The electromagnetic losses of submarine cables are mainly caused by the metal shielding layer to prevent the water tree effect and the armor layer that strengthens the strength of the submarine cables.While these loss...The electromagnetic losses of submarine cables are mainly caused by the metal shielding layer to prevent the water tree effect and the armor layer that strengthens the strength of the submarine cables.While these losses cause the temperature of submarine cable to rise,and temperature variation will in turn change the conductivity of its metal layer material.In this paper,the electric-magnetic-thermal multi-physical field coupling of the electromagnetic loss variation of the submarine cable is realized by establishing a full coupling system containing Fourier’s law and Maxwell-Ampère’s Law for the photoelectric composite submarine cable.The multi-physical field coupling model is solved and analyzed by using the finite elementmethod.Firstly,the loss of each layer of the optoelectronic composite submarine cable is analyzed,and the lossof eachlayer of the submarine cable and themainfactors leading to the loss of the submarine cable are given.Secondly,the influence of environmental temperature,ampacity and armor layer on the electromagnetic loss of submarine cables is studied,and the main operating factors affecting the electromagnetic loss of submarine cables are summarized.The research shows that the influence of ambient temperature can be ignored,and the loss of shielding layer and armor layer increases with the increase of ampacity,but the impact of shielding layer loss is greater.Finally,this paper studies the electromagnetic loss of each metal layer of the submarine cable and the influence of the laying spacing on the electromagnetic loss.The research results show that the two ways of improving the conductivity of the armor layer and reducing the relative permeability of the armor layer can effectively reduce the loss of each metal layer in the cable structure and increase the current carrying capacity when the tensile strength of the armor layer meets the requirements for single-core and threecore photoelectric composite submarine cables laid horizontally.At the same time,increasing the laying spacing will increase the loss,but it can improve the overall current carrying capacity of the cable.The research in this paper provides a theoretical basis for the design of submarine cable carrying capacity,and also provides a reference for the optimization design of submarine cable structures.展开更多
Power transmission across the sea is an important part of global energy interconnection(GEI).To support the construction of GEI and to serve the needs of future clean energy trans-sea transportation and offshore wind ...Power transmission across the sea is an important part of global energy interconnection(GEI).To support the construction of GEI and to serve the needs of future clean energy trans-sea transportation and offshore wind power development,this study a)analyzes the requirements of the GEI backbone network pertaining to direct current(DC)submarine cable technology,and b)defines the key technical and economic indices of ultrahigh-voltage direct current(UHVDC)submarine cable based on theoretical computations.The research is based on the thermoelectric coupling model and the finite element method.It is shown that the dielectric strength of the insulating materials of the±800 kV~±1100 kV/4000 MW^12000 MW UHVDC submarine cable(extrusion insulation)should be not less than 43~65 kV/mm,while the heat resistance is not less than 110°C.As the cost of submarine cable is 5~10 times higher than that of the overhead line,the project investment need to be decreased to a level within the economical carrying capacity to guarantee extensive applicability of the HVDC submarine cable technology.展开更多
Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to ...Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to submarine cables are summarized, which include seabed displacement induced by fault movement, submarine landslides and seabed soil liquefaction, etc. The damage is similar to damage observed to buried pipelines following land earthquakes. The Hengchun earthquake of Dec. 26, 2006 is used as a case study. The M7.2 earthquake occurred in the South China Sea at 20：26 Beijing Time, and caused 14 international submarine cables to sever and break. The results show that the proposed method predicts damage similar to that observed in the Hengchun earthquake. Based on parametric studies of the influence of the water depth and the magnitude of the submarine earthquake, countermeasures to prevent damage to submarine cables are proposed.展开更多
Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a ...Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a distributed measurement system for in-situ soil moisture content （SM-DTS） is introduced.The system is based on carbon-fiber heated cable （CFHC） technology that has been developed to enhancethe measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristicvalue （Tt） can be defined from temperatureetime curves. A relationship among Tt, soil thermalimpedance coefficient and soil moisture content is then established in laboratory. The feasibility of theSM-DTS technology to provide distributed measurements of in-situ soil moisture content is verifiedthrough field tests. The research reported herein indicates that the proposed SM-DTS is capable ofmeasuring in-situ soil moisture content over long distances and large areas.展开更多
海底电缆作为各类海上平台能源供给的生命线,一旦发生故障将产生巨大的经济及战略影响,准确预测海底电缆运行状态有助于提前把握其运行风险,从而实现预防性维护。在充分挖掘海底电缆运维数据中的动、静态特征的基础上,提出了一种基于注...海底电缆作为各类海上平台能源供给的生命线,一旦发生故障将产生巨大的经济及战略影响,准确预测海底电缆运行状态有助于提前把握其运行风险,从而实现预防性维护。在充分挖掘海底电缆运维数据中的动、静态特征的基础上,提出了一种基于注意力机制和卷积神经网络-门控循环神经网络(convolutional neural networks-gated recurrent unit, CNN-GRU)海底电缆运行状态预测方法。首先,考虑在线监测、巡检指标、静态试验三类关键影响因素,建立海底电缆运行状态评估指标体系;然后,基于改进层次分析法及多层次变权评估思想构建海底电缆运行状态评估模型;最后,建立基于注意力机制和CNN-GRU组合神经网络模型,将历史运行参数及状态量化结果作为输入特征参量,实现海底电缆运行状态的演化趋势预测。算例分析表明,所提方法可有效预测海底电缆的运行状态,平均百分数误差低至1.04%,与全连接神经网络、CNN、CNN-长短期记忆神经网络(long short term memory, LSTM)等算法相比均具备更优的预测精度。展开更多
基金supported in part by the Science and Technology Projects of China Southern PowerGrid Corporation(037700KK52220011)the China Postdoctoral Science Foundation(2019M653631)+2 种基金Key R&D Plan of Shaanxi(2021GY-320,2021GY-306,2020ZDLGY09-10)Xi’an Science and Technology Project(22GXFW0039)the Innovation Capability Support Program of Shaanxi Province(Program No.2022KJXX-41).
文摘The electromagnetic losses of submarine cables are mainly caused by the metal shielding layer to prevent the water tree effect and the armor layer that strengthens the strength of the submarine cables.While these losses cause the temperature of submarine cable to rise,and temperature variation will in turn change the conductivity of its metal layer material.In this paper,the electric-magnetic-thermal multi-physical field coupling of the electromagnetic loss variation of the submarine cable is realized by establishing a full coupling system containing Fourier’s law and Maxwell-Ampère’s Law for the photoelectric composite submarine cable.The multi-physical field coupling model is solved and analyzed by using the finite elementmethod.Firstly,the loss of each layer of the optoelectronic composite submarine cable is analyzed,and the lossof eachlayer of the submarine cable and themainfactors leading to the loss of the submarine cable are given.Secondly,the influence of environmental temperature,ampacity and armor layer on the electromagnetic loss of submarine cables is studied,and the main operating factors affecting the electromagnetic loss of submarine cables are summarized.The research shows that the influence of ambient temperature can be ignored,and the loss of shielding layer and armor layer increases with the increase of ampacity,but the impact of shielding layer loss is greater.Finally,this paper studies the electromagnetic loss of each metal layer of the submarine cable and the influence of the laying spacing on the electromagnetic loss.The research results show that the two ways of improving the conductivity of the armor layer and reducing the relative permeability of the armor layer can effectively reduce the loss of each metal layer in the cable structure and increase the current carrying capacity when the tensile strength of the armor layer meets the requirements for single-core and threecore photoelectric composite submarine cables laid horizontally.At the same time,increasing the laying spacing will increase the loss,but it can improve the overall current carrying capacity of the cable.The research in this paper provides a theoretical basis for the design of submarine cable carrying capacity,and also provides a reference for the optimization design of submarine cable structures.
