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2011 International Workshop on Computer Science for Environmental Engineering and EcoInformatics, CSEEE 2011

作者： He, Qing Zhao, Xiaotong Zhang, Jianding Huang, Xiaobin National Engineering Laboratory for Biomass Power Generation Equipment School of Energy Power and Mechanical Engineering North China Electric Power University Beijing 102206 China Division of Power System China Electric Power Research Institute Beijing 100192 China School of Control and Computer Engineering North China Electric Power University Beijing 102206 China

ISBN: (纸本)9783642226939

Under the given operation condition, the operating parameters of large-scale fan vary according to certain rule. With the fan aging, the rule is changing. In order to find the rule of deterioration of condition parameters of fan, the factor analysis is used to analyze condition parameters of fan, which date from different period under the same operation condition. It is proved by the examples that factor analysis is suitable for analyzing fan deterioration. © 2011 Springer-Verlag.

关键词： Deterioration

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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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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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A parallel based real-time electromagnetic transient simulator for IPS

A parallel based real-time electromagnetic transient simulat...

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IEEE Electric Ship Technologies Symposium, ESTS

作者： Yuan Gong Laijun Chen Ying Chen Yin Xu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

IPS has many special characteristics, such as using multi-phase, multi-frequency and hybrid AC/DC devices. As a result, existing electromagnetic transient simulators developed for power systems on land do not apply to IPS. This paper aims to build up a parallel based real-time electromagnetic transient simulator for IPS. A fast multi-switching process method for parallel electromagnetic transient simulations is coined to handle the tremendous switch events in IPS. To solve the difficulties brought by multi-phase machines in IPS, a multilevel hybrid parallel algorithm is forged through the combination of component level and network level parallelization. Based on the key techniques mentioned above, a parallel simulator is built up. Through sufficient testing to typical examples of IPS, the accuracy and high-efficiency of the simulator are proved.

关键词： Computational modeling Switches Generators Real time systems Parallel algorithms Circuit faults Testing

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Lightning Overvoltage Suppression of power Transformer in UHV GIS by Ferromagnetic Ring

Lightning Overvoltage Suppression of Power Transformer in UH...

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第七届亚太防雷国际会议

作者： Xiao Zhang Jinliang He State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Lightning overvoltage protection is of great importance to the safety of UHV *** widely used arresters can only suppress the magnitude of lightning overvoltage but lack efficiency on alleviating the *** practice, insulation failure of UHV transformer is often reported.A new protection method is proposed in this paper using ferromagnetic ring as supplement to arresters to suppress lightning overvoltage in UHV ***, equivalent model based on the characteristic of ferromagnetic material and factual dimension of the ring is established for *** of an actual 1000kV GIS is carried out to thoroughly evaluate the lightning overvoltage suppressing effect of ferromagnetic rings with different materials and structure dimensions.

关键词： ferromagnetic ring lightning overvoltage UHV

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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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A DC-link Voltage control Scheme for Single-phase Grid-connected PV Inverters

A DC-link Voltage Control Scheme for Single-phase Grid-conne...

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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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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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Effect of Different Arresters on Switching Overvoltages in UHV Transmission Lines

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Tsinghua Science and Technology 2010年第3期15卷 325-328页

作者：杨鹏程陈水明何金良 State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress switching overvoltages in UHV transmission lines. Switching overvoltages on the 1000 kV Huainan-Huxi double-circuit transmission line were simulated for different operating modes and different arrester designs using the electromagnetic transient program PSCAD/EMTDC. With parallel resistors, the switching overvoltages are less than 1.70 p.u. （1.0 p.u.=1100×√ 2 /√3 kV）. If the arrestors are better, the switching overvoltages can be reduced even lower to 1.55 p.u. Without parallel resistors, the arresters can reduce three-phase energizing overvoltages to 1.70 p.u, while the single-phase reclosing overvoltages still exceed the limit. The results show that the parallel resistors cannot be eliminated if the arresters are only installed at each end of the transmission line. Also, better quality arresters significantly lower the switching overvoltages.

关键词： UHV double-circuit transmission line switching overvoltages arresters

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Voltage Fluctuation Suppression Method of Floating Capacitors in a New Modular Multilevel Converter

Voltage Fluctuation Suppression Method of Floating Capacitor...

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2011 IEEE Energy Conversion Congress and Exposition (ECCE 2011)

作者： Kui Wang Yongdong Li Zedong Zheng Lie Xu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781457705427

Modular multilevel converter (MMC) is a newly emerging multilevel topology for high power applications in recent years. The voltage fluctuation problem of a new MMC topology is studied in this paper. In order to suppress the voltage fluctuation of the floating capacitors, a control method is proposed by injecting high frequency zero-sequence voltage and phase-to-phase circulating currents. It can be used to drive an induction motor with pump/blower-like load at low speed and improve the performance significantly. A low power three-phase five-level prototype is built up to validate this method.

关键词： Bridge circuits Fluctuations Capacitors Voltage fluctuations Voltage control Frequency modulation Time frequency analysis

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