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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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Air-gap magnetic field distribution and inductance characteristics in a long primary sectional powered variable pole pitch linear induction motor

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Qinghua Daxue Xuebao/Journal of Tsinghua University 2014年第9期54卷 1161-1165and1172页

作者： Mu, Shujun Chai, Jianyun Sun, Xudong Wang, Shanming State Key Lab. of Security Control and Simulation of Power Systems and Large Scale Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China

This study investigated the air-gap magnetic field distribution and inductance characteristics of a long primary sectional powered variable pole pitch linear induction motor (VPPLIM). A one-dimensional analytical model and a 2-D finite element model were used to analyze the air-gap magnetic field distribution in the VPPLIM with harmonic fields for uniformly accelerating the mover with a typical AC supply. The air-gap magnetic field distribution was used to develop analytical expressions for the self-and mutual-inductances of the motor and their characteristics. The analytical expressions are verified by the finite element simulations. ©, 2014, Press of Tsinghua University. All right reserved.

关键词： Inductance

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Preventive control for combined heat and power system: A day-ahead security constrained economic dispatch model

Preventive control for combined heat and power system: A day...

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The 11th IET International Conference on Advances in power System control, Operation and Management (APSCOM 2018)

作者： Qunli Lin Xinwei Shen Yinliang Xu Yong Sun Zhenyuan Li Qinglai Guo Hongbin Sun Shenzhen Environmental Science and New Energy Technology Engineering Laboratory Tsinghua-Berkeley Shenzhen Institute Tsinghua University Shenzhen China Jilin Power Grid Company State Grid Corp. of China Jilin China State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (数字)9781839530043

Integrated Energy System (IES), which plays a vital role in the development of Energy Internet (EI), can improve the efficiency of energy utilization and integration of renewable energy. However, the coupling between multiple energy systems will bring new challenges to the security control of the IES, such as combined heat and power (CHP) system. For IES, the preventive control is the first line of defense to ensure that the system can keep stable operation when contingencies such as the transmission outage or generator outage happen. This paper proposes a preventive control approach for CHP system, in which a day-ahead security constrained economic dispatch (SCED) model of CHP system considering the coupling of heat and electric is formulated. The model aims to minimize the cost of the whole system, while the preventive control of the system can be achieved with the constraints considering the normal states and contingencies states. Case studies based on the IEEE 9-bus system with CHPs are presented to illustrate the approach. The case result shows that the combined electric and heat optimal dispatch is more economical than when two systems are independently optimized and operated. And the proposed preventive control approach of the CHP system can satisfy both the electric and heat demand, and system security is ensured when the N-1 contingencies happened.

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Research on measuring magnetic field around 10kV cable based on three-split magnetic core

Research on measuring magnetic field around 10kV cable based...

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Energy, Electrical and power Engineering (CEEPE), International Conference on

作者： Zhe Hou Sen Teng Wenqiang Dang Xiahaoyue Yun Zeli Ju Yang You Zixiong Cai Power Equipment Condition Assessment Center State Grid Shaanxi Electric Power Research Institute Xi’an China Power Distribution Network Department State Grid Shaanxi Electric Power Company Xi’an China Chongqing Key Laboratory of Complex Systems and Bionic Control Chongqing University of Posts and Telecommunications Chongqing China

ISBN: (数字)9798350375794

ISBN: (纸本)9798350375800

The utilization of 10kV cable in urban distribution networks and industrial settings necessitates regular maintenance and fault detection to guarantee uninterrupted power supply. Ensuring the de-energization of inspected cables on-site is crucial for operator safety, yet current methods for evaluating the energization status of 10kV cables lack effectiveness. This study introduces an electromagnetic detection sensor utilizing a three-split magnetic core design, aimed at addressing the issue of zero magnetic field integral resulting from the three-phase current vector sum of 0 in a 10kV cable. This study employs theoretical analysis and finite element simulation to investigate the magnetic induction state of a three-split magnetic core surrounding a 10kV distribution cable. The findings confirm that the three-split magnetic core is capable of detecting the magnetic field generated by the current load in the phase conductor on the outer surface of the 10kV cable. These results offer theoretical justification for further research into live state detection technology for 10kV cables utilizing the three-split magnetic core.

