期刊文献+
共找到1,182篇文章
< 1 2 60 >
每页显示 20 50 100
Suppression of low-frequency ultrasound broadband vibration using star-shaped single-phase metamaterials
1
作者 Rui Zhao Jian Zheng +4 位作者 Jin Guo Yunbo Shi Hengzhen Feng Jun Tang Jun Liu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第4期217-224,共8页
In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation pr... In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment. 展开更多
关键词 Star-shaped metamaterials BROADBAND Vibration attenuation low-frequency ultrasound vibration transmission loss
下载PDF
Analysis of vibration and frequency transmission of high speed EMU with flexible model 被引量:4
2
作者 Zun-Song Ren Guang Yang +1 位作者 Shan-Shan Wang Shou-Guang Sun 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第6期876-883,共8页
When the operation speed of the high-speed train increases and the weight of the carbody becomes lighter,not only does the sensitivity of the wheel/rail contact get higher,but also the vibration frequency range of the... When the operation speed of the high-speed train increases and the weight of the carbody becomes lighter,not only does the sensitivity of the wheel/rail contact get higher,but also the vibration frequency range of the vehicle system gets enlarged and more frequencies are transmitted from the wheelset to the carbody.It is important to investigate the vibration characteristics and the dynamic frequency transmission from the wheel/rail interface to the carbody of the high-speed electric multi-uint(EMU).An elastic highspeed vehicle dynamics model is established in which the carbody,bogieframes,and wheelsets are all dealt with as flexible body.A rigid high-speed vehicle dynamics model is set up to compare with the simulation results of the elastic model.In the rigid vehicle model,the carbody,bogieframes and wheelsets are treated as rigid component while the suspension and structure parameters are the same as used in the elastic model.The dynamic characteristic of the elastic high speed vehicle is investigated in time and frequency domains and the di ff erence of the acceleration,frequency distribution and transmission of the two types of models are presented.The results show that the spectrum power density of the vehicle decreases from the wheelset to the carbody and the acceleration transmission ratio is approximately from 1%to 10%for each suspension system.The frequency of the wheelset rotation is evident in the vibration of the flexible model and is transmitted from the wheelset to the bogieframe and to thecarbody.The results of the flexible model are more reasonable than that of the rigid model.A field test data of the high speed train are presented to verify the simulation results.It shows that the simulation results are coincident with the field test data. 展开更多
关键词 High-speed EMU Vibration transmission flexible model ACCELERATION Power spectrum density
下载PDF
Dynamic Simulation for Rigid-Flexible Coupling Model of Gear Transmission System Based on ADAMS 被引量:1
3
作者 陈材 石全 +1 位作者 王广彦 戈洪宇 《Journal of Donghua University(English Edition)》 EI CAS 2016年第2期192-195,共4页
