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The 2011 International Conference on Electric and Electronics (EEIC 2011)

作者： Jidong Wang Kun Liu Guanqing Yang Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University

The rapid detection of characteristics of voltage sag is an important prerequisite for using dynamic voltage restorer(DVR) for voltage compensation. This paper introduced an improved derivation detection method based on dq transformation. simulation was performed to analyze the advantages and disadvantages of both methods and compare them. Results showed that the improved detection method had shorter delay and better waveform of detection and met the requirements of accuracy and timeliness better.

关键词： voltage sag detection method dq transformation derivation

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power Quality Improvement for Mircrogrid in Islanded Mode

Power Quality Improvement for Mircrogrid in Islanded Mode

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2011 International Conference on power Electronics and Engineering Application

作者： Gao Xiaozhi Li Linchuan Chen Wenyan Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University

The aim of this paper is to analyze and improve the power quality of island microgrid assuming that the distributed generators could meet the load active power requirement. The main power quality problems through analysis are the harmonics caused by power-electronic devices and voltage variation caused by high reactive power requirement. Based on economy and compensation performance, a combined system constructed by SVC and SAPF is designed to improve the power quality of microgrid in this paper, in which SAPF is adopted near the microsource to mitigate harmonic currents and SVC near the load to compensate reactive power so as to relieve the voltage variation. simulation results show the effectiveness of the combined system.

关键词： v/f control scheme microgrid power quality APF SVC

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Experimental Research of the Upward Leader Inception from Transmission Line

Experimental Research of the Upward Leader Inception from Tr...

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第七届亚太防雷国际会议

作者： Zhizhao Li Rong Zeng Zhanqing Yu Chijie Zhuang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department

Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission *** with the increase of operation voltage to 1000 kV and tower height to more than 100 meters, some shortcomings of the traditional EGM model were found by many *** Progression Model (LPM) was proposed to solve these *** some fundamental works, such as when the upward leader initiates and how it propagates, is still *** experiment was designed and implemented in this paper to simulate the electric field circumstance near the test transmission line while the lightning downward leader *** upward leader from the test transmission line was clearly *** inception voltage and characteristics was *** streamer and leader initiated from the ground wire and conductor bundle were *** experiment results show that the leader initiating from the ground wire is more active in the inception *** velocity of the upward leader acquired is about 1.2-3.0 cm/μs.

关键词： lightning shielding failure upward leader inception leader progression model simulating experiment

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A novel algorithm for distribution network reconfiguration based on evolutionary programming

A novel algorithm for distribution network reconfiguration b...

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

作者： Bingda Zhang Liu Yang Key Laboratory of Power System Simulation and Control (Tianjin University) Ministry of Education 300072 China Key Laboratory of Power System Simulation and Control (Tianjin University) Ministry of Education (of Affiliation) Tianjin China

Because there are slow evolutionary process and difficult smooth convergence in evolutionary programming algorithm, a mutation operator for distribution network reconfiguration is proposed. In order to guarantee that new individuals from mutation is close to the optimal individual actively, times of topology restructure should be inversely proportional to evolutionary generations, and both selection operators for switch to open and to close should be set in the process of topology restructure. Simplified calculation methods of power loss of network, quadratic load moment and selection operators are given. The feasibility of method proposed above is verified in the system of the operation optimization and the assistant decision of the 10kV distribution network, which is located in Shangqiu power supply bureau, Henan Province.

关键词： Switches Topology Equations Load flow analysis Programming

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Numerical simulation on Small Scale Straight-blade and Twisted-blade Vertical Axis Wind T

Numerical Simulation on Small Scale Straight-blade and Twist...

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2011 SSITE International Conference on Future Material Research and Industry Application(FMRIA 2011)

作者： Lv Yongzhe Jiang Dongxiang Jiang Yong State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University

This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straight-blade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT)An attempt of this simulation is to identify which type performs better in the same wind conditions and swept areaThree-dimensional computational fluid dynamics(CFD) was adopted in this analysis, after solid models of them were generatedPreliminary results of torque, power and aerodynamics in the fluid field were obtained for discussionFinally, there provided some guidance for future wind tunnel tests.

关键词： straight-blade vertical axis wind turbine twisted-blade vertical axis wind turbine numerical simulation performance aerodynamics

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Numerical simulation on Small Scale Straight-blade and Twisted-blade Vertical Axis Wind Turbine

Numerical Simulation on Small Scale Straight-blade and Twist...

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2011 International Conference on Energy and Environment(ICEE 2011)

作者： Lv Yongzhe Jiang Dongxiang Jiang Yong State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University

This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straightblade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT). An attempt of this simulation is to identify which type performs better in the same wind conditions and swept area. Three-dimensional computational fluid dynamics(CFD) was adopted in this analysis, after solid models of them were generated. Preliminary results of torque, power and aerodynamics in the fluid field were obtained for discussion. Finally, there provided some guidance for future wind tunnel tests.

