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International Conference on Electrical Machines and systems (ICEMS)

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

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.

关键词： Magnetic flux Windings Induction motors Rotors Perpendicular magnetic anisotropy Copper

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Research of a novel PWM static VAR compensator based on AC_Buck voltage converter

Research of a novel PWM static VAR compensator based on AC_B...

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IEEE Conference on Industrial Electronics and Applications (ICIEA)

作者： Le-zhu Chen Yi-jun Ge Ye-ce Qian Peng-cheng Yi Ling-ling Nie Key Laboratory of Power Electronics & Motion Control Anhui University of Science and Technology Ma'anshan China State Key Laboratory of Power System Tsinghua University Beijing China

This paper proposals a novel hybrid static var compensator, which can adjust capacitor continuously. The proposed compensator combines the PWM type AC_Buck converter with the transformer to adjust the voltage on the compensating capacitor directly. So the continuous output of reactive power is realized. The compensator has fast dynamic response, and produces no harmonic. The capacity of the transformer is only 25% of that of the compensating capacitor. Operation Principle of the compensator is elaborated in this paper, and the equations for the power of compensator and inverter are deduced. Experiment results verify the feasibility and effectiveness of the compensator.

关键词： Reactive power Capacitors Harmonic analysis power system dynamics Switches power harmonic filters

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Research on earthing schemes in LV microgrids

Research on earthing schemes in LV microgrids

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

作者： BoTong Li YongLi Li Tao Ma Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University 300072 China Junliangcheng Power Co. Ltd. China Huadian Tianjin 300300 China

For the access of green distributed generation(DG), LV microgrid is an important direction of development nowadays. Because the LV microgirds are in direct contact with users, so how to design its earthing scheme is the first thing to think about in order to guarantee personal safety and reliable operation of the equipments. Earthing schemes of LV mircrogrids are studied in the paper and how it works properly is presented. The principles of neutral earthing modes of microgrid is given according to standard IEC60364 and DGs neutral earthing mode is discussed under different operation modes. How the traditional protection modes of TN and TT are used in LV microgrids is studied. Considering the dispersion and variety of DGs and energy storage devices, combined earthing mode of TN and TT is proposed as a reasonable way for microgrids.

关键词： Grounding Conductors Buildings Earth Laboratories Automation

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Modeling and analysis of MW-level grid-connected PV plant

Modeling and analysis of MW-level grid-connected PV plant

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Annual Conference of Industrial Electronics Society

作者： Yi Lei Zhengming Zhao Wei Xu Jianguo Zhu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China School of Electrical Mechanical and Mechatronic Systems University of Technology Sydney Australia

This paper focuses on the modeling and analysis of the basic composition, characteristic and the interactions with grid for megawatt (MW)-level large scale grid-connected photovoltaic (PV) plants. For a MW-level PV plant, numbers of inverters with relatively smaller capacity are employed to operated in parallel. When the irradiance on the large area of PV array is not equal, the output power verses the voltage of the PV array will have several peak values and affect the maximal power tracking. LCL filters are adopted for filtering the harmonics generated by inverters, but due to its inherent resonance character, additional damping strategy is required. The power quantity of harmonics and voltage fluctuation may occur when one MW-level PV plant is connected to grid. For these characteristics, with the modeling and simulation of a real MW-level PV plant, this paper proposed and verified a novel method toward MPPT of large area PV arrays. The parallel running of inverters and grid voltage fluctuation are also simulated. Finally, the interaction with the grid voltage fluctuation is explored in detail.

关键词： Inverters Arrays Photovoltaic systems Fluctuations Voltage fluctuations

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Stability Analysis of Two‐dimension Burnett Equations

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AIP Conference Proceedings 2011年第1期1376卷 94-96页

作者： Z. H. Zhu F. B. Bao J. Z. Lin J. X. Wang aInstitute of Fluid Measurement and Simulation China Jiliang University Hangzhou 310018 China bDepartment of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

Stability analyses of two‐dimension conventional Burnett and Woods equations were carried out. The characteristic stability equations of these two equations were first derived and the characteristic curves were achieved. The linearized stability analyses show that the two‐dimension conventional Burnett and Woods equations are not stable. The critical Knudsen numbers for these two extended hydrodynamic equations are 0.353 and 0.130, respectively. The critical Knudsen numbers are smaller than those of one‐dimension equations. The two‐dimension extended hydrodynamic equations are more unstable than one‐dimension equations.

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Dynamic Behavior of Space Charge in Epoxy/Metal-Oxide Nano-composite

Dynamic Behavior of Space Charge in Epoxy/Metal-Oxide Nano-c...

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International Symposium on Electrical Insulating Materials

作者： B. X. Du L. Yang J. W. Zhang Y. Gao Key Laboratory of Power System Simulation and Control of Ministry of Education Tianjin University

ISBN: (纸本)9784886860743

Epoxy resin (EX) has been widely used as electrical insulating materials in power systems. It is important to assess the situation of EX insulating materials. As a major factor to result in the deterioration of insulating materials, the space charge behavior in the EX materials is investigated in this paper. To investigate the effect of nano segmentation on the insulation performance and space charge behavior, the testing samples were made by adding two kinds of nano-scale metal oxides into EX materials, divided by the weight ratios of 3, 5, 7 wt%. A pair of aluminum foils attached to both sides of sample surface, make the electrode pattern. After being charged by a DC power source, Thermal Step Method (TSM) was utilized to determine the charge density and electric field distribution of the samples, which involved applying a thermal step (usually 30℃) to short-circuited insulating samples and simultaneous measurement of current response in the external circuit. The space charge density and electric field distribution can be calculated in terms of the response current. Results obtained show space charge density and electric field distribution vary according to the ratio and dispersion of nano-scale SiO_2 added into the samples, providing valuable information for the improvement of insulating materials and a novel way to qualitatively assess the dispersion of nano fillers.

