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18th International Conference on AC and DC power Transmission, ACDC 2022

作者： Guo, Peiqian Zhao, Yuming Liu, Guowei Yuan, Zhichang Wu, Aijun Wang, Yuxuan Jiang, Zhilin Xiang, Miaoyi State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Shenzhen Power Supply Corporation Shenzhen China

ISBN: (数字)9781839537615

ISBN: (纸本)9781839537615

The large number of nonlinear loads used in urban metro rail traction grids distorts the voltage and current on the load side, then generates harmonics. The resulting capacitive characteristic harmonics current component provides feedback to the power grid, thus causing additional power losses and equipment damage. To solve this power quality problem, a detailed dynamic simulator of the metro traction power supply system is developed, which includes the corresponding 24-pulse rectifier and low-voltage power distribution system. Based on the established simulator, a study of the harmonic content and characteristics research of the 24-pulse rectifier and low-voltage electricity-consuming equipment are performed. In combination with the digital simulator, we presented and disused the lower-order frequency harmonic currents of the 35kV AC bus exhibiting capacitive characteristics. The results lay a technical foundation for harmonic equivalent impedance calculation and harmonic current suppression of the metro traction power supply system. © ACDC 2022. All rights reserved.

关键词： Simulators

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Optimal Auxiliary Frequency control of Wind Turbine Generators and Coordination with Synchronous Generators

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CSEE Journal of power and Energy systems 2021年第1期7卷 78-85页

作者： Ming Sun Yong Min Lei Chen Kaiyuan Hou Deming Xia Hangyin Mao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China with Northeast Branch of State Grid Corporation of China Shenyang 110180Liaoning ProvinceChina with State Grid Zhejiang Electric Power Co.LTD. Hangzhou 310007Zhejiang ProvinceChina

Auxiliary frequency control of a wind turbine generator(WTG) has been widely used to enhance the frequencysecurity of power systems with high penetration of renewableenergy. Previous studies recommend two types of control schemes,including frequency droop control and emulated inertia control,which simulate the response characteristics of the synchronousgenerator (SG). This paper plans to further explore the optimalauxiliary frequency control of the wind turbine based on previousresearch. First, it is determined that the virtual inertia control haslittle effect on the maximum rate of change of frequency (MaxROCOF)if the time delay of the control link of WTG is taken intoconsideration. Secondly, if a WTG operates in maximum powerpoint tracking (MPPT) mode and uses the rotor deceleration forfrequency modulation, its optimal auxiliary frequency control willcontain only droop control. Furthermore, if the droop control isproperly delayed, better system frequency response (SFR) willbe obtained. The reason is that coordination between the WTGand SG is important for SFR when the frequency modulationcapability of the WTG is limited. The frequency modulationcapability of the WTG is required to be released more ***, when designing optimal auxiliary frequency controlfor the WTG, a better control scheme is worth further study.

关键词： Frequency droop control power system frequency security rate of change of frequency(ROCOF) virtual inertia control wind turbine generator auxiliary frequency control

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simulation and feature extraction of inter-shaft bearing fault in rotor-bearing-casing system 26

Simulation and feature extraction of inter-shaft bearing fau...

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26th International Congress on Sound and Vibration, ICSV 2019

作者： Yang, Yizhou Liu, Chao Jiang, Dongxiang Han, Te State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781999181000

The inter-shaft bearing could simplify the supporting structure of a dual-rotor system, so it is widely used in rotating machinery like gas turbine engine. When monitoring the vibration of an inter-shaft bearing, sensors usually could not be installed inside the engine because of the compact structure, then will be installed on the casing. The vibration of the inter-shaft bearing will be transmitted though both the two rotors to the supporting bearings then to the casing, and both the inner and outer ring rotate, making the condition monitoring much more difficult than normal bearings. In this paper, a dual-rotor system dynamic model with the rotor-bearing-casing structure is built to simulate the vibration of an inter-shaft bearing. The rotors and the casing are modelled using finite element method and the bearings are modelled using a nonlinear multi-body dynamic model. The normal state of the inter-shaft bearing is simulated, then the bearing fault states with localized defects on the inner race, the outer race and one of the rolling elements are simulated. Signal processing methods are utilized to extract bearing fault features from the casing vibration acceleration signal. Besides the fixed rotating speed condition, rotors under variable speeds are also simulated, then the vibration signal and fault feature become more complex and the signal analysis becomes a bigger challenge © Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019. All rights reserved.

关键词： Dynamic models

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Study on lightning protection of cables and transformer in microgrid

Study on lightning protection of cables and transformer in m...

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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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Energy Internet: Concept and practice exploration

Energy Internet: Concept and practice exploration

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2017 IEEE Conference on Energy Internet and Energy System Integration, EI2 2017

作者： Cheng, Lin Qi, Ning Zhang, Fang Kong, Huichao Huang, Xuejin State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Dongguan Power Supply Guangdong Power Grid Co. Ltd Dongguan China

ISBN: (纸本)9781538614273

Under the situations of energy crisis around the world, Energy Internet has become the focus of international academic and industrial areas. In this paper, comprehensive reviews and prospects were made based on the background and current research status of Energy Internet. Moreover, the core concept, basic structure, and operation mode of Energy Internet were introduced and discussed. Finally, constructive solutions to the current problems were proposed with the demonstration project of Energy Internet that is the Beijing New Aerotropolis, which draws the future of the Energy Internet. © 2017 IEEE.

关键词： Internet of Energy

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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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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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Comparison of boost and LLC converter and active clamp isolated full-bridge boost converter for photovoltaic DC system

Comparison of boost and LLC converter and active clamp isola...

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作者： Liu, Jiye Zheng, Zedong Wang, Kui Li, Yong Dong State Key Laboratory of Control Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

DC collection network offers an attractive alternative to AC network for photovoltaic, as it avoids the charging current issues and reduces the size and weight. Variable voltage gain DC/DC converters play an important role in DC collection network. Two topologies suitable for photovoltaic DC collection are studied. Boost and LLC converter and active clamp isolated full-bridge boost converter are two converters with high and variable voltage conversion ratio suitable for the photovoltaic system. This work investigates the two converters comprehensively. The topologies are analysed so as to summarise and compare the characteristic of the converters. Soft switching condition is compared to help extend the zero voltage switching range. Voltage and current stress of the two converters are calculated. Loss comparison is made with the theoretical analysis. Advantages and disadvantages are summarised to get a deep insight into their application field. © 2019 Institution of Engineering and *** right reserved.

关键词： Topology

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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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