高压直流输电线路下空间颗粒物荷电及运动模型研究

Large-scale construction of UHVDC transmission projects will be implemented in the northern area of China recently. The meteorology of haze and sandstrom occurs frequently in the northern area. The aerosol particles suspended in the polluted atmosphere can cause the total electric field of the UHVDC transmission line increase evidently, which has not been considered in the present UHVDC line design. One major contribution to the phenomenon is the charging and motion of the aerosol particles, therefore, it is important to investigate their physical processes and impact factors to evaluate the electric field level. Existing domestic and overseas researches about the charging and motion of aerosols are proposed mainly to the problem of electrostatic precipitation, which are inappropriate to the aerosols problem of DC transmission line due to the wide ranges of the electric field and the practical particle diameters, and to the large amount of the particles. In this project, the charging model combining field-charging and diffusion-charging mechanisms, and the dynamics model of the microscopic particle will be established to the features of the transmission lines, the macroscopic charging and dynamics models of the particles will be constructed in term of the probability of collisions between the particles and ions, and the whole mathematical model consisted of the charging and dynamics models of the particles and the total electric field model of the DC transmission line will be resolved in a preliminary way and verified by comparison with experimental results. The conclusions of the project can establish theoretical basis for the electromagnetic environment prediction of UHVDC transmission line in the northern area of China, and provide technology support to the balance between environmental protection and resource saving.

我国北方地区即将大规模建设特高压直流输电工程，北方地区雾霾、沙尘天气频发，空气污染情况下的空间颗粒物将造成直流线路的地面合成电场显著增大，现有高压直流线路设计尚未考虑此因素影响。空间颗粒物的荷电与运动是导致地面合成电场增大的重要原因，需要对其物理过程和影响因素开展深入研究。国内外已有的颗粒物荷电与运动研究主要针对静电除尘问题，而直流线路具有合成电场变化范围大和附近空间颗粒物粒径跨度大、总量大等特点，现有结果无法满足分析需求。本项目拟开展适用于直流线路合成电场范围的大粒径跨度微观颗粒物电场-扩散联合荷电模型和运动模型、综合颗粒物与离子碰撞概率的颗粒物宏观荷电模型和运动模型等研究，构建直流线路与空间颗粒物的荷电-运动-合成电场综合数学模型，初步探索求解方法，并与实验结果对比验证。本项目的研究结果可为北方地区特高压直流线路的电磁环境预测奠定理论基础，为特高压工程环境保护和资源节约的统一提供支撑。

我国北方地区已开始大规模建设特高压直流输电工程，北方地区雾霾、沙尘天气频发，空气污染情况下的空间颗粒物将造成直流线路的地面合成电场显著增大，现有高压直流线路设计尚未考虑此因素影响。空间颗粒物的荷电与运动是导致地面合成电场增大的重要原因，需要对其物理过程和影响因素开展深入研究。而直流线路具有合成电场变化范围大和附近空间颗粒物粒径跨度大、总量大等特点，现有结果无法满足分析需求。本项目提出了一种同时考虑颗粒物电导率和介电常数的悬浮颗粒物电场荷电模型，获得了颗粒物和媒质的电导率和介电常数影响颗粒物荷电过程的规律，与实验结果进行了对比验证；基于提出的电场荷电模型，提出了电场-扩散荷电量组合模型，在大跨度电场强度和颗粒物粒径参数范围内与实验结果进行了对比验证；分析了不同电场范围内不同粒径颗粒物的受力情况，提出了颗粒物的宏观运动模型；建立了计及不同成分和粒径悬浮颗粒物影响的高压直流输电线路合成电场理论模型并提出了相应的计算方法，将计算结果与北京特高压直流试验线路在空气污染条件下的地面合成电场试验结果进行对比，验证了模型和计算方法的有效性。本项目建立的理论模型和计算方法可在线路设计阶段计算线路在不同地区、各种污染条件下满足地面合成电场要求的导线最小对地高度和走廊宽度，提出有效的电磁环境控制措施。研究结果可为北方地区特高压直流线路的电磁环境预测奠定理论基础，为特高压工程环境保护和资源节约的统一提供支撑。