This paper is about the application of PLC (Model S5 135U made by Siemens) in the overhead crane.It is mainly about the working principles and application of PLC Model S5 135U.
Overhead lines are the backbone of the electrical power transmission.Contrary to the distributions networks,the transmission system consists only in exceptional cases of longer cable lines.Typical exceptions are conne...Overhead lines are the backbone of the electrical power transmission.Contrary to the distributions networks,the transmission system consists only in exceptional cases of longer cable lines.Typical exceptions are connections of cavern power plants,approaches to airports or bird sanctuaries and lines in urban centres.In the majority of cases,an overhead line is the most economic and practicable solution for the energy transmission.In tourism regions,an overhead line will be seen as impairment of nature or landscape and so the approval chain and procedure is in most countries long-winded and circumstantial.At the other hand,the energy consumption in Europe is growing and the volatility of transmitted power is also increasing during the last decade caused by the opening of the electric energy market.This opening process leads to a stopping of the enlargement of the interoperation network and to a minimisation of the maintenance of existing lines.Today the network operates more often at the limit of the equipment and the small and large-areas disturbances and blackouts are increasing.The operators of transmission lines are forced to ensure the electrical power supply and so they have to improve the reliability of the network.One solution is to monitor the critical(heavy loaded)overhead lines.For example,with the knowledge of the thermal condition,the risk of unexpected outages can be reduced.Today several monitoring systems are available on the market.They differ in the principle and techniques of the condition evaluation.The three most interesting output variables are the line temperature,the capable transmission power and the actual sag of the investigated section.In this paper an overview of existing overhead line monitoring system and also an outline over the usage and benefit for the application will be given.Thermal monitoring is one technique to improve the reliability of the network and for increasing or optimising the capable transmission power.展开更多
There are two major protective methods against lightning outages on overhead distribution lines.One is a surge arrester,and the other is an overhead ground wire.The surge arresters have rather constant effect regardle...There are two major protective methods against lightning outages on overhead distribution lines.One is a surge arrester,and the other is an overhead ground wire.The surge arresters have rather constant effect regardless of the cause of the lightning outage.On the other hand,the effect of an overhead ground wire is quite different in two major causes,the direct lightning hit and the induced overvoltage.It is sufficient to provide surge arresters with an interval of 300 m for protection against the induced overvoltage caused by the nearby lightning stroke.Use of an overhead ground wire together with surge arresters is effective for lightning protection against the direct lightning hit to a distribution line.Puncture of surge arresters is the popular outage when the outage caused by the insulation break decreases sufficiently.Also,the existence of nearby trees leads to the line break due to the side flash from a tree.Advanced lightning protection equipment with ZnO arrester components is popular in Japan.Modeling of a pole transformer and application of an electromagnetic analysis method,such as FDTD method,to surge phenomena is considerably advanced.展开更多
This work is carried out to predict the special distribution of electric field induced by multi-circuit intersecting overhead high-voltage (HV) transmission lines (TLs) within a large range without any expensive and t...This work is carried out to predict the special distribution of electric field induced by multi-circuit intersecting overhead high-voltage (HV) transmission lines (TLs) within a large range without any expensive and time-consuming computation. The two main parts of the presented methodology are 1) setting up a three-dimensional (3D) model to calculate the electric field based on combining ca- tenary equations with charge simulation method and 2) calculating the hybrid electric field excited by multi-circuit intersecting TLs using coordinate transformation and superposition technique. Examples of different TLs configurations, including a 220 kV single-circuit hori- zontally configured TLs, a 500 kV single-circuit triangularly configured TLs and a combination of the 220 kV TLs and the 550 kV TLs, are illustrated to verify the validity of this methodology. A more complicatal configurations, including a 500 kV double-circuit TLs and two 220 kV single-circuit horizontally configured TLs, are also calculated. Conclusions were drawn from the simulation: 1) The presented 3D model outperforms 2D models in describing the electric field distribution generated by practical HV TLs with sag and span. 2) Coordinate trans- formation and superposition technique considerably simplify the electric field computation for multi-circuit TLs configurations, which makes it possible to deal with complex engineering problems. 3) The electric field in the area covered by multiple intersecting overhead TLs is distorted and the hybrid electric field strength in some partial region increases so sharply that it might exceed the admissible value. 4) The configuration parameters of the TLs and the spatial configuration of multi-circuit TLs, for instance, the height of TLs, the length of span and the intersection angle of multiple circuits, influence the strength and the distribution of hybrid electric field. The influence regularities sum- marized in this paper can be referred by future TL designs to meet the electromagnetic environmental protection regulations.展开更多
Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have prove...Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have proven their operational reliability and functional assurance.In the past,cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables.New developments of high voltage XLPE cables make it possible to use this technology for EHV level applications in transmission networks.Within this paper,mixed network configurations,consisting of overhead lines and high voltage cables,are investigated.An exemplary EHV transmission line with a total length of about 100 km,which is quite typical for Central Europe,has been studied.Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice.The length of the cable sections are ranging from several kilometers up to lengths of 100 km.In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts.A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system.Numerical programs like ATP/EMTP have been used for these simulations.Peak values and wave shapes of the transient voltage stress have been evaluated,based on different systems and within possible combinations.In respect of the insulation coordination and transient stress at network nodes,the voltage-time trends are also analyzed.The combination of high voltage overhead and cable transmission systems,especially such with lengths of more than about 50 km,are making tightened and extended demands to the network design,to the operational management and of course to the network protection also.As an output of this investigations,the results might influence the strategy in running this new type of combined transmission systems.展开更多
文摘This paper is about the application of PLC (Model S5 135U made by Siemens) in the overhead crane.It is mainly about the working principles and application of PLC Model S5 135U.