The influence of the flexible body for the motion of gear transmission system is analyzed and the foundation for a more accurate assessment of gear transmission system is established when it has battle damage faults. ... The influence of the flexible body for the motion of gear transmission system is analyzed and the foundation for a more accurate assessment of gear transmission system is established when it has battle damage faults. By using Pro / E software,the virtual prototype model of gear transmission system in the speed reducer is established,and the rigid model and rigid-flexible coupling model are simulated respectively in ADAMS to obtain the data of gear meshing force. It can be concluded that rigid-flexible coupling model can reflect the real motion better than rigid model by comparing the simulation data of two models. 展开更多
关键词 ADAMS gear transmission rigid-flexible coupling SIMULATION
下载PDF
The Effective Enhancement of Power System Security by Flexible Transmission Line Impedance with Minimal Rescheduling of Generators
4
作者 Karuppasamy Muthulakshmi R.M. Sasiraja Selvarajan Mukesh Muthu 《Circuits and Systems》 2016年第4期381-389,共9页
After the digital revolution, the power system security becomes an important issue and it urges the power producers to maintain a well secured system in order to supply a quality power to the end users. This paper pre... After the digital revolution, the power system security becomes an important issue and it urges the power producers to maintain a well secured system in order to supply a quality power to the end users. This paper presents an integrated Corrective Security Constrained Optimal Power Flow (CSCOPF) with Flexible Transmission Line Impedance (FTLI) to enhance the power system security. The corrective approach of SCOPF is chosen, because it allows the corrective equipment to bring back the system to a stable operating point and hence, it offers high flexibility and better economics. The concept of FTLI arises from the ability of FACTS devices such as Thyristor Controlled Series Capacitor (TCSC), which can vary the line reactance to a certain extent. An enhanced security can be achieved by incorporating FTLI into the CSCOPF problem, since the power flow in a system is highly dependent on the line reactance. FTLI based CSCOPF can reduce the amount of rescheduling of generators, but it will result in an increased number of variables and thus, the complexity to the optimization process is increased. This highly complex problem is solved by using nonlinear programming. The AC based OPF model is preferred, since the corrective security actions require highly accurate solutions. IEEE 30 bus system is used to test the proposed scheme and the results are compared with the traditional CSCOPF. It can be seen that the proposed idea provides a notable improvement in the reduction of cost incurred for restoring the system security. 展开更多
关键词 flexible transmission Line Impedance Power System Security Security Constrained Optimal
下载PDF
基于Flexible YOLOv7的输电线路绝缘子缺陷检测和故障预警方法 被引量:9
5
作者 宋智伟 黄新波 +1 位作者 纪超 张烨 《高电压技术》 EI CAS CSCD 北大核心 2023年第12期5084-5094,共11页
电力设备的平稳运行是保障居民生产生活的重要前提。输电线路绝缘子缺陷尺寸较小,传统的目标检测算法通常难以识别到缺陷目标,误检、漏检率较高。针对不同材质绝缘子缺陷检测存在目标过小、遮挡、背景复杂等难题,提出了一种基于Flexible... 电力设备的平稳运行是保障居民生产生活的重要前提。输电线路绝缘子缺陷尺寸较小,传统的目标检测算法通常难以识别到缺陷目标,误检、漏检率较高。针对不同材质绝缘子缺陷检测存在目标过小、遮挡、背景复杂等难题,提出了一种基于Flexible YOLOv7的绝缘子缺陷检测算法。该算法继承了YOLOv7网络的E-ELAN结构、Rep重参数化和辅助训练策略,并且在特征提取的过程中集成GAM注意力机制以放大显著的跨维度接受区域,通过高效的Ghost SPPCSPC结构减少模型训练过程中的参数冗余,引入Efficient IOU Loss重点关注高质量的anchors提升原始模型的检测精度。最后通过图像后处理技术对绝缘子缺陷进行等级划分与精细计算,并结合算法部署开发了绝缘子缺陷故障检测系统用于故障的提前预警。实验结果表明,该算法在密集目标、遮挡、小目标缺陷检测中的平均准确率AP、召回率Recall、相关指标F1指标均领先于当前先进的几类目标检测算法,在复杂环境下的绝缘子缺陷检测和故障预警方面具有一定的现实意义。 展开更多
关键词 绝缘子缺陷检测 flexible YOLOv7 GAM注意力机制 Efficient IOU Loss 图像后处理技术 输电线路故障预警
