (纸本)9781457714665

With parallel gap, by controlling the motion path of the electric arc, effectively avoid burning and damaging the insulator during lightning strike so that the effect to reduce the accident rate of line is obvious. Because of simple structure, convenient installation and good economical efficiency, its importance in measures of lightning protection for transmitting line is continually improved. Electric field characteristics on the surface of parallel gap electrode have obvious influence on corona generation and the gap breakdown position and are the key parameters that must be considered in the design. Based on the finite element method, this paper sets up the analysis model of electric field of parallel gap including the tower, the conductor and the insulator, uses ANSOFT software for simulation, studies the surface electric field characteristics of parallel gap electrode, compares the electric field of four types of parallel gap put forward in the paper and analyzes the law of influence of parallel gap electrode parameters on the electric field characteristics. The results show that, when the short circuit distance is increased, the maximum values of electric field of ball end and snap ring body are obviously increased;the opening angle of snap ring is larger and the maximum value of electric field of ball end is higher;when the pipe diameter is increased, the maximum value of electric field of snap ring body is reduced considerably;the ball end is bigger and the maximum value of electric field of ball end is less;the ring pipe diameter is the structure parameter having the largest influence on the surface electric field;for the ball end at the end of ring electrode, the structure parameter having the largest influence on the electric field is the diameter of ball end. Reducing the distance that the ball end stands out of the ring plane can decrease the maximum value of electric field of ball end. © 2011 IEEE.

关键词： Finite element method

来源：评论

学校读者我要写书评

暂无评论

Research on impulse discharge characteristics of parallel gap

Research on impulse discharge characteristics of parallel ga...

引用

2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Chen, He Peng, Xiang Yu, Zhanqing Yu, Junjie Zeng, Rong Maintenance and Test Center of EHV Power Transmission Company China Southern Power Grid Co. Ltd. Guangzhou 510663 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457714665

With parallel gap, by controlling the motion path of the electric arc, effectively avoid burning and damaging the insulator during lightning strike so that its importance in measures of lightning protection for transmitting line is continually improved. Initial discharge position is key consideration during design of parallel gap and depends on discharge characteristics of parallel gap under the action of lightning surge when the lightning strikes the tower or line. This paper gives three types of parallel gap used to protect the composite insulator, sets up the impulse discharge test and observation platform including high-speed camera, studies the impulse discharge characteristics of parallel gap and analyzes the influence of structural parameters on the discharge characteristics. This study showed that there is randomness for discharge path of parallel gap;three types of parallel gap given in this paper can achieve 100% discharge rate of parallel gap;the determinant of discharge rate in the presupposition discharge area (PDA) is the distance that the presupposition discharge area stands out of the whole electrode plane. When this distance exceeds 20mm or more, it can ensure that most of the discharge occurs in the PDA;the parallel gap can reduce the insulation distance of 4000mm insulator about 40mm, U50 about 1%, which may approximately consider that the parallel gap has no influence on the insulating property of the insulator. © 2011 IEEE.

关键词： Electric arcs

来源：评论

学校读者我要写书评

暂无评论

Modeling and analysis of MW-level grid-connected PV plant

Modeling and analysis of MW-level grid-connected PV plant

引用

Annual Conference of Industrial Electronics Society

作者： Yi Lei Zhengming Zhao Wei Xu Jianguo Zhu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China School of Electrical Mechanical and Mechatronic Systems University of Technology Sydney Australia

This paper focuses on the modeling and analysis of the basic composition, characteristic and the interactions with grid for megawatt (MW)-level large scale grid-connected photovoltaic (PV) plants. For a MW-level PV plant, numbers of inverters with relatively smaller capacity are employed to operated in parallel. When the irradiance on the large area of PV array is not equal, the output power verses the voltage of the PV array will have several peak values and affect the maximal power tracking. LCL filters are adopted for filtering the harmonics generated by inverters, but due to its inherent resonance character, additional damping strategy is required. The power quantity of harmonics and voltage fluctuation may occur when one MW-level PV plant is connected to grid. For these characteristics, with the modeling and simulation of a real MW-level PV plant, this paper proposed and verified a novel method toward MPPT of large area PV arrays. The parallel running of inverters and grid voltage fluctuation are also simulated. Finally, the interaction with the grid voltage fluctuation is explored in detail.

关键词： Inverters Arrays Photovoltaic systems Fluctuations Voltage fluctuations

来源：评论

学校读者我要写书评

暂无评论

A DC-link Voltage control Scheme for Single-phase Grid-connected PV Inverters

A DC-link Voltage Control Scheme for Single-phase Grid-conne...

引用

2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011)

作者： Fanbo He Zhengming Zhao Liqiang Yuan Sizhao Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781457705427;9781457705410

A fast DC-link voltage controller is desirable to reduce the DC-link capacitor for PV inverters. This paper proposes a method for single-phase grid-connected PV inverters to remove the ripple component from the DC-link voltage signal and a scheme to regulate the DC-link voltage based on energy-balance analysis. The proposed scheme provides excellent dynamic performance as well as a function to prevent DC-link overvoltage by limiting the input power, which is verified by both simulation and experiments.

