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作者： Yu, Hong-Qiao Chen, Shui-Ming Yang, Peng-Cheng State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457700668

The cable and transformer are important distribution equipment in Microgrid. Due to the low insulation level, the insulation of them is easily damaged by lightning. The models of high-frequency transformer and the calculation model of induced lightning with transmission line based on electromagnetic transient calculation software PSCAD / EMTDC are designed in this paper. The lightning protection of cables and transformer in Microgrid, the transferred overvoltage of transformer and the effect of the length of cables and the load types to overvoltage level are researched. The conclusion shows that the induced overvoltage and transferred overvoltage could be reduced efficiently after installing surge arrester at the cables and transformer, but the direct lightning overvoltage is not reduced in the safety range;The longer the cables, the lower the overvoltage is;The inductively load can reduce the overvoltage level slightly while the capacitive and resistance loads has no influence. © 2010 Chinese Soc for Elec Eng.

关键词： Electrolysis

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A computer control and monitoring system for high power converters

A computer control and monitoring system for high power conv...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Rong, Yi Zhenming, Zhao Xiaoying, Sun Liqiang, Yuan Jue, Qian Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100086 China

ISBN: (纸本)7506274078

Computer control and monitoring system (CCMS) is quite important for high power converters (HPCs) operation. This paper presents a novel CCMS, which integrates a database management system (DBMS) into the monitoring software to get the beneficial features such as simple configuration and compact structure. In its communication system, an advanced optical fiber communication (OFC) technology is applied and priority-based communications is proposed to improve the reliability and the real time of the communications. Furthermore, a friendly standard Windows human-machine interface (HMI) is provided. The reliability and performance of the system are verified by system tests and practical operations.

关键词： power converters

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Convolution Neural Network-based Load Model Parameter Selection Considering Short-term Voltage Stability

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CSEE Journal of power and Energy systems 2024年第3期10卷 1064-1074页

作者： Ying Wang Chao Lu Xinran Zhang School of Technology Beijing Forestry UniversityBeijing 100083China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua UniversityBeijing 100084China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China IEEE

The recently proposed ambient signal-based load modeling approach offers an important and effective idea to study the time-varying and distributed characteristics of power ***,it also brings new *** the load model parameters of power loads can be obtained in real-time for each load bus,the numerous identified parameters make parameter application *** order to obtain the parameters suitable for off-line applications,load model parameter selection(LMPS)is first introduced in this ***,the convolution neural network(CNN)is adopted to achieve the selection purpose from the perspective of short-term voltage *** begin with,the field phasor measurement unit(PMU)data from China Southern power Grid are obtained for load model parameter identification,and the identification results of different substations during different times indicate the necessity of ***,the simulation case of Guangdong power Grid shows the process of LMPS,and the results from the CNNbased LMPS confirm its effectiveness.

关键词： Ambient signal CNN field PMU data load model parameter selection short-term voltage stability

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Phase-shift control of isolated bidirectional DC-DC converters for unidirectional power flow

Phase-shift control of isolated bidirectional DC-DC converte...

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作者： Ge, Junjie Zhao, Zhengming Ma, Junchao He, Fanbo Yuan, Liqiang Lu, Ting State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781479956982

In the conventional phase-shift control of isolated bidirectional DC-DC converters, the phenomenon of power backflow is quite obvious. General improved phase-shift control methods can reduce the power backflow of the input. However, they do not take the power backflow of the output into consideration. In this paper, a novel phase-shift control of isolated bidirectional DC-DC converters for unidirectional power flow is proposed. It can eliminate the power backflows of both the input and the output at the same time. Furthermore, the converters in the proposed phase-shift control can achieve the zero-current switching in the whole power rang. Experimental results from a prototype verify the feasibility and validity of the proposed control method, and show superior performance. © 2014 IEEE.

关键词： Zero current switching

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Experimental investigation and analysis of some common faults for wind turbine 68

Experimental investigation and analysis of some common fault...

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68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

作者： Yang, Wenguang Li, Shaohua Jiang, Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

This paper focus on the fault characteristic by experimental research. A test rig is built for the direct driving stall fix-pitch horizontal axis wind turbine. 8 signals are collected by the experiment system, including wind speed, rotor rotational speed, shaft torque, the output electric power, vertical and horizontal vibration displacement of main shaft, vibration acceleration of the front bearing pedestal and the back bearing pedestal. 11 common wind turbine faults are researched by experiment. These faults are rotor mass imbalance, pneumatic asymmetry, airfoil changed, yaw fault, shaft horizontal misalignment, shaft vertical misalignment, front bearing pedestal looseness, rear bearing pedestal looseness, front bearing outer ring fault, front bearing inner ring fault, and front bearing roller fault. Several signal analysis methods, which are waveform analysis, orbit analysis, amplitude domain analysis, frequency domain analysis and envelope spectrum analysis, are adopted to extract characteristics from vibration signals. The influence on output power and vibration characteristics of these faults is presented by comparing with normal operation. The findings can be used to guide wind turbine fault diagnosis in engineering applications.