下载PDF
Dynamic Characteristics of Transmission System for the Internal Grinder 被引量:2
6
作者 伍建国 孙庆鸿 +2 位作者 毛海军 郁文凯 蔡英 《Journal of Southeast University(English Edition)》 EI CAS 2002年第4期302-305,共4页
The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relations... The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new ... 展开更多
关键词 transmission system dynamic characteristic modal flexibility elasticity distribution rate
下载PDF
Influence of equipment excitation on flexible carbody vibration of EMU 被引量:8
7
作者 Huailong Shi Ren Luo +2 位作者 Pingbo Wu Jing Zeng Jinying Guo 《Journal of Modern Transportation》 2014年第4期195-205,共11页
To study the vibration transmission character istics of a flexible carbody and its suspended equipment, a vertical mathematical model of highspeed electric multiple unit was established with equipment excitation consi... To study the vibration transmission character istics of a flexible carbody and its suspended equipment, a vertical mathematical model of highspeed electric multiple unit was established with equipment excitation considered. And the dynamic unbalance and impact turbulence excita tion from equipment were taken into account in a single stage and twostage vibration isolation system, respectively. Results show that the excitation transferred to carbody increases with suspension stiffness but decreases with the equipment mass increasing; the vibration transmission can be reduced by increasing the equipment mass or reduce the suspension stiffness. To avoid vibration resonance, the dynamic unbalance frequency of equipment should be out of the possible range of the carbody flexible modes, and a small stiffness should be applied to reduce the impact tur bulence. A small stiffness, however, would result in a large movement of the equipment which is limited by the static deflection requirement, while a great stiffness will transfer high frequency vibration. Therefore, a preferred stiffness should make the suspension frequency of equipment a bit greater than the first bending mode of carbody. Additionally, a 3D rigidflexible coupled dynamics model was built to verify the mathematical analysis, and they show good agreements. Results show that a twostage isolation could reduce the excitation transmission and make the vibration of carbody and equipment acceptable. 展开更多
关键词 flexible carbody Suspended equipment Vibration transmission Dynamic unbalance IMPACT
下载PDF
Computer Simulation on Quasi-ellipsoidal Gear Transmission
8
作者 李瑰贤 刘俐平 +1 位作者 李华敏 毕诸明 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 1995年第4期42-45,共4页
Quasi-ellipsoidal gear transmission mechanism, which is the newest transmission mechanism used for robot flexible wrist at present, has simple structure, light weight,small dimension, high sensitivity and can accurate... Quasi-ellipsoidal gear transmission mechanism, which is the newest transmission mechanism used for robot flexible wrist at present, has simple structure, light weight,small dimension, high sensitivity and can accurately carry out the motion transmission in all-direction. It is a new type of transmission used for robot flexible wrist at present. Different from ordinary transmission mechanisms it is a spatial mesh with double DOF. Its design is complicated, and there are many approximate treatments in checking interference of flank and distribution of teeth. The purpose of this paper is to verify the reliability of the design by means of computer simulation. 展开更多
