检索结果-内蒙古大学图书馆

World Non-Grid-Connected Wind power and Energy Conference, WNWEC

作者： Jie Chen Dongxiang Jiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing China

As the support structure of wind turbine, the tower bears alternating loads of wind when the wind turbine runs. To ensure the reliability of the wind turbine, it's necessary to carry out modal analysis on the tower, and this would prevent the natural frequency of the tower close to the rated speed of wind turbine. In this paper, finite element analysis of the tower is solved using ANSYS, and the natural frequencies and modes of the tower are presented. After comparing the results of three models, a simple model for modal analysis, which can be calculated in short time, is finally determined.

关键词： Poles and towers Wind turbines Modal analysis Finite element methods Analytical models Material properties Solid modeling

来源：评论

学校读者我要写书评

暂无评论

Predictive DC voltage control for three-phase grid-connected PV inverters based on energy balance modeling

Predictive DC voltage control for three-phase grid-connected...

引用

IEEE International Symposium on power Electronics for Distributed Generation systems (PEDG)

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

DC voltage control is critical for grid-connected inverters, as it contributes to reduce the DC capacitance and improve system reliability as well as MPPT performance. A predictive control scheme of DC voltage for single-stage three-phase grid-connected PV inverters is proposed based on the analysis of the energy balance relationship in one control period, while AC current is also regulated by predictive control. The proposed scheme provides both good dynamic and steady-state performance. The dynamic response is especially excellent. The DC voltage is adjusted as fast as possible with little overshoot.

关键词： Voltage control Inverters Voltage measurement Regulators Predictive control Steady-state Capacitance

来源：评论

学校读者我要写书评

暂无评论

Current sharing of IGBT modules in parallel with thermal imbalance

Current sharing of IGBT modules in parallel with thermal imb...

引用

IEEE Energy Conversion Congress and Exposition, ECCE

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

For large current, switching devices such as MOSFET and IGBT, often have to be connected in parallel. Due to this reason, derating and preselection of the switching devices become necessary to develop high-power converters. The current imbalance can be produced by stray inductances, device characteristic difference or asymmetric circuit. Moreover, thermal imbalance is another important reason for current balancing. The static and transient characteristics of an IGBT vary sensitively with its junction temperature. This paper focuses on the current sharing of IGBTs in parallel with thermal imbalance. In this paper, an active gate control method which can achieve current balancing of the IGBTs in parallel with thermal imbalance, is explained and verified by experiments. This method can be applied to an actual 160kW/380V power electronics converter prototype for improving the utilization of the switching devices and enhancing system reliability.

关键词： Insulated gate bipolar transistors Junctions Temperature measurement Temperature Temperature control Logic gates Transient analysis

来源：评论

学校读者我要写书评

暂无评论

Application of back propagation neural network to fault diagnosis of direct-drive wind turbine

Application of back propagation neural network to fault diag...

引用

World Non-Grid-Connected Wind power and Energy Conference, WNWEC

作者： Xueli An Dongxiang Jiang Shaohua Li State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing China

The vibration signals of wind turbines are highly nonlinear and non-stationary due to wind turbine operation conditions that are very complicated. The signals will be more complex when a fault occurs. Aiming at these problems, a fault diagnosis method for direct-drive wind turbine is presented based on back propagation neural network (BPNN). The time-domain feature parameters of vibration signals in the horizontal and vertical direction are considered in the method. Five experiments of direct-drive wind turbine with normal, wind wheel mass imbalance, wind wheel aerodynamic imbalance, yaw and blade break are carried out in laboratory scale. Through analyzing the features of five conditions, the time-domain feature parameters in horizontal and vertical direction of the vibration signal are selected as the input samples of BPNN. By training, the BPNN model can be constructed between feature parameters and fault types. The validity of the BPNN model is verified using test samples. The results indicate that the proposed method has higher diagnostic accuracy. It can used in on-line fault diagnosis of direct-drive wind turbines.

