检索结果-内蒙古大学图书馆

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

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

An unsupervised hourly weather status pattern recognition and blending fitting model for PV system fault detection

引用

Applied Energy 2022年 319卷

作者： Jiaqi Qu Zheng Qian Yan Pei Lu Wei Hamidreza Zareipour Qiang Sun School of Instrumentation and Optoelectronic Engineering Beihang University Beijing China School of Electronics and Information Engineering Beihang University Beijing China The Department of Electrical and Computer Engineering University of Calgary Calgary Canada State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

Detecting PV system faults in a timely fashion is important to ensure the safe operation of equipment and reduce their impact on the economy of the PV systems. It is necessary to further improve the time-sensitive performance evaluation of the system. However, the hourly weather scenario segmentations are seldom considered during the hour-level online monitoring process. Therefore, a hybrid method based on unsupervised hourly weather status pattern recognition and blending fitting model is proposed for hourly fault detection to improve the performance evaluation of PV systems. The proposed solution includes three parts, firstly, in the data preprocessing stage, the measured power with the errors and noise under normal operation situation caused by the environment changes is corrected by monthly linear fitting. Secondly, an unsupervised hourly weather status pattern recognition method is constructed using the measured radiation data, including unsupervised clustering and the Multiclass-GBDT-LR classification process. Finally, after eliminating the anomalies and errors, the blending fitting model of the hourly sub-weather status is established. Through the analysis of power plants in Australia and China, the proposed solutions are validated and evaluated to be superior to existing data-driven solutions in terms of fitting accuracy, detection validity, and response time. Numerical results of case studies indicate that the developed methodology under sub-weather has improved the detection accuracy up to 97.71% and 99.29% compared to benchmark models.

关键词： Photovoltaic systems performance Hourly fault detection Unsupervised hourly weather status pattern recognition Blending fitting model

来源：评论

学校读者我要写书评

暂无评论

Modeling and simulation analysis of dual-rotor vibration system with multiple faults

Modeling and simulation analysis of dual-rotor vibration sys...

引用

Society for Machinery Failure Prevention Technology Conference 2018: Intelligent Technologies for equipment and Human Performance Monitoring, MFPT 2018

作者： Yang, Yizhou Liu, Chao 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

Dual-rotor system is an important rotor form in rotating machinery like gas turbine engine. Its complex structure results in rich dynamical behaviors and more probability to failure. The modeling and simulation of the dual-rotor system can help to understand its dynamic characteristics and provide theoretical support for the design, operation and maintenance. In this paper, a dynamic model of a dual-rotor system with multiple rotor faults is established. The dual-rotor vibration model without any fault is built by finite element method, where the two shafts are connected by an inter-shaft bearing and nonlinear models of rolling element bearing and squeeze film damper are considered. The numerical integration method of Newmark-β is used to obtain the steady-state vibration response of the system. Then rotor faults are introduced to the system model, including unbalance, misalignment, looseness and rub-impact. The steady-state responses of single faults in the dual-rotor system are analyzed and typical fault features are obtained. Then coupling characteristics between different rotor faults, and the influences of the squeeze film dampers on the dynamic characteristics and fault features of the system are studied. © 2018 Proceedings of the 9th International Symposium on Imprecise Probability.

关键词： Rotating machinery

来源：评论

学校读者我要写书评

暂无评论

CCF early warning method of LCC-HVDC based on XGBoost algorithm

CCF early warning method of LCC-HVDC based on XGBoost algori...

引用

8th Renewable power Generation Conference (RPG 2019)

作者： Zhizhong Li Bin Wang Haigang Wang Bin Yu Min Xie Shi Chen Xinzhou Dong Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China State Grid Anhui electric power company Hefei 230061 China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

The lack of analytical mechanism of continuous commutation failure (CCF) process hinders the development of CCF early warning algorithm and further obstructs the coordination strategy of relay protection between AC and DC size in hybrid grid. However, summarizing the protection threshold of CCF in the form of electrical quantity analytically under different fault types is a nontrivial pattern recognition problem. To overcome the difficulty of directly analysing the electromagnetic process of CCF, a statistical learning modelling approach is adapted to propose a CCF warning system, in which XGBoost algorithm was used as the backbone to regress on the relationship between AC/DC electrical quantities and the possibility of the occurrence of CCF. The design of the feature vector in XGBoost-based classifier considers not only the analytical expression of key electrical quantity during single commutation failure but also the important state variable of control system. Additionally, a special data windowing method was proposed to enrich of information encoded by the feature vector while ensuring the speed requirement posed by the protection system. Validation on multi-fault scenes simulation shows that the proposed early warning system can trigger warning signal correctly with sufficiently small measured data required, proving the practicability in engineering practice.

关键词：

来源：评论

学校读者我要写书评

暂无评论

ANALYSIS OF FATIGUE LIFE LOSS OF DRIVETRAIN OF DOUBLY-FED WIND TURBINES UNDER SHORT-CIRCUIT FAULT OF power GRID

ANALYSIS OF FATIGUE LIFE LOSS OF DRIVETRAIN OF DOUBLY-FED WI...