关键词： Wind

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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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2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Zhang, Xiao He, Jinliang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457714665

Lightning overvoltage protection is of great importance to the safety of UHV GIS. The widely used arresters can only suppress the magnitude of lightning overvoltage but lack efficiency on alleviating the steepness. In 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 GIS. Moreover, equivalent model based on the characteristic of ferromagnetic material and factual dimension of the ring is established for calculation. simulation 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. © 2011 IEEE.

关键词： power transformers

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Electromagnetic and Mechanical Transmission Role of Poles in vibration of PMDC motor

Electromagnetic and Mechanical Transmission Role of Poles in...

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2022 International Conference on Electrical Machines, ICEM 2022

作者： Wang, S.M. Gu, Z.Q. Hong, J.F. Yang, Z.L. Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Beijing100084 China

ISBN: (数字)9781665414326

ISBN: (纸本)9781665414326

In this paper, the pivot role of permanent-magnet pole in the electromagnetic and mechanical transfer process of the vibration in PMDC motor is clarified, and the transfer function is established to describe the transfer process of electromagnetic force from the bottom of the magnetic pole to the stator yoke. The expression of radial electromagnetic force in air-gap is analytically calculated, the characteristics of harmonic components are obtained, and the reason why high order force density produces low order concentrated force and bending moment is explained. Based on the characteristics of harmonics, the relationship between the polar arc coefficient and concentrated force or bending moment is explained. Finally, the key role of magnetic poles in the vibration transmission of PMDC motor is summarized. © 2022 IEEE.

关键词： Bending moments

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Optimal design of the back-to-back IGBT-based converter with the concept of systematic safe operating area

Optimal design of the back-to-back IGBT-based converter with...

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2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Zou, Gaoyu Zhao, Zhengming Yuan, Liqiang Wang, Xuesong Lu, Ting State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457710445

The key parameters of SOA (safe operating area) of semiconductor devices are hard to be measured when converter is operating, which is not helpful to protect converter at any time. On the other hand, surplus estimating method is widely used to design the main circuit. In order to guarantee the whole system works safely and improve utilization rate of devices, the concept of SSOA (systematic safe operating area) is presented. By determining the relationship of key parameters between devices and converter, the expression of SSOA is described quantitatively. Then it is implemented as a basic rule to design a back-to-back converter based on IGBT for 55kW induction motor optimally. Rated value of DC-link voltage and grid filter of the system is obtained reasonably as well. © 2011 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

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Experimental investigation and analysis for gearbox fault

Experimental investigation and analysis for gearbox fault

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2010 2nd World Non-Grid-Connected Wind power and Energy Conference, WNWEC 2010

作者： Li, Shaohua Jiang, Dongxiang Zhao, Minghao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781424489213

As an important component of a wind turbine drive chain, the high failure rate of the gearbox can have a serious impact on the operation of wind turbine units. The fault diagnosis of the gearbox is therefore important for the safety of wind turbine units. In this paper, a gearbox experiment rig was built, experiments on the gear surface spalling fault were held on the rig under laboratory conditions, the shaft vibration displacement signals were collected, related vibration signals were analyzed by time domain, amplitude domain, frequency domain and wavelet analysis, and the results of different analysis methods were compared. The results show that the waveform of normal and fault signals are similar, the amplitude of the signals will change while the fault happens, and the wavelet analysis is more effective than frequency domain analysis on gearbox fault features extraction. © 2010 IEEE.

关键词： Frequency domain analysis

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Electrical properties of oil-paper insulation affected by water conductivity during paper-making process

Electrical properties of oil-paper insulation affected by wa...

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32nd Electrical Insulation Conference, EIC 2014

作者： Huang, Jianwen Zhou, Yuanxiang Jin, Fubao Sha, Yanchao Zhang, Ling Le, Trung Hieu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781479927876

Developments of ultra-high voltage grid in China require better insulation materials, and that forces the transformer presspaper and pressboard manufactures to pay more attention to the papermaking process to enhance their product qualities. In this study, pure water and three kinds of sodium chloride solutions with conductivities of 100 μS/cm, 500 μS/cm and 1000 μS/cm were respectively used to prepare presspaper samples. By vacuum impregnation, four kinds of oil-paper samples were acquired. Test results showed that relative permittivity and tand of oil-paper specimens first varied little then increased a lot with the increasing of water conductivity;DC breakdown field decreased while AC breakdown field changed little. To confirm the differences were due to water conductivity, ion chromatography was used to determine the sodium and chloride ion contents of the presspaper samples, we found that the ion contents increased with electrical conductivity. This indicates that water conductivity does have effects on most electrical properties of oil-paper insulation and lower conductivity can bring better insulation performances. © 2014 IEEE.

关键词： Ion chromatography

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