关键词： DC link Polydnaviridae dc-link capacitor Inventors Voltage regulators dynamic characteristics DC link voltage Scheme Voltage regulation link voltage

来源：评论

学校读者我要写书评

暂无评论

A self-healing reconfiguration technique for smart distribution networks with DGs

A self-healing reconfiguration technique for smart distribut...

引用

International Conference on Electrical and control Engineering (ICECE)

作者： Dapeng Li Shouxiang Wang Jie Zhan Yishu Zhao Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China State grid of china technology College Jinan Shandong China

The requirement for power supply reliability and power quality has been increasing. When a fault occurs in distribution networks, fast locating and isolating the fault, restoring the power, and reducing outage time and area are becoming more and more crucial. The concept of fast self-healing has been proposed, which is also the requirement for smart grid development. In this paper, a self-healing reconfiguration technique is proposed for smart distribution networks with insertion of distributed generations (DGs). And a tree structure algorithm based on heuristic rules is proposed. Islands formed by DGs are used to deal with fault isolation and power restoration after a fault occurs. The effectiveness of the proposed algorithm is verified using a 26 bus bars test system with DGs.

关键词： Reliability power system reliability Load flow Distributed power generation power quality

来源：评论

学校读者我要写书评

暂无评论

Transient interaction of HVAC and HVDC in converter station in HVDC, II: Equivalence circuit in AC side and steady-state debugging

引用

Gaodianya Jishu/High Voltage Engineering 2011年第3期37卷 537-547页

作者： Chen, Shui-Ming Huang, Lu-Lu Xie, Hai-Bin Yu, Zhan-Qing State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

The interaction of nanoseconds, microseconds, milliseconds electromagnetic transients due to AC-DC system operation and fault, the DC converter valve movement, the load generated by changes in the interaction of AC-DC interconnected system electromagnetic transient, can pose a hazard on AC and DC power systems, in particular, lead to the commutation of DC system failures and artesian such serious incidents. Combining theoretical analysis with test, we can establish the analysis method of electromagnetic transient of the full-wave process of the UHV system based on AC-DC interconnected system, control systems, and underground grounding system, and focus on the equivalence circuit of AC side network with the Ward method of equivalency under many operation modes and steady-state debugging for the analysis of AC-DC interconnected system, so as to lay the foundation for the interaction of electromagnetic transient.

关键词： Timing circuits

来源：评论

学校读者我要写书评

暂无评论

A multi-class pattern recognition method for motor imagery EEG data

A multi-class pattern recognition method for motor imagery E...

引用

2011 IEEE International Conference on systems, Man, and Cybernetics, SMC 2011

作者： Fang, Yonghui Chen, Minyou Harrison, Robert F. State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing China Department of Automatic Control and Systems Engineering University of Sheffield Sheffield S1 3JD United Kingdom School of Electronic and Information Engineering Southwest University Chongqing China

ISBN: (纸本)9781457706523

The Common Spatial Patterns (CSP) algorithm is useful for calculating spatial filters for detecting event-related desynchronization (ERD) for use in ERD-based brain-computer interfaces (BCIs). However, basic CSP is a supervised algorithm suited only to two-class discrimination;it is unable to solve multiclass discrimination problems. This paper proposes a new method named the binary common spatial patterns (BCSP) algorithm to extend the basic CSP method to multi-class recognition. Our method arranges the spatial filters and Fisher classifiers in the form of a binary tree whereby N - 1 spatial filters and N - 1 Fisher classifiers are calculated for N class recognition. This is fewer than must be calculated in other methods (e.g. one-versus-rest, OVR). This makes the overall classification procedure less redundant. simulation results show that BCSP has better performance than the OVR scheme and outperforms the three best teams in the 2008 BCI-competition. © 2011 IEEE.

关键词： Brain computer interface

来源：评论

学校读者我要写书评

暂无评论

Effect of Different Arresters on Switching Overvoltages in UHV Transmission Lines

引用

Tsinghua Science and Technology 2010年第3期15卷 325-328页

作者：杨鹏程陈水明何金良 State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress switching overvoltages in UHV transmission lines. Switching overvoltages on the 1000 kV Huainan-Huxi double-circuit transmission line were simulated for different operating modes and different arrester designs using the electromagnetic transient program PSCAD/EMTDC. With parallel resistors, the switching overvoltages are less than 1.70 p.u. （1.0 p.u.=1100×√ 2 /√3 kV）. If the arrestors are better, the switching overvoltages can be reduced even lower to 1.55 p.u. Without parallel resistors, the arresters can reduce three-phase energizing overvoltages to 1.70 p.u, while the single-phase reclosing overvoltages still exceed the limit. The results show that the parallel resistors cannot be eliminated if the arresters are only installed at each end of the transmission line. Also, better quality arresters significantly lower the switching overvoltages.

关键词： UHV double-circuit transmission line switching overvoltages arresters

来源：评论

学校读者我要写书评

暂无评论

Voltage Fluctuation Suppression Method of Floating Capacitors in a New Modular Multilevel Converter

Voltage Fluctuation Suppression Method of Floating Capacitor...

引用

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

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：