引用

International Conference on Renewable power Generation

作者： Qiu Shilong Li Hui Gong Lijiao Wang Bin Chai Zhaoseng Wu You Department of Mechanical and Electrical Engineering Shihezi University Shihezi China State Key Laboratory of Power Drivetrain Equipment and System Security Chongqing University Chongqing China State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Department of Electrical Engineering) Tsinghua University Haidian District Beijing China State Key Laboratory of Power Drivetrain Equipment and System Security Chongqing University Chongqing China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

The shafting drivetrain of the doubly fed wind turbine is the part with the highest failure rate. The electromagnetic torque fluctuation caused by the grid fault easily results in the torsional vibration fatigue loss of the shaft. Accordingly, the influences of drivetrain fatigue life loss under different grid faults require investigation. Firstly, the four-mass model of the drivetrain is constructed on the basis of MATLAB/Simulink. Secondly, the electromagnetic torque response under short-circuit fault of the grid is obtained via model simulation. Finally, the effects of different types of grid faults on the fatigue life of the drivetrain are analysed through Mlife. Results show that the electromagnetic torque fluctuation load generated by grid fault has no apparent influence on the fatigue life of the drivetrain in the short term, but the cumulative effect of short-term damage will aggravate the fatigue life loss of the drivetrain and increase the failure risk of the component. The electromagnetic torque generated by the three-phase symmetrical short-circuit is the most violent and has the maximum effect on the fatigue life of the drivetrain.

关键词： WIND TURBINE SHORT-CIRCUIT FAULT TORSIONAL VIBRATION FATIGUE LIFE DRIVETRAIN

来源：评论

学校读者我要写书评

暂无评论

Transient Behaviors of Space Charge in Low-density Polyethylene Films at Prebreakdown Under Temperature Fields

Transient Behaviors of Space Charge in Low-density Polyethyl...

引用

中国物理学会第二十二届全国静电学术年会

作者： Ling Zhang Zekai Lu Yuanxiang Zhou Zhaowei Peng Zixia Cheng Yonggang Guan State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department School of Electrical Engineering Zhengzhou UniversityZhengzhou 450001China

Currently,insulation performance of high voltage DC(HVDC)power cables is still of critical significance challenge in both engineering application and fundamental *** example,HVDC cable insulation suffers breakdown under the conditions of cold start and load cycling tests,and the presence of space charge at high temperatures causes electric field distortion within the ***,the operating temperature of HVDC cables could only reach 70℃at *** work intends to carry out research on the effect of temperature on space charge characteristics of low-density polyethylene(LDPE)films at prebreakdown under a linearly ramping voltage,which is of great significance for further understanding and improving the operating temperature and breakdown strength of HVDC ***-free LDPE film with a thickness of 100 μm was purchased from GoodFellow *** improved space charge measurement system was developed with a high-speed measurement interval of 1 ms,a high voltage pulse of 120 V,and a pulse width of 5 ns.A linearly ramping voltage of 0.5 kV/s was selected and cut off after breakdown *** and steady behaviors of space charge was comprehensively sudied under a linearly ramping voltage of 500 V/s at 30℃and 70℃,*** results show that negative charge was rapidly injected and accumulated near the anode at a relatively low electric field at 70℃.As the applied electric field gradually increased,the anode appeared a significant positive charge *** phenomenon occurred when charge packets were injected to a certain distance of~30 μ*** the contrast,there was only negative charge injection and accumulation in the bulk of LDPE films at 30℃,and breakdown was not observed even when the voltage rose to-30 *** was found that the anode had a positive space charge packet injection at 30℃and slowly migrated to the cathode,and the entire transit process took tens of *** the internal electric field distribution,the ma

关键词： LDPE prebreakdown transient space charge internal field distortion carrier mobility

来源：评论

学校读者我要写书评

暂无评论

Charge Evolution and Dielectric Property of Three-phase Polypropylene Composites With Enhanced Mechanical Performance

Charge Evolution and Dielectric Property of Three-phase Poly...

引用

中国物理学会第二十二届全国静电学术年会

作者： Ling Zhang Zhaowei Peng Yuanxiang Zhou Zekai Lu Yonggang Guan Zixia Cheng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department School of Electrical Engineering Zhengzhou UniversityZhengzhou 450001China