关键词 ss: flexible WRIST quasi-ellipsoidal GEAR transmission COMPUTER simulation
下载PDF
Research on Transmission Accuracy Characteristic Analysis of RV Reducer 被引量:7
9
作者 TAN Peng QI Houjun +2 位作者 HAN Lin FENG Juntao MA Dongsheng 《International Journal of Plant Engineering and Management》 2019年第3期157-168,共12页
The accuracy of RV reducer transmission is mainly affected by the transmission accuracy. Taking the high precision RV-80E reducer as the research object, aiming at its structural characteristics, the rigid-flexible co... The accuracy of RV reducer transmission is mainly affected by the transmission accuracy. Taking the high precision RV-80E reducer as the research object, aiming at its structural characteristics, the rigid-flexible coupling model of RV reducer is established by using ADAMS multi-body dynamics simulation software, and the correctness of the model is verified. At the same time, the rigid-flexible coupling model is used to design several groups of simulation prototypes with different errors, and the influence of different error factors on the transmission accuracy of the whole machine is analyzed by simulation. Finally, through different error factors, it is concluded that the error combination of positive equidistance+negative offset or negative equidistance+positive offset can effectively reduce the influence of transmission error on the transmission accuracy of the whole machine. 展开更多
关键词 RV REDUCER rigid-flexible coupling transmission ERROR transmission ACCURACY
下载PDF
Fault Location Method for STATCOM Connected Transmission Lines Using CCM 被引量:1
10
作者 R. Ilango T. Sree Renga Raja 《Circuits and Systems》 2016年第10期3131-3141,共12页
Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to loca... Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%. 展开更多
关键词 Distance Relay Fault Location flexible AC transmission Systems (FACTS) Power System Protection Static Synchronous Compensator (STATCOM)
下载PDF
Research on Intelligent Control and protection of flexible HVDC
11
作者 Runfeng Zhang 《International Journal of Technology Management》 2014年第2期29-31,共3页
This paper introduces the working principle of HVDC control and protection system. And the paper summarizes the flexible HVDC technology features and application fields and describes the composition and software intel... This paper introduces the working principle of HVDC control and protection system. And the paper summarizes the flexible HVDC technology features and application fields and describes the composition and software intelligent flexible HVDC control and protection system configuration. Finally, the simulation results are also given, experimental results show: HVDC flexible intelligent control and protection has a good control effect in the steady state and transient process, suitable for practical engineering application. 展开更多
关键词 flexible DC transmission Pulse Wide Module Intelligent control
下载PDF
Dynamic Analysis on the Main Transmission Device of Wooden Ice Cream Sticks Branding Machine
12
作者 LIU Wenzhi HUANG Mingjun +1 位作者 LI Weiguo MA Zhibin 《Journal of Donghua University(English Edition)》 EI CAS 2019年第3期234-238,共5页