关键词： Magnetic flux density Sensitivity power cables Magnetic cores Solids Vectors Finite element analysis

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A Corrective Security-Constrained Optimal power Flow Method for AC/DC Hybrid systems Based on MMC-HVDC

A Corrective Security-Constrained Optimal Power Flow Method ...

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IEEE Conference on Energy Internet and Energy System Integration

作者： Yi Lin Yu-chen Tang Liu-qing Qiu Ming-ye Zhang Yu-tao Ju State Grid Fujian Power Economic Research Institute State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University College of Information and Electrical Engineering China Agricultural University

ISBN: (纸本)9781538614280

This paper presents an optimal power flow (OPF) model for AC/DC meshed networks with Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) system. The OPF problem is formulated to minimize the total network loss of the whole AC/DC grids by adjusting generators and modular multilevel converters considering N-1 constraints and post-contingency corrective control. A practical method is proposed to handle N-1 static security constraints and corrective control with OPF more effectively. simulations are conducted on IEEE 39-bus testing system and a practical power grid. The results demonstrate the effectiveness of the approach.

关键词： Modular Multilevel Converter HVDC Optimal power flow Interior point method N-1 static security constraints Corrective control

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Transient stability assessment based on 2D combined attribute decision tree

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第SUPPL. 1期29卷 17-24页

作者： Wang, Kang Sun, Hong-Bin Zhang, Bo-Ming Wu, Wen-Chuan Jiang, Wei-Yong State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

A method for the power system transient stability assessment based on 2D combined attribute decision tree was proposed. Different from single attribute decision trees, the 2D trees combine two attributes as one automatically to improve its classifying ability in case of multi-dimension and nonlinear border among classes. In the proposed 2D tree, Gini coefficient based 2D combined splitting criterions was adopted and search method for splitting line in an inverse direction was developed. Case study was carried out in one-machine infinite bus system, IEEE 39-bus system and a real provincial system. Results show that, 2D combined attribute decision trees generated by the proposed method are smaller in structure, have the higher accuracy and generalization ability than that generated by the single attribute decision trees. Meanwhile, some important relationship between physical variables in power systems can be mined by the proposed method. Advantages mentioned above make that the proposed method is potential for real-life power system applications. © 2009 Chin. Soc. for Elec. Eng.

关键词： Decision trees

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Enhancing N-1 Security via Building Thermostatic Load control Strategy

Enhancing N-1 Security via Building Thermostatic Load Contro...

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International Conference on the European Energy Market

作者： Xin Jia Haiwang Zhong Qing Xia Molin Huo Xingyang Zhu Chongqing Kang Department of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China State Grid (Suzhou) City & Energy Research Institute Jiangsu China

With the increase of distributed energy resources (DER), energy network's uncertainty is growing continuously, and grid operations is encountering severe challenges. Conventionally, the N-1 security criteria is satisfied mainly via adjusting generators' output. But in some cases, it is not effective because of the complex network constraints and the generators' limited dispatch range. With the development of smart buildings, there are lots of thermostatic controlled loads inside the buildings. The flexibility of building energy consumption is underutilized in the past. Therefore, a new method is proposed in this paper to enhance N-1 security via building thermostatic load control. A three-stage model is formulated. An energy-consumption simulation software termed EnergyPlus is utilized to calculate the relationship between indoor temperature settings and thermostatic loads of buildings. Case studies based on the modified IEEE-30 bus system with building thermostatic load validate the effectiveness of the proposed control method.

