直流接地极及杆塔接地网附近电磁场的有限元分析

高压直流输电系统处于单极大地回线运行方式时，有很大的直流电流通过直流接地极流入大地，这将造成接地极本身及附近输电杆塔接地网的腐蚀。在理论分析接地极和杆塔接地网电磁场的基础上，应用有限元分析软件COMSOL Multiphysics，以德宝直流输电工程千阳接地极为例，建立了多层大地土壤结构下的直流接地极和杆塔接地网数值模型，添加相关边界条件，进行网格划分处理，计算分析了接地极地表电位分布规律，并对杆塔接地网附近电位及泄漏电流密度进行了研究，结果发现:接地极地表电位沿径向距离逐渐降低；杆塔接地网本体上的电位最高，接地网的射线末端泄漏电流密度最大， 射线首端的泄漏电流密度最小，接地网矩形与射线的连接处电流密度有突变。该研究对掌握直流接地极及杆塔接地网周围电场分布情况和腐蚀规律，具有重要的意义。

Finite Element Analysis of Electromagnetic Field near HVDC Grounding Electrode and Tower Grounding Grid

When the HVDC power system operates in the single pole ground return mode, there is a large amount of DC current flowing into the earth through the grounding electrode, causing corrosion of the grounding electrode and nearby transmission line grounding grid. Based on the theoretical analysis of the electromagnetic field of ground pole and tower grounding grid, this paper applies the finite element analysis software COMSOL Multiphysics to the Qianyang grounding electrode of the Deyang-Baoji DC transmission project (as an example), and establishes the numerical models of grounding electrode and tower grounding grid under a multilayer soil structure, calculating and analyzing the distribution law of the ground electrode surface potential by mesh processing and adding the related boundary conditions, and in addition, the paper studies the potential and leakage current density near the tower grounding grid. The study result shows that the grounding electrode surface potential is gradually reduced along the radial distance; the potential on the body of tower grounding grid is the highest; and the leakage current density at the end terminal of the grounding grid is the largest while the leakage current density in the head terminal of the radial is the smallest; and there is a sudden change of the current density at the junction between the grounding grid rectangle and the radial. The research in this paper is of great significance to grasp the distribution of electric field and corrosion law around grounding electrode and tower grounding grid.