检索结果-内蒙古大学图书馆

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

来源：评论

学校读者我要写书评

暂无评论

Travelling wave differential protection based on equivalent travelling wave 13

Travelling wave differential protection based on equivalent ...

引用

13th International Conference on Development in power system Protection 2016, DPSP 2016

作者： Tang, Lanxi Dong, Xinzhou Shi, Shenxing Wang, Bin State Key Laboratory of Control and Simulation of Power System and Generation Equipments Dept of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781785618260

Travelling wave (TW) differential protection fully utilizes the fault information contained in TW at both terminals of a transmission line, so it's a protection with high reliability and high selectivity. However, because TW differential protection needs a large amount of communication, it cannot be put into practical use. This paper proposes a TW differential protection which is based on equivalent travelling wave (ETW). Fault information is not lost during the process of getting ETW, so the proposed protection has the same reliability and selectivity with traditional TW differential protection. Because only several modulus maxima are needed to be sent to the opposite terminal, the traffic is largely reduced and the protection can operate much more rapidly. Extensive simulations validate the proposed protection.

关键词： Wavelet transforms

来源：评论

学校读者我要写书评

暂无评论

Performance evolution of NI-YSZ anode-supported Sofcs during initial-stage operation 17

Performance evolution of NI-YSZ anode-supported Sofcs during...

引用

17th International Symposium on Solid Oxide Fuel Cells, SOFC 2021

作者： Lyu, Zewei Han, Minfang Department of Energy and Power Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China

ISBN: (纸本)9781607685395

Performance evolution of typical Ni-YSZ anode-supported SOFCs during the initial-stage operation ( 20 h), regardless of the operating current. In the activation stage, the cell performance maintains stable or slightly increases due to the enhanced anode gas-phase diffusion. While in the subsequent aging stage, the cell performance decreases significantly and gradually approaches a plateau in about 100 hours, mainly due to the weakened anode charge transfer reaction and ionic transport processes. Therefore, it is suggested that more efforts should be focused on improving the stability of anode microstructure, especially the stability of anode functional layer. © 2021 Electrochemical Society Inc.. All rights reserved.

关键词： Chemical activation

来源：评论

学校读者我要写书评

暂无评论

Optimization of methane reforming for high efficiency and stable operation of SOFC stacks 17

Optimization of methane reforming for high efficiency and st...

引用

17th International Symposium on Solid Oxide Fuel Cells, SOFC 2021

作者： Liu, Yaodong Lyu, Zewei Han, Minfang Department of Energy and Power Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China

ISBN: (纸本)9781607685395

Solid Oxide Fuel Cells (SOFCs) provides an efficient and clean pathway to generate electricity. In addition to hydrogen, SOFCs also hold the possibility for the utilization of a variety of carbon containing fuels. A practical kilowatt-class SOFC system fueled by methane has been preliminarily integrated previously. This study intended to obtain the optimized working conditions for the prereformer, with which the SOFC module can exhibit higher electrical performance. Detailed thermodynamic analysis and experimental measurements of steam methane reforming (SMR) were carried out under different steam to carbon ratios (S/C) and temperatures, where the experimental results matched well with the thermodynamic calculation. Based on the optimized working condition of SMR, the electrical performance and stability of a planar single-layer stack (10×10 cm2) fueled by the reformate syngas was evaluated. The maximum electrical efficiency reached 65.39% (LHV) at 750 C, and 50-hour stable operation under 50% (LHV) electrical efficiency was achieved. © 2021 Electrochemical Society Inc.. All rights reserved.

关键词： Electrical efficiency

来源：评论

学校读者我要写书评

暂无评论

Lightning overvoltage suppression to UHV power transformer by ferromagnetic ring

Lightning overvoltage suppression to UHV power transformer b...

引用

作者： Zhang, Xiao He, Jinliang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

Lightning overvoltage protection is of great importance to the safety of devices in UHV GIS. In practice, insulation failure of UHV transformer due to lightning strike is often reported. The widely used UHV metal-oxide arresters can suppress the magnitude of lightning overvoltage but lack effectiveness on alleviating the steepness. A new protection method is proposed in this paper using ferromagnetic ring as supplement to the arresters in suppressing lightning overvoltage within UHV GIS. Moreover, equivalent model based on the characteristic of ferromagnetic material and factual dimensions of the ring is established. simulation of an actual 1000 kV GIS is carried out to thoroughly evaluate the lightning overvoltage suppressing effect of ferromagnetic rings with different materials and structure parameters. © 2012 Elsevier B.V. All rights reserved.

