检索结果-内蒙古大学图书馆

2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Yin, Lu Zhao, Zhengming Lu, Ting He, Fanbo Yuan, Liqiang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457710445

This paper presents a predictive control scheme of DC-link voltage for back-to-back converters based on energy balance modeling. Since the variation of DC-link voltage is affected by the energy mismatch between rectifier and inverter, the energy distribution in a rectifier-inverter is analyzed. Moreover, in order to calculate the input and output energy in one control period accurately, the grid current is regulated by predictive control and the instantaneous active power consumed by the induction motor is estimated. Then, an equation based on energy balance in one control period is established, and the DC-link voltage can be controlled by solving it. Finally, simulation results show that with the proposed control scheme, the back-to-back converter exhibits both good dynamic and steady-state performances. © 2011 IEEE.

关键词： Energy balance

来源：评论

学校读者我要写书评

暂无评论

Optimal design of the back-to-back IGBT-based converter with the concept of systematic safe operating area

Optimal design of the back-to-back IGBT-based converter with...

引用

2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Zou, Gaoyu Zhao, Zhengming Yuan, Liqiang Wang, Xuesong Lu, Ting State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457710445

The key parameters of SOA (safe operating area) of semiconductor devices are hard to be measured when converter is operating, which is not helpful to protect converter at any time. On the other hand, surplus estimating method is widely used to design the main circuit. In order to guarantee the whole system works safely and improve utilization rate of devices, the concept of SSOA (systematic safe operating area) is presented. By determining the relationship of key parameters between devices and converter, the expression of SSOA is described quantitatively. Then it is implemented as a basic rule to design a back-to-back converter based on IGBT for 55kW induction motor optimally. Rated value of DC-link voltage and grid filter of the system is obtained reasonably as well. © 2011 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

来源：评论

学校读者我要写书评

暂无评论

Design, simulation and analysis of the low stray inductance bus bar for voltage source inverters

Design, simulation and analysis of the low stray inductance ...

引用

2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Yuan, Liqiang Yu, Hualong Wang, Xuesong Zhao, Zhengming State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457710445

Hard-switching technique under the high voltage and high current is one of main trends of high power inverters. Under this switching mode, the stray parameters of the commutating loops, especially the stray inductance of the DC bus bar, have significant influence on the switching process, electromagnetic interference and component stress of the semiconductor switches. It becomes one of the key points for the safe operation of inverters. Based on an actual 55kW inverter, the design, simulation and analysis for its bus bar is described in this paper. The bus bar model is built with the method of Partial Element Equivalent Circuit (PEEC), and the stray parameters are extracted from PEEC model and applied in the circuit simulation. Compared with the experimental results, the modeling validity is proved, and the simplified modeling process and design principles for complex physical bus bar are presented. © 2011 IEEE.

关键词： Circuit simulation

来源：评论

学校读者我要写书评

暂无评论

Dimensionality reduction analysis in condition classification of prognostics

Dimensionality reduction analysis in condition classificatio...

引用

Applied systems Health Management Conference 2011: Enabling Sustainable systems, MFPT 2011

作者： Liu, Chao Jiang, Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 China

In order to maintain the separability of different fault onsets, more characteristic parameters need to be used to establish the feature space with multiple possible faults. Usually, the dimensions of feature space have a positive correlation with the number of faults. Describing multiple faults in visualization is more difficult and the classification bounds with hyperplanes are less convenient to realize. Therefore implementing dimensionality reduction approaches in original feature space is beneficial for fault diagnosis and prognostics. Multidimensional Scaling (MDS) has been widely studied and used for dimensionality reduction as well as Principal Component Analysis (PCA). When these methods are applied in the prognostics process, the effectiveness needs validation with the reason that the deterioration features in degradations are different from the faults onsets that in diagnostics. The paper analyzes the nonlinear dimensionality reduction methods including Self-Organizing Map (SOM) and Isometric feature mapping (Isomap). Based on the deterioration data in an engine, the effects of these methods are analyzed.

关键词： Self organizing maps

来源：评论

学校读者我要写书评

暂无评论

Lightning overvoltage suppression of power transformer in UHV GIS by ferromagnetic ring

Lightning overvoltage suppression of power transformer in UH...

引用

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

作者： Zhang, Xiao He, Jinliang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457714665

Lightning overvoltage protection is of great importance to the safety of UHV GIS. The widely used arresters can only suppress the magnitude of lightning overvoltage but lack efficiency on alleviating the steepness. In 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 GIS. Moreover, equivalent model based on the characteristic of ferromagnetic material and factual dimension of the ring is established for calculation. simulation 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. © 2011 IEEE.

关键词： power transformers

来源：评论

学校读者我要写书评

暂无评论

Machine condition classification using deterioration feature extraction and anomaly determination

Machine condition classification using deterioration feature...