In order to reduce the labor intensity,improve the production efficiency and enhance the equipment stability and the branding accuracy of the pattern,we have completed a double-row high-efficiency wooden ice cream sti... In order to reduce the labor intensity,improve the production efficiency and enhance the equipment stability and the branding accuracy of the pattern,we have completed a double-row high-efficiency wooden ice cream stick branding machine structural design.The rigid-flexible coupling dynamics model is established and the movement and stress of the first-stage chain drive are calculated and analyzed.The comparison of the theoretical calculation results shows that the dynamic modeling and the structural design of the equipment are reasonable and the result of dynamic calculation also provides the basis of load data for dynamic strength calculation of structural components. 展开更多
关键词 ice CREAM BRANDING MACHINE rigid-flexible coupling multi-body dynamics CHAIN drive transmission
下载PDF
Towards a (More) Electronic Transmission and Distribution (eT&D)
13
作者 Don Tan Damir Novosel 《CES Transactions on Electrical Machines and Systems》 2017年第1期15-25,共11页
The challenges and the path towards a(more)electronic transmission and distribution(eT&D)is presented in this paper.The challenges are first identified together with key stakeholders in the drive for grid moderniz... The challenges and the path towards a(more)electronic transmission and distribution(eT&D)is presented in this paper.The challenges are first identified together with key stakeholders in the drive for grid modernization.A fundamental question is then asked about the investment priority.Six basic characteristics are reviewed,leading to the composition of structured microgrids as the basic functional cell of a modern grid.One example of fractal radial structure and one fractal meshed structure are presented.The likely evolution path is then proposed together with basic technology sets.Specific foundation technologies are discussed in detail,including adiabatic power conversion,3MC technology,medium voltage conversion,distribution-level electronic power transformer and FACTs hardware integration,and back-to-back converters as a universal interconnect element.The rapidly emerging on-wire sensing technology is also discussed.It is pointed out that the distribution-level large electronic power transformer will provide a key component to enable hybrid ac/dc grid flow control and ancillary support for a flexible electronic transmission and distribution(eT&D)systems. 展开更多
关键词 All things grid connected electric power systems electronic transmission&distribution(eT&D) energy solutions flexible electronic transmission systems(FETS) grid modernization large electronic power transformers 3MC converters renewable energy.
下载PDF
基于新能源-负荷相似性的源荷储协调调峰优化调度 被引量:3
14
作者 王婷 李凤婷 +1 位作者 周远翔 崔巍 《电力自动化设备》 EI CSCD 北大核心 2024年第3期15-21,共7页
合理利用可调节负荷的响应特性来实现源荷储的协调调度,可有效缓解新能源、负荷的不确定性所带来的调峰压力。基于新能源-负荷(NER-L)相似性,建立可调节负荷响应目标。基于相关系数,建立能准确刻画负荷对新能源出力跟踪匹配程度的NER-L... 合理利用可调节负荷的响应特性来实现源荷储的协调调度,可有效缓解新能源、负荷的不确定性所带来的调峰压力。基于新能源-负荷(NER-L)相似性,建立可调节负荷响应目标。基于相关系数,建立能准确刻画负荷对新能源出力跟踪匹配程度的NER-L相似性指标,并将指标引入所建源荷储协调调峰的双阶段优化调度模型。第一阶段模型以NER-L相关系数最大为目标,确定可调节负荷在各时段的响应功率并获得最优电网负荷;第二阶段模型以弃风弃光量最小、调峰运行成本最低为目标,优化火电机组及储能出力。以IEEE 30节点系统为例,对NER-L相似性、净负荷峰谷差、系统调峰运行经济性及新能源弃电功率进行计算分析,结果验证了所提模型的有效性。 展开更多
关键词 新能源 可调节负荷 储能 相似性 调峰 协调调度
下载PDF
考虑电动汽车充放电的输配协同能量-灵活性市场出清机制 被引量:2
15
作者 姜涛 吴成昊 +2 位作者 李雪 张儒峰 付麟博 《电力系统自动化》 EI CSCD 北大核心 2024年第7期210-224,共15页
