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作者： Xinghua, Tao Yongdong, Li Min, Sun State Key Lab of Control and Simulation of Power System and Generation Equipments Dept. of Electrical Engineering Tsinghua University China Dept. of Electrical Engineering Naval Engineering University China

ISBN: (纸本)9788986510119

Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue in CHBR. To satisfy the demand of rectifier such as unity power factor and regulated output DC voltages, the proposed control scheme consists of two parts. One is for shaping the grid current waveform and regulating the sum of DC-link voltages of all the cells;the other one is for balancing DC-link voltages. The latter is more concerned in this paper and is discussed in detail especially. simulations and experiments are carried on. The results verified the feasibility and effectiveness of the proposed scheme.

关键词： Electric rectifiers

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A phase-disposition PWM method for DC voltage balance in cascaded h-bridge rectifier

A phase-disposition PWM method for DC voltage balance in cas...

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作者： Tao, Xinghua Li, Yongdong Sun, Min State Key Lab of Control and Simulation of Power System and Generation Equipments Dept. of Electrical Engineering Tsinghua University China Dept. of Electrical Engineering Naval Engineering University China

ISBN: (纸本)9788986510119

In this paper, a novel control scheme for cascaded H-Bridge rectifier (CHBR), which can be used as the primary end of high voltage high power multilevel converters, is presented. The controller is similar with the one for single phase rectifier. To improve the performance of the controller, notch filter and proportion resonance (PR) controller are employed and the discrete methods for them are discussed in detail. The different function of CHBR controller from the single rectifier is for voltage balancing. Therefore, the phase-disposition technology, which is used in the multilevel converter, is introduced to eliminate the voltage error from the expected value. With this approach, the states of the switches of the CHBR are decided correctly by the practical condition and then the DC-link capacitors of the cells are controlled to charge or discharge in the way which results to voltage balancing. The effectiveness of the proposed approach is verified by experimental results.

关键词： controllers

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Dynamic emergency control in digital distribution substation with MW PV power

Dynamic emergency control in digital distribution substation...

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2010 5th International Conference on Critical Infrastructure, CRIS 2010

作者： Wang, Bin Huang, Tianxiao Dong, Xinzhou Jiang, Bo Bo, Z.Q. Dept. of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China AREVA T and D UK Ltd. Stafford STl7 4LX United Kingdom

ISBN: (纸本)9781424480814

MW level photovoltaic generation has enough power to support the partial loads in the island operations. But the challenge is how to balance the power supply and load while the power grid is blackout, and the power supply changes to PV power. In response to this question, the anti-islanding strategy is replaced by balancing the PV output and the load shedding in paper to achieve the available maximum power balance in distribution substation. It is achieved by collecting all feeders currents (power supply and feeder outputs), which is realized in the digital substation based on IEC61850. The system scheme and the dynamic emergency control strategy to inverters in PV controller are introduced in paper. The work of the paper is valued to the research on the novel dynamic control scheme in distribution system with DGs. © 2010 IEEE.

关键词： Electric power transmission networks

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DC pre-excitation application in three-phase induction motor drive system

DC pre-excitation application in three-phase induction motor...

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IEEE International Symposium on power Electronics for Distributed generation systems (PEDG)

作者： Sideng Hu Zhengming Zhao Ting Lu Liqiang Yuan Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Due to the current restriction of semiconductor devices, the start-up is an extremely important process in the ASD (adjustable speed drive) system. DC pre-excitation is one of the effective solutions for increasing the starting torque and depressing the starting inrush current. However the effect of DC pre-excitation would be discounted if it could not be compatible with the induction motor drive control system. Also the stability of the DC pre-excitation application is related to its operational mode. This paper addresses the principle of DC pre-excitation and excavates its relationship with current control. The method to improve the stability of DC pre-excitation effectively shielding EMI is detailed. The relevant study has been implemented in a control system for a 55 kW and 160 kW induction motor and the simulation and experimental results validate the effectiveness of the proposed design method.

关键词： Induction motors Torque DC motors Electromagnetic interference Process control Variable speed drives Switches

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Approaches to enhance discrete control algorithms serving for motor drive system

Approaches to enhance discrete control algorithms serving fo...

