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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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Design and experiments of two glued axially-laminated synchronous reluctance permanent magnetic motors

Design and experiments of two glued axially-laminated synchr...

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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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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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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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Condition Evaluation of power Cables Based on BiLSTM with Siamese Attention

Condition Evaluation of Power Cables Based on BiLSTM with Si...

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2023 Panda Forum on power and Energy, PandaFPE 2023

作者： Lin, Menglong Chen, Jianning Zhou, Yuanxiang Pan, Zehua Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China Beijing Electric Power Research Institute State Grid Beijing China

ISBN: (纸本)9798350321173

The fast and accurate state evaluation of cable plays an important role in the safe and reliable operation of power system. Thus a high-voltage cables condition evaluation model based on siamese-attention bidirectional long short-term memory (SA-BiLSTM) is proposed in this paper. First, the attention mechanism was used to optimize the BiLSTM network, which can complete parallel training while obtaining global information. then the optimized network was adopted to build a siamese neural network framework, realizing data classification by calculating the Euclidean distance between feature vectors. Finally, the model was trained and tested through the online monitoring data of high-voltage cables from engineering. The results showed that the accuracy rate, precision, recall rate, F1 score and Matthews correlation coefficient of the SA-BiLSTM model was increased at least by 7.92%, 11.79%, 11.41%, 12.04%, and 20.90%, respectively, compared with other models. © 2023 IEEE.

关键词： Long short-term memory

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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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Research and simulation on voltage stability control strategy for AC port of power electronic transformer 16

Research and simulation on voltage stability control strateg...

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16th IET International Conference on AC and DC power Transmission, ACDC 2020

作者： Shen, Yu Nie, Haozhe Cai, Weiqian Yuan, Liqiang Zhang, Chunpeng Zhao, Zhengming State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781839533914

With wide application of power electronic equipment in power system, voltage stability and power supply reliability need to be improved. In this paper, voltage sag caused by AC port load increase and the influencing factors are studies with a typical power electronic transformer topology as example. A calculation method which can estimate the port voltage sag performance according to the load impedance is proposed. In order to maintain the port voltage stability in the process of load increase, a voltage stability control strategy is proposed based on the double-loop control by increasing the voltage feedforward, which can improve the power supply quality and stability of power electronic transformer. Finally, the MATLAB/Simulink simulation results show that the proposed scheme is accurate and effective. © 2020 Institution of Engineering and Technology. All rights reserved.

关键词： MATLAB

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Rolling bearing fault feature extraction of casing vibration signal

Rolling bearing fault feature extraction of casing vibration...

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Society for Machinery Failure Prevention Technology Annual Conference 2017: 50 Years of Failure Prevention Technology Innovation, MFPT 2017

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

The health of rolling bearing plays an important part in the operation of rotating machinery like gas turbine engine. Health monitoring and fault diagnosis of rolling bearings based on vibration signals have been through great development these years. But when sensors are set on the casing instead of the bearing pedestal, and the surrounding structure is very complex, the diagnosis problem becomes much more complicated, which brings more challenges to the signal processing. In this paper, a set of signal processing methods are used to enhance and extract the impact features from casing vibration signals, and to realize the detection of rolling bearing faults. Aself-adaptive decomposition method called intrinsic time-scale decomposition (ITD) is applied to decompose the vibration signal into a series of proper rotation components and a monotonic trend, helping to extract dynamic features of the signal. Teager-Kaiser energy operator is a simple algorithm calculating the energy of a signal and is very sensitive to transient impact faults. As the fault feature transmitted to the casing is relatively week, autoregressive model (AR) and minimum entropy deconvolution (MED) are to enhance the non-stationary impact components. Experiments are taken on the rotor-bearing-casing test rig with minor defects in themain shaft bearing. Testing on the casing vibration signal, this fault feature enhancing and extracting method shows its remarkable ability in rolling bearing fault diagnosis.

关键词： Feature extraction

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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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Achieving Nearly 100% Targeted Conversion of NO to NO₂ through Cooperative Activation of Lattice Oxygen and Molecular Oxygen on Dual-Defect LaMnO₃

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Environmental Science and Technology 2025年 2025 May 20页

作者： Qian, Zhen Yuan, Bo Sheng, Shiwei Lai, Fei Chen, Jianjun Mi, Jinxing Ma, Zhao Hao, Runlong Li, Junhua Wang, Lidong Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control Department of Environmental Science and Engineering North China Electric Power University Baoding 071003 China State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China MOE Key Laboratory of Resources and Environmental Systems Optimization College of Environmental Science and Engineering North China Electric Power University Beijing 102206 China

Inhibiting the deposition of N species on the catalyst surface for the targeted oxidation of NO to NO2 is still a great challenge. Herein, a La and O dual-defective LaMnO3 (2U-L0.8MO) perovskite was fabricated using a... 详细信息

Inhibiting the deposition of N species on the catalyst surface for the targeted oxidation of NO to NO₂ is still a great challenge. Herein, a La and O dual-defective LaMnO₃ (2U-L_0.8MO) perovskite was fabricated using a urea-nonstoichiometric comodulation strategy, which achieved 97.6% NO oxidation efficiency at 210 °C and 300,000 h^-1, and was also capable of nearly 100% targeted oxidation of NO to NO₂, as well as exhibited excellent stability and recyclability. Characterizations and theoretical calculations unveiled that the urea-nonstoichiometric modulation method optimized the specific surface area and geometrical structure of perovskite, promoted the formation of La defects and oxygen vacancies (OVs), enhanced lattice oxygen activation and migration, and also facilitated the coadsorption of NO and O₂ and increased the d-band center of the perovskite. The synergistic activation of lattice oxygen and molecular oxygen along with the low-temperature oxidation mechanisms of NO was finally revealed: the comodulation strategy caused stretching and distortion of the 2U-L_0.8MO lattice, making its lattice oxygen susceptible to activation, thereby oxidizing adsorbed NO to NO₂ and simultaneously generating OVs. Afterward, O₂ would be captured by the abundant OVs on the 2U-L_0.8MO surface and converted to superoxide O₂^-, which could not only directly oxidize NO but also transform into single ¹O₂ on the adjacent Mn⁴⁺ site for the targeted oxidation of NO. This work realizes the coactivation of O₂ and lattice oxygen and also extends the understanding of the low-temperature-targeted oxidation of NO. © 2025 American Chemical Society.

关键词： cooperative activation LaMnO3 perovskite lattice oxygen activation low-temperature oxidation molecular oxygen activation targeted conversion of NO to NO2

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