基金Supported by National Natural Science Foundation of China （61325017, 11372144）, and the National Science and Technology Pillar Program of China （2013BAF07B03）
文摘Overhead lines are the backbone of the electrical power transmission.Contrary to the distributions networks,the transmission system consists only in exceptional cases of longer cable lines.Typical exceptions are connections of cavern power plants,approaches to airports or bird sanctuaries and lines in urban centres.In the majority of cases,an overhead line is the most economic and practicable solution for the energy transmission.In tourism regions,an overhead line will be seen as impairment of nature or landscape and so the approval chain and procedure is in most countries long-winded and circumstantial.At the other hand,the energy consumption in Europe is growing and the volatility of transmitted power is also increasing during the last decade caused by the opening of the electric energy market.This opening process leads to a stopping of the enlargement of the interoperation network and to a minimisation of the maintenance of existing lines.Today the network operates more often at the limit of the equipment and the small and large-areas disturbances and blackouts are increasing.The operators of transmission lines are forced to ensure the electrical power supply and so they have to improve the reliability of the network.One solution is to monitor the critical(heavy loaded)overhead lines.For example,with the knowledge of the thermal condition,the risk of unexpected outages can be reduced.Today several monitoring systems are available on the market.They differ in the principle and techniques of the condition evaluation.The three most interesting output variables are the line temperature,the capable transmission power and the actual sag of the investigated section.In this paper an overview of existing overhead line monitoring system and also an outline over the usage and benefit for the application will be given.Thermal monitoring is one technique to improve the reliability of the network and for increasing or optimising the capable transmission power.
文摘There are two major protective methods against lightning outages on overhead distribution lines.One is a surge arrester,and the other is an overhead ground wire.The surge arresters have rather constant effect regardless of the cause of the lightning outage.On the other hand,the effect of an overhead ground wire is quite different in two major causes,the direct lightning hit and the induced overvoltage.It is sufficient to provide surge arresters with an interval of 300 m for protection against the induced overvoltage caused by the nearby lightning stroke.Use of an overhead ground wire together with surge arresters is effective for lightning protection against the direct lightning hit to a distribution line.Puncture of surge arresters is the popular outage when the outage caused by the insulation break decreases sufficiently.Also,the existence of nearby trees leads to the line break due to the side flash from a tree.Advanced lightning protection equipment with ZnO arrester components is popular in Japan.Modeling of a pole transformer and application of an electromagnetic analysis method,such as FDTD method,to surge phenomena is considerably advanced.
基金Project supported by Scientific Research Foundation of State Key Laboratory of Power Transmission Equipment ＆ System Security and New Technology （2007DA1051271 2204）, Natural Science Foundation of Chongqing Municipality （cstc201 ljjA20009）.
