磁性粒子调控半导电层内部电荷迁移路径及界面电荷注入机制研究

绝缘层中空间电荷积聚是制约高压直流电缆发展的关键问题之一。内半导电屏蔽层在电缆结构中起到均匀电场的作用，同时也是电荷由金属向绝缘层注入的必经路径，影响绝缘层电荷积聚。本项目提出通过磁性粒子改性半导电层，利用电场力和洛伦兹力的协同作用调控半导电层内部电荷迁移路径，减少半导电层-绝缘层界面电荷注入的研究思路。通过改变半导电层中SrFe12O19粒径、含量和磁化方向，控制半导电层磁场大小和方向；通过测量半导电层影响下绝缘层空间电荷、电导电流场强关系和去极化电流，获得磁性粒子参数对绝缘层电荷积聚的影响规律。考虑电-热-磁的共同影响，建立半导电层内部电荷迁移及界面电荷注入模型，研究半导电层内部电荷随时间的运动轨迹及界面电荷注入行为，优化调控方案；阐明通过磁性粒子改性半导电层减少绝缘层电荷积聚的物理机制。该工作可为直流电缆绝缘层空间电荷抑制提供新方法，对半导电料开发和电缆绝缘水平整体提升具有重要意义。

Space charge accumulation in the insulation layer is one of the key problems restricting the development of HVDC cable. The inner semi-conductive shielding layer plays the role of the uniform electric field in the cable structure, and it is also the necessary path for charge injection from the metal to the insulation layer, which affects the charge accumulation in the insulation layer. In the project, a research idea of modifying the semi-conductive layer by the magnetic particles was proposed, which using the synergistic effect of electric field force and Lorentz force to control the internal charge migration path within the semi-conductive layer to reduce the charge injection at the interface between the semi-conductive layer and the insulation layer. The magnitude and direction of the magnetic field in the semi-conductive layer were controlled by changing the particle size, content, and magnetization direction of SrFe12O19 in the semi-conductive layer. The influence of magnetic particle parameters on the charge accumulation of the insulation layer was obtained by measuring space charge, the conductive current, and depolarization current under the action of the semi-conductive layer. Further, charge transfer in the semi-conductive layer and the interface charge injection model was established considering the influence of the electric field, magnetic field, and temperature field. The movement trajectory of charge with time in the semi-conductive layer and the interface charge injection behavior were studied to optimize the material modification scheme. The physical mechanism of reducing the charge accumulation in the insulation layer by modifying the semi-conductive layer with magnetic particles was revealed. This work can provide a new method for the space charge suppression of HVDC cable, and is of great significance for the development of semi-conductive materials and the improvement of cable insulation levels.