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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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An Improved Virtual Resistance Damping Method for Grid-Connected Inverters with LCL Filters

An Improved Virtual Resistance Damping Method for Grid-Conne...

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2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011)

作者： Yi Lei Zhengming Zhao Fanbo He Sizhao Lu Lu Yin State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University 100084 Beijing P. R. China

ISBN: (纸本)9781457705427;9781457705410

In renewable energy generations, LCL filters are commonly used to connect in series with the output ports of the converter to smooth the currents flowing into the grid due to their enhanced attenuation ability and smaller inductance compared to single L filters. However, the inherent resonance of an LCL filter makes the control of such a system challenging, and different passive and active damping strategies have been developed till now. This paper aims to the damping problems of LCL filters and proposes a new approach to realize active damping. Based on traditional virtual resistance damping strategy, the new algorithm employs a lead compensation block in the capacitor current feedback loop so as to alleviate the impact of control delay. It is easy to be transformed from conventional virtual resistance damping method since just an additional digital filter is needed. Theoretical analyses for the essence equivalent relationship between passive damping and virtual resistance damping, as well as the impact investigation of control delay are made in details. The results show that the traditional virtual resistance active damping method is equivalent to passive damping of connecting damping resistance in parallel with the capacitor in the control block diagram, while the proposed virtual resistance active damping method is equivalent to passive damping of connecting damping resistance in series with the capacitor in the control block diagram. Both simulation and experimental results have verified the feasibility.

关键词： absorption of shock BLOCK DIAGRAM Capacitors Filters Virtual Equivalent damping force control block

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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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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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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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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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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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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 Generalized Leakage Inductance-Based Method for Discrimination of Internal Faults from Inrush Currents

A Generalized Leakage Inductance-Based Method for Discrimina...

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IEEE power and Energy Society General Meeting

作者： Jing Ma Tong Wang Jie Wu Zengping Wang School of Electrical and Electronic Engineering North China Electric Power University Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University State Nuclear Electric Power Planning Design and Research Institute

ISBN: (纸本)9781457710001

A novel scheme based on generalized leakage inductance (GLI) to distinguish the inrush current from the internal fault current in the power transformer is proposed. By eliminating the mutual flux linkage in the transformer loop equation and adopting the trapezoid principle, the GLI is calculated in the real time. According to the difference between the GLI and the leakage inductance obtained from transformer manufacturer, the criterion to identify the internal fault is developed. A total of 162 experimental cases have been tested and the proposed method is able to reliably and accurately discriminate internal faults from inrush currents with easy implementation. Also, the method is suitable if it is not possible to measure the currents in the delta winding. Furthermore, the method is independent of the B-H curve and iron losses.

关键词： Generalized leakage inductance Inrush current Internal fault current power transformer Inrush current internal fault ELECTRIC TRANSFORMERS currents INFLUX ocean currents water currents magnetization curve fault currents Extravasation Transformer Core loss

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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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