引用

作者： Jiang, Dongxiang Liu, Chao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

Condition classification has been widely used for assessing equipment status for machine condition monitoring and diagnostics. An engine was fitted with one temperature and two pressure sensors to study the machine conditions in prognostics with an added abnormal state, in addition to the conventional normal and failure states. This work enables a better classification capability in order to predict deterioration in the engine. Information related to three deterioration processes was collected, and preprocessed using singular point elimination, deviation value acquisition, and data normalization. Wavelet transforms were used to extract deterioration features with different mother wavelets. The mother wavelets were selected using t tests to optimize the wavelet selection. The deterioration was related to the amount of anomaly, with the abnormal states defined to distinguish the functional from the failure states. A Learning Vector Quantization (LVQ) neural network was used to classify the machine conditions, including normal, abnormal, and failure states. The results showed that the deterioration features defined using the Daubechies wavelet (db8) most strongly correlated with the original signal, so that the classification accuracy based on the deterioration features was greatly improved. The LVQ classification system had good accuracy for machine condition classification, and was adaptable to various engine conditions. © 2010 IEEE.

关键词： Deterioration

来源：评论

学校读者我要写书评

暂无评论

Improved Blade Tip Timing in Blade Vibration Monitoring with Torsional Vibration of the Rotor

引用

Journal of Physics: Conference Series 2012年第1期364卷

作者： Chao Liu Dongxiang Jiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 People's Republic of China

Due to the complex conditions in rotating machinery, the blades usually encounter fluctuating loads, and failures may occur in the operation. Blade vibration is rarely monitored in the practical rotating machinery in power plants as the traditional blade vibration method using strain gauge method is hard to be applied in long-time and online monitoring. The blade tip timing method is a promising approach to monitor the blade vibration and several special sensors are developed to realize the online monitoring. Based on the traditional blade tip timing method, an improved approach is established in this work. The proposed method can modify the expected arriving time when the torsional vibration exists. The accuracy is therefore improved in the torsional vibration case. Then the blade vibration monitoring with the traditional blade tip timing method and the proposed method are carried out in the test rig in laboratory. The results validate that, the torsional vibration influences the expected arriving time, and the proposed method can modify the expected arriving time and improve the accuracy of the blade vibration monitoring.

关键词：

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

2nd Annual Conference on Electrical and control Engineering, ICECE 2011

作者： Li, Dapeng Wang, Shouxiang Zhan, Jie Zhao, Yishu Key Laboratory of Power System Simulation and Control Tianjin University Ministry of Education Tianjin 300072 China State Grid of China Technology College Shandong Jinan 250002 China

ISBN: (纸本)9781424481637

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. © 2011 IEEE.

关键词： Distributed power generation

来源：评论

学校读者我要写书评

暂无评论

Mathematical models of the system-level safe operational areas of power electronic converters in plug-in hybrid electric vehicles

Mathematical models of the system-level safe operational are...

引用

作者： Wang, Xuesong Bai, Hua Zhao, Zhengming Yuan, Liqiang China Power Engineering Consulting Group Corporation Beijing 100011 China Kettering University Flint MI 48504 United States State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China

With the development of plug-in hybrid electric vehicles (PHEVs), power electronics plays an increasingly important role in electric power train systems. The economic and reliable design of these power electronic systems, e.g., dc/ac inverter and battery charger, will be the inward search to popularize electric vehicles. As an extension of system-level safe operational areas (SSOAs) proposed in our previous literature, this paper details the criteria and mathematical models of SSOA for a battery charger and a three-phase two-level dc/ac inverter. Operational areas were established based on the SSOA. Thermal characteristics of the semiconductor devices, operational modes, and load characteristics were enclosed to enhance the mathematical models. Experiments on a 5-kW charger and a 55-kW/380-VAC inverter validated the effectiveness of SSOA. © 2011 IEEE.

关键词： Metals

来源：评论

学校读者我要写书评

暂无评论

A neutral-point potential balancing algorithm for five-level ANPC converters

A neutral-point potential balancing algorithm for five-level...

引用

International Conference on Electrical Machines and systems (ICEMS)

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

Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point clamped (NPC) converters and flying-capacitor (FC) converters. Its dc-link is subdivided into two equal parts and the main problem is the neutral-point (NP) potential balancing. In this paper, a NP potential balancing algorithm based on zero-sequence voltage injection is presented. By calculating the NP currents of all key zero-sequence voltages, the most appropriate zero-sequence voltage is selected to generate the demanded NP current. Moreover, by further limiting the span of injected zero-sequence voltages, the NP balancing algorithm can make the two IGBTs connected in series operate at fundamental frequency. A three-phase five-level ANPC inverter prototype was built up and experimental results are presented to verify the validity of this algorithm.

关键词： Capacitors Electric potential Switches Voltage control Inverters Insulated gate bipolar transistors Heuristic algorithms

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：