检索结果-内蒙古大学图书馆

Analysis of synchronous generator electro-magnetic torque and vibration with armature winding fault

Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology 2009年第4期42卷 322-326页

作者： Fang, Hong-Wei Xia, Chang-Liang Li, Guo-Ping Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin 300072 China Beijing Chatone Computer Room Equipment Company Beijing 100101 China

The air-gap magnetic field characteristic of the synchronous generator, caused by stator winding inter-turn short circuit fault, was analyzed in this paper with a consideration of the air-gap eccentricity. Then the characteristics of electro-magnetic torque and vibration of generator were obtained, especially the magnitudes and frequency variation of the instantaneous pulse torque. And the characteristic of the 17th and 19th order component of terminal current under this condition was also analyzed by the coupled field-circuit method. Lastly, in the dynamic simulation experiment, the vibration acceleration data in the vertical direction of a 7.5 kVA generator with stator winding inter-turn short circuit fault were acquired, and then these data were analyzed by discrete fast Fourier technique. The results show that the change of the double frequency vibration acceleration is bigger when stator winding inter-turn short circuit faults occur and the 17th and 19th order component of terminal current can be used to detect the dynamic eccentricity of machines with or without internal faults.

关键词： Stators

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Modeling of Busbars in High power Neutral Point Clamped Three-Level Inverters

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Tsinghua Science and Technology 2008年第1期13卷 91-97页

作者：易荣赵争鸣钟玉林 State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua University

The busbars in high power neutral point clamped three-level inverters are modeled using the Maxwell Q3D Extractor software, which is based on the partial element equivalent circuits method. The equivalent circuits of the busbars and devices model are simulated in the electric simulator PSlM to analyze the effects of the parasitic inductance on the switching characteristics of the integrated gate commutated thyristor （IGCT） in different topology positions. The simulation results agree well with the measured impedance analyzer results and the IGCT test results, which proves the effectiveness of the modeling method for the large, complex busbars.

关键词： busbars parasitic inductance partial element equivalent circuits switching characteristics

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Instantaneous energy balancing in three-level neutral point clamped converters

Instantaneous energy balancing in three-level neutral point ...

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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Ting, Lu Zhengming, Zhao Liqiang, Yuan Shuping, Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781424418497

Instantaneous energy balancing plays an important role in power electronics conversion. The unbalance of electromagnetic energy not only debases the system performance but also decreases the reliability and efficiency of the conversion. In this paper, instantaneous energy balancing problems in three-level neutral point clamped (NPC) converters are classified and discussed. Typical examples and their usual solutions of each kind of problems are expounded and compared. In the end of this paper, limitations and disadvantages of traditional methods are analyzed, and electromagnetic field method is summarized as the new trend to analyze electromagnetic energy transmission and exchange. The method using electromagnetic field theory is emphasized to be the better approach to solve the aforementioned energy balancing problems. © 2008 IEEE.

关键词： Electromagnetic waves

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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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A systematic and qualitative assessment method and software design for energy efficiency of typical electric machine systems with pumps and fans

A systematic and qualitative assessment method and software ...

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11th International Conference on Electrical Machines and systems, ICEMS 2008

作者： Yi, Lei Zhengming, Zhao Jing, Xue 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)9787506292214

Three-phase induction motors as well as power converters are intrinsically efficient machines and devices. However, due to the common misapplication of them with loads like pumps and fans, these electric machine systems are considered a great potential of energy conservation in industries. As to assessing methods of energy conservation, neither the study of induction machine efficiency nor the analysis of pumps and fans performance is new. However, the systematic and qualitative analysis and assessment of the energy efficiency of induction machines, loads and control devices acting as a whole system are still complicated yet indispensable for electric machine system energy conservation program in China. In this paper, a systematic and qualitative assessment method for energy application efficiency of electric machine system is raised. Based on this method, an assessing computer program is designed to provide referencing information for making investment decisions regarding energy efficiency measures at manufacturing plants. An expert system is also designed to choose equipments that match each other.

关键词： Investments

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DC/DC Converter Applied in the Photovoltaic- Inclined Thermal Collector Hybrid systems for Brackish Water Desalination

DC/DC Converter Applied in the Photovoltaic- Inclined Therma...

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11th International Conference on Electrical Machines and systems(第11届国际电机与系统会议)

作者： Liqiang Yuan Mohamed Eltawil Zhengming Zhao Yaodong Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department o State Key Laboratory of Control and Simulation of Power System and Generation EquipmentDepartment of

A chronic drinking water shortage is one of the most important issues in the developing countries, and drinking water from dirty water sources causes serious damage to inhabitants health in some remote areas. The solar distillation remains the most favorable process for the supplying of water to small communities. Base on the traditional solar still, an improved hybrid photovoltaic/thermal (PVT) desalination system is presented. The PV modules that are combined with thermal units, constitute the PVT systems which has longer operating time and higher average fresh water production. This paper introduces the DC/DC converter applied in this type of systems, including its structure and control strategy which is suitable for PV array and driving supportive heater. The experimental results for the converter and the whole system are showed and analyzed.

关键词： DC-DC power converters Photovoltaic systems Solar power generation Desalination Temperature Water resources Hybrid power systems Solar energy Water heating power system simulation

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A Novel Direct power control Strategy for Three-Level PWM Rectifier Based on Fized Synthesizing Vectors

A Novel Direct Power Control Strategy for Three-Level PWM Re...

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11th International Conference on Electrical Machines and systems(第11届国际电机与系统会议)

作者： Ting Lu Yongchang Zhang Yingchao Zhang Zhengming Zhao Liqiang Yuan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department o State Key Laboratory of Control and Simulation of Power System and Generation EquipmentDepartment of

A novel direct power control (DPC) strategy for three-level neutral-point-clamped (NPC) pulse-width-modulation (PWM) rectifier, based on fixed synthesizing vectors, is proposed in this paper. The strategy breaks through the restrictions of vector switching with a simple switching table, improves the excellent dynamic performance of DPC, avoids the neutral-point voltage unbalance and the excessive voltage jumps in phase and line-to-line voltages of the rectifier, and guarantees the proper minimum pulse width and switching intervals between switches in different phases simultaneously. Experimental results verify the validity and feasibility of the proposed scheme.

关键词： Pulse width modulation power control Rectifiers Space vector pulse width modulation Switches Thyristors Topology Voltage control Snubbers control system synthesis

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Instantaneous energy balancing in three-level neutral point clamped converters

Instantaneous energy balancing in three-level neutral point ...

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IEEE Conference on Vehicle power and Propulsion (VPPC)

作者： Lu Ting Zhengming Zhao Liqiang Yuan Shuping Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China. State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

关键词： Voltage control Capacitors Open loop systems Pulse width modulation converters power electronics Energy storage Switching converters power system simulation power system reliability Electromagnetic analysis

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