High voltage DC(HVDC)power cable technology has the advantages of large transmission capacity,low loss,negligible electromagnetic environmental effect,and trackless corridor,etc.,which make it capable to solve the significant problem of power transmission channels during the fast development of electric ***,it also contributes to eco-friendly,resource-saving,safe,and reliable goal of power transmission *** to common crosslinked polyethylene materials,isotactic polypropylene(iPP)has the advantages of non-crosslinking,high-temperature-resistant,recyclable,low production cost,and free maintenance work,and has been a hot spot in the research field of high performance HVDC cable insulating ***,iPP is a thermoplastic limited by its impact strength,especially at low temperatures,because of its high degree of crystallinity and high glass transition *** of the common methods used to increase the impact strength is the addition of low-molecular elastomer materials or nucleating agents(NAs)into the iPP matrix,which is blended with the polymer in the molten *** previous investigations with the binary blending system have demonstrated that improved impact resistance usually was accompanied by decreasing the stiffness or deteriorating its original electrical properties in some *** order to achieve an optimum balance of macroscopic properties,adding several components is often necessary in polymer *** aim of this work is to investigate the synergistic effects on mechanical and electrical properties between NAs and different elastomers in iPP *** have shown that increasing the β-crystal content can improve its electrical property and elastomer can strengthen its mechanical performance.,Thus,three-phase iPP blends(iPP-β-x,x refers to the elastomer)were prepared with the incorporation of arylamide derivative β-NAs(TMB-5,0.2 wt%)and different elastomers(15 wt%)including styrene-bethylene butylene-b-styr

关键词： isotactic polypropylene β nucleating agent elastomer impact strength space charge

来源：评论

学校读者我要写书评

暂无评论

Optimization of Operation Strategy of Virtual power Plants Involved in Peak Shaving

Optimization of Operation Strategy of Virtual Power Plants I...

引用

China International Electrical and Energy Conference (CIEEC)

作者： Qiuchen Yun Wenzhong Gao Fang Zhang Lin Cheng Liting Tian School of Electrical Engineering Beijing Jiaotong University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9781728116754

ISBN: (纸本)9781728116761

In recent years, as the consumption rate of renewable energy has increased, the impact of renewable energy on the power grid has also increased. Currently, distribution network system operators and transmission line system operators are unable to acquire and control the operational status of renewable energy sources such as wind power photovoltaics. These phenomena pose a significant challenge to the safety and stability of the operation of the power system. The virtual power plant is a feasible solution, based on the data acquisition terminal of advanced communication technology, decentralized control or centralized control of DER. Based on the virtual power plant, this paper aggregates three types of resources, wind power, photovoltaic, and electric vehicles, which are typical on the supply side and the demand side. Then, the virtual power plant is regarded as a whole to accept the dispatching instructions of the power grid, formulate the operational strategy of the internal resources of the virtual power plant, and participate in the peaking service.

关键词：

来源：评论

学校读者我要写书评

暂无评论

A control Strategy of the Grid Support for Photovoltaic Inverter Based on control-hardware-in-the-loop simulation

A Control Strategy of the Grid Support for Photovoltaic Inve...

引用

International Conference on Advanced power System Automation and Protection (APAP)

作者： Shuang LI Gangquan SI Kai QU Zeyu YANG Guoqing HE School of Electrical Engineering Xi'an Jiaotong University State Key Laboratory of Electrical Insulation and Power Equipment Xi’an China China Electric Power Research Institute State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems Beijing China

ISBN: (数字)9781728117225

ISBN: (纸本)9781728117232

With the increasing proportion of renewable energy generation, the grid lost strong electrical support for renewable energy generating units, which leads to a series of new grid- connected stability problems. Therefore, it is of great significance to enhance the acceptance of PV power generation by improving the grid-connected voltage quality of PV inverters. A coordinated control strategy for PV inverters with the grid support capability was proposed in this paper, which fully utilized the voltage and frequency regulation capability of grid- connected inverters. At the same time, a real-time simulation system of PV grid-connected inverter based on FPGA simulator and eHS modeling technology was built by RT-LAB simulation platform. Finally, some relevant experiments are carried out on the simulation platform when the grid-connected voltage is disturbed. And the simulation results verified the validity of the proposed control strategy.

关键词： Inverters Voltage control Reactive power power generation Frequency control power system stability Threshold voltage

来源：评论

学校读者我要写书评

暂无评论

Carbon Wrapped Rutile TiO2 Nanoparticles for Dinitrogen Electroreduction to Ammonia at Ambient Conditions

Carbon Wrapped Rutile TiO2 Nanoparticles for Dinitrogen Elec...

引用

中国化学会2019能源材料和缺陷化学研讨会

作者： Xiaoyang Cui Xiao-meng Liu Shao-xin Wei Yi-ming Cui Ling Zhang Qiang Zhang Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology Department of Chemical Engineering Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University

Catalytic conversion of dinitrogen（N） into ammonia under ambient conditions represents one of the Holy Grails in sustainable chemistry. As a potential alternative to the Haber-Bosch process, electroreduction of N to NH is attractive owing to its renewability, sustainability and flexibility. However, electrocatalysts with high catalytic activity and high selectivity are rare because of the kinetically complex and energetically challenging N reduction reaction（NRR） process. In particular, the competing hydrogen evolution reaction（HER） is crucial for the low selectivity.

关键词： TiO Carbon Wrapped Rutile TiO2 Nanoparticles for Dinitrogen Electroreduction to Ammonia at Ambient Conditions

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：