基金supported by the Global Energy Interconnection Group Co.,Ltd.Science and Technology Project(Project No.101662224/Title:UHV large-capacity DC submarine cable key technology and roadmap research)the National Key R&D Program of China(2016YFB0900702)
文摘Power transmission across the sea is an important part of global energy interconnection(GEI).To support the construction of GEI and to serve the needs of future clean energy trans-sea transportation and offshore wind power development,this study a)analyzes the requirements of the GEI backbone network pertaining to direct current(DC)submarine cable technology,and b)defines the key technical and economic indices of ultrahigh-voltage direct current(UHVDC)submarine cable based on theoretical computations.The research is based on the thermoelectric coupling model and the finite element method.It is shown that the dielectric strength of the insulating materials of the±800 kV~±1100 kV/4000 MW^12000 MW UHVDC submarine cable(extrusion insulation)should be not less than 43~65 kV/mm,while the heat resistance is not less than 110°C.As the cost of submarine cable is 5~10 times higher than that of the overhead line,the project investment need to be decreased to a level within the economical carrying capacity to guarantee extensive applicability of the HVDC submarine cable technology.
基金The National Scientifi c and Technological Support Project of MST Under Grant No. 2006BAC13B02-0106the Special Research Fund for the Public Institute of China, IGP,CEA Under Grant No. DQJB06A01
文摘Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to submarine cables are summarized, which include seabed displacement induced by fault movement, submarine landslides and seabed soil liquefaction, etc. The damage is similar to damage observed to buried pipelines following land earthquakes. The Hengchun earthquake of Dec. 26, 2006 is used as a case study. The M7.2 earthquake occurred in the South China Sea at 20：26 Beijing Time, and caused 14 international submarine cables to sever and break. The results show that the proposed method predicts damage similar to that observed in the Hengchun earthquake. Based on parametric studies of the influence of the water depth and the magnitude of the submarine earthquake, countermeasures to prevent damage to submarine cables are proposed.
基金The financial supports provided by the National Natural Science Foundation of China(Grant Nos.41230636,41372265,41427801)National Basic Research Program of China(973 Project)(Grant No.2011CB710605)
文摘Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a distributed measurement system for in-situ soil moisture content （SM-DTS） is introduced.The system is based on carbon-fiber heated cable （CFHC） technology that has been developed to enhancethe measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristicvalue （Tt） can be defined from temperatureetime curves. A relationship among Tt, soil thermalimpedance coefficient and soil moisture content is then established in laboratory. The feasibility of theSM-DTS technology to provide distributed measurements of in-situ soil moisture content is verifiedthrough field tests. The research reported herein indicates that the proposed SM-DTS is capable ofmeasuring in-situ soil moisture content over long distances and large areas.
文摘海底电缆作为各类海上平台能源供给的生命线,一旦发生故障将产生巨大的经济及战略影响,准确预测海底电缆运行状态有助于提前把握其运行风险,从而实现预防性维护。在充分挖掘海底电缆运维数据中的动、静态特征的基础上,提出了一种基于注意力机制和卷积神经网络-门控循环神经网络(convolutional neural networks-gated recurrent unit, CNN-GRU)海底电缆运行状态预测方法。首先,考虑在线监测、巡检指标、静态试验三类关键影响因素,建立海底电缆运行状态评估指标体系;然后,基于改进层次分析法及多层次变权评估思想构建海底电缆运行状态评估模型;最后,建立基于注意力机制和CNN-GRU组合神经网络模型,将历史运行参数及状态量化结果作为输入特征参量,实现海底电缆运行状态的演化趋势预测。算例分析表明,所提方法可有效预测海底电缆的运行状态,平均百分数误差低至1.04%,与全连接神经网络、CNN、CNN-长短期记忆神经网络(long short term memory, LSTM)等算法相比均具备更优的预测精度。
