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IEEE General Meeting power& Energy Society

作者： Hui-fen Chen Ying Qiao Zong-xiang Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781467327275

This paper studies a combined voltage control strategy that coordinates a variety of reactive compensative devices such as fixed capacitors, SVC/Statcom, DFIGs (Double-fed Induction Generators) to improve voltage control performance in multi-time scale. Based on the control restraints and response performance, three modes - planning mode, online mode and emergency mode - are optimized for lower cost and higher security margin, respectively. The paper introduces wind power forecast into wind farm voltage planning for slow, discrete devices such as fixed capacitor, while engages devices that are capable of instantaneous response to smooth quick, small voltage fluctuation and track online voltage reference from dispatching centre. The feasibility, effectiveness and superiority of the proposed control strategy are verified with simulation.

关键词： Wind farms Reactive power Automatic voltage control Security Capacitors Static VAr compensators

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Investigation of bipolar block emergency in UHVDC convertor station caused by lightning stroke

Investigation of bipolar block emergency in UHVDC convertor ...

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2012 31st International Conference on Lightning Protection, ICLP 2012

作者： Zhang, Xiao Yu, Zhanqing He, Jinliang Luo, Bin Cai, Hansheng State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Xipeng Chen Technology Research Centre China Southern Power Grid Co. Ltd Guangzhou Guangdong Province China

ISBN: (纸本)9781467318976

It is noteworthy that bipolar block emergencies of the ±800kV UHVDC system in China happened twice within two years caused by lightning strokes. To recur and investigate the mechanism of such emergencies, lightning transient performance and relative electromagnetic interference (EMI) in the UHVDC system are investigated. Wide-band circuit models of major UHVDC equipments are set for calculation, while the lightning stroke shielding failure process and transmission corona loss are also considered during the simulation. By combining the fault records in the converter station and simulation results , possible ways of EMI into the secondary system produced by primary circuit lightning transient are analyzed. The results would help explain the cause of such bipolar block emergency and provide reference for protection methods of lightning caused EMI in UHVDC system. © 2012 IEEE.

关键词： Lightning

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A novel hybrid-clamped four-level converter

A novel hybrid-clamped four-level converter

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Annual IEEE Conference on Applied power Electronics Conference and Exposition (APEC)

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

A novel hybrid-clamped four-level inverter topology is proposed in this paper. Only two active switches and a floating capacitor are required as clamping devices per phase leg. The DC-link of this topology is subdivided into three parts and the voltage balancing of DC-link capacitors and floating capacitors can be achieved by selecting proper redundant switching states. The operating principle and voltage balancing method of this converter are introduced in details. simulation and experimental results are presented to confirm the validity of this topology.

关键词： Capacitors Switches Voltage control Topology Clamps Integrated circuit modeling Electric potential

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A compact coaxial gas filled switch

A compact coaxial gas filled switch

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IEEE International Conference on Plasma Science (ICOPS)

作者： Xiaobing Zou Xinjing Cai Xinxin Wang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China College of Electrical Engineering Northeast Dianli University Jilin China

Summary form only given. As we know, the risetime of the output voltage of a pulse power generator is mainly determined by the performance of the main discharge switch. Recently, to calibrate nanosecond pulse voltage dividers, A nanosecond pulse generator with an output voltage of 2–10 kV was constructed. The generator was composed of a DC charging source, a 50 Ohm coaxial cable as a pulse forming line (PFL), a self-breakdown coaxial gas filled switch, a 50 Ohm coaxial cable as pulse transmission line (PTL), and a matched load. The gas filled switch with two plate electrodes was made as compact as possible to reduce the switch inductance. The gap distance of the switch is fixed to be ∼0.5mm and filled with pressurized nitrogen gas. Extensive tests were made to measure the risetime of the output voltage as the filled gas pressure changed from 0.1MPa ∼0.6Mpa. the averaged risetime of the output voltage is ∼14 ns as the switch gas pressure is set to be 0.1MPa, while the risetime is ∼1.5 ns as the gas pressure increased to 0.6MPa. A CCD camera was used to take pictures of the discharge arc between the main electrodes. As the gas pressre is ∼0.1Mpa, only one single discharge channel was observed. While the gas pressure is above 0.5Mpa, the switch usually breaks down in multi-channel mode, which would result in a low switch inductance and a faster risetime of the output voltage.

关键词： Switches Educational institutions Discharges (electric) Voltage measurement Switching circuits Electrical engineering Generators

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Evolution of the exploding titanium wire in 5-50 kPa ambient gas

Evolution of the exploding titanium wire in 5-50 kPa ambient...

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IEEE International Conference on Plasma Science (ICOPS)

作者： Xiaobing Zou Zhiguo Mao Xinxin Wang Weihua Jiang Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Department of Physics and Chemistry College of Physics North China University of Technology Beijing China

Experiments of electrical wire explosions (EEW) for nano-powder production were performed on a small-scale pulsed power device, which consists of a low-inductance capacitor bank of 2-4 μF typically charged to 8-25 kV. Titanium wires, 85 mm in length and 175 μm in diameter, were installed inside a discharge chamber filled with 5-50 kPa air. The peak discharge current is about 8-20kA with a rise time of 6 μs. We investigated the evolution of the exploding titanium wire with a Mach-Zehnder interferometer. From the time sequence of the interferograms, we found that two different modes of wire explosion exist, depending on the ambient gas pressure. As the gas pressure is in the range of 5-20 kPa, more than one vapor burst was observed, which we called multi-burst mode. While the gas pressure is above 40 kPa, the whole wire would explode totally within one single vapor burst, which we called one-burst mode. Based on the calculated deposition energy of the exploding wire and the gas discharge theory, we explained the relationship between the exploding modes and the ambient gas pressure.

