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Search Results: 1 - 10 of 3764 matches for " traction current divert "
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高铁站内绝缘节烧损解决方案
A solution for burning damage to insulation joints in high-speed railway stations

毕红军,丁志东,石先明,刘畅
- , 2015, DOI: 10.11860/j.issn.1673-0291.2015.03.002
Abstract: 摘要 为了解决高速铁路轨道机械绝缘节的烧损问题,并优化高铁站内回流疏导方案,根据对杭长线长沙南站内绝缘节电位差的实地测试数据,从机械绝缘节的设置点、牵引电流回流疏导设置等方面,提出一种高速铁路站内机械绝缘节烧损问题的解决方案.分析了该方案的可行性原理,结合现场测试数据进行了验证.试验数据表明:提出的方案能够有效降低机械绝缘节两端的电位差,改善机械绝缘节烧损问题.
Study on Distribution Coefficient of Traction Return Current in High-Speed Railway  [PDF]
Wen Huang, Zhengyou He, Zhengyou He, Haitao Hu, Qi Wang
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B238
Abstract:

The distribution coefficient of return current network is an important method to decrease the rail potential. In order to resolve the problem of high rail potential in high-speed railway based on EN50122-1 and Pr EN50170 the distribution coefficient of longitudinal traction return current conductors is calculated through changing the interval of transverse connection. Based on field data and theoretical analysis, the parameters of longitudinal traction return current conductors are calculated. Results indicate that the best distance of the transverse connection is 400 m600 m.

Study on Electromagnetic Transient Condition of EMU Passing by Phase-separation with Electric Load in High-speed Railway  [PDF]
Xiaoxu Guo, Jianzhong Wei, Long Xu, Shibin Gao, Zhengqing Han
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B202
Abstract:

Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.

An Integrated Drive for Two PMSMs Involved Automotive Applications and Development of Current Reference Expanded Two Arm Modulation Technique  [PDF]
V. Krishnakumar, V. Kamaraj, C. Adrien Perianayagam
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78155
Abstract: A five leg inverter (FLI) control is incorporated to drive two independent rated permanent magnet synchronous motors (PMSMs) for automotive applications. Literature evidences many attempts of employing the FLI for controlling two general purpose/special motors, where variety of modulation techniques has been practiced for performance enhancement. Also in these cases one leg of inverter is common to both the motors. The expanded two arm modulation (ETAM) has been generally engaged in FLI. In ETAM the percentage voltage utilization factor (VUF) is calculated based on “αmax”, where “αmax” is the maximum modulation index and equal to?and hence it restricts the VUF to 50%. This makes the FLI drives to use the dc link in inefficient way, which is due to the fact that conventional ETAM works with voltage reference. This paper modifies the ETAM in an ingenious way to improve the VUF further through current reference. In addition, the developed current reference expanded two arm modulation (CRETAM) minimizes the current harmonics and torque ripple as well. A detailed comparison of the CRETAM with the conventional ETAM and the competent digital counterpart, space vector pulse width modulation (SVPWM), is also presented. The enhancement in VUF, torque ripple minimization and current total harmonic distortion (THD) reduction are found in the MATLAB based simulation results.
The Effect of Traction Position in Cervical Traction Therapy Based on Dynamic Simulation Models  [PDF]
Lawrence K. F. Wong, Zhiwei Luo, Nobuyuki Kurusu
Journal of Biomedical Science and Engineering (JBiSE) , 2017, DOI: 10.4236/jbise.2017.105019
Abstract: This study describes the development of a cervical traction therapy simulation model that evaluates two types of the traction positions, namely the sitting position and the inclined position. An anatomically correct human skeleton model and two mechanical traction device models were constructed in simulations using a physics engine. The anterior and posterior intervertebral separations were measured at both positions with a series of traction forces (60N to 200N) and traction angles (10° to 40°). The result suggested that the sitting position caused the subject to lean forward and as a result led to excessive anterior compression when traction angle is over 20 degrees. The inclined position creates greater intervertebral separations on both the anterior and posterior sides than the sitting position. This suggests that the inclined position may be more effective in increasing intervertebral separation than the sitting position.
Treatment of Vertically Unstable Sacral Fractures with Pelvic External Fixation and Skeletal Traction  [PDF]
Xueyuan Wu, Hongbin Zhu, Heng Du, Wei Ma, Chihua Guo
Surgical Science (SS) , 2013, DOI: 10.4236/ss.2013.44043
Abstract:

Objective: To determine the efficacy in treatment of vertically unstable sacral fractures with pelvic external fixation and skeletal traction. Patients and Methods: The pelvic external fixation and skeletal traction were applied on 12 cases of vertically unstable sacral fracture (eight males and four females, at age of 19 - 52 years, mean 35.2 years) including two cases of Denis Zone I, nine of Zone II, and one of Zone III. All patients were treated with the pelvic external fixation, and pre- and post-operational longitudinal skeletal traction. Results: The mean operation time, skeletal traction time, skeletal traction removal time and full weight bearing time were 38 min, 4.5 weeks, 8.5 weeks, and 10.3 weeks respectively. All these patients were followed up for 12 - 36 months (average, 22.5 months), which showed no associated complication. The function results were rated as excellent in four cases, good in six and fair in two, with a mean score of 84.4 points, according to Majeed scoring system. Conclusion: The anterior pelvic external fixation with continuous skeletal traction can reliably restore and stabilize the vertically unstable sacrum fracture with excellent functional and radiographic outcomes. It is an ideal method to treat unstably vertical sacral fracture.