关键词： Space charge Thermal pulse Metal-oxides Epoxy Nanocomposite Dispersion

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A multi-class pattern recognition method for motor imagery EEG data

A multi-class pattern recognition method for motor imagery E...

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2011 IEEE International Conference on systems, Man, and Cybernetics, SMC 2011

作者： Fang, Yonghui Chen, Minyou Harrison, Robert F. State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University Chongqing China Department of Automatic Control and Systems Engineering University of Sheffield Sheffield S1 3JD United Kingdom School of Electronic and Information Engineering Southwest University Chongqing China

ISBN: (纸本)9781457706523

The Common Spatial Patterns (CSP) algorithm is useful for calculating spatial filters for detecting event-related desynchronization (ERD) for use in ERD-based brain-computer interfaces (BCIs). However, basic CSP is a supervised algorithm suited only to two-class discrimination;it is unable to solve multiclass discrimination problems. This paper proposes a new method named the binary common spatial patterns (BCSP) algorithm to extend the basic CSP method to multi-class recognition. Our method arranges the spatial filters and Fisher classifiers in the form of a binary tree whereby N - 1 spatial filters and N - 1 Fisher classifiers are calculated for N class recognition. This is fewer than must be calculated in other methods (e.g. one-versus-rest, OVR). This makes the overall classification procedure less redundant. simulation results show that BCSP has better performance than the OVR scheme and outperforms the three best teams in the 2008 BCI-competition. © 2011 IEEE.

关键词： Brain computer interface

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Transient interaction of HVAC and HVDC in converter station in HVDC, II: Equivalence circuit in AC side and steady-state debugging

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Gaodianya Jishu/High Voltage Engineering 2011年第3期37卷 537-547页

作者： Chen, Shui-Ming Huang, Lu-Lu Xie, Hai-Bin Yu, Zhan-Qing State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

The interaction of nanoseconds, microseconds, milliseconds electromagnetic transients due to AC-DC system operation and fault, the DC converter valve movement, the load generated by changes in the interaction of AC-DC interconnected system electromagnetic transient, can pose a hazard on AC and DC power systems, in particular, lead to the commutation of DC system failures and artesian such serious incidents. Combining theoretical analysis with test, we can establish the analysis method of electromagnetic transient of the full-wave process of the UHV system based on AC-DC interconnected system, control systems, and underground grounding system, and focus on the equivalence circuit of AC side network with the Ward method of equivalency under many operation modes and steady-state debugging for the analysis of AC-DC interconnected system, so as to lay the foundation for the interaction of electromagnetic transient.

关键词： Timing circuits

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Parameter uncertainty analysis in watershed total phosphorus modeling using the GLUE methodology

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Agriculture, Ecosystems & Environment 2011年第3-4期142卷 246-255页

作者： Yongwei Gong Zhenyao Shen Qian Hong Ruimin Liu Qian Liao State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China Key Laboratory of Urban Stormwater System and Water Environment Ministry of Education School of Environment and Energy Engineering Beijing University of Civil Engineering and Architecture Beijing 100044 China

Deterministic watershed models are frequently used for agricultural non-point source (NPS) pollution simulations. However, parameter uncertainty should be analyzed before the modeling results are used to make decisions regarding watershed NPS pollution control programs. In this study, the Soil and Water Assessment Tool (SWAT) was used to simulate the total phosphorus (TP) loads caused by NPS pollution in the upper Daning River Watershed in China's Three Gorges Reservoir Area. The Generalized Likelihood Uncertainty Estimation (GLUE) methodology was used to analyze the parameter uncertainty in SWAT modeling. The impacts of three subjective options of GLUE, the parameter ranges, the level of confidence, and the threshold value of the likelihood measure, on the parameter uncertainty analysis results were analyzed. Specifically, we investigated if there was a combination of these factors that was most appropriate for expression of the uncertainty assessment results. The results indicated that the “observed data” may not always lie within the confidence intervals of GLUE, so the confidence interval was not sufficient to represent the uncertainty for the specific requirements of this study. Therefore we suggest there should be alternative measures to express the parameter uncertainty of GLUE.

关键词： SWAT Non-point source pollution Parameter range Confidence limit Threshold value Confidence interval

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Island partition of the distribution system with distributed generation

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Science China(Technological Sciences) 2010年第11期53卷 3061-3071页

作者： WANG XuDong LIN JiKeng Key laboratory of Power System Simulation and Control of Ministry of Education Tianjin UniversityTianjin 300072China

In this paper, a novel optimum island partition model based on Tree Knapsack Problem (TKP) is presented for the distribution system integrated with distributed generation (DG), and a Depth-first Dynamic Programming Algorithm (DPA) is used to solve this model. With the considerations of the load priority, controlled/uncontrolled loads, and the constraints of power balance, voltage and equipment capacity, the model can meet the practical engineering requirements very well. The island partition problem of the distribution system integrated with multiple DGs is first decomposed into multiple TKPs, each of which is solved by DPA respectively. Then, the initial optimum island partition scheme is gained through an island combination procedure, and the final island partition scheme is obtained after feasibility checking and adjustment. Since the algorithm proposed owns the advantages of strong theoretical foundation and low computational complexity, it can find the approximate optimal solution within a limited time. The results of examples demonstrate the validity of the new model and algorithm.

关键词： optimum island partition distribution system distribution generation(DG) Tree Knapsack Problem(TKP) Depthfirst Dynamic Programming Algorithm(DPA)

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