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International Conference on power Electronics and Motion control (IPEMC)

作者： Liqiang Yuan Zhiping Chen Xianlai Hu Junjie Ge Zhengming Zhao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781457720857

With the background park lighting application, and based on the characteristics of advanced devices in the system, this paper studies the photovoltaic (PV) light emitted diode (LED) lighting system in three main aspects, which are the design of the whole system, hybrid control strategy combining the maximum power point tracing (MPPT, for PV panels) with the energy management(for battery), and LED driving and dimming. Taking the example of an actual 50W high luminous efficacy LED system, the design, implantation and experiments are described in detail. In addition, the long-term measurement results in real environment are illustrated in this paper.

关键词： Batteries LED lamps Switches Pulse width modulation Discharges (electric)

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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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Application of Fuzzy-Rough Set theory and improved SMO algorithm in aircraft engine vibration fault diagnosis

Application of Fuzzy-Rough Set theory and improved SMO algor...

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Prognostics and system Health Management Conference (PHM)

作者： Hongzhi Xu Dongxiang Jiang Lei Liang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing China

ISBN: (纸本)9781457719097

Aircraft engine is an important component of the airplane, which lifespan and reliability have directly influence to flight safety. Vibration analysis is an effective fault diagnosis method for airplane's mechanical construction fault. Several typical vibration faults have drawn from the vibration analysis on the basis of fault mechanism in aircraft engine, and the standard vibration fault-symptom (Fuzzy Membership) relationship table have constructed based on Fuzzy Mathematic theory in this paper. Sample data are simulated on the basis of this table. Sequential Minimal Optimization (SMO) is a fast algorithm for training Support Vector Machines (SVM). The simulated result showed a great improvement on computation efficiency by selecting double threshold parameter for SMO algorithm than single threshold. In order to examine the algorithm's effect applying in the aircraft engine fault diagnosis, Radial Basis Function (RBF) Neural Network, C4.5 Decision Tree, SVM (chunking), Platt's SMO and Improved SMO algorithm are applied to the training data and test data. It is shown that the Improved SMO algorithm displayed superior comprehensive performance. Finally, the vibration fault feature is reduced based on Fuzzy-Rough Sets theory. The research shows that the Improved SMO algorithm is quicker than other algorithm in aircraft engine fault diagnosis with the reduced feature attributes, and its accuracy is high.

关键词： Vibrations Accuracy Safety Aircraft Classification algorithms Support vector machines

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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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A neutral-point potential balancing algorithm for five-level ANPC converters

A neutral-point potential balancing algorithm for five-level...

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2011 International Conference on Electrical Machines and systems, ICEMS 2011

作者： Wang, Kui Li, Yongdong Zheng, Zedong State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457710445

Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point clamped (NPC) converters and flying-capacitor (FC) converters. Its dc-link is subdivided into two equal parts and the main problem is the neutral-point (NP) potential balancing. In this paper, a NP potential balancing algorithm based on zero-sequence voltage injection is presented. By calculating the NP currents of all key zero-sequence voltages, the most appropriate zero-sequence voltage is selected to generate the demanded NP current. Moreover, by further limiting the span of injected zero-sequence voltages, the NP balancing algorithm can make the two IGBTs connected in series operate at fundamental frequency. A three-phase five-level ANPC inverter prototype was built up and experimental results are presented to verify the validity of this algorithm. © 2011 IEEE.

关键词： power converters

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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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Electric Ship Technologies Symposium

作者： Gong, Yuan Chen, Laijun Chen, Ying Xu, Yin State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781424492725

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. © 2011 IEEE.

关键词： Simulators

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