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Sixth International Conference on power Electronics and Drive systems, PEDS 2005

作者： Guo, Wei Zhao, Zhengmlng Department of Electrical Engineering Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Beijing China

ISBN: (纸本)0780392965

Two axially-laminated Glued Axially-Laminated Synchronous Reluctance Permanent Magnetic (SR-PM) motors are designed and tested. Compared to general Axially-Laminated Synchronous Reluctance (SR) motors, the steel bracket is replaced with iron lamination for reduction of iron loss in rotor. The axially-laminated Iron and magnet are glued on the bracket with high strength cement with the help of special clamping device. Then the rotor Is grinded to the cylinder and a stainless steel rotor sleeve is added to enhance the strength. The design flow starts with initial sizes trade-off and static performance analysis followed by high speed performance validation and dynamic operation simulations. The electromagnetic parameters measurement, no-load and load test are carried out on test bed to verify the design. The comparison of these two sample motors are given for future design reference. It can be concluded that very poor max energy product PM material is not a good choice for application that requires high power density. © 2005 IEEE.

关键词： Reluctance motors

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Adaptive deblock for DC line fault in full bridge sub-module based MMC-HVDC system 15

Adaptive deblock for DC line fault in full bridge sub-module...

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15th International Conference on Developments in power System Protection, DPSP 2020

作者： Cai, Jing Dong, Xinzhou State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781713827894

Modular multilevel converter based high voltage direct current (MMC-HVDC) transmission technology has been widely applied in power systems, such as AC systems interconnection and renewable energy access, due to its superiorities. The long distance and complex operation environment lead to high probability of DC transmission line faults. Inevitable faults will interrupt normal power transmission and may cause severe accidents without appropriate faults handling scheme in both HVDC and AC/DC hybrid systems. MMC-HVDC utilizing submodules with fault clearing ability, such as Full-Bridge-Submodule (FBSM), can reduce fault current rapidly through blocking all submodules and attempt to resume power transmission by deblocking after waiting for deionization time. But the deblock operation is blind, which may aggravate outrage consequences with producing extra impacts on system and extending fault handling time in case of permanent faults. In order to realize ideal fault handling, which means submodules only deblock under temporary fault while cut off the fault line in case of permanent fault, an adaptive deblock strategy is proposed in FBSM based MMC-HVDC system mainly through distinguishing two fault states. A simulation model is established in PSCAD/EMTDC to verify feasibility and effectiveness of proposed scheme. Applicability to other submodules with fault clearing capability also been analysed. © 2020 IET Conference Publications.

关键词： Renewable energy resources

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Iron loss evaluation and comparison in application of reduced common mode voltage PWM methods 7

Iron loss evaluation and comparison in application of reduce...

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7th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2015

作者： Liu, Fang Lu, Ting Zhao, Zhengming Gu, Qing Yuan, Liqiang Li, Kai State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781467371506

The application of reduced common mode voltage pulse width modulation methods bring much high order harmonics to the variable speed drive system, which causes considerable iron loss inside the electric motor. In this paper, an improved iron loss model considering those high order harmonics is proposed. Iron loss coefficients are obtained based on experimental data by utilizing multiple linear regression and harmonics analysis method. Comparisons of the iron losses between various PWM methods are made for both experimental results and calculated results. It is found that by utilizing RCMV PWM methods, the iron loss of the induction motor becomes larger. The differential values of iron losses between RCMV PWM and CPWM decrease with the increase of the modulation ratio as a result of the reduction of zero space vectors' action time. © 2015 IEEE.

关键词： Pulse width modulation

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Design and implementation of the compact main circuit of IGBT-based converter

Design and implementation of the compact main circuit of IGB...

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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Wang, Xuesong Zhao, Zhengming Yuan, Liqiang Zhang, Yingchao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781424418497

The compact main circuit has many advantages, such as reducing volume and weight, saving costs and convenient for transportation. This paper presents three key problems including switching power supply, sampling and protection system, and cooling system. Through simplifying circuit and optimizing device parameters, the switching power supply can provide multiplex regulated power supplies with 540 VDC input directly. A simple circuit based on ripple principle can detect missing phase of input fault easily. The heat sink can be designed in a small volume through selecting suitable cooling fans, reducing switching frequency and setting minimum pulse width. A 15kW converter has been designed and implemented based on the above. Furthermore, this main circuit has been proved by practical application and long-term reliable operation. © 2008 IEEE.

关键词： Cooling systems

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Flexible unbalanced control with peak current limitation for virtual synchronous generator under voltage sags

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Journal of Modern power systems and Clean Energy 2018年第1期6卷 61-72页

作者： Tianwen ZHENG Laijun CHEN Yan GUO Shengwei MEI State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Qinghai Key Lab of Efficient Utilization of Clean Energy New Energy Photovoltaic Industry Research Center Qinghai University

Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage *** overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is *** on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive *** the injected currents are kept within safety values for a better utilization of the VSG power ***,the experimental platform is *** results demonstrate the validness and effectiveness of the proposed control strategy.

