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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

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Gas generation Characteristics of Transformer oil under Combined AC-DC Voltages in the Process of Arcing

Gas Generation Characteristics of Transformer oil under Comb...

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Annual Report Conference on Electrical Insulation and Dielectric Phenomena

作者： Y.X. Zhou Y.C. Sha X.X. Jiang Q.H. Sun Y.S. Wang J.H. Tian State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing China

ISBN: (纸本)9781457709852

As an important equipment, convertor transformer plays a crucial role in ultra high voltage direct current (UHVDC). How to improve the safety running level of convertor transformers is a key problem to be solved imminently. Compared with AC power transformers, the valve side windings of convertor transformers will endure combined AC-DC voltage. In these conditions, the gas generation characteristics in oil for convertor transformers will be more complicated. In this paper, according to the operational principle of convertor transformers, the ratios between AC and DC voltage on valve side windings in the star connection and triangular connection were 77.1% and 83.7% respectively. Based on the above results, 65 kV peak voltages in 5 different AC and DC voltage forms were applied to the needle-plate electrode model for 2 hours. The discharge current and voltage waveforms were recorded and the arc current pulses had a short lasting time about 1.2 ms. Then the mean discharge energy was calculated at 0.1 to 0.3 J. At the same time, the gas generation characteristics under combined AC-DC voltage were obtained by using the gas chromatographic analysis method. The variations of amounts and generation rates of characteristic gases were measured with time during 2 hours, which provided fault judgment criterions and experimental experience. The experimental results showed that the amounts and generation rates of H2, C2H2 and total hydrocarbon under the pure DC voltage or combined AC-DC voltage were more than those under the pure AC voltage. It might illustrate the fact that effects of different voltage forms would lead to different gas generation characteristics could not be ignored.

关键词： Combined AC-DC voltage Needle-plate electrode model Gas generation Characteristics

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Research of protection communication system in process level of intelligent substation

Research of protection communication system in process level...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Fei Xu Bin Wang Xinzhou Dong Runbin Cao Kun Liu Yuelin Yang Tingting Wu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China College of information and electrical engineering China Agricultural University college of information and electrical engineering China Agricultural University School of Electrical Engineering & Renewable Energy China Three Gorges University Yichang China

The paper mainly focuses on the communication problem based on IEC61850 communication protocol. As in the process level communication system: MU (Merging Unit)-Switch-DIPC (Digital Integrated Protection and control system), the stability of SMV packets transmission is very important. The transmission delay of the process level communication is the key problem that may restrict the protection algorithm and capability. In the meantime, GPS synchronization problem of MUs, protection capability of the integrated protection device and stability of SMV message transmission based on the existing DIPC(DIP-01) system will also be discussed in the paper. Through the experiment and analysis, the paper gives out the key factors that lead to the message transmission delay and packets loss. The work at last gives out some primary ideas to improve the protection capability.

关键词： Random access memory Switches Synchronization Optical fiber devices Delay

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Designation and development of hardware platform for intelligent ter-minal in 126kV Smart substation

Designation and development of hardware platform for intelli...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Tong Sun Bin Wang XinZhou Dong ShuJian Zhang MingCai Kang RunBin Cao School of Automation Nanjing University of Science and Technology Jiangsu 210094 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Electrical engineering and automation Hefei University of Technology Anhui 230009 China

According to the demand of 126kV intelligent switch with intelligent operative box, an intelligent terminal device by using cooperation control of embedded CPU (STM32F103ZET6 ARM) and Field Programmable Gates (Cyclone II EP2C8Q208C8 FPGA), which is up to the IEC61850 standard, is designed in this paper. Research program of the device is discussed. Starting from the modularization structure design, function of each module, circuit design and implementation method were introduced in detail. A hardware platform was established according to the design. Finally, the article confirmed the correctness of the hardware platform primarily through experimental method.

关键词： Optical fiber LAN Voltage measurement Measurement units Optical fibers Switchgear Field programmable gate arrays Sun

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IEC61850-based information modeling of 126KV intelligent terminals

IEC61850-based information modeling of 126KV intelligent ter...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Shu-jian Zhang Bin Wang Ming Sun Xin-zhou Dong Tong Sun Run-bin Cao Electrical engineering and automation Hefei University of Technology Baohe District 230009 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China School of Automation Nanjing University of Science and Technology Jiangsu 210094 China

The stability and reliability of the intelligent terminal's receiving information affects its control of intelligent switch in operation directly. To achieve reliable intelligent communications terminals, with techniques and methods of IEC61850 modeling, the paper completed the 126KVGIS intelligent terminal information model based on the analysis of its information characteristics, and established the hardware platform with data model and logical nodes provided by IEC61850. Thus it has a certain practical significance to promote the standard construction, operation and management of intelligent substation, and lead the digital process of process layer devices.