关键词： power transformers

来源：评论

学校读者我要写书评

暂无评论

Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

引用

Plasma Science and Technology 2017年第6期19卷 74-81页

作者： Yuanji CAI Yonggang GUAN Weidong LIU State Key Lab of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 People＇s Republic of China

Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary *** is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）*** this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike *** TEV waveforms during disconnector operations are recorded by a self-developed measurement system ***,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are *** transmission line theory is introduced to analyze the TEV and is validated by the experimental ***,the relationship between the TEV and the repeated strike process is *** proves that the pulse voltage of the TEV is proportional to the corresponding breakdown *** results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

关键词： transient enclosure voltage (TEV) gas-insulated switchgear (GIS) ultra-high-voltage (UHV) repeated strike process disconnector

来源：评论

学校读者我要写书评

暂无评论

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

引用

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

来源：评论

学校读者我要写书评

暂无评论

Experimental investigation and analysis of some common faults for wind turbine 68

Experimental investigation and analysis of some common fault...

引用

68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

作者： Yang, Wenguang Li, Shaohua Jiang, Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

This paper focus on the fault characteristic by experimental research. A test rig is built for the direct driving stall fix-pitch horizontal axis wind turbine. 8 signals are collected by the experiment system, including wind speed, rotor rotational speed, shaft torque, the output electric power, vertical and horizontal vibration displacement of main shaft, vibration acceleration of the front bearing pedestal and the back bearing pedestal. 11 common wind turbine faults are researched by experiment. These faults are rotor mass imbalance, pneumatic asymmetry, airfoil changed, yaw fault, shaft horizontal misalignment, shaft vertical misalignment, front bearing pedestal looseness, rear bearing pedestal looseness, front bearing outer ring fault, front bearing inner ring fault, and front bearing roller fault. Several signal analysis methods, which are waveform analysis, orbit analysis, amplitude domain analysis, frequency domain analysis and envelope spectrum analysis, are adopted to extract characteristics from vibration signals. The influence on output power and vibration characteristics of these faults is presented by comparing with normal operation. The findings can be used to guide wind turbine fault diagnosis in engineering applications.

关键词： Wind

来源：评论

学校读者我要写书评

暂无评论

Finite element analysis on damping characteristics for vibro-impact of integral shroud blade

Finite element analysis on damping characteristics for vibro...

引用

Joint Conference on Society for Machinery Failure Prevention Technology Conference, MFPT 2015 and ISA's 61st International Instrumentation Symposium, IIS 2015 - Technology Evolution: Sensors to systems for Failure Prevention

作者： Wang, Nan-Fei Jiang, Dong-Xiang Chen, Jing-Ming State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

By using theoretical and experimental methods, dynamic characteristics of turbine blades with integral shrouds are studied, and the mechanism of vibro-impact and the effective factors of integrally shrouded blades are mainly presented. By means of finite element calculation, the dynamic frequencies and vibration mode shapes of single shrouded blade are explored under different rotating speeds. The three-dimensional entity unit integral dynamics equation of blades with vibro-impact are established by using nonlinear damping model in this paper. With the help of 3D software Solidworks, the solid model of blade is built. With the aid of FEA software ANSYS, the dynamics and static characteristics of single blade are obtained. Meanwhile, by building the model to set different shroud clearance and exciting force amplitude, the relationships between displacement of blade tip and influence of such as blade shroud clearance and exciting force amplitude are demonstrated. The results of the analysis indicate that the collision structural is an ideal damping structure. As the clearance between blade shrouds is smaller, the damping effect is better. Moreover, results show that blades adopting collision damping mechanism can achieve good damping effect when the blades are subjected to greater exciting force.

关键词： Finite element method

来源：评论

学校读者我要写书评

暂无评论

Modal analysis of wind turbine tower

Modal analysis of wind turbine tower

引用

2010 2nd World Non-Grid-Connected Wind power and Energy Conference, WNWEC 2010

作者： Chen, Jie Jiang, Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781424489213

As the support structure of wind turbine, the tower bears alternating loads of wind when the wind turbine runs. To ensure the reliability of the wind turbine, it's necessary to carry out modal analysis on the tower, and this would prevent the natural frequency of the tower close to the rated speed of wind turbine. In this paper, finite element analysis of the tower is solved using ANSYS, and the natural frequencies and modes of the tower are presented. After comparing the results of three models, a simple model for modal analysis, which can be calculated in short time, is finally determined. © 2010 IEEE.

关键词： Modal analysis

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：