关键词： Wind turbines Vibrations Fault diagnosis Artificial neural networks Blades Wheels Time domain analysis

来源：评论

学校读者我要写书评

暂无评论

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

Basic principles of hybrid excitation PM synchronous generat...

引用

2010 International Conference on Electrical Machines and systems, ICEMS2010

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

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： Windings Harmonic analysis Stator windings Rotors Reactive power power system harmonics

来源：评论

学校读者我要写书评

暂无评论

Protection of microgrid

Protection of microgrid

引用

10th IET International Conference on Developments in power system Protection (DPSP 2010). Managing the Change

作者： Shenxing. Shi Bo. Jiang Xinzhou. Dong Zhiqian. Bo State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University China AREVA T and D Inc. Stafford UK

The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without the need of communication, uses current traveling waves to identify faulted feeder, and the bus bar voltages to determine a event caused by fault or switch operation. In the protection scheme, current traveling waves are measured by current transducers in N line and phase lines, and wavelet multi-resolution analysis is used to decompose traveling wave signals. The initial traveling waves are compared in magnitude and polarity with each other to determine the faulted feeder. The protection is independent of microgrid operation connected with the main power grid or in island.

关键词：

来源：评论

学校读者我要写书评

暂无评论

A Pi-based control scheme for primary cascaded H-bridge rectifier in transformerless traction converters

A Pi-based control scheme for primary cascaded H-bridge rect...

引用

International Conference on Electrical Machines and systems (ICEMS)

作者： Tao Xinghua Li Yongdong Sun Min Department of Electrical Engineering Naval University of Engineering China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University China

Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue in CHBR. To satisfy the demand of rectifier such as unity power factor and regulated output DC voltages, the proposed control scheme consists of two parts. One is for shaping the grid current waveform and regulating the sum of DC-link voltages of all the cells; the other one is for balancing DC-link voltages. The latter is more concerned in this paper and is discussed in detail especially. simulations and experiments are carried on. The results verified the feasibility and effectiveness of the proposed scheme.

关键词： Rectifiers Voltage control Voltage measurement Converters Pulse width modulation Mathematical model

来源：评论

学校读者我要写书评

暂无评论

state of the art of hybrid excitation permanent magnet synchronous machines

State of the art of hybrid excitation permanent magnet synch...

引用

作者： Wang, Shanming Xia, Yonghong Wang, Xiangheng Su, Pengsheng Huang, Shaogang Zhang, Anming 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 Military Deputy Department Dalian 426 Factory No.1 Yanhai Jie Xigang Qu Dalian Liaoning 116005 China

ISBN: (纸本)9788986510119

The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of regulating the excitation field. By now many HEPMM schemes have been presented. In this paper the operation principle, structure, advantages and disadvantages of these HEPMMs have been reviewed and compared in detail. These HEPMMs are classified into three types by new classification method - placement of PM and iron poles. At last novel harmonic excitation HEPMM is proposed and discussed.

关键词： Permanent magnets

来源：评论

学校读者我要写书评

暂无评论

state of the art of hybrid excitation permanent magnet synchronous machines

State of the art of hybrid excitation permanent magnet synch...

引用

2010 International Conference on Electrical Machines and systems, ICEMS2010

关键词： Iron Magnetic fields Windings Stator cores Rotors Stator windings Magnetic circuits

来源：评论

学校读者我要写书评

暂无评论

Analysis of cutting-edge techniques in the high voltage and high power adjustable speed drive systems

引用

Science China(Technological Sciences) 2009年第2期52卷 442-449页

作者： ZHAO ZhengMing BAI Hua YUAN LiQiang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

The high voltage and high power adjustable speed drive (ASD) system is one of the most attractive fields in power electronics, and it is also a very crucial technique for energy saving and emission reduction. This paper discussed and analyzed the main cutting-edge knowledge and issues in the process of exploiting the high voltage and high power ASD system.

关键词： high voltage and high power inverter safe operation area pulse and pulse sequence

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：