关键词： Object oriented modeling Switching circuits Circuit breakers Data models Unified modeling language Analytical models

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Demand analysis of the information sharing among multi-bays through the process networks in intelligent distribution substation

Demand analysis of the information sharing among multi-bays ...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： YueLin Yang Bin Wang BoYing Wen XinZhou Dong TingTing Wu Kun Liu College Of Information and Electrical Engineering CHINA Agricultural University Beijing 100083 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China School of Electrical Engineering & Renewable Energy China Three Gorges University Yichang 443000 China

Multi-bay information sharing has very important significances for the the enhancing of the relay characteristics and improving of the system control methods. With the summary of distribution substation busbar protection, small current grounding fault line selection, non-communication double-circuit line protection, reactive power and voltage control, low frequency load shedding control programmes, It analyse the needs of the information sharing among multiple bays and the application of integrated protection.

关键词： Circuit faults Substations Process control control systems Reliability Automation

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Fault diagnosis of direct-drive wind turbine based on support vector machine

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Journal of Physics: Conference Series 2011年第1期305卷

作者： X L An D X Jiang S H Li J Chen State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

A fault diagnosis method of direct-drive wind turbine based on support vector machine (SVM) and feature selection is presented. The time-domain feature parameters of main shaft vibration signal in the horizontal and vertical directions are considered in the method. Firstly, in laboratory scale five experiments of direct-drive wind turbine with normal condition, wind wheel mass imbalance fault, wind wheel aerodynamic imbalance fault, yaw fault and blade airfoil change fault are carried out. The features of five experiments are analyzed. Secondly, the sensitive time-domain feature parameters in the horizontal and vertical directions of vibration signal in the five conditions are selected and used as feature samples. By training, the mapping relation between feature parameters and fault types are established in SVM model. Finally, the performance of the proposed method is verified through experimental data. The results show that the proposed method is effective in identifying the fault of wind turbine. It has good classification ability and robustness to diagnose the fault of direct-drive wind turbine.

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Nonlinear dynamic characteristic analysis of a vertical mass unbalanced rotor

Nonlinear dynamic characteristic analysis of a vertical mass...

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23rd International Congress on Condition Monitoring and Diagnostic Engineering Management, COMADEM 2010

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

ISBN: (纸本)9784883254194

The dynamic properties between torsional and bending vibrations of a vertical mass unbalanced rotor are described. The equation of rotor system motion is obtained by Lagrangian dynamics without considering the external actuating forces and torque, shows coupling effect and nonlinear interaction between the rotor system bending and torsional vibrations. An attempt of theoretical analysis and numerical simulation is made to reveal dynamic characteristics of a rotor system. Theoretical analysis of the rotor dynamic equations based on perturbation theory indicates that at stable state of vibration the coupled effect on the rotor system is nonexistent and the bending vibration becomes equal amplitude with shafting speed at stable vibration state. While the torsional vibration keeps on attenuating until it stops. In addition, the numerical simulation results to the dynamic equations, show that coupled torsional and bending vibrations are induced by mass eccentricity, and coupled effect can only be found in vibration initial state of the rotor system. Other numerical simulation results are consistent with the theoretical analysis.

关键词： Perturbation techniques

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Evaluation of cascading failure in power system based on the operational reliability theory

Evaluation of cascading failure in power system based on the...

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2010 IEEE 11th International Conference on Probabilistic Methods Applied to power systems, PMAPS 2010

作者： Zou, Xin Cheng, Lin Sun, Yuanzhang Department of Electrical Engineering State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781424457236

According to the characteristics of the cascading failures in power grid, a lot of assessment methods based on the probability theory have been proposed in recent years. However, most of them ignore the influence of the changing operating conditions on the power system planning and operation. This paper assesses the risk of the cascading failure in the power system based on the operational reliability theory which considering the variation of operating states and environment of the power system. The operational reliability of the power system is calculated based on Markov Process which describes the transient probability of states. The key conception of this theory is that the failure rate and the probability of components are changing along with the life of the equipment, the operating states and the environment conditions. A new evaluation procedure is brought up to calculate the operational reliability indices which can provide the specific information of the cascading failure. The evaluating results of the test system confirm that this approach is applicable to analyze the cascading failures in real power system. ©2010 IEEE.

关键词： Reliability theory

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Crack Growth Prediction of the Steam Turbine Generator Shaft

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Journal of Physics: Conference Series 2011年第1期305卷

作者： Dongxiang Jiang Chao Liu 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

The power network in China is encountering great changes and large-scale network is increasingly implemented for long distance power transmission as well as various kinds of power electronic devices, which bring in the risk of the torsional vibration of the turbine generator shafts, may cause the fatigue damage and cracks in the product life cycle. The paper analyzed the failed coupling of some 600MW steam turbine generator and calculated the local stress of the assembly under torsional load caused by the network disturbance. Then the crack propagation was analyzed with the predicted crack initiation position and crack propagation routine. The assembled coupling contains shaft, coupling and keys with interferences between the parts. Therefore the contact analysis was included. Extended Finite Element Method (X-FEM) is used to calculate the crack propagation and that the mesh needs not to be regenerated with the crack propagation, which is beneficial for engineering applications.

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