关键词： straight-blade vertical axis wind turbine twistedblade vertical axis wind turbine numerical simulation performance aerodynamics

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Study on the loss reduction of high-efficient high-voltage series induction motors

Study on the loss reduction of high-efficient high-voltage s...

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2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Lingyun, Bai Zhengming, Zhao Yi, Lei Shuping, Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China Beijing Command College of CAPF Beijing 100012 China Anhui Electrical Research Institute Hefei 230022 China

ISBN: (纸本)9781457710445

On the basis of analyzing the composition of losses in high-efficient high-voltage asynchronous motors, the approaches of increasing the efficiency of the motors is investigated in this paper. The approaches concern with the improvement of material, winding, fan, magnetic groove and so on. By taking the economy and efficiency into account synthetically, the design of the YKK series induction motors is carried on, and it is realized by software simulation. © 2011 IEEE.

关键词： Induction motors

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Effects of nonlinear gradient index on radiative heat transfer in a one-dimensional medium by the DRESOR method

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Journal of Physics: Conference Series 2012年第1期369卷

作者： Z C Wang Q Cheng G H Wang Z F Huang H C Zhou State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 Hubei People's Republic of China State Key Laboratory of Control & Simulation of Power System & Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 10084 P. R. China To whom any correspondence should be addressed

The DRESOR (Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface) method is applied for radiative heat transfer in a one-dimensional medium with a nonlinear gradient index and gray boundary surfaces. In this proposed method, the DRESOR values calculated by the Monte Carlo method express quantitatively the impact of scattering on radiative transfer and the radiative intensity with high directional resolution of high precision can be easily obtained. With given media characteristics and boundary conditions, the temperature and radiative flux distributions inside the medium are calculated under the condition of radiative equilibrium. It is shown, in the cases studied, that the DRESOR method has a good accuracy. The temperature distributions have a node with different kinds of sine changed gradient index distributions under the same boundary emissivity. The impact of the gradient index on the radiative heat transfer is considerable, and the same as that of the ratios of its amplitude and average index. Besides, the effects of optical thickness, boundary emissivity and scattering phase function on radiative transfer also should be paid adequate attention.

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simulation of gas flows in micro/nano systems using the Burnett equations

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Journal of Physics: Conference Series 2012年第1期362卷

作者： Fubing Bao Xia Yu Jianzhong Lin Institute of Flow Measurement and Simulation China Jiliang University Hangzhou 310018 China Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

The gaseous flow characteristics in micro/nano systems are studied using the Burnett equations. The Burnett equations are the second-order approximation of the Chapman–Enskog solution to the Boltzmann equation. This set of equation is appropriate to describe the rarefied gas flows. Velocity slip and temperature jump boundary conditions are applied on solid surface. Several techniques, including the usage of relaxation method on slip values and Burnett terms, are introduced to increase the stability of the Burnett equations. Hence, convergent results at Knudsen number up to 0.5 are achieved for the first time. The results of the Burnett equations are first verified using the corresponding experimental and the DSMC data. The Navier-Stokes and the Burnett equations give almost the same result when the flow is in slip regime (Kn<0.0l). But when the flow is in transition regime (0.1systems. The pressure driven plane Poiseuille and the backward-facing step flows, the flows through micro filters are then studied. Different inlet to outlet pressure ratios, size effects, shape effects and boundary conditions are analyzed. The competitive relations of rarefied and compressible effects in micro gas flows are discussed.

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A Study on Capacity of Distributed Generation and its Effect on Short Circuit Current at Microgrid Operation Mode

A Study on Capacity of Distributed Generation and its Effect...

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2011 4th International Conference on Electric Utility Deregulation and Restructuring and power Technologies(第四届电力设施管制、重建及能源技术国际会议 DRPT 2011)

作者： JIN Qiang ZHANG Shuo LI Yong-li Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University Tianjin China

Now more and more distributed generations will be connected to distributed power ***'s found that different distributed generation has its own operation characteristic such as fluctuation and *** micro-grid is to be island the voltage and frequency will change,so different control modes have been used on different distributed *** kinds of distributed generation have different behavior when system operates normally or fault *** and equivalence were adopted to deal with all kinds of the distributed generations in *** distributed generations with same control mode can be combined to an equivalent *** system operates on grid-connection mode the short circuit current relies on the capacity of grid so it is rather large for the capacity of distribution grid is much more than that of distributed *** when micro-grid operates on island mode the short circuit current may decrease to a relative small *** current protection is widely used in distribution system,and the performance of it is dependent on operation mode,so the value estimate of short circuit current is necessary for verification of credibility and *** summations of capacity were proposed to estimate the minimum and maximum short-circuit current in island.

关键词： capacity of distributed generation :equivalent capacity:short-circuit current:operation mode:over current protection

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