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IEEE Energy Conversion Congress and Exposition, ECCE

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

The discrete control technology for AC machine drives is widely applied in the industrial field. This paper aims to excavate new approaches to enhance the discrete control system in AC motor drive systems from following aspects: matching design for discrete subsystems, synchronization in the signal processing and dealing with the restrictions in the voltage output. The proposed approaches are incorporated with three key techniques applied in high performance induction motor drive systems: DC pre-excitation, parameter identification and flux observer with a sensorless control to verify the feasibility. The anti-interference and synchronization procedure in the implementation are also proposed. The experimental results from the test on 55kW/400V and 160kW/400V ASD (Adjustable Speed Drives) systems validate the effectiveness of the proposed approaches.

关键词： Switches Variable speed drives Observers Parameter estimation Pulse width modulation Induction motors

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simulation of lightning strike in 2-D and 3-D with fractal theory and its application

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2010年第22期30卷 127-134页

作者： Xu, Wei Chen, Shui-Ming He, Jin-Liang State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

Lighting causes great damage to power systems due to the stochastic nature of lightning discharges and the vulnerability of lightning leaders to various environments in the process of inception and propagation. In this work, the growth of diffusion limited aggregation (DLA) was adopted for reproducing branches and tortuosity of lightning channels in both 2-D and 3-D simulations. By comparing the fractal dimensions of natural lightning discharges and simulation results on various discharge settings, we discovered that a fractal coefficient η = 2 can deliver a credible model of lightning strikes. We further proved the consistency between simulation results and observations conducted in Japan during 2005 and 2006 winter seasons on lightning strikes to a windmill and its lightning-protection tower. But the credibility of the result needs to be verified by further experimental data, when the model extended from 2-D to 3-D. Moreover, striking probability and the shielding effect in the actual condition were analyzed with the proposed simulation model. © 2010 Chin. Soc. for Elec. Eng.

关键词： Fractal dimension

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Design and implementation of the high efficiency photovoltaic system with solid state lighting

Design and implementation of the high efficiency photovoltai...

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International Conference on Electrical Machines and systems (ICEMS)

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

Photovoltaic application of LED lighting has been a hot trend in residential illumination, for it integrates the advantages of both the PV systems and LED lights. However, it has a series of problems, such as high thermal loss, poor reliability, and a short life span. To address these problems, this paper presents a deep research on the whole system from a low-cost, high-efficiency and long-life point of view. A main circuit integrating maximum power point tracing (MPPT) control and battery management, as well as a double-loop control for LED load is developed. A set of protection system is applied to ensure high reliability of the system. The control strategies are tested on the demonstrator and prove to be effective.

关键词： Light emitting diodes Batteries Discharges MOSFET circuits Lighting Photovoltaic systems Snubbers

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A Review on Overvoltages in Microgrid

A Review on Overvoltages in Microgrid

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Shuiming Chen Hongqiao Yu Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Now microgrid has aroused increasing attention due to energy sustainable development and the development of distributed generations (DG), such as micro-turbines, gas turbines, wind power, photovoltaic and fuel cells. This paper introduces the basic structure of microgrid and summarizes the overvoltages that can occur in microgrid, including ground fault overvoltages, resonant overvoltages, overvoltage related to voltage regulation, switching overvoltages of inner microgrid, transfer overvoltages from distribution network (such as lightning and switching overvoltages). By analysis, this paper obtains the following conclusion: resonant overvoltages and lightning stroke transfer overvoltages are the most serious for microgrid.

关键词： Surges Resonance Lightning Sustainable development Distributed control Wind turbines Wind energy Photovoltaic systems Solar power generation Fuel cells

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Predictive DC voltage control for three-phase grid-connected PV inverters based on energy balance modeling

Predictive DC voltage control for three-phase grid-connected...

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IEEE International Symposium on power Electronics for Distributed generation systems (PEDG)

作者： Fanbo He Zhengming Zhao Ting Lu Liqiang Yuan State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

DC voltage control is critical for grid-connected inverters, as it contributes to reduce the DC capacitance and improve system reliability as well as MPPT performance. A predictive control scheme of DC voltage for single-stage three-phase grid-connected PV inverters is proposed based on the analysis of the energy balance relationship in one control period, while AC current is also regulated by predictive control. The proposed scheme provides both good dynamic and steady-state performance. The dynamic response is especially excellent. The DC voltage is adjusted as fast as possible with little overshoot.

关键词： Voltage control Inverters Voltage measurement Regulators Predictive control Steady-state Capacitance

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A phase-disposition PWM method for DC voltage balance in cascaded h-bridge rectifier

A phase-disposition PWM method for DC voltage balance in cas...

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2010 International Conference on Electrical Machines and systems, ICEMS2010

关键词： Cascaded H-bridge rectifier Phase-disposition PWM PR controller Voltage balance

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