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
An improved method for calculating the corona power loss and the ground-level electric field on HVAC transmission lines induced by corona is proposed.Based on a charge simulation method combined with a method of succe...An improved method for calculating the corona power loss and the ground-level electric field on HVAC transmission lines induced by corona is proposed.Based on a charge simulation method combined with a method of successive images,the proposed method has the number and location of the simulated charges not arbitrary.When the surface electric field of a conductor exceeds the onset value,charges are emitted from corona into the space around,and the space ions and the surface charges on each sub-conductor are simulated by using the images of the other sub-conductors.The displacements of the space ions are calculated at every time step during corona periods in both the positive and the negative half cycles.Several examples are calculated by using the proposed method,and the calculated electric field at the ground level and the corona power loss agree well with previous measurements.The results show that simulating 12 charges in each conductor during 600 time steps in one cycle takes less time while guarantees the accuracy.The corona discharge from a 220 kV transmission line enhances slightly(less than 2%) the electric field at the ground level,but this effect is little from a 500 kV line.The improved method is a good compromise between the time cost and the accuracy of calculation.展开更多
在电力系统中,单独依赖红外或可见光图像不足以全面评估输电线路状况,图像融合能够结合两类图像的优势,为后续输电线路目标检测和三维建模等提供便利。为增强输电线路图像融合效果,提出一种基于多分支特征分解的网络用于红外和可见光图...在电力系统中,单独依赖红外或可见光图像不足以全面评估输电线路状况,图像融合能够结合两类图像的优势,为后续输电线路目标检测和三维建模等提供便利。为增强输电线路图像融合效果,提出一种基于多分支特征分解的网络用于红外和可见光图像融合。该网络在编码器部分改进特征图分解结构,在分解基础和细节特征图的基础上,保留原特征图,随后在多分支特征信息融合模块中,结合不同图像信息特点进行图像加权融合,随后在解码器中使用双维注意力增强模块整合特征,生成融合图像。在输电线路数据集以及TNO数据集上,与现有方法在8种客观评价指标上比较,结果表明所提方法在两个数据集的各项性能指标上取得优异的性能,其中在交叉熵(entropy,EN)、标准差(standard deviation,SD)、差异相关和(sum of the correlations of differences,SCD)、结构相似性(structural similarity index measure,SSIM)4个指标上分别为7.26、62.04、1.53和0.93,达到最高值,并且实际融合效果图显示所提方法能够有效增强输电线路图像的红外重点信息与可见光细节信息。展开更多
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.
基金supported by National Basic Research Program of China(973 Program)(2011CB209404)
文摘An improved method for calculating the corona power loss and the ground-level electric field on HVAC transmission lines induced by corona is proposed.Based on a charge simulation method combined with a method of successive images,the proposed method has the number and location of the simulated charges not arbitrary.When the surface electric field of a conductor exceeds the onset value,charges are emitted from corona into the space around,and the space ions and the surface charges on each sub-conductor are simulated by using the images of the other sub-conductors.The displacements of the space ions are calculated at every time step during corona periods in both the positive and the negative half cycles.Several examples are calculated by using the proposed method,and the calculated electric field at the ground level and the corona power loss agree well with previous measurements.The results show that simulating 12 charges in each conductor during 600 time steps in one cycle takes less time while guarantees the accuracy.The corona discharge from a 220 kV transmission line enhances slightly(less than 2%) the electric field at the ground level,but this effect is little from a 500 kV line.The improved method is a good compromise between the time cost and the accuracy of calculation.
文摘在电力系统中,单独依赖红外或可见光图像不足以全面评估输电线路状况,图像融合能够结合两类图像的优势,为后续输电线路目标检测和三维建模等提供便利。为增强输电线路图像融合效果,提出一种基于多分支特征分解的网络用于红外和可见光图像融合。该网络在编码器部分改进特征图分解结构,在分解基础和细节特征图的基础上,保留原特征图,随后在多分支特征信息融合模块中,结合不同图像信息特点进行图像加权融合,随后在解码器中使用双维注意力增强模块整合特征,生成融合图像。在输电线路数据集以及TNO数据集上,与现有方法在8种客观评价指标上比较,结果表明所提方法在两个数据集的各项性能指标上取得优异的性能,其中在交叉熵(entropy,EN)、标准差(standard deviation,SD)、差异相关和(sum of the correlations of differences,SCD)、结构相似性(structural similarity index measure,SSIM)4个指标上分别为7.26、62.04、1.53和0.93,达到最高值,并且实际融合效果图显示所提方法能够有效增强输电线路图像的红外重点信息与可见光细节信息。