关键词： EnergyPlus N-1 security Smart building Thermostatic load Three-stage model

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Intrinsic Insight of Energy-Efficiency Optimization for Co2 Capture by Amine-Based Solvent: Effect of Mass Transfer and Solvent Regeneration

SSRN

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SSRN 2022年

作者： Chen, Zhen Yuan, Bingling Zhan, Guoxiong Li, Yuchen Wang, Lidong You, Changfu Li, Junhua State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China Key Laboratory for Thermal Science and Power Engineering the Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing100084 China MOE Key Laboratory of Resources and Environmental Systems Optimization Department of Environmental Science and Engineering North China Electric Power University Beijing102206 China

Here the energy-efficiency performance of CO2 capture is investigated based on bench-scale continuous absorption-desorption system. A comprehensive evaluation is performed by L25(65) orthogonal tests to analyze the effects of operating conditions on CO2 capture. With combination of Eulerian-Eulerian method with the population balance model, we predict the dynamics evolution process of dispersed bubble, in order to provide the detailed information of interphase contact area and multiphase flow for modelling complete mass transfer parameters. Meanwhile, rigorous process simulation is developed to analyze the energy consumption of carbon capture. Experiments reveal desorption temperature and flue gas flow play a major role for CO2 capture efficiency. Rising flue gas flow could promote interfacial area, but decreases contact time, overally, net CO2 flow approximately determines the linear relationship of capture efficiency and absorption rate. Higher desorption temperature provides leaner solvent to drive CO2 absorption, but consumes greater energy penalty for CO2 capture. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

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Gas generation Characteristics of Transformer oil under Combined AC-DC Voltages in the Process of Arcing

Gas Generation Characteristics of Transformer oil under Comb...

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Annual Report Conference on Electrical Insulation and Dielectric Phenomena

作者： Y.X. Zhou Y.C. Sha X.X. Jiang Q.H. Sun Y.S. Wang J.H. Tian State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing China

ISBN: (纸本)9781457709852

As an important equipment, convertor transformer plays a crucial role in ultra high voltage direct current (UHVDC). How to improve the safety running level of convertor transformers is a key problem to be solved imminently. Compared with AC power transformers, the valve side windings of convertor transformers will endure combined AC-DC voltage. In these conditions, the gas generation characteristics in oil for convertor transformers will be more complicated. In this paper, according to the operational principle of convertor transformers, the ratios between AC and DC voltage on valve side windings in the star connection and triangular connection were 77.1% and 83.7% respectively. Based on the above results, 65 kV peak voltages in 5 different AC and DC voltage forms were applied to the needle-plate electrode model for 2 hours. The discharge current and voltage waveforms were recorded and the arc current pulses had a short lasting time about 1.2 ms. Then the mean discharge energy was calculated at 0.1 to 0.3 J. At the same time, the gas generation characteristics under combined AC-DC voltage were obtained by using the gas chromatographic analysis method. The variations of amounts and generation rates of characteristic gases were measured with time during 2 hours, which provided fault judgment criterions and experimental experience. The experimental results showed that the amounts and generation rates of H2, C2H2 and total hydrocarbon under the pure DC voltage or combined AC-DC voltage were more than those under the pure AC voltage. It might illustrate the fact that effects of different voltage forms would lead to different gas generation characteristics could not be ignored.

关键词： Combined AC-DC voltage Needle-plate electrode model Gas generation Characteristics

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Fault diagnosis of direct-drive wind turbine based on support vector machine

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Journal of Physics: Conference Series 2011年第1期305卷

作者： X L An D X Jiang S H Li J Chen State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

A fault diagnosis method of direct-drive wind turbine based on support vector machine (SVM) and feature selection is presented. The time-domain feature parameters of main shaft vibration signal in the horizontal and vertical directions are considered in the method. Firstly, in laboratory scale five experiments of direct-drive wind turbine with normal condition, wind wheel mass imbalance fault, wind wheel aerodynamic imbalance fault, yaw fault and blade airfoil change fault are carried out. The features of five experiments are analyzed. Secondly, the sensitive time-domain feature parameters in the horizontal and vertical directions of vibration signal in the five conditions are selected and used as feature samples. By training, the mapping relation between feature parameters and fault types are established in SVM model. Finally, the performance of the proposed method is verified through experimental data. The results show that the proposed method is effective in identifying the fault of wind turbine. It has good classification ability and robustness to diagnose the fault of direct-drive wind turbine.

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