文摘This work is carried out to predict the special distribution of electric field induced by multi-circuit intersecting overhead high-voltage (HV) transmission lines (TLs) within a large range without any expensive and time-consuming computation. The two main parts of the presented methodology are 1) setting up a three-dimensional (3D) model to calculate the electric field based on combining ca- tenary equations with charge simulation method and 2) calculating the hybrid electric field excited by multi-circuit intersecting TLs using coordinate transformation and superposition technique. Examples of different TLs configurations, including a 220 kV single-circuit hori- zontally configured TLs, a 500 kV single-circuit triangularly configured TLs and a combination of the 220 kV TLs and the 550 kV TLs, are illustrated to verify the validity of this methodology. A more complicatal configurations, including a 500 kV double-circuit TLs and two 220 kV single-circuit horizontally configured TLs, are also calculated. Conclusions were drawn from the simulation: 1) The presented 3D model outperforms 2D models in describing the electric field distribution generated by practical HV TLs with sag and span. 2) Coordinate trans- formation and superposition technique considerably simplify the electric field computation for multi-circuit TLs configurations, which makes it possible to deal with complex engineering problems. 3) The electric field in the area covered by multiple intersecting overhead TLs is distorted and the hybrid electric field strength in some partial region increases so sharply that it might exceed the admissible value. 4) The configuration parameters of the TLs and the spatial configuration of multi-circuit TLs, for instance, the height of TLs, the length of span and the intersection angle of multiple circuits, influence the strength and the distribution of hybrid electric field. The influence regularities sum- marized in this paper can be referred by future TL designs to meet the electromagnetic environmental protection regulations.
文摘Electrical power transmission is dominated by overhead line systems at present.This is mainly based on more than hundred years of experience of utilities in running overhead lines.Furthermore,overhead lines have proven their operational reliability and functional assurance.In the past,cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables.New developments of high voltage XLPE cables make it possible to use this technology for EHV level applications in transmission networks.Within this paper,mixed network configurations,consisting of overhead lines and high voltage cables,are investigated.An exemplary EHV transmission line with a total length of about 100 km,which is quite typical for Central Europe,has been studied.Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice.The length of the cable sections are ranging from several kilometers up to lengths of 100 km.In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts.A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system.Numerical programs like ATP/EMTP have been used for these simulations.Peak values and wave shapes of the transient voltage stress have been evaluated,based on different systems and within possible combinations.In respect of the insulation coordination and transient stress at network nodes,the voltage-time trends are also analyzed.The combination of high voltage overhead and cable transmission systems,especially such with lengths of more than about 50 km,are making tightened and extended demands to the network design,to the operational management and of course to the network protection also.As an output of this investigations,the results might influence the strategy in running this new type of combined transmission systems.
文摘研究受限空间内过头作业人员疲劳特征,以避免疲劳累积和降低事故风险。设计了典型受限空间内过头作业试验,测量20名被试在不同受限空间高度(120 cm、140 cm)和不同工作面(侧面、顶面、正面)下的表面肌电(Surface Electromyogram,sEMG)信号和心率变异性(Heart Rate Variability,HRV)信号,记录主观疲劳评分,并对数据进行分析。结果表明:受限空间内过头作业疲劳累积明显;右肩膀和右前臂主观疲劳评分最高;左上斜方肌、右上斜方肌、右中三角肌、右冈上肌、右冈下肌和右肱桡肌中位频率(Median Frequency,MF)下降显著,右中三角肌MF下降幅度最大;相邻RR间期均值(RR mean)降低,低频成分(Low Frequency,LF)和低频高频比值(Ratio of Low Frequency to High Frequency,LF/HF)均上升;与120 cm高度相比,140 cm高度下全身及5个身体部位主观疲劳评分更高,6个肌群MF下降斜率更大,RR mean下降幅度以及LF、LF/HF上升幅度更大;工作面对主观疲劳评分、各肌群MF及HRV指标影响不显著,但正面工作面除右肱桡肌外5个肌群均疲劳累积显著,侧面和顶面工作面右上斜方肌、右中三角肌和右冈上肌3个肌群疲劳累积显著。
文摘水声网络(underwater acoustic network,UAN)具有长传播时延、高误码率、半双工通信等特性,这些特性严重影响了UAN中数据的可靠传输。而在线喷泉码具有在线控制、编解码复杂度低、码率自适应等诸多优势,在线喷泉码适合于保障UAN中数据的可靠传输。针对递归与限制反馈的在线喷泉码(recursive OFC with limited feedback,ROFC-LF)存在不理想覆盖和4元环问题导致略高的开销和频繁的反馈,提出适用于UAN的基于优先级与可Zigzag解码的ROFC-LF(priority-based and zigzag-decodable ROFC-LF,P-ZROFC-LF)。P-ZROFC-LF在建立阶段选取具有最高优先级的原始包进行编码直至所有原始包均参与编码。同时,引入可Zigzag解码编码,将无用编码包进行移位异或转换为有用编码包来提高解码性能。通过随机图理论,分析P-ZROFC-LF所需编码包数与原始包数之间的关系。理论分析与仿真结果表明,与大部分在线喷泉码相比,P-ZROFC-LF显著提高了反馈和开销性能。其中P-ZROFC-LF相比于ROFC-LF的反馈和开销分别减少了18%和0.0176,更适用于UAN。