关键词： Wires Titanium Educational institutions Discharges (electric) Physics Explosions Electrical engineering

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IMPACT OF THE LOCATION OF DISCHARGE SOURCE ON THE PD SIGNAL IN GIS

IMPACT OF THE LOCATION OF DISCHARGE SOURCE ON THE PD SIGNAL ...

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The ⅪⅩ International Conference on Gas Discharges and Their Applications

作者： DENGWEI DING WENSHENG GAO WEIDONG LIU RUI FENG State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua University

ISBN: (纸本)9771003651221

In order to monitor the on-line condition of GIS and diagnose existing defects,the ultra high frequency(UHF) methods are widely used for detecting partial discharge(PD) owing to its sensitivity and anti-interference *** partial discharge will happen when the electric field is non-uniform because of the defects in *** location of the partial discharge source has an impact on electromagnetic wave generated from the *** the PD detection,the UHF signal acquired by the coupler in GIS is produced by the change in the electric field,so the characteristics of the signal are related with the position of the *** this paper,the distance between the PD source and the inner conductor of GIS is changed;the amplitude of time-domain signal and the frequency spectrum of the UHF signal are *** is discovered that the amplitude of time-domain signal is various with the distance between the defect and the inner conductor,as well as the frequency *** that, the mode of UHF signal in GIS is affected by the location of PD,the component of TEM mode and high order mode(TE mode and TM mode) change with the distance between the PD source and the inner conductor.

关键词： domain IMPACT OF THE LOCATION OF DISCHARGE SOURCE ON THE PD SIGNAL IN GIS

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Effects of manganese dioxide additives on the electrical characteristics of Al-doped ZnO varistors

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Science China(Technological Sciences) 2011年第8期54卷 2204-2208页

作者： LONG WangCheng HU Jun HE JinLiang LIU Jun ZENG Rong State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

The effects of manganese dioxide (MnO 2 ) additives on the electrical characteristics of the Al-doped ZnO varistors are investigated. The leakage current densities of the samples decrease first and then increase again with the increase of the amount of MnO 2 additives. Correspondingly, the nonlinear coefficients of the samples keep on increasing and then decrease. In addition, the donor densities increase monotonously with the amount of the doped MnO 2 increasing. The effects of MnO 2 additives on the electrical characteristics of the samples are different from the conclusion of previous literatures. The reasons of the distinct effects are supposed to be related with the donor and interface state densities of the samples.

关键词： ZnO varistots manganese dioxide electrical characteristics low residual voltage ratio simulation

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Synergistic utilization of coal and other energy- Key to low carbon economy

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能源前沿 2011年第1期5卷 1-19页

作者： Weidou NI Zhen CHEN State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal EngineeringTsinghua UniversityBeijing 100084China

In China, coal is a dominant component of energy mix, and it is expected to remain as such over the next 30 to 40 years. Coal is expected to be used even more in power generation. The direct combustion of coal already has been causing severe pollution and ecological degradation, and it is quite difficult to address the need to reduce greenhouse gas (GHG) given the direct combustion of coal. Therefore, the polygeneration system based on coal gasification, which is one of the major examples of synergistic utilization of coal, is proposed. It is a comprehensive solution to meet the energy challenges China is facing. Furthermore, the synergy of fossil fuels (especially coal) with renewable energy, the synergy of different kinds of energy for energy storage, the synergy of centralized and distributed supply of different kinds of energy, and the synergy of different kinds of energy in smart energy grid (power, gas, heat, and water) are the keys to making China a low-carbon economy. Carbon dioxide (CO2) mitigation in China should begin from the coalchemical industry given their accumulated relevant experiences. The mitigation process should gradually be transformed into the 'IGCC + polygeneration + CCUS'.The objectives of this paper are to describe the synergistic utilization of coal, and to analyze the synergy of coal with other energy resources, and to propose the scientific and technological problems to achieve these synergies.

关键词： synergy clean and efficient utilization of coal coal-based polygenration CO2 mitigation energy storage

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Design and implement of an active damping LCL-filter for three-level voltage source PWM rectifier

Design and implement of an active damping LCL-filter for thr...

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2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Liu, Chao Zhao, Zhengming Lu, Ting Yuan, Liqiang 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

Grid-connected LCL filter of voltage source PWM rectifier (VSR) can not only reduce the values of inductance, improve the system dynamic response, but also reduce the cost. However, LCL filter brings stability problem if no damping method is adopted. In order to guarantee the stability and high power factor of VSR at the same time, active damping control method rather than reactive damping method is required. Nowadays, the study on LCL filter is just for two-level VSR. In this paper, parameter design and damping method are being placed in three-level VSR for widely use. For a three-level PWM rectifier, a new parameter design method as well as active damping method is proposed and verified by Matlab-Simulink simulation and experiment. © 2011 IEEE.

关键词： Damping

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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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