大地电导率横向变化对地磁暴感应电场H极化及地磁感应电流的影响

摘要

磁暴感应地电场在输电网、铁路、管线中产生地磁感应电流（GIC），对设备的正常运行产生不利影响。大地电导率的横向差异使磁暴感应地电场在海岸等复杂地质结构地区发生畸变，而“海岸效应”就是H极化情况下的一种典型畸变现象。本文考虑大地电导率的横向变化建立了分块模型，应用有限元法计算了H极化情况下磁暴感应地电流场的分布，定量分析电导率变化系数与地电场畸变现象之间的关系，揭示大地电导率横向差异对地电场分布的影响规律；假设变电站位于分界面附近，讨论电导率变化系数、变电站与分界面距离等因素对线路GIC的影响，为电网GIC的准确计算提供理论基础。%During magnetic storms, the induced geoelectric fields drive geomagnetically induced currents (GIC) in power transmission networks, railway systems and pipelines, resulting in negative effects on those systems. In the region with complex geological structure, such as coast area, the lateral change of earth conductivity will cause distortion in the distribution of induced geoelectric field. The coast effect is a typical distortion of geoelectric field in the “H polarization” case and it has obvious impacts on GIC. This paper simulated the influence of the “H polarization” on the earth electric field due to magnetic storm. After establishing the earth model with lateral conductivity change, this paper used the finite element method to solve the boundary problem of the induced telluric current field. Thus, the relationship between conductivity lateral change and electric field distortion was discussed based on the numerical results. Additionally, this paper also discussed the variation of GIC in the power grid due to the lateral conductivity change and the distance between substation and the conductivity interface. The method and the results lay a theoretical foundation for the accurate calculation of GIC in the power grid.