The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines' electromagnetic environment.Based on...The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines' electromagnetic environment.Based on analyzing the existing TEF sensors and the measurement principle of ion-current density,the influence from ions on TEF measurements is quantitively studied.The results show that the ions generated by the corona from a HVDC transmission line in operation cause errors in the measurement of TEF.This error is determined through analyzing the component of total measuring current on the filed mill's sensing electrode: if no appropriate approach taken,the maximum measurement error reaches up to 4.3%.Furthermore,a method that can eliminate such error,and hence improve the accuracy of TEF sensors is designed.展开更多
An upwind finite element(FE)based algorithm to calculate the ion flow field in the vicinity of multi-circuit DC transmission lines is described.The initial value estimation and boundary condition are optimized,so deta...An upwind finite element(FE)based algorithm to calculate the ion flow field in the vicinity of multi-circuit DC transmission lines is described.The initial value estimation and boundary condition are optimized,so details of the transmission lines such as bundle conductors and ground wires can be taken into account in the simulation model.Comparison between measured and computed ground level total electrical field and ion current density shows satisfactory agreement.The ion flow field of a ±500 kV HVDC project with bipolar lines on the same tower is simulated.The total electrical field and ion current density on ground level are compared among different line arrangements.展开更多
A 3-dimensional resistive MHD simulation was carried out to study the effect of the upward ions on the field-aligned currents (FACs) in the near-earth magnetotail. The simulation results show that the up-flow ions ori...A 3-dimensional resistive MHD simulation was carried out to study the effect of the upward ions on the field-aligned currents (FACs) in the near-earth magnetotail. The simulation results show that the up-flow ions originating from the nightside auroral oval would drift into the center plasma sheet along the magnetic field lines in the plasma sheet boundary, and have an important effect on the field-aligned currents. The main conclusions include that: 1) the upward-ions mainly affect the field- aligned currents in the near-earth magnetotail (inside 15 Re); 2) the generated FACs in the near-earth region have two types, i.e., Region 1 FAC in the high-latitude and Region 2 FAC in the low-latitude; 3) FACs increase with the enhancement of the upward ion flux; 4) with the same flux of the upward ions, FACs enhance with the increase of the velocity of the up-flow ions; 5) the intensification of FACs is also closely related with the latitude of the upward ions, and the ions from the closed field line region generate larger FACs; 6) the generation of FACs is closely related with By created by the upward ions.展开更多
特高压直流(UHVDC)输电线路地面离子流场的大小是检验电磁环境是否超标的重要判据,对不同风速条件下的地面离子流场的分布进行了计算研究。针对离子流场的计算,提出一种改进迭代上流有限元方法,建立了考虑风速影响的离子流场模型。研究...特高压直流(UHVDC)输电线路地面离子流场的大小是检验电磁环境是否超标的重要判据,对不同风速条件下的地面离子流场的分布进行了计算研究。针对离子流场的计算,提出一种改进迭代上流有限元方法,建立了考虑风速影响的离子流场模型。研究了不同风速对±800 k V输电线路离子流场分布规律的影响。研究表明,地面最大合成场强和离子流密度随风速的增大而增加明显,且风速会使其发生一定偏移。考虑风速为8 m/s时,地面最大合成场强比无风增加了12.64 k V/m,且地面最大离子流密度是无风时的2.65倍。水平风速越大地面合成场强和离子流密度的分布曲线和峰值往背风向偏移越严重,空间其他较远处的合成场强和电荷密度变化不大,且空间合成场强与电荷密度的最大值主要分布于导线周围空间。展开更多
基金Project supported by National Natural Science Foundation of China （61273165 51207005）.
文摘The total electric field(TEF) at ground level induced by high-voltage direct current(HVDC) overhead transmission lines is one of the important indexes for evaluating the lines' electromagnetic environment.Based on analyzing the existing TEF sensors and the measurement principle of ion-current density,the influence from ions on TEF measurements is quantitively studied.The results show that the ions generated by the corona from a HVDC transmission line in operation cause errors in the measurement of TEF.This error is determined through analyzing the component of total measuring current on the filed mill's sensing electrode: if no appropriate approach taken,the maximum measurement error reaches up to 4.3%.Furthermore,a method that can eliminate such error,and hence improve the accuracy of TEF sensors is designed.
基金Project Supported by China11th Five-year National Key Technologies R&D Program(2006BAA02A20)
文摘An upwind finite element(FE)based algorithm to calculate the ion flow field in the vicinity of multi-circuit DC transmission lines is described.The initial value estimation and boundary condition are optimized,so details of the transmission lines such as bundle conductors and ground wires can be taken into account in the simulation model.Comparison between measured and computed ground level total electrical field and ion current density shows satisfactory agreement.The ion flow field of a ±500 kV HVDC project with bipolar lines on the same tower is simulated.The total electrical field and ion current density on ground level are compared among different line arrangements.
基金Supported by the National Natural Science Foundation of China (Grant Nos. CNSF-40474058 and CNSF-40536030)
文摘A 3-dimensional resistive MHD simulation was carried out to study the effect of the upward ions on the field-aligned currents (FACs) in the near-earth magnetotail. The simulation results show that the up-flow ions originating from the nightside auroral oval would drift into the center plasma sheet along the magnetic field lines in the plasma sheet boundary, and have an important effect on the field-aligned currents. The main conclusions include that: 1) the upward-ions mainly affect the field- aligned currents in the near-earth magnetotail (inside 15 Re); 2) the generated FACs in the near-earth region have two types, i.e., Region 1 FAC in the high-latitude and Region 2 FAC in the low-latitude; 3) FACs increase with the enhancement of the upward ion flux; 4) with the same flux of the upward ions, FACs enhance with the increase of the velocity of the up-flow ions; 5) the intensification of FACs is also closely related with the latitude of the upward ions, and the ions from the closed field line region generate larger FACs; 6) the generation of FACs is closely related with By created by the upward ions.
文摘特高压直流(UHVDC)输电线路地面离子流场的大小是检验电磁环境是否超标的重要判据,对不同风速条件下的地面离子流场的分布进行了计算研究。针对离子流场的计算,提出一种改进迭代上流有限元方法,建立了考虑风速影响的离子流场模型。研究了不同风速对±800 k V输电线路离子流场分布规律的影响。研究表明,地面最大合成场强和离子流密度随风速的增大而增加明显,且风速会使其发生一定偏移。考虑风速为8 m/s时,地面最大合成场强比无风增加了12.64 k V/m,且地面最大离子流密度是无风时的2.65倍。水平风速越大地面合成场强和离子流密度的分布曲线和峰值往背风向偏移越严重,空间其他较远处的合成场强和电荷密度变化不大,且空间合成场强与电荷密度的最大值主要分布于导线周围空间。