SEUDOAINHUM SECUNDARIO A TRICOTILOMANIA: REPORTE DE CASO Y REVISIóN DE L LITERATURA
ARISTIZáBAL F.,LILIANA; ALMARIO A,PIEDAD;
Revista Med , 2007,
Abstract: we are presenting the case of 62 years old male. the patient presented during the last three months with a painful circunferential crease in the fingertips associated with areas of alopecia by-temporal presenting hair with irregular borders and different length. without other clinical features showing, the patient appears to be anxious with permanent manipulation of the hairy leather. skin biopsy did not show any changes, however, the hairy leather showed tricomalacia. because of the clinical features, the diagnosis was seudoainhum, secondary to hair traction. other etiologies were discarded. this case notice the importance of the skin as a marker for emotional distress.
城市轨道交通交流牵引供电系统及其关键技术
Industrial Frequency Single-Phase AC Traction Power Supply System and Its Key Technologies for Urban Rail Transit

李群湛
- , 2015,
Abstract: 摘要: 在地铁、轻轨等城市轨道交通中,为了避免现行直流牵引供电系统的迷流,同时发挥其无分相的优势,提出并研究了一种交流牵引供电系统.该系统由主变电所(MSS)和电缆牵引网(CTN)构成,主变电所由单相主牵引变压器(MTT)和负序补偿装置(NCD)组合而成,电缆牵引网由双芯电缆(DCC)、牵引变压器(TT)和接触网(OCS)、钢轨(R)等构成.讨论了该系统的3项关键技术:电缆牵引网的供电原理,等效电路和输电能力,电缆与接触网的匹配技术,接触网电压等级选择等;牵引网分段供电技术,牵引网供电状态辨识方法,分布式保护与集中式保护方案等;单条线路主变电所供电方案,2条及以上线路共用主变电所的供电方案.该系统技术性能优良,经济性好,可靠性高,为地铁、轻轨等城市轨道交通提供了新的、更好的选择.
Abstract: To avoid stray current and maintain the benefit of no phase-split in the DC traction power supply system, an AC traction power supply system was proposed for the urban public transport such as metro and light rail transit. The proposed system consists of main substation (MSS) and cable traction network (CTN). MSS includes a single-phase main traction transformer (MTT) and a negative sequence compensation device (NCD), while CTN includes double-core cables (DCC), traction transformers (TT), overhead catenary system (OCS), rails (R), etc. Three key techniques of the proposed system were discussed. First, power supply principle, equivalent circuit and transmission ability of CNT were introduced and cable-catenary matching technique, catenary voltage level selection were discussed. Second, the segmentation technology, status identification method for traction power supply network, distributed and centralized protection schemes, etc. were discussed. Third, single-line main substation supply scheme, and two or more lines shared main substation scheme were presented. Given that the excellent technical performance, good economy and high reliability of the proposed system, it provides a new alternative for metro and urban rail transit power supply system
高速铁路牵引回流系统建模分析
Modeling analysis of high speed railway traction return current system

魏巍,刘炜,叶小雯
WEI Wei
, LIU Wei, YE Xiaowen

- , 2018,
Abstract: 高速铁路牵引回流分布复杂,有必要对其进行精确的建模分析。采用平行多导体传输线理论,搭建统一的牵引网数学模型,实现针对不同空间分布形式的牵引网阻抗和导纳的计算。运用埋地裸导线法对综合地线进行建模,弥补等效接地电阻法不能计算导线电流的缺点,且计及综合地线与其他导线间的耦合,研究不同回流导线中的电流分布比例,并与实测数据进行对比,验证埋地裸导线建模法及牵引网链式网络潮流算法的准确性,并探讨回流测试方案。
The distribution of high speed railway traction return current is complex. It is necessary to carry out its accurate analysis of the model. Based on the parallel multi-conductor transmission line theory, this paper sets up a unified mathematical model of the traction network and realizes the impedance calculation for different forms of traction network. With the method of buried bare wires, the modeling of integrated grounding wire makes up for the shortcomings of grounding resistance equivalent method which cannot calculate wire current, and takes the coupling between the integrated grounding wire and the other wire into account. The distribution proportion of current in different return wires is figured out and compared with the measured return current ratio. In this way, the accuracy of the buried bare wires method and the chain network flow algorithm are verified. The return current test schemes are explored
Investigation of Power Factor Behavior in AC Railway System Based on Special Traction Transformers  [PDF]
Mohsen Kalantari, Mohammad Javad Sadeghi, Seyed Saeed Fazel, Siamak Farshad
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.211081
Abstract: The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unbalance loading are investigated simultaneously for electrical railway systems. Special traction transformers (i.e. single-phase, V/V, Wye-Delta, Scott, and Le Blanc) are used between the utility grid and the traction load. For analysis, different defini-tions of power factors are considered, which are presented by IEEE Std.1459. The detailed simulation study is made with MATLAB/SIMULINK program to represent the impacts of harmonic components and unbalance loading on the power factor behavior in the Electrical Railway systems.
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