关键词： Virtual synchronous generator Unbalanced control Current reference generator power reference generator Voltage sags

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Nanopowder production by gas-embedded electrical explosion of wire

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Chinese Physics B 2013年第4期22卷 350-353页

作者：邹晓兵毛志国王新新江伟华 State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Department of Physics and Chemistry College of Science North China University of Technology

A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and a production chamber housing the exploding wire load and ambient gas. With the EEW device, nanosize powders of titanium oxides, titanium nitrides, copper oxides, and zinc oxides are successfully synthesized. The average particle size of synthesized powders under different experimental conditions is in a range of 20nm–80nm. The pressure of ambient gas or wire vapor can strongly affect the average particle size. The lower the pressure, the smaller the particle size is. For wire material with relatively high resistivity, such as titanium, whose deposited energy Wd is often less than sublimation energy W s due to the flashover breakdown along the wire prematurely ending the Joule heating process, the synthesized particle size of titanium oxides or titanium nitrides increases with overheat coefficient k （k = W d /Ws ） increasing.

关键词： electrical explosion of wire nanosized powders particle size

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Design and implementation of photovoltaic lighting system with high luminous efficacy LEDs

Design and implementation of photovoltaic lighting system wi...

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2012 IEEE 7th International power Electronics and Motion control Conference - ECCE Asia, IPEMC 2012

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

ISBN: (纸本)9781457720864

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. © 2012 IEEE.

关键词： Solar panels

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Fault current suppression for MMC-MTDC with the resistive type superconducting fault current limiter

Fault current suppression for MMC-MTDC with the resistive ty...

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2021 Annual Meeting of CSEE Study Committee of HVDC and power Electronics, HVDC 2021

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

ISBN: (纸本)9781839537035

With effective properties, a resistive-type superconducting fault current limit (R-SFCL) has become an effective device to restrain DC-side bipolar short fault currents in multilevel modular converter multiterminal DC systems (MMC-MTDCs). However, due to the resistance-energy accumulation-dependent characteristics of the R-SFCL device, the fault durations and different fault current values will produce various output resistances at each fault stage, and the related coordinated protection and control strategy needs to be adjusted accordingly. Therefore, in the first part of this paper, we analysed the DC side short circuit current mechanism and the fault current restraint characteristics of R-SFCLs. Subsequently, to verify the above analysis, the R-SFCL-based four-terminal MMC-MTDC with DC bipolar short fault modelling and simulation are presented in the next section. Finally, based on the above analysis and research, the advanced DC bipolar fault control and protection strategies of the R-SFCL-based MMC-MTDC system are discussed to promote further study of coordinated and protection control and the application of R-SFCLs in subsequent engineering applications. © 2021 IET Conference Proceedings. All rights reserved.

关键词： Timing circuits

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Applications and Prospects of Online Insulation Monitoring Technique Based on Broadband Frequency Response for Transformers in Voltage Source Converter System 2nd

Applications and Prospects of Online Insulation Monitoring T...

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Conference Proceedings of 2022 2nd International Joint Conference on Energy, Electrical and power Engineering

作者： Lu, Geye Zheng, Dayong Zhang, Pinjia State Key Lab of Security Control and Simulation of Power Systems and Large Scale Generation Equipment Tsinghua University Beijing100084 China

ISBN: (纸本)9789819943333

power electronic converters are widely applied in new power system. Converter transformers have a critical risk in safe and reliable operation due to the insulation ageing. At present, conventional transformer insulation monitoring methods are limited to low sensitivity, invasive sensors and sophisticated evaluation. The goal of this paper is to improve the performance of online insulation monitoring for converter transformers based on broadband frequency response. The significance of application promotion, the disadvantages of existing methods and the challenges from offline to online implementation are clarified. A novel technique based on inherent harmonics in voltage source converter system is investigated, which provides the prospect in improving the online monitoring performance with high reliability and non-invasiveness nature. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Insulation

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Degradation state assessment of rolling bearing based on variational mode decomposition and energy distribution 16th

Degradation state assessment of rolling bearing based on var...

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16th International Conference on Fracture and Damage Mechanics, 2017

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

ISBN: (纸本)9783035711684

Degradation state assessment of bearing is an important part of prognostic and health management (PHM) in rotating machinery. Generally, the energy distribution of frequency band is sensitive to degradation state for rolling bearing. Hence, a novel assessment method based on variational mode decomposition (VMD) and energy distribution is proposed in this work. Firstly, the VMD is used to decompose raw vibration signal into several components with different scales and frequency bands. These components is capable of reflecting the local characteristic of vibration signal. Then, the energy distribution of these components is utilized as feature vector. Finally, the different bearing states can be classified by the scatter plots of the first several principal components after principal component analysis (PCA). The analysis of an experimental dataset demonstrates the effectiveness of this methods. The comparative analysis shows the VMD is superior to traditional empirical mode decomposition (EMD) methods. © 2017 Trans Tech Publications, Switzerland.

关键词： Variational mode decomposition

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