基于有限元迭代法的高压直流输电线路离子流场仿真计算

直流导线电晕放电产生的离子流场是限制直流输电发展的主要因素之一。为分析离子流对原有电场分布畸变影响,通过COMSOL和MATLAB联合仿真实现了有限元迭代法,基于该方法对高压直流导线附近离子流场进行了研究。仿真模型采用网格加密以及强耦合的方法提高了计算的收敛性,采用与放电特性相关的方程作为电荷边界条件,以提高仿真计算的准确性;比较两类起晕场强计算公式的准确性,选择较为准确的计算公式作为迭代标准;将同轴圆柱模型的解析解与仿真的数值解进行比较,验证有限元迭代法计算高压直流离子流场的准确性;最后分析单极+800 kV直流输电线路周围的离子流场。结果表明,离子流使得地面附近的电场强度增大了30%,可见离子流对导线周围电磁环境有重大影响,在直流输电线设计时应该考虑这一因素。

Simulation of Ion Flow Field around HVDC Transmission Line based on Finite Element Iteration Method

Abstract] The ion flow field generated by the corona discharge of direct current wire is one of the main factors limiting the development of direct current transmission. In this paper, the finite element iterative method is realized by the joint simulation of COMSOL and MATLAB in order to analyze the influence of ion current on the distortion of original electric field distribution. Based on this method, the ion flow field near the high-voltage direct current wire is analyzed. Mesh refinement and strong coupling methods are used in the model to improve the convergence of simulation calculations. Equations related to discharge characteristics are used as charge boundary conditions to enhance the accuracy of simulation calculations. Comparing the accuracy of two formulas for calculating the electric field intensity of corona onset, the more accurate formula is selected as the iteration criteria. Then the analytical solution of the coaxial cylindrical model is compared with the numerical solution to verify the accuracy of the finite element iteration method in calculating the high voltage direct current ion flow field. Finally, the ion flow field around the unipolar +800kV direct current wire is analyzed. The results show that the electric field near the ground is increased by 30% due to the ion current, hence the ion current has a significant impact on the elec-tromagnetic environment around the wire, which should be considered in the design of Direct Current transmission line. Key words] corona discharge ion flow finite element iterative method peek formula semi empirical formula