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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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Traveling waves based faulted feeder selector and its field application

Traveling waves based faulted feeder selector and its field ...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Shi, Shenxing Wang, Jun Li, Aiming Du, Xinchun Cao, Xiaoxia Du, Yajun Dong, Xinzhou State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Yulin Power Company Shaanxi 719000 China China Jiuquan Satellite Launch Center Plumbing Electrical Station Jiuquan 732750 China

ISBN: (纸本)9781424496198

The paper proposes faulted feeder selector in power distribution system with neutral non-effectively grounded. At first, the paper presents basic principle of single-phase-to-ground fault feeder selection based on traveling waves, which compares amplitude and polarity of the initial current traveling waves in all feeders. Then the implementation scheme, including hardware design and software flowchart is presented. At last field application of faulted feeder selector is introduced. The field operation results validated the correctness of faulted feeder selector based on transient traveling wave. © 2011 IEEE.

关键词： Electric grounding

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Study on Over-Voltage of 220 kV Transformer＇s Neutrals and Protection Strategy

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Journal of Energy and power Engineering 2011年第11期5卷 1102-1108页

作者： H.P. Yu S.M. Chen P.C. Yang H. Yin G.L. Wu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beoing 100084 China Chongqing Electric Power Research Institute Chongqing 401123 China

In order to limit short-circuit current and satisfy the need of relay setting, only part of the 220 kV power transformer is grounded, so on the neutrals of ungrounded transformers will appear the over-voltage. Currently the value of over-voltage on transformer neutral point and the corresponding protection strategy is based on theoretical formula. This article uses the PSCAD/EMTDC software to calculate the over-voltage on the neutral point of 4 ungrounded power transformers in Chongqing 220 kV power grid. The result shows that the power frequency transient over-voltage on the neutrals may reach 178 kV. If the single-phase grounding fault occurs in ungrounded power system, the power frequency over-voltage on the neutrals will be more serious and rise to 138.6 kV. Non-full phase operation may cause serious ferro-resonance over-voltage on the neutrals of no-load transformer, which may last for seconds and may rise to 723.7 kV, causing serious threat to the transformer neutrals and line-side equipment. The article also studies the gap parameter which should be taken on the neutrals of 220 kV transformers at the end.

关键词： Neutral point power transformer arrester gap power frequency over-voltage lightning over-voltage.

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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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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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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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The research of synchronized phasor measurement units in smart substations

The research of synchronized phasor measurement units in sma...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Xu, Yong Zhang, Dao-Nong Yu, Yuehai Status Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China China Electric Power Research Institute Haidian District Beijing 100085 China North China Power Engineering Co. Ltd. Beijing 100120 China State Grid Electric Power Research Institute Nanjing 210061 China

ISBN: (纸本)9781424496198

Smart substation is the base of smart grid and it is made up of a lot of IEDs (intelligent electric device). Synchronized phasor measurement unit (PMU) plays a very important role in the smart grid, and a great deal of PMUs have been installed in China. The requirement of PMU in the smart substation is different from traditional substation. This paper introduces that the PMU is suitable for smart substation, there are several details that need to be complemented in IEC 61850 standards, and the paper gives some suggestion to improve it. © 2011 IEEE.

关键词： Phasor measurement units

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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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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Xu, Fei Wang, Bin Dong, Xinzhou Cao, Runbin Liu, Kun Yang, Yuelin Wu, Tingting State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China College of Information and Electrical Engineering China Agricultural University China School of Electrical Engineering and Renewable Energy China Three Gorges University Yichang 443000 China

ISBN: (纸本)9781424496198

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. © 2011 IEEE.

关键词： Ethernet

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Applicable range analysis of optimized single-terminal fault location algorithm

Applicable range analysis of optimized single-terminal fault...

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

作者： Tian-xiao Huang Xin-zhou Dong Shen-xing Shi Bin Wang State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

Impedance method and single terminal travelling wave method are analyzed in paper, applicable scope of optimized solution is presented. Impedance method is of high robustness but low accuracy. Single terminal travelling wave method offers high accuracy but poor robustness. Optimized solution combines these two methods together, takes advantages of both methods. It is a great enhancement to single terminal fault location. This paper analyzed theoretical basis of optimized solution, proposed the calculation algorithm of fault location range using impedance method. Analyses of impedance method and single terminal travelling wave method show that the optimized solution is suitable for engineering application. Error analysis is proved correct by simulation.

关键词： Fault location Impedance Impedance measurement Transmission line measurements power transmission lines Frequency modulation Surges

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Research on the process of power flow transferring and its identification method

Research on the process of power flow transferring and its i...

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

作者： Kun Liu Xinzhou Dong Bin Wang Shenxing Shi State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

This paper analyzes the general process of power flow transferring and divides it into four parts: 1) the process of first phase selection after fault occurs; 2) the process of selective action at the first time; 3) the process of second phase selection and status confirmation; 4) the process after status confirmation. It points out that the issue of asymmetrical flow transferring is a critical process which must be put emphasis on. Then it proposes a method to identify this process, and discuss different solution methods.

关键词： Circuit faults Fault diagnosis Grounding Voltage measurement Protective relaying Oscillators Impedance

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