为应对输电网对灵活性资源的迫切需求,挖掘配电网分布式资源的灵活性支撑潜力,首先,构建市场环境下电动汽车的车-网互动响应模型,分析不同充放电方式下电动汽车的需求响应能力,为电动汽车参与市场环境下电网调度控制提供模型基础;然后,... 为应对输电网对灵活性资源的迫切需求,挖掘配电网分布式资源的灵活性支撑潜力,首先,构建市场环境下电动汽车的车-网互动响应模型,分析不同充放电方式下电动汽车的需求响应能力,为电动汽车参与市场环境下电网调度控制提供模型基础;然后,计及配电网运营商对需求侧灵活性资源的聚合作用,以购买电力和灵活性资源总成本最低为目标,构建考虑电动汽车充放电方式的输配协同能量-灵活性市场出清模型,通过协调控制输配电网中各类灵活性资源来满足输电网的灵活性需求;最后,通过修改的IEEE 33节点输电网与2个IEEE 33节点配电网耦合的测试系统对所提输配协同能量-灵活性市场出清方法的有效性进行分析与验证。结果表明,所提方法可提升电力系统的运行经济性和灵活性。 展开更多
关键词 能量市场 灵活性市场 输配协同 市场出清 分布式资源 电动汽车 充放电方式
下载PDF
一种具有重合闸功能的限流式直流断路器
16
作者 陶彩霞 王玥 +1 位作者 高锋阳 杨乔礼 《高压电器》 CAS CSCD 北大核心 2024年第8期43-52,共10页
为提高柔性直流输电系统发生短路故障后高压直流断路器的故障隔离、限流及重合闸恢复能力,在现有直流断路器结构基础上提出一种具有重合闸功能的限流式直流断路器(RCL-HDCB)。RCL-HDCB方案改进了断路器的限流支路,使其能够快速重合闸,... 为提高柔性直流输电系统发生短路故障后高压直流断路器的故障隔离、限流及重合闸恢复能力,在现有直流断路器结构基础上提出一种具有重合闸功能的限流式直流断路器(RCL-HDCB)。RCL-HDCB方案改进了断路器的限流支路,使其能够快速重合闸,依据动作过程及原理进行了参数设计,在PSCAD/EMTDC仿真软件中搭建了基于模块化多电平换流器(modular multilevel converter,MMC)的双端直流输电系统,对RCLHDCB的运行状态进行仿真验证,结果表明该设备在发生短路故障后能够快速有效开断,故障电流也得到了较好的抑制,同时重合闸运行稳定,因此该RCL-HDCB方案对柔直输电系统具有一定的指导意义。 展开更多
关键词 柔直系统故障 限流式直流断路器 故障隔离 重合闸
下载PDF
面向新型电力系统的柔性直流换流器统一控制架构
17
作者 文劲宇 张浩博 +5 位作者 向往 孟沛彧 林卫星 周猛 左文平 程时杰 《中国电机工程学报》 EI CSCD 北大核心 2024年第18期7068-7083,I0003,共17页
新型电力系统的发展对柔性直流输电技术提出了更高需求,随着异构串联型直流换流器拓扑架构的提出,柔直换流器已在拓扑层面实现结构统一。然而,在控制层面,传统柔直换流器控制虽然具备功率解耦控制能力,但交流电压、直流电压和子模块电... 新型电力系统的发展对柔性直流输电技术提出了更高需求,随着异构串联型直流换流器拓扑架构的提出,柔直换流器已在拓扑层面实现结构统一。然而,在控制层面,传统柔直换流器控制虽然具备功率解耦控制能力,但交流电压、直流电压和子模块电容电压之间存在紧密耦合,难以发挥柔直换流器全控型器件运行灵活性高的优势。首先,基于现有直流换流器控制架构,提出控制自由度的概念,并引入调制比的表征方法,构建模块化多电平换流器(modular multilevel converter,MMC)的多自由度控制体系;然后,通过分析MMC换流器内部的电压耦合机理及其与调制比的关系,系统地揭示了现有MMC换流器的各种控制策略之间的关联性,形成具备“功能统一、结构统一”的MMC换流器的4自由度统一控制架构。并针对柔直系统中不同控制目标的MMC换流器分析4自由度控制架构的应用及其控制潜能;最后,在单端MMC物理动模实验系统中对MMC换流器4自由度控制在典型应用场景下的性能进行实验验证。 展开更多
关键词 柔性直流输电 模块化多电平换流器 电压耦合 4自由度控制 调制比 动模实验
下载PDF
用于微波无线输能的高增益柔性天线研究
18
作者 彭文雄 李鑫源 +2 位作者 肖辉 张淮清 刘哲玮 《传感器与微系统》 CSCD 北大核心 2024年第4期57-60,共4页
为克服传统有线供能方式的接入不便问题,提出了一种用于5.8 GHz微波无线输能(MWPT)高增益柔性天线。天线以聚酰亚胺(PI)为基底,采用广义迭代设计方法得到3层圆环结构,并选用共面波导(CPW)方式馈电。此外,为提高天线增益,在天线背面加载... 为克服传统有线供能方式的接入不便问题,提出了一种用于5.8 GHz微波无线输能(MWPT)高增益柔性天线。天线以聚酰亚胺(PI)为基底,采用广义迭代设计方法得到3层圆环结构,并选用共面波导(CPW)方式馈电。此外,为提高天线增益,在天线背面加载空气层和柔性反射板,并对天线性能进行了测试。测量结果显示:该天线在频率5.8 GHz处的峰值增益为9.51 dBi;当天线弯曲在曲率半径为85,60,45 mm时,增益始终保持在8.89 dBi以上,S_(11)幅值始终小于-10 dB。最后,通过微波无线输能实验测得该天线最大能量捕获效率可达71.3%,在弯曲状态下也能保持59%以上的捕获效率。该天线的高增益、高能量捕获效率以及稳定性证明了其在微波无线输能中具有潜在的应用价值。 展开更多
关键词 柔性天线 高增益 微波无线输能 能量捕获效率
下载PDF
低频电压下XLPE电树枝生长及局部放电特性
19
作者 刘云鹏 尹子澳 +3 位作者 刘贺晨 林浩凡 刘黎 赵家莹 《绝缘材料》 CAS 北大核心 2024年第4期66-71,共6页
低频电缆作为柔性低频交流输电系统中的关键设备,其绝缘介质在低频电压下的特性对电缆的设计和运行具有重要意义。为了研究低频电压下交联聚乙烯(XLPE)电树枝的生长及局部放电特性,设计并搭建了不同频率下电树枝生长实时观测和局部放电... 低频电缆作为柔性低频交流输电系统中的关键设备,其绝缘介质在低频电压下的特性对电缆的设计和运行具有重要意义。为了研究低频电压下交联聚乙烯(XLPE)电树枝的生长及局部放电特性,设计并搭建了不同频率下电树枝生长实时观测和局部放电同步测量系统,探究了XLPE试样分别在20、30、40、50 Hz频率下电树枝的引发、生长及局部放电特性。结果表明:电压频率对XLPE电树枝生长及局部放电特性的影响有明显规律性。在20~50 Hz范围内,随着频率的降低,XLPE的起树电压略有升高,但电树枝生长速度加快,损伤面积增加,局部放电量和放电次数增大,放电相位分布基本不变。 展开更多
关键词 交联聚乙烯 电树枝 局部放电 柔性低频输电
下载PDF
基于二极管整流器的双极型复合式海上换流站及其控制策略
20
作者 李瑞 郑涛 +2 位作者 俞露杰 索之闻 徐殿国 《电网技术》 EI CSCD 北大核心 2024年第3期1190-1201,共12页
为提高海上换流站的紧凑型性并降低换流站一次性投入成本,西门子公司提出了基于二极管整流器(diode rectifier,DR)的高压直流输电技术,在此基础上,国内外学者对其控制策略及各种串并联拓扑进行了研究,但仍存在结构复杂、可行性差、运行... 为提高海上换流站的紧凑型性并降低换流站一次性投入成本,西门子公司提出了基于二极管整流器(diode rectifier,DR)的高压直流输电技术,在此基础上,国内外学者对其控制策略及各种串并联拓扑进行了研究,但仍存在结构复杂、可行性差、运行灵活性低等问题。为此,提出了基于二极管整流器的双极型复合式海上换流站拓扑,正负极分别采用模块化多电平换流器(modularmultilevelconverter,MMC)和DR,以充分利用MMC灵活可控和DR体积小、成本低、可靠性高的优点。为降低直流电缆输电损耗,提出了复合式换流站正负极功率平衡控制,将接地极电流控制在零附近,提高了输电效率,可将高压直流电缆所产生的损耗降低67.7%。设计了限功率控制,在发生直流非对称故障期间通过低速通信,可主动对风电场发出功率进行限制,防止了换流站过电流风险,提高了系统可靠性。最后通过PSCAD/EMTDC仿真分析对所提拓扑及其控制策略进行了可行性验证。 展开更多
关键词 海上风电 柔性直流输电 复合式换流站 二极管整流器 直流故障保护
下载PDF
上一页 1 2 60 下一页 到